energy and earth science vol. 4, no. 1, 2021 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 14 original paper doppler and an end of expansion paul schroeder 1 1 8244 anna ave., wind lake, wisconsin 53185, usa received: february 3, 2021 accepted: february 22, 2020 online published: march 9, 2021 doi:10.22158/ees.v4n1p14 url: http://dx.doi.org/10.22158/ees.v4n1p14 abstract the concept today is that our universe is in a state of expansion as everything is moving away from us, and away from everywhere. this idea is specifically a conclusion to the finding of the frequency of the waves of light from the source being distorted, theoretically by the motion of the source relative to the observer. the frequency variation is called doppler which was originally assigned to distorted sound from arriving trains. this is an analysis of doppler theory that revels that a redshift of star light beams occur when the stars are “revolving” relative to an observer (such as us on earth). everything in space does revolve around an observer. think about this! keywords expansion, light wave frequency, doppler, revolution, rotation, wikipedia, external gravity 1. introduction astrophysics theory leading to expansion and the big bang is built around the original doppler explaining that motion away causes frequency shifts. the theory is an extension of the doppler theory developed in 1832 and 1851 from considering sound frequency changes as a train approaches an observer. light might also produce a doppler shift of light frequency as the source approaches an observer causing a redshift. when red shifting of light in galaxies was initially observed by edwin hubble in the 1920‟s, hubble and associated ultimately proposed the redshift source was caused by motion apart/away. there is logic to that so such a model was adopted. later on the motion away was noticed to be greater as the star/galaxy was further away. that implies the idea of the motion increasing with distance. thus the expansion idea came to be and was sold to the physics world. over time that led to unnatural ideas including the big bang. we can understand that initial thoughts about redshift implying motion away, logically. motion away would stretch the wave within the beam as seen by the observer. it is now many years later that the additional doppler concept found that revolution of sources would also redshift the light to a central www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 15 published by scholink inc. observer. seeking logic, the redshift from revolving sources causing redshift is the more sensible idea. if you have now “thought about that” and contemplated this, logic says light will redshift when the source moves away, but light will also redshift, when the source revolves relative to us. thus a retaining of distance will also redshift star lights. understanding such things improves if you have a full model of the universe from a totally different perspective. there are a number of physics concepts which have questionable grounds which are more easily seen such as my “universe is otherwise—external gravitation” model of the universe. 2. wikipedia wikipedia is an original and the ultimate “on line encyclopedia” of physics and other sciences. in the wikipedia i found that doppler redshift, originally known to be caused by motion toward or away, is also caused by revolving sources. the wiki analysis is clear enough that one would expect it would have alerted physics to the alternate redshift causes and led to debating the validity of the idea of expansion. expansion and the conclusions that have resulted from it are one half of the standard model that leads all of physics. this is the big bang portion. the other half is the universe is-that all actions occur based on probability. the two pieces have been included together as they differ from each in understanding gravity. the proper view should be on that of the destination/detector as that is where the frequency is of concern, i.e., where we see it. the solution for ending expansion lies with doppler‟s logical option. this comes from wikipedia. see under doppler of light-relativistic doppler effect-wikipedia. i have copied here the three situations that lead to red shift. beginning here, what i write will be in purple to segregate my ideas and comments from the specific wiki writing. the rest in black is directly from wikipedia. 2.1 moving away gives redshift relativistic doppler shift for the longitudinal case, with source and receiver moving directly towards or away from each other, is often derived as if it were the classical phenomenon, but modified by the addition of a time dilation term 2.2 transverse, but not directly away redshift receiver sees the source as being at its closest point https://en.wikipedia.org/wiki/time_dilation www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 16 published by scholink inc. figure 1. transverse doppler shift for the scenario where the receiver sees the source as being at its closest point this scenario is equivalent to the receiver looking at a direct right angle to the path of the source. the analysis of this scenario is best conducted from the frame of the receiver. figure 3 shows the receiver being illuminated by light from when the source was closest to the receiver, even though the source has moved on. because the source‟s clock is time dilated as measured in the frame of the receiver, and because there is no longitudinal component of its motion, the light from the source, emitted from this closest point, is redshifted with frequency in the literature, most reports of transverse doppler shift analyze the effect in terms of the receiver pointed at direct right angles to the path of the source, thus seeing the source as being at its closest point and observing a redshift. 2.3 circular picture a is not relevant, b is the key. note the red dots one object in circular motion around the other figure 2. transverse doppler effect for two scenarios: (a) receiver moving in a circle around the source; (b) source moving in a circle around the receiver figure 5 illustrates two variants of this scenario. both variants can be analyzed using simple time dilation arguments. figure 5a is essentially equivalent to the scenario described in figure 2b, and the receiver observes light from the source as being blue shifted by a factor of. figure b here is the one that matters as it is what we see. figure 5b is essentially equivalent to the scenario described in figure 3, and the light is redshifted. https://en.wikipedia.org/wiki/file:transverse_doppler_effect_scenarios_4.svg https://en.wikipedia.org/wiki/file:transverse_doppler_effect_scenarios_5.svg www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 17 published by scholink inc. 3. important analysis astronomers know of three sources of redshift/blueshift: doppler shifts; gravitational redshifts (due to light exiting a gravitational field); and cosmological expansion (where space itself stretches). this article concerns itself only with doppler shifts. note that the third source by wiki here is “cosmological expansion” which is the fantasy with no conformation beyond the early doppler. once the transfer in figure 5 b is understood, the redshift is much more likely to come from the rotation of the sky relative to us as observers. the picture in figure 3 is also redshift that does not signal motion away. the idea of motion away becomes “circular” reasoning and may have never existed. the second source by wiki, listed here, is the always ignored gravitational redshift. this cause agrees with the basis of my gravity theory as it overrides the idea of a constant speed c. the exit from a gravitational field results in a slowing of the speed of the light beam and thus thus red shift occurs. the first source here by wiki is doppler shifts. as shown doppler gives various impressions of the motion of the source that must be resolved. a doppler redshift can arrive from various relative motions of stars. so we can choose to accept that „the sky of all-stars‟ is in circular motion around earth. (or any other central body one chooses). that circular motion adds some redshift to the light sent by all stars. everything in space revolves around us over time and we see, detect, and measure that flow. but any motion away in galaxies is not visible to us. the whole concept of expansion is a figment of guessing that redshift proves motion away. it doesn‟t! you may ask why revolving stars cause a redshift when we receive their light. the passage of light is never a straight line, neither for the source nor for the observer. light emitted by a central body, the sun for earth or the earth for the moon must curve to arrive. fortunately there is the rotation of the center body which helps cause the curve or bend. at the same time its rotation curves gravity beams that push the orbital body in its orbit path. 4. gravity i mentioned that the big bang and probability share the standard model because of conflicting views of gravity. my “universe is otherwise” model is all about gravity and it is the best explanation of gravity. first of all gravity must exist since it causes motions. to do so it must push! a pull or attraction by itself moves nothing and isn‟t logical. then the push must be everywhere, so it is component of the universe and space. notice that we are trying to define gravity. space can‟t be empty as argued between newton and einstein models. thus space is full of em radiation so radiation is related to gravity. the em radiation does move as we know, and being something, it can push. physics has created problems by limiting pressure to moving matter. separating radiation from matter has removed it from calculations of pressure. they identify radiation as non-particle. removing the separation is a simple answer to the dual wave or matter conflict. reality is that anything that moves can cause pressure. https://en.wikipedia.org/wiki/redshift https://en.wikipedia.org/wiki/blueshift https://en.wikipedia.org/wiki/gravitational_redshift https://en.wikipedia.org/wiki/cosmological_expansion www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 18 published by scholink inc. em radiation and gravity are the components of space. they are “one” with multiple attributes. the flow of gravity is everywhere and essentially similar throughout. from newton‟s time gravity has been assumed to be caused by matter. local gravity is focused at the center of earth. to correct that, consider the less specific statement that the push of gravity is “affected by” matter. that requires defining some more activity. since gravity and em radiation flow throughout the universe, therefore they can penetrate and flow through matter. the time of the flow of gravity flow thru matter causes a reduction of the push pressure as well as a modification of the em radiation in some form. the lesser push of exiting gravity beams interacts with unaffected downward flowing gravity beams and the net is the apparent attraction force. there are many different perspectives connected with this “pushing” gravity model identified throughout “the universe is otherwise”. one i will touch on here is the major issue of the infinite nature of the universe. finity vs infinity are perhaps the principal forms of the universe that have been argued over the centuries. my otherwise model requires an infinite universe. radiation flows from everywhere and may carry light from stars. refer to the wiki statement above about redshift, gravitational redshifts (due to light exiting a gravitational field). so the stars net gravity affect upon its own light occurs, red shifting the beam, and continues as beams travel. the more distant, the more red shifting that occurs. at some very far distant from the star, its beam will have experienced redshift beyond red and into the microwave region. thus we detect a microwave background approximately equal from all directions. the universe provides balance of light as the redshift that occurs over long distance travel is offset as beams of all frequency are upshifted to light as beams penetrate bodies. the big bang finite universe is supported by the church as it provides a beginning as the bible promotes. any loss of the beginning is not acceptable. but really, the infinite universe allows an infinite god and the gravity of space serves as the holy ghost. we then jointly serve as the son. these analogies are lost in the finite universe. 5. conclusion for considering the doppler applied to redshift, the bottom line is that the curve of the beam path from a star to us stretches the wave length and thus reduces the frequency of a star‟s light just as motion away by the star reduces the frequency of its light. . this alternate doppler effect is quite logical within the nature of gravity. gravity is space throughout and makes up the nature of all space. attraction is simply a push upon arrival by a flowing pressure. that pressure is the flow of all forms of em radiation. that em radiation which serves as gravity for the transfer of a light beam jointly transfers the light beam. any rotational motion of any star means you can‟t draw a straight line to earth for the beam. a beam starts toward earth and arrives after the star has moved some lateral distance relative to earth. essentially the beam must offset that lateral distance as well as any direct line toward earth. thus a longer path is https://en.wikipedia.org/wiki/gravitational_redshift www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 19 published by scholink inc. assumed. it turns out that the rotation of the star itself can contribute to causing the long path. if you have accepted the perspectives given here perhaps you can help mankind reach that acceptance. references greg, v. (2011). a matter of definition. proceedings of the space, propulsion & energy sciences international forum. in the meaning of maxwell’s equations (unpublished). isaac, n. (2003). the world of mathematics, 1, 261. leonardo, m. (n.d.). “1905 and all that”, on internet quoted in eric weissteins world of physics under michelson morley experiment-ether. paul, s. (2006). the universe is otherwise (booksurge/createa-space, 2006). paul, s. (2008). “motions, rotations and revolutions” (the universe is otherwise: part 3). retrieved from http://www.worldsci.org/ php/index.php?tab0=abstracts&tab1=display&id=3229&tab=2 paul, s. (2008). “paeps: external gravity particles” (the universe is otherwise: part 1). retrieved from http://www.worldsci.org/php/index. php?tab0=abstracts&tab1=display&id=3224&tab=2 paul, s. (2008). “the spectrum of existence” (the universe is otherwise: part 2). retrieved from http://www.worldsci.org/php/index.php ?tab0=abstracts&tab1=display&id=4152&tab=2 paul, s. (2010). gravity from the ground up. proceedings of the npa, 7, 498-503. paul, s. (2011). get “real” about gravity. proceedings of the npa, 8, 521-529. paul, s. (2011). ignoring newton‟s hints brought scientific chaos. proceedings of the npa, 8, 521-529. paul, s. (2012). creating matter from em radiation. proceedings of the npa, 9, 510-513. paul, s. (2012). gravity and revolution rates within galaxies. proceedings of the npa, 9. paul, s. (2013). creating matter from em radiation. proceedings of the npa, 10. paul, s. (2013). mass rotation controls orbiting. proceedings of the npa, 10. paul, s. (2016). external gravity theory and gravity “bumps” during eclipses. paul‟s cabinet. https://doi.org/10.4172/2090-0902.1000228 paul, s. (2018). “infinity and pushing gravity lead to revelations” (the universe is otherwise part 2c). proceedings of the cnps (2016), global journal. paul, s. (2018). “infinity and reality” (the universe is otherwise part 2a). proceedings of the cnps (2016), global journal. paul, s. (2018). “structure and gravity” (the universe is otherwise part 2b). proceedings of the cnps (2016), global journal. paul, s. (2018). infinite and reality—the universe is otherwise-part 2a. the global journal of space science. paul, s. (2018). infinity and pushing gravity lead to revelations—the universe is otherwise-part 2c. the global journal of space science. paul, s. (2018). structure and gravity—the universe is otherwise-part 2b. the global journal of space science. https://doi.org/10.4172/2090-0902.1000228 www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 20 published by scholink inc. paul, s. (2019). the physical nature of the electron. paul‟s cabinet. paul, s., arthur, r., & robert, d. h. (2016). gravity is a pushing force. proceedings cnps. yang, x. s., & wang, q. s. (2002). gravity anomaly during the mohe total solar eclipse. astrophysics and space science, 282, 245-253. https://doi.org/10.1023/a:1021119023985 https://doi.org/10.1023/a:1021119023985 energy and earth science vol. 2, no. 2, 2019 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 45 study on effect of superplasticizer on ggbs blended geopolymer concrete vahini m.1*, k. manjunatha2, venkatesh3 & basappa meti1**, 1 department of civil engineering, government engineering college, haveri, india 2 vtu regional office, mysore, india 3 government engineering college, kushalnagara, india * vahini m., e-mail: vahini_cta@yahoo.com; ** basappa meti, e-mail: bsmeti@gmail.com received: june 21, 2019 accepted: july 9, 2019 online published: september 3, 2019 doi:10.22158/ees.v2n2p45 url: http://dx.doi.org/10.22158/ees.v2n2p45 abstract geopolymer concrete is an alternate to conventional concrete with reduced carbon emission, embodied energy and global warming potential and transforming waste product into an useful material. geopolymer concrete is produced by mixing highly alkaline activator solution with alumino silicate source materials. geopolymer concrete is highly viscous or sticky in nature, to overcome this drawback, an attempt has been made to study the effect of naphthalene based superplasticizer on geopolymer concrete blended with ggbs. fly ash was replaced by ggbs at 20% increment levels, keeping a constant superplasticizer dosage at 3% by weight of binding material. workability and strength characteristics were compared with those of geopolymer concrete blended with ggbs without superplasticizer. up to certain replacement level of fly ash with ggbs, results in decrease of strength parameters with increase in workability, further replacement results in increase of strength with reduced workability with the addition of superplasticizer. keywords ground granulated blast furnace slag(ggbs), fly ash, superplasticizer, blended geopolymer concrete 1. introduction 1.1 general concrete is the widely used material in the world after water. ordinary portland cement has been used traditionally as a binding material for preparation of concrete. the world-wide consumption of concrete is believed to rise exponentially for the infrastructural development taking place in china and india. one tone of carbon dioxide is estimated to be released to the atmosphere when one ton of ordinary portland cement is manufactured; also the emission by cement manufacturing process contributes 7% www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 46 published by scholink inc. to the global carbon dioxide emission. it is important to find an alternate binder which has less carbon footprint than cement. geopolymer concrete is one such alternate binding material, wherein the cement is totally replaced by industrial byproducts such as fly ash, ggbs etc., with rich content of aluminium and silicon. davidovits (1988; 1994) proposed that an alkaline liquid could be used to react with the silicon (si) and aluminum (al) in a source material of geological origin or in by product materials such as fly ash and ggbs to produce binders. because the chemical reaction that takes place in this case is a polymerization process, he coined the term geopolymer to represent these binders. the final properties of geopolymer concrete is influenced by large number of factors like type of curing, water content, alkali concentration, solids content, silicate and aluminates ratio, ph and others. geopolymer concrete is highly viscous or sticky in nature, which reduces the workability. to increase the workability, extra water or superplasticizer will be added. therefore, the present work aims to study the effect of adding superplasticizer on workability and strength characteristics of ggbs blended geopolymer concrete. 1.2 constituents of geopolymer concrete geopolymer concrete can be manufactured by using the low-calcium fly ash obtained from coal-burning power stations. most of the fly ash available globally is low-calcium fly ash formed as a by-product of burning anthracite or bituminous coal. although coal burning power plants are considered to be environmentally unfriendly, the extent of power generated by these plants is increasing due to the huge reserves of good quality coal available worldwide and the low cost of power produced from these sources. the energy returned-to-energy invested ratio of coal burning power plants is high, and second only to the hydro-power generation plants. (lloyd, 2009) the main constituents of the geopolymer concrete are source materials and alkaline liquids. the source materials should be rich in silicon (si) and aluminum (al), these could be natural materials such as kaolin, clays etc. alternatively, by-product materials such as fly ash, silica fume, slag, rice husk ash, red mud etc. could be used as source materials. the choice of the source materials for making geopolymers depends on factors such as availability, cost, type of application, specific demand of the end users. the alkaline liquids are from soluble alkali metals that are usually sodium or potassium based. 2. literature review nuruddin et al. (2011) have studied the effect of superplasticizer (sp) dosage and molarity of naoh solution on workability and compressive strength of self-compacting geopolymer concrete. the workability properties such as filling ability, passing ability and resistance to segregation were assessed using slump flow, t-50, v-funnel, l-box and j-ring test methods. it was found that the essential workability requirements for self compactability were satisfied. results show that low superplasticizer content 3, 4 and 5% had poor filling and passing ability and the workability results were not satisfied the limits of self compacting concrete. as the concentration of naoh solution increased from 8m to 12m, the compressive strength of geopolymer concrete has increased. they have concluded that 6% of www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 47 published by scholink inc. sp dosage and 12m of naoh concentration as the optimum values. laskar and bhattacharjee (2012) have made an attempt to study variation of workability of fly ash based geopolymer concrete with the variation of lignin based plasticizer and polycarboxylic ether based superplasticizer. it has been observed that there exists a critical value of molar strength of sodium hydroxide beyond which superplasticizer and plasticizer have adverse effect on workability of fly ash based geopolymer concrete. below the critical molar strength of sodium hydroxide, there is an increase in slump. plasticizer and superplasticizer dosage improves workability of fly ash based geopolymer concrete for molar strength of naoh solution less than 4m. lignin based superplasticizer has been found to be more effective than pc based superplasticizer. nematollahi and sanjayan (2014) have presented a review on efficacy of available superplasticizers on geopolymers. the effect of sps on workability, strength and rheological parameters (yield stress and plastic viscosity) of slag and fly ash based geopolymer paste, mortar and concrete was comprehensively reviewed in this study. in summary, research results reported in the literature ascertain that sps do not work the same on geopolymer systems than in opc systems. the effect of sps on slag and fly ash based geopolymers directly depends on the type of binder and activators in addition to the type and dosage of the sps as well as the ph of the alkaline solution. in general, the pc based sps (latest generation) are the most effective type in the case of fly ash based geopolymer activated by naoh +na2sio3 activators. whereas, in the case of slag based geopolymers activated by naoh solution, n based sps (second generation) are the most efficient type. moreover, in most cases using sps might decrease the strength of the slag and fly ash based geopolymers with reference to the original geopolymers without using sp. nematollahi and sanjayan (2014) have evaluated the effect of different commercial superplasticizers (sps) such as naphthalene, melamine and modified polycarboxylate based on the workability and strength of a class f fly ash geopolymer paste activated by two different activator combinations i.e., 8m sodium hydroxide solution and a multi-compound activator composed of 8m naoh solution (28.6%) + na2sio3 (71.4%) with a sio2/na2o ratio of 2.0. these sps at a dosage of 1% by mass of fly ash were added to the fresh paste and flowability of the activated fly ash paste measured via mini slump test and compared with that of paste without using any sp. the experimental results indicated that the effect of different sps on the workability and strength of fly ash based geopolymer directly depends on the type of activator and the sp. in the case of using 8m naoh solution as the activator, naphthalene based sp was an effective type; whereas modified polycarboxylate based sp was the most efficient type when the multi-compound activator was used. xie and kayali (2015) have investigated the use of superplasticizers with enhanced dispersion capability for different geopolymer pastes. two types of polycarboxylate based and one type of naphthalene based superplasticizer were investigated. results showed that all the applied superplasticizers were considerably less effective with geopolymers, a higher than usual dosage of superplasticizer was needed for noticeable workability enhancements. naphthalene based www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 48 published by scholink inc. superplasticizers caused higher instantaneous slump and larger spread than polycarboxylate based type. 3. materials and methodology 3.1 materials the alumino silicate material used in this study is a combination of fly ash and ground granulated blast furnace slag (ggbs). fly ash is procured from bellary thermal power plant, kudithini. ggbs is obtained from jsw, bellary. sodium silicate and sodium hydroxide are procured from shree chem, bangalore and locally available coarse and fine aggregates are used. table 1 shows the physical properties of materials used. sodium hydroxide used is in flakes form with 97% purity, concentration of sodium silicate solution is 47.50% with na2o 14.7% and sio2 32.8%. conplast sp 430 is used as naphthalene based superplasticizer. table 1. physical properties of materials used material fly ash ggbs fine aggregate coarse aggregate specific gravity 2.20 2.79 2.42 2.5 3.2 mix proportions as there are no codal provisions for the mix design of geopolymer concrete, the geopolymer concrete mix was prepared as per the procedure given by patankar et al. the alkaline liquid to fly ash ratio is kept as 0.35. the ratio of sodium hydroxide to sodium silicate is taken as 1.00 concentration of sodium hydroxide solution is maintained as 13m. mix design is carried out for m30 grade of geopolymer concrete. quantity of materials required is shown in table 2. table 2. quantity of ingredients of m30 geopolymer concrete ingredient of geopolymer concrete fly ash naoh na2sio3 sand coarse aggregate total water content extra water quantity ( kg/m3) 405 70.875 70.875 686.81 1261.56 110 31.48 3.3 casting and curing fine aggregate, coarse aggregate, fly ash are mixed in dry condition for 3-4 minutes and then the alkaline solution, which is a combination of sodium hydroxide solution and sodium silicate solution with superplasticizer dosage of 3% by weight of binding material is added to the dry mix. figure 1 shows the casting of specimens. specimens are demoulded after 24 hrs of casting and kept in ambient condition for curing as shown in figure 2. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 49 published by scholink inc. figure 1. casting of specimens figure 2. specimens at ambient curing 4. results and discussions the specimens are designated as fa100 for 100% fly ash and fgn for fly ash and ggbs blends at n% of fly ash. fly ash is replaced at an increment of 20% by weight with ggbs. workability and strength characteristics are studied for ggbs blended geopolymer concrete with and without sp. figure 3. slump for ggbs blended geopolymer concrete with and without superplasticizer workability in terms of slump is shown in figure 3. it is observed that the slump for geopolymer concrete with superplasticizer is more when compared with geopolymer concrete without superplasticizer, for all replacements of fly ash with ggbs. slump for geopolymer concrete without superplasticizer, reduces with increase in ggbs level but for geopolymer concrete with superplasticizer, slump increases up to 40% replacement of fly ash with ggbs and then it decreases which may be due to the presence of calcium in ggbs. strength properties such as compressive strength, split tensile strength and flexural strength are conducted for ggbs blended geopolymer concrete with and without superplasticizer and the results are shown in table 3. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 50 published by scholink inc. table 3. strength properties of geopolymer concrete blended with ggbs with and without superplasticizer specimen description compressive strength (mpa) split tensile strength (mpa) flexural strength (mpa) without superplast icizer with superplast icizer without superplast icizer with superplasti cizer without superplasti cizer with superplasti cizer fa 100 45.04 42.67 5.19 4.01 7.60 7.53 fg 80 50.37 48.89 5.19 4.95 8.40 7.73 fg 60 60.37 54.22 5.38 5.00 9.40 8.00 fg 40 47.33 60.44 3.21 5.19 5.40 8.67 fg 20 21.56 55.70 2.50 4.95 1.33 7.47 figure 4. compressive strength for ggbs blended geopolymer concrete with and without superplasticizer www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 51 published by scholink inc. figure 5. split tensile strength for ggbs blended geopolymer concrete with and without superplasticizer figure 6. flexural strength for ggbs blended geopolymer concrete with and without superplasticizer compressive strength, split tensile strength and flexural strength for ggbs blended geopolymer concrete with and without superplasticizer are shown in figure 4 to 6 respectively. upto 40% replacement of fly ash with ggbs, all strength parameters such as compressive strength, split tensile strength and flexural strength reduce with the addition of superplasticizer, when compared to geopolymer concrete without superplasticizer, due to unstability of superplasticizer in highly alkaline activator condition. beyond 40% replacement, all strength parameters increase with the addition of superplasticizer due to reduced activator to slag ratio, which agrees with the past research. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 52 published by scholink inc. 5. conclusions in this study the effect of naphthalene based superplasticizer on ggbs blended geopolymer concrete has been made. based on the experimental results, following conclusions are drawn. • workability increases with the addition of superplasticizer for all replacement levels of ggbs. maximum of 40% increase in workability is observed for 40% replacement of fly ash with ggbs. • strength properties are decreased by 20% upto 40% replacement level when superplasticizer is added. • strength properties such as compressive strength reduces by 10%, split tensile strength reduces by 20% and flexural strength reduces by 20%, when fly ash is replaced upto 40% with ggbs with the addition of superplasticizer. • strength properties are increased by 100 to 450% with the addition of superplasticizer beyond 40% replacement level of fly ash with ggbs. • fg60 i.e., 60% fly ash + 40% ggbs is the optimum blend without superplasticizer and fg40 i.e., 40% fly ash + 60% ggbs is the optimum blend with superplasticizer. references carabba, l., manzi, s., & bignozzi, m. c. (2016). superplasticizer addition to carbon fly ash geopolymers activated at room temperature. materials, 9, 586. https://doi.org/10.3390/ma9070586 fadhil, n. m., demie, s., fareed, a. m., & shafiq, n. (2011). effect of superplasticizer and naoh molarity on workability, compressive strength and microstructure properties of self-compacting geopolymer concrete. international journal of civil and environmental engineering, 3(2), 122-129. laskar, a. i., & bhattacharjee, r. (2012). effect of plasticizer and superplasticizer on workability of fly ash based geopolymer concrete. proceedings of international conference on advances in architecture and civil engineering (aarcv 2012), 21st-23rd june 2012. lloyd, n., & rangan b. v. (2009). geopolymer concrete; sustainable cementless concrete (pp. 33-54). proceeding of the 10th aci international conference on recent advances in concrete technology and sustainability issues , seville, acisp-261. nematollahi, b., & sanjayan, j. (2013). effect of superplasticizers on workability of fly ash based geopolymer (pp. 713-719). in ciec 2013, proceedings of the international civil and infrastructure engineering conference. https://doi.org/10.1007/978-981-4585-02-6_61 nematollahi, b., & sanjayan, j. (2014). effect of different superplasticizers and activator combinations on workability and strength of fly ash based geopolymer concrete. materials and design, 57, 667-672. https://doi.org/10.1016/j.matdes.2014.01.064 https://doi.org/10.3390/ma9070586 https://doi.org/10.1007/978-981-4585-02-6_61 https://doi.org/10.1016/j.matdes.2014.01.064 www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 53 published by scholink inc. nematollahi, b., & sanjayan, j. (2014). efficacy of available superplasticizers on geopolymers. research journal of applied sciences, engineering and technology, 7(7), 1278-1282. https://doi.org/10.19026/rjaset.7.420 patankar, s. v., ghugal, y. m., & jamkar, s. s. (2015). mix design of fly ash based geopolymer concrete. in advances in structural engineering (pp 1619-1634). springer india. https://doi.org/10.1007/978-81-322-2187-6_123 xie, j. t., & kayali, o. (2015). effect of superplasticizer on workability enhancement of class f fly ashbased geopolymers. 2015 world of coal ash(woca) conference in naschille, tnmay 5-7. https://doi.org/10.19026/rjaset.7.420 https://doi.org/10.1007/978-81-322-2187-6_123 study on effect of superplasticizer on ggbs blended geopolymer concrete abstract geopolymer concrete is an alternate to conventional concrete with reduced carbon emission, embodied energy and global warming potential and transforming waste product into an useful material. geopolymer concrete is produced by mixing highly alkaline a... keywords ground granulated blast furnace slag(ggbs), fly ash, superplasticizer, blended geopolymer concrete 1.1 general concrete is the widely used material in the world after water. ordinary portland cement has been used traditionally as a binding material for preparation of concrete. the world-wide consumption of concrete is believed to rise exponentially for the inf... geopolymer concrete is highly viscous or sticky in nature, which reduces the workability. to increase the workability, extra water or superplasticizer will be added. therefore, the present work aims to study the effect of adding superplasticizer on wo... 1.2 constituents of geopolymer concrete geopolymer concrete can be manufactured by using the low-calcium fly ash obtained from coal-burning power stations. most of the fly ash available globally is low-calcium fly ash formed as a by-product of burning anthracite or bituminous coal. although... the main constituents of the geopolymer concrete are source materials and alkaline liquids. the source materials should be rich in silicon (si) and aluminum (al), these could be natural materials such as kaolin, clays etc. alternatively, by-product ma... 3.1 materials 3.2 mix proportions as there are no codal provisions for the mix design of geopolymer concrete, the geopolymer concrete mix was prepared as per the procedure given by patankar et al. the alkaline liquid to fly ash ratio is kept as 0.35. the ratio of sodium hydroxide to s... table 2. quantity of ingredients of m30 geopolymer concrete 3.3 casting and curing fine aggregate, coarse aggregate, fly ash are mixed in dry condition for 3-4 minutes and then the alkaline solution, which is a combination of sodium hydroxide solution and sodium silicate solution with superplasticizer dosage of 3% by weight of bindi... references microsoft word ees-v2n2-p54.doc energy and earth science vol. 2, no. 2, 2019 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 54 the investigation on rheology and microstructure for lithium complex grease mao jingjing1*, li jianming1, qiu jianwei1, liu lijun1, wang yue1 & zhang lijiuan1 1 petrochina lanzhou lubricating oil r&d institute, lanzhou, china * mao jingjing, e-mail: maojingjing_rhy@petrochina.com.cn received: july 25, 2019 accepted: august 20, 2019 online published: september 4, 2019 doi:10.22158/ees.v2n2p54 url: http://dx.doi.org/10.22158/ees.v2n2p54 abstract the rheological characteristic parameters of five lithium complex lubricating greases were determined. the comparison of rheological characteristic parameters and microstructure of the five greases was made. the results showed that the knowledge of the rheological properties of lubricating greases may contribute to reflect the change of the thickener structure. the flow transition index characterized the breaking behavior of inner structure of grease, the greater this index, the better that soap fiber structure of grease; the damping factor was shifted from a medium range towards a lower value which resulted in brittle character of sample. at a constant shear rate, the soap fiber structure of complex lithium grease is dense and uniform, apparent viscosity decline rate is small. in this sense, it is relevant to understand how the development of the soap fiber structures in the grease contributes to several functional and rheological properties of lubricating greases. keywords lithium complex grease, rheological property, viscoelasticity, microstructure 1. introduction the rheology of grease refers to the flow and deformation characteristics of grease when subjected to shear stress. grease is a colloidal structure with significant non-newtonian fluid properties. it can maintain a certain shape like a solid when it is not subjected to shear stress, that is, it will not flow when it is at rest. when subjected to weak shear stress, it will be elastically deformed; after removing shear stress, it can return to its original position and shape, exhibiting the elastic properties of the solid. when the applied shear stress is large enough, the grease deforms and flows, and thus can no longer automatically return to the original position and shape, so the starting torque of the grease in the machinery is larger than that of the liquid lubricating oil. during the flow of the grease, as the shear stress increases, the soap fibers are aligned, which reduces the apparent viscosity of grease. in the case of extremely high shear stress, the grease flows like a newtonian fluid, and the www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 55 published by scholink inc. viscosity remains constant and does not change with the shear rate. the rheological properties of the grease are directly related to the microstructure of the system and the interaction between the internal materials, and are the macroscopic representation of the internal microstructure of the system. therefore, studying the rheology of grease is of great significance for the production and application of grease. in recent years, more and more researchers have used different methods to study the rheological properties of grease. meng et al. studied the rheological properties of lithium grease based on thixotropy at different shear rates, different time and different temperatures. the rheological model with structural parameters was fitted from the experimental results. the model can describe the yield stress, shear dilution and thixotropy of the tested grease. guo et al. studied the rheological properties of semi-fluid lithium grease and complex lithium grease at different consistency and temperature, and discussed the effects of the type, content, temperature and shear rate of thickeners on their rheological properties. wang et al. studied the effects of structure and content of thickener, temperature, base oil viscosity and shear time on rheological parameters were investigated by haak rheometer. the results show that the strength limit of grease decreases with the increase of temperature, but the change of plastic viscosity and plastic index is irregular. delgado et al. studied the relationship between rheological properties and microstructures in the preparation of lithium grease. j.m. franco et al. studied the mixed rheological properties in the production of grease. j.e. martin-alfonso et al. studied the effect of a polymer on the rheological properties of greases. yeong et al. studied the steady flow and viscoelasticity of greases with different thickener content. however, the test instruments and methods used by researchers are different, and the rheological performance test results are also described in different ways. the research contents are mainly focused on thixotropy, yield stress and apparent viscosity of lubricating grease rheology. the viscoelastic characteristic parameters of lubricating grease and their relationship with microstructure have not been reported. in 2007 and 2011, the german standard revised and published the din 51810-1 “determination of the shear viscosity of greases using a rotational viscometer—part 1: cone and plate inspection systems”, din 51810-2 “determination of lubrication rheological properties—part 2: determination of the flow point using an oscillating rheometer with a parallel plate detection system. the standard specifies the test methods and conditions for grease rheology, but the standard is not used to describe how the test results should be understood and applied. in addition, therefore, this paper applies and discusses the standard method through literature and data accumulation. the rheological tests of several lithium complex grease samples were carried out, and the test results were analyzed. the microstructure of the samples was compared with the samples. it is believed that by testing the rheological parameters of lubricating grease, it has certain guiding significance for the development and application of grease products. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 56 published by scholink inc. 2. experiment part 2.1 test equipment the electron micrograph was taken by a field emission scanning electron microscope (fe-sem) manufactured by jeol, model number jsm-6701f. the rheology test uses anton paar’s mcr301 rheometer with air bearings, motors and optical encoders. it can be extended to different temperature control units with control stress and control rate functions. the oscillating mode experiment used a parallel plate test system with a diameter of 25 mm. the rotation mode experiment used a cone and plate test system with a diameter of 25 mm and an angle of 1.0 °c. test temperature accuracy ± 0.1 °c. 2.2 test methods refer to din 51810-1 and din 51810-2. 2.3 preparation and performance of grease samples the base oil and 12-hydroxystearic acid were added to the kettle and stirred, and the mixture was heated to 80 °c to dissolve. after 90-100 °c, a lithium hydroxide aqueous solution was added and saponified for 2 hours. dehydrated at 130 °c for 1 h. the aqueous solution of lithium hydroxide and azelaic acid was added to carry out a reaction for 1 hour, and the mixture was heated to 160 °c for 1 hour, and then the remaining base oil was added, and the temperature was raised to 210 °c for 10 minutes. final cooling, addition of additives and homogenization. the properties of the five samples are shown in table 1. samples 1 and 2 were commercial greases products, and the others were laboratory prepared samples. table 1. basic properties of five lithium complex grease test items sample1 sample 2 sample 3 sample 4 sample 5 test methods worked penetration/0.1mm 279 232 213 256 225 iso 2137 prolonged worked penetration /0.1mm 295 250 233 272 267 iso 2137 dropping point/℃ 304 275 317 316 315 iso 6299 oil separation /% 2.52 0.5 0 3.02 2.31 astm d6184 3. results and discussion 3.1 comparison of microstructure the microstructures of the five lithium complex grease samples were compared, and the electron micrographs of the photographs are shown in figure 1. it can be seen from the figure that the soap fiber network structure of the five samples has obvious differences. the soap fiber of sample 1 is slender, the diameter is the most uniform, and almost all the fibers exhibit a clear double helix-like structure, the whole fiber network is dense and interlaced. the fiber morphology and regularity of samples 2 and 3 were slightly worse than those of sample 1, and there were relatively coarse fibers. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 57 published by scholink inc. the soap fiber of sample 4 was uneven in diameter and length, and part of the soap fiber had no double helix structure. sample 5 had the worst morphology of soap fibers, loose network structure, different diameter and length of soap fibers, and lumpy and flaky soap fibers. the difference in microstructure of the lithium complex grease sample will result in a change in macroscopic rheological properties. sample 1 sample 2 sample 3 sample 4 sample 5 figure 1. sem photograph of five lithium complex greases 3.2 comparison of viscoelasticity grease is a semi-solid material that is both viscous and elastic. the oscillating experiments of five lithium complex grease samples were carried out by rheometer, and the relationship between the storage modulus g’ and the loss modulus g’’ as the shear stress increased was obtained, as shown in figure 2 and figure 3, the storage modulus g’ represents the elastic part of the viscoelasticity of the grease, indicating that the stress energy is temporarily stored in the test and can be recovered. the loss modulus g' represents the viscous portion of the viscoelasticity of the grease, indicating that the energy used for the initial flow is an irreversible loss and the energy is converted to shear heat. at 25°c and -40°c, the modulus of the five samples decreased with the increase of stress. when the stress is small, g’ is greater than g’’, indicating that the samples have more similar structural features to solids. the point at which the storage modulus g’ begins to decrease is usually defined as the end point of the linear viscoelastic region (lve), which determines the maximum deformation that the sample can withstand before the www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 58 published by scholink inc. internal structure is destroyed. the shear stress τy at this time is also called yield point. in the linear viscoelastic region, the grease has gel characteristics, physical or chemical cross-linking network structure, g’ and g’’ can characterize the structural strength and viscosity of the grease, and thickener is the main factor affecting the structure of grease. it can be seen from figure 2 that the modulus values of the five samples with higher consistency at normal temperature are also higher, and the corresponding yield stress τy is also larger, which is consistent with the actual use of the grease. when the mechanical parts rotate, generally grease with a thicker consistency require a larger external force to deform, so the rotational torque is also higher. as the shear stress increases, the modulus decreases. when the shear stress τ>τy, the sample enters the yielding zone. the soap fiber structure of the lithium complex grease begins to be destroyed, and the soap fibers begin to be rearranged, but at this time the sample still has gel characteristics, only partial deformation can be recovered; at higher shear stress, the lines g’ and g’’ intersect at one point, also known as the flow point, the stress at g’=g’’ is taken as the flow stress τf, indicating that the sample begins to flow at this time, and the fiber network structure of the lithium complex grease is greatly destructed, when the shear stress τ>τf, the viscosity characteristic of the sample is greater than the elastic characteristic, g’’>g’, indicating that the sample is in a liquid state and exhibits flow behavior. figure 2. the storage and loss modulus for greases（25℃） 10 2 10 3 10 4 10 5 10 6 pa g' g'' 1 10 100 1,000 10,000pa shear stress  sample 1 sample 1[lve-r] sample 1[flow point] sample 2 sample 2[lve-r] sample 2[flow point] sample 3 sample 3[lve-r] sample 3[flow point] sample 4 sample 4[lve-r] sample 4[flow point] sample 5 sample 5[lve-r] sample 5[flow point] www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 59 published by scholink inc. figure 3. the storage and loss modulus for greases（-40℃） the calculated viscoelastic characteristic parameters are shown in table 2 and table 3. the stress value τf of the flow point is one of the important characteristics of the grease, and has significance in the application of the grease. the flow stress of the five samples at -40°c was significantly increased compared with 25°c, indicating that the fluidity of the lithium complex grease deteriorated at low temperatures. comparing sample 2 and sample 3 with close consistency, it was found that the flow stress of sample 3 was much higher than that of sample 2 at -40°c, indicating that the low temperature fluidity of sample 2 was better. the flow transition index τf/τy is also an important rheological characteristic parameter, which can describe the failure behavior of the internal structure of grease. the closer the value is to 1, the more the grease exhibits brittleness, and the soap fibers are more susceptible to breakage when sheared. it can be seen from table 2 that the τf/τy of the five samples differs greatly at 25°c, and the τf/τy value of the sample 1 is the largest, indicating that the soap fiber structure is the most stable and tough, compared with the electron micrograph in figure 1, the soap fiber of sample 1 has the most uniform morphology and the most compact network structure. the τf/τy values of sample 2 and sample 3 are relatively close, and the morphology and uniformity of the soap fibers are similar in terms of microstructure. the τf/τy value of sample 4 was much lower than that of sample 1, and the corresponding microstructure was also significantly deteriorated, indicating that the soap fiber structure was more easily destroyed and the stability was poor when sheared by stress. the τf/τy value of sample 5 was the smallest, and the grease structure was most easily destroyed. compared with the microstructure, the soap fiber morphology of sample 5 was also the worst. therefore, comparing the flow transition index τf/τy of five samples at room temperature and the structure of soap fiber, it is found that there is a certain relationship, and the poorer the morphology of the soap fiber structure, the smaller the value of τf/τy. it can be seen from table 3 that the grease will become hard and brittle at -40°c due to the extremely low temperature, and the τf/τy values of the five samples are significantly reduced and the difference is not large. it is indicated that the flow transition index τf/τy of the lithium complex grease can be tested at room 10 3 10 4 10 5 10 6 10 7 pa g' g'' 10 100 1,000 10,000 100,000pa shear stress  sample 1 sample 1[lve-r] sample 1[flow point] sample 2 sample 2[lve-r] sample 2[flow point] sample 3 sample 3[lve-r] sample 3[flow point] sample 4 sample 4[lve-r] sample 4[flow point] sample 5 sample 5[lve-r] sample 5[flow point] www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 60 published by scholink inc. temperature, which can better reflect the stability of the internal structure of the sample. in addition, the loss factor or damping coefficient tan δ=g’’/g’ can also be used as an added value for grease performance description. the loss coefficient values in the linear viscoelastic region are shown in table 2 and table 3. the small loss factor value indicates that the sample is brittle and the loss factor is large, indicating that the sample is easier to spread. it can be seen from table 2 that the sample has the largest tanδ value at room temperature, and the soap fiber is finer and uniform in terms of microstructure, so that it is easier to spread and enter the raceway surface. the tanδ values of sample 2, sample 3, and sample 4 were substantially at one level. sample 5 has the smallest tanδ value, and its soap fiber structure is also the worst. the uneven soap fiber makes it difficult to enter the raceway, and the sample is brittle. at -40°c, the tan δ values of the five samples increased to different extents, indicating that the brittleness of the grease became larger at low temperatures, but the relationship between the tan δ value and the microstructure of the sample was not obvious, indicating the rheology of grease is not only related to thickeners, but also factors such as base oil at low temperature. table 2. viscoelastic characteristic parameters for lithium complex greases（25℃） viscoelastic characteristic parameter sample number 1 2 3 4 5 yield point τy /pa 33.2 79.1 178 83.5 335 flow point τf /pa 809.5 1238 2192 616.1 1873 flow transition index τf/τy 24.38 15.65 12.31 7.38 5.59 loss factor tanδ 0.311 0.233 0.236 0.258 0.135 table 3. viscoelastic characteristic parameters for lithium complex greases（-40℃） viscoelastic characteristic parameter sample number 1 2 3 4 5 yield point τy /pa 10200 562 3720 3070 571 flow point τf /pa 35570 1814 23390 10470 1926 flow transition index τf/τy 3.49 3.23 6.29 3.41 3.37 loss factor tanδ 0.345 0.3745 0.2595 0.407 0.473 3.3 comparison of shear viscosity viscosity is a property of a material that undergoes flow and irreversible deformation under stress. the relationship between the shear stress τ of newtonian fluid and the shear rate  is =    . while the grease is a non-newtonian fluid, the shear stress and shear rate are not proportional, so the shear viscosity η can only be determined under the specified test conditions. the viscosity of the five lithium complex grease samples was measured at a constant shear rate as shown in figure 4. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 61 published by scholink inc. figure 4. the shear viscosity changes for lithium complex greases since the grease is a shear-thinning fluid, the viscosity of the five samples decreased slightly under constant shear at 5 minutes. the initial viscosity a and the final viscosity e in the test period and the viscosity decrease rate rel are recorded from the graph, and are calculated according to the equation 100a e rel a       , expressed in units of percentage. as shown in table 4, it can be seen that the viscosity drop rate of the sample 1 is the smallest, and a certain viscosity can be maintained after shearing, and the soap fiber structure is the most stable. the viscosity reduction rates of sample 2, sample 3, and sample 4 were substantially at one level, and the stability of the soap fiber structure was not much different. the viscosity of the sample 5 decreased the fastest, and the viscosity decreased by nearly half after 5 minutes of shearing, indicating that the shear resistance was poor. therefore, the denser and more uniform the soap fiber structure of the lithium complex grease, the better the viscosity is maintained during the shearing process, and the poorer the soap fiber structure, the faster the viscosity decreases during shearing. if the viscosity drops too fast during use, it will be lost or smashed, which will eventually lead to lubrication failure. table 4. the shear viscosity for lithium complex greases shear viscosity sample number 1 2 3 4 5 initial viscosity ηa /pa·s 4.54 6.14 6.90 3.51 5.57 final viscosity ηe /pa·s 4.35 5.38 5.91 3.14 3.09 relative viscosity drop rate ηrel /% 4.17 12.3 14.3 10.5 44.5 4. conclusion (1) by determining the rheological characteristic parameters of the grease, the stability and the degree of damage of the lithium complex grease structure can be described, which has certain guiding significance for the development and use of the product. the rheological properties of lithium complex greases are related to the microstructure of the grease and are the macroscopic representation of the internal 1 10 pa·s  5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10min t sample 1 sample 2 sample 3 sample 4 sample 5 www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 62 published by scholink inc. microstructure of the grease. the lithium complex grease with excellent performance should have a dense and uniform, staggered three-dimensional network structure, and the soap fiber exhibits a distinct double helix structure. (2) the viscoelastic characteristic parameters are related to the microstructure of the grease. the flow transition index τf/τy is an important rheological characteristic parameter that can describe the failure behavior of the internal structure of the grease. the poorer the soap fiber structure of the lithium complex grease, the smaller the value of τf/τy, indicating that the soap fiber is more likely to break under the action of shearing force. the loss factor tan δ can be used as an added value for grease performance description. the hourly loss factor indicates that the sample is brittle and the loss factor is large, indicating that the sample is easier to spread. (3) at a constant shear rate, the denser and more uniform the soap fiber structure of the lithium complex grease, the better the viscosity is maintained during shearing, the smaller the relative viscosity drop rate, and the worse the soap fiber structure. the faster the viscosity decreases during the shearing process, the greater the rate of decrease in relative viscosity. references delgado, m. a. et al. (2005). relationship among microstructure, rheology and processing of a lithium lubricating grease. chemical engineering research and design, 83, 1085-1092. https://doi.org/10.1205/cherd.04311 din51810-1. (2007). determination of the shear viscosity of greases using a rotary viscometer—part 1: cone-plate inspection system. germany: german standardization association. din51810-2. (2011). determination of the rheological properties of greases—part 2: determination of the flow point using an oscillating rheometer with a parallel plate detection system. germany: german standardization association. franco, j. m. et al. (2005). mixing rheometry for studying the manufacture of lubricating greases. chemical engineering science, 60, 2409-2418. https://doi.org/10.1016/j.ces.2004.10.042 jiang, m. j. et al. (1998). study on the rheological properties of grease: ii. the flow of grease in the tube. lubrication and sealing, 23(4), 63-65. jiang, m. j., guo, x. c., & jiang, b. x. (1997). study on the rheological properties of semi-fluid fat. synthetic lubricating materials, 2, 6-10. martin-alfonso, j. e. et al. (2009). influence of soap/polymer concentration ratio on the rheological properties of lithium lubricating greases modified with virgin ldpe. journal of industrial and engineering chemistry, 15, 687-693. https://doi.org/10.1016/j.jiec.2009.09.046 meng, y g., & zheng, j. (1998). a rheological model for lithium lubricating grease. tribology international, 31(10), 619-625. https://doi.org/10.1016/s0301-679x(98)00083-8 wang, x. l., zhu, t. b., & liang, h. f. (1997). determination and research of rheological parameters of domestic grease. journal of tribology, 17(3), 232-237. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 63 published by scholink inc. yeong, s. k., luckham, p. f., & tadros, t .f. (2004). steady flow and viscoelastic properties of lubricating grease containing various thickener concentrations. journal of colloid and interface science, 274, 285-293. https://doi.org/10.1016/j.jcis.2004.02.054 energy and earth science vol. 4, no. 1, 2021 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 21 original paper cultural inheritance and innovation—taking the heilongjiang garden design of the garden expo as an example yanxue li 1* , dawei xu 1 , shu zhu 2 , xiang zhuang meng 1 & jiefu song 1 1 school of landscape architecture, northeast forestry university, harbin, china 2 university of adelaide, adelaide, sa 5000, australia * yanxue li, school of landscape architecture, northeast forestry university, harbin 150040, china received: january 25, 2021 accepted: february 16, 2021 online published: march 17, 2021 doi:10.22158/ees.v4n1p21 url: http://dx.doi.org/10.22158/ees.v4n1p21 abstract with the rapid development of social science and technology civilization, and the acceleration of urbanization, the requirements of urban landscape planning and design are also paying more and more attention to the design concept of “adopting measures to local conditions and putting people first”. therefore, the inheritance and innovation of urban landscape planning and design based on the culture that can represent local characteristics is a respect for and inheritance of traditional regional culture, the integration of traditional culture and the culture of the new era, and the inevitable trend of modern landscape planning and development. this essay uses the heilongjiang garden engineering design project of the garden expo as a case to carry out the regional landscape planning and design, inheriting the regional characteristics, and proposing the design concept of “nature and culture growing on black soil”, integrating the characteristics of white mountains and black water into the garden, and seeing the big from the small interpret the characteristic landscape impression of heilongjiang and provide a reference for the design of the exhibition garden project in the future. keywords garden exposition, landscape planning, landscape garden, innovation with the rapid development of society, the improvement of living standards, the rapid development of urban construction, and the deteriorating ecological environment, people’s demand for high-standard urban landscape planning and design have become more and more obvious. due to the different natural environments in various regions, various urban landscapes will be produced according to local conditions, and the design based on regional culture can fully reflect the evolution of the local historical, cultural and social structure. especially in the rapid development of science and technology www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 22 published by scholink inc. in the contemporary era, it brings together contemporary science and technology and design concepts, integrates the local natural environment, customs, folk customs and historical context, and designs a livable in a way of inheriting the past, combining the contemporary, and innovating the future. the urban landscape is an inevitable trend in the development of urban landscape design. because of this, an urban landscape planning and design concept and method that combines the integration and innovation of contemporary technology and culture with the background of regional cultural characteristics are indispensable. as a high-level platform for the centralized review of the landscape architecture industry in my country, the garden expo, excellent teams from all over the country are doing their best to present the best exhibition garden works to the public, each with its characteristics and benefits. as an important part of the garden expo, the city exhibition garden strives to display the local natural features, folk customs, and historical and cultural feelings within a limited space, so that visitors can realize the local characteristics of the city and truly serve as a window for the transmission of regional information. and the city exhibition garden also has a preliminary role in promoting the image of the city. as one of the city attractions exhibition parks, heilongjiang garden has won the design award, plant configuration award, and construction award of this year’s garden expo. it shows the regional cultural characteristics of heilongjiang with its unique cultural design and technology. the cultural inheritance and innovative design concepts and methods used in the process of garden ecological landscape design are worthy of our reference. also, after long-term management and cultivation, the level of plant communities in the exhibition garden has grown well, and both ecological and landscape environmental benefits have been obtained. it played well. this paper takes the landscape planning and design of the heilongjiang garden of the international garden expo as an example to analyze the application of the design concept of “regional cultural creation, inheritance and innovation” in actual projects, and make theoretical and practical references for future urban landscape planning and design theory and actual project research. 1. background china (chongqing) garden expo (figure 1), placed from november 2011 to may 2012, located in the longjing lake area of yuanyang town, northern new district of chongqing city, with a total elevation of about 3300 mu, composed of 21 countries and regions a collection of 127 classic exhibition gardens in 30 cities and more than 80 of them are large-scale urban parks integrating natural and human landscapes. the heilongjiang garden is located in the northern garden exhibition area of the 8th chongqing garden expo. it is hosted by the housing and urban-rural development department of heilongjiang province and co-organized by qitaihe city, jiamusi city and hailin city in heilongjiang province. the theme of this year’s garden expo is gardens, making the city more beautiful. www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 23 published by scholink inc. figure 1. tour layout of chongqing international garden expo heilongjiang province is located in northeastern china and is the province with the highest latitude in china. it is not only a synonym for cold but also a granary and tourist attraction in the northeast. it also has civilized relics and abundant resources. it is a tourist province in china, especially with heavy ice and snow. large forests, wetlands, prairies, modern agriculture, and volcanic landforms. figure 2. a) location analysis, b) adjacent garden plan, c) adjacent garden entrance space real map, and d) adjacent garden real map www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 24 published by scholink inc. heilongjiang garden is located in the northern garden exhibition area of the international garden expo park, with an area of 1754 m2 and a relatively flat terrain (figure 2a). the design expresses the essence of the garden’s artistic conception with the special humanities and natural resources in the north and highlights the rigorous visual control axis of the garden. through the contrast of black and white colors, the characteristics of the white mountains and black water are integrated into the garden, and the memory of the black soil is reminded. 2. planning and design ideas the heilongjiang garden takes “mo yuan longjiang, ecological fertile soil” as its design theme, and its concept of “nature and culture growing in black soil”, which interprets heilongjiang’s characteristic landscapes of ice and snow, large forests, prairies, and large wetlands. in chinese, the word “mo” is composed of “black” and “land”. the black land is synonymous with heilongjiang and a unique treasure in china. and mo means black, and black gold such as oil and coal is abundant in this vast black land. the word “yuan” means the vast “sanjiang plain”. the three great rivers converge and accumulate to form this fertile soil. the ecologically fertile soil has nurtured the multicultural and characteristic humanities and customs of the longjiang land. the exhibition-themed buildings are used as the main scenery. the four characteristics of heilongjiang are reflected in the small and large, namely “big ice and snow”, “big forest”, “big wetland” “prairie” ecological characteristic landscape impression. 3. overall layout and innovation overall layout: the overall layout is designed with the unique characteristics of longjiang’s natural and human resources as clues, focusing on the coordinated relationship of space, and the entire garden is within easy reach using natural layout and traditional chinese gardening art techniques to integrate gardens and culture. as a whole, combined with the topography, landforms and the theme of this year’s garden expo “gardens, make life better!”, it displays the characteristics of heilongjiang’s ice and snow, forests, grasslands, and wetlands. the natural and cultural resources of the country are organically combined to create a unique picture of northland scenery. functional planning: taking heilongjiang's unique humanities and natural resources as clues, the whole park will comprehensively display heilongjiang’s characteristic buildings and ecological landscapes through different themed spaces and system evolution relationships (figure 3). the whole park is divided into four major functional areas, namely the theme building main scenic area, ecological forest area, wetland education park, and wilderness scenery area. the main attractions include “forest snow house”, “boiling below zero”, “longyin”, “snow castle”, “birth forest green creek” and “black soil blessed land”. www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 25 published by scholink inc. figure 3. (a) functional zone, (b) traffic analysis, (c) line of sight analysis and (d) lighting layout 3.1 theme building main scenic area the theme building “forest snow house” is the heilongjiang cultural exhibition hall (figure 4(ab)). the architectural form adopts a low-rise structure and the shape is made of raw wood materials. it is a characteristic of heilongjiang. the style and characteristics of wooden houses reflect the regional characteristics of heilongjiang. the use of low-level structure and log materials to refine and sublimate modern heilongjiang wooden residential elements. the wall of the building facing the population of the exhibition garden is black and white, reflecting the unique northern scenery of the linhai snow plain, and the roof is in the form of thick snow. the “dragon yin” abstract black dragon style at the entrance of the whole garden serves as a point of view. it means the auspicious dragon takes off. the character “dragon” composed of five-color grasses, a characteristic plant in the north, is agile, generous, and natural, which means the dragon river takes off and plays a role of the spotlight. the wall facing the building is a black and white pattern, which plays the role in the topic. the roof of the building is made of white optical fiber material to form a thick snow form, reflecting the natural and simple regional characteristics of heilongjiang’s “big ice and snow”. the enclosed form creates a waterfront courtyard space experience; the “boiling below zero” scenic spot (figure 4 cd), “zero degrees” refers to the cold, and “zero degrees” reflects the characteristics of cold regions and the smoky atmosphere of life in the northern winter. the scenic spot takes the black wall as the background and the white birch trunk as the foreground. the contrast of black and white echoes the main architectural landscape. the columnar water flows out slowly, and the www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 26 published by scholink inc. mist formed is floating in the garden, misty and vague, like a boiling momentum, with a unique taste, which implies the vitality and passion of longjiang people. this area embodies the regional characteristics of heilongjiang’s “heavy ice and snow” and “big forest”. figure 4. (a) the large-scale design plan of the theme building wall mural, (b) the real scene of the theme building wall after the construction is completed, (c) the design effect drawing of the “boiling under zero” scenic spot and (d) the “under zero” “boiling” scenic spot after construction 3.2 ecological forest area the dynamic and quiet landscape atmosphere is even more lingering. the natural and wild walks shuttle through the forest to form a sheltered place, creating a quiet and comfortable space. the gurgling stream shuttles under the forest and the river rocks are scattered around the stream, creating a picture scroll that integrates nature, ecology, humanities, and landscape. at the “birch forest and green creek” scenic spot, the smart water body constantly changes its posture, running through the entire exhibition garden, creating a series of interesting spaces for enjoying the water and being hydrophilic. the stream runs through the birch forest, and the river rocks are scattered around the stream to create a quiet and comfortable space. gorgeous aquatic and wet plants grow on the banks of the gurgling stream, creating a picture scroll that integrates nature, ecology, humanities and landscapes, becoming a missionary garden that showcases the biodiversity of the sanjiang wetland; the “black soil and blessed land” attraction (figure 5) ), the red “fu” inscription, which means happiness and auspiciousness, the landscape is constructed through the winding stream combined with vigorous pine, the white and elegant birch, the elegant lilac and the rich longjiang style. the relief emphasizes the theme and fully shows the dragon. jiang chun’s unsophisticated and unrestrained black www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 27 published by scholink inc. soil style. figure 5. the real scene of the black soil and blessed land of the exhibition garden 3.3 wetland education park the agile body of water constantly changes its posture, running through the entire scenic spot, creating a series of interesting spaces for enjoying the water and being hydrophilic (figure 6(d)). on the open water, there is a “boat” for people to rest and enjoy the scenery, and people can also play barefoot in the water, which is unique. spectacular aquatic plants such as cattails, tower heads, and scallions grow on the banks of the gurgling stream, forming a characteristic landscape of the longjiang “big wetland” and becoming a public education garden that symbolizes the biodiversity of the sanjiang wetland, enabling people to understand wetlands, caring for wetlands. www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 28 published by scholink inc. figure 6. (a) the plan design of the “snow castle” in the exhibition garden, (b) the actual view of the newly built “snow castle” in the exhibition garden, (c) the actual view of the “snow castle” in the exhibition garden three years after its completion, and (d) exhibition aerial view of the park 3.4 wilderness scenic area taking full advantage of the sight control of the road, and taking into account special groups of people, the corridor adopts a barrier-free design. as shown in figure 6, “snow castle” is the main landscape sketch of the whole park. it is shaped like a pine cone. the upper part is a wooden grille, which is uneven. the lower part is made of snow-like prefabricated blocks of various sizes. the natural resources of longjiang are organically integrated with the characteristics of human resources. the wudalianchi volcanic rocks cover the ground, revealing simplicity, ruggedness and natural no decorations, which are in harmony with the “snow castle” building and the surrounding environment. the vigorous pine, the white and elegant birch, and the simple and elegant lilac, together with the dry reeds, form the scenery of the northern country in the south of the saijiang river. 3.5 plant and sketch design garden plant landscaping emphasizes the beauty of form, diversity and unity, and the beauty of artistic conception. the landscaping method also uses the borrowing method to combine the local native tree species with the regional characteristics to ensure the sustainability of the plant landscape. www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 29 published by scholink inc. according to the characteristics of the humid tropical monsoon climate in chongqing, the seasonal landscape changes are considered as a whole for the whole park to achieve the effect of four seasons (figure 6(d)). the selection of tree species is based on native tree species such as osmanthus fragrans and podocarpus eryngii, fully considering the color and shape of plants, emphasizing the seasonal changes of plants, and planting them in a reasonable combination; the plant space landscape construction is based on different topographic characteristics for planting. in the limited space, to reflect the regional characteristics, the northeast characteristic tree species white birch is combined with the aquatic plants with high ornamental value, and its aesthetic value is displayed in the landscape and ecosystem (the plant selection is as dry umbrella grass, celandine, lotus, etc.); small items such as signs, trash cans, etc., are designed according to the theme. the selection of materials not only pays attention to ornamental but also pays attention to functionality. mainly scattered light, set up different types of lawn lights, underwater lights, color-changing lights, rare earth nano lights, etc. 3.6 features and innovation the heilongjiang exhibition garden, combined with site conditions, uses a limited space to fully demonstrate the unique local characteristics, promote the development of the local and surrounding areas, and provide citizens with a good outdoor recreational place. the main features and innovation are combined as follows: (1) the construction concept of the unique regional cultural landscape is novel and unique. through in-depth research and analysis of the current situation of the heilongjiang exhibition park, the design is carried out from a unique perspective. the concept is unique and innovative, which fully demonstrates the cultural connotation of heilongjiang and the ecological characteristics of the north, allowing tourists from all over the country to have a more direct and appropriate understanding of heilongjiang’s characteristic regions features. (2) innovation of material expression. while the landscape design method integrates regional characteristics, culture and space treatment, the organic components of landscape design such as the boiling below zero, the snow castle and the thick snow on the roof of the main building, pay attention to the new materials, technology and craftsmanship. innovate, and make the limited space bigger, form a good spatial relationship and a good application of new materials. (3) to form a regionalized natural landscape, the regional characteristics must be respected. through tracking and attention, we boldly tried and innovated the introduction of characteristic plant varieties. besides, we followed the laws of nature, respected regional characteristics, adapted the trees to the site, and adopted measures to local conditions to form a good localized natural landscape. garden makes life better! combining with promote the improvement of the quality of urban landscaping and the development of horticulture across the country, promote the use of new materials, new techniques, and new concepts in landscaping, explore and practice new ways to organize market-oriented meetings, and guide the society to pay attention to the future harmonious human settlement environment through the construction of this project, we will improve the ecological www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 30 published by scholink inc. environment of the city and improve the quality of people’s living environment. at the same time, it can promote the development of the national landscape design industry. man is closer to nature and more harmonious with nature. 4. conclusion this article mainly introduces the concept of “regional cultural inheritance and innovation” into urban landscape planning and design. first of all, in the context of regional cultural heritage and innovation, analyze the overall conceptual design layout, mainly from the natural ecosystem environment; second, analyze the overall spatial layout of the landscape, mainly from the two aspects of local natural resources and human resources analysis and integration; thirdly, under the concept of regional cultural inheritance and innovation, further specific design principles for the landscape planning and design of the garden expo, design techniques, and design schemes provide a theoretical and practical basis for the landscape planning and design methods of the garden expo park. besides, this design fully embodies that the inheritance and innovation of modern garden design should focus on the development direction of modern urban construction, and at the same time combine the science and technology of the times and the regional cultural characteristics to shape its own regional cultural image characteristics. this design also provides a direction for the development of modern garden design and construction. acknowledgement support by natural science foundation of heilongjiang province: research on the protection and development of rural landscape forms in heilongjiang province (jj2018qn0681). references fan, q. (2016). narration of featured landscapes for urban culture. in e. mcanally et al. (eds.), proceedings of the 2016 international conference on arts, design and contemporary education (pp. 734-737). https://doi.org/10.2991/icadce-16.2016.177 li, l., & huang, s. l. (2015). functions and plant configuration of wuhan jiangtan park. journal of landscape research, 7(05), 41-44. li, z. x. (2014). application of plants in chinese garden landscape, 10(5), 143-145. liang, j., & zhou, y. (2017). preliminary study on urban street landscape design under regional cultural background based on yuanlin road, jingzhou city. in e. mcanally et al. (eds.), proceedings of the 2017 international conference on art studies: science, experience, education. liu, h. (2017). status analysis and vision on urban landscape planning-take chengdu city as an example. in z. you, z. tan, & j. ke (eds.), 2nd international conference on materials science, resource and environmental engineering. https://doi.org/10.1063/1.5005231 https://doi.org/10.2991/icadce-16.2016.177 https://doi.org/10.1063/1.5005231 www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 31 published by scholink inc. yan, x., guo, l., & jiang, y. (2016). an analysis on regional culture in city street landscape design (pp. 605-608). issgbm international conference on information, communication and social sciences. yu, z. (2018). urban garden planning and design and ornamental plant protection. journal of landscape research, 10(04), 162-165. zhao, z., & hu, x. j. (2014). urban river landscape design based on regional characteristics—a case study of jinxi river in hushan town. journal of landscape research, 6(z1), 13-16+19. zhou, x. d. et al. (2014). research on the design of community landscape planning under eco-house perspective. applied mechanics and materials, 716-717, 541-544. https://doi.org/10.4028/www.scientific.net/amm.716-717.541 zhu, z. j. (2011). analysis of heilongjiang province village traveling present situation and problem (pp. 146-152). intelligent information technology application association. education and management(isaebd 2011 ccis 210). intelligent information technology application association: institute for the application of intelligent information technology. https://doi.org/10.4028/www.scientific.net/amm.716-717.541 energy and earth science vol. 5, no. 4, 2022 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 29 original paper assessment of microbial air quality of nashik city with particular reference to mucorales fungi, and in vitro evaluation of two triazole antifungal drugs against the prevalent mucor species borkar, s. g. 1* , ajayasree, t. s. 1 & riddhi damale 1 1 soil, seed, plant disease diagnostic and research centre, endeavour scientific agriculture, 103, prestige point, in front of nashik road police station, nashik 422 101, india * borkar, s. g., e-mail: borkarsg@yahoo.co.in received: september 30, 2022 accepted: october 31, 2022 online published: november 24, 2022 doi:10.22158/ees.v5n4p29 url: http://dx.doi.org/10.22158/ees.v5n4p29 abstract air pollution particularly that of particulate matter (pm 2.5, pm 2.10), carbon monoxide, ozone, nitrogen dioxide, sulfur dioxide, ammonia, lead, and air microbial contaminants, has serious consequences on human health. air pollution in metros and cities around the world is measured for the above parameters except for the microbial air contaminants. however, microbial air contaminants are important sources of microbial infection in humans and particularly airborne fungi are known to cause diseases like aspergillosis and mucormycosis in immunocompromised patients which are about 160 million in the world. in the year 2021, mucormycosis disease was reported as a post-covid infection in several states of india as a fatal disease caused by a black fungus (mucor) prevalent in the atmospheric air. in the present study, we assessed the microbial air quality (colony forming unit of microbes/m 3 of air) of nashik city air, in india, for its microbial contaminant, particularly mucor sp., and further the prevalent mucor sp. was evaluated for its reaction to two triazole antifungal drugs viz. itraconazole and fluconazole available in medical stores. the air quality index of 90 cfu/tidal volume for mucor species was regarded as safe, based on the studies. both the triazole drugs at their active ingredient concentration (1000 µg/ml) were unable to check the growth of mucor fungi. the paper discussed in detail the methods for enumeration of microbial contaminant/m 3 of air and in tidal volume. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 30 published by scholink inc. keywords microbial air pollutant, mucor, mucormycosis, triazole antifungal drugs, microbial cfu/tidal volume, microbial aqi 1. introduction mucormycosis, as a post-covid infection was a serious health issue in many indian states in 2021 (borkar, 2021). the fungus responsible for this disease was a species of mucor, which is mainly present in the air. based on the anatomic localization of infection by mucor, mucormycosis can be classified as one of 6 forms viz. rhinocerebral, pulmonary, cutaneous, gastrointestinal, disseminated, and uncommon presentation (petrikkos et al., 2012). the infection of mucormycosis has serious implications with permanent disabilities like debridement of the eyes and jaws of the patients, and even death due to invasive infections (neilstone et al., 2021). generally, the infection of mucormycosis was observed in post-covid patients, with lowered immunity, or in immunocompromised patients (pak et al., 2008). the specific immunocompromised conditions include: 1) severe immunocompromised (non-hiv)-active leukemia, lymphoma, generalized malignancy, aplastic anemia, graft versus host disease, congenital immunodeficiency, solid open transplant or bone marrow transplant within 2 years of transplantation, or persons whose transplants are of longer duration but who are still taking immunosuppressive drugs. 2) chronic diseases with limited immune deficits-asplenia, chronic renal disease, chronic hepatic diseases (cirrhosis and alcoholism), diabetes, nutritional deficiencies, and people affected by pandemic diseases like covid-19 (monica & chandraprabha, 2022). at present 2% of the world population, i.e., about 160 million people are reported to be immunocompromised in the world (anonymous, 2022) and probably the targeted population for the diseases like mucormycosis caused by mucor fungus present in the atmospheric air. although the source of mucor infection is through the air, which we breathe, no documentation for this fungus in the city air quality index around the world, is available on regular basis in the metros. the air pollution in many metros and cities around the world is measured for particulate matter (pm 2.5 and pm 10), carbon monoxide (co), and other harmful gases, but nowhere it is depicted for fungal air contaminants responsible for human diseases like aspergillosis (borkar, 2020) and mucormycosis (borkar, 2021). the lack of air quality studies for harmful air microbes can be seen as a setback to keeping in check the source of infection and the optimal population threshold of the microbes in the air for human fungal infection particularly mucormycosis. therefore, in the present study, we assessed the air quality of nashik city air, in india, for its microbial contaminant particularly mucor sp. a known fungus to cause mucormycosis in humans. the mucormycosis fungi are also reported to develop resistance to the antifungal drug amphotericin-b, the most commonly used drug for its control (ellis, 2002; asghar, 2019). therefore, we evaluated two triazole antifungal drugs for their effectiveness against the mucor fungus prevalent in the nashik city air sample. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 31 published by scholink inc. 2. method 2.1 detection of microbial flora in the air sample 2.1.1 growth medium used for detection of microbial flora in air sample potato-dextrose-agar (pda) medium was used for the detection of microbial flora in the air sample. petri plates of 7.5 cm diameter having sterilized pda media were exposed to air breeze at 10 different locations in the city jurisdiction of nashik municipal corporation. these 10 locations represented the east, west, north, south, and center locality of the city. petri plates in 3 replicates/locations were used to assess the prevalence of microbes in the air at a given location. the air sample for microbial prevalence was assessed in the 2 nd week of june 2022. the maximum temperature, minimum temperature, and atmospheric humidity during the sampling period were 35 0 c, 29 0 c, and 77% respectively. the air sample was assessed for the microbial population of fungi, bacteria, actinomycetes, yeast, etc., and, particular emphasis was given to the presence of mucorales fungi in the air, as during the same period in 2021, the mucorales fungi (mucor sp. or black fungus) caused mucormycosis disease in the city patients. 2.1.2 collection of air samples on microbial growth media the microbial growth media plates were exposed to the city air of the respective location for 1-2 minutes and covered with an upper lid. such exposed plates for each location were numbered and brought to the laboratory within a period of 3 h. these plates were incubated in a bod incubator at 29±1 0 c temperature for the growth of airborne microbes trapped on the plates. reading for the growth of bacterial colonies was taken after 48 h of incubation while reading for the presence of fungal colonies was noted after 3 days onwards and up to 10 days. 2.1.3 enumeration of microbial colony forming units (cfu)/m 3 , trapped in the media plates to enumerate the colony forming unit (cfu) of each type of microbe on the growth media in a plate of 7.5 cm diameter, the simplified method was followed. the 7.5 cm diameter of the plate was earmarked length and breadthwise, as shown in figure 1, to calculate the area in cm 3 . figure 1. earmarking on microbial growth medium plates to count microbial cfu/cm 3 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 32 published by scholink inc. the earmarked length on the plate was 5.5 cm with a breadth of 5 cm, and the height (air space available) on the growth medium on the plate was 1 cm, thus giving an exposed area of 27.5 cm 3 . the microbial colonies of respective microbes viz. bacteria, fungi (mucor, aspergillus, fusarium, sterile mycelia, pilobolus, etc.), actinomycetes, and yeast contained in 27.5 cm 3 of air volume, which formed their respective colonies on growth media, were counted in the earmarked area. the number of colonies of a particular microbe obtained on this earmarked area was converted for m 3 area by employing the multiplication factor of 3.63 (100 divided by 27.5=3.63). thus, the colony forming unit (cfu) of each microbe was calculated as cfu/m 3 area. 2.2 enumeration of microbial cfu/breath and assessment of microbial air quality index conversion of m 3 to liter: 1 cubic meter is equal to 1000 liter, therefore an area of 27.5 cubic cm is equal to 0.0275 liters or 27.5 milliliters (air). during normal breathing an adult human breath around 500 ml air/breath which is known as tidal volume (hallett et al., 2021), and therefore to convert 27.5 ml of air into 500 ml of air a conversion factor of 18 (500 divided by 27.5=18) was used. thus, the number of microbial colonies obtained in a 27.5 cubic centimeter area was multiplied by 18 to get the number of cfu present per breath of air (i.e., 500 ml air). 2.3 identification of microbial colonies 2.3.1 identification of bacteria the bacterial colonies were studied for their morphology, color, elevation, shape, margin, and the gram reaction of the bacteria (borkar, 2017). the prevalence of bacterial density/m 3 air was estimated. 2.3.2 identification of fungal colonies the fungal colonies were studied for their texture, and color and were identified under a binocular microscope based on the fungal spores, structures, and fruiting bodies (funder, 1968). 2.4 in vitro evaluation of triazole antifungal drug on mucor species ten isolates of mucor species trapped on growth media from 10 locations of city air were studied for their reaction to two triazole antifungal drugs viz. itraconazole (200 mg capsule) and fluconazole (150 mg tablet), are being used for other invasive fungal infections in humans. different concentrations of these antifungal drugs viz. at 100 µg/ml; 500µg /ml and 1000 µg/ml were tested against the mucor species isolates obtained from 10 different locations. sterile pda media containing the above concentrations of these triazole drugs were prepared, poured into sterilized petri plates, and solidified. the 8 mm disc of the mucor fungal growth of individual isolate was placed, in an inverted position, on these media in petri plates. the inoculated plates were incubated in a bod incubator at 29±1 0 c temp for mucor growth/inhibition of mucor growth, and the reading was taken after 5 days of incubation. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 33 published by scholink inc. 3. results 3.1 presence of microbes in nashik city air at different locations the microbes (table 1) present and trapped in the nashik city air were mucor, aspergillus, fusarium, pilobolus, and sterile fungi among the fungal species. besides these fungal species, actinomycetes and bacterial species were also present (figure 2). no yeast/candida species were present in the air sample. on the air sample plates, the bacterial colonies appeared within 48 hrs; whereas the fungal colonies appeared after 5 days of incubation of the microbial growth media plates. among the fungal species, mucor was dominant over other fungal species with a range of 3.63 to 18.15 colony forming units (cfu)/m 3 air and differed with the locations in the city (figure 3). maximum cfu/m 3 of mucor was present in panchavati, bombay naka followed by trimbak road areas. table 1. presence of microbes in nashik city air at different locations name of location presence of microbes (cfu/m 3 ) in air mucor aspergillus fusarium actinomycetes bacteria pilobolus sterile fungi dwarka 3.63 0.0 0.0 29.04 119.79 0.0 0.0 deolali 3.63 3.63 0.0 3.63 7.26 0.0 0.0 bytco point 3.63 3.63 3.63 3.63 29.04 0.0 0.0 pandav leni 3.63 0.0 0.0 3.63 23.31 0.0 0.0 bombay naka 18.15 0.0 0.0 7.26 166.50 0.0 0.0 trimbak road (papaya nursery) 10.89 0.0 0.0 3.63 96.57 0.0 0.0 panchavati 18.15 0.0 0.0 21.78 153.18 0.0 0.0 adgao naka 7.26 0.0 0.0 83.49 126.54 7.26 0.0 nandur naka 7.26 0.0 3.63 7.26 29.97 0.0 0.0 mahsrud 7.26 0.0 0.0 10.89 156.09 0.0 7.26 the environment during air sampling: air temp max=35 0 c; min=29 0 c, rh=77%, time of sampling=3.00 pm. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 34 published by scholink inc. figure 2. microbial flora of nashik city air figure 3. trapping of air microbes at 10 locations in nashik city www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 35 published by scholink inc. the mucor species trapped in the air sample exhibited the black color mycelial growth of the fungus (figure 4) which was further purified and identified as mucor sp. based on the fungal structures. the microscopic observations exhibited the black color sporangial fruiting bodies, sporangiospores, and aggregation of black-brown thick structures of mycelial masses as debris (figure 5). figure 4. fungal colony of mucor sp. present in nashik air figure 5. microscopic fruiting bodies (sporangium) of mucor with an aggregated thick mass of fungal debris on growth media and in broth www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 36 published by scholink inc. the thick-walled fungal debris was more common besides the sporangium of the fungus in both solid (pda) media and liquid potato dextrose broth. this fungal debris contained the mycelial and spore masses (figure 6) of the mucor fungus. similar fungal structures are also reported in histopathological studies of mucormycosis infection (figure 7) (choudhary & gahlot, 2021). figure 6. spore masses turned into black thick structures in fungal growth media figure 7. aggregation of fungal hypha in mucormycosis infection among the air microbial communities, the bacterial species was most dominant and varies from 7.26 to 166.50 cfu/m 3 air. the maximum population of bacterial species was trapped in areas of bombay naka, mahsrud followed by panchavati. the bacterial species exhibited circular, raised, opaque, white, or pink colonies on growth media. the bacteria were gram-negative, cocci, and seem to be species of streptococcus. 6 7 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 37 published by scholink inc. these fungal and bacterial species survived an atmospheric temperature of 35 0 c during the may month of the summer season in the nashik city air. mucor was the dominant species among the fungal microflora in the air. the fungal species load per tidal volume (the volume of air which we breathe in a single breath) was calculated for the city air (table 2) which differed with locations in the city and for mucor fungus, it ranged from 18 to 90. table 2. presence of fungal microbes in the tidal volume of air in nashik city at different locations sr. no name of location presence of fungal spores/breath (500ml air) in city air mucor aspergillus fusarium pilobolus sterile fungi 1 dwarka 18 0.0 0.0 0.0 0.0 2 deolali 18 18 0.0 0.0 0.0 3 bytco point 18 18 18 0.0 0.0 4 pandav leni 18 0.0 0.0 0.0 0.0 5 mumbai naka 90 0.0 0.0 0.0 0.0 6 trimbal road ( papaya nursery) 54 0.0 0.0 0.0 0.0 7 panchavati 90 0.0 0.0 0.0 0.0 8 adgao naka 36 0.0 0.0 36 0.0 9 nandur naka 36 0.0 18 0.0 0.0 10 mahsrud 36 0.0 0.0 0.0 36 3.2 in vitro efficacy of triazole antifungal drug against mucor sp. prevalent in nashik city air the in vitro efficacy of two triazole antifungal drugs viz. itraconazole and fluconazole on the growth of mucor species indicated (table 3) that these drugs were ineffective against the fungus. all three concentrations, i.e., 100, 500, and 1000 µg/ml were ineffective to check the growth and sporulation of the mucor fungi (figure 8). however, in the presence of these drugs, the mycelium has a reduced growth rate on the media containing these drugs, as compared to growth on normal growth media. on the normal growth media, the mucor growth at 5 days was 7.00 cm diameter as against 1.45 to 2.77 cm on triazole-containing growth media. the percent inhibition of growth on triazole-containing media was 60.42 to 79.28 percent (table 4). www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 38 published by scholink inc. table 3. in vitro efficacy of triazole compounds against mucor sp. prevalent in nashik city air triazole compound concent ration (µg /ml) mycelial growth (in cm) of location-specific mucor isolate number average growth itraconazole (200 mg cap) containing pda media 1 2 3 4 5 6 7 8 9 10 100 1.9 2.0 1.8 1.8 1.7 1.6 1.7 2.0 1.6 1.6 1.77 500 1.7 2.0 1.5 1.9 1.4 1.5 1.6 1.8 1.7 1.7 1.66 1000 1.2 1.5 1.5 1.7 1.4** 1.4 1.2 1.6 1.5 1.5 1.45 fluconazole (150 mg tab) containing pda media 100 2.4 3.0 2.0 2.0 2.5 2.9 2.6 1.9 4.0 4.0 2.77 500 1.8 2.2 2.0 2.3 2.0* 2.0 1.8 1.8 2.6 2.6* ** 2.12 1000 1.6 2.6 2.0 2.1 2.0** * 2.4 1.9 1.5 2.0 2.4 2.05 control pda without triazole compound 0.0 7.00 note. *=change in cultural characteristic; **=fruiting structure of mucor absent; ***=reverse side of culture is pink-red as fungal growth absorbs triazole compound to give pink-red color. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 39 published by scholink inc. figure 8. growth of mucor isolates on triazole antifungal drug containing growth media (front side of plate (a) and reverse side of plate (b)) a b www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 40 published by scholink inc. table 4. influence of triazole compounds on growth rate (cm/d) of mucor sp. prevalent in the city air triazole compound concentration (ug /ml) average mucor growth * (in cm on 5 th day) inhibition of mucor growth (% inhibition) inhibition of growth rate (cm /d) itraconazole (200 mg capsule) 100 500 1000 1.77 1.66 1.45 5.23 (74.71) 5.34 (76.28) 5.55 (79.28) 1.04 1.06 1.11 fluconazole (150 mg tablet) 100 500 1000 2.77 2.12 2.05 4.23 (60.42) 4.88 (69.71) 4.95 (70.71) 0.84 0.97 0.99 control (no triazole compound) 0 7.00 cm growth on 5 th day (growth rate 1.4 cm/d) note. *=average growth of 10 isolates of mucor collected at different locations of the city, on particular triazole concentration. 4. discussion the fungus mucor is a causative agent of mucormycosis and mostly affects immunocompromised people. several disease conditions like aids, cancer, diabetes, malnutrition, certain genetic disorders, organ transplants, congenital immunodeficiency, primary immunodeficiency diseases (pdis), lymphohematogenous malignancy (lhm), non-cytotoxic immunosuppression, splenectomy and chronic diseases with limited immune deficits are known as immunocompromised (meidani et al., 2014) and may favor the infection of mucormycosis. the population of immunocompromised persons is estimated to be about 160 million people in the world (anonymous, 2022) and thus this quantum of the population is in the risk group of mucormycosis, if the sufficient cfu of mucor is present in a tidal volume to cause mucormycosis. the presence of up to 90 cfu of mucor/tidal volume seemed to be insufficient to cause mucormycosis, since no case of mucormycosis was reported in the city during the month of may 2022 and in subsequent months as compared to the mucormycosis cases in the same month in 2021. the probable www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 41 published by scholink inc. reason seems to be the hindrance of entry of mucor spores by the cilia in the nostrils into the nasal cavities and paranasal sinuses and the innate immunity of the person. mucormycosis is mainly a disease of the immunocompromised person (pandilwar et al., 2020). thus, the study of microbial air quality index (aqi) is an important issue while studying the air quality of cities and metros. the microbial air quality index can be defined as the sum of various cfu of microbes present in the air and their significance in causing the concern disease/diseases. this is the first publication on microbial aqi, mucor/tidal volume, and the methodology of its enumeration. it is advised to maintain the air quality index for mucor sp, a dominant fungal species in the city air at a minimal level to avoid mucormycosis infection. this can be achieved by employing the air vacuum cleaner machinery, in the mucor species-dominated areas of the city based on the microbial air quality index for mucorales. acknowledgment the authors thank mr. suyog koli, suyash nagre, om diwakar, miss. sweta gadekar, mansi adsare, and sayli diwakar, all graduating students of biotechnology, at city college, nashik, for collection of microbial air samples at different locations in nashik city. references anonymous. (2022). immunocompromised population and the risk of viral variants. in astrazeneca data on file 2021. ref-129335. retrieved from http://www.astrazeneca.com asghar, s. a., majid, z., & mir, s. (2019). rhino-oculo cerebral mucormycosis resistant to amphotericin b in a young patient with diabetic ketoacidosis. cureus, 11(3), e4295. https://doi.org/10.7759/cureus.4295 borkar, s. g. (2017). laboratory technique in plant bacteriology (p. 320). crc press, taylor & francis group, usa. https://doi.org/10.1201/9781315206882 borkar, s. g. (2021). mucormycosis: a surge in mucorales fungal infection in post-covid patients in indian states and insight into known and unknown factors. international journal of global health, 1(3), 26-60. borkar, s. g., borkar, s., ajayasree, t. s., saini, u., & saini, r. (2020). aspergillosis of onion, a concern for human health. british journal of medical and health sciences, 2(11), 638-647. bouza, e., & munoz, p. (2006). mucormycosis: an emerging disease. guinea j. clin microbiol infect, 12, 7-23. https://doi.org/10.1111/j.1469-0691.2006.01604.x choudhary, n. k., & gahlot, n. (2021). mucormycosis: a deadly black fungus infection among covid-19 patients in india. clinical epidemiology and global health, 12, 100900. https://doi.org/10.1016/j.cegh.2021.100900 dannaoui, e. (2017). antifungal resistance in mucorales. international j. antimicrob agents, 50, 617-621. https://doi.org/10.1016/j.ijantimicag.2017.08.010 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 42 published by scholink inc. ellis, d. (2002). amphotericin b: spectrum and resistance. antimicrob chemother, 49, 7-10. https://doi.org/10.1093/jac/49.suppl_1.7 funder, s. (1968). practical mycology: manual for identification of fungi (3rd ed., p. 146). hafner publisher, new york. hallett, s., toro, f., & ashurst, j. v. (2022). physiology, tidal volume. statpearls publishing llc. jane, p., tucci, v. c., vincet, a. l., sandin, r. l., & greene, j. n. (2008). mucormycosis in immunochallenged patients. j. emergencies trauma shock, 1(2), 106-113. https://doi.org/10.4103/0974-2700.42203 meidani, m., naeini, a. l., rostami, m., sherkat, r., & tayeri, k. (2014). immunocompromised patients: review of the most common infections happened in 446 hospitalized patients. j. res med sci, 19(1), s71-s73. monica, p., & chandraprabha, m. n. (2022). risk of mucormycosis in current covid-19 pandemic: a clinical challenge in both inmmunocompromised and immunocompetent patients. molecular biology report, 49, 4977-4988. https://doi.org/10.1007/s11033-022-07160-3 neil, s., nitin, g., & ilan, s. (2021). mucormycosis: time to address this deadly fungal infection. the lancet microbe, 2(6), e343-e344. https://doi.org/10.1016/s2666-5247(21)00148-8 pandilwar, p. k., khan, k., shah, k., sanap, m. a., unnikrishnan, k. s., & nerurkar, s. (2020). mucromycosis: a rare entity with rising clinical presentation in immunocompromised hosts. international journal of surgery case reports, 77, 57-61. https://doi.org/10.1016/j.ijscr.2020.10.075 petrikkos, g., skiada, a., lortholary, o., roilides, e., walsh, t. j., & kontoyiannis, d. p. (2012). epidemiology and clinical manifestation of mucormycosis. clinical infectious diseases, 54(1), s23-s34. https://doi.org/10.1093/cid/cir866 microsoft word ees-v1n1-p33.doc energy and earth science vol. 1, no. 1, 2018 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 33 original paper systems design for energy demand by optimal utilization of renewable energy in robust aquaponic systems tim chen1,2, asim muḥammad3, bertrand chapron4, c.y.j. chen5,6 & alexander babanin7 1 school of geography, earth and environmental sciences, university of birmingham, birmingham, uk 2 department of surface water and maritime systems, fraunhofer i0sb-ast, ilmenau, germany 3 faculty of engineering, king abdulaziz university, jeddah, saudi arabia 4 laboratoire d'océanographie physique et spatiale, centre de brest, ifremer, plouzané, france 5 industrial technology research institute, hsinchu, taiwan 6 brac univ, department of computer science and engineering, dhaka, bangladesh 7 department of infrastructure engineering, university of melbourne, melbourne, victoria, australia received: october 12, 2018 accepted: november 8, 2018 online published: november 21, 2018 doi:10.22158/ees.v1n1p33 url: http://dx.doi.org/10.22158/ees.v1n1p33 abstract in a debate with other reservoirs, ocean waves furnish an ample supply of clean, reliable, and decent energy, but this origin requires to be made a cost-effective fount for physical energy return. for this mission, the proposed membership functions are adopted and stabilization criterion of the closed-loop t-s fuzzy systems are obtained through a new parametrized lmi (linear matrix) inequality which is rearranged by machine learning membership functions. keywords ocean waves, lmi, membership functions 1. introduction wave energy can generate large amounts of clean, safe, reliable, and economical renewable energy, thus making it an attractive source to meet the rapidly growing demand for energy (gericke, 1940). although in its infancy, the wave energy industry is expected, similar to the offshore wind power industry, to become established in several nordic countries because of the rapid growth in the past decade. among the various renewable energy sources (such as solar, wind, and tidal power), wave energy has the highest power density and provides relatively continuous and reliable output, which is advantageous for the operation of the power grids (klinger & naylor, 2012). some large devices are www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 34 published by scholink inc. designed as shown in fig. 1, which indicate the diversity of the practical applications in the ocean. the cost of tapping the wave energy has increased from the 1980s but gradually declined and is likely to further reduce with advances in the technology industry (osmundsen, almklov, & tveterås, 2017). as energy costs from fossil fuels are exorbitant, wave energy could become economically feasible in the near future. thus, policy-makers, the private sector, and the general public are interested in the conversion of wave energy into electrical energy. the two important steps in this process are (1) assessment of the ability of a site to produce electricity and (2) identification of surrounding ecosystems and the potential impacts and activities in support of electricity production (read & fernandes, 2003). figure 1. wave power devices while the waves may provide a source of clean and renewable energy, a wave energy conversion project may harm the protection of the marine species and habitats, and create a strategic conflict with the existing marine ecosystems. wave energy conversion facilities and their potential impacts, including fishing, planktonic and benthic habitat; recreation; aesthetic point of view changes; hydrodynamic and wave environment; and navigational hazards were studied by (bohl, 1977; collins et al., 1975; naegel, 1977). many potential impacts are site specific, and the extent of these impacts on coastal and marine ecosystems is unclear, because the studies on the wave energy conversion projects are limited; hence, the concept is poorly understood. this knowledge gap hindered the development of practical equations to support wave energy projects related to marine spatial planning. an assessment of wave energy capacity of a site considers various factors such as wave energy resources, the characteristics of wave energy conversion device, the cost-effectiveness of energy conversion facility, locational constraints, and uses of the information on ecosystem properties or compatibility with others. marine spatial planning is at a nascent stage in north america, and involves an interaction between the planners to consider the cumulative impact of the procedure on the coastal and marine space human activities (sneed, allen, & ellis, 1975). implementing the wave energy projects and efficient marine www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 35 published by scholink inc. spatial planning requires a comprehensive framework that considers these various kinds of information. it is estimated that the wave power resources can help to identify potential sites of energy-rich areas and sustainable resources. previous studies employed different scales to estimate the potential of wave power. for example, the globaland regional-scale studies have shown that the west coast of europe (i.e., ireland, portugal, and scotland), similar to the north american west coast (i.e., british columbia, washington, oregon, and california), is the main area of wave energy projects because of its potential for abundant wave energy harvest, which can be used to meet the demands of high coastal population areas (lewis, yopp, & schramm, 1978; sutton & lewis, 1982; timmons & ebeling, 2010). previous research focused on a local scale to quantify near-shore wave energy resources and to identify hot spots in the field of wave energy (mollison & holmgren, 1981; todd, 1980). different types of wave energy conversion device are used to extract energy from the waves, and various technologies are employed to calculate how much energy can be harvested as a function of the local wave condition change. for example, using a attenuator-type device (for example, sea snake, the pelamis wave power, edinburgh, scotland) works more effectively in the irish and scottish region (lewis, yopp, & schramm, 1978), where the wave height typically under high sea conditions aids in the estimation. in contrast, the terminator-type devices (for example, an oscillating water column device from energetech corporation, utah, usa) work more efficiently on the west coast of north america (zweig, 1986), where there is disposal of longer period waves (such as swelling). in reality, a wave energy conversion efficiency of the device depends not only on the location of the potential energy to be harvested, but also on income and decisions related to the construction and operating costs of the facility. the economic value of the harvested wave energy facilitates to identify the specific location of energy conversion facility and to evaluate the potential tradeoff between the cost positioning factors related to the installation location, maintenance, and operation of the facility. while the ability to develop the harvest wave energy method is explored in (lewis, yopp, & schramm, 1978; sutton & lewis, 1982; zweig, 1986; mcmurtry, nelson, & sanders, 1990), harvest wave energy does not provide explicit spatial information to assess the cost of wave site energy generation or the other associated estimates. this study developed a wave energy conversion device to identify a potential site, which provides decision support equations for the policy-makers to respond to the challenges of wave energy projects related to integrated coastal and marine spatial planning. first, the study developed a model of wave energy as ecosystem services, and the tradeoffs (investment) equation (mcmurtry, 1992) is a part of an integrated assessment (rakocy 1984; watten & busch, 1984). the wave energy model by using ecosystem services is based on the framework of talese and other researchers (rakocy, 2012) and consists of three parts: (1) the model was based on wave conditions (“supply measures”), (2) the model used a wave energy conversion device to quantify the potential of wave power evaluation (“service standards”) consisting certain technical information in harvesting energy, and (3) the utility of the model was evaluated as capital investment (“value index”) to assess the economic value of wave www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 36 published by scholink inc. energy conversion facilities. second, the study conducted a compatibility analysis to determine the optimum compatibility between the wave energy conversion device and the existing uses of the oceans. investment in an ecosystem service model, including wave energy in the model, is described here. this equation is used in many other coastal and marine spatial planning processes, and can be used for a variety of related marine renewable energy projects to support marine spatial planning (rakocy, masser, & losordo, 2006). 2. evaluation of the formulas the mathematical models of many physical and engineering systems are frequently of high dimension, or possessing interacting dynamic phenomena. the information processing and requirements to experiment with these models for control purposes are usually excessive. it is therefore natural to seek techniques that can reduce the computational effort. the methodologies of large-scale systems provide such techniques through the manipulation of system structure in some way. thus, there has been considerable interest in the research area of modeling, analysis, optimization and control of large-scale systems (mahmoud, hassan, & darwish, 1985). recently, many approaches have been used to investigate the stability and stabilization of large-scale systems, as proposed in the literature (routledge, 2015; deutsch, csordas, sun, & jarnuczak, 2017). during the past several years, fuzzy-rule-based modeling has become an active research field because of its unique merits in solving complex nonlinear system identification and control problems. this approach can obtain more flexibility and more effective capability of handling and processing uncertainties in complicated and ill-defined systems. unlike conventional modeling, fuzzy rule-based modeling is essentially a multimodel approach in which individual rules are combined to describe the global behavior of the system (mei, grossberg, ng, navarro, & ellmore, 2017). in this paper, we consider a fuzzy large-scale system composed of j subsystems with interconnections and each subsystem is represented by the so-called takagi-sugeno fuzzy model. one critical property of control systems is stability and considerable reports have been issued in the literature on the stability problem of fuzzy dynamic systems. however, a literature survey indicates that the stability problem of fuzzy large-scale systems has not yet been resolved. hence, a stability criterion in terms of lyapunov’s direct method is proposed to guarantee the asymptotic stability of fuzzy large-scale systems. 3. system description and stability analysis consider a fuzzy large-scale system f which consists of j interconnected fuzzy subsystems . , 2, ,1 , jjfj  the jth fuzzy subsystem jf is of the following form: www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 37 published by scholink inc.               (1b) ),()( )1( )()()()1( : 1 1 kxck akkxakhkx f j jn n nnjj r i jjijijj j j   where ija is a constant matrix with appropriate dimensions, )(kx j is the state vector, c nj is the interconnection between the nth and jth subsystems, jr is the number of fuzzy implications and )(khij is the normalized weight. each isolated subsystem (i.e., 0njc ) of f is represented by a takagi-sugeno fuzzy model composed of a set of fuzzy implications and the final output of this fuzzy model is described as (laurens, batlolona, batlolona, & leasa, 2018) )1( kx j    jr i jijij kxakh 1 )()( . (2) lemma 1 (bohl, 1977): the jth isolated subsystem (2) is asymptotically stable if there exists a common positive definite matrix jp such that 0 jijj t ijij papaq for jri ,2, ,1  . (3) based on lemma 1, a stability criterion is derived below to guarantee the asymptotic stability of the fuzzy large-scale system f. theorem 1: the fuzzy large-scale system f is asymptotically stable, if each isolated subsystem of f is asymptotically stable and the following inequality is fulfilled (warsito & herman, 2018; wardono, mariani, & candra, 2016; yuanita & zakaria, 2016; mulbar & zaki, 2018; meika, suryadi, & darhim, 2018): )]()()[()()()( 1 2 fjmijmfj r fi ijijm r i ij qqkhkhqkh jj    inj r i in j jn n r i ijnij mkhmkh jj )()([ 11 1        ])()1( 2 jnnm cpj  < 0 for jjrfi j , 2, , 1 , 1  , (4) where f is a positive integral, )( ijm q is the maximal eigenvalue of ijq defined in eq. (3) and ijj t njnjj t ijijn apccpam  , inn t jnjnn t ininj apccpam  . proof: let the lyapunov function for the fuzzy large-scale system f be defined as www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 38 published by scholink inc. )()()()( 11 kxpkxkvkv jj j j j j j j    (5) where jp is the solution of eq. (3). taking the backward difference of v(k), we have )()1()( kvkvkv  = [ { 1   j j )]()()([)]()()( 11 kkxakhpkkxakh j r f jfjfjj t j r i jijij jj     )}()( kxpkx jj t j =      j j r fi jjijj t ij t jij j kxpapakxkh 1 1 2 )())(()(      j j jj r fi fjj t ij t jfjij kxpapakxkhkh j 1 )())(()()( + )()()( 1 1 kpakxkh jj t ij t j j j r i ij j    + )()()( 1 1 kxapkkh jfjj t j j j r f fj j    + )()( 1 kpk jj t j j j   = 54321 mmmmm  , where (6) 1m      j j r fi jjijj t ij t jij j kxpapakxkh 1 1 2 )())(()(     j j r i j t jijmij j kxkxqkh 1 1 2 )()()( )(  , (7)  2m      j j r fi jjfjj t ij t jfjij j kxpapakxkhkh 1 )())(()()( =     j j r fi jjijj t fjfjj t ij t jfjij j kxpapaapakxkhkh 1 )()2)(()()( =     j j r fi fjijj t fjij t jfjij j aapaakxkhkh 1 )]()[(){()()( )(]}2[ kxpapaapa jjfjj t fjijj t ij      j j r fi j t jfjmijmfjij j kxkxqqkhkh 1 )()()]()()[()(  , (8) 3m )()()( 1 1 kxcpakxkh nnjj t ij t j j j r i j jn ij j     )()()( 1 1 kxcpakxkh nnjj t ij j j r i j j jn ij j      , (9) www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 39 published by scholink inc. 4m )()()( 1 1 kxapckxkh jijj t nj t n j j r i j jn ij j     )()()( 1 1 kxapckxkh jijj t njn j j r i j jn ij j       , (10) 5m )()( 1 kpk jj t j j j    ]})()([])()({[ 2211221 1 1    kxckxcpkxckxc jjj t j j j j ])()()1()()()1([ 2 22 2 11 1   kxcpjkxcpj jjmjjm j j      j j j jn nnjjm kxcpj 1 2 ])()()1[(      j j j jn jjnnm kxcpj 1 2 ])()()1[(       j j j jn jjnnm kxcpj 1 22 )()()1(  . (11) from eqs. (9-10), we have  43 mm )( ] [ )()( 1 1 kxapccpakxkh nijj t njnjj t ijj j j r i j jn ij j     ] )( )( [ )( 22 1 1 kxkxmkh njijn j j r i j jn ij j      2 1 1 )( )( kxmkh jijn j j r i j jn ij j      2 1 1 )( )( kxmkh jinj j j r i j jn in j      . (12) substituting eqs. (7-12) into eq. (6) yields  )( kv )]()()[()()( )(){( 1 1 m 2 fjmijmfj r fi ij j j r i ijij t j qqkhkhqkhkx jj      ).(]})()1( )()([ 2 1 1 kxcpjmkhmkh jjnnm j jn r i r i injinijnij j j       4. conclusions and suggestions this paper introduced a practical simulation model for renewable energy in aquaponic systems. the output current has harmonic component of both high order frequencies and dispersed harmonics. the characteristic is more close to the real electric arc furnace property. a flicker testing model is established to test the instantaneous flicker visual sensitivity s. modulating waves of different frequencies and the same amplitude is introduced to test the correctness of the model. it can help to establish a more practical model to simulate a wide output range of harmonics. it would be more help full for harmonic-preventing sets such as active power filter to test their characteristics. the power system would be more reliable and electro-insulating material will have a longer using life. the method is proved to be reasonable and realizable to reflect the real electric arc furnace property. developing future politics requires simple goals, which are beyond economic development and employment or the protection and environmental protection. the difficulty of the maritime market www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 40 published by scholink inc. shows there are many opportunities to increase the pace of sustainable aquatic life and new perspectives that can be used through political support. funding acknowledgement this research was in part enlightened by the grant 106efa0101550 of ministry of science and technology, taiwan. references bohl, m. (1977). some initial aquaculture experiments in recirculating water systems. aquaculture, 11, 323-328. collins, m. et al. (1975). nitrification in an aquatic recirculating system. journal of the fisheries research board of canada, 32, 2025-2031. deutsch, e. w., csordas, a., sun, z., & jarnuczak, a. (2017). the proteomexchange consortium in 2017: supporting the cultural change in proteomics public data deposition. nucleic acids res, 45, d1100-d1106. gericke, w. f (1940). the complete guide to soilless gardening. new york: prentice-hall inc. james, p. (2015). routledge, taylor & francis group: earthscan, from routledge, abingdon, oxon. new york, ny: urban sustainability in theory and practice: circles of sustainability. klinger, d. (2012). naylor r. searching for solutions in aquaculture: charting a sustainable course. annu. rev. environ resour, 37, 247-276. laurens, t, batlolona, f. a., batlolona, j. r., & leasa, m. (2018). how does realistic mathematics education (rme) improve students’ mathematics cognitive achievement? eurasia journal of mathematics, science and technology education, 14(2), 569-578. lewis, w. m., yopp, j. h., & schramm, j. h. l. (1978). use of hydroponics to maintain quality of recirculated water in a fish culture system. transactions of the american fisheries society, 107, 92-99. mahmoud, m. s., hassan, m. f., & darwish, m. g. (1985). large-scale control systems. new york: marcel dekker. mcmurtry, m. (1992). integrated aquaculture-olericulture system as influenced by component ratio (p. 78). ph.d. thesis.: north carolina state university. mcmurtry, m. r., nelson, p. v., & sanders, d. c. (1990). sand culture of vegetables using recirculated aquacultural effluents. applied agricultural research, 5, 280-284. mei, n., grossberg, m. d., ng, k., navarro, k. t., & ellmore, t. m. (2017). identifying sleep spindles with multichannel eeg and classification optimization. comput. biol. med., 89, 441-453. meika, suryadi, d., & darhim. (2018). students’ errors in solving combinatorics problems observed from the characteristics of rme modeling. journal of physics: conference series, 948, 1-6. mollison, b., & holmgren, d. (1981). permaculture one: a perennial agricultural system for human www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 41 published by scholink inc. settlements. international tree crop institute usa. mulbar, u., & zaki, a. (2018). design of realistic mathematics education on elementary school students. journal of physics: conference series, 128, 1-8. naegel, l. c. a. (1977). combined production of fish and plants in recirculating water. aquaculture, 10, 17-24. osmundsen, t. c., almklov, p., & tveterås, r. (2017). fish farmers and regulators coping with the wickedness of aquaculture. aquac. econ. manag, 1-21. rakocy, j. e. (1984). a recirculating system for tilapia culture and vegetable hydroponics. in d. tave (ed.), smitherman ro (pp. 103-114). auburn, al. rakocy, j. e. (2012). aquaponics-integrating fish and plant culture (pp. 344-386). oxford, uk: wiley-blackwell. rakocy, j. e., masser, m. p., & losordo, t. m. (2006) recirculating aquaculture tank production systems: aquaponics–integrating fish and plant culture (p. 454). srac publication. read, p., & fernandes, t. (2003). management of environmental impacts of marine aquaculture in europe. aquaculture, 226, 139-163. sneed, k., allen, k., & ellis, j. (1975). fish farming and hydroponics. aquaculture and the fish farmer, 2, 18-20. sutton, r. j., & lewis, w. m. (1982). further observations on a fish production system that incorporates hydroponically grown plants. the progressive fish-culturist, 44, 55-59. timmons, m., & ebeling, j. (2010). recirculating aquaculture. ithica, ny: cayuga aqua ventures. todd, j. (1980). dreaming in my own backyard. the journal of the new alchemists, 6, 108-111. wardono, w. s. b., mariani, s., & candra, d. s. (2016). mathematics literacy on problem based learning with indonesian realistic mathematics education approach assisted e-learning edmodo. journal of physics: conference series, 693, 1-10. warsito, d., & herman, t. (2018). improving students’ mathematical representational ability through rme-based progressive mathematization. journal of physics: conference series, 948, 1-6. watten, b. j., & busch rl (1984) tropical production of tilapia (sarotherodon aurea) and tomatoes (lycopersicon esculentum) in a small-scale recirculating water system. aquaculture, 41, 271-283. yuanita, p., & zakaria, e. (2016). the effect of realistic mathematics education (rme) implementation to mathematics belief, mathematics representative and mathematics problem solving. advanced science letters, 22(8), 1989-1992. zweig, r. d. (1986). an integrated fish culture hydroponic vegetableproduction system. aquaculture magazine, 34-40. microsoft word ees-v1n1-p42.doc energy and earth science vol. 1, no. 1, 2018 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 42 original paper a new tool preliminary assessment on temporal-comorbidity adjusted risk of emergency readmission (t-carer) tim chen1,2,3,4, asim muḥammad4, bertrand chapron5, c. y. j. chen6,7, & alexander babanin8 1 school of geography, earth and environmental sciences, university of birmingham, birmingham, uk 2 department of artificial intelligence, university of maryland, maryland, usa 3 faculty of intelligence technology, ton duc thang university, ho chi minh city, vietnam 4 faculty of engineering, king abdulaziz university, jeddah, saudi arabia 5 laboratoire d'océanographie physique et spatiale, centre de brest, ifremer, plouzané, france 6 industrial technology research institute, hsinchu, taiwan 7 brac univ, department of computer science and engineering, dhaka, bangladesh 8 department of infrastructure engineering, university of melbourne, melbourne, victoria, australia received: november 6, 2018 accepted: december 10, 2018 online published: december 17, 2018 doi:10.22158/ees.v1n1p42 url: http://dx.doi.org/10.22158/ees.v1n1p42 abstract patients’ comorbidities, operations and complications can be associated with reduced long-term survival probability and increased healthcare utilisation. the aim of this research was to produce an adjusted case-mix model of comorbidity risk and develop a user-friendly toolkit to encourage public adaptation and incremental development. it has been shown in healthcare research that demographics, temporal dimensions, length-of-stay and time between admissions, can noticeably improve the statistical measures related to comorbidities. the proposed model incorporates temporal aspects, medical procedures, demographics, and admission details, as well as diagnoses. the research resulted in the development of temporal-comorbidity adjusted risk of emergency readmission (t-carer) model using routinely collected hospital data. keywords multiple criteria decision making, interval-valued belief distribution, evolutionary algorithm, accuracy, efficiency www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 43 published by scholink inc. 1. introduction there is increasing evidence that the quantification of high-risk diagnoses, operations and procedures, and monitoring changes over time, can greatly improve the quality of readmission models with adequate adjustment. there have been two streams of work on risk scoring comorbidities to estimate future resource utilisation, emergency admission and mortality. firstly, one stream of research looks at the odds ratio of major diagnoses groups and therefore is highly reliant on the whole population statistics. these models stem from crudely summing up the derived weights for comorbidities, which are based on the most recent admission of patients with disregard of temporal patterns. a popular example is the charlson comorbidity index (cci) (charlson, pompei, ales, & mackenzie, 1987), which relies on twenty-two comorbidity groups. one of the recent translation of the cci is the national health service (nhs) england version of the cci (nhs-cci), that is continuously being updated (aylin, bottle, jen, middleton, & intelligence, 2010; bottle, jarman, & aylin, 2011; hscic, 2014; 2015; 2016). the second stream of models uses a diagnosis classification approach based on simi larities, type, likelihood or duration of care. however, they are usually very complex and specialised to highly particular settings and populations. also, these models use a period of care records in past, but temporal patterns are greatly ignored. one prominent method is the elixhauser comorbidity index (eci) (elixhauser, steiner, harris, & coffey, 1998; ahrq, 2016), which relies on thirty comorbidity groups and 1-year lookback period. unlike the cci, the eci is using diagnosis-related groups (drg), which was first developed by fetter et al. (fetter, shin, freeman, averill, & thompson, 1980) and is based on icd (international statistical classification of diseases) diagnoses, procedures, age, sex, discharge status, complications and comorbidities. a recent adaptation of the eci is the ahrq-eci, which is actively being maintained by the us public health service (ahrq, 2016). another well-established method is the john hopkin’s (weiner & abrams, 2011) adjusted clinical groups (acgs), which is a commercial tool. the model uses a minimum of 6-month and maximum of 1-year prior care records, and it encapsulates 32 diagnoses groups, known as aggregated diagnosis groups (adgs), and their aggregations called expanded diagnosis clusters (edcs). moreover, these indices are initially developed to adjust for particular risks, like mortality risk and care utilisation, but they are commonly used in a variety of risk adjustment problems in critical care health services research. in the machine learning pipeline that was developed in the prior stage of our research (mesgarpour, chaussalet, & chahed, 2017), comorbidity index was an extremely significant factor and has a high potential for further improvement. presently, comorbidity risk indices have four major weakness areas: robustness, temporal adjustment, population stratification, and the inclusion of associated factors to comorbidities and complications. in this research, we are going to improve on these four major areas. firstly, to make the risk score relevant to different environments, an approach must be used to model complex correlation between variables and states. secondly, to better distinguish the shortand long-term conditions (i.e. prior www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 44 published by scholink inc. admission, length-of-stay, and delta-time between admissions), the temporal dimension may be included in form of life-table or a polynomial weight function. thirdly, population stratification is a major factor in the prevalence of medical conditions, and therefore must be adjusted. fourthly, major correlated factors to diagnoses may be included directly or indirectly (latent) to improve the risk estimates, including secondary diagnoses, operations, procedures and complications. the first main outcome of this research was the development of the temporal comorbidity adjusted risk of emergency readmission (t-carer), to address the four mentioned issues. the secondary outcome was to release a generic, open source and easy-to-use environment to model the comorbidity risk. it consists of a user-friendly ipython notebook, which calls procedures in mysql and python, in addition to third-party libraries. the t-carer toolkit and documentation are available online (apache 2016). furthermore, comorbidity risk models are constrained by the population and sam ple characteristics, data quality (e.g. missing diagnoses or delayed death registration) and modelling approach. there is a wide range of literature that focuses on modification and benchmarking comorbidity indices, using different datasets, cohorts, complexity, length-of-stay and claims. the prediction targets vary, it includes in-hospital and 1-year mortality, and in some cases 7-day and 30-day readmission (austin, stanbrook, anderson, newman, & gershon, 2012; holman, preen, baynham, finn, & semmens, 2005; gagne, glynn, avorn, levin, & schneeweiss, 2011; mehta, dimou, adhikari, tamirisa, sieloff, williams, kuo, & riall, 2016; sharabiani, aylin, & bottle, 2012; januel luthi, quan, borst, taff’e, ghali & burnand, 2011). moreover, there have been many attempts at scoring sur gical outcome and complications that are affected by comorbidity (mehta, dimou, adhikari, tamirisa, sieloff, williams, kuo, & riall, 2016; armitage & meulen, 2010; dfi, 2013). however, they are mainly based on non-administrative clinical variables or are specialized to very specific outcomes and populations. 2. methodology 2.1 data in this study, a bespoke extract of the hes inpatient data was used, which contains records from april 1995 to april 2010. two main samples were randomly selected from this database, which includes 20% of total unique patients from 1999-2004 and 2004-2009 periods. then, each main sample was divided into two equal half, to be used for training and testing. each time-frame was divided into one year of trigger-event, one year of prediction period, and three years of prior-history. the population includes all alive patients greater than one-year-old that have an admission within the trigger year. the prediction target variables are 30and 365-day hospital emergency admission to the inpatient. 2.2 features after the data extraction step, several stages of data pre-processing and feature selection were carried out using the framework introduced by mesgarpour et al. (2016). firstly, a set of data pre-processing www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 45 published by scholink inc. steps are applied, then the feature selection steps are carried out. also, before carrying out the feature selection steps, features are aggregated and split into temporal events, to capture the events through time. 2.2.1 pre-processing the pre-processing stage implements data selection, removals of invalids and imputations of observations. also, the feature re-categorisation was applied in this stage, to reduce sparsity and to better capture non-linear relationships. in re-categorisation step, a clinical grouper, known as the clinical classifications software (ccs), was used to categorise the diagnoses, to better capture comorbidities’ patterns and cross-correlations. the ccs categorises the icd-10 (10th revision of the icd) diagnoses and operations into a number of categories that are clinically meaningful (hscic, 2014; elixhauser & steiner, 2006; ahrq, 2016). furthermore, operations and procedures were categorised using the major categories of the opcs-4, but alternative coding categorisation may be used, like icd-10-pcs. the opcs-4 is an alphanumeric nomenclature (similar to icd-10-pcs), and is used by the nhs england and has an implicit categorisation for operations based on clinical categories rather than cost or risks. 2.2.2 life-table and aggregation healthcare administrative data are severely unbalanced regarding the amount of longitudinal (panel) data per patient and their distributions over the years. statistical methods are not equipped to handle these type of unbalances directly. therefore, the survival analysis’s life-table approach was used to keep track of temporal events (singer & willett, 2003). based on previous studies and the initial statistical analyses, four levels of temporal features were generated: 0-30, 30-90, 90-365 and 365-730 days. these four levels capture part of the temporal aspect of comorbidities, in addition to the delta-time between admissions (gapdays) and the length-of-stay (epidur) features that include temporal metadata. furthermore, in the modelling stage, we applied several techniques to capture the complex temporal patterns of patients’ comorbidities. the temporal features were summarized in each temporal level based on several aggregation functions, including prevalence, count and average. this stage increased the number of features by more than fifty folds. 2.2.3 feature selection after feature generation, a feature pool was produced based on the developed features. thereafter, the feature selection step has been carried out. firstly, the features were filtered out based on their linear cross-correlation, as well as frequency and sparseness (percentage of distinct, and the ratio of the most common value to the second most common). thereafter, the continuous features have been transformed using two feature transformations methods: scale-to-mean and yeo-johnson (yeo & johnson, 2000; breiman, 2001; hawkins & blakeslee, 2007). both methods can be used to transform the data, to improve normality. although, feature transformations would not guarantee better convergence or very stable variance for any dataset, they have been applied to avoid inputting skewed features into models. moreover, a downside of www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 46 published by scholink inc. transformations is that they make model interpretation harder, and can negatively impact the relationship between correlated features in the model. therefore, the highly correlated features were removed after transformations. 2.3 modelling approaches the aim of this research is to model emergency readmission using a minimal number of generic features that can be used for short and long-term predictions with high correlation to the comorbidity risk. in this study, there is no condition on the trigger event admission and a minimal number of features are used. this makes it different from general readmission models, like the ermer (mesgarpour, chaussalet, & chahed, 2017), that use a wide range of features and may enforce the emergency admission condition for both trigger-event and future-event. 2.3.1 logistic regression the first algorithm is a logistic regression with l1 regularisation (1.0), using liblinear optimisation algorithm (fan, chang, hsieh, wang, & lin, 2008) with the maximum of hundred iterations and a warm-up period. the random forest method is an ensemble decision tree, which was first introduced by breiman et al. (2001). it is based on the cart algorithm (breiman, friedman, stone, & olshen, 1984) and the bagging ensemble method (breiman, 1996). however, the breiman random forest is sensitive to highly correlated features, and the scale or categories of features (strobl, boulesteix, zeileis, & hothorn, 2007; tolosi & lengauer, 2011). 2.3.2 random forest we used a random forest method using the breiman algorithm (breiman, 2001), with gradient boosted regression trees, gini index criterion and 1000 trees in the forest. 3. deep neural network and results we implemented a deep neural network (dnn) based on the wide and deep neural network (wdnn) algorithm, which was introduced by cheng et al. (2016). dnns are a class of artificial neural networks (ann) with multiple hidden layers, which allow modelling more complex non-linear problems (bengio et al., 2009; schmidhuber, 2015). dnn act like ann, but with better ability to model complex non-linear models with a more effective representation of features in each layer. the wdnn is a dnn which combines benefits of memorization and generalization. the wdnn consists of two parts: the wide model and the deep model. the wide part of the model consists of a wide linear model for highly sparse features (random features that are rarely active) and is good at memorizing specific cases. the wide part may also include groups of crossed features. inside of a group of crossed features, each level of one feature occurs in combination with each level of other features. the glm (eq. 1) and the cross-product transformation (eq. 2) for the wide part are defined as the following: wty x b  (1) www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 47 published by scholink inc.   1 ki d c k i i x x   ;  0,1kic  (2) , where y is the prediction, x is a vector of features of d features, w is model parameters and b is the bias. on the other hand, the deep part of the model composed of hidden layers of feed forward neural network with an embedding layer and several hidden layers for any other variable. the deep part can be particularly good in the generalization of cross-correlations. each hidden layer performs the following operation (eq. 3). ( 1) ( ) ( ) ( )(w )l l l la f a b   (3) , where w(l), a(l) and b(l) represent weights, actuation’s and bias for layer l, respectively. finally, the wdnn for the logistic regression problem (y) can be formulated as the following (eq. 4): ( ), )( 1| ) ( [ ( )] flt t wide deepp y w wx x a bx     (4) where σ(.) is the sigmoid function, φ(x) is the cross-product transformations of x features and w. are the weights. in our study, the wdnn model applies adadelta optimiser (duchi, hazan, & singer, 2011) for the gradients of the deep part, and implements the rectified linear unit (relu) activation function to each layer of the ann (lecun, bengio, & hinton, 2015). in overall, the wdnn and the random forest models provide a better fit for the 30and 365-day emergency readmission problems. for the 365-day, the wdnn produces a marginally better receiver-operating characteristic (roc) compared to the random forest, and significantly better roc compared to the logistic regression (figure 1). also, the wdnn models have very strong precision (positive predictive value), accuracy, and micro-average f1-score. on the other hand, the random forest models have very high sensitivity (true positive rate) and f1-score. because the classes are highly unbalanced, the precision-recall curve (figure 2) was used, to compare the area under the curve, average precision and average recall. the plot demonstrates that the area under the curves are significantly lower for 30-day models compared to 365-day models. also, sample-2 models have a bigger area under the curve across the models. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 48 published by scholink inc. figure 1. the abstract graph of the wide and deep neural network (wdnn) (a) receiver operating characteristic (roc). (b) precision-recall curve. figure 2. performance comparison 4. discussion and conclusions we compared the performance of the t-carer against commonly used comorbidity index models using different samples and population cohorts across a ten year period. our analyses of the t-carer and the nhs-cci for different diagnoses categories demonstrated that our model performed best in the majority of comorbidity groups, and in overall t-carer models show better results against previous www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 49 published by scholink inc. surveys of ccis and ecis. an advanced research will be sought to identify an approach to score commodities by the inclusion of diverse categories of diagnoses, operations and complexities. the t-carer performs consistently across tests and validations, and it outperformed against charl-son and elixhauser indices which are widely used for prediction of comorbidity risks. funding acknowledgement this research was in part enlightened by the grant 106efa0101550 of ministry of science and technology, taiwan. references ahrq. 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(2011). improved accuracy of co-morbidity coding over time after the introduction of icd-10 administrative data. bmc health services research, 11(1), 194. https://doi.org/10.1186/1472-6963-11-194 lecun, y., bengio, y., & hinton, g. (2015). deep learning. nature, 521, 436-444. https://doi.org/10.1038/nature14539 mehta, h. b., dimou, f., adhikari, d., tamirisa, n. p., sieloff, e., williams, t. p., … riall, t. s. (2016). comparison of comorbidity scores in predicting sur gical outcomes. medical care, 54(2), 180-187. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 51 published by scholink inc. https://doi.org/10.1097/mlr.0000000000000465 mesgarpour, m., chaussalet, t., & chahed, s. 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(2000). a new family of power transformations to improve normality or symmetry. biometrika, 954-959. https://doi.org/10.1093/biomet/87.4.954 energy and earth science vol. 5, no. 3, 2022 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 original paper my research collaborations with german scientists and scientific institutions over the past six decades robert cooper liebermann 1 1 mineral physics institute and department of geosciences, stony brook university, stony brook, ny, usa received: july 13, 2022 accepted: july 26, 2022 online published: september 7, 2022 doi:10.22158/ees.v5n3p1 url: http://dx.doi.org/10.22158/ees.v5n3p1 abstract over the past six decades, i have maintained research connections with german scientists and scientific institutions while pursuing an academic career focusing on scientific discoveries of the physical properties of minerals at high pressures and temperatures. during this period, i have also visited many research laboratories in germany, including bayreuth, berlin, frankfürt, giessen, hamburg, karlsruhe, kiel, mainz, marbach, munich, potsdam, and stuttgart. the objective of this paper is to relate this history. keywords mineral physics, german scientists, research collaborations 1. introduction over the past decade, i have concentrated on writing papers on my history pursuing a scientific career in mineral physics. recently, i have published papers on my research collaborations with french, czech, chinese, russian and english scientists in the international journal of geosciences (liebermann, 2021 a,b,c; 2022 a,b). this new paper is of a similar genre, with the notable difference that it documents my collaborations with both german scientists and scientific institutions in germany. as will become clear in what follows, not all my connections with german scientists have occurred in germany and not all scientists with whom i have collaborated in scientific institutions in germany were germans. finally, i document my german heritage. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 2 published by scholink inc. 2. the lamont years in the 1960s during my graduate studies at the lamont geological observatory of columbia university (see liebermann, 2019a), i met many prominent geophysicists from other countries, who had been invited by jack oliver, head of the seismology department. among these was hans berckhemer, who had extensive interactions with oliver, maurice ewing and frank press, as well as we graduate students. i later visited berckhemer in frankfurt am main in germany (see below). figure 1. hans berckhemer several other graduate students were from germany. my first office mate was goetz büchbinder, who was born in germany and obtained his m.s. degree in nova scotia. klaus jacob was a student in geomagnetism whom i later visited in melbourne, australia. another german student in seismology was jörge ansorge. in 1967, i attended the iugg congress in zürich and presented a paper with paul pomeroy on the “relative excitation of surface waves by earthquakes and underground explosions”. after the congress, i visited ansorge in karlsruhe with art mcgarr. that was my first visit to germany and included rottweill and reutlingen while exploring my german heritage (see details below). ansorge later moved to eth in zürich to join research group of stephan mueller. hartmut spetzler (see figures 2 and 3 below) was my contemporary in graduate school, hartmut at caltech and me at columbia. we met for the first time when he visited orson anderson’s mineral physics lab at lamont to consult with orson and edward schreiber. hartmut had been tasked with establishing an ultrasonics laboratory at caltech by don anderson. over the subsequent years, we have maintained close connections, most recently in 2016 when we both attended a meeting of the european high-pressure research group in bayreuth. when hartmut was on sabbatical at the university of mainz, i drove with him and his wife ria to visit hartmut kern in kiel. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 3 published by scholink inc. 3. the anu years in the 1970s from 1970 to 1976, i was on the research faculty of the research school of earth sciences of the australian national university (anu) in canberra and worked in the laboratory of ted ringwood (see liebermann, 2020). there i met gerhard brey who was a student of david green. back in germany, gerhard had a short stint at the university of hannover, before moving as a research scientist to the max-planck-institute for chemistry in mainz (1978-1994). there, he built his experimental petrology laboratory, in the cosmochemistry division headed by heinrich wänke. in 1994, gerhard took the position as chair of geochemistry and petrology at the johann wolfgang goethe university in frankfurt am main, germany. somewhat later i visited him in frankfurt with berckhemer in my role as president of compres (consortium for materials properties research in earth sciences). at the 1973 meeting of the international association of seismology and physics of the earth’s interior [iaspei] in lima, peru, charles drake encouraged me to organize a workshop in eastern europe, so that young scientists from countries in eastern europe could attend. vládislav babuška, jaroslava plomerová, vlastislav červený and i had convened the first of these workshops in 1976 at the castle of liblice in central bohemia on “anisotropy and heterogeneity of the lithosphere” (babuška and liebermann, 1977). there were many german scientists at the liblice workshop, including heiner vollstädt and heinz stiller from the central institute of for physics of the earth (zipe), which was an institute of the academy of sciences of the gdr (german democratic republic) in potsdam. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 4 published by scholink inc. figure 2. the workshop in liblice was attended by 75 scientists from 12 countries. german ids: heiner vollstädt—third to right of manghnani; heinz stiller-behind vollstädt; karl fuchs; hartmut spetzler figure 3. rick o’connell, enzo boschi, francesco mulargia, brian o’connell, hartmut spetzler at liblice in 1976 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 5 published by scholink inc. 4. the stony brook years from 1976 to present in 1976, i moved from the anu to stony brook university to join the faculty of the department of geosciences (see liebermann, 2019b). over the ensuing years, i have had extensive research collaborations with staff of german scientific institutions. in1981, i was invited by fritz rummel and werner schreyer to participate in an international meeting in bad honnef and presented a paper on the elasticity of minerals at high-pressure and temperature (liebermann, 1982). the work presented in this paper was an outgrowth of research performed at the anu in canberra and with barbara leitner and peter lellis at stony brook. before the meeting, i visited the laboratory of hans berckhemer in frankfurt and hartmut kern in kiel. today, there are two prominent institutes of geosciences in germany: the bayerisches geoinstitut (bgi) in bayreuth and the geoforschungszentrum (gfz) in potsdam, both of which i have visited in the past 30 years. in the following sections, i describe my collaborations with these institutes and the scientists who have worked there. 4.1 bayerisches geoinstitut (bgi) in the early 1980s, while chairing a committee for the bavarian science ministry to examine the state of earth sciences in bavarian universities, the physical chemist ulrich franck of the university of karlsruhe suggested that geosciences in germany would benefit from an institute focused on the experimental investigation of the earth. the ministry encouraged a plan to be drawn up that was further developed by the petrologist werner schreyer of the ruhr-university; schreyer’s plan proposed the establishment of the bavarian research institute for experimental geochemistry and geophysics or bayerisches geoinstitut (bgi). i served on the search committee for a director of bgi along with hans berckhemer. on the 1 st april 1986 fritz seifert became the founding director of the new geoinstitut established at the universität bayreuth, which was itself at the time only 11 years old. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 6 published by scholink inc. figure 4. the staff of bgi as of 1987; director seifert is 3 rd from the right; sharon webb is first on the left over the next 5 years, the staff of bgi grew rapidly and attracted many international visitors. figure 5. the staff of bgi in 1992. note. catherine mccammon is first on left in front row; seifert is 3 rd to her left; dave rubie is on his left. sharon webb is 1 st to left of him; don dingwell is just behind and to the left of her; tomo katsura is 3 rd to left of webb in front row. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 7 published by scholink inc. figure 6. international visitors to bgi jean-paul poirier often visited bayreuth to work on transmission electron microscopy investigations with falko langenhorst, who is now a professor of mineralogy at the university of jena. evolution of large-volume, high-pressure apparatus at bgi (frost et al., 2004). eiji ito was a graduate student at osaka university and worked with naoto kawai, the original inventor of uniaxial split-sphere apparatus (ussa). ito later moved to misasa, japan to the institute for the study of the earths’s interior (isei) and installed a 5000-ton version of the ussa. this ussa-5000 apparatus manufactured by sumitomo heavy industries later served as the model for multi-anvil laboratories at stony brook university in the u.s. (liebermann, charles prewitt and donald weidner), at the university of alberta in canada (christopher scarfe), and the bayerisches geoinstitut in germany (dave rubie). when dave rubie moved from the university of manchester in england to bgi in 1998, he visited ito in misasa and our laboratory in stony brook. rubie’s sumitomo 1200-ton press arrived at bgi in september 1989 and was the first ussa multi-anvil apparatus to be installed in europe. a second press, an overhauled industrial version called hymag, was installed at bgi in 1991; this press was originally used in ulrich franck’s lab in karlsruhe in conjunction with a belt-type apparatus. i was able to see both of these presses when i first visited bgi in 1992. the third multi-anvil apparatus at bgi was a 5000-ton press installed in the mid-1990s, also manufactured by sumitomo; its installation was observed by ulrich franck and franz görlich. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 8 published by scholink inc. figure 7. ulrich franck and franz görlich observing the installation of the 5000-ton sumitomo press at the bgi figure 8. dave rubie and colleague unpacking boxes at bgi for the operation of the 5000-ton press after dave moved to bgi in 1998, he collaborated with takehiko yagi to convene the 5 th high pressure mineral physics seminar in verbania, italy in 2002. many german scientists attended that seminar, as well as the subsequent ones in 2007 on matsushima island near sendai, japan, in 2012 on lake tahoe in granlibakken, calfornia and 2017 in st. malo, france (liebermann, 2014). www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 9 published by scholink inc. bgi visitors program throughout its history, bgi has generously invited visitors to work with the staff in bayreuth. one of these visitors has been steve jacobsen (initially from the university of colorado where he was a graduate student of joe smyth and hartmut spetzler). steve spent two years of his graduate career at bgi working with hans-josef (hanni) reichmann to develop techniques to perform ghz ultrasonics experiments in a dac. one of their projects is illustrated below. “every good single-crystal, diamond-anvil experiment must start with a good multi-anvil experiment”. figure 9. 5000-ton press at bgi [courtesy of bgi] www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 10 published by scholink inc. figure 10. single crystals of hydrous wadsleyite synthesized in the 5000-ton press at bgi by steve jacobsen [photo courtesy of steve jacobsen] jacobsen used these large crystals to perform high-temperature acoustic experiments in a new diamond-anvil apparatus he developed in collaboration with reichmann and anastasia kantor from bgi and hartmut spetzler (jacobsen et al., 2005). in this apparatus, shear waves were generated by reflecting p waves into vertically-polarized s waves, thus allowing simultaneous measurement of both compressional and shear wave velocities. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 11 published by scholink inc. figure 11. diamond-anvil apparatus designed to conduct gigahertz ultrasonic experiments at high pressures and temperatures [13] their data on hydrous wadsleyite were published in jacobsen’s 2006 review paper (jacobsen, 2006). www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 12 published by scholink inc. figure 12. steve jacobsen and hartmut spetzler at retirement of joe smyth from university of colorado note. joe smyth has published many crystallographic papers using large single crystals from bgi in collaboration with dan frost, who is now in charge of the large presses. other staff at bgi and my research connections catherine mccammon: i first met catherine when she was a graduate student at the anu in the 1970s and have followed her career with interest and admiration in subsequent years. her research considers mantle processes and geochemistry, as well as the crystal properties of minerals, with an emphasis on the characteristics of iron in high-pressure materials and measuring their oxidation states and spin transitions using mössbauer spectroscopy. tomo katsura: phd from okayama university in misasa and currently a professor at bgi. gerd steinle-neumann: phd at university of michigan with lars stixrude and then postdoc at the geophysical laboratory with ronald cohen. now a professor at bgi, focusing on theoretical mineral physics. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 13 published by scholink inc. leonid dubrovinsky and natalia dubrovinskaia: specialists in x-ray diffraction studies at the european synchrotron (esrf) and laboratory studies using mössbauer spectroscopy. both are professors at the university of bayreuth. tiziana boffa-balaran: her student julien chantel visited stony brook and argonne national laboratory to consult with baosheng li and yanbin wang on high-pressure ultrasonic experiments in conjunction with x-ray radiation. she also collaborated with dubrovinsky and razvan caracas on study of ferroelastic phase transition in aluminosilicate hollandite (boffa-balaran et al., 2009). sharon webb: a phd student of ian jackson at the anu, sharon and her protégé ruth knoche have developed techniques for performing ultrasonic interferometry experiments in multi-anvil presses (knoche et al., 1997). this work closely parallels work in my laboratory at stony brook by baosheng li (li et al., 1996); interestingly, both endeavors can be traced to ian jackson at the anu. sharon is now a professor of physical chemistry and mineralogy at the georg-august-university in göttingen. geoforschungszentrum (gfz) in potsdam the gfz german research centre for geosciences, also known as gfz helmholtz centre potsdam or just gfz, is a national research center for earth sciences in germany located on the telegrafenberg in potsdam, in the german federal state of brandenburg. it is part of the helmholtz association of national research centres. “gfz” stands for geoforschungszentrum (geo-research centre). gfz was established after re-unification of germany on oct 3, 1990. it is the latest in a long line of research institutes that have been located on the telegrafenberg of the academy of sciences of the gdr (german democratic republic, including the institute for the physics of the earth (zipe). the history of the gfz can be traced back to the geodatisches institut potsdam, an institution of the prussian academy of sciences. under the directorship of friedrich robert helmert from 1886 to 1917, the institute developed into the world’s leading center for scientific geodesy. gfz is the successor of zipe, where heiner vollstädt and heinz stiller had been working. under the leadership of heiner vollstädt, zipe decided to construct a split-sphere apparatus with the objective of attaining pressures of 1 mbar; however, the water used as the pressure medium could not generate sufficient pressure to achieve this goal. this apparatus is now on display at the gfz in potsdam. https://en.wikipedia.org/wiki/earth_science https://en.wikipedia.org/wiki/telegrafenberg https://en.wikipedia.org/wiki/potsdam https://en.wikipedia.org/wiki/brandenburg https://en.wikipedia.org/wiki/helmholtz_association_of_german_research_centres https://en.wikipedia.org/wiki/helmholtz_association_of_german_research_centres www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 14 published by scholink inc. figure 13. split-sphere apparatus from the zipe in potsdam in the late 1970s, now at the gfz lobby (courtesy of hans-joachim mueller) my principal interaction with scientists at the gfz has been with hans-joachim mueller, who was initially on the staff of zipe. after the reunification of germany, he began to attend seminars at the free university of berlin, where he first met frank schilling. they commenced a collaboration focused on utilizing large-volume presses installed at the deutsches elektronen-synchrotron (desy), max80 then max200x. in 2006, hans moved with schilling to the karlsruhe institute of technology (kit). in a pioneering effort, a modified dia apparatus was designed by a team led by osamu shimomura and takehiko yagi and installed on an x-ray beamline at the photon factory of the national laboratory for high energy physics (kek) in tsukuba, japan; it was called max-80 for “multi-anvil-type x-ray system designed in 1980”. our stony brook copy of max-80 was installed on beamline x17b2 at the national synchrotron light source of the brookhaven national laboratory and was christened sam85 in honor of osamu fukunaga who helped design it and osamu shimamura who helped install in at stony brook in 1985. a similar max-80 was acquired by eckhard hinze at university of giessen in the late 1980s and in 1991 installed on the double ring store iii ring of the hamburger synchrotron laboratory (hasy-lab) at the deutsches elektronen synchrotron (desy) in germany. later, a larger maa designed to reach pressures of 25 gpa was installed at hasylab and named max200x. see papers by mueller and colleagues for additional details of max80 and max200x experiments (mueller et al., 2006). www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 15 published by scholink inc. figure 14. max-80 in germany note. transferred from the laboratory of eckhard hinze in giessen to the gfz in potsdam for preparation to install at desy in 1991 (courtesy of hans-joachim mueller) figure 15. max80 at hasylab www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 16 published by scholink inc. figure 16. max200x at desy with hans-joachim mueller, max voggenreiter and frank schilling (courtesy of hans-joachim mueller) figure 17. max200x at desy in 2009 with the author and hans-joachim mueller (copyright r. c. liebermann) hans mueller visited our high-pressure laboratory at stony brook on several occasions. first with frank schilling and others when they were preparing to install max200x at desy and subsequently to discuss ultrasonic experiments in our multi-anvil, high-pressure apparatus with baosheng li. during the latter visit, hans and his colleague joern lauterjung conducted a successful experiment on the sound velocities of anorthite with baosheng li. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 17 published by scholink inc. i first visited the gfz in 2003 when i was a visiting professor at the université paul sabatier in toulouse, france, on sabbatical leave from stony brook. later when i was the president of compres, i visited desy and talked with director edgar wecker on the importance of high-pressure mineral physics experiments at synchrotrons. other scientists at gfz with whom i have maintained connections hans-josef (hanni) reichmann: formerly at bgi and now on faculty of gfz; a continuing interest in the elastic properties of minerals, using both ghz interferometry and brillouin spectroscopy. monika koch-müller: research interests in the stability, phase relations, crystal chemistry and crystal physics of earth materials. we have met at several meetings of the ehprg in bayreuth. hauke marquardt—on staff of gfz and also an associate professor at oxford university in britain. collaborator on brillouin scattering experiments with sergio speziale and tom duffy. sergio speziale: led the review paper on brillouin scattering and its applications in geosciences with hauke marquardt and tom duffy (speziale et al., 2014). potsdam is also famous for its castle of sans souci, built by king frederick ii of prussia, who was a good friend of the french philosopher voltaire, with whom he maintained an extensive correspondence. figure 18. sans souci castle in potsdam: home of prussian king frederick ii (aka frederick the great), with whom voltaire corresponded note. voltaire visited sans souci in 1750. i visited with my wife barbara in 2003. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 18 published by scholink inc. figure 19. frederick the great and voltaire at sans souci in 1750 4.2 other german scientists and german institutions hartmut kern at the christian-albrechts-universität in kiel. his laboratory, which i visited in 1981, includes a triaxial press with cubic anvils. reinhard (reini) boehler: graduate student in the laboratory of george kennedy at ucla. formerly director of max planck institut für chemie, mainz, germany and research scientist at the geophysical laboratory of the carnegie institution of washington. now at oak ridge national laboratory after leaving carnegie and efree. when he was being considered for a position at the max-planck-institut für chemie in mainz, i was pleased to offer my strong support for his candidacy. at mainz and more recently at carnegie, reini has pioneered new types of diamond-anvil cells for high-pressure research, most notably a large-volume dac for neutron diffraction studies. karl syassen: at the max-planck-institute fur festkorperforschung in stuttgart. we met most recently at the ehprg in bayreuth in 2016. syassen told me that he was born in rottweil and i later visited him in stuttgart (see below for my family’s connection to rottweil). lars ehm: now associate professor in department of geosciences at stony brook. phd from christian-albrechts university in kiel in department of mineralogy in crystallography group, led by prof. dr. wulf depmeier. co-principal investigator with liebermann and gabriel gwanmesia (delaware state university) on diversity initiative on career path for african-american students from historically black colleges and universities (hbcus) to national laboratories of the u.s. department of energy. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 19 published by scholink inc. figure 20. eos, earth and space sciences news, vol. 97, issue 13, pp. 9-11, 1 july 2016 4.3 germans and german institutions germans in non-german institutions ekhard salje lars ehm hartmut spetzler stefan klotz reinhard boehler helmut schloessin goetz büchbinder non-germans in german institutions dave rubie dan frost www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 20 published by scholink inc. steve jacobsen sharon webb tomoo katsura catherine mccammon leonid dubrovinsky natalia dubrovinskaia sergio speziale my german heritage i am descended from german ancestors on both the side of my paternal grandfather (karl gottlob liebermann) and my paternal grandmother (anna weitershausen liebermann). on the liebermann side, my earliest known ancestor is franz liebermann (1670-1737). he married the widow of the beer brewer in rottweil. this brewery was founded in the 12 th century and the liebermanns owned it for 3 generations before it passed out of the family. the brewery building still exists and i have seen it when i was in rottweil in 1967. it is outside the town wall on the bank of the river below. on side of anna weitershausen, my cousins alfreda liebermann and mary anna macqueen have done extensive research, including a visit to germany in the 1990s. via my paternal great-grandfather, carl weitershausen we are related to lucas cranach the elder (1472-1553), the german renaissance painter who was a close friend of martin luther. we are eventually related to charlemagne (747-814 ad) emperor of the roman empire (800-814) via st. elizabeth of hungary (1207-1231). st. elizabeth of hungary was the wife of ludwig iv of thuringia (1200-1227). i am her descendant thru her great-great-great grandson ludwig i of lower hesse and his mistress, margarethe von hozheim. by way of her husband, i am a descendant of charlemagne. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 21 published by scholink inc. figure 21. my great-grandfather (urgroßvater) was roman constantin liebermann, who was born in rottweil in 1848 and married in reutlingen in 1873 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 22 published by scholink inc. figure 22. one of roman’s wedding gifts was a holy bible (heilige schrift), a martin luther version since 1873, this holy bible has been in the liebermann family, to be inherited by the oldest son, who has a son of the protestant faith. thus, the liebermann family bible has passed from roman to karl gottlob (1930) to harold (1969 to my father) and to me (2000). it now resides in a bookcase in our home in east setauket, new york. 5. dedication to johannes and ingrid voigt of marbach-am-neckar, germany my wife barbara and i first met johannes and ingrid voigt when johannes and i were both on the research faculty of the australian national university in canberra. we both lived in the university flats in the nearby suburb of garran. johannes and i often babysat for our young daughters, carmen and karen at the sandbox near our flats. while the girls played, we discussed the affairs of the world; actually, i mostly listened while johannes lectured. since the 1970s when both of our families moved back to the northern hemisphere, we have often visited the voigts in marbach. our most recent visit was in 2016. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 23 published by scholink inc. figure 23. ingrid and johannes voigt with my wife barbara in marbach-am-neckar in 2016 6. conclusion this paper summarizes my research collaborations with german scientists over the past six decades. i have presented both the scientific achievements and the personal connections which resulted from these collaborations. finally, i document my own german heritage from the family ownership of the beer brewery in the 18 th century to my inheritance of the liebermann family bible. i would like to dedicate this paper to ingrid and johannes voigt, our friends from marbach whom we first met in australia in 1970. acknowledgements i am grateful to tiziana boffa-ballaran, tom duffy, lars ehm, dan frost, steve jacobsen, stefan klotz, alfreda liebermann (my cousin), hans-joachim mueller, jean-paul poirier, dave rubie, hartmut spetzler and sharon webb for their correspondence and contributions to this historical paper. my collaborations with these “german” colleagues have been supported by research grants from the nsf geophysics program and the nsf science and technology center for high pressure research [chipr]. this report was written with support from a research grant to baosheng li and myself from the national science foundation (ear-1524078). www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 24 published by scholink inc. conflicts of interest the author declares no conflicts of interest regarding the publication of this paper. references babuska, v., & liebermann, r. c. (1977). report on international symposium on “physical properties of upper mantle rocks in relation to geodynamic processes” in liblice, czechoslovakia, 17-22 may 1976, eos, trans. amer. geophys. un., 58, 156-159. https://doi.org/10.1029/eo058i003p00156 boffa-balaran, t., liu, j., dubrovinsky, l. s., caracas, r., & crichton, w. (2009). high-pressure ferroelastic phase transition in aluminosilicate hollandite. phys. rev b., 80, 21404. https://doi.org/10.1103/physrevb.80.214104 frost, d. j., poe, b. t., tronnes, r. g., liebske, c., duba, a., & rubie, d. c. (2004). a new large-volume multianvil system, phys. earth planet. inter., 143, 507-514. https://doi.org/10.1016/j.pepi.2004.03.003 jacobsen, s. d. (2006). effect of water on the equation of state of nominally anhydrous minerals. rev. mineralogy and geochemistry, 62, 321-342. https://doi.org/10.2138/rmg.2006.62.14 jacobsen, s. d., hans-josef, r., anastasia, k., & hartmut, a. s. (2005). a gigahertz ultrasonic interferometer for the diamond anvil cell and high-pressure elasticity of some iron-oxide minerals. advances in high-pressure technology for geophysical applications, 2, 25-48. https://doi.org/10.1016/b978-044451979-5.50004-1 knoche, r., webb, s. l., & rubie, d. c. (1997). experimental determination of acoustic wave velocities at earth mantle conditions using a multianvil press. phys. chem. earth, 22, 125-130. https://doi.org/10.1016/s0079-1946(97)00088-8 knoche, r., webb, s., & rubie, d. c. (1998). measurements of acoustic wave velocities at p-t conditions of the earth’s mantle. in m. h. manghnani, y. syono, & t. yagi (eds.), properties of earth & planetary materials at high pressure & temperature (pp. 119-128). https://doi.org/10.1029/gm101p0119 li, b., jackson, i., gasparik, t., & liebermann, r. c. (1996). elastic wave velocity measurement in multi-anvil apparatus to 10 gpa using ultrasonic interferometry. phys. earth planet. interiors, 98, 79-91. https://doi.org/10.1016/s0031-9201(96)03173-1 liebermann, r. c. (1982). elasticity of minerals at high pressure and temperature. in w. schreyer, & e. schweizerbart’sche (eds.), high pressure research in geoscience (pp. 1-14). verlagsbuchhandlung, stuttgart. liebermann, r. c. (2014). history of japan-u.s. high pressure mineral physics seminars: 1976 to 2012. phys. earth planet. interiors, 233, 1-35. https://doi.org/10.1016/j.pepi.2013.06.008 liebermann, r. c. (2019a). the orson anderson era of mineral physics at lamont in the 1960s. minerals, 9(6), 342-360. https://doi.org/10.3390/min9060342 https://doi.org/10.1029/eo058i003p00156 https://doi.org/10.1103/physrevb.80.214104 https://doi.org/10.1016/j.pepi.2004.03.003 https://doi.org/10.2138/rmg.2006.62.14 https://doi.org/10.1016/b978-044451979-5.50004-1 https://doi.org/10.1016/s0079-1946(97)00088-8 https://doi.org/10.1029/gm101p0119 https://doi.org/10.1016/s0031-9201(96)03173-1 https://doi.org/10.1016/j.pepi.2013.06.008 https://doi.org/10.3390/min9060342 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 25 published by scholink inc. liebermann, r. c. (2019b). my career as a mineral physicist at stony brook: 1976-2019. minerals, 9(2), 761. https://doi.org/10.3390/min9120761 liebermann, r. c. (2020). the birth of mineral physics at the anu in the 1970s. minerals, 10(2), 163. https://doi.org/10.3390/min10020163 liebermann, r. c. (2021a). stony brook’s high-pressure laboratory collaborations with french scientists. intl. j. geosciences, 12, 195-212. https://doi.org/10.4236/ijg.2021.123012 liebermann, r. c. (2021b). stony brook’s collaborations with czech scientists. inter. j. geosciences, 12, 487-498. https://doi.org/10.4236/ijg.2021.125026 liebermann, r. c. (2021c). my research collaborations with chinese scientists over the past three decades. inter. j. geosciences, 12, 960-983. https://doi.org/10.4236/ijg.2021.1210050 liebermann, r. c. (2022a). my research connections russian scientists in the past half century. inter. j. geosciences, 13, 155-173. https://doi.org/10.4236/ijg.2022.133009 liebermann, r. c. (2022b). my research connections with english scientists over the past six decades. inter. j. geosciences, 13, 259-267. https://doi.org/10.4236/ijg.2022.133013 liebermann, r. c., chen, g., li, b., gwanmesia, g. d., chen, j., vaughan, m. t., & weidner, d. j. (1998). sound velocity measurements in oxides and silicates at simultaneous high pressures and temperatures using ultrasonic techniques in multi-anvil apparatus in conjunction with synchrotron x-radiation determination of equation of state. the review of high-pressure science & technology, 7, 75-78. https://doi.org/10.4131/jshpreview.7.75 mueller, h. j., schilling, f. r., lathe, c., & lauterjung, j. (2006). recent development of experimental techniques for high-pressure mineral physics under simulated mantle conditions. high pressure res., 26, 529-537. https://doi.org/10.1080/08957950601092606 mueller, h., schilling, f. r., & lathe, c. (2007). multianvil techniques in conjunction with synchrotron radiation at deutsches elektronen synchrotron (desy) — hamburger synchrotron labor (hasylab). geol. soc. am. spec. pap., 421(2007), 207-226. https://doi.org/10.1130/2007.2421(12) speziale, s., marquardt, h., & duffy, t. (2014). brillouin scattering and its application in geosciences. rev. mineral. geochem., 78, 543-603. https://doi.org/10.2138/rmg.2014.78.14 https://doi.org/10.3390/min9120761 https://doi.org/10.3390/min10020163 https://doi.org/10.4236/ijg.2021.123012 https://doi.org/10.4236/ijg.2021.125026 https://doi.org/10.4236/ijg.2021.1210050 https://doi.org/10.4236/ijg.2022.133009 https://doi.org/10.4236/ijg.2022.133013 https://doi.org/10.4131/jshpreview.7.75 https://doi.org/10.1080/08957950601092606 https://doi.org/10.1130/2007.2421(12) https://doi.org/10.2138/rmg.2014.78.14 microsoft word ees-v1n1-p1.doc energy and earth science vol. 1, no. 1, 2018 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 original paper ambient air quality assessment in the grand casablanca area (morocco): impact of road traffic emissions for the 2013-2016 period manal inchaouh1*, kenza khomsi2& pr. mohamed tahiri1 1 department of chemistry, faculty of science ain chock, university hassan ιι of casablanca, morocco 2 direction de météorologie nationale, casablanca, morocco * manal inchaouh, e-mail: inchaouhmanal@gmail.com received: july 31, 2018 accepted: september 5, 2018 online published: september 27, 2018 doi:10.22158/ees.v1n1p1 url: http://dx.doi.org/10.22158/ees.v1n1p1 abstract air pollution is a serious hazard worldwide especially in urban areas. road traffic is the main cause of pollution in agglomerations that are confronted to an excess of pollutants due to traffic intensity and the dominance of diesel cars. this paper presents the assessment of road traffic pollution in the grand casablanca area. data used are the result of simultaneous measurements at thirteen sites located in the grand casablanca. available data cover 4 years period (2013-2016). traffic-related air pollutants are reviewed in order to assess their impact on the local air quality. it include nitrogen dioxide (no2), particulate matter (pm10), carbon monoxide (co) and benzene (c6h6). annual evolutions are presented and compared to national air quality standards; no2 annual trends are also evaluated. the [no]/[no2] emissions ratio calculation allows then to characterize the measurement sites against road traffic. the paper focuses on determining the contribution of road traffic emissions on air quality modifying; we found spatial variability in traffic pollutants. the results pointed out that road traffic and conditions are the main causes of air pollution in the area and the analysis provide a quick view of the relatively critical areas that need more action to reduce this pollution. keywords air quality monitoring, measurements, urban air pollution, traffic intensity, road traffic pollution 1. introduction the urban environment has nowadays the wider population; this generates a perpetual growth of www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 2 published by scholink inc. activities that adversely affect environment, public health, well-being, and quality of life. population increase is accompanied with proportional increase in emissions while higher urbanization rate and lower average household size increase emissions as well (cole & neumayer, 2004). the ever-changing transport sector is exacerbating the phenomenon of pollution and contributing to the overall balance of gas emissions. the transition from massively industrial pollution to a pollution where transports have a predominant share has gradually been accompanied by a major transformation of monitoring systems, while industrial pollution has significantly declined in recent years, transport pollution has been steadily increasing, with the main cause being the increase of cars traffic and the vehicles fleet. air pollution parameters demonstrates a strong correlation with the traffic intensity. the highest correlation indicators established are from co and no2 pollution (zariņš, 2014). moreover, it is in cities that the situation is most sensitive, because while the pollution depends on topography and weather conditions, the consumption of a car in the city is four times higher than on the highway, and the highest pollution levels globally occurs in winter and summer (cichowicz, wielgosiński, & fetter, 2017; dadhich, goyal, & dadhich, 2017). a study on the urban population exposure to air pollution during their travels in the paris agglomeration highlighted that the highest exposure levels are obtained in the passenger cars (delaunay, goupil, ravelomanantsoa, & person, 2012). air pollutants are known or suspected to cause harmful effects on human health, traffic-related pollution proved to be significantly associated with respiratory symptoms in children (kim et al., 2004), moreover, many studies showed that pollution increases mortality and pointed out the causal link between short-term exposure to air pollution and mortality (l. pascal, 2009), (dab et al., 2001). the grand casablanca , morocco’s biggest agglomeration and economic capital, is currently affected by year-round air pollution (khatami, ponche, jabry, & mirabel, 1998). this study has made the first attempt to define the possible influence of road traffic emissions in ambient air quality over a large urban agglomeration from morocco: the coastal area of the grand casablanca. the work carried out in this study focuses on: presenting the main indicators of air pollution originating from road traffic (nox, pm10, co and c6h6), in particular through their effects on health and the environment; present the main associated air quality standards. investigating the temporal trends of no2 concentrations for the period 2013-2016 drawing up a temporal average profiles of sites with the highest levels of pollutants identifying the most affected areas by road traffic pollution by the calculation of [no]/[no2] emissions ratio of each measurement site. analyzing and exploiting data through the boxplots representation of the average cycles determining how meteorological parameters (wind direction and speed) affects the dispersion of pollutants this study can be used in a more general reflection on atmospheric pollution during the implementation of urban travel plan for example. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 3 published by scholink inc. 2. materials and methods 2.1 study area the grand casablanca area (figure 1) is located on the atlantic coast in the north-west of the country, with an area of 1 615 km² and a population of about 4 million inhabitants (rgph 2014). the grand casablanca hosts different activities, a large industrial environment (the thermal power station, mohammedia refinery and ain sebaa-bernoussi industrial zone) characterizes the north-east part, the urbanized part is bordered by the bouskoura forest in the south and rural agricultural lands in the south-east and south-west, the southern parts are less urbanized. it is also a major transport hub for the whole country; railway lines and several major roads and highways connecting the city with the rest of the country cross it: the n1 and n11 national roads, south ring road, coastal road, expressway, r315 regional road and the a7, a3 and a5 highways. figure 1. location of morocco in africa (right map) and location of the grand casablanca in morocco source: haut-commissariat au plan; google maps 2018 2.2 studied parameters and their health impact air pollution parameters considered here (no2, pm10, co and c6h6) are the main indicators of road traffic pollution especially in urban areas. the exhaust (fuel combustion), evaporation, abrasion of vehicle equipment (brakes, tires, etc.) as well as road wear and the resuspension emit these pollutants. nitrogen dioxide (no2) is a motor traffic tracer (l. smith et al., 2015), it forms during the combustion of fossil fuels from the reaction of nitrogen monoxide (no) with oxygen or ozone in the air. no2 causes a range of harmful health effects, a short-term exposure to no2 is associated with adverse health effects and increases hospital admissions and mortality especially for susceptible populations (children, elderly, and asthmatics) and long-term exposure is associated with adverse health effects (respiratory symptoms/diseases, hospital admissions, mortality, etc.) (latza, gerdes, & baur, 2009). particulate matter 10 micron or less (pm10) comes from iron and steel industry, cement factory, wastes incineration www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 4 published by scholink inc. and automobile traffic and the smaller they are, the more dangerous they are (ropeik & gray, 2002). according to a public health study in france, fine particles pollution causes 48,000 deaths per year, which is as much as alcohol, and reduces life expectancy by up to two years (m. pascal et al., 2016). ultra-fine particles provoke alveolar inflammations, with release of mediators capable, in susceptible individuals (elderly, diabetics, or those with known coronary artery disease) of causing exacerbations of lung disease and increasing blood coagulability, thus also explaining the increases in cardiovascular deaths associated with urban pollution episodes (martinelli, olivieri, & girelli, 2013; seaton, macnee, donaldson, & godden, 1995). carbon monoxide (co), an odorless, colorless and flammable gas, results from the incomplete combustion and motor vehicles is the absolutely dominant source (fenger, 1999). numerous studies showed that prolonged exposure to co has health consequences: headaches and dizziness (raaschou-nielsen, nielsen, & gehl, 1995) and elderly hospitalizations for cardiovascular disease (hoek, brunekreef, goldbohm, fischer, & van den brandt, 2002). benzene (c6h6) is a volatile organic compound belonging to the family of hydrocarbons that mainly comes from the residential and tertiary sector, in particular from woods combustion, and road transport. benzene has effects on the nervous system, blood cells and platelets that can cause loss of consciousness and the major health risk associated with exposure to low concentrations has been shown to be cancers risk and leukemia (duarte-davidson, 2001; m. t. smith, 2010; who, 2000). 2.3 data collection hourly data were obtained from the air quality monitoring network of the grand casablanca (13 stations) (see figure 2) from january of 2013 to december of 2016, except for the pm10 that are daily data. the fixed stations are generally located in public places and measures continuously and in real time the concentrations of a number of ambient air pollutants including those quoted above, as well as the meteorological parameters allowing the transformation and dispersion of the pollutants (wind speed and direction, ambient temperature, atmospheric pressure and relative humidity). air pollution parameters studied here are subject to specific regulations in morocco (table 1). in order to perform a relevant statistical analysis, basic data are analyzed according to the requirements of the ademe guide: “rules and recommendations on: data validation, aggregation criteria and statistical parameters” (2003), and the “guide of air quality data aggregation for the application of the european directives 2004/107/ec and 2008/50/ce on ambient air quality” (2015). only sites that meet the criteria mentioned in these guides are evaluated here. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 5 published by scholink inc. figure 2. location of the air quality stations and road infrastructures of the grand casablanca table 1. national ambient air quality standards pollutant nature of the threshold limit values no2 (μg/m3) limit values for health protection 50; annual average 200; percentile 98 of hourly averages limit value for the protection of vegetation 30; annual average so2 (μg/m3) limit values for health protection 125; percentile 99.2 of the daily averages limit value for the protection of ecosystems 20; annual average co (mg/m3) limit values for health protection 10; daily maximum of 8-hour running average pm10 (μg/m3) limit values for health protection 50; percentile 90.4 of the daily averages c6h6 (μg/m3) limit values for health protection 10; annual average 2.4 data analysis for each site of the monitoring network, the mean annual of the traffic pollution indicators: no2, pm10, co and c6h6 were calculated and compared to the moroccan legislated air quality standards, for the entire period 2013–2016. temporal trends of no2 concentrations were then evaluated for stations with a minimum data coverage of 75% of valid data per year for at least three out of the 4-years period. the non–parametric method proposed by thiel (1950) and sen (1968) for estimating the slope of a linear trend was used. this approach involves computing slopes for all the pairs of ordinal time points and then using the median of these slopes as an estimate of the overall slope. since sen’s slope is robust against outliers, it is widely used for the estimation of trending magnitudes of climate series (deo, www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 6 published by scholink inc. mcalpine, syktus, mcgowan, & phinn, 2007; guentchev & winkler, 2010; hidalgo-muñoz, argüeso, gámiz-fortis, esteban-parra, & castro-díez, 2011; tramblay, el adlouni, & servat, 2013). the statistical significance of the obtained trends is then tested using the modified mann–kendall test proposed by hamed and rao (hamed & ramachandra rao, 1998), for testing the presence of a monotonic increasing or decreasing trend. epa’s proucl5.1.002 software (us epa statistical software for environmental applications for data sets with and without non detect observations) was used here and the test is performed at significance level of 5 %. in order to study temporal behaviors of pollutants, temporal profiles are presented in different time steps (monthly, weekly &daily) for sites recording the highest levels of no2, pm10 and co. the most affected sites by road traffic emissions are determined by the method of the no/no2 ratio calculation for characterizing the measurement sites against traffic intensity. a hierarchical classification is carried out and the monitoring sites are grouped according to their profiles. statistical data analysis of pollutants for the site representing the highest [no]/[no2]ratio was performed using the boxplot presentation method for different temporal cycles. boxplot graphic is good for showing trends in the distributions of data (mintz, fitz-simons, & wayland, 1997). we represent the evolution of the minimum, 25th percentile (p25), median, mean, 75th percentile (p75) and the maximum. meteorological data are used for the interpretation of the pollutant concentrations observed at the urban-traffic station representing a traffic pollution hot-spot. meteorological parameters analyzed here include wind direction (°) and wind speed (m/s). 3. results 3.1 annual mean concentrations compared to the annual guideline 3.1.1 nitrogen dioxide no2 the evolution of no2 annual averages (figure 3 (a)) allows the differentiation of the thirteen study sites; it shows that the no2 levels respect relatively the sanitary standard. a prioritization seems to be in place with three sites recording the highest values and exceedances of the limit value for the protection of vegetation (30 μg/m³): ain harrouda, ain sebaa and bouskoura sites. the 98 percentile evolution (figure 3(b)) allows the estimation of peak levels, the measured values are all below the health protection limit value (200μg/m³) except for the ain harrouda site that exceeded this value in 2013. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 7 published by scholink inc. figure 3. evolution of: (a) annual average concentrations & (b) 98% annual percentile of nitrogen dioxide regarding the moroccan standards in the thirteen monitored sites (2013-2016) 3.1.2 particulate matter pm10 for the particulate pollution, figure 4 illustrates the annual evolution of the 90.4 daily percentiles of pm10; most of the represented sites experienced exceedances of the daily pm10 standard. table2 represent the number of days where the pm10 standard was exceeded for the sites presenting exceedances of the health protection. the results shows exceedances of the sanitary standard, and a largest number of overruns recorded in 2014. figure 4. evolution of the 90.4 percentile of daily averages of pm10 regarding the moroccan standards over 2013-2016 period www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 8 published by scholink inc. table 2. number of days exceeding the limit value for health protection of the pm10 (90.4 percentile) st c. ain chock st c. ain harrouda st c. ain sebaa st c. bernoussi st c. bouskoura st c. hay hassani st c. chu st c. oncf st c. wilaya st c. sidi othman st c. jahid st med. khansaa st med. prefecture 2013 2014 40 35 95 37 2015 43 14 2016 13 6 16 3.1.3 carbone monoxide co table 3 record the exceedances of the standard for stations with carbon monoxide analyzers. in 2013-2016 period, the measuring stations showed no exceedances of the 8-hour sanitary standard: 10 mg/m³ (daily maximum of the running average over 8 hours), but in 2016 the station of ain harrouda exceeded the above-mentioned value 17 days. table 3. number of days exceeding the 8-hour co standard (limit value for health protection) st c.ain chock st c.ain harrouda st c.ain sebaa st c. bernoussi st c. bouskoura st c.hay hassani st c.oncf st c.sidi othman 2013 0 0 0 0 0 0 0 0 2014 0 0 0 0 0 0 0 0 2015 0 0 0 0 0 0 0 0 2016 0 17 0 0 0 0 0 0 figure 5. annual average concentrations of benzene regarding the sanitary standard 3.1.4 benzene c6h6 figure 5 shows the evolution of the annual averages of benzene for sites with benzene analyzers. a lack of data probably due to equipment failures for some sites, did not allow to compare the measurement www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 9 published by scholink inc. results or to study the evolution of annual concentrations. however, we found that the recorded levels are all below 10 μg/m3, the annual limit value. 3.2 trends in annual no2 concentrations average trends in data for nitrogen dioxide (no2) were investigated over the period 2013 to 2016 at the grand casablanca monitoring stations. table 4 summarizes the coefficients of variation of theil and sen of the average annual no2 concentrations. the record for six monitoring stations (casa.ain saba; casa.chu; casa.oncf; casa.wilaya; casa.jahid; media prefect; and media khansaa) was less than three. this period is considered too short to offer a meaningful understanding about concentration trends. therefore, results for these stations are not presented in table 4. results indicates statistically significant increasing trends of annual concentrations of no2 at the casa.ain chock; casa.bernoussi; casa.bouskoura; casa.hay hassani and casa.sidi othman stations.trends in casa.ain harrouda station are not statistically significant. table 4. annual trends in nitrogen dioxide (no2) in the studied area; significance level=0.05 station trends average nitrogen dioxide (no2) st c.ain chock 0.215 st c.ain harrouda 0.405 st c.bernoussi 0.0595 st c.bouskoura 0.247 st c.hay hassani 0.202 st c.sidi othman 0.381 3.3 intercycles analysis: average profiles of sites with the highest levels of pollutants figure 6 provide the evolution of automobile pollution indicators studied here, at various time scales (seasonal/monthly, weekly and daily) for sites recording the highest levels of pollution (ain harrouda, ain sebaa and bouskoura). this allows evaluating the temporal evolutions and highlight the occurrence of exceptional air pollution events (pollution peaks, weekend effect, seasonality, etc.) as well as the specificities of this pollution according to the typologies of the measurement sites. temporal profiles enable to differentiate the selected sites and globally shows homogeneous behavior for all pollutants. seasonal/monthly profiles are marked by a maximum in winter (december-february) and minimum values at the end of summer (august-september). weekly profiles shows higher concentrations on workdays and a decline on weekend with peaks in the middle of the week. as for the daily profiles, hourly evolution shows, for no2, the presence of two peaks corresponding to the hours of intensification of car traffic during the day. no2 level increases in the morning from 07:00 to 09:00, a second peak is formed in the late afternoon (19:00-22:00), beyond these hours, levels are stable and www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 10 published by scholink inc. the lowest values are observed at night (23:00-06:00). co daily profile follows the same trend as for no2 but with less intense peaks. for all temporal profiles, the bouskoura site seems to be intermediate to the other sites for all the studied pollutants. figure 6. average cycles (monthly, weekly, daily) of road traffic indicators for sites with the highest levels 3.4 identification of typical traffic sites: [no]/ [no2] ratio considering the results, the[no]/[no2]ratio differs greatly from one site to another (table 5). the resulting values allows to draw a distinction between the sites and to group them in three categories: • ain chock, bernoussi, hay hassani, chu, med khansaa and med prefecture sites are the least influenced by traffic vicinity with an [no]/[no2]ratio lower than 1. these sites could be defined as urban background sites, with an no concentrations mainly lower than no2 and less characteristic of road transport effect. • ain sebaa and oncf sites appears intermediate (moderately affected by road traffic), with an no/no2 ratio of between 1 and 1,5. however, those of ain harrouda, wilaya and sidi othman have more scattered ratios. indeed, in 2013-2014, the sites had ratios lower than 1, then as of 2015, the influence of road traffic emissions seems to have increased to values beyond 1. • finally, bouskoura site stands out as the most affected site by road traffic emissions with an [no]/ [no2] ratio higher than 1.5 for most of the time. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 11 published by scholink inc. 3.5 analysis of the cycle structure: boxplots representation table 5. [no]/ [no2] ratio during the study period (2013-2016) ain chock ain harrouda ain sebaa bernoussi bouskoura hay hassani chu oncf wilaya sidi othman jahid med. khansaa med. prefect 2013 0.83 0.25 -0.56 1.35 0.67 -1.13 -0.61 -0.60 - 2014 0.63 0.86 1.11 0.54 1.94 0.50 -1.01 1.08 0.59 -0.75 0.65 2015 0.55 1.16 0.98 0.56 2.03 0.65 0,63 1.41 1.69 1.06 -0.70 0.78 2016 0.50 1.39 1.11 0.63 2.02 0.49 -1.42 ---0.86 - the box-plot representation of the average cycles allow analyzing the dispersion of the concentration data against the average. it is therefore necessary to analyze the representativity of the average cycles over the considered period. for the bouskoura site, which represents the highest no/no2 ratio, considering the figure, the data are more dispersed in winter than in summer, during the weekly peak (midweek) and peak hours (09:00 and 20:00). the dispersion of the no2 data seems to be better than the co and pm10 data. this observation is illustrated, in part, by the difference between the median and the mean of the extracted cycles (represented by the curve in figure 7). indeed, for the no2 data these are relatively close, whereas for the co and pm10 data the means are sometimes below the median values. the co and pm10 means appear accordingly smoothed by the low extreme values and the no2extreme values are higher than the high border. a specificity is noted with regard to no2 data for the daily cycle, the interquartile gap is larger for hours from 7am to 10am. this can be explained quite simply by the alternation of the road attendance that can vary according to peak hours. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 12 published by scholink inc. figure 7. average cycles (at monthly, weekly, hourly intervals) for the traffic indicator pollutants (no2, co and pm10) of the bouskoura site over the 2013-2016 period 3.6 wind roses figure 8 present the wind roses for the bouskoura site. the wind roses have been created using the hourly data from the four years 2013-2016. the results of this station located in the background of the grand casablanca suggest that the predominant winds come from the northern sector with a velocity mostly between 0 and 2 m/s, followed by the westerly winds; this situation is favorable to the accumulation and stagnation of pollution plumes loaded with air pollutants. the site was therefore influenced by the emissions of pollutants from the center of the agglomeration and the neighboring road network. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 13 published by scholink inc. figure 8. wind roses of bouskoura site from 2013 to 2016 4. discussions the purpose of this study is to examine the role of road traffic in modifying air quality in a large urban agglomeration, the grand casablanca. over all measurement sites, the measured concentrations result from different contributions: background pollution, transregional contribution (imported via air mass flows), urban contribution mainly related to traffic and meteorological factors impact. no2 annual means showed a significant increase for some monitoring sites. the absence of statistical significant tendencies in time series for some monitoring sites is due to the shortness of the period used for this study. the high annual value of no2 in ain harrouda (67.51 μg / m³) can be explained by the exposure of the site to the prevailing winds of the samir oil refinery of mohammedia, and the decrease is probably due to the significant decline of refining activities and their definitive cut by the end of 2014. as for pm10, the majority of sites experienced limit values exceedances most of the time; a large proportion of the particulate pollution can result from road dust resuspension (amato et al., 2009) , and rise with the vehicles speed (nicholson, branson, giess, & cannell, 1989). the benzene and co respects the recommended thresholds except for the station of ain harrouda that exceeds the sanitary standard 17 times in 2016. in order to determine the most affected sites by road traffic emissions, we studied the temporal evolutions of the sites with the highest values of road traffic pollutants, including no2, the analysis of temporal profiles (monthly, weekly and daily) has enabled to understand the evolution of these pollutants over time and highlight the periods with the highest emissions. the no/no2 ratio allowed to set up a hierarchical classification and to determine the most affected sites by the road traffic emissions. the results revealed that the bouskoura site have the highest values and turned out to be the most impacted site by the no2 emissions. this finding may reflects the direct influence of road traffic emissions on the air quality in this site. however, several other factors may be behind these results; in addition to emission levels, meteorological parameters also highly influence the www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 14 published by scholink inc. pollution levels by their transport or transmission (mayer, 2015), a low wind speed (less than 3 m/s) favors the accumulation of the pollutants (latini, grifoni, & passerini, 2002). the analysis of the wind roses in the bouskoura site reveals that the site is mainly subject to the prevailing northern winds, which turns the pollution plumes formed downtown to this site. that can explain the strong values recorded. 5. conclusion urban air quality is getting worse; road traffic in the grand casablanca is largely responsible for the local emissions of nitrogen oxides and particles, and thus contributing to the degradation of its air quality. some air pollutants are present in high concentrations, often above the recommended guidelines. in addition to emissions, air pollution levels also depend on weather conditions. this study allowed us to understand the spatio-temporal distribution of pollutants, particularly those emitted by road traffic in the grand casablanca and to identify the most affected areas by this type of pollution. this work suggests that road traffic plays an important role in the air quality modification, especially in areas with heavy road traffic or close to major traffic routes. the improvement of local air quality requires therefore additional controls and the application of reduction strategies for the vehicular emissions to reduce the alarming pollution levels. declaration of interest the authors report no conflicts of interest. the authors alone are responsible for the content and writing of this article. acknowledgements we want to express our gratitude to the direction de météorologie nationale of casablanca for kindly providing the necessary data. references amato, f., pandolfi, m., escrig, a., querol, x., alastuey, a., pey, j., … hopke, p. k. 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(2013). trends and variability in extreme precipitation www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 17 published by scholink inc. indices over maghreb countries. natural hazards and earth system sciences, 13(12), 3235-3248. https://doi.org/10.5194/nhess-13-3235-2013 treil, h. (1950). a rank-invariant method of linear and polynomial regression analysis. who. (2000). air quality guidelines for europe. environmental science and pollution research, 3(1), 23. https://doi.org/10.1007/bf02986808 zariņš, a. (2014). evaluation of air pollution measurements in urban. construction science, 15(1), 29-34. https://doi.org/http://dx.doi.org/10.2478/cons-2014-0005 microsoft word ees-v2n2-p1.doc energy and earth science vol. 2, no. 2, 2019 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 characterizing land use systems within awoja watershed charles aben1, john james okiror1, jacob godfrey agea1 & esbern friis hansen2 1 department of extension and innovation studies, college of agricultural and environmental sciences, makerere university, kampala, uganda 2 danish institute for international studies, copenhagen, denmark received: april 15, 2019 accepted: june 20, 2019 online published: july 5, 2019 doi:10.22158/ees.v2n2p1 url: http://dx.doi.org/10.22158/ees.v2n2p1 abstract this manuscript analyses trends in land use changes in awoja watershed with the aim of exploring the underlying causes of degradation in this watershed within the context of frequent draughts and floods. changing trends of land use characteristics were used as indicators of ineffectiveness of control of access to resource use in the watershed. the study was carried out in the districts of katakwi, amuria and sorotiin eastern uganda where the watershed is experiencing increasing trends of degradation despite the presence of elaborate watershed management institutions. the study used remote sensing, and focus group discussions to acquire relevant data on land use changes and their perceived causes. perceptions of respondents on the effectiveness of the local governance processes were generated. the findings show increase in built-up areas from 0.21% between 1986-1996; to 3.28 between 2006 and 2016 and a notable decrease in forest cover from 107.48 km2 in 1,986 to 6.94 km2 by 2016. the results also show a dramatic increase in small scale farming area from 629.44 km2 to 2,376.64 km2 from 1986-2016 while the area of wetland reduced from 2,810.47 km2 to 1,355 km2over the same period. results from focus group discussions revealed that although climatic and demographic factors were responsible for land use changes in awoja, control of access to natural resources was inadequate to stop degradation. climatic factors mentioned included increased frequency of floods and draughts that were perceived to have been responsible for changes in vegetation cover, water levels and infrastructure. socio economic factors driving the changes in land use included increased cultivation of wetlands and communal land, increased sale of fuel wood, charcoal and sand, increased migration of cattle herders into the watershed during draughts and out of it during floods and increased fishing. while climatic factors were important, socio political factors such as displacements of communities, resettlements in the fragile environment brought about by government efforts to demarcate wetlands and wild life conservation areas were cited as drivers of degradation. the study concludes that besides climatic factors, inadequate management of access to resources was contributing to degradation of the watershed. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 2 published by scholink inc. keywords watershed management, land use changes, climate change 1. introduction land use/cover changes have now emerged as a global phenomenon and perhaps the most significant regional anthropogenic disturbance to the environment (egeru & majaliwa, 2009). the rate of land use/cover change is high and is escalating globally (krumhanslet al., 2015; palmer, 2009; townsend et al., 2011). africa is said to have the fastest rate of deforestation in the world as a result of over dependence on primary resources (ademiluyi et al., 2008). although the cause for most land use/cover changes is deemed to be population growth (ramankutty et al., 2002b) there are several other interacting factors involved. in egypt, ibrahim and mosben(2015) showed a decline of agricultural land while in india, land use cover change of 88.8% was due to increase in built up area. in essence both land use/cover changes are products of prevailing interacting natural and anthropogenic processes. land use/cover change detection allows for the identification of major processes of change (fasona & omojola, 2005). traditionally, local institutions have been instrumental in safeguarding resources, including the protection of forests and watersheds (agrawal, 2010). in uganda today, the role of institutions has been enhanced by decentralization of natural resource management. this has empowered district land offices, fisheries offices, agriculture of forestry officials with facilities and resource protection enforcement tools (mlg report, 2017). in the face of climate change therefore, institutions are profoundly influencing implementation of adaptation to climate change, an idea also supported by agrawal et al. (2009) when he notes that institutions have been instrumental in facilitating adaptation and channeling external resources. it should be noted however that where climate change adaptation measures have given less attention to social and institutional alternatives the impact of climate change amplifies existing unfavourable conditions (mccarthy et al., 2001) and resources are prone to exploitation because of the compromise that arises in the resource governing institutions. global narratives on natural resource governance point to struggles of local governments with implementation of climate change adaptation policies (agrawl et al., 2013, nam et al., 2015). various scholars have shown that management of environmental resources largely neglects complexity and the human dimension (holling & meffe, 1996; ludwig, 2001; gleick, 2003; pahl-wostl, 1995, 2007 a, b, c). uncontrolled cultivation and unsustainable harvesting of resources with corresponding influences in fragile watershed areas are some of the main human activities escalating environmental degradation (ministry of water and environment, 2013). despite the presence of elaborate governance infrastructure composed of local government, ngos and local environmental committees, awoja watershed in kyoga water management zone of eastern uganda with an area of 10.281 km2is a key watershed degradation hotspot with a perceived degradation rate of 76% as compared to 63% from lake victoria crescent and 41% in the south western farmlands www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 3 published by scholink inc. of uganda (nema, 2008; turyahabwe et al., 2013). with increasing frequency of floods and draughts increasing degradation in this watershed threaten the sustainability of the social and ecological system in the region. virtually no part of awoja watershed has remained untouched by the community’s compulsion to transform nature and livelihoods in order to survive changing climatic conditions. as noted by (turyahabwe et al., 2013; qingqing, 2015; junguo et al., 2016) in akello et al. (2016), population growth, increased conflict on resource use and limited alternatives are some of the factors fueling land use changes in the lake kyoga basin of which awoja is part. however, little is known about the constraints posed by local interest factors on sustainable management of this watershed. as local institutions strive to manage and control access to natural resources in awoja; local political, economic and social interests appear to be getting in the way leading to uncontrolled access to natural resources within the watershed. within awoja watershed in eastern uganda little is known on the magnitude, extent and level of land use cover change (de leeuw, 2016; mbogga, 2014; mutengeka et al., 2013). while recent studies have underscored the importance of quality of participation and information dissemination in watershed restoration, (akello et al., 2017) little is known about the local influences and the human factors escalating the degradation of this watershed. this study sought to relate land use change to the governance of resource us in the watershed. owing to the fact that land use changes are not a consequence of climate change effects alone, characterizing the changes was important in order to unravel the causes of degradation as it went much beyond technologies and emphasized amalgamating technological tools with broad-ranging political, social and economic factors. 2. materials and methods 2.1 research design the study applied a cross sectional survey research design. according to amin (2005), a cross sectional survey is such study that is carried out at one point in time. the design employed both the qualitative and quantitative approaches to allow triangulation in data collection and data analysis that helped the researcher to obtain quality results. the approach of triangulation in a cross sectional research design was also supported by amin (2005), as viable in generating quality results. 2.2 the study area this study was conducted in amuria, katakwi and soroti districts, in awoja watershed of eastern uganda where draughts and floods have become frequent in the last decades. the watershed has experienced a high degradation rate of about 20% in the last two decades of about 20%, which is much higher than the national average of 11% (mwe 2013). soroti district was purposively selected because it is host to the awoja wetlands where the greater part of the awoja watershed lies. administratively soroti has been the mother district from where most of the districts in teso have been curved. therefore it is most endowed with historical information on the www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 4 published by scholink inc. watershed. katakwi was selected because of its trans boundary interactions with karamoja sub region and their struggles for common pool resources such as water and pasture during floods and draughts. amuria district was selected due to its vulnerability to floods. amuria is also the only district in teso sub region that comprehensively implemented wetlands policy including the government interventions of wetlands demarcation and legislation. gweri sub county in soroti was selected due to its experiences with controversies surrounding wetlands encroachment; rice production and jica rice interventions in awoja wetlands while magoro sub county in katakwi was purposively selected because of flood vulnerability and its struggles with uganda wild life authority (uwa) on demarcation of game reserves. wera sub county and the two parishes of morungatuny and okile in amuria were selected because of their participation in the wetlands demarcation program by amuria district local government. the communities in the sample area are mainly agro-pastoralists, practicing the teso farming system characterized by both crop production and livestock rearing. these areas suffer from similar incidents of flooding, draughts and displacements but vary widely in their water and land resource endowments and utilization. they also differ in the extent of implementing of natural resource laws and regulations. the sub-region experiences bi-modal type of rainfall and crop production is by far rain-fed. the crop production cycle follows the pattern of rainfall on annual basis. the average rainfall is 1,200mm per annum. the vegetation of the sub-region can best be described as grassland-savanna predominated by grassland and shrubs. the soils are mainly sandy loam with variation from sandy to loamy soils depending on the terrain. 2.3 data collection and analysis a) remote sensing thematic classification of multispectral images was adopted to assess land use systems and cover changes in awoja watershed. image classification was performed, where satellite images were converted into thematic data. the process involved compressing a mosaic of pixels that belong to a common and relatively homogeneous class into one theme. the intention of image classification was to ease the analysis of thematic characteristics of some environmental features like land use/land cover within the gis-basedmodeling. the administrative boundary of the study area was projected to universal transverse mercator (utm) projection in zone 36 north and datum of world geodetic system (wgs 1984), same to that of the imageries. the administrative layer was used for clipping the imagery scene to the study area extent. the information generated was mainly based on analyses of land use changes as shown by results of gis maps generated over 10 year intervals. the images were accessed from u.s. geological survey provided through web portal of earth explorer (https://earthexplorer.usgs.gov/). pre-processing and classification of land sat images were carried out by using harris envi 5.3 software. standard methods, which included the use of image elements like tone, texture, shape, location, association, pattern, etc., of digital image processing were adopted for thematic land use land cover mapping. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 5 published by scholink inc. training signatures were developed aided by google imagery at 5m spatial resolution obtained from portable basemap server (https://geopbs.codeplex.com/) within the arcgis software. with the high-resolution image, training samples were collected, evaluated, edited to create the training data (signature file) for use in the land use land cover classification. ground truth points collected using the gps was extracted into shape file data format using dnrgps application version 6.1.0.6. figure 1. remote sensing methodology b) documents review this involved a comprehensive literature review to capture information on legal, policy, administrative and implementation frameworks related to natural resource management at local government levels. it also reviewed relevant information and other studies from various sources. some of the documents reviewed included: the national climate change policy (nccp, 2012), the local government act (1997), the decentralization policy, wetlands protection act, development plans, annual budgets, monitoring and evaluation reports and many others. c) key informant interviews this was used to collect primary data that was used to evaluate the policy development processes, including the principles in the framing of policies governing natural resource management. the tool was also used to measure variations between policy frameworks and real governance practices of www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 6 published by scholink inc. natural resource management in a changing climate and influence of stakeholders on institutional practice. face-to-face/one-on-one interviews with civic leaders and leaders of ngos involved in adaptation to climate change were carried out to achieve the above. semi structured questionnaires were used due to their flexibility to probe for details. inputs from people at various levels of governance, local government technical (sub county: senior assistant secretaries, parish chiefs, environment focal point officers, and political wing (lc iii chairperson, councilors, and members of the sub-county executive). information was also collected from csos and extra local institutions (members of parish development committees and members of disaster risk management committees) d) focus group discussions this was organized at each sampled parish from all three sub counties under study. in all 6 fgds were carried out. each fgd had at least 8-12 people selected with the help of local government and ngo partners at the sub county. efforts were made to cover variations among women, youth and the elderly. this was meant to measure community perceptions on local participation in resource management. it was also used to measure social inclusiveness of policies, and institutions governing adaptation in the study area. secondly, fgds were conducted at institutional levels to determine the organization profiles, institutional linkages, institutional interactions and changes in policy and practice among institutions involved in adaptation to climate change. 3. results the findings are presented starting with a description of the key land use systems in awoja watershed, recent changes in land use patterns in the watershed, the key drivers of these changes and the implications for sustainability in this watershed are presented. 3.1 quantification of key land use system in awoja figure 2 shows the subsequent land use cover maps for 1986, 1996, 2006 and 2016which had an overall map accuracy of 90.2%, 89.2%, 90% and 80%respectively for all the images by using the error matrix. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 7 published by scholink inc. figure 2. trends in land use cover changes from 1986-2016 this approach has been popular in evaluating per-pixel classification (lu & weng, 2007) kappa statistics were also computed for each classified map to measure the accuracy of the results for the three years giving 0.881, 0.839, 0.883 and 0.791 for the above years respectively. the overall results are viable for subsequent analysis and change detection (lea & curtis, 2010). table 1 shows the quantification of land use/cover over four decades from 1986-2016. the main land use types include grasslands covering 32.8% in 1986 but down to 27.81% in 2016; woodlands at 1986 1996 2006 2016 www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 8 published by scholink inc. 19.10% coverage in 1986 and 20.55% in 2016. the built up areas covered is 18.9% km2 in 1986 representing 0.21% and 296.21 km2, representing 3.28% in 2016. the area covered by wetlands was substantive at 2,810.87equivalent to 30.85% in 1986 but had reduced to 1,353.03 km2 equivalent to 14.85% by 2016. table 1. quantification of land use/cover (1986-2016) 1986 1996 2006 2016 landcover type area (km2) % area (km2) % area (km2) % area (km2) % built up areas 18.9 0.21 43.71 0.48 146.64 1.59 298.61 3.28 woodland 1740.43 19.1 1863.64 20.46 2143.73 23.23 1872.36 20.55 forest 107.48 1.18 95.47 1.05 49.99 0.54 6.94 0.08 grassland 2988.42 32.8 3124.55 34.3 2579.18 27.94 2533.57 27.81 open water 814.58 8.94 729.14 8 635.92 6.89 669.25 7.35 small scale farming 629.44 6.91 865.09 9.5 1659.46 17.98 2376.64 26.09 wetland 2810.87 30.85 2388.67 26.22 2015.28 21.83 1353.03 14.85 figure 3 shows a graphical representation of the percentage coverage of land use types in awoja watershed described above. figure 3. graphical representation of land use cover in awoja watershed 1986-2016 3.2 land use cover changes table 4.2 shows the dynamic changes in land use/cover types from the period 1986 to 2016. the table indicates an increase in built areas from 0.3% between 1986-1996; to 1.7% between 2006 and 2016. there is a notable decrease in forest cover from 107.48 km2 to 6.94 km2by 2016. the table also shows www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 9 published by scholink inc. a dramatic increase in small scale farming area from 629.44 km2 to 2,376.64 km2from 1986-2016 while the area of wetland reduced from 2810.47 km2 to 1,355 km2over the same period. it can also be seen from the table that the area covered by open water has reduced from 814.58 km2 to 669.25 km2 between 1986-2016. the quantified changes in square kilometers and the percentage change in area is presented on table 2. the table indicates that the area covered by forests continued to decline from 1986-2016. it can also be seen from the table that despite positive changes in the land area between 1986-1996, the area covered by woodlands also declined over the last 2 decades; between 1996-2016. table 2. land use systems and cover change statistics 1986 to 1996 1996 to 2006 2006 to 2016 land use land cover area (sq km) % area (sq km) % area (sq km) % built-up areas 24.8 0.3 102.9 1.1 152.0 1.7 woodland 123.2 1.4 280.1 3.1 -271.4 -3.0 forest -12.0 -0.1 -45.5 -0.5 -43.1 -0.5 grassland 136.1 1.5 -545.4 -6.0 -45.6 -0.5 open water -85.4 -0.9 -93.2 -1.0 33.3 0.4 small scale farming 235.6 2.6 789.4 8.7 722.2 7.9 wetland -422.2 -4.6 -488.4 -5.4 -547.3 -6.0 figure 4 shows a graphical representation of the percentage changes in land use in awoja watershed over the period 1986-2016. as shown, there was continued reduction in the wetlands area all through 1986-1996, 1996-2006 and 2006-2016. the built up area of the watershed continued to increase all through the period 1986-2016. the area covered by grassland that had increased between 1986-1996, declined from 1996-2016, while the area covered by forests continued to decline all through the period from 1986-2016. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 10 published by scholink inc. key: -above 0% depicts positive changes in land use type -below 0% depicts negative changes in land use type figure 4. changes in land use in awoja watershed 3.3 drivers for land use changes in awoja watershed land use changes in the watershed were a result of inadequate control of access to resources, which can be linked to the local political, social and economic factors. results from the household survey showed some of the major factors responsible for the escalation of land use changes. close to equal proportions of respondents (32.8% and 30%) felt that there is overgrazing in the wetlands and that wetlands have been highly encroached. 29% felt that there was over cultivation and increased access to wetland resources, while 8% felt that the forests have been cleared. table 3. perception of respondents on changes in land use and control (n=180) how demand for land has affected protection of wetlands (%) cum. forests have been cleared 7.78 7.78 over cultivation and increased access to wetlands 29.44 37.22 there is over grazing in wetlands 32.78 70.00 wetlands have been highly encroached 30.00 100.00 total 100.00 from the kii technical staff from environment department indicated that there was reluctance for the local government administrative and political staff to control access to wetlands resources and that www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 11 published by scholink inc. some of the leaders were also involved in wetlands cultivation. politicians were also reported to be lenient to the population in order protect their votes. participants in focus group discussions identified a number of factors that were considered drivers of land use changes observed within the watershed as presented on table 4.4. secondary data from fieldwork of the climate change and rural institutions ccri project was also used to corroborate the data obtained. the participants mentioned six major drivers of land use change in awoja watershed, which were categorized into four main types namely: climatic, demographic, policy and socio economic factors. climatic factors include increased frequency of floods and draughts that were perceived to have been responsible for changes in vegetation cover, water levels and infrastructure. from the household survey all the respondents ever experienced floods or draughts. however, 46% and 44% of the respondents were adversely affected by the problems of floods and draughts respectively. demographic factors comprised of increase in population and population distribution and migration were perceived to have been responsible for increase in built areas, reduced land for cultivation and increasing resource use conflicts. 30% and 41% of the respondents reported the problem of loss of land and land conflicts respectively. table 4. perceived drivers of land use changes in awoja observed changes driver reduced vegetation cover increased wetlands cultivation reduced water availability increasing frequency of droughts increase in water coverage displacements of communities and emergence of camps reduction in land for cultivation destruction of infrastructure: roads, schools, health centres increasing frequency of floods increased in built areas increased small scale farming land fragmentation reduced forests, woodlands and vegetation cover reduced communal land area increasing population increased cultivation in uplands, displacements from wildlife areas to wetlands in magoro, restrictions in cutting of endangered tree species, promotion of some enterprises e.g upland rice. government interventions (land demarcation for conservation) www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 12 published by scholink inc. increase in built areas, increasing demand for fuel wood, decreasing water resources migration of agro pastoralists communities increased cultivation in wetlands, emergence of new enterprises such as piggery, and charcoal burning. socio economic pressures government interventions mainly in the form of demarcation of wetlands and conservation areas were perceived to have been responsible for displacement and evictions from traditional cultivation areas. farmers mentioned that demarcation had marginalized cultivators and benefited livestock farmers who were being allowed to graze their animals in the wetlands after the demarcation. from the fgd, a local leader of omugenya in gweri sub-county in soroti district pointed out that “overgrazing by cattle keepers some of who come from outside the district had led to degradation of the gweri wetlands” below is a detailed presentation on mobility as a cause of land use changes in the watershed. figure 5. mobility as a driver to land use changes figure 5 indicates the mobility patterns within awoja watershed in a changing climate. during heavy rains, because of floods, the cattle keepers move from lowlands to uplands and when there is drought www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 13 published by scholink inc. they return to the lowlands. this has significant effects on other enterprises in the uplands wherethere is intense competition with cattle keepers for grazing land. it was also noted that during floods, some community members who reside in low lands move to internally displaced peoples camps or even to homes of relatives in uplands. this creates a number of social and economic challenges that lead to compromises in enforcing rules governing resources use. it was revealed during interviews that whenever people moved from one place to another because of climate change, some never went back because they take up new income generating alternatives and others move to urban centers where they hide and do not want to come back to the villages. it was further revealed that the climate mobility was happening in all districts within the awoja region and the impact on resources use had been the resulting land use changes that are a further challenge in awoja watershed. finally, socio economic pressures including food security needs, family incomes and social needs were deemed to have created competition for resources leading to increased cultivation of wetlands and monetization of rice and charcoal burning, sand mining and other natural resources. from the household survey, 46% and 39% of the respondents were involved in commercial charcoal burning and selling of fuel wood respectively. further, 48%, 21% and 14% were encroaching on the wetlands for purposes of fishing and rice growing, cutting grass for thatching and grazing of animals respectively. 85% of the respondents were involved in sand mining. 3.4 implications of land use changes for sustainability respondents’ views on the implications of land use changes for the sustainability of the ecological and social system in awoja watershed is shown in table 5. table 5. respondents views on the implications of land use change for sustainability land use change % of respondents implications for sustainability increased cultivation of communal land 14.0 access denied for other users, resource governance rules compromised. increased fishing involving both men and women 47.9 survival of some fish species threatened increasing rice cultivation in the wetlands 47.9 wetlands degradation (siltation, over flooding) sand mining in the watershed 85.0 water logging, harbors diseases agents such as mosquitoes, destroys landscapes increasing sale of fuel wood and charcoal by both men and women 84.7 deforestation and alteration of the water cycle. increasing livestock numbers 13.6 overgrazing in the wetlands, destruction of bird roosting www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 14 published by scholink inc. grazing in the wetlands sites, uncontrolled burning to generate new pasture destroys bird roosting sites at the swamp fringes, accumulation of livestock diseases the respondents mentioned threats to the ecological system posed by increasing cultivation in the wetlands as well as cattle grazing in both the wetlands and uplands in the swamp fringes. cattle grazing and upland farming activities are perceived to have resulted in increased soil erosion into the wetlands. increased sedimentation to the wetlands has affected the water levels as well as fish habitats in the downstream. increasing use of illegal fishing methods, increased sale of fuel wood and charcoal, sand mining and increasing encroachments on the ramsar sites all pose threats to the ecological system as forest and fish resources get depleted and breeding sites of important bird species in the ramsar sites are destroyed. respondents also mentioned that increased grabbing of communal land by individuals and families nearest to them denied access for some community members. it was mentioned that some individuals annex, cultivate and or fence off communal grazing areas and cattle tracks and routes to water sources. keeping large numbers of cattle and goats was also mentioned as a risk to crops especially cassava. it was mentioned that during dry conditions when pasture is inadequate, most livestock especially goats are left to wonder on free range and end up destroying crops in the field. consequently, the communities have adopted the practice of sending all animals to the wetlands in a sort of free-range -community-ranching system. 4. discussion of results the research findings show how the land use systems in awoja watershed have been changing over the last 3 decades 1986-2016.these spatial and temporal changes are discussed in the context of political ecology of watershed management in a changing climate. the notable changes in the last decade has been the reduction in the wetlands, an increase in built area, an increase in small scale agriculture, a reduction in the forest cover, a reduction in the wood land and an increase in built up area. whereas the open water area had decreased between 1986 and 1996 as well as from 1996-2006, there was an increase in open water area between 2006 and 2016 the trend shows an increasing recovery of open water area. this trend depicts an increase in human activity on the two major lakes bisina and opeta and the rivers that feed them. all these changes have occurred despite the presence of environment and climate change management institutions and signify the need to in contribution of the human agency in watershed degradation as well as the struggles of local institutions with the management of natural resources in a changing climate. the findings also show an increase in small scale farming comprising by small plots of between 0.5 to www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 15 published by scholink inc. 1 acre, which characterize land fragmentation. increase in small scale agricultural area has been at the expense of forests, woodlands and wetlands. the influence of population pressure on land use for agriculture is consistent with the views of keter (2011), who argued that the social economic activities of an area are highly influenced by the type of population in that area. gebreyesus and kirubel (2009) reported that the heavy reliance of some 85 percent of ethiopia’s growing population on an exploitative kind of subsistence agriculture is a major reason behind the current state of land degradation. in awoja a higher population growth rate is pushing people to use all the land available including those within the proximity of the rivers, the lakes and the wetlands, which is not a good signal. the findings are in line with kaggwa et al. (2009) who found that agriculture was the principal cause of watershed degradation. land fragmentation has arisen from increasing population and traditional practice of dividing land among the children. while increasing birth rates and climate induced migration appears to have an influence on land use in awoja watershed, control of access to environmental resources will play a big role in environmental protection. this suggests that while any land use improvement policy must focus on tackling both the birth rate challenge and the climate change effects in order to strike a land use equilibrium that is sustainable, policy implementation should emphasize compliance and plan to curb political processes that weaken control of access to the resources. 5. conclusions and recommendations the major characteristics of land use changes in awoja depict the effects of climate change and human activity and the weakness of institutions in controlling access and use of natural resources as shown by decrease of forest cover, decrease in wetland areas and increase of built up areas. the key conclusion in this study is that there is an increasing trend of land degradation in awoja watershed as seen from the period 1986-2016, which needs to be curbed. while the land use changes are perceived to be due to population and climate change pressures, there is need to focus on the control of access to environmental resources in this watershed. therefore, a good analysis of the local institutional factors catalyzing the degradation of the watershed in required in order to design appropriate management program for the watershed. the results also indicated the forest cover has reduced because of human activity and this has contributed greatly to changes in weather conditions including long drought periods and heavy rains leading to flooding in the watershed. the role of institutions has been characterized with compromises which limit the capacity to enforce the rules governing resources use in the watershed. generally, the study concludes that degradation in the watershed is vivid and is as much a result of increased human activity brought about by climate change. in view of the findings it is recommended that diversification of income sources that draws away communities from over reliance on the awoja watershed resources is essential. this would include adoption of low risk but high yielding enterprises such as fruit production and tree planting in the uplands. the other recommendation is that local governments need to sensitize the community on the www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 16 published by scholink inc. gravity of the current trends of degradation and enact bylaws to control the human causes of degradation of awoja watershed particularly the current uncontrolled access to wetlands for rice cultivation and over fishing as well as deforestation. references akello, s., turyahabwe, n., okullo, p., & agea, j. g. (2016). changes in land use/cover change and perceived status of awoja in eastern uganda. african journal of environmental science and technology, 10(11), 406-414. https://doi.org/10.5897/ajest2016.2136 amin, m. e. (2005). social science research: conception methodology and analysis. kampala: makerere university printeryafd. de leeuw, j. (2016). trees and watershed management in karamoja, uganda. evidence on demand. climate & environment, infrastructure and livelihoods. a quick desk study commissioned by dfid uganda. gebreyesus, b., & kirubel, m. (2009). estimating soil loss using universal soil loss equation (usle) for soil conservation planning at medego watershed, northern ethiopia. journal of american science, 5(1), 5869 ibrahim, r. h., & mosben, r. k. (2015). monitoring urban growth and land use change detection with gis and remote sensing techniques in dagahlia governorate egypt. ipcc. (2007a). climate change 2007: the physical science basis. contribution of working group i to the fourth assessment report of the intergovernmental panel on climate change. krumhansl, k., jamieson, r., & krkosek, w. (2016). using species traits to assess human impacts near shore benithic ecosystem in the canadian artic. canada. ecol. indic., 60, 495-502. https://doi.org/10.1016/j.ecolind.2015.07.026 leach, m., & mearns, r. (1996). the lie of the land: challenging received wisdom on the african environment. oxford: james currey; portsmouth, nh: heinemann. mbogga, m., malesu, m., & de, leeuw, j. (2014). trees and watershed management in karamoja, uganda (vol 4, p. 25). evidence on demand, uk. https://doi.org/10.12774/eod_hd.december2014.mboggametal ministry of water and environment. (2013). the national forest plan 2011/12-2021/22.directorate of environment affairs, kampala. mugende, o. m., & mugenda, a. g. m (1999). research methods. nairobi: african center fortechnology studies press. palmer, m. a. (2009). reforming watershed restoration: science in need of application and applications in need of science. estuaries coasts, 32, 1-17. https://doi.org/10.1007/s12237-008-9129-5 the constitution of the republic of uganda. (1995). the ministry of justice and constitutional affairs, kampala-uganda www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 17 published by scholink inc. townsend, p. v., harper, r. j., brennan, p. d., dean, c., wu, s., smettem, k. r. j., & cook, s. e. (2011). multiple environmental services as an opportunity for watershed restoration. for policy econ., 17, 45-58. https://doi.org/10.1016/j.forpol.2011.06.008 energy and earth science vol. 6, no. 1, 2023 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 original paper comparing smoked fish quality of traditional and improved modern ovens using dendro-energy from mangrove and tropical forest woods and implications for conservation in central african atlantic coast, cameroon gordon n. ajonina 1,2* , coleen mumbang 2,3 , jacqueline therese ngo oum 1 , fani momo dogmo 1 , minette tomedi eyango 1 & francois tchoumbougnang 1 1 institute of fisheries and aquatic sciences, university of douala (yabassi), p.o. box 7236 douala, cameroon 2 cameroon wildlife conservation society, cwcs coastal forests, mangrove & marine programme, bp 54 mouanko, littoral region, cameroon 3 faculty of sciences, department of plant sciences, university of buea, p.o. box 63 buea, cameroon received: december 1, 2022 accepted: december 13, 2022 online published: february 11, 2023 doi:10.22158/ees.v6n1p1 url: http://dx.doi.org/10.22158/ees.v6n1p1 abstract smoked fish qualitative organoleptic parameters (color, smell, texture and taste) and quantitative proximate parameters (protein and ash content and salt mineral: ca, iron, mg, zn content in ash) of two species (ethmalosa fimbriata and pseudotolithus elongatus) smoked in traditional and modern ovens with wood from mangrove (rhizophora racemosa) and two tropical forest (sacoglottis gabonensis and albizia glaberrina) species in douala-edea atlantic coast, cameroon are presented. women processors significantly spend more time, consume more wood and consequently release significant amount of carbon dioxide (co2) to the environment with traditional smoking system. organoleptic characteristics were significantly different with ovens types but not with different wood species except color (black and marron from inland forest wood species and preferred brownish and golden brown colored smoked fish from mangrove wood). fish food constituents yielded for improved smoked oven: protein content (65.52%; 69.45%), ash content (6.21%; 5.57%) and traditional oven: protein content (70.65%; 75.00%), ash content (5.73%; 6.33%) for ethmalosa fimbriata and pseudotolithus elongatus respectively. results also confirmed good dietary quality of fish samples www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 2 published by scholink inc. (source of calcium, iron and magnesium). some energy efficient management techniques and conservation implications were proposed regarding qualitative and quantitative improvement of smoked fish. keywords dendro-energy, smoked fish, smoke ovens, mangrove and inland tropical forest woods, conservation, cameroon 1. introduction in cameroon, fish accounts for 49% of the diet as a source of protein of animal origin in households. its importance is even greater among the poorest segments of the population (minagri, 2002). imports of this foodstuff have been estimated at more than 80,000 tons per year in an attempt to supplement fisheries production of 120,000 tons in 2002 (fao, 2004). on the basis of per capita consumption estimated at 16kg before the devaluation in 1992, current annual demand would exceed 280,000 tons. in addition, fish remains a highly perishable commodity after capture, hence the need to improve preservation techniques, particularly smoking. this method of conservation probably dates back to prehistoric times and is one of the oldest known methods of preserving fish products after drying and salting (knockaert, 1990). today, smoking is the only widely used means of preserving fishery resources in the douala-edea central african coastal atlantic area. according to the results of work carried out by the cameroon wildlife conservation society (cwcs), a national non-governmental organization working since 1997 in the area conducting studies and community based conservation activities to develop a participative management plan, in 2009, this fish smoking activity occupies entirely the women of the area. these women make extensive use of traditional smokehouses (figure 1, table 1), smoking more than 1,000 tons of fish per year and sell them mainly to the large cities of douala, yaoundé and western cameroon through intermediaries’ women called “bayam-sellam”. furthermore, traditional smokehouses have serious health and environmental concerns in the area (ajonina et al., 2005). they are responsible for diseases such as cancer, headaches, eye ailments and the annual clearing of more than 140 ha of mangrove forest, hence the need for efficient wood bio-energy use management through the improved smokehouses set up by cwcs in early 2000s in the douala-edea area (ajonina & eyabi, 2002; feka et al., 2009). since the establishment of this innovative improved smokehouse initiative with partners (forkam et al., 2020), some sensitization and training campaigns have been conducted to enhance the use and adoption of the new technology approved by the cameroonian government that featured as one of the projects under validation in the clean development mechanism (cdm) (cdm-onfi-cwcs, 2009). www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 3 published by scholink inc. traditional ovens chorkor smoke oven hybrid smoke oven figure 1. types of smoke ovens commonly used www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 4 published by scholink inc. table 1. comparison of some commonly used fish smoking ovens oven type construction materials performances fish smoking time (hours) wood consumption (m 3 ) control of operations construction cost (us $) product quality references traditional planks, nails, meshes 3-4 1.4 difficult 15 000 brilliant (feka et al., 2009) marion (2009) eyabi (1994) improved oven with local material planks, nails, sand, meshes, corrugated iron sheets 5-8 0.9 easy 32 500 good (feka et al., 2009) marion (2009) eyabi (1994) hybrid oven (chockor) sun dry bricks, sand, nails , meshes 10-18 1.0 easy 17 500 good eyabi (1994) eyabi (2010) this study was motivated with main objective to better appreciate the extent of this innovation from existing tradition ovens and the preference to certain species of wood used in both oven types especially mangrove wood with respect to other inland tropical woods with not yet scientific evidence and their implications on the quality of the final product, smoked fish. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 5 published by scholink inc. 2. materials and methods site description figure 2. map showing the study village communities the study coastal village communities (yoyo 1 & yoyo 2) are within the buffer zone of the newly regazetted douala-edea national park (denp) in 2018 from old wildlife reserve, situated some 75 km south west of douala city, cameroon’s economic capital. in the districts of mouanko and manoka in the littoral region within the douala-kribi basin of the coastal atlantic ocean (latitude 3° 14’ 3°50’n and longitude (9°34’-10°03’ e). covers an area of about 300,000 ha with more than 50% terrestrial and less than 50% marine area stretching for over 100 km along the cameroon coastline (figure 2). the region has an equatorial climate type, characterized by abundant rains (3,000-4,000 mm) and high temperatures with a monthly average range of (24-29) o c. these conditions have favored the www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 6 published by scholink inc. development of many diverse habitats spanning terrestrial, marine, river and lake ecosystems with diverse sites of both terrestrial and aquatic species. wildlife populations and other natural resources of newly created national park are continuously threatened by hunting, bush meat trade and habitat destruction as result of increase human population in the area including oil-gas exploration and exploitation activities in some sections (though this has stopped with creation of national park in 2018). the humid forests and mangrove vegetation is of high biological value that serves as a refuge for many resident and seasonal migratory birds of over 80 species (ajonina et al., 2020). the coastal forest is also made up of 40 000 ha of giant mangrove forest (about 20% of the total mangrove stands in cameroon) with max diameter 120 cm and max height of 60m of seven plant species, with the dominant species rhizophora racemosa and avicennia germinans clearly displaying a spatial zonation pattern (ajonina, 2008; ajonina et al., 2014; ajonina, 2022). in addition, the park also hosts a varying number of vegetation types, amongst which are freshwater swamps and degraded primary forest. the park was regazetted due to threat and encroachments and over-exploitation coupled with the lack and/or poor enforcement of policies since its creation initially as a wildlife reserve in 1932 essentially terrestrial to put exploited areas and over 40 communities as buffer zones and marine extension compensation zone of over 140 000 ha. this vast marine park, the first of its kind in cameroon is the fifth largest in western africa. the park is also important for the reproduction of several cetaceans, manatees, and marine turtles (fretey, 2021). the major economic activity is fishing, and about 500 tons of fish are harvested annually by the two fishing localities in which this study was conducted (cwcs, 2001). mobilizing participants and experimental materials to better own the results of this study, participatory process approach (forkom et al., 2020) was adopted by cwcs to conduct this experimentation through organizing three major formal meetings. the first meeting was a planning meeting with the relevant technical departments where the experimental design (figure 3) was explained to participants. the second meetings then mobilized all stakeholders involved in smoking in the study fishing communities with assignment of different tasks to the technical services concerned: the conservation service for wood supply responsibility for the provision of the inland tropical species (sacoglottis gabonensis “bidou” and albizia glaberrina “essate”); supply of fish by the department of fisheries making contacts with fishermen to provide the two species of fish ethmalosa fimbriata “bonga” and pseudotolithus elongates “bosu”). to sensitize the population on the environmental and socio-economic benefits of outcome of the experiment, the third meeting was organized chaired by the district head bringing together all parties concerned including the technical services, traditional leaders and the population especially the participants of the villages selected for the experiment. having sensitized the stakeholders, a measured of wood and fish species was then distributed to 24 fishing smoking ovens having both traditional and modern ovens with each woman assisted by an observer who recorded the information (quantity of wood used, www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 7 published by scholink inc. smoking time, etc. ...) as the process went on. experimental structure the experimental structure was consolidated as a 2×3×2 factorial arrangement with 2 types of smokehouses (traditional oven, modern oven), 3 types of wood species (mangrove: rhizophora spp “matanda” and inland rainforest species: sacoglottis gabonensis “bidou” and albizia glaberrina “essack”) and 2 types of fish species (ethmalosa fimbriata “bonga” and pseudotolithus elongates “bosu” and four replications per treatment (figure 3) though fourth replication with the second fish species, pseudotholithus elongates could not be possible because of the rarity of the species. figure 3. 2x3x2 experimental model to compare effects of wood sources and fish smoking oven types on some smoked fish parameters www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 8 published by scholink inc. data collection in collaboration with cwcs staff and technical services, smokers were monitored throughout the smoking operation by recording on pre-established data collection forms. after smoking, a few fish were randomly selected from each batch, wrapped in aluminum foil, coded and taken to the laboratory for the determination of chemical compounds (water content, protein, ash, mineral salts). determination of wood and smoked fish quality parameters quantitative field assessment include used wood volume, biomass and carbon emissions rate per sterre (1m 3 ) of wood through standard forest inventory and mensuration techniques (husch et al., 2003; ajonina, 2008) using the formulae: volume/sterre, v = va/vc = ∑ ½l (at+ab)/l× l× h (1) m = ρ×v (2) mc = ½ m (3) mco2 = mc × 3,67 (4) and the determination of energy efficiency (ef) of each type of oven using the method explained by feka (2009): ef= (mcfish weight fraction×wfish fresh weight×efish)/wwood ×cal wood (5) where in all cases: va = actual wood volume in m 3 ; vc = cubic volume of stark of wood including air spaces in m 3 ; l = wood sterre length in cm; i = wood sterre width in cm; h = wood height in cm; a(t, b) = surface area at the ends (top and bottom) of a log of wood in as sterre, ∑= sum of the logs of wood in the sterre, m = wood sterre biomass in kg; ρ = wood density: rhizophora = 0,89 (fearmside, 1997), 0,66 (djomo et al., 2011) in land forest woods; mc = carbon mass in carbon in kg; m = wood biomass; mc = carbon mass in kg; mco2 = quantity of carbon dioxide emission; ef energy efficiency; mcfish weight fraction = loss in weight of fish due to smoking in kg; wfish fresh weight = fish fresh weight in kg; efish = energy necessary to raise water in fish (5800kj/kg); and wwood = wood weight in kg; calwood = wood calorific value r racemosa = 16,9mj/kg, in land tropical forest wood = 4770 cal/g (doat 1977). laboratory determination of proximate chemical (composition) quantitative smoked quality parameters this included protein and ash content and salt mineral (ca, iron, mg, zn) content in ash using standard methods (aoac, 1980; afnor, 1981). organoleptic parameters of ordinal-scale scored qualitative quality appreciation assessments of smoked fish by fish smoking women include ordor (typical smoked fish ordor), color (black, marron, golden brown, brownish), taste (bad, good, very good) and texture (humid, hard). statistical data analysis both descriptive (tables, graphs, etc.) and inferential statistical analysis (hypothesis tests) especially analysis of variance (anova) procedure including sign tests were used to analyze the qualitative and quantitative data (quinn & keough, 2002). www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 9 published by scholink inc. 3. results socioeconomic characteristics of participants of all the women that participated most (more than 50% ) were aged 35+; more than 60% from secondary school and with more than 35% having 5-10 years’ experience in the activity in the area and were mostly nigerians (figure 4 ). figure 4. socioeconomic characteristics of fish smoking women in the village study communities www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 10 published by scholink inc. comparing quantitative parameters of wood and smoke oven types table 2. comparison of characteristics of types of ovens and wood species sources parameter wood species oven type mean sd cv (%) df f volume used (m 3 ) albizia glaberrina traditional oven 0.15 0.11 75.38 2 0.9ns improved oven 0.09 0.02 18.34 sacoglottis gabonensis traditional oven 0.14 0.13 89.17 improved oven 0.05 0.04 82.68 mangrove wood traditional oven 0.18 0.09 50.96 improved oven 0.16 0.00 0.00 co2 (t/stere) albizia glaberrina traditional oven 0.18 0.14 75.38 2 5.8** improved oven 0.11 0.02 18.34 sacoglottis gabonensis traditional oven 0.17 0.15 89.17 improved oven 0.06 0.05 82.68 mangrove wood traditional oven 0.25 0.15 57.49 improved oven 0.96 0.95 98.74 efficiency albizia glaberrina traditional oven 0.39 0.22 56.50 2 5.6** improved oven 0.46 0.11 23.57 sacoglottis gabonensis traditional oven 0.33 0.27 81.53 improved oven 1.27 0.56 44.27 mangrove wood traditional oven 0.00 0.00 58.12 improved oven 0.12 0.18 141.09 fish smoking time (hours) albizia glaberrina traditional oven 13.99 2.63 18.80 2 3.5* improved oven 14.65 1.09 7.45 sacoglottis gabonensis traditional oven 17.49 2.95 20.11 improved oven 14.67 2.38 13.58 mangrove wood traditional oven 20.84 4.72 22.66 improved oven 15.42 0.00 0.00 note. ** significant (p<0.01), * significant (p<0.05), ns not significant (p>0.05). generally, women processors spend more time (17.08±4.65 hours) and consume more wood 0.14±0.1m 3 using the traditional smokehouse. this excessive use of wood promotes the release of more co2 into nature. the comparative capacity characteristics of the traditional and improved smokehouses as summarized in table 2 showed that the volume of wood used with the system of improved smokehouse was less elevated with an average of 0,09±0,02 m 3 for “essack” 0,05±0,04m3 for “bidou” and 0,16±0,09 m 3 for mangrove wood; against an average of 0,15±0,11 m 3 , 0,14±0,13 m 3 and 0,18 m 3 www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 11 published by scholink inc. respectively for the same wood species in the traditional smokehouse. the mass of co2 released depended on the amount of wood used and the type of smoker. from this table, it appears that the high co2 masses released were from traditional oven explained by the large openings of this type of smokehouse, which causes a high loss of smoke and heat. there was a significant difference between the smoking time in the traditional and improved systems with an average of 15.05±1.09 (hours) with “essack” and 17.49±2.38 (hours) with “bidou”. on the other hand, the smoking time with mangrove wood in the traditional smokehouse 20.08±4.7 (hours) was higher than that of the improved smokehouse 15.42±0.06 (hours) that burns slowly but steadily. this reduction in time could be due to the ability of mangrove wood to burn even under humid conditions. these differences in high times with the two types of in land tropical forest wood could be explained by the moisture content of the wood, as the lack of aeration in the improved oven prevents air from maintaining the flame important to ensure that the combustion chamber is well ventilated so that the flame is always kept burning. qualitative assessments by organoleptic characteristics in general the organoleptic characteristics of smell, texture and taste of the fish smoked were significantly different with the different types of ovens but not with different species of wood except the color obtained with the two species of forest wood (essack & bidou) which were identical (black and marron), but those obtained with the mangrove wood brownish and golden brown. in general, by order of coloration of smoked fish preference, is the brownish and golden brown colors. there is no significant difference in the color and taste of fish obtained from traditional and modern oven, but there is a very significant difference (p = < 0.01) in the texture. this significant difference would be explained by the difficulty to reduce the burning fire contained in the combustion chamber of the traditional oven with the consequence of a hyper dehydration in the product; on the other hand, the improved ovens would maintain a regular pyrolysis during the whole smoking process, leading to a uniform reduction of the water contained in the fish flesh. the different species of wood used in this study have no influence on the final product organoleptic characteristics except coloration appreciation. this could be due to the fact that the two species of in land tropical forest wood would contain almost the same compounds as the mangrove wood. proximate chemical composition of smoked fish proximate chemical composition of smoked fish using wood and smoked oven types are showed in table 3. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 12 published by scholink inc. table 3. chemical composition of smoked fish per type of oven and wood source used parameter fish species smoke oven wood mean sd cv(%) df f moisture content (%) ethmalosa fimbriata traditional oven albizia glaberrina 19.22 12.13 63.1 2 5.48* sacoglottis gabonensis 23.53 7.77 33.0 mangrove wood 17.53 2.71 15.5 improved oven albizia glaberrina 33.88 12.29 36.3 sacoglottis gabonensis 22.57 4.62 20.5 mangrove wood 28.55 . pseudotolithus elongatus traditional oven sacoglottis gabonensis 21.68 . mangrove wood 9.78 . improved oven sacoglottis gabonensis 17.95 . mangrove wood 31.28 . proteine (%) ethmalosa fimbriata traditional oven albizia glaberrina 71.17 6.84 9.6 2 5.12* sacoglottis gabonensis 70.28 9.25 13.2 mangrove wood 70.52 4.00 5.7 improved oven albizia glaberrina 62.02 10.25 16.5 sacoglottis gabonensis 66.30 3.60 5.4 mangrove wood 67.71 . pseudotolithus elongatus traditional oven sacoglottis gabonensis 75.54 . mangrove wood 74.46 . improved oven sacoglottis gabonensis 72.65 . mangrove wood 66.26 . ash content (%) ethmalosa fimbriata traditional oven albizia glaberrina 5.61 0.16 2.9 2 0.44ns sacoglottis gabonensis 7.04 1.95 27.7 mangrove wood 6.02 0.36 6.0 improved oven albizia glaberrina 6.00 1.01 16.8 sacoglottis gabonensis 5.50 0.71 12.8 mangrove wood 5.71 . pseudotolithus elongatus traditional oven sacoglottis gabonensis 5.55 . mangrove wood 5.60 . improved oven sacoglottis gabonensis 5.37 . mangrove wood 7.31 . calcium(mg/ kg) ethmalosa fimbriata traditional oven albizia glaberrina 4500 2517 55.9 2 4.56ns sacoglottis gabonensis 1750 1100 62.9 mangrove wood 2100 2206 105.1 www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 13 published by scholink inc. improved oven albizia glaberrina 1175 171 14.5 sacoglottis gabonensis 1100 383 34.8 mangrove wood 1600 . pseudotolithus elongatus traditional oven albizia glaberrina 900 . sacoglottis gabonensis 1400 . improved oven albizia glaberrina 1100 . sacoglottis gabonensis 880 . note. ** significant (p<0.01), * significant (p<0.05), ns not significant (p>0.05). water content. there is a significant difference between the water content of the fish smoked in the chorkor ovens, where the averages obtained are between 22.57 and 33.88% for ethmalosa fimbriata and between 17 and 31% for pseudotolithus elongatus, while they are between 17.53% and 23.53% for ethmalosa fimbriata and between 9.77 and 21.68% for pseudotolithus elongatus in the traditional ovens. this translates into a hyper dehydration of the fish smoked in the traditional ovens leading to more or less friable products, thus making it very difficult to transport them, unlike those smoked in the chorkor ovens. protein content. there was a statistically significant difference between the protein contents. those obtained in the chorkor ovens are more reduced (with an average of 65.52% for ethmalosa fimbriata and 69.45% for pseudotolithus elongatus) compared to those obtained with fish smoked in traditional ovens presenting an average of 70.65% for ethmalosa fimbriata and 75.00% for pseudotolithus elongatus. the variations observed, particularly in the traditional smokehouses, can be explained by a concentration of proteins caused by a decrease in the water content of the product, which is more accentuated. during these operations there is an evaporation of water under the effect of heat the variations coming from the slight denaturation that occur during smoking. ash content. there was no significant difference between the averages obtained average between 5.6 and 7.04 for ethmalosa fimbriata and between 5.54 and 5.6 for pseudotholithus elongatus with the traditional smokehouses against an average between 5.4 and 5.99 for ethmalosa fimbriata and between 5.31 and 5.36 for pseudotholithus elongatus with the chorkor smokehouses. calcium content. there was statistically significant difference with higher calcium content in the traditional smokehouses (with an average of 2783mg/kg ethmalosa fimbriata and 1150 mg/kg pseudotolithus elongatus) than in the improved smokehouses (with an average of 1291.66mg/kg ethmalosa fimbriata and 990 mg/kg pseudotolithus elongatus). the high amounts of calcium with traditional smokehouses would be explained by a hyper dehydration of the smoked fish, making it difficult to separate the flesh from the bones during its determination in laboratory. fish bones are an important source of calcium, which is essential for the formation, growth and rigidity of bones, the development of teeth, muscle contraction, nervous irritability, blood coagulation and cardiac activity. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 14 published by scholink inc. iron content. there was no statistically significant difference between the amount of iron obtained (average between 0.68 and 8.17 mg/kg for ethmalosa fimbriata and 24.95 and 31.93 mg/kg for pseudotolithus elongatus) for the products from the traditional smokehouses and an average between 0.25 and 2.79 mg/kg for ethmalosa fimbriata and 33.68 and 50.14 mg/kg for pseudotolithus elongatus for the products from the improved smokehouse. these different values observed with the different species could be due to the diet of each species, their concentration in the natural environment. iron is necessary for the formation of hemoglobin, pigment of red blood cells ensuring the transport of oxygen, in the growth of the fetus and the child. however, we must note that the needs vary according to physical activity and age. iron needs are higher during growth, in athletes (loss of iron through sweat), in women during pregnancy, lactation and during menstruation. magnesium content. there was no statistically significant difference between the amount of magnesium obtained (average between 911.2 and 1826 mg/kg for ethmalosa fimbriata and 668 and 972 mg/kg for pseudotolithus elongatus) for the products from the traditional smokehouses and an average between 729.25 and 1458 mg/kg for ethmalosa fimbriata and 923 and 103 mg/kg for pseudotolithus elongatus (products from the improved smokehouse). indeed, magnesium plays an important role in the normal functioning of cells, in the transmission of nerve impulses, and in the regulation of the heart rhythm. it stimulates the formation of antibodies, and is necessary in many systems, especially related to energy production. correlation of amongst parameters figure 5 further shows the matrix of correlation between parameters as earlier explained. moisture content with time, ash with color, calcium with magnesium, calcium with wood volume, magnesium with wood volume, time with color, wood volume with efficiency, mass of co2 with efficiency, efficiency with texture and color with taste. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 15 published by scholink inc. versus moisture content (%) protein (%) ash content (%) calcium (mg/kg) iron (mg/kg) magnesum (mg/kg) time (hrs) wood volume used/sterre (m3) co2 emmitted (t/sterre) effciency colour texture taste moisture content (%) 1 -0.814** 0.109 -0.205 -0.169 -0.100 -0.489* -0.242 -0.004 0.132 -0.149 -0.233 -0.240 proteine (%) 1 0.026 0.205 0.238 0.160 0.322 0.230 0.062 -0.246 0.184 0.325 0.271 ash (%) 1 -0.088 -0.076 -0.130 0.112 0.236 0.040 -0.213 0.448* 0.085 0.297 calcium(mg/kg) 1 -0.289 0.917** -0.063 0.518** 0.146 -0.232 -0.055 0.081 0.139 iron (mg/kg) 1 -0.188 -0.028 0.032 -0.068 -0.258 0.094 -0.040 0.176 magnesimu(mg/kg) 1 -0.178 0.630** 0.328 -0.278 -0.104 0.065 0.075 time (hrs ) 1 0.198 0.073 -0.004 0.528** 0.013 0.388 wood volume used/sterre (m 3 ) 1 0.497* -0.603** 0.024 0.341 0.160 mass of co2(t/sterre) 1 -0.413* 0.228 0.260 0.135 effciency 1 -0.057 -0.495* -0.021 colour 1 -0.273 0.666** texture 1 -0.215 taste 1 figure 5. correlation matrix of parameters used note. ** significant (p<0.01), * significant (p<0.05), not significant (p>0.05) without asterisk. 4. discussion some smoked fish quality parameters may be comparable to some available studies carried out. the high smoking time in traditional wood smoking is comparable to the results of feka et al. (2009) who obtained an average of 21 hours. according to ndoye (2000), the maximum formal moisture content that can be tolerated is 30%: the product must then have a normally compact and non-friable flesh texture. the low water content obtained in traditional smokehouses (average between 17.53% and 23.53%) for ethmalosa fimbriata and between 9.77 and 21.68% for pseudotolithus elongatus is comparable to that found by nerquaye-tetteh et al. (2002) after smoking chrysichthys auratus with different types of wood (average between 9 and 13%). these results could be explained by a strong aeration of the firebox leading to a complete combustion and thus to an intense fire. smoked products and especially fish are highly valued and remain an essential source of dietary protein (patterson, 2005). the reduced protein contents obtained are close to those found by essumank (1992) on smoked tilapia (67.5%). these products smoked on different smokehouses with different wood species would be a very good source of animal protein. these quantities of iron obtained are close to those found by mujinga et al. (2009) on smoked oreochromis niloticus (2.613mg /kg) implications for efficient management and conservation of wood energy (dendro-bioenergy) adaptable to oven types while improving the quality of end product traditional oven uses more time, wood and lets out more co2 to obtain final product. improved oven uses less time a small amount of wood and releases little co2. in general, the equipment used for traditional fish smoking is varied, but traditional smokehouses are the most dominant. their www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 16 published by scholink inc. configuration and use are not optimized. these smokehouses do not have a specific bottom, they are open on all sides, which makes heat transfer difficult. this has an impact on the quality of the final product and on the energy efficiency. an improvement of the final product and the efficient management of lost energy would be to size the smokehouses, to close all the openings so as to leave only the one where the wood will be introduced in order to reduce the energy dissipation. proper handling of the smokehouse can also improve both the quality of the smoked products and the energy yield by diversifying the energy sources (charcoal, sawdust); the conservation of charcoal obtained after several smoking operations could be used in another smoking operation and this at the beginning of the operation. this is to extract water from fish without smoke, flame and at moderate temperature until the desired weight loss. smoking itself can take advantage of the remaining heat, by adding chips or sawdust slightly damp. improvement of certain practices or operations in the smoking process such use mangrove nypa plam (nypa fructicans) fruits to slowing down heat can preserve quantities of certain species and may help reduce deforestation. smoking is a widespread technique in many african countries, of which about 80% of fish catches are smoked or dried in order to limit damage (nsoga et al., 2020, and tamgno et al., 2020). many projects have introduced and disseminated various ovens generated by research since 1984 (levesque, 1992; mbengue, 1992; deme, 1998; deme, 2003; feka et al., 2009) the results showing a maximium adoption rate of 22% in chokor with investments with little internal rate of return but sundry brigged ovens with maximum adoption rate of 37% generated an internal rate of return of 18% and a net present value of 21 million of fcfa (42000 us dollars) (dame, 2003). in burkina fasso for example, kabré et al. (2003) observed by comparing three types of fish smoke ovens (dafing and monoclaire using traditional materials and chokor modern oven) that the quality of smoked fish depended on the type of oven with the chokor type giving more dehydrated smoked fish (72% moisture loss) than the traditional ones (dafin, 65% and monoclaire, 41%) but dafing and monoclaire were preferred for ease of availability of local materials and minimum amount of wood used from the nearby savanna dry forest. 5. conclusion comparison of traditional and improved smokehouses using different types of wood show that: the volume of in land tropical forest species sacoglottis gabonensis “bidou”, albizia glaberrina “essack”, and that of mangrove rhizopora spp “matanda” wood used in the improved smokehouse is significantly lower than the volumes used in the traditional smokehouses. smoking with the two species of forest wood in the improved smokehouses took lesser time than in the traditional smokehouse. on the other hand, smoking with mangrove wood in the traditional smokehouse took longer than in the improved smokehouse. ethmalosa fimbriata and pseudotolithus elongatus smoked in www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 17 published by scholink inc. the traditional and improved smokehouses with the different species of wood used were of good quality from the point of view of protein, mineral salts and organoleptic. water content obtained from the fish smoked with the traditional oven was reduced compared to the improved oven, which would make their transport and distribution difficult. the use of the two species of forest wood, sacoglottis gabonensis, albizia glaberrina provides the same product as with rhizophora racemosa, the improved smoker provides a product of better quality from the point of view of water content than the traditional oven and also releases less co2. acknowledgements the authors express their gratitude to the services of conservation of douala-edea, the government department for fisheries mouanko and the district head, traditional authorities and people of the study villages for their participation in the study. funding was from netherlands development organization novib to cameroon wildlife conservation society (cwcs). cwcs obtained the authorization from the ministry of wildlife and forests (minfof) to work in the area. references afnor (association française de normalisation). (1981). recueil des normes françaises des corps gras. graines oleagineuses (produits dérivés, 2rd ed., p. 438). ajonina, g. j. g., kairo, g., grimsditch, t., sembres, g., chuyong, d. e., mibog, a. n., & fitzgerald, c. (2014). carbon pools and multiple benefits of mangroves in central africa: assessment for redd+ (p. 72). retrieved from https://www.unep.org/pdf/reddcarbon_lowres.pdf ajonina, g. n. (2008). inventory and modeling mangrove forest stand dynamics following different levels of wood exploitation pressures in the douala-edea atlantic coast of cameroon, central africa. mitteilungen der abteilungen für forstliche biometrie, albert-ludwigs-universität freiburg, 2008(2), 215. retrieved from http://www.freidok.uni-freiburg.de/volltexte/6132/pdf/gordon_n._ajonina_thesis.pdf ajonina, g. n. (2022). cameroon mangroves: current status, uses, challenges, and management perspectives. in s. c. das, & e. c. pullaiah, ashton (eds.), mangroves: biodiversity, livelihoods and conservation. springer, singapore. https://doi.org/10.1007/978-981-19-0519-3_21 ajonina, g. n., & eyabi, g. d. (2002). saving cameroon’s mangroves through improved fish smoking houses: cameroon wildlife conservation society’s community-based approaches in douala-edea mangroves. in paper submitted to mangrove action project, los angeles, usa (p. 11). https://doi.org/10.1007/978-981-19-0519-3_21 www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 18 published by scholink inc. ajonina, g., timba, m., & njie. f. 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(1980). official methods of analysis (13th ed., p. 978). willian horwitz edr, washington. cdm-onfi-cwcs. (2009). protecting cameroon estuary mangrove though improved smoke ovens—project designing document clean development mechanism (p. 62). cwcs. (2001). cameroon wildlife conservation society douala-edea forest project: report of activities, mounko, cameroon (p. 32). deme, m. (1998). projet d’analyse du système de valorisation (transformation et commercialisation) des produits de la pêche artisanale dans les etats membres de la commission sous-régionale des pêches (csrp). in document de la csrp, août 1998 (p. 17). deme, m. (2003). évaluation economique de l’impact de l’adoption des fours chorkor et des fours parpaing dans la transformation artisanale du poisson a joal au senegal. djomo, a. n., knohl, a., & gravenhorst, g. (2011). estimations of total ecosystem carbon pools distribution and carbon biomass current annual increment of a moist tropical forest. journal: forest ecology and management, 261, 1448-1459. https://doi.org/10.1016/j.foreco.2011.01.031 doat, j. (1977). le pouvoir calorifique des bois tropicaux. revue bois et forêts tropiques (no. 172 mars-avril, 1977). essuman, k. m. (1992). le poisson fermenté en afrique: traitement, commercialisation et consommation fao (p. 80). eyabi eyabi, g. d. (2010). fish smoking training manual for stakeholders (p. 12). institute of agricultural research for development, irad, batoke-limbe specialized station for fisheries research and oceanography. fao. (2004). annuaire stastistique de la fao (vol. 11, p. 346). feamside, p. m. (1997). wood density for estimating forest biomass in brazilian, amazonia. for ecol manage, 90, 59-87. https://doi.org/10.1016/s0378-1127(96)03840-6 https://doi.org/10.1080/13504500509469627 https://doi.org/10.1016/j.foreco.2011.01.031 https://doi.org/10.1016/s0378-1127(96)03840-6 www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 19 published by scholink inc. feka, n. z., chuyong, g. b., & ajonina, g. n. (2009). sustainable utilization of mangroves using improved fish smoking systems: a management perspective from the douala-edea wildlife reserve, cameroon. tropical conservation science, 2(4), 450-468. https://doi.org/10.1177/194008290900200406 forkam, d. c., ajonina, g. n., ajonina, p. u., & tchamba, m. n. (2020). framework for assessing the level of stakeholders’ involvement and governance in mangrove management: case of selected local communities in the south west coastal atlantic region, cameroon. journal of ecology and the natural environment, 12(4), 150-164. https://doi.org/10.5897/jene2020.0830 fretey, j. (2021). good news from cameroon: the first marine national park. african sea turtle newsletter (no. 17). husch, b., beers, t. w., & keuhaw jr., j. a. (2003). forest mensuration (4th ed., p. 443). john wiley & sons. kabré, a. t., diarra, d., & traoré, a. (2003). le fumage du poisson au burkina faso: comparaison des caractéristiques et de la rentabilité de trois types de fumoirs améliorés. cahiers agricultures, 12(6), 409-417. knockaert, c. (1990). le fumage du poisson (p. 174). edition ifremer, centre de brest. levesque, p. (1992). expérimentation de nouvelles techniques (four chorkor) et améliorations de techniques existantes (pour parpaing et au sol). dtp no 8/atepas (p. 57). mbengue, m. (1992). synthèse des expériences d’introduction des fumoirs chorkor et parpaing réalisées au sénégal. r.p./atepas (no. 22, p. 47). minagri. (2002). document de stratégie du secteur rural au cameroun. ministère de l’agriculture, yaoundé (p. 212). mujinga, w., mutala, s., & hüsken, s. m. c. (2009). rapport d’analyse et table de valeur bromatologique de catégorie des poissons trouvés sur les marchés de poisson à lubumbashi, république démocratique du congo. ndoye, f. (2000). aperçu de la filière halieutique au sénégal. doc.gret, enda graf, cnearc (p. 21). retrieved from https://www.infoconseil.sn/ressources.html nsoga, j. v. f., milong, m. c. s., nchoutpouen, n. m., manz, k. j. c., ekwalla, m. n. r. j., tuem, s. r., ... ndomou, m. (2021). characterization of smoking activity and perception of smoked fish by households in the city of douala (cameroon). international journal of nutrition and food sciences 2021, 10(6), 159-166. https://doi.org/10.11648/j.ijnfs.20211006.16 patterson, j. (2005). le fumage: une technique idéale pour preserver la chair de mollusques. canning of smoked brown mussel. perna indica. phuket marine biological center special publication, 25(1), 219-220. quinn, g. p., & keough, m. (2002). experimental design and data analysis for biologists (p. 527). cambridge. https://doi.org/10.1017/cbo9780511806384 https://doi.org/10.1177/194008290900200406 https://doi.org/10.5897/jene2020.0830 https://doi.org/10.11648/j.ijnfs.20211006.16 https://doi.org/10.1017/cbo9780511806384 www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 1, 2023 20 published by scholink inc. tamgno, b. r., vatsou, j., zidiko, g., goudoum, a., & tinkeu, n. l. s. (2021). protection des stocks de poissons secs en afrique sub-saharienne. rev. mar. sci. agron. vét., 9(4), 755-766. microsoft word ees-v1n1-p18.doc energy and earth science vol. 1, no. 1, 2018 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 18 original paper cross-boundary energy-resources assessment for an integrated sources harnessing and sustainable development vinícius oliveira da silva1, miguel edgar morales udaeta1, andré luiz veiga gimenes2, jose aquiles baesso grimoni2 1 gepea/epusp energy group of the department of energy and electrical automation engineering of the polytechnic school of university of sao paulo, brazil 2 pea-department of energy and electrical automation engineering of the polytechnic school of university of sao paulo, brazil received: september 1, 2018 accepted: october 8, 2018 online published: november 1, 2018 doi:10.22158/ees.v1n1p18 url: http://dx.doi.org/10.22158/ees.v1n1p18 abstract the objective of this study is to evaluate the energy resources (er) and the regulatory framework of the south american countries aiming at the sustainable development and to develop the south america energy integration (saei) in the long term focusing on structures such as transmission lines and pipelines. the methodology is based on the ierp (integrated energy-resources planning) and the analysis of the ei existing in south america. as result, the regulatory assessment provided evidence that the current structure is already in place with binational hydroelectric plants and transnational pipelines that promote energy integration. on the other hand, saie still needs an institutional evolution that gives more integration and quicker solutions to international arbitration. finally, the construction of the attributes and sub-attributes and their respective valuations aiming at a saei strategy is not trivial, there is a need for the complete assessment of all the attributes and sub-attributes of the four dimensions established in the ierp methodology of the expansion of the ssers analyzed to provide a strategy for the saei. keywords energy planning, integrated energy resources planning (irp), energy integration (ie), south america 1. introduction despite the economic integration process—and energy—have started in europe, related discussions have spread throughout the world, leading initiatives in other continents, including in south america (sa) (reis, 2014). from the second half of the twentieth century were mechanisms developed in the www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 19 published by scholink inc. area of economic integration, the creation of the union of south american nations (unasul), the southern common market (mercosul) and andean community of nations (can), plus others bilateral and multilateral initiatives aimed to the use of shared energy resources (es) or trade them (reis, 2014; udaeta, da silva, galvão & de souza, 2016; de abreu, 2015). in the last century it has been noticed an important increase of the energy projects on the sa, hugely associated with the initiative for the integration of regional infrastructure in south america (iirsa) resulting in economic growth in the region, which in turn impacted on the increase of energy demand (udaeta, da silva, galvão, & de souza, 2016). indeed, studies of the the world energy council (wec) (wec, 2004) and international energy agency (iea) (iea, 2010), proved that the energy demand (enerdata, 2012) of developing countries have increased due to the considerable growth of their economies (imf, 2012), so much so that the title of the human development report 2013 drawn up by united nations development program (undp) was the rise of the south: human progress in a diverse world (undp, 2013). this report calls for new institutions which can facilitate regional integration and south–south cooperation and they are already sources of innovative social and economic policies, and increasingly development cooperation partners for other developing countries. the development of the countries involves the access to energy resources and in turn this is linked to long-term energy planning. since they are disproportionately distributed around the world, access to them is the question of disputes filed by various interests, being a matter of great geopolitical importance to a state. the access to es involves different varieties of interests between countries that can be conflicting. thus, a reasonable alternative, it is considered that policies aimed at energy integration (ei) can meet interests involved (reis, 2014; udaeta, da silva, galvão, & de souza, 2016). the essential idea of the ei is noted the contribution that energy and economic sectors in each country can the economic and social development process, within the framework of regional integration (undp, 2013; udaeta, burani, fagá & oliva, 2006). ei between regions and countries is fundamental to allow access to these sources, either through the direct transport of fossil fuels or biomass, through the sharing of hydroelectric power plants in border rivers or, indirectly, through the construction of transmission lines that power from the generation point to other consumer markets. by enabling the commercialization of ers or electricity itself, based on bilateral or multilateral agreements, ei can provide a reliable and efficient supply to huge energy consumers, also bringing economic gains for countries that sell their ers and its surplus electricity (suárez, 2006; calogeras, silva, grimoni, & udaeta, 2016). in the long term, is optimized energy generation, while taking advantage of the diversity resulting from connection to es from neighboring countries, eliminating the dependence on a single energy source and reducing supply costs. also, the creation of economic blocs and energy strengthens the integrated region, leveraging the political, commercial, social and cultural relations between its members (reis, 2014; calogeras, silva, grimoni, & udaeta, 2016). additionally, despite the potential benefits related to cross-border ei, there are many elements that hinder their achievement, they order being technical, environmental, political and economic. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 20 published by scholink inc. in this sense, the objective of the paper is to evaluate the ess and the regulatory framework of the south american countries aiming at the sustainable development and to develop the regional energy integration in the long term focusing on structures such as transmission lines and pipelines. therefore, the work is divided in four more items, the first one being the analysis of the energy integration existing in south america (supranational organisms and infrastructures), followed by the description of the methodology of evaluation of the first and second-degree ess that allow the energy integration in the long run and, finally, the results and analyzes of the study and its final considerations are presented. 2. energy integration in south america the main difficulties, associated with the implementation of integration projects, refers to the articulation of rules and congruent with the incentive to investment and energy interdependence policies. it comprises several aims, agreements and regulations that involve complex legal issues facing opening markets and thereby enabling the creation of rules to facilitate equity transactions and investments, whether them are state, private, national or multinational. this process involves internal political issues of the countries related to the acceptance and approval of laws and internal projects involving diverse interests within the nation, in addition to elements associated with the foreign policy of each state and its geopolitical interests in the region (reis, 2014; udaeta, da silva, galvão, & de souza, 2016; de abreu, 2015). about differences of interests among sa countries case, one can use the question as an example of the suspension of the supply of natural gas through the cross-border gas pipelines from argentina to chile, this suspicion occurred even though there were contracts signed between the companies of both countries and the interruption of ute uruguaiana (639 mw) from 2009 to 2014 due to lack of gas in argentina (faria, silva, udaeta, abreu, gimenes, & grimoni, 2016) or also the bolivian gas, in which bolivia nationalized refineries belonging to petrobras, claiming that the contracts had been established the wounded interests of the bolivian nation (antunes, 2007). these cases demonstrate that the larger the number of agents involved in the process, the greater the effort in establishing policies of interest to everyone. that is why the most fruitful experiments were those made them bilaterally arising from projects with strong participation of national states. from a technical standpoint, the interconnections require an infrastructure with bi-reaching or multi goals, that includes all involved and interested. so that the integration process is done in a cohesive manner, it is essential to studies that provide adequate planning be made, about the energy generation, transmission and distribution (g-t-d), as well as the interests and economic returns for the various agents involved in the issue. the greater the need for infrastructure and technical complexity related to the projects become more expensive the same—which implies the need for large investments of money and, most often, in various financing. in the case of sa, the infrastructure integration projects to sizable proportions by both distances, as the natural difficulties imposed by the environment. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 21 published by scholink inc. 2.1 history of the south american energy integration process the process of south american energy integration (saei) starts from the mid-twentieth century, by means of natural gas, having two axes of the main action, oriented from the actions of the mercosul and can (udaeta, da silva, galvão, & de souza, 2016; antunes, 2007). it should be noted that these economic blocks have economic complementation agreements among themselves and with chile, that is not a member of both. the process of eiarisen in the xx-xxi century and it can be separated into three stages (reis, 2014): i. first period, the 1970-1980s, was marked by a great performance of national states in building binational projects, such as the hydroelectric power plants of itaipu (brazil/paraguay), salto grande (argentina-uruguay) and yacyretá (paraguay/argentina), and transmission lines associated with these binational power plants. ii. second period occurred after the end of the 1980s. it was marked by political economic liberal reforms, resulting in decreased performance of states and the increased of the private participation in the sa country's economy. thus, it has begun the implementation of projects with varying degrees of participation of public, private and mixed enterprises, involving mainly the gas and oil sector. many binational pipelines have been constructed, demonstrating the importance of this resource within the saei. even with the differences involving the form of state action. indeed, it is noticed that projects were limited to the bilateral framework, demonstrating the nonappearance of a regional integration policy. iii. third period, occurred in the xxi century, it is turned is linked to the economic and political changes on the sa. initially, with the election of presidents of the left parties made to gather strength in the region’s anti-imperialist and anti-liberal discourse, changing the financing projects logic and strengthening the participation of states in the economies again. meanwhile, economic growth achieved by countries of region, especially brazil, resulted in an increase in its energy demand. with this, the 1st decade of xxi century, there was a propensity to transform this idea bilaterally (first period) to give a more regional and multilateral character to integration projects. in this context that was shaped in 2000, the initiative for the integration of regional infrastructure in south america (iirsa), in order to promote the interconnection of telecommunications, energy, transmissions lines and gas & oil pipelines (udaeta, da silva, galvão, & de souza, 2016; oxilia, 2009). with the iirsa’s project and with financing from institutions such as the world bank (wb), inter-american development bank (idb), financial fund for the development of prata basin (fonplata) and the andean development corporation (caf), it was intended to establish conditions to the development of trade agreements and ei. thus was deposited confidence in the achievement of iirsa, despite the logical difficulties inherent to their achievement, such as disparity markets, privilege certain actors, history of binational conflicts and difficulty of regulatory consistency between countries (udaeta, burani, fagá, & oliva, 2006). in 2009, iirsa has been discontinued and its projects were www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 22 published by scholink inc. linked to the south american council of infrastructure and planning (cosiplan) linked to the unasul (cosiplan, 2013). also, the cosiplan along with unasul, retains the idea of strengthening multilateral relations in sa, to give greater political support infrastructure integration projects (udaeta, da silva, galvão, & de souza, 2016). 2.2 southern common market created in 1991, the mercosul consisting of brazil, argentina, paraguay, uruguay and venezuela (mercosul, 2016). despite the conception of this economic bloc has been linked to the need for expansion of internal markets and stimulate the circulation of goods and services in the region, without being tied directly to the energy issue, there were already binational relations among its members. since the formation of mercosul, the energy sector showed considerable changes. among them stand out the reform of the state roles, that acting more as a regulator than as an entrepreneur, and consolidation of natural gas (ng) as an integrating feature of the region. all countries in the region have construction pipelines (udaeta, burani, fagá, & oliva, 2006). among the binational projects of power generation worth mentioning the construction of salto grande, itaipu and yacyretá power plants, and the central salta, a combined cycle power station, built by a chilean company to generate electricity from argentina's gn, but not providing energy for this country. in the case of itaipu, aiming harness the hydroelectric potential of the paraná river, brazil was responsible for the investments and setup project the construction of the power plant. in addition, to financing the part that would fit paraguay (oxilia, 2009; oxília & fagá, 2006). 2.3 andean community of nations region created in final of 60’s, the can is formed by bolivia, colombia, ecuador and peru. the region covered by the can has a huge potential energy, both in terms of hydrocarbons (gas & oil), as regarding the hydro, among others. about the oil market, colombia, ecuador and venezuela are configured as suppliers to countries like brazil, chile and peru, since they have oil consumption that exceeds their production. in contrast, with bolivia and venezuela that have resources that exceed their local demands. it is important highlight the chile’s situation, that due to its lack of ess, is much interested in integration projects that allow the supply of its internal energy demand. castro (castro, dassie, & delgado, 2009) says that the process of ei in the can began in 1969 with the construction of the zulia-la fria transmission line, connecting colombia and venezuela. the authors claim that this project was the first step for the ei occurred in the region. besides that, it state that the evolution of the process of electrical interconnection between the andean countries has enabled advances, such as the prediction of building an interconnection between bolivia and siepac. udaeta et al. (udaeta, burani, fagá, & oliva, 2006) also highlight the role of interconnections in the integration process in can, noting that bolivia appears as a “hinge”, because of its possibilities of interconnection with brazil, chile, argentina and peru. besides the physical integration, it cannot overlook the advances that have happened in legal and political terms to permit the access to transmission lines between countries. thanks to that, better www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 23 published by scholink inc. prospects around integration projects in the region. even so, it is of great technical, economic, political and complexity to implementation of transnational projects. so that the more countries involved, and the larger the area covered, the greater the effort. antunes (antunes, 2007) cites the proposal for ei taken by chile in 2007, and that would involve this country along with ecuador, bolivia, colombia and peru, based on an can multilateral agreement aimed at prevent interference geopolitical discussions on exit to the sea for bolivia lost. 2.4 south america energy integration projects clearly, it cannot reduce the process saei only to economic blocs in the region. in this sense, the conception of iirsa, and after the cosiplan makes integration projects that go beyond the limits of economic blocs, giving greater geopolitical consistency to the region are fortified. the initiative has certain principles involving the approach between the countries that are based on open regionalism, contemplating the need to minimize internal barriers to commerce, bottlenecks in infrastructure and regulatory systems and operation, in the integration and development axis (ida), that is organized into 10 axes (andean, amazon, peru-brazil-bolivia, capricorn, guyanese shield, south andean, central interoceanic, mercosur-chile, parana-paraguay waterway and south) (udaeta, da silva, galvão, & de souza, 2016; oxilia, 2009) regions was taken, clearly transcending the boundaries of economic blocs. throughout its existence, iirsa and currently the cosiplan, developed important projects, with a portfolio of 579 projects in study (23.5%), pre-running (28.8%), running (29.2%) and completed (18.5%), with an approximate investment of us$ 163.069 billion (iirsa, 2016). according to the cosiplans projects portfolio (cosiplan, 2013), the energy sector concentrated 59 projects, of which 27 (46% of the total) are aimed at generating, representing 75% of the total investment, and 32 inter connections projects. these projects receive investment especially from public/private partnerships (68% of total investments) followed by the public sector (25%); this characteristic is due to the high value of the individual projects and the fact that they are structuring, with market opening bias, creating conditions for businesses and society to have access to new regions and can dispose their productions. projects in the energy sector are mainly based on the construction of new interconnections, 52.5% of the total projects and 25.1% of investments. hydroelectric plants, because they are characterized as large enterprises of electricity generation, hold 27.1% of the projects portfolio and 63.8% of investments. by analyzing these data, iirsa fostered a development that is organized much like physical interconnection than actual integration. this phenomenon is related to building a highway network connecting the atlantic and pacific interests, to foster the flow of goods across the sa (reis, 2014). gudynas (gudynas, 2008) inquiries the interests that were behind the iirsa project by privileging the physical interconnections and seek not intrinsic to strengthen other aspects integration process such as productive, political and cultural ties. other limitations are associated to iirsa the lack of progress in the sectorial policies harmonization, relevant regulations and tiny consideration given an environmental www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 24 published by scholink inc. and social aspects. about the pursuit of multilateralism in the saei process, it should be noted the role of bolivia, which has a role of coordination between of the southern cone and the can countries. being a country with huge ng reserves and it has low power consumption. bolivia is shaping up as a major supplier of ng resource to importing countries, such as argentina, brazil and chile. i.e., the bolivia-brazil pipeline, a major milestone of the saei, due the importance of consolidating ng chain in the brazilian energy matrix (reis, 2014). ei also consolidates brazil as a major buyer of energy. despite having huge reserves of ess, it has shown a significant increase in its demand. consequently, the brazilian government has increasingly sought to stimulate energy ventures outside its territory. in addition, to seek for satisfy its energy demand, there is a clear interest in encouraging the sharing of brazilian capital on projects through funding from its national bank, named national bank for economic and social development (bndes) and the participation of brazilian construction companies civil (udaeta, burani, fagá, & oliva, 2006). in this context, in 2009 brazil and peru was signed by both countries an agreement for the construction of six hydroelectric plants—inambari (2,000 mw), sumabeni (1,740 mw), paquitzapango (2000 mw), urubamba (940 mw), vizcatán (750 mw) and cuquipampa (800 mw) together these plants would total approximately 9,000 mw of installed capacity (eletrobás, 2013) to supply the energy to both countries and situated in the amazon basin of peru's territory. due to the position where it will be deployed, covering areas of huge biodiversity and where local communities, projects of this nature are carried live by controversy due to contradictions involving their economic gains and environmental impacts they generate. in fact, despite these initiatives have targeted to meet economic interests in the area, their environmental and social impacts are left in the background. 3. integrated energy resources planning (ierp) the energy planning often has as priorities the energy supply and gdp increase in the short term and, eventually, medium term. this traditional planning is concerned exclusively with the difference between the forecast energy demand and the prediction of supply. hence, the amount of energy needed in the short and medium term is determined and the options that present lower cost of installation, maintenance and operation are identified. thus, traditional energy planning foregrounds the technical and economic aspects at the expense of environmental and social aspects (eletrobás, 2013; udaeta, 1997; udaeta, 2012; grimoni, galvão, udaeta, & kanayma, 2015). as the integrated energy resources planning (ierp) meets the need for a more complete and comprehensive planning when compared to the traditional planning, its main function is to be a tool for energy planning in the short, medium and long term, in which various ess, viewpoints and aspects are considered (udaeta 1997). however, there are evidences that the energy sector adapts too slowly to this model of energy planning (grimoni, galvão, udaeta, & kanayma, 2015). besides that, the ierp differs from the traditional planning in one main aspect, i.e., the insertion of stakeholders in the planning www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 25 published by scholink inc. process, from the policy maker to the es user (udaeta, 2012). the ierp is the process through which a group of alternatives, both on demand and supply sides, are planned, implemented and evaluated based on at the costs that balance the groups interest (cicone, 2008). the goal constantly pursued by ierp is the determination of the portfolios of ess at the lowest full cost; and, the traditional ways of calculations fail to consider all the elements present in such analysis. besides, the pressure exerted by various members of the society can often causes a great project financial evaluation to be unviable, generating waste of time and money to those who believed and invested in energy project, since many measurement systems lacked strategy alignment, a balanced approach and systemic thinking, they had difficulty in systematically identifying the most appropriate metrics (eletrobás, 2013; udaeta, 2012; udaeta, galvão, rigolin, & bernal, 2016). in the ierp the participation of society is called engaged-stakeholders (en-st). this detailing and deep stratification of ess allow the decision maker to have grants that will help in selecting the next investment, i.e., impacts, benefits and risks are clearer than in many traditional planning (gimenes, 2004). linked to this, the fact that the ierp examines the energy planning in the long term, it assists entities in having several use scenarios for 20 and 30 years or more. also, in its full form, the ierp can provide organizations with a framework to visualize how these scenarios will be modified according to the short-term choices. in this sense, the ierp (cicone, 2008; gimenes, 2004; udaeta, gimenes, galvão, & fujii, 2004), i.e., ierp, places the sustainable development as its most diffuse goal. thus, to use sustainable energy in general and for ierp it is necessary to compare each one supply-side energy resources (sser) and each one demand-side energy resources (dser) in a way to generate the listing, screening and selection of ess for later create the ranking of ess, organized from the most indicated to the least indicated to be applied for instance, the ranking is only a reference for the next steps of ierp (gimenes, 2004). it is worth mentioning that one of the basic premises of the ierp is not to discard any es. a resource that is not available or is not of immediate interest can be included, for example, five or ten years ahead, as the ierp is a long-term energy planning, which should include scenarios that incorporate effects on the society (eletrobás, 2013; udaeta, 1997; grimoni, galvão, udaeta & kanayma, 2015; gimenes, 2004; baitelo, 2011). the list of ess aims to identify all resources that can be used throughout the planning horizon, regardless of technological characteristics or their acceptance, whether social or market. already the screening is simply the moment prior to selection and ranking, in which consideration for full assessment of some resources is suspended as determines methodologies and procedures within the ierp (udaeta, 1997; cicone, 2008; baitelo, 2011). about the supply-side energy resources (sser), it is worth defining them as the composition of a primary source of energy linked to a particular technology of use (cicone, 2008). already the demand-side energy resources (dser) are the technologies and/or actions that allow you to conserve or save energy. this energy, called “virtual generation”, is seen in the ierp as an es because it allows www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 26 published by scholink inc. its use in other end-uses or even saves the energy source for later use. nevertheless, it still postponing investments in the energy sector (cicone, 2008). usually, this decision making is performed with technical and economic data. however, in the case of ierp are included other dimensions which participate with the same weight in the results. among the technical-economic aspects are considered the environmental, social and political factors. it also evidence that the greatest difficulties of considering these types of impacts are subjectivity and difficulty in pricing (udaeta, galvão, rigolin, & bernal, 2016). 4. methodology elements the methodology adopted for the characterization of sser is based on the survey of the several existing technologies to produce energy through various sources, whether renewable or not, as well as their generators and their characteristics, and it is an adaptation based on the procedure described by rigolin (rigolin, 2013). the essential step to the methodology is the determination of the decision tree, which consists of attributes, sub-attributes, ess and its structure. from this tree, as stated in the irp established methodology (udaeta, 1997) the main dimensions cannot be modified, which are divided as follows: (i) technical-economical; (ii) environmental; (iii) social; and (iv) political, see figure , and each of them has equivalent weights of 25%. technical-economical environmental social politicaldimensions attributes sub-attributes figure 1. hierarchical tree model methodology for ahp (rigolin, 2013) the complete model for the ierp has about 50 attributes and sub-attributes (baitelo, 2011) distributed in four dimensions. it is worth mentioning that the sub-attributes are customizable according to the applied ierp and, for verification of the model. after the construction of the decision tree, the ess can be analyzed in accordance with all attributes and sub-attributes defined in the hierarchical tree (udaeta, galvão, rigolin, & bernal, 2016) . as evaluation is linked to long-term planning it is important to create scenarios of 20-30 years. the construction of this long-term planning horizon can have based on data such as gdp per capita, population growth, % of electricity coverage and basic sanitation, etc., it is possible to estimate the demand for electric energy, drinking water, sanitation and so on according to their usual growth. the total demand will be the sum of the repressed and usual demands in each case (gimenes, 2004). www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 27 published by scholink inc. this study demonstrates the valuation of the resource property attribute, which analyzes the origin and ownership of energy sources, considering their local, regional or national availability and the extension of the use of resources through international agreements and energy integration measures, and their respective three sub-attributes linked to the political dimension: (i) ownership, property and energy integration, see figure 2. political resource property propertyownership energy integration dimensions attributes sub-attributes figure 2. hierarchical tree model of attributes and sub-attributes studied in the political dimension the algorithms of valuation attributes of the possession and ownership of ess and energy integration between regions are constructed together. the type of unit evaluated are qualitative and the conversion to standardization of this type of unit is by means of discretization (rigolin, 2013), see table 1. the possession of the energy source can be evaluated as: (i) free access (such as wind, solar and biomass); (ii) intended for multiple uses (water); (iii) owned by the union or (iv) foreign (baitelo, 2011). the location of energy sources can be measured in surveys of local, national and international databases, property and ownership of ess can be researched in local and regional legal frameworks and energy integration agreements and commitments are constantly updated information by newspapers, journals or official publications of government agencies. table 1. data types contained in the political dimension (rigolin, 2013) attribute sub-attribute type of unit / unit conversion to standardization resource property ownership qualitative discretization property qualitative discretization energy integration qualitative discretization 5. energy potential of south america sa is a region rich in ess, especially oil and water resources, various integration projects in terms of www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 28 published by scholink inc. energy already deployed or are in process in sa is worth mentioning that many of these features occur so border making it complex to operate and manage, highlighting the andes and the amazon river (reis, 2014). andes is a large mountain range spanning five countries in sa, it is being a natural border, and constitutes a major mineral area in the world. the waters of the amazon river account for much of the freshwater available in the world. this river initiates in peru, crossing the border with colombia until you reach the tri-border involving these two countries and brazil. it is not by chance, these three countries are those with greater hydroelectric potential in sa, see figure. analyzing the figure, it is seen that the total hydropower potential of the sa is 590 gw, so that brazil is by far the country with the greatest potential, exceeding 250 gw. it is no wonder that this country has the largest hydropower generation in the region (403 twh in 2010), corresponding to 11.5% of the world's hydroelectric production (iea, 2017). likewise, it should be highlighted venezuela, since this country occupies the 9th place ranking producer of hydroelectricity in the world and is the second largest sa [(iea, 2017; oecd/iea, 2012). figure 3. south american hydroelectric potential (udaeta, da silva, galvão, & de souza, 2016; oecd/iea, 2012) about hydrocarbons should be highlighted reserves of ng and oil on the continent. sa has about 4.2% of global ng proved reserves, so that the majority is in venezuela with 6.4 gm³, followed by brazil and peru with 0.4 gm³ each one and, argentina and bolivia with 0.3 gm³ each (bp, 2018), see figurea. oil cannot be overlooked when it comes to meeting the sa energy potential. the region has large proven reserves of this resource, with almost 19% of the total proved reserves, highlighting, once again, to venezuelahas the largest proven oil reserves in the world with 303.2 billion barrels of oil (bp, 2018). brazil and ecuador also have significant reserves of 12.8 and 8.3 billion barrels of oil respectively,see figureb. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 29 published by scholink inc. 5% 4% 4% 5% 81% 1% brazil argentina bolivia peru venezuela others 4% 3% 92% 2% brazil ecuador venezuela others (a) (b) figure 4. south america distribution of proven reserves in 2017 (a) natural gas and (b) oil 6. construction of attributes and sub-attributes in south america energy integration the supply-side energy resources (sser) analyzed is natural gas (gn) linked to bolivia's proved reserves and transported in gasbol (brazil-bolivia gas pipeline) to brazil. this choice is due to the great availability of the energy source and the possibility of exports in the long term. following is the valuation of attributes and sub-attributes:  place of the energy source: it fits as a national source, in the case of bolivia;  ownership: is of the union according to the ley de hidrocarburos (ley n° 3058) that establishes that the state will exercise, through the yacimientos petrolíferos fiscales bolivianos (ypfb), its proprietary right over all hydrocarbons (bp, 2018);  property: state-owned and private companies established in five brazilian states, which use the resource through national and imported technologies (bp, 2018; tbg, 2016), being the end-use to multipurpose (electricity, heat and etc);  integração energética: long-term bilateral contract, 30 years, in the take-or-pay category, signed between the state companies of both countries, ypfb of bolivia and petrobras of brazil. being operated on the transportadora brasileira gasoduto bolívia-brasil sa (tbg) and on the bolivian side by gás transboliviano sa (gtb), both are subsidiaries of the state-owned companies of each country (tbg, 2016; udaeta & da silv, 2017). 7. elements for consideration likewise, ess are not spread evenly around the world, so that trade in ess and electricity can benefit both the importing and exporting country. despite the difficulties involving ei as questions of sovereignty of countries and divergence of interests among en-st, the process of ei can take a lot of benefits for developing countries. sa case shows that, in a context in which the process of economic integration is in a somewhat advanced stage, thus hampering ei. the transnational energy projects are restricted to bilaterally. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 30 published by scholink inc. showing that the process of saei was not an end, but a means to meet the energy and economic needs of certain countries and agents in sure recent historical periods. in other words, projects such as itaipu and bolivia-brazil ng pipeline had as main aim to serve the economic interests of the parties involved and not ei itself. even in recent initiatives, such as iirsa and now cosiplan, the ei sectors of the sa countries occurs in a larger plan. infrastructure’s integration, which also involves networks of movement and communication. therefore, it means achieving a bigger integration project. even so, cosiplan is the main initiative of saei in the beginning of the 21th century, in a context where projects occur beyond the traditional economic blocs. the construction of the attributes and sub-attributes and their respective valuations aiming at a south american energy integration (saei) strategy is not trivial, since there is an intense need for databases and information from each analyzed region, be it a national or supranational state, for later systematization and evaluation. finally, there is a need for the complete assessment of all the attributes and sub-attributes of the four dimensions established in the ierp methodology of the expansion of the ssers analyzed to provide a strategy for the saei. references antunes, j. c. (2007). infraestrutura na américa do sul: situação atual, necessidades e complementaridades possíveis com o brasil. baitelo, r. l. (2011). modelo de cômputo e valoração de potenciais completos de recursos energéticos para o planejamento integrado de recursos. escola politécnica da universidade de são paulo. bp. (2018). bp statistical review of world energy 2018. london. calogeras, h., silva, v. o., grimoni, j. a. b., & udaeta, m. e. m. (2016). energy productivity estimation in the economy of the common market of south america. 23rd world energy congress, 1, 869-883. castro, n. j., dassie, a. m., & delgado, d. (2009). indicadores mundiais do setor elétrico—as experiências latino-americanas de integração energética. rio de janeiro. cicone, d. (2008). modelagem e aplicação da avaliação de custos completos através do processo analítico hierárquico dentro do planejamento integrado de recursos (pp. 1-146). dissetação—esc. politécnica da univ. são paulo. https://doi.org/10.11606/d.3.2008.tde-08062009-164421 cosiplan. (2013). cartera de proyectos 2013. iv reunión ordinária de ministros del cosiplan. chile. de abreu, a. c. (2015). a integração da indústria de energia elétrica na américa do sul: análise dos modelos técnicos e de regulamentação. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 31 published by scholink inc. dos reis, a. g. (2014). a arquitetura da integração energética sul-americana, a participação brasileira e a geoenergia humana. eletrobás. (2013). http://www.eletrobras.com enerdata. (2012). http://www.enerdata.net faria, d. m. c., silva, v. o., udaeta, m. e. m., abreu, a. c., gimenes, a. l. v., & grimoni, j. a. b. (2016). power deal of canada & us assessment seeking a brazilian model for energy integration in south america. 23rd world energy congress, 607-625. gimenes, a. l. v. (2004). modelo de integração de recursos como instrumento para um planejamento energético sustentável. escola politécnica da universidade de são paulo. grimoni, j. a. b., galvão, l. c. r., udaeta, m. e. m., & kanayma, p. h. (2015). iniciação a conceitos de sistemas energéticos para o desenvolvimento limpo (2nd ed.). são paulo: edusp. gudynas, e. (2008). as instituições financeiras e a integração na américa do sul. in r. verdum (ed.), financiamento e megaprojetos. uma interpretação da dinâmica regional sul americana. brasilia: inesc. iea. (2010). world energy outlook 2010. paris. iea. (2017). key world energy statistics 2017. iirsa. (2016). iniciativa para a integração da infraestrutura regional sul-americana. retrieved from http://www.iirsa.org imf. (2012). international monetary fund. retrieved from http:// www.imf.org mercosul. (2016). mercado comum do sul. retrieved from http://www.mercosur.int oecd/iea. (2012). technology roadmap. hydropower. paris. oxilia, v. (2009). raízes socioeconômicas da integração energética na américa do sul: análise dos projetos itaipu binacional, gasbol e gasandes. oxília, v., & fagá, m. w. (2006). as motivações para a integração energética na américa do sul com base no gás natural. petro e química, 289, 70-74. rigolin, p. h. da c. (2013). desenvolvimento de um sistema para classificar recursos energéticos de oferta e demanda com base no cômputo e na valoração do potencial completo dos recursos energéticos dentro do planejamento integrado de recursos energéticos. escola politécnica da universidade de são paulo. https://doi.org/10.11606/t.3.2013.tde-09072014-111702 suárez, l. p. l. (2006). o papel das petrolíferas para o desenvolvimento da integração energética: a formação do mercado de gás natural na américa do sul. unicamp. tbg. (2016). shareholding composition. retrieved from http:// www.tbg.com udaeta, a. g., da silva, v. o., galvão, l. c. r., & de souza, f. n. (2016). analysis of energy integration and the transboundary superstructure in south america. j. bus. econ., 7(1), 21-43. udaeta, m. e. m. (1997). planejamento integrado de recursos energéticos—pir—para o setor elétrico (pensando o desenvolvimento sustentável). escola politécnica da universidade de são paulo. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 32 published by scholink inc. udaeta, m. e. m. (2012). novos intrumentos de planejamento energético e o desenvolvimento sustentável—planejamento integrado de recursos energéticos na usp. universidade de são paulo. udaeta, m. e. m., & da silva, v. o. (2017). pea5899 (p. 60). udaeta, m. e. m., burani, g. f., fagá, m. t. w., & oliva, c. r. r. (2006). ponderação analítica para da integração energética na américa do sul. rev. bras. energ., 12(12). udaeta, m. e. m., galvão, l. c. r., rigolin, p. h. da c., & bernal, j. l. de o. (2016). full assessment energy-sources for inclusive energy-resources planning. renew. sustain. energy rev., 66, 190-206. https://doi.org/10.1016/j.rser.2016.07.008 udaeta, m. e. m., gimenes, a. l. v., galvão, l. c. r., & fujii, r. j. (2004). elementos de planejamento integrado de recursos energéticos ( pp. 1463-1473). undp. (2013). human development report 2013—the rise of the south: human progress in a diverse world. united nations development programme (undp), new york. wec. (2004). eficiência energética: uma análise mundial. rio de janeiro. energy and earth science vol. 3, no. 2, 2020 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 19 original paper application of remote sensing in identifying and mapping of exposed rock massifs, potential quarry sites in yaounde-cameroon elvis kah 1* , amaya adama 1 & roland ndi 2 1 department of geological mapping and geomatics, school of geology and mining engineering, university of ngaoundere, meiganga, cameroon 2 department of geography, faculty of arts, letters and social sciences, university of yaounde i, yaounde, cameroon * elvis kah, department of geological mapping and geomatics, school of geology and mining engineering, university of ngaoundere, p. o box 115, meiganga, cameroon received: february 8, 2020 accepted: february 24, 2020 online published: july 27, 2020 doi:10.22158/ees.v3n2p19 url: http://dx.doi.org/10.22158/ees.v3n2p19 abstract since 2010, cameroon opted for an aggressive mineral exploration in order to attain the status of an emerging country by 2035. thus, any surface and sub-surface resources found important has to be valorised. this study therefore seeks to contribute towards the drive to an emerging nation initiative through the identification and mapping of exposed rock massifs in the city of yaounde using remote sensing techniques. the fieldwork constituted of locating the geographic coordinates of some rock outcrops with the gps, projecting the samples on the a geo-referenced satellite image using gis software (arcgis) and simulating the spectral behaviour of those spots to those of similar reflectance in order to conclude as the targets. this was then treated in gis software for proper mapping to be done. the study revealed that yaounde is actually endowed with enormous exposed rock massifs which can actually be valorised for construction works. some of the exposed rocks are surrounded by vegetation especially at the outskirts of the city, others are actually engulfed within built-up areas with difficult accessibility while others could only be exposed on excavated areas for construction. some are already under exploitation while others are not. some of the rock outcrops were spotted of shallow extensions while others are small in surface areas but project deep down the soil. these results are of importance for use by quarry companies and the government of cameroon through its ministry of mines for onward allocation of exploitation permits. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 20 published by scholink inc. keywords exposed rocks, quarry, remote sensing, spectral discrimination, yaounde 1. introduction aggregates resulting from the crushing of rocks constitute main construction materials throughout the world. these rocks sometimes remain intrusive or become extrusive by projecting to the surface that facilitate their identification for exploitation. some countries are endowed with these resources while others are not. to this effect accords are signed for the exchange of certain resources between countries. this is the case between cameroon and some south east asian countries for exportation of fresh water sand. such accords also exist between niger and some european countries for export of uranium. for the case of uranium, they are mostly exposed to the extent that there is no need for techniques to be deployed for their identification. their main use is to generate electricity rather than for construction. the rock outcrops that constitute the base of this study include gneiss, schist, amphibole, granite, quartzite and syenite. in parts of the adamawa, west and north west regions of cameroon, the outcrops of these rocks cover extensive surfaces without any exploitation. this is simply because of the cost of transportation to the construction sites. according to the mining code of cameroon, any quarry company has to pay taxes to the local council area where the exploitation site is located. in the forested parts of the country, their limited surfaces of exposure is an indication of an extensive basement substratum and due to their proximity to major construction sites, most of them are under exploitation. this is the case of the massif around limbe and tombel both in the south west region exploited by dangote, a cement manufacturing enterprise based in douala, the economic capital of the country. those in centre, littoral and south regions are mostly exploited by private quarry companies supplying to the major cities of yaounde, douala, ebolowa, etc. rock massifs within the city of yaounde, which constitute the target in the use of remote sensing in this study, can be considered as bare surfaces. their spectral responses in the visible range from above 200 in red, between 80 to 100 in green and below 50 in the blue. some of the surfaces are dark but their exposure and resistance to weathering provides them with a coat, and depending on its inclination it develops a clear grey colour over the years that have high reflection properties thereby facilitating their identification using remote sensing techniques. since 2014, the confederation of african football (caf) attributed the hosting rights of the african football competition to cameroon. yaounde alone was programmed to host two pools thus the construction of a new stadium went underway. apart from the stadium, new hotels were programmed for construction, old ones were to be renovated and expanded, new streets to be tarred, etc. thus justifying the high demand for quarry products. furthermore, yaounde is one of the fastest growing cities in cameroon. from the last census, its population was about 1,800,000 inhabitants, this population today is estimated at about 2,700,000 inhabitants. its spatial extension is presently estimated at 185km 2 . in recent years, i.e., from 2012, two additional cement industries have gone operational in www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 21 published by scholink inc. the country to supplement the lone one that exists since independence. it then became plausible to use remote sensing techniques to identify and map out all the rock massifs, potential sites for quarrying in order to satisfy the increasing demand this time around. the city of yaounde located within the cameroon southern plateau stretches on longitudes 11°24’51’’ to 11°34’ 29’’ east of the prime meridian and on latitudes 3°51’23’’ to 4°1’28’’ north of the equator. its average altitude is 760 metres above sea level constituting generally of elevated land that is surrounded by relatively lower altitudes. it is referred to as a city of 7 hills that have long passed to 11 hills due to its rapid expansion. figure 1 locates the city within the administrative setup of cameroon and on a landsat image. figure 1. location of yaounde in cameroon and on landast image yaounde yaounde as seen on landsat satellite image scene www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 22 published by scholink inc. 2. methods and techniques 2.1 data collection this study which aims at identifying with various techniques and mapping of the rock massifs in yaounde depended on the following data obtained through respective tools. the data was then treated in order to obtain the expected results. landsat 8 satellite image downloaded from the internet on which digital prospection of the rock outcrops was effectuated; geo-referenced ikonos image of yaounde of 1 m resolution from where all the streets were drawn; gps etrex 10 with a precision level of 3 m with which some samples of rock outcrops were located to be projected on the geo-referenced landsat image; a computer whose characteristics could enable the handling of remote sensing and gis processing of data. thus this mostly concerned the ram which is 4 gb, capacity of 500 gb of the hard disc; topographic map of yaounde at scale of 1/200 000 obtained from the national institute of cartography which served in orientating the movement for the registration of rock outcrop samples using the gps; remote sensing software (envi) where the processing of the landsat image was carried out; official vector files for cameroon obtained from the national institute of cartography which served in the location and delimitation of the study area; gis software (arcgis), where geo-referenced shapefiles for cameroon were treated and the samples projected. the choice of the landsat satellite image is simply because it is of multi-band and multi-date. it has a low resolution of 30 m whose scene covers a surface of 185x185 km. it is well adapted in assessing large surface phenomena and since yaounde is so vast horizontally, about 183.5 km 2 , it is for this reason it constituted the choice of this study. 2.2 data treatment to pre-treat the image, and given the fact that landsat image has 7 bands, a band combination was determined at 5, 4, 3 bands that provided a coloured image. geometrically, the scene was resized to extract the zone of interest at the size of 700x1130 pixels as shown on figure 3. the image was then opened in arcgis software and following the projection system that cameroon conforms to (utm wgs 84, zone 32 north), the sample rock massifs located with gps during fieldwork were projected in order to determine their spectral behaviour of the targeted zones (figure 4). this then acted as guide to do image interpretation and determine the rest of the rock massifs in yaounde. figure 2 shows a flow chart on how data was collected from the field. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 23 published by scholink inc. figure 2. flow chart of data collection and treatment figure 3. resized image from scene p185r057 of landsat with projected vector layer of yaounde and sampled rocks computer assisted image interpretation was carried out using iteration techniques comprising of direct and indirect clues such as general geologic setting, alteration zones, associated rocks, structure, lineaments, oxidation products, morphology, drainage and vegetation anomaly, since only rarely is it possible to directly pinpoint the occurrence and mineralogy of a deposit based solely on remote sensing data. locating exposed rocks relies primarily on knowledge of the general geological makeup of the area. therefore, a little basic landform geomorphology about the assumptions of rock exposures is relevant. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 24 published by scholink inc. to evaluate the different aspects of the application of remote sensing in identifying and mapping of rock massifs in yaounde, the approach focused on the lithological, structural and alteration mapping. emphasis was on multispectral analysis as such data can help identify and thematically map out areas of specific themes as is our case of rock massif exposures. to effectively carry this out, we relied on multi-thematic approach thus combing gis to remote sensing as they helped in analysing large number of spatial data with different attributes and formats in sub-setting the areas of interest where rocks outcrop. after effectuating unsupervised classification to determine the number classes that make up the image, sampling was done. this sampling did not take into consideration all the classes as revealed by the unsupervised classification. taking the rock massifs as the target, the rest of the classes were ignored. the supervised classification using band 5 was that of maximum likelihood. drone images were complimented in order to validate the samples collected during fieldwork as shown on figure 4. figure 4. procedure in sampling and validating rock massif samples with drone image 3. results 3.1 spectral signatures of rocks many studies have been conducted in the identification and mapping of rocks from satellite image analysis. this has mostly been in the visible short-wave infrared, mid-infrared and thermal infrared intervals. this establishes the scientific background for the interpretation of remotely sensed data. it should be noted that exposed rock surfaces give an insight into the relationship between original rock and superficial alteration products, allowing the development of reconnaissance criteria that may also be applied in other areas with similar environmental conditions. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 25 published by scholink inc. it has long been known that rocks can be distinguished from each other under ideal conditions by their spectral signatures in the thermal emission region of the spectrum (lahren et al., 1998; sabine et al., 1994). in general, the dominating features in sedimentary rocks are due to the additional presence of carbonate which produce absorption bands between 1.9 and 2.3 m (figures 5 a, b and c). all sedimentary rocks generally have water absorption bands at 1.4 and 1.9 m while clay shales have an additional absorption feature at 2.1-2.3m. the similarity of the spectra for a class of rocks, such as granite allows a composite signature to be generated which can be used as a representative for all granites. the broad absorption due to ferrous ion is prominent in rocks such as schists. water and hydroxyl bands are found in schists, marble and quartz (hunt & salisbury, 1976). basing on laboratory experiments, figure 10 confirms that rocks possesses the potential to be classified from airborne to satellite sensor data if sufficient spectral detail is generated. photo 1 illustrates the exposed rocks in some parts of yaounde. photo 1. exposed rock at mbankolo hill (11°31’27”/3°47’23”) www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 26 published by scholink inc. a) reflectance of sedimentary rocks b) thermal infrared transmission of igneous rocks c) reflectance of metamorphic rocks figure 5. spectral behaviour of rocks at different wavelengths of the spectrum www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 27 published by scholink inc. 3.2 sampled rocks projected basing on this scientific context, the classification of the landsat image enabled us to discriminate between zones of high concentration of exposed rocks and those of low concentration. furthermore, this discrimination also took into consideration bare ground, rock surfaces, roof tops of various colours and quarry sites. in the sampling process, three types of pixels could be identified in the classes of 32, 33 and 34 which all correspond to areas of bare ground with very little vegetation. these could either be built areas or areas susceptible to be exposed rock massifs. from this step, the radiometric amelioration through interactive stretching enabled us to discriminate between exposed rock massifs from the rest of similar spectral behaviour. table 1 shows the samples of the exposed rocks collected from the field while figure 6 shows the projection of these points on a geo-referenced high resolution ikonos satellite image covering yaounde. table 1. samples of exposed rocks registered with the gps within yaounde no. place x (in utm metres) y (in utm metres) 1 ngoa ekelle 777905,34 426436,28 2 gracam 778510,35 438564,41 3 yeye 1 777296 435663,82 4 yeye 2 777308,14 436359,57 5 golf 1 777083,81 430905,08 6 golf 2 777132,4 430972,38 7 golf 3 777070,38 431012,91 8 golf 4 777110,79 431101,66 9 nkolbisson1 771780,51 426646,62 10 nkolbisson2 770953,54 426634,73 11 arab constructors 770384,1 422271,84 12 akak 784648,78 441305,78 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 28 published by scholink inc. figure 6. projected verification points on a geo-referenced satellite image using band 5 of landsat tm that ranges from 0,845-0,885μm wavelength of the spectrum, the colours of green, blue and yellow on the image represent the pixels retained to indicate the exposure of rock massif which are either quarries under exploitation or not. it is noticed that these colours surround black spots on the image; these black spots were determined to be either bare ground, exposed rock, roof of houses, burnt areas or other esplanades without vegetation. discrimination had to be effectuated to isolate exposed rocks from the rest of similar spectral behaviour through filtering and interactive stretching (figure 7). on figure 8, the surrounding grey colour indicates vegetation and for the case of yaounde and its environs, this is forest vegetation. the green colour indicates cleared surfaces especially around dwellings, in some cases showing some coloured roof tops. the blue colour shows water or wet www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 29 published by scholink inc. surfaces. at the particular moment when the image was acquired, i.e., during the dry season, this indicates dry wet surfaces. the yellow colour mostly indicates houses or plots under construction. finally the black colour indicates rock outcrops as revealed by field investigations. figure 7. presentation of pixels potential representation of exposed rocks www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 30 published by scholink inc. photo 1. exposed unexploited rock in built up area photo 2. arab contractors quarry site figure 8. classified image of yaounde with the use of band 5 landsat tm www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 31 published by scholink inc. figure 9. exposed rock massifs in yaounde 4. analysis 4.1 clues to lithological mapping satellite images provide a broad based clue through which lithological information can be deduced. this lithological information includes general geologic setting, weathering/landform, drainage, structural features, soil, vegetation and spectral characteristics. in the case of sedimentary rocks for example, especially those exposed at hillsides or sloppy areas, or by folding and faulting as is the case of mount mbankolo in the nw of yaounde, bedding is one of the strongest clues to lithological composition in images. these linear features are long and even spaced, fewer in number (in comparison to those produced by foliation in metamorphic rocks) and constitute rather continuous ridges and valleys. another clue that led to the identification of exposed rock massifs in yaounde are the drainage density, drainage pattern and vegetation, even when the rocks are not exposed. yaounde being in a humid tropical forest with humid climate, the main clue to the presence of sandstone is the wide spacing of drainage and the roundness of topography. it should be noted that intrusive igneous rocks are generally massive, isotropic and homogenous which can easily be observed on satellite images. their shapes (batholiths, laccoliths, dykes, sills, etc.), dimension, distinct image tones and topography expression also contribute to their identification. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 32 published by scholink inc. in the case where our focus was on extrusive rocks especially those of igneous type (potential quarry sites), they could easily be delineated by distinctive landforms, differences in image tone, drainage pattern and vegetation distribution. in closely integrating them with surrounding sedimentary strata, intrusive igneous rocks were more subtly expressed than extrusive rocks. landsat images thus provided a suitable platform in the identification and mapping of these exposed rock massifs. 4.2 clues to structural mapping linear features can easily be identified on aerial photographs since they are often at larger scale. but these linear features are poorly seen on landsat image. we are not saying that exposed rocks are considered as linear features here but that linear features act as clues to the presence of exposed rock massifs. linear features indicate the form and position of folds, joints, faults, lithological contacts and other geologic features that may lead to the presence of exposed rocks. in general they indicate only immediate surface and near-surface conditions and are poor guides to concealed deposits. in yaounde one cannot find linear features that exceed 5 km, though most are short, less concentrated and spaced, they indicate the geometry of faults and other structures thereby providing a local structural pattern. they are useful in defining the target areas, local settings on which they may indicate exposed rocks but this has to be complimented by detailed field studies. some linear patterns provide the most favourable conditions for the presence of exposed rocks. these are the abandoned excavated escarpment quarry at ngoa ekelle neighbourhood, the exposed rock surfaces at the slopes of mount mbankolo (golf area), the isolated rock domes in bastos quarter, the rock surface of gracam and nkolbisson just to name but a few. before the image analysis, topographic map of yaounde at scale 1/200 000 provided the basis of reconnaissance for structural mapping. this optimized planning for fieldwork. but some difficulties were faced in integrating lineament map with exposed rock model as some of the features mapped as lineaments could not indicate the presence of exposed rocks. basing on studies conducted by akhavi et al. (2001), they integrated lineament structures derived from landsat images with a dataset of known occurrences in gis in order to better comprehend the exposed features. takir et al. (1999) correlated lineament intersection density to alteration and observed that lineament intersection density is nearly twice as dense as altered zones. it is only through this multi-technique approach that gained validity in the determination of exposed rocks in yaounde. 4.3 clues to alteration mapping remote sensing techniques have proven the feasibility to detect particular surface phenomena no matter the image used. but such techniques have differences in areas of application. for example it becomes more complex in built-up areas unlike in un-built areas. it should be noted that properties of some exposed rocks present diagnostic spectral features that enable their remote identification. it is certain weathering processes expose some surfaces such as hydrothermal alteration processes and mask the spectral response of underlying rocks with coatings. hence, it becomes imperative that field verification was performed in order to validate the existence of such rocks in certain areas of the city. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 33 published by scholink inc. the colour of the rocks played a key role in their identification. following the analysis of buckingham and sober (1983), when iron oxides are present in a rock, the rock colour can be red, brown, orange or yellow. on the other hand, if there are clay minerals, we have pale colours of yellow, violet, green, and beige. landsat tm stood as the base data for treatment because of the availability of mid-infrared bands in which the characteristic spectral features of most hydrothermal minerals are present. after the traditional band combination was effectuated, index analysis was performed which include bands 5 and 7 (clay mineral index), bands 3 and 1 (iron oxide index), and bands 5 and 4 (ferrous index). this index analysis discriminated between weathered and un-weathered rocks. given the fact that the detection of the exposed rocks was in a built-up area which posed as a handicap to landsat treatment, radiometric enhancement was applied as earlier proposed by fraser and green (1987). in this application, there were difficulties due to the similarities in the reflectance spectra of the rocks. thus, the effect of roof tops, other bare surfaces and esplanades could be discriminated. 5. discussion identification and mapping methods adopted by geo-engineers mostly focus on identifying anomalies that are associated with the target areas. such methods are complex and they need both analysis and integration of multi-thematic information which aid for decision taking over time and at different stages. this justifies why gis had to be integrated into this study. its usefulness is based on the fact that it was possible to analyse the large number of geo-referenced spatial data with different attributes and formats. target sites could be located following their geographic coordinates, distances from reference spots in the city to target sites easily determined thus establishing their accessibility and possibility to evaluate the surfaces covered by some of the exposed rocks. all these activities were possible thanks to the use of the gis, which did not only provide a geo-referenced surface but also registered exposed rock surfaces with the gps were project for sampling to be done. an interactive database could be developed which greatly facilitated access to information from each exposed rock in the city of yaounde. apart from the above, the developed database for this study can be projected over a time interval in order to assess the level of exposed rock exploitation certainly noticed if some of the surfaces are occupied by other phenomena. this data can equally be generated on other remote sensing data, geophysical data, geochemical data, geological data (structural, lithological), topographic data (dem) and perhaps mineral occurrence data for other analysis. this has the possibility of combining relational database and spatial data analysis though it was not the focus of this study. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 34 published by scholink inc. references akhavi, m. s., webster, t. l., & raymond, d. a. (2001). radarsat 1 imagery and gis modelling for mineral exploration in nova scotia, canada. geocarto international, 16, 55-61. https://doi.org/10.1080/10106040108542183 amos, b. j., & geenbaum, d. (1989). alteration detection using tm imagery. the effects of supergene weathering in arid climate. international journal of remote sensing, 10, 515-527. https://doi.org/10.1080/01431168908903889 andrews deller, m. e. (2006). facies discrimination in laterites using remotely sensed data. international journal of remote sensing, 27, 2389-2409. https://doi.org/10.1080/01431160600586050 bonham carter, g. f. (1994). geographic information systems for geoscientists: modelling with gis (p. 298). pergamon, uk. buckingham, w. f., & sober s. e. (1983). mineralogical characterisation of rock surfaces by hydrothermal alteration and weathering. application of remote sensing. economic geology, 78, 664-674. https://doi.org/10.2113/gsecongeo.78.4.664 buiten, h. j., & clevers, j. g. p. w. (1993). land observation by remote sensing: theory and applications of current topics in remote sensing. gorden and breach, 3, 32. crosta, a. p., & rabelo, a. (1993). assessing landsat tm for hydrothermal mapping in central western brazil. in proceedings of the 9 th thematic conference on geologic remote sensing (pp. 1053-1061). pasadena, california, usa. ferrand, w. h. (1997). identification and mapping ferric oxide and oxyhydroxide minerals in imaging spectrometer data of summitville colorado, usa, and the surrounding san juan mountains. international journal of remote sensing, 10, 1543-1552. https://doi.org/10.1080/014311697218269 fraser, a., huggins, p., reens j., & cleverly, p. (1997). a satellite remote sensing technique of geologic horizon mapping. international journal of remote sensing, 18, 1607-1615. https://doi.org/10.1080/014311697218313 fraser, s. j., & green a. a. (1987). a software defoliant for geological analysis of band ratios. international journal of remote sensing, 8, 525-532. https://doi.org/10.1080/01431168708948659 gillespie, a. (1986). lithologic mapping of silicate rocks using tims. in proceedings of the tims data users’ workshop (pp. 29-44). jpl publication 86-38 (pasadena: jet propulsion laboratory). harris, j. r. (1991). mapping of regional structures of eastern nova scotia using remote sensed images. application for regional tectonics and gold exploration. canadian journal of remote sensing, 17, 122-135. https://doi.org/10.1080/07038992.1991.10855286 https://doi.org/10.1080/10106040108542183 https://doi.org/10.1080/01431168908903889 https://doi.org/10.1080/01431160600586050 https://doi.org/10.2113/gsecongeo.78.4.664 https://doi.org/10.1080/014311697218269 https://doi.org/10.1080/014311697218313 https://doi.org/10.1080/01431168708948659 https://doi.org/10.1080/07038992.1991.10855286 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 35 published by scholink inc. hubbard, b. e., crowley, j. k., & zimbelman, d. r. (2003). comparative alteration mineral mapping using visible to shortwave infrared (0.4-2.4 mm) hyperion, ali, and aster imagery. ieee transactions on geoscience and remote sensing, 41, 1401-1410. https://doi.org/10.1109/tgrs.2003.812906 hunt, g. r., & salisbury, j. w. (1976). visible and near infrared spectra of minerals and rocks: xii metamorphic rocks. modern geology, 5, 219-228. lahren, m. m., schweikert, r. a., & taranik, j. v. (1988). analysis of the northern sierra accreted terrain, california with airborne thermal infrared multispectral scanner data. geology, 16, 525-528. https://doi.org/10.1130/0091-7613(1988)016<0525:aotnsa>2.3.co;2 lillesand, t. m., kiefer, r. w., & chipman, j. w. (2004). remote sensing and image interpretation (5th ed., p. 445). john wiley and sons, new york. mickus, k., & johnson, e. (2001). mapping sedimentary and volcanic units within and surrounding petrified national park, arizona using landsat 5 and spot panchromatic data. international journal of remote sensing, 22, 1919-1935. https://doi.org/10.1080/01431160121297 rajesh, h. m. (2004). application of remote sensing and gis in mineral resource mapping, an overview. journal of mineralogical and petrological sciences, 99, 83-103. https://doi.org/10.2465/jmps.99.83 sabine, c., realmuto, v. j., & taranik j. v. (1994). quantitative estimation of granitoid composition from thermal infrared multispectral scanner (tims) data. desolation wilderness northern sierra nevada, california. journal of geophysical research, 99, 4261-4271. https://doi.org/10.1029/93jb03127 sabins, e. f. (1996). remote sensing: principles and interpretation (3rd ed., p. 32). freeman and co., new york. salisbury, j. w., & hunt, g. r. (1974). remote sensing of rock types in the visible and near infrared. in proceedings of the 9 th international symposium on the remote sensing of the environment (vol. iii, pp. 1953-1958). siegal, b. s., & goetz, a. f. h. (1997). effects of vegetationon rock and soil discrimination. photogrametrric engineering and remote sensing, 43, 191-196. https://doi.org/10.1109/tgrs.2003.812906 https://doi.org/10.1130/0091-7613(1988)016%3c0525:aotnsa%3e2.3.co;2 https://doi.org/10.1080/01431160121297 https://doi.org/10.2465/jmps.99.83 https://doi.org/10.1029/93jb03127 energy and earth science vol. 5, no. 4, 2022 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 original paper my research collaborations with australian scientists over the past half century robert cooper liebermann 1 1 mineral physics institute and department of geosciences, stony brook university, stony brook, ny, usa received: september 18, 2022 accepted: september 27, 2022 online published: october 27, 2022 doi:10.22158/ees.v5n4p1 url: http://dx.doi.org/10.22158/ees.v5n4p1 abstract over the past half century, i have maintained research collaborations with australian scientists while pursuing an academic career focusing on scientific investigations of the physical properties of minerals at high pressures and temperatures. from 1970-1976, i was a member of the research faculty of the australian national university; initially in the department of geophysics and geochemistry and later in the research school of earth sciences. in subsequent years, i have maintained connections with many laboratories in australia in addition to the anu, including those in brisbane, hobart, melbourne, perth and sydney. the objective of this paper is to relate this history. keywords mineral physics, australian scientists, research collaborations 1. introduction over the past decade, i have concentrated on writing papers on my history pursuing a scientific career in mineral physics. recently, i have published papers on my research collaborations with french, czech, chinese, russian and english scientists in the international journal of geosciences (liebermann, 2021a, 2021b, 2021c; 2022a, 2022b) and with german scientists in the journal of energy and earth sciences (liebermann, 2022c). this new paper is of a similar genre. finally, i document my personal history with australia and australians. in 1970, i established the first mineral physics laboratory in australia at the australian national university [anu] under the auspices of a. e. (ted) ringwood. over the next 6 years, we published 25 research papers in peer-reviewed journals, many of them in collaboration with my graduate students ian jackson and leonie jones. this research was focused on measurements of sound velocities in minerals [and their structural analogues] at high pressures and temperatures, as well as studies of www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 2 published by scholink inc. melting and elastic shear instabilities in materials and applications of these experimental data to interpreting seismic models of the earth’s interior. i have documented this birth of mineral physics in australia in a previous paper (liebermann, 2020); this new paper extends this history for another 46 years to the present day. 2. the lamont years in the 1960s in 1969, when i was a graduate student at columbia university’s lamont geological observatory, my advisor orson anderson attended an international conference at the australian national university [anu] in canberra, australia to deliver our joint paper on lattice dynamic calculations of the elastic moduli of cubic lattices (anderson & liebermann, 1970); this was the meeting at which a. d. wadsley collapsed on the stage and died while frank press was delivering his talk (t. takahashi, personal communication, march 2013). during that meeting, ted ringwood informed anderson that he was looking for a postdoc to set up an ultrasonics laboratory; subsequently, richard o’connell declined to apply for this job and i was offered the post. enroute from lamont to canberra, i spent 10 months as a postdoc at the seismological laboratory at caltech; during that period, i profited from advice and guidance on equipment for my new ultrasonics lab at the anu from hartmut spetzler and o’connell. while i was still at lamont, frank stacey from the university of queensland was a visiting scientist. he strongly encouraged me to accept the post at the anu; but he cautioned me to avoid the wife-swapping which was then rampant at the university flats in garran, a suburb of canberra, where non-tenured scientific staff often resided. at the birch symposium at harvard university in 1970, i met ted ringwood and we laid plans to purchase equipment so that it would be on campus when i arrived in late september. john jaeger [then the chair of the department of geophysics and geochemistry at the anu] visited the anderson lab at lamont later that year and told me that he hoped i knew how to operate and maintain all that electronic equipment as the anu did not have suitable staff to do so; that turned out to be apocryphal as the department not only had an excellent machine shop but several very talented electronic staff. in addition, ringwood and david green were blessed with two superb senior technical officers, alan major and william hibberson, who were tremendous assets to my new research program (figs. 1a, b). www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 3 published by scholink inc. figure 1a. alan major at lathe fabricating cell parts for high-pressure experiments inn laboratory of ted ringwood figure 1b. bill hibberson (right) and paul willis preparing for high-pressure experiment in laboratory of dave green www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 4 published by scholink inc. 3. the anu years from 1970-1976 in september 1970, i set off for canberra with my wife and one-year old daughter karen. figure 2. my wife barbara and our daughter karen [wearing her new lei] during a layover in honolulu enroute to australia in september 1970 a. arrival and first years at the anu in october 1970, my wife barbara and i arrived in canberra with our one-year old daughter karen in tow. as ted ringwood was overseas, david green welcomed us and installed us in apt. #1 of the garran university flats in the woden valley. john cleary led the search for a car, ending in a 2-door datsun coupe [a little difficult to install a baby carrier in the rear seat]. on one of my first days in the department of geophysics and geochemistry, “prof” jaeger introduced me to the faculty and students and offered me a yard of ale with instructions to down it in one gulp; with some difficulty, i passed this initiation rite. the ultrasonic equipment ordered when i was still at lamont had been delivered, and with the help of electronics specialist eddie penikis, i began to set up the new ultrasonics laboratory. the primary objective of this new laboratory was to perform ultrasonic measurements of sound velocities in polycrystalline specimens of mantle minerals or their crystal chemical analogues [principally germanates]. with alan major, we began to learn how to hot-press polycrystalline specimens suitable for ultrasonic measurements of elastic wave velocities, using synthetic powders prepared by alan and bill hibberson. the first specimens were fabricated in a piston-cylinder apparatus at pressures less than 35 kbar [3.5gpa] and temperatures up top 1200ºc; we initially focused on germanate analogues of silicate mineral phases. we tested the polycrystals in the ultrasonics lab using a polishing jig and specimen holder fabricated in the department machine shop [both of which are still currently in use in our lab at stony brook]. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 5 published by scholink inc. figure 3. polishing jig used to prepare polycrystalline specimens for ultrasonics experiments the fabrication of these polycrystalline samples was initially done in a piston-cylinder apparatus at pressures up to 35 kbar (3.5 gpa); subsequently we used girdle, belt and simple squeezer apparatus, eventually achieving pressures above 100 kbar in these hot-pressing experiments (gwanmesia et al., 1993). while awaiting the arrival of a hydrostatic high-pressure vessel from the harwood company in the u. s., mervyn paterson generously offered me the use of one of his pressure vessels to conduct my initial experiments. the first velocity experiments at high pressure were conducted in a liquid-media apparatus to 7.5 kbar (0.75 gpa) in his laboratory with assistance of bill mcintyre, prof jaeger’s personal machinist; bill had been assigned by jaeger to work with me while jaeger was “wintering” in northern hemisphere summer. ringwood was very surprised to learn about this assignment but had no basis to object. the first results on rutile and spinel compounds were obtained by the pulse transmission (“time-of-flight”) technique and reported at the iugg meeting in moscow, russia in august 1970, less than one year after establishing new ultrasonics lab at the anu, with technical assistance of new electronics technician doug mayson (liebermann, 1972). in these “time-of-flight” measurements were collected to 7.5 kbar at room t and the data at highest p were taken to represent pore free specimen (liebermann, 1973, 1974, 1976; liebermann & mayson, 1976; lieberman, ringwood & major, 1976; lieberman & ringwood, 1977; jackson, liebermann & ringwood, 1978). on the night before i left for moscow, alan major, bill hibberson and bill mcintyre invited me to the tea room in the department to play bridge and drink beer as a goodwill send-off. the next advance in ultrasonics was to employ the pulse superposition technique to obtain more precise measures of travel times to 7.5 kbar. values reported were those “back-extrapolated” to 1 bar to obtain velocities representative of a pore-free specimen; these data were then compared with results from www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 6 published by scholink inc. single crystals in other labs (liebermann, ringwood & major, 1976; jackson, lieberman & ringwood, 1978; lieberman, 1972, 1973; liebermann & mayson, 1976). in later experiments, the measurements of velocities using the pulse superposition technique were sufficiently precise to allow determination of the pressure derivatives. my six years at the anu were a fantastic period of exposure to high-pressure geosciences. in early 1971, frank stacey from the university of queensland stacey invited me to give a paper at the australian-new zealand association of science [anzas] in brisbane. later, he recommended to ian jackson and leonie jones, both graduates of the physics department of the university of queensland, that they apply for a graduate fellowship to study at the anu under my supervision. when they arrived to begin their graduate research programs, ringwood was nervous about their lack of exposure to earth sciences, so he insisted that they take “remedial” courses in the geology department. after both completed introductory geology, jackson took the 3rd year mineralogy course and topped the class; ringwood never raised the issue again. both leonie jones and ian jackson can be seen in the photo of the rses staff in figure 4. in 1973, the anu established the research school of earth sciences [rses] which provided the opportunity for the department of geophysics and geochemistry to move out from under the control of the research school of physical sciences. anton hales arrived from the university of texas at dallas to become the founding director of the rses; over the next three years, i learned much from hales about scientific leadership and administration. figure 4. group photo of staff at the research school of earth sciences in the hales era circa 1975 note. leonie jones (fifth from left) and ian jackson (8 th from the right) in front row and bob in second row. anton hales in first seated row in suit jacket. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 7 published by scholink inc. when the department of geophysics and geochemistry evolved to become the research school of earth sciences [rses] in 1973, it became necessary to establish a faculty board and produce bylaws; i helped ian macdougall to draft these bylaws and we served together on the faculty board. during one of the board meetings, some members challenged director hales on the appropriateness of his contract with the u. s. department of defense [to install and operate seismic stations on the australian continent]; hales abruptly adjourned the meeting and deputized me to talk to faculty board members and convince them that it was hales’ right to hold such a contract. with ian mcdougall, i also initiated an annual summer school to encourage undergraduates from australian universities to consider pursuing graduate study at the rses. this recruiting effort involved trips to the geology and geophysics departments of universities in melbourne, brisbane, adelaide and sydney. as a result of this program, more than a half dozen undergraduates came to canberra to pursue phds in the school of earth sciences. as there were no formal courses required for graduate students in the institute of advanced studies at the anu, i initiated a series of informal seminars on monday evenings for ian jackson and leonie jones. in addition to reading and discussing current geophysical literature, we profited from participation of visiting scientists, including don anderson, adam dziewonski and ralph lapwood. it was during that era that geophysicists were exploring use of inverse theory to analyze observational data to obtain velocity and density models of the earth’s interior. to help us understand this approach, prof. lapwood kindly offered a set of tutorial lectures on inverse theory, using the book by cornelius lanzcos. during these seminars, i also had extensive contact with john cleary and others in their seismological group. after arriving in 1973 to become the first director of rses, anton hales became a regular attendee at our weekly seminars. in addition to bringing his decades of geophysical knowledge, he provided funds for me to buy cheese and crackers to sustain us through the evening [and to leaven the beer which we drank]. b. research of graduate students ian jackson and leonie jones ian jackson initially worked on melting and elastic shear instabilities in alkali halides (jackson & liebermann, 1974) and engaged in some hard-sphere modeling of melting with bob watts of the research school of physical sciences. ian later studied the disproportionation of spinels into mixed oxides and revealed significance of cation configuration and implications for the mantle (liebermann, jackson & ringwood, 1977) and the elastic properties of (mgxfe1-xo) solid solutions (jackson, liebermann & ringwood, 1978). his ph. d. dissertation in 1976 was entitled “phase equilibria and elastic properties in silicate analogue systems: studies of melting and polymorphic phase transformations”. leonie jones initially worked on the elastic and thermal properties of fluoride and oxide analogues with the rocksalt, fluorite, rutile, perovskite structures (jones & liebermann, 1974) and later the elasticity of aluminate, titanate, stannate and germanate compounds with the perovskite structure (liebermann, jones & ringwood, 1977). www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 8 published by scholink inc. her ph.d. dissertation (1976) was entitled “high-temperature elastic properties of fluoride and oxide analogues”. we also worked on a number of other mineral physics projects: elasticity systematics and applications to interpretation of earth models (liebermann, 1973a, 1973b, 1973c). hot-pressing of polycrystalline specimens of high-pressure phases (liebermann et al., 1974)—presented 4th international conf. high pressure-25-29 nov. 1974, kyoto, japan. see also gwanmesia et al. (1993). elasticity of anorthite and nature of the lunar crust (liebermann & ringwood, 1976). elasticity of stishovite—most challenging project to hot-press and measure sound velocities in polycrystalline stishovite (liebermann, ringwood & major, 1976; liebermann & ringwood, 1977). no elastic anisotropy was observed in these specimens; their velocities were consistent with later brillouin scattering data from don weidner’s laboratory (weidner et al., 1982). c. related research [1971-1976] in 1976, i worked on phase equilibria and elastic properties of pyrolite model for the oceanic upper mantle with david green, who presented our paper at the iugg international congress in grenoble, france (green & liebermann, 1976). ringwood expressed surprise that i was collaborating with his colleague and competitor when i was working “under the supervision of ringwood” (figure 5). dave later moved to hobart to become the chair of geology at the university of tasmania, and subsequently returned to the anu to take up the post of director of the research school of earth sciences. while i was conducting mineral physics experiments in the laboratory of ted ringwood, ian nicholls (my friend and junior faculty colleague) was pursuing high-pressure petrology experiments in the laboratory of dave green. ian later moved to melbourne to join the faculty of the new department of geology at monash university (the department established by bruce hobbs—see below). our family visited ian’s family in melbourne in the 1970s and later in 1992 (see photos with australian animals below). in 1975, professor kenzo yagi from the hokkaido university visited the anu as a guest of ted ringwood (see figure 5). i subsequently met yagi-sensei (sometimes referred to as “big yagi”) at many international conferences. he was a dedicated photographer and my photos do not do justice to his talents. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 9 published by scholink inc. figure 5. visit of professor kenzo yagi of hokkaido university to rses in 1975 note. l to r: david green, ted bence from stony brook, don anderson from caltech, ted ringwood, nobuko yagi-wife of kenzo yagi and mother of takehiko yagi, and bob. during my time at the australian national university from 1970 to 1976, don anderson spent a study leave in the laboratory of ted ringwood in 1975. see photo above of don and ted with others on the anu campus. don and his family (wife nancy, daughter lynn and son lee) rented a house across the street from ours in the university complex in garran. we had the opportunity to introduce their kids to kangaroos, cockatoos and koalas at the tidbinbilla nature preserve, skiing in the snowy mountains and beach trips to the south coast of australia. see photo of our families at a picnic on lake burley-griffin in canberra (figure 6). figure 6. left to right: karen and barbara liebermann, lynn and lee anderson, erica liebermann, don and nancy anderson www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 10 published by scholink inc. lynn reminded us that we had to abort one picnic at tidbinbilla when we were threatened by mating kangaroos and intimidated by the chest-thumping of the males. lee recalls games of american touch football in the commons of the garran compound and a homemade cassette of bawdy australian songs we sent them home with so they wouldn’t get homesick. during his visit to the anu, don gave me some important career advice. although i was having a very productive period in ringwood’s lab and with ian jackson and leonie as graduate students, i was still in a non-tenure track position after 5 years with no apparent chance of promotion to tenure. don urged me not to stay too long and to explore opportunities for returning to the u. s. in a tenure-track position. i took his advice and joined the faculty at stony brook university in 1976, from which i formally retired in 2014, but continue as a research professor. at the 1973 meeting of the international association of seismology and physics of the earth’s interior (iaspei) in lima, peru, charles drake encouraged me to organize a workshop in eastern europe, so that young scientists from countries in the eastern bloc could attend. with my czech colleagues, vladislav babuška, jaroslava plomerova and vlastimil červený, i convened the first of these workshops in 1976 at the castle of liblice in eastern bohemia on “anisotropy and heterogeneity of the lithosphere” (babuška & liebermann, 1977). anisotropy and heterogeneity of the lithosphere at castle of liblice, czechoslovakia, june 1976 conveners: v. babuška, j. plomerová, v. červený and r.c. liebermann. the only australian attendee at liblice was frank stacey, who engaged in a vigorous debate with other theoreticians on the subject of the volume dependence of the elastic gruneisen parameter. from the presentations by orson anderson, francesco mulargia, enzo boschi, frank stacey, and vladimir zharkov, the audience concluded that: “thermal regime of earth’s interior depends on definition of grüneisen’s parameter gamma, the correct formulation of which is one of the principal unsolved problems in high-pressure physics. some indications from debate that gamma depends more critically on author than volume”. d. interactions with other research groups in the rses i was welcomed into the rock mechanics research group of mervyn paterson and bruce hobbs. there i met and interacted with jim boland and john fitzgerald, specialists in transmission electron microscopy, as well as rob coe (visitor from santa cruz), and graduate students gordon lister and ide van der molen. boland later spent a sabbatical year at stony brook bringing a dedicated introduction of electron microscopy to my research group; his tutelage of my graduate student, anne remsberg, was one of the first experiments performed in our new high-pressure laboratory. on several occasions, mervyn and his wife katalin hosted dinners at their home to which my wife barbara and i were invited and where we enjoyed sampling the excellent wines in meryvn’s cellar; bruce hobbs had a cellar too, but it was always empty because he could not afford to keep the wine long enough. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 11 published by scholink inc. hobbs ultimately left the anu to set up a geology department at monash university in melbourne (mainly seduced by alec mclaren); after a few years, he became tired of administration and joined the csiro and later on to become the chief scientist of western australia in perth. although i never worked directly with ross taylor, he was a constant source of encouragement as i pursued my career at the anu; first in the department of geophysics and geochemistry and later in the research school of earth sciences. i am grateful for his wise counsel, especially when we served together on the faculty board of the rses, then chaired by anton hales. i remember one tense board meeting when the members challenged director hales right to hold a research contract from the u. s. department of defense; hales abruptly adjourned the meeting and tasked me with the job of convincing the other board members that he could accept the dod funding (ross was a valued ally in that lobbying effort). i also appreciated the advice ross would offer me in understanding how best to deal with the generous but domineering personality of ted ringwood. barbara and i had the pleasure of hosting ross and his wife noel at our university apartment in the garran flats on several occasions; i always marveled at ross’ manner of speech, which was often somewhat garbled early in the evening, but seemed to get smoother after we imbibed some wonderful australian wine. in december 1976, i departed canberra with my family to take up a faculty appointment in the department of earth and spaces sciences at stony brook university. when we were leaving canberra, ted ringwood unexpectedly appeared. i thanked him for coming to see us off, to which he replied: “i wanted to be sure you left the country”. 4. post-1970 research collaboration between anu and stony brook after six years at the anu, i began to think about longer term career opportunities. as there were no options open at the anu for tenure-track positions (until the last moment), i began to explore jobs back in the us, and i was lucky enough to be offered a position at stony brook following a search led by donald weidner (who apparently was not afraid to recommend hiring another mineral physicist). charles prewitt, who was then on sabbatical leave at monash university in melbourne, strongly encouraged me to accept, as did his colleague a. e. (ted) bence, who was visiting the anu at that time, and orson anderson, my ph.d. advisor. when i arrived at stony brook, two of my first purchases were a hydraulic press system from harwood engineering and a girdle-anvil high-pressure apparatus from pressure systems research. this equipment was delivered in september 1977 and installed in room 375 of the ess building with the help of tony vidmar (our new technician), al catalano (machinist) and alan major (consultant from ringwood’s lab at the anu (see figure 7]). with this system, we could achieve pressures of 60 kbar (6 gpa). www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 12 published by scholink inc. figure 7. al catalano [machinist extraordinaire] and alan major from anu with tony vidmar checking hydraulic connections to press after a postdoctoral appointment in the laboratory of thomas ahrens at caltech, ian jackson returned to the anu in the late 1970s to take up a faculty position in ted ringwood’s petrochemistry research group, later transferring to the petrophysics group of mervyn paterson in the research school of earth sciences. ian and mervyn adapted paterson’s gas-medium deformation apparatus to perform acoustic attenuation experiments (figure 8). figure 8. ian jackson and mervyn paterson with apparatus to measure acoustic attenuation circa 1990 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 13 published by scholink inc. in the ensuing years, i have continued my association with the rses at the anu, especially during a period of the 1990s when ian jackson and i had an international cooperative grant between the australian research council and the national science foundation (nsf) in the us. this grant supported collaborative research using the ultrasonic interferometry techniques developed by jackson and his colleagues to measure sound velocities in polycrystalline specimens of mantle minerals to 3 gpa in their modified piston-cylinder apparatus. from the stony brook side, the specimens were fabricated by gabriel gwanmesia and baosheng li in our high pressure laboratory and the ultrasonic data obtained by sally rigden at the anu during visits by gwanmesia and the author (figures 9a, 9b); (rigden et al., 1988; gwanmesia et al., 1990; rigden et al., 1991, 1992, 1994; li et al., 1996). with regard to gwanmesia’s visits to australia, the first in 1989 was to measure the wadsleyite and ringwoodite that resulted in the science and nature publications, respectively (gwanmesia et al., 1990; rigden et al., 1991). he returned to australia in 2003 for his sabbatical during which he studied the elasticity of pyrope to 1000 k at 300 mpa in the internally heated gas-medium apparatus reported in gwanmesia et al. (2007). figure 9a. gabriel gwanmesia and sally rigden in ian jackson’s laboratory at the anu figure 9b. sally rigden from the anu with gabriel gwanmesia and bob in high pressure laboratory at stony brook in 1991 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 14 published by scholink inc. in 1993, i was a candidate for director of the rses, but the administration at stony brook convinced me to stay and thus i was able to continue my role as the co-director of the nsf center for high pressure research (chipr). that also led to the second phase of our collaboration with the jackson team at the anu. in 1994, baosheng li, then a graduate student and now a professor in the department of geosciences, developed techniques to incorporate ultrasonic interferometric measurements of sound velocities in situ in the kennedy-getting high-pressure apparatus in collaboration with ian jackson (my first graduate student and subsequently the director of the research school of earth sciences at the anu; see figures 10a, 10b). this pioneering development provided the opportunity to conduct sound velocity experiments to pressures of 10 gpa and was exploited over the next few years by many graduate students and postdocs. figure 10a. in the following year, ian jackson spent 6 weeks in our laboratory working with baosheng li on interfacing the anu ultrasonic interferometry system with the 1000-ton split-cylinder apparatus of the kennedy-getting type (li, jackson, gasparik & liebermann, 1996) www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 15 published by scholink inc. figure 10b. baosheng li and kennedy-getting press with walker-type module in high pressure lab in 1994 on a sabbatical leave in 1976 at the james cook university in townsville, queensland, my stony. brook colleague charlie prewitt met a young australian graduate student, john parise, with whom he enjoyed a long period of collaboration (and who later succeeded charlie in the crystallography chair at stony brook). with ken schwartz, bob shannon from dupont and dave cox from brookhaven national laboratory, parise and prewitt pursued the high-pressure synthesis of platinum oxides for fuel cell cathodes and characterization by x-ray and neutron diffraction. in 1995, jennifer kung spent six months at stony brook working with gabriel gwanmesia on the synthesis of polycrystalline specimens of scalo3-perovskite for her thesis at the anu with sally rigden and ian jackson (kung et al., 2000a, 2000b). during her postdoctoral stay at stony brook from 2000-2005, jennifer returned to the anu to perform a high-temperature acoustics study of orthoenstatite in jackson’s lab (figure 11) (kung et al., 2011); she was accompanied by one of john parise’s graduate students sytle antao who performed similar high-temperature studies on magnesium ferrite spinel (antao et al., 2007). in the most recent collaboration between the anu and stony brook, ting chen and her colleagues measured the sound velocities of polycrystalline coesite at high pressure and temperature in baosheng li’s laboratory (ting chen et al., 2017). using a specimen hot-pressed by the author in a girdle—anvil apparatus in 1975, and so very “well-aged” (liebermann et al., 1974). www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 16 published by scholink inc. figure 11. jennifer kung with high-temperature, ultrasonic apparatus in laboratory of ian jackson at the rses at the anu in the my most recent visit to australia in 2006, my wife and i. were hosted by maggie and ian jackson at their cottage on lilli pilli beach, which we remember fondly from our many family visits there in 1970 to 1976 (figure 12). figure 12. ian jackson and bob at lilli pilli beach, australia 2006 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 17 published by scholink inc. 2008-2013—global center of excelllence (g-coe) at ehime university in matsuyama. from 2008-2013, ian jackson and i (the author) of the advisory committee for the global center of excellence (g-coe) program at ehime university in matsuyama led by tetsuo irifune (figures 13-15). figure 13. advisory committee and japanese members of the global center of excellence (g-coe) at ehime university. bob in front row with ian jackson standing behind www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 18 published by scholink inc. figure 14. lunch for advisory committee of g-coe in 2013 note. seated: shun-ichiro karato, takehiko yagi, bruce buffett, ian jackson, bob and zhenmin jin; standing: craig bina and tetsuo irifune. figure 15. bob and ian at advisory committee meeting in matsuyama of global center of excellence in 2013 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 19 published by scholink inc. 5. personal life in australia as documented above, our family of 3 moved to canberra in october 1970 and lived in the university flats in garran for the next 6 years. during that period, we had two more children, a daughter erica born in 1973 and a son mark born in 1976; both of whom now bear dual citizenship in australia and the united states. our oldest daughter karen, who spent 6 of her first 7 years in australia, is very jealous of this dual citizenship. among the highlights of our time is australia were regular visits to the wildlife refuge at the tidbinbilla nature reserve in the nearby brindabella mountains. the principal attraction at the tidbinbilla was the presence of numerous kangaroos who were sufficiently tame that our children could pet them and be photographed with them, as you can see in the following photos when they were infants and later when they were young adults. figure 16. baby karen with her favorite kangaroo in 1971 at age 2 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 20 published by scholink inc. figure 17. karen scratching the chin of a kangaroo in 1974, at age 5 figure 18. karen sharing one of her kangaroos with her uncle tom in 1974 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 21 published by scholink inc. figure 19. erica at age 1 with barbara and uncle tom in 1974 figure 20. bob with son mark, age 3 months, in 1976 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 22 published by scholink inc. our other favorite family activity while living in canberra were regular trips to the beaches of the atlantic coast, which were only a 2-hour drive away. one of our favorites was lilli pilli beach, where karen and her sister erica enjoyed playing in the sand. figure 21. barbara in the woods overlooking lilli pilli beach (see also figure 12 above) figure 22. erica and karen on lilli pilli beach in 1974 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 23 published by scholink inc. figure 23. our family on lilli pilli beach in 1975 in 1992, we returned to australia with our young adult children and, once again, enjoyed seeing the wildlife of our adopted country, as well as visiting our friends, ian and chris nicholls, in melbourne. it was a pleasure to introduce our kids to the crimson rosellas and kookaburras, as well as the kangaroos at park on wilson’s prom in victoria (figures 24-25). figure 24a. karen with crimson rosellas www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 24 published by scholink inc. figure 24b. kookaburras figure 25a. 1992: erica at age 19 with kangaroo figure 25b. 1992: mark at age 16 with kangaroo www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 4, 2022 25 published by scholink inc. 6. dedication i would like to dedicate this paper to alan major and bill hibberson, senior technical officers in the department of geophysics and geochemistry of the australian national university, who were instrumental in ensuring the success of the experiments in our new ultrasonics laboratory in canberra in the 1970s. 7. conclusion this paper summarizes my research collaborations with australian scientists over the past six decades. i have presented both the scientific achievements and the personal connections which resulted from these collaborations. acknowledgements i am grateful to ian jackson, leonie jones, jennifer kung, gabriel gwanmesia jim boland, bruce hobbs, frank stacey, sally rigden, hiroyuki kagi, eiji ohtani and tetsuo irifune for their correspondence and contributions to this historical paper. my collaboration with my australian colleagues has been supported by research grants from the nsf geophysics program and the nsf science and technology center for high pressure research (chipr). this report was written with support from a research grant to baosheng li and myself from the national science foundation (ear-1524078). conflicts of interest the author declares no conflicts of interest regarding the publication of this paper. references anderson, o. l., & liebermann, r. c. 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(1972). compressional velocities of polycrystalline olivine, spinel and rutile minerals, earth planet. sci. letters, 17, 263-268. https://doi.org/10.1016/0012-821x(72)90285-3 liebermann, r. c. (1973). elastic properties of germanate analogues of olivine, spinel and beta polymorphs of (mg, fe)2sio4. nature, physical sciences, 244, 105-107. https://doi.org/10.1038/physci244105a0 liebermann, r. c. (1973). elasticity of the olivine-spinel and olivine-beta phase transformations and the 400 km. discontinuity of the mantle. j. geophys. res., 78, 7015-7017. https://doi.org/10.1029/jb078i029p07015 liebermann, r. c. (1974). elasticity of pyroxene-garnet and pyroxene-ilmenite phase transformations in germanates, phys. earth planet. interiors, 8, 361-374. https://doi.org/10.1016/0031-9201(74)90046-6 liebermann, r. c. (1976). elasticity of ilmenites, phys. earth planet. interiors, 12, 5-10. https://doi.org/10.1016/0031-9201(76)90003-0 liebermann, r. c. 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(1976). elasticity of stishovite, earth planet. sci. letters, 32, 129-140. https://doi.org/10.1016/0012-821x(76)90051-0 liebermann, r. c., ringwood, a. e., mayson, d. j., & major, a. (1974). hot-pressing of polycrystalline aggregates at very high pressures for ultrasonic measurements, proc. (pp. 495-502). 4th international conf. high pressure-25-29 nov. 1974, physico-chemical society of japan, kyoto, japan. rigden, s. m., gwanmesia, g. d., & liebermann, r. c. (1994). elastic wave velocities of a pyrope-majorite garnet to 3 gpa, phys. earth planet interiors, 84, 35-44. https://doi.org/10.1016/0031-9201(94)05060-0 rigden, s. m., gwanmesia, g. d., fitzgerald, j. d., jackson, i., & liebermann, r. c. (1991). spinel elasticity and seismic structure of the transition zone of the mantle . nature, 354, 143-145. https://doi.org/10.1038/354143a0 rigden, s. m., gwanmesia, g., jackson, i., & liebermann, r. c. 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(1982). the single-crystal elastic moduli of stishovite. j. geophys. res., 87, 4740-4744. https://doi.org/10.1029/jb087ib06p04740 https://doi.org/10.1016/b978-0-12-468750-9.50031-0 https://doi.org/10.1111/j.1365-246x.1977.tb01335.x https://doi.org/10.1016/0031-9201(77)90152-2 https://doi.org/10.1016/0012-821x(76)90051-0 https://doi.org/10.1016/0031-9201(94)05060-0 https://doi.org/10.1038/354143a0 https://doi.org/10.1029/gm067p0167 https://doi.org/10.1029/gl015i006p00605 https://doi.org/10.1029/jb087ib06p04740 energy and earth science vol. 5, no. 3, 2022 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 26 original paper mathematical modeling and review of pine wilt disease abdul ghaffar khan 1 , imran *2,3 , hayat zada 2 , ansar hussain 2 & tariq mahmood 4 1 department of basic sciences, university of engineering and technology, peshawar, pakistan 2 government of khyber pakhtunkhwa, agriculture extension wing, kp, pakistan 3 department of agronomy, the university of agriculture, peshawar, pakistan 4 department of bioinformatics/agriculture, hazara university, mansehra, kp, pakistan * imran, e-mail: imranagrarian@aup.edu.pk received: july 21, 2022 accepted: august 16, 2022 online published: september 7, 2022 doi:10.22158/ees.v5n3p26 url: http://dx.doi.org/10.22158/ees.v5n3p26 abstract pine wilt disease (pwd), caused by the pinewood nematode (pwn) bursaphelenchus xylophilus, causes significant losses in coniferous forests in eastern asia, including japan, china, and south korea, as well as western europe, including portugal. the results of the research papers given at the international symposium on pine wilt disease (iufro working party meeting 4.04.03) in nanjing, china, in july 2009 are summarized in this article. the basic themes discussed included pine wilt disease (pwd), the pinewood nematode (pwn) bursaphelenchus xylophilus, and other pwn-associated microorganisms that play a significant role in pwd, such as bacteria (e.g., pseudomonas fluorescens). the majority of the papers are based on pwd-pwn research in east asia and russia. the following are some of the specific topics covered: 1) fundamental concepts of pwd development, 2) pathogenicity, 3) host-parasite relationships, including histopathology of diseased conifers and the role of toxins from bacteria-nematode ecto-symbionts, 4) pwn life cycle and transmission, 5) b. xylophilus dissemination models, 6) associations (with other nematodes), 7) diagnostics, 8) quarantine and control of the pwn and 9) biocontrol of the pwn. keywords review, a brief survey of research on pine wilt disease www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 27 published by scholink inc. 1. introduction pine wilt disease (pwd), caused by the pinewood nematode (pwn) bursaphelenchus xylophilus, causes significant losses in coniferous forests in eastern asia, including japan, china, and south korea (zhao, 2008, pp. 264-274) as well as western europe, including portugal (mota & vieira, 2008). as a result, the pwn is one of the most important pests on many countries' quarantine lists around the world. an international pinewood disease symposium was organised in nanjing forestry university on july 20-23, 2009, under the auspices of the international union of forest study organizations (iufro), as a result of the relevance of pwd and ongoing research on the topic. this symposium included over 130 researchers from 12 nations, who presented their most recent research findings on both the pathogen and pwd. we evaluate the most recent research on the issues covered in the symposium, as well as other relevant papers, such as surveys being conducted in different countries, pwd pathogenicity, pwn taxonomy, and pine wilt control. longhorn beetles of the genus monochamus vector the pwn’s juvenile transmissive stage. the pwn interacts with a variety of wood-inhabiting microorganisms during its life cycle, including fungus on which it feeds and reproduces, as well as ecto-symbiotic bacteria from the genus pseudomonas. pwns eat on plant tissue in living trees and the mycelium of xylobiotic fungi in dead trees, and they live in resin channels within the wood. the pwn was introduced into southwestern europe from east asia in the 1990s, causing significant forest damage (mota, braasch, bravo, penas, burgermeister, metge & sousa, 1999, pp. 727-734). because of the devastating pan-european spread of pine wilt disease in portugal, the national eradication program to control the pinewood nematode (prolunp) was established to develop protocols for controlling the pwn, as existing eu measures were ineffective (rodrigues & sousa, 2009, p. 23; rodrigues, 2008, pp. 5-14). as a result of global warming, the pwn may invade russia and parts of central and northern europe. this, combined with the possibility of hybridization between the harmful species b. xylophilus and the widely distributed but weakly pathogenic b. mucronatus, could result in new pathogenic races, as seen in japan (togashi, kasuga & matsunaga, 2009, pp. 38-39). 2. fundamental conceptions of pwd development pwd is thought to be caused by the interaction of three factors, including the presence of: 1) a susceptible pine host whose death is a prerequisite for vector beetle oviposition, 2) specific fungi upon which the pwns feed and multiply, and 3) certain mycorhizas, which together promote plant immunity and water uptake, both of which decrease host mortality while favouring pwd spread, according to various studies (futai, 1997, pp. 171-181; futai, 2008, pp. 5-12). zhao (zhao & lin, 2005, pp. 339-345; zhao, 2009, pp. 14-19) believes that a combination of these two factors, namely 1) b. xylophilus nematodes and 2) bacteria of the pseudomonas fluorescens species group (these bacteria are ecto-symbyonts on the nematode’s mucous body sheath), is required for pwd development. in an www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 28 published by scholink inc. infected tree, as well as on pine callus tissue, nematodes and bacteria boost each other’s multiplication. pwn proliferation is stimulated, dna is destroyed, and pine phloem cells are killed by a protein that is similar to the flagellin of p. fluorescens. the mucous body sheath extract reduces the plant’s immunological response and promotes pseudomonas proliferation. when bacteria from b. xylophilus species are added to plant tissue cultures, axenic b. mucronatus nematodes (non-pathogenic species of the b. xylophilus group) become pathogenic, whereas surface-sterilized bursaphelenchus nematodes do not cause wilt symptoms. because dying trees attract the beetle that vectors the nematodes and associated ecto-symbiotic bacteria, tree death (i.e., death caused by pwd) is an essential condition for the pwn-pseudomonas life cycle to be completed. 3. pathogenicity only the japanese strain was harmful to cedrous deodara in a pathogenicity test with two pwn isolates from china and japan, although both isolates were pathogenic to pinus thundergii and pinus massoniana (han, ben & zheng, 2009c, p. 57). pinus k.comoraiensis and larix olgensis seedlings were destroyed by the b. mucronatus isolate (bmrfe) from pinus koraiensis (russian far east), however pinus sylvestris and pinus densiflora seedlings survived. furthermore, only the french strain of b. mucronatus induced p. sylvestris to wilt out of two b. mucronatus isolates (kulinich, zhao & kozyreva, 2010, pp. 153-154). three b. mucronatus isolates from different parts of russia were studied (grant rfbr 100401644), and it was discovered that b. mucronatus (bmrfe) harboured the most phytotoxic bacterium (zhao, 2009, pp. 14-19). the authors investigated (figure 1) the possibility of invasive species b. xylophilus genetic introgression into native populations of b. mucronatus (bm) and its impact on pathogenicity (togashi, kasuga & matsunaga, 2009, pp. 38-39). the f1 bm pwn males were backcrossed with virgin females from the parent populations of bm and pwn. the findings show that the virgin female is solely responsible for cytoplasmic heredity. in addition, investigations have shown that hybrids containing the nuclear pwn genome are more likely to be successful. virulent to p. thunbergii and have a higher population in plant tissue, the nuclear bm hybrids outperformed the nuclear bm hybrids, whereas for the purposes of this study, cytoplasm heredity was irrelevant pathogenicity. two pwn isolates were used in different tests. three inbred lines were used to create the inbred lines. for p. thunbergii, two were virulent and two were avirulent. the results revealed that the virulence features of all lines differed from each other and from the parent isolates (the gene). aflp was used to discover pathogenicity indicators); on cultures, pathogenic lines had low multiplication rates. botrytis is a fungus (ichimura, shinya, takemoto, takeuchi & futai, 2009, p. 55). pathogenicity is determined by the nematode’s ectosymbionts rather than the nematode’s multiplication rate on the fungus. also, if the inoculum consists of pwn cultivated for many generations on botrytis or if pine seedlings are inoculated with transmissive pwn juveniles from beetles, wilt mortality rates are reduced (li, wang & moens, 2009a, p. 56). www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 29 published by scholink inc. figure 1. pine wilt disease model showing assessment of climatic and ecological parameters expression under various environmental condition 4. the histopathology of conifers and the significance of toxins from bacteria-nematode ectosymbionts in host-parasite relationships a histological analysis of 1-year p. thunbergii seedlings revealed that the nematode migrates slowly and only downward during the early stages of wilt disease development; however, as the population grows, nematode movement accelerates and becomes bidirectional (up and down). the cambium, then the cortex, phloem, and xylem parenchyma, show necrotic brown colour and tissue deterioration as the wilt progresses. in susceptible pine variants, this is followed by an initial increase in the water potential of the plant cells, which then decreases and then increases again; however, in susceptible pine varieties, all of these activities occur 2 days earlier than in resistant pine species (su & ye, 2009, pp. 78-79). the quantity of pwns and bacteria increases throughout pwd growth, particularly p. fluorescens, pantoea sp., and sphimgomenas pancimobilis (xie & zhao, 2009, p. 58). pwn and bacteria have been linked in two ways, both of which are related to pwn presence in wood samples: endophytic and true nematode bacterial partners (actinobacteria and firmicutes), and endophytic bacteria janthinobacterium agaricidamnosum and dyella yeojuens (santos, proenca, fonseca & morais, 2009, p. 37). www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 30 published by scholink inc. such bacterial symbionts are connected to pwns via a protein and carbohydrate-rich surface coating found on all parasitic and invasive stages of the pwn (shinya, takeuchi, hironobu, ueda & futai, 2009, p. 52). the body surface of the worms must first be surface sterilised before examining the involvement of such bacteria in pwd pathogenicity. the following is a list of the efficacy of several sterilisation solutions, in order of effectiveness: >0.1 percent mercuric chloride >4 percent sodium hypochlorite >3 percent hydrogen peroxide the optimal treatment time is 25 minutes at 25 degrees celsius, which produces axenic nematodes. longer nematode treatment times result in higher nematode mortality (zhang & zhao, 2009, pp. 59-60). using axenic callus tissue collected from mature p. thunbergii embryos, protocols have been established to assess the involvement of pwn and bacterium interactions in pwd formation. such tissue is grown in the dark on a culture medium containing the required hormones. the cell browning response does not occur under these conditions (gao & zhao, 2009, p. 83). it is possible to test the harmful effects of bacterial secretions on pine cells using this approach. as a result, it has been demonstrated that a cell-free filtrate obtained from the growth of a p. fluorescens strain isolated from pwns is multi-component, containing proteins and tiny organic compounds. the original non-dialyzed filtrate or the mixture of dialyzed components, rather than any single chemical, has the most harmful effect on p. thunbergii cell cultures (xu, zhao, liang & zhao, 2009b, p. 61). the p. fluorescens filtrates yielded a flagellin and two cyclic peptides, all of which cause the pine cells’ dna, nucleus, and cytoplasm to degrade, resulting in an increase in cell conductivity (li, guo, zhao & li, 2009c, p. 49). the extracellular lignin peroxidase produced by p. fluorescens bacteria isolated from pwns is involved in the biodegradation of lignin. p. thunbergii cell suspensions have been demonstrated to be toxic to this enzyme (kong, guo, zhao, & li, 2009, p. 54). furthermore, the toxic effect of bacterial filtrates has been shown to be genetically determined, with culture filtrates of two pseudomonas strains obtained using artificial mutagens being non-toxic to p. thunbergii cells (wang, zhao, jiang, ren & zuo, 2009c, p. 53). 5 the life cycle of pwn and how it is transmitted entomologists and nematologists from europe and the far east have recently discovered vital new information about the pwn-vector beetle relationship. previously, only the connections between the pwn-bursaphelenchus xylophilus and its beetle vector monochamus alternatus in asia and b. xylophilus and its vector m. caronensis in north america had been examined in depth. the beetle vector m. galloprovincialis, on the other hand, is quite abundant throughout southern europe. on pinus pinaster, it is a secondary xylobiont with a one-year life cycle. an investigation of the m. the transmission to the galloprovincialis cycle demonstrated that primarily occurs during the maturity of the conifer host tree six weeks after the adult beetle emerges) and during beetle oviposition, to a lesser extent (sousa, bonifacio & naves, 2009, pp. 42-43). juveniles in the transmission stage congregate in the beetle’s metathorax once they’ve started, they’re in the pupal chambers, there was a relationship www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 31 published by scholink inc. with a beetle. the skin of the mature callow beetle is extremely delicate (naves, bonifacio & sousa, 2009, p. 41). in a study conducted by south korean academics in 2006, the beetle m. has a symbiotic relationship with the beetle m. pine and saltuarius pinus koraiensis is a species of pine native to korea. m. was found to be the winner. saltuarius beetles are vectors of pwn transmissive juveniles. bursaphelenchus mucronatus and bursaphelenchus mucronatus (european type) han and colleagues (han, koh, han, chung & shin, 2009b, p. 81). b. xylophilus is attracted to wood that has already been afflicted with nematodes, according to research on pwn migration. the fungal infection when compared to other fungus, botrytis cinerea, which is used to raise pwn in the lab, is the most appealing. while the non-fractioned extract’s attraction impact is bigger than any of its fractions (pan & long, 2009, p. 71). pwn transfer from roots to a 7-year-old pine (2009). seedlings have been observed and confirmed by pwns are found in the roots of native forest plants (yil-sung, hyang-mi & hei-soon, 2009, p. 80). 6. models of bursaphelenchus xylophilus dispersal at the nanjing symposium, several talks focused on simulation modelling of pwn’s past spread and loss forecasts from pwd. for the evolution of the genus bursaphelenchus, ryss (2009) devised an allopatric model. according to the model, 1) the genus b. xylophilus arose in the north of the paleocontinent pangea, 2) the b. xylophilus species group arose in east asia, and 3) b. xylophilus arose in the american continent and was later returned to the initial area of its species group, namely east asia, via an anthropogenic mode. the order aphelenchida as a whole is thought to have originated in the gondwana paleocontinent (as evidenced by the locations of the most basic taxa within the order), and that the aphelenchids then travelled north in pangea. anhydrobiotic and entomophilic stages evolved into various lines of aphelenchids throughout the historic spread to the north. pwn distribution models in china (wang, 2009a, pp. 45-46) are based on pwn occurrence records, particularly in economically important regions in the yangtze and pearl river drainage zones. the latter leads to the conclusion that pwd diffusion in china is primarily due to internal and international trade. for forest plantations in a group of chinese provinces, mathematical prognostic models on pwn distribution were constructed. elevation, annual precipitation, precipitation seasonality, annual temperature range, tree height, and crown diameter are all used in these models (li, ju & wu, 2009b, p. 47; shi, luo, wu, yai, chen & jiang, 2009, p. 44). www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 32 published by scholink inc. 7. associations a survey of the pines pinus massoniana, pinus thunbergii, pinus elliottii, pinus densifl ora, and pinus armendii revealed that the pwn b. xylophilus co-inhabits with 10 other nematode species for the dominant species: b. mucronatus, b. aberrans, b. hofmanni, b. sp., aphelenchoides macronucle (negi & ye, 2009, p. 84). the aphelenchoides nematodes from the japanese black pine, p. thunbergii, are characterised as a new species with molecular and morphological differences from a. macronucleatus (cheng, hao & lin, 2009, p. 35). the occurrence of morphologically and taxonomically identical aphelenchid species and genera highlights the need for molecular diagnostics for pwn. 8. diagnostics compared morphological and molecular data to determine bursaphelenchus species identity, establishing 13 species groups based on six morphological characteristics and creating an illustrated tabular key using the most important morphological characteristics such as the number of lateral fields incisures, male caudal papillae patterns, and male spicule shapes. seventy-three of the nominal bursaphelenchus species were successfully categorised, whereas twenty-four were not. for 39 species, a phylogenetic ssu r-dna tree is provided (braasch, gu & burgermeister, 2009, p. 73). other presentations in nanjing focused on the pwn’s molecular diagnostics. in south korea, 15 bursaphelenchus isolates were analysed using pcrits and d2d3 rdna (sequencing and rflp), resulting in the identification of bursaphelenchus xylophilus, b. mucronatus (european subspecies on pinus koraiensis and asiatic subspecies on pinus thunbergii), p. tusciae, p. lini, p. because of the unique zipcode that hybridises on the carrier with oligonucleotides-primers and thus eliminates the accumulation of inhibitors of the pcr process (ge, li, liu & chen, 2009, p. 32) developed a padlock probe and hrca technique to identify pwns; the technique detection sensitivity was 10 times higher than that of conventional pcr. because of its simplicity, a new diagnostic approach based on isothermal specific amplification of pwn dna taken directly from tiny wood chips (aikawa, kanzaki & kikuchi, 2009, p. 34) is anticipated to become common in the future. another presentation at the nanjing meeting focused on another easy express approach for identifying the early stages of the pwn by revealing cellulase activity using a colour reagent. the premise for this approach is that dead wood containing b. mucronatus turns white, and real-time fluorescent molecular diagnostics (atf-pcr its-2) are employed to validate pwn identification (wang, 2009b, pp. 25-26). 9. control and quarantine of the pwn quarantine methods contain a set of detection and control strategies for pwn, as well as approaches for specialist timber treatment. pwd is a standard process used in quarantine work. epidemiological surveys, pwn diagnostics, and beetle plotting traps, vertical wood traps, and the disposal of dying animal’s branches on damaged trees or dead and dying trees, nematode-infested lumber fumigation, and biological control command (huang, tang, chen, kang, he & yang, 2009, p. 67). using aerial www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 33 published by scholink inc. photography is also a viable option. near-infrared colour film photography enables for pwd-affected plants can be identified by their leaves. discolouration. the original recognises the latter. infected trees can be recognised using gis software. using a palmtop computer with a built-in camera receiver for gps (nakamura, takehana, itagaki, tashiro, ohta & nakakita, 2009, p. 33). the european union’s (eu) action plan for pwd calls for the creation of a three-kilometer-wide clear-cut zone encircled by a six-kilometer quarantine zone surrounding the affected area. only after rigorous treatment and control can logs from the quarantine zone be transported out of the zone. in addition, the quarantine zone must be maintained for a period of 15 years following the last pwn report (hannunen, tomminen, poutt & kukkonen, 2009, p. 77). cutting, burning, or fumigation of wood, limits on transporting wood from infested areas, and a mandatory 3-year control in areas where the pwn has been identified before the territory can be proclaimed a “clean area” are all part of south korea’s post-pwd management plans after detection (hannunen, tomminen, poutt & kukkonen, 2009, p. 77). heat treatment, methylbromide fumigation, and removal and burning of infected trees are the three forms of quarantine treatments used in the eu. because to methyl bromide limits (due to environmental concerns), three alternative chemicals are now recommended: the fumigant sulphur fluoride, the trunk-injection drugs milbemectin, and emamectine benzoate (shin, moon & han, 2009, p. 22). for wood goods and wood packaging material destined for international trade, the international plant protection convention (ippc) mandates a 30-minute heat treatment at 56°c (wood core temperature) (trindade & cerejeira, 2009, p. 85). because both conventional and real-time pcr rely on the detection of dna, they are unable to distinguish between dead and live pwns. as a result, a new reverse transcriptase pcr assay based on the utilisation of the heat shock protein 70 a mrna as a viability marker has been created to evaluate the heat treatment efficiency. this marker degrades rapidly in dead pwns in comparison to stable dna (allen, 2009, p. 24). 10. the pwn’s biocontrol the vector beetles, pwns, or their ectosymbiotic bacteria can all be targets for biocontrol. the pwn vector monochamus alternatus has been infected with a pathogenic strain of the entomophilic fungus metarhizium, which was originally obtained from the ichneumon scleroderma. mass release of the fungus carried on laboratory reared scleroderma provides effective biocontrol in areas with severe pwd (xu, pan, liu & han, 2009a, p. 66). under field conditions in china the release of \sscleroderma guani (natural enemy of monochamus \sbeetles) near pwd-affected trees leads to a 20 percent parasitism rate of the vector beetle m. alternatus (tang, kang, liang, chen, huang, chen, chen, yang & he, 2009, p. 68). the regular release of radiation-treated monochamus alternatus males into pwn-infested forests can effectively reduce the number of beetles; for example, after six years of regular release, the results are comparable to those obtained using chemical control against monochamus, but at a much lower cost (zhang, ma, wen, qu & hou, 2009, p. 69). www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 34 published by scholink inc. in addition, wood-rotting fungus and certain plant compounds can be employed to combat the pwn. a search was conducted in china for a fungus that effectively decomposes the stumps of pwd-killed pinus massoniana trees. one stipulation for such fungi is that they cannot be used as food by the pwn. for testing, a strain of the fungus laetiporus sulphureus was chosen (wang, chen, li, piao, shin & chung, 2009b, p. 82). the fraction with the highest antinematode activity was isolated by high-speed countercurrent chromatography (hsccc) from five strains of the actinomycete streptomyces with nematicide filtrates (jiang, zhao, wang & zuo, 2009, p. 65). in south korea, the hypomycete esteya vermicola is the first endoparasitic fungus recovered from fungus-infected pwn. the fungus’s sticky lunate conidia connect to the nematode cuticle during its life cycle, and the mycelia penetrate and eat the nematode’s body. during the next infection cycle, esteya vermicola produces fresh conidia, which infect intact nematodes. several aggressive esteya strains were isolated, all of which killed pwn isolates in 4 to 5 days (wang, fang, wang & sung, 2009a, p. 64). using a commercial biocontrol agent containing esteya strains against the pwn and several application methods (suspension spraying, trunk injection into trees, and applying infected nematodes onto trees), researchers found that e. vermicola could help pine trees survive pwn infection in greenhouse and field tests (sung, fang, wang & wang, 2009, p. 63). to manage pwd in portugal, oil components from several aromatic plants were studied, and four of 27 oils were identified as anti-pwn. at 1 mg ml, their nematicidal activity was thymbra capitata > thymus caespititius > satureja montana and > cymbopogum citratus in order of efficiency. carvacrol and geranial were discovered to be nematicidal compounds (vieira, barbosa, lima, dias, tinoco, pedro, figueiredo, barrosa & mota, 2009, p. 76). the strong nematicidal activity of cynanchum komarovii extracts has been determined in china, and the activity has been linked to succinate dehydrogenase inhibition in the pwn (yang & liu, 2009, p. 70). the strong efficacy of oxolinic acid against five bacterial strains isolated from the pwn has been identified in laboratory experiments employing six antibiotics. after injecting 3-mg oxolinic acid into 3-year-old seedlings, pine wilt symptoms in p. densiflora decreased by 70%. a mixture of oxolinic acid and the nematicidal agent abamectin showed better disease control of pwd in field experiments with 20-year-old pines than either oxolinic acid or abamectin alone (kim, kwon, choi, choi, jang, park, sung, kang, moon & lee, 2009, p. 75). pwd control has been proposed in hunan province, china, using local p. densiflora seedlings. the second generation of resistant and susceptible pine clones hybrids that survived the experiments show increased resistance to pwn and a significant reduction in pwn-induced mortality. the international symposium in nanjing outlined the essential concepts of parasite-caused conifer wilt, including newly collected knowledge on the function of symbionts and pwn vectors in the disease’s pathogenesis and transmission. biocontrol and contemporary quarantine tactics are examples of new technology tools in diagnostics and pest control. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 35 published by scholink inc. 11. conclusion we have successfully developed a numerical scheme known as (nsfdm) for the consider model. through the mentioned method, we have computed the solution of the proposed model for different values of n, m. hence (nsfdm) will excellently use in future for dealing non complicated problems. pine wilt disease (pwd), caused by the pinewood nematode (pwn) bursaphelenchus xylophilus, causes significant losses in coniferous forests in eastern asia, including japan, china, and south korea, as well as western europe, including portugal. the results of the research papers given at the international symposium on pine wilt disease (iufro working party meeting 4.04.03) in nanjing, china, in july 2009 are summarized in this article. the basic themes discussed included pine wilt disease (pwd), the pinewood nematode (pwn) bursaphelenchus xylophilus, and other pwn-associated microorganisms that play a significant role in pwd, such as bacteria (e.g., pseudomonas fluorescens). the majority of the papers are based on pwd-pwn research in east asia and russia. the following are some of the specific topics covered: 1) fundamental concepts of pwd development, 2) pathogenicity, 3) host-parasite relationships, including histopathology of diseased conifers and the role of toxins from bacteria-nematode ecto-symbionts, 4) pwn life cycle and transmission, 5) b. xylophilus dissemination models, 6) associations (with other nematodes), 7) diagnostics, 8) quarantine and control of the pwn and 9) biocontrol of the pwn. author contribution mr. abdul ghaffar khan, conducted this experiment, collected the data, analyze the data and wrote the manuscript, while dr. imran and ansar hussain revised and reviewed the manuscript. dr. tariq mahmood, and dr. hayat zada identified disease and pathogens of the pine wilt study under various climatic conditions. conflict of interest the authors declared that they have no any interest of conflict in publishing these findings. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 36 published by scholink inc. references aikawa, t., kanzaki, n., & kikuchi, t. 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(2009). genetic diversity in pathogenicity among isolates of the pine wood nematode, bursaphelenchus xylophilus. international symposium on pine wilt disease (p. 55). nanjing, china. https://doi.org/10.1007/bf02348216 https://doi.org/10.1007/978-4-431-75655-2_2 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 37 published by scholink inc. jiang, j. h., zhao, b. g., wang, q. q., & zuo, p. (2009). the isolation and identification of actinomycetes from soil in yunnan and inner mongolia, and their possible anti-bursphelenchus xylophilus (steiner & buhrer) activity. international symposium on pine wilt disease (p. 65). nanjing, china. kim, j. c., kwon, h. r., choi, g. j., choi, y. h., jang, k. s., park, m. s., sung, n. d., kang, m. s., moon, y. s., & lee, s. k. (2009). suppression of pine wilt disease by an antibacterial agent oxolinic acid. international symposium on pine wilt disease (p. 75). nanjing, china. kong, l. y., guo, d. s., zhao, b. g., & li, r. g. (2009). partial purification and characterization of extracellular lignin peroxidase from pseudomonas fluorescens gcm5-1a. international symposium on pine wilt disease (p. 54). nanjing, china. kulinich, o., zhao, b. g., & kozyreva, n. (2010). pathogenicity of bursaphelenchus mucronatus in russia. j nanjing forest univ., 34(2), 153-154. leal, i., cragg, g., allen, e., green, m., & rott, m. (2009). development of a new technique to detect mrna by reverse transcription and pcr as an indicator of viability in pinewood nematode. international symposium on pine wilt disease (p. 30). nanjing, china. li, h. m., wang, x., & moens, m. (2009a). pathogenicity of bursaphelenchus xylophilus from natural and in vitro sources to pinus thunbergii seedlings and saplings in nanjing, china. international symposium on pine wilt disease (p. 56). nanjing, china. li, m. y., ju, y. w., & wu, w. h. (2009b). predicting potential habitat for the pine wood nematode based on an ecological niche model. international symposium on pine wilt disease (p. 47). nanjing, china. li, s. n., guo, d. s., zhao, b. g., & li, r. g. (2009c). toxins secreted by pseudomonas fluorescens gcm5-la carried by pine wood nematode and their toxicities to japanese black pine. international symposium on pine wilt disease (p. 49). nanjing, china. mota, m. m., braasch, h., bravo, m. a., penas, a. c., burgermeister, w., metge, k., & sousa, e. (1999). first report of bursaphelenchus xylophilus in portugal and in europe. nematology, 1(7-8), 727-734. https://doi.org/10.1163/156854199508757 mota, m., & vieira, p. (2008). pine wilt disease: a word wide threat to forest ecosystems. the netherlands (i-xvii+405). springer. https://doi.org/10.1007/978-1-4020-8455-3 nakamura, k., takehana, m., itagaki, t., tashiro, h., ohta, k., & nakakita, o. (2009). detection of pine wilt-damaged trees using near-infrared color photograph. international symposium on pine wilt disease (p. 33). nanjing, china. naves, p. m., bonifacio, l., & sousa, e. (2009). interactions of the pine wood nematode bursaphelenchus xylophilus with its vector in portugal. international symposium on pine wilt disease (p. 41). nanjing, china. https://doi.org/10.1163/156854199508757 https://doi.org/10.1007/978-1-4020-8455-3 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 38 published by scholink inc. negi, s., & ye, j. r. (2009). occurrence of nematode species associated with pine wood in jiangsu, zhejiang and gansu provinces of china. international symposium on pine wilt disease (p. 84). nanjing, china. pan, c. s., & long, r. m. (2009). extraction of active components from the fungus botrytis cinerea and their attraction to the pinewood nematode bursaphelenchus xylophilus. international symposium on pine wilt disease (p. 71). nanjing, china. rodrigues, j. m. (2008). eradication program for the pinewood nematode in portugal. in m. mota, & p. vieira (eds.), pine wilt disease: a word wide threat to forest ecosystems (pp. 5-14). the netherlands: springer. https://doi.org/10.1007/978-1-4020-8455-3_1 rodrigues, j. m., & sousa, e. (2009). portuguese national action plan for pinewood nematode control: strategy, actions and results. international symposium on pine wilt disease (p. 23). nanjing, china. santos, v. d. m. c., proenca, d. a. n., fonseca, l., & morais, p. v. (2009). endophytic bacteria isolated from pine wilt affected pinus pinaster trees. international symposium on pine wilt disease (p. 37). nanjing, china. shi, j., luo, y. q., wu, h. w., yai, x. s., chen, w. p., & jiang, p. (2009). evaluation criteria and indicator system of resistance and resilience of pine forest ecosystems to bursaphelenchus xylophilus invasion. international symposium on pine wilt disease (p. 44). nanjing, china. shin, s. c., moon, i. s., & han, h. (2009). current research and management of pine wilt disease in korea. international symposium on pine wilt disease (p. 22). nanjing, china. shinya, r., takeuchi, y., hironobu, m., ueda, m., & futai, k. (2009). surface coat proteins of the pine wood nematode, bursaphelenchus xylophilus. international symposium on pine wilt disease (p. 52). nanjing, china. https://doi.org/10.1163/156854109x447006 sousa, e. m., bonifacio, l., & naves, p. (2009). general aspects of the relations between monochamus galloprovincialis (oliv.) and bursaphelenchus xylophilus (steiner & buhrer) nickle in portugal. international symposium on pine wilt disease (pp. 42-43). nanjing, china. su, s. r., & ye, j. r. (2009). dispersal of pine wood nematode in resistant pine trees and host cells response to the nematode invasion. international symposium on pine wilt disease (pp. 78-79). nanjing, china. sung, c. k., fang, z. m., wang, c. y., & wang, z. (2009). application of esteya vermicola, an endoparasitic fungus of the pinewood nematode, for controlling pine wilt disease. international symposium on pine wilt disease (p. 63). nanjing, china. tang, c. s., kang, w. t., liang, n., chen, s. q., huang, j., chen, q., chen, j. w., yang, x., & he, x. y. (2009). releasing scleroderma guani to control monochamus alternatus in the pine forest of fujian. international symposium on pine wilt disease (p. 68). nanjing, china. https://doi.org/10.1007/978-1-4020-8455-3_1 https://doi.org/10.1163/156854109x447006 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 39 published by scholink inc. togashi, k., kasuga, h., & matsunaga, k. (2009). populations originating from hybrids between bursaphelenchus xylophilus and b. mucronatus, their virulence to pinus thunbergii and boarding ability onto monochamus alternatus adults (pp. 38-39). nanjing, china. trindade, m., & cerejeira, m. j. (2009). the direct control measures against the pine wood nematode bursaphelenchus xylophilus. the portuguese case. international symposium on pine wilt disease (p. 85). nanjing, china. vieira, p., barbosa, p., lima, a. s., dias, l. s., tinoco, m. t., pedro, l. g., figueiredo, a. c., barrosa, j. g., & mota, m. (2009). nematicidal activity and composition of the essential oils from the portuguese aromatic fl ora against the pinewood nematode (bursaphelenchus xylophilus). international symposium on pine wilt disease (p. 76). nanjing, china. wang, c. y., fang, z. m., wang, z., & sung, c. k. (2009a). esteya vermicola, an endoparasitic fungus with high infectivity to pinewood nematode. international symposium on pine wilt disease (p. 64). nanjing, china. wang, h. y. (2009a). the biogeography and economic geography of the pine wood nematode in china. international symposium on pine wilt disease (pp. 45-46). nanjing, china. wang, l. f., chen, y., li, q., piao, c. g., shin, s. c., & chung, y. j. (2009b). effects of wood-rotting fungi on the population of bursaphelenchus xylophilus. international symposium on pine wilt disease (p. 82). nanjing, china. wang, m. x. (2009b). studies on risk assessment, epidemic analysis, pathogen detection and host resistance to bursaphelenchus xylophilus. international symposium on pine wilt disease (pp. 25-26). nanjing, china. wang, q. q., zhao, b. g., jiang, j. h., ren, f. z., & zuo, p. (2009c). nonvirulent strains and mutation breeding of a toxin producing pseudomonas strain carried by bursaphelenchus xylophilus. international symposium on pine wilt disease (p. 53). nanjing, china. xie, l. q., & zhao, b. g. (2009). post-inoculation population dynamics of bursaphelenchus xylophilus and associated bacteria in pine wilt disease of pinus thunbergii. international symposium on pine wilt disease (p. 58). nanjing, china. xu, f. y., pan, y. s., liu, y. p., & han, z. m. (2009a). preliminary studies on metarhizium anisopliae and its carrier, scleroderma guani, to control monochamus alternatus. international symposium on pine wilt disease (p. 66). nanjing, china. xu, m., zhao, b. g., liang, b., & zhao, l. g. (2009b). preliminary partition of the toxins of a strain of pseudomonas fluorescens associated with busaphelenchus xylophilus. international symposium on pine wilt disease (p. 61). nanjing, china. yang, j., & liu, q. (2009). the nematocidal mechanism of cynanchum komarovii, tetraena mongolica and helianthemum ordosicum. international symposium on pine wilt disease (p. 70). nanjing, china. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 3, 2022 40 published by scholink inc. yil-sung, m., hyang-mi, c., & hei-soon, h. (2009). survival in the stump and root infection of pwn, bursaphelenchus xylophilus. international symposium on pine wilt disease (p. 80). nanjing, china. zhang, j. p., & zhao, b. g. (2009). study on the selective toxicity of disinfectants to bursaphelenchus xylophilus at low temperature. international symposium on pine wilt disease (pp. 59-60). nanjing, china. zhang, y. a., ma, p. p., wen, f. y., qu, l. j., & hou, y. x. (2009). using a sterile technique to control the pest insect monochamus alternatus hope. international symposium on pine wilt disease (p. 69). nanjing, china. zhao, b. g. (2008). bacteria carried by the pine wood nematodeand their symbiotic relationship with nematode. in b. g. zhao, k. futai, j. r. sutherland, & y. takeuchi (eds.), pine wilt disease (pp. 264-274). tokyo: springer. https://doi.org/10.1007/978-4-431-75655-2_27 zhao, b. g. (2009). the role of bacteria carried by bursaphelenchus xylophilus in pine wilt disease. international symposium on pine wilt disease (pp. 14-19). nanjing, china. zhao, b. g., & lin, f. (2005). mutualistic symbiosis between bursaphelenchus xylophilus and bacteria of the genus pseudomonas. forest pathol, 35(5), 339-345. https://doi.org/10.1111/j.1439-0329.2005.00417.x https://doi.org/10.1007/978-4-431-75655-2_27 https://doi.org/10.1111/j.1439-0329.2005.00417.x energy and earth science vol. 3, no. 2, 2020 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 11 original paper waste-energy: feasibility study of watermelon (endocarp) waste as raw-material for bio-fuel prodution biose osadebe 1* , imhontu u. maureen 1 , akenzua oghosa 1 , ehigiamusoe osaro 1 , okorie christopher 1 , atsegha bildad 1 , onabe james 1 , angalapu daudeigha jonah 1 & igbinomwanhia iyeke 2 1 environmental pollution and remediation unit, national centre for energy and environment, energy commission of nigeria, benin city, edo state, nigeria 2 department of mechanical engineering, faculty of engineering, university of benin, benin city, edo state, nigeria * biose, osadebe, e-mail: bosadebe@yahoo.com received: april 30, 2020 accepted: may 15, 2020 online published: july 16, 2020 doi:10.22158/ees.v3n2p11 url: http://dx.doi.org/10.22158/ees.v3n2p11 abstract waste to energy plays an important role in fulfilling the world’s future demands. the continuous climatic change which is primarily caused by the atmospheric concentration of greenhouse gases from the continuous use of fossil fuel due to high demand of energy in our society has affected the human race negatively over the years. similarly, the improper disposal of agricultural waste (watermelon waste) in markets and environs creates pungent smell overtime and attracts harmful organisms in our environment, destroying the aesthetics of the market, therefore, making it environmentally unsafe for man. this paper therefore describes how feasible it is to produce bio-ethanol from agricultural waste with a focus on water melon. the waste was gotten from the market and processed to get the endocarp after which a locally fabricated juicing machine was utilized for extraction of the juice from the endocarp of watermelon waste. the fermentation pot housed 60 litres of juice for 5 days and laboratory test analysis was carried out during the period of fermentation, this was to monitor the progression of fermentation. the distillate produced 65.25% alcohol content with a volume of 19.5 litres. the utilization of watermelon waste for bio-ethanol production if exploited will lead to environmental sustainability, energy efficiency and waste to wealth. keywords waste to energy, fossil fuel, water melon waste and bio-ethanol www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 12 published by scholink inc. 1. introduction nowadays, the high demand for energy has become a thing of concern globally (prasad et al., 2017), and this is because of the dependence on petroleum-based fossil fuel which is exhausting and depleting very fast in the cause of meeting its continuously increasing demands (hossain et al., 2014). moreover, it has been realized that fossil energy causes greenhouse gas emissions that have negative effects on the environment. the enormous accumulation of carbon dioxide (co2) in the environment is directly responsible for global warming (naik et al., 2010). aside the negative effect of co2 on the environment and high demand for energy, there has also been issues concerning waste management. waste is simply any object whose owner does not want to take responsibility for it (palmer, 1992). waste management is the application of techniques to ensure an orderly execution of the various functions of collection, transportation, processing, treatment and disposal (www.sciencedirect.com, 2019). improper disposal of waste causes environmental pollution. this does not affect only the atmosphere but also the populace in that environment by exposing them to health challenges like dysentery, diarrhea and respiratory diseases etc. (rinkesh, 2020). the advocacy for waste to be converted to a useful resource is necessary in nigeria. bio-ethanol derived from waste, which is our focus in this study, is a renewable and environmentally friendly type of fuel produced from a renewable and sustainable energy source called biomass (mabee et al., 2005). biomass is the material derived from plants that use sunlight to grow which include plant and animal material such as wood from forests, material left over from agricultural and forestry processes, organic industrial wastes, human wastes and animal wastes (salman, 2019). bio-ethanol’s impressive characteristics such as flame speed and wide range of flammability, high octane number (108) and evaporation enthalpy gives it a higher compression ratio (cr) with a shorter burning. besides, bio-ethanol can be used as transportation fuel in various feasible ways, directly or blend with gasoline called “gasohol” (balat, 2007). in the united states of america, the most common blended bio-ethanol used is e-10 containing 10% of ethanol concentration and 90% gasoline (balat, m. & balat, h., 2009). this research study is designed not just to solve the challenges of energy demand but to also reduce/eliminate completely the ugly sites of watermelon wastes in our environment (farms, markets and residential) which will bring about a sustainable environment for all. 2. materials and methodology 2.1 area of study the study area is tenboga market square. it is located along the upper mission road in benin city of edo state nigeria. 2.2 feedstock collection watermelon waste was collected from tenboga market located at upper mission road, benin city of edo state nigeria. personal protective equipments (ppe) were employed during field work. it was recorded that 62 balls of water melon waste was collected which weighed 205kg. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 13 published by scholink inc. figure 1. heap of water melon waste 2.3 sample preparation a knife was used to collect the endocarp of the watermelon waste which weighed 108kg and a locally fabricated juicing machine was used to extract juice from the endocarp of the watermelon waste. a cloth sieve was used to further remove the chaff from the juice and a volume of 105 litres of juice was obtained. figure 2. collection of endocarp www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 14 published by scholink inc. figure 3. extracted juice from endocarp 2.4 fermentation process fermentation is an important characteristic of alcohol production. in this regard, the prepared water melon juice was fed into the tightly covered fermentation pot to ensure anaerobic digestion of the feedstock. the fermentation pot had a stirrer which helps for proper stirring of the feedstock to enable enzymes act equally on the feedstock. brewer’s yeast of 17g was added to 105 liters of the water melon juice. physicochemical analysis (ph, conductivity, sugar content, refractive index, and alcoholic content) of the feedstock was recorded during the fermentation process. 2.5 alcohol distillate the bio-ethanol plant which was fabricated by the environmental pollution and remediation unit of the national centre for energy and environment as presented in figure 4 was utilized for the distillation of ethanol from watermelon endocarp waste. laboratory test of the distillate was also carried out and recorded this was to ascertain the alcoholic content of the feedstock. figure 4. bioethanol plant distillation unit/condenser fermentation pot water drum boiler digital temperature probe tyres for mobility ethanol collection pot www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 15 published by scholink inc. the result of analysis and graphical representation of the beer (fermenting feedstock) and distillate respectively are presented below. 3. results and discussion 3.1 results table 1. physicochemical analysis of beer period ph conductivity sugar content refractive index alcoholic content day 0 5.30 26.00 8.00 36.00 bdl day 1 3.70 34.00 8.00 34.00 bdl day 2 3.30 42.00 6.40 28.00 bdl day 3 3.20 43.00 5.80 26.00 bdl day 4 3.10 44.00 5.20 24.00 bdl note. bdl: below detectable limit. table 2. laboratory test of alcohol content of each distillate distillate ph conductivity sugar content refractive index alcoholic content 1 st distillate 4.70 0.00 20.40 86.00 59.00 2 nd distillate 4.70 0.00 22.60 96.00 58.00 3 rd distillate 5.00 0.00 23.60 100.00 56.00 4 th distillate 4.80 0.00 23.20 98.00 56.00 average values 4.80 0.00 22.45 95.00 57.25 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 16 published by scholink inc. figure 5. graphical representation of the relationship between ph and days of fermentation figure. 6. graphical representation of the relationship between conductivity and days of fermentation figure 7. graphical representation of the relationship between sugar content and the fermentation days www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 17 published by scholink inc. figure 8. graphical representation of the relationship between refractive index and the fermentation days 3.2 discussion table 1 represents the fermentation analysis of the feedstock. the ph of the sample decreased from 5.30 to 3.10 (increasing acidity) from day 0 to day 4. similarly, the sugar content and refractive index of the fermenting feedstock decreases from 8.00 to 5.20 and 36.00 to 24.00 respectively from day 0 to day 4 except for the sugar content for day 1 which remained unchanged. the conductivity of the fermenting feedstock was observed to increase from 26.00 to 44.00. the inverse relationship between the fermentation days of ph, sugar content and refractive index and the direct relationship between fermentation days and conductivity certified the formation of alcohol. figures 1-4 clearly represents this direct and inverse relationship between physiochemical parameters and fermentation days. it was also observed that table 2 represents the analysis of the distillate (ethanol). it revealed the average ph of 4.80, sugar content of 22.45, refractive index of 95.00 and alcoholic content of 65.25% of the yield. this therefore implies that water melon waste is a feasible raw material for ethanol production and if exploited will compliment the energy needs of man and bring about a sustainable environment. 4. conclusion the production of bio-ethanol from water melon waste using a localized bio-ethanol plant was successful. the sugar content and alcoholic content of the end product was measured 22.45 % brix and 65.25% respectively. the environmental pollution and remediation unit, national centre for energy and environment during their recognizance visit to farms and markets in benin city observed that a lot of agricultural waste materials are generated on a daily basis which destroys the aesthetics of our markets block drainages and also affect man. this wastes which can be a useful resource if employed www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 18 published by scholink inc. will help clean up our environment and also provide clean energy for all. acknowledgement we thank the national centre for energy and environment, energy commission of nigeria for the financial support towards the completion of this project. references balat, m. (2007). global bio-fuel processing and production trends. energy, exploration and exploitation, 25(3), 195-218. https://doi.org/10.1260/014459807782009204 balat, m., & balat, h. (2009). recent trends in global production and utilization of bio-ethanol fuel. applied energy, 86(11), 2273-2282. https://doi.org/10.1016/j.apenergy.2009.03.015 hossain, z., golam, f., jaya, n. s., mohd, s. a., rosli h., & boyce, a. n. (2014). bio-ethanol production from fermentable sugar juice. hindawi publishing coporation. the scientific world journal, 2014, 1-11. https://doi.org/10.1155/2014/957102 mabee, w. e., gregg, d. j., & saddler, j. n. (2005). assessing the emerging bio refinery sector in canada. in proceeding of the 26 th symposium on biotechnology for fuels and chemicals (pp. 765-778). springer. https://doi.org/10.1007/978-1-59259-991-2_64 naik, s. n., goud, v. v., rout, p. k., & dalai, a. k. (2010). production of first and second generation biofuels: a comprehensive review. renewable and sustainable energy reviews, 14(2), 578-597. https://doi.org/10.1016/j.rser.2009.10.003 palmer, p. (1992). green product by design 4, u.s. congress office technology assessment, washington d.c. prasad, s. a., singh, & joshi, h. c. (2007). ethanol production from sweet sorghum syrup for utilization as automotive fuel in india. energy & fuels, 21(4), 2415-2420. https://doi.org/10.1021/ef060328z rinkesh, k. (2020). conserve energy future. in critical and grievous diseases caused by water pollution. retrieved from https://www.conserve-energy-future.com/critical-and-grievous-diseases-caused-by-water-pollutio n.php salman, z. (2019). an introduction to bio-energy. retrieved from https://www.cleantechloops.com/an-introduction-to-biomass-/energy waste to energy: energy from toxic of juice waste for heat and power generation. (2019). retrieved from https://www.sciencedirect.com https://doi.org/10.1260/014459807782009204 https://doi.org/10.1016/j.apenergy.2009.03.015 https://doi.org/10.1155/2014/957102 https://doi.org/10.1007/978-1-59259-991-2_64 https://doi.org/10.1016/j.rser.2009.10.003 https://doi.org/10.1021/ef060328z energy and earth science vol. 3, no. 2, 2020 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 113 original paper characterizing opportunity power in the california independent system operator (caiso) in years 2015-2017 andrew a. chien 1 1 department of computer science, university of chicago and argonne national laboratory, chicago, usa received: september 16, 2020 accepted: october 2, 2020 online published: november 10, 2020 doi:10.22158/ees.v3n2p113 url: http://dx.doi.org/10.22158/ees.v3n2p113 abstract studying the california independent system operator (caiso) day-ahead and real-time markets for the period january 2015 to december 2017, we characterize the growth of curtailment and negative-priced power from renewable generators. results show that renewable curtailment is growing rapidly, tripling to over 400 gwh from 2015-2018. negative-priced renewable power is larger and also growing rapidly, reaching 1.5 twh in 2017 for 40% cagr. resource-hours for negative pricing grew nearly 3-fold from 80,006 to 217,728 hours, with the highest single generator reaching 955 hours in 2017 or 33% of the daylight solar hours. spatially, the quantity of negative-priced power is concentrated at a few dozen renewable generators, reaching peaks of 170gwh at the largest generator. we also consider an averaged-price model (netprice) that smooths over fluctuations to estimate the usable quantities of low-priced power. results for netprice show a much larger quantity of low-priced power available than with either negative-pricing or curtailment alone. overall, these results suggest both that opportunity power is a substantial and growing resource and a number of opportunities to exploit it. keywords renewable generation, power markets, curtailment, negative prices, power grid 1. introduction aggressive renewable portfolio standards (rps), and resulting rapid growth of variable renewable generation in power grids around the world aim to reduce the carbon-emissions and other negative environmental impacts of fossil-fuels. for example, california recently adopted even more aggressive goals of 60% renewable in 2030 and 100% carbon-free power by 2045 (shoot, 2018). these ambitious goals are transforming the power generation and use landscape and pose serious power grid challenges www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 114 published by scholink inc. including ability to achieve “merit order”, efficiency, stability, and resiliency. and of course, social welfare is an important consideration. evidence of challenges include growing curtailment, negative-priced generation, and rps stagnation. curtailment occurs where the power grid is unable to accept renewable generation due to congestion, or excess generation, causes power to be discarded at the generation site europe and the united states (lew, 2013; bird, 2013) and china (gwec, 2016). and, despite programs to increase transmission capacity and employ economic dispatch, curtailed power in europe, united states, and china exceeds 50 twh per year (gwec, 2016). economic dispatch has successfully reduced curtailment, providing economic incentives (payments) and disincentives (negative payments) for generation. renewables are increasing their participation in markets by bidding their opportunity costs, increasing the ability to manage and optimize supply and demand recognizing transmission constraints. however, one result is negative-priced power generation, power purchased by the power grid at a negative price (gross, 2015; reed, 2017). in this article we use the term opportunity power (op) to describe both curtailed power and negative-priced generation as they together represent excess renewable power generation (note 1). we use the term opportunity power to capture the notion that there is an opportunity if the negative pricing can be leveraged to enable productive use of the power. recent studies examine not only increased curtailment, but also the lesser utility (capacity factor) of renewables as their fraction is increased (wiser, 2017). our prior studies characterized this opportunity power in the midcontinent independent system operator (miso) (chien, 2018). this study analyzes opportunity power in the california independent system operator (caiso) for the period january 2015 to december 2017 with the objective of characterizing the growth of curtailment and negative-priced generation to create insights that can inform strategies to both reduce their occurrence and to exploit the opportunity that this power provides for some productive use (note 2). in the period of study, caiso’s total renewable generation grew from 45 to 55 twh (caiso, 2018). our prior studies characterized stranded power in the midcontinent independent system operator (miso) (chien, 2018). we studied caiso day-ahead and real-time market bids, market prices, dispatch prices, and production for over 375 renewable generation resources. power is settled at 1 hour intervals in the day-ahead market, and dispatched at 15 and 5 minute intervals in the day-ahead and real-time markets respectively, so this data collection includes over 125 million records. we characterize negative pricing in the day-head and real-time markets and also include caiso’s reported curtailment for renewable generation (initiated in 2016). we use this information to estimate negative-priced generation. together these form an assessment of current opportunity power today and its trends of change. findings include:  negative-priced renewable power is significant and growing. day-ahead market (dam) combined with estimated real-time dispatch (rtd) show this at 1.5 twh in 2017. estimates based on dam alone approach 1 twh and rtd alone are 5 twh in 2017. these quantities www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 115 published by scholink inc. and growing at nearly 40% cagr, and are similar to miso which is 2.5x larger.  while curtailment is a smaller quantity, it also continues to increase rapidly, tripling to over 400 gwh from 2015 to 2018. and despite a pause in recent 2018 due to lower hydro generation, it is expected to resume its rapid growth in 2019 and beyond.  resource-hours in caiso for negative pricing are growing rapidly from 80,006 to over 217,728 resource-hours, and already cover all of the renewable generators. all resources are experiencing steady increase in number of hours with averages growing, a peak of 955 hours/year in 2017, a ~33% duty factor during solar hours, increasing to higher duty factors as rps levels increase. nearly all experienced >600 hours/year.  negative-priced power is several times larger than curtailed power for renewable generation; 4x based on conservative estimation (dam-rtd-scaled), more than 10x by our aggressive measure (rtd).  spatially, the quantity negative-priced power is concentrated at a few dozen renewable generators. and, using rtd-lmp measures, reach significant quantity—170 gwh at a single generator, comparable to 19mw continuous or 47mw in sunlight hours.  the duty factor negative-pricing is more dispersed across resources, with a median close to the average grown to 576 hours/year in 2017. the peak of 955 hours represents a duty factor of 11% (24 hours) or 33% (for 10 hours).  we also consider average power price models (called netprice) that have been shown to smooth over market fluctuations, increasing realistic estimates of duration and quantity of negative-priced power (chien, 2018). these price models have similar impact in caiso, and show greater quantity of negative-priced power available. in summary, opportunity power, both negative-priced and curtailment is growing rapidly. quantities are increasing at more than 40% per year, and duty factors rising across all renewable generators. these trends represent significant challenges for the power grid and perhaps opportunities for alternate usage. further study in this area is a worthwhile endeavor. the remainder of the paper is organized as follows. we define opportunity power and methods for computing it in section 2. curtailment in caiso is discussed in section 3. in section 4, we estimate negative-priced power, using three different models. in section 5, we combine negative-priced power and curtailment to provide an overall opportunity power assessment. in sections 6 and 7, we refine this view, using the real-time market data to examine spatial and temporal distribution of negative-priced power. in section 8, we consider usage-oriented models that look at average power pricing, exploring how they would impact the usability of the resource. in section 9, we discuss our results and compare to related work. section 10 summarizes the results of the study and suggests directions for future work. finally, in the appendix (section 11), we present several scatter plots illustrating the statistical temporal properties of opportunity power. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 116 published by scholink inc. 2. definition of opportunity power we define opportunity power as two components: 1) curtailment, the power a generator would like to generate and transmit into the power grid, but ultimately does not, and 2) negative-priced power, that which is generated and transmitted into the grid, but at a market price that is negative. that is, in effect, the generator is paying the load to take the power. 2.1 curtailed renewable generation the methodology of (caiso, 2018) computes renewable generation as the difference between forecast and actual generation for each dispatch interval. this data is publicly reported at (caiso, 2018), and is available only at the level of the entire caiso region. we plot and analyze curtailed renewable generation from several perspectives in section 3. 2.2 negative-priced power caiso employs an intricate set of markets and dispatch mechanisms to ensure reliable power to a diverse set of loads, dispatching generation and scheduling transmission. we use several methods to estimate negative-priced power. 1) dam-lmp: using the day-ahead market (dam) hourly settlements, we characterize the quantity of negative-priced power. because the dam accounts for only a portion of the power transacted by caiso, and dam negative pricing is less frequent than rtd, this is a conservative estimate. 2) rtd-lmp, rtd-np: using the real-time market (rtm or rtd) 5-minute settlements, at the resource level, for rtd-lmp, we sum the total power produced when there is a negative price (rtd price) for the interval. for rtd-np, again at the resource level, we sum the total power produced as long as the average price for that interval remains negative. we consider np0 and np5 for average price thresholds of $0/mwh and $5/mwh respectively. this is an aggressive model and likely an overestimate (note 3), but matches the methodology in (chien, 2018), allowing direct comparison to miso. 3) dam-rtd-scaled: combine the dam-lmp with an estimate of the additional negative-priced power dispatched in the real-time market, using the fraction of the power covered by rtd but not dam. this model uses the assumption that the fraction of negative-priced power in the rtd is the same as that in the dam, perhaps a conservative projection. in the above three models, we use two underlying definitions of negative-priced. the first is instantaneous (single interval) negative pricing. we call this model lmpx or locational marginal pricing with threshold of $x. analyzing detailed market and dispatch data, we can compute both caiso aggregate negative-priced power at the www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 117 published by scholink inc. resolution of dispatch intervals, and also per anonymized market participant. the second is an average price model for negative-priced power. we call this model netpriced, because it computes intervals for which the average price of power is less than d. we studied three years of caiso renewable bids, dispatch prices, and production for over 375 renewable generation resources for a three-year period. we consider negative pricing in both the day-ahead and real-time markets, calculating the transacted power for each generator. as discussed, the definition of negative-priced power varies with our lmp and np models. in caiso, power is dispatched at 1-hour intervals in the day-ahead and 5 minute intervals in the real-time market, to this data collection includes over 125 million records. 3. curtailed renewable power 3.1 system-wide seasonal characterization renewable generation bid into the market is sometimes not dispatched; it is curtailed. this is another element opportunity power beyond the negative-priced power. as shown in table 1, the quantity of renewable power curtailed has grown significantly from 2015 to 2017. this power represents a small portion of renewable generation, and an even smaller portion of the overall caiso generation. however, at 402 gigawatt-hours it represents over $12m of power (at $30/mwh), so its loss is a significant cost. we report aggregate renewable numbers, but it is worth noting that renewable curtailment in caiso is dominated by solar, at a 4.5:1 ratio to wind generation. table 1. caiso system-wide renewable curtailment, 2015-2017 year curtailed renewable power (wind + solar) increase yoy 2015 187,770 mwh 2016 308,423 mwh 64% yoy 2017 401,972 mwh 30% yoy 2018 (thru july) 317,213 mwh n.a. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 118 published by scholink inc. looking at seasonal variation in curtailment (see table 2), the largest quantity occurs in the winter (january to march) and the spring (april to june), and that quantity is has grown at an annual rate exceeding an average of 50% cagr from 2015 to 2018 (tripling). reasons for this might include greater mandatory hydropower in the winter and spring. curtailment in summer is much smaller, and while larger in the fall, it is fluctuating. in 2018, this growth has slowed due to decreased hydro generation, but it expected to resume its rapid growth in 2019 and beyond. table 2. caiso system-wide renewable curtailment, 2015-2017 year winter (mwh) increase yoy spring (mwh) increase yoy summer (mwh) increase yoy fall (mwh) increase yoy 2015 47,024 n.a. 84,453 n.a. 21,496 n.a. 34,797 2016 74,885 59% yoy 92,597 2% yoy 38,899 81% yoy 102,043 194% yoy 2017 185,116 147% yoy 142,855 54% yoy 31,329 -20% yoy 42,672 -59% yoy 2018 145,191 -22% yoy 163,309 14% yoy n.a. n.a. 3.2 caiso daily and monthly reporting caiso provides a nice graphical summary of monthly renewable curtailment on is “managing oversupply” web page. we reproduce the june 2018 version of this graph in figure 1. of course, its captures similar trends to those we have summarized above. daily reporting of curtailed renewables is also available on this site (caiso, 2018). figure 1. caiso renewable curtailment by month, january 2016 thru july 2018 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 119 published by scholink inc. 4. negative-priced power we first consider the aggregate occurrence of negative-priced power in the day-ahead and real-time markets for renewable generation, system-wide. subsequently, using the real-time market data, we characterize seasonal variations. 4.1 system-wide negative-priced power as shown in figure 2, the quantity of negative-priced power in both the day-ahead and real-time markets has grown rapidly in the period. a significant quantity of power is transacted at negative prices in the both the day-ahead and the real-time markets, indicating a growing quantity of excess renewable power. the dam negative priced power is nearly 1twh for 2017. the dam-rtd-scaled estimates of negative-priced power are significantly larger, as they reflect both the growing dam negative priced power, and a scaled portion of the rtd negative priced power. finally, the rtd-lmp negative-priced power is the largest quantity and growing rapidly. this quantity of 2.5 to over 5 terawatt-hours overestimates the power transacted at negative prices (the dam prices the majority of the power), but does reflect the net balance at real-time dispatch, and can be directly compared to studies in other iso’s. figure 2. estimates for negative-priced power from day-ahead, real-time, and a scaled estimate, caiso, 2015-017 looking at table 3, we see that all three estimates of negative-priced power have large cagr’s: >300% for dam-lmp, 49% and 102% for dam-rtd-scaled, and 35% and 54% for rtd-lmp. all of these measures are growing fast, and at terawatt-hours, these are large quantities of power. the rtd-lmp negative-priced power represents a significant fraction of total renewable generation in the caiso region and is now a magnitude that is comparable to the negative-priced power documented in the miso region (6 twh in 2013 increasing to over 7 twh in 2016 (chien, 2018)). the growth www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 120 published by scholink inc. observed from 2015-17, if extrapolated, suggests a doubling period of 2 years that if realized would produce in excess of 10 twh of negative-priced power in the real-time market. this quantity would be far larger than that occurring in miso, and larger as a fraction of total power delivered by more than 2.5x. table 3. caiso system-wide negative-priced renewable generation, 2015-2017 year dam-l mp (mwh) dam-rt d-scaled (mwh) yoy rtd-lmp (mwh) yoy total renewables dam (mwh) total renewables rtd (mwh) fraction total renewables 2015 48,655 539,271 n.a. 2,512,571 n.a. 20,377,783 25,322,336 9.9% 2016 213,952 801,911 49% 3,879,929 54% 26,770,145 31,551,400 12.3% 2017 945,791 1,626,848 102% 5,263,853 35% 32,686,789 37,544,424 14.0% 4.2 real-time dispatch (rtd-lmp) seasonal characterization study of negative-priced generation using rtd-lmp across seasons is shown table 4 and figure 3. the largest quantities occur in the winter (january thru march) and spring (april thru june) seasons, with those seasons accounting for 44% and 37% of the annual quantities respectively. increase in these seasons has been rapid and continued, but fluctuating, perhaps due to changes in mandatory generation due to runoff requirements in hydroelectric generation. however, while those fluctuations may mask the trend, they present no mechanistic argument for changing it. the winter 2017 negative-priced generation corresponds to 25.5 gwh/day, a 24-hour rate of 1.06 gw, but if over the solar generation hours, closer to 2.6 gw. in summer and fall, negative-priced generation is much smaller, due to higher loads, but still significant, 5.5 gwh/day, with corresponding 24-hour rates of 0.23 gw, and solar generation hours of 0.55 gw. table 4. caiso system-wide negative-priced renewable generation (rtd-lmp), by season, 2015-2017 year winter (mwh) increase yoy spring (mwh) increase yoy summer (mwh) increase yoy fall (mwh) increase yoy 2015 656,484 n.a. 1,294,340 n.a. 224,489 n.a. 336,677 2016 962,276 47% yoy 1,273,677 (-2%) yoy 468,794 109% yoy 975,180 190% yoy 2017 2,316,267 140% yoy 1,964,827 54% yoy 535,722 14% yoy 447,037 -55% yoy www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 121 published by scholink inc. figure 3. seasonal growth of negative-priced power (rtd-lmp), caiso 2015-2017 4.3 daily variation of caiso system-wide negative-priced renewable generation aggregate statistics cannot capture the variation in generation and load that create negative-priced power in power markets. such variation is a principal challenge in efforts to reduce negative-priced generation through better planning and management, as well as to efforts that seek to exploit it as a resource (kim, 2017),(yang, 2016), (yang, 2017). we present temporal graphs of the daily quantities of negative-priced generation in the miso region and basic statistics that highlight its variability. figures 4, 5, and 6 plot magnitudes of negative-priced power occurrences, on an irregular x-axis scale of 5-minute intervals (bears no fixed relationship to time as the many 0-value data points have been omitted). and while the overall quantity of negative-priced power has grown yoy, there is a striking drop in the magnitude of events from 2015 to 2016. presumably, this reflects some improvements in the markets (forecasting, dispatch, etc.). all three of the figures show that negative-priced power varies widely in quantity and seasonally. in all three years, the january-june period accounts for significantly more than half of the x-axis, and the smaller magnitude of events in the summer is striking—though a significant number of events are still occurring. likewise the fall seems to have smaller magnitude and fewer occurrences of negative-priced generation. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 122 published by scholink inc. figure 4. daily negative-priced power (mwh) in the caiso real-time market, 2015 figure 5. daily negative-priced power (mwh) in the caiso real-time market, 2016 figure 6. daily negative-priced power (mwh) in the caiso real-time market, 2017 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 123 published by scholink inc. 5. opportunity power (curtailed and negative-priced) opportunity power comprises two components—curtailed and negative-priced generation. we have examined both, and here we combine them to gain perspective for relative impact. as shown in figures 7 and 8 as well as table 5, both curtailment and negative priced power are growing rapidly within caiso. in figure 7 shows that rtd-lmp is far larger than curtailment (13x), but is perhaps an overestimate of negative priced power. however, dam-rtd-scaled is a more conservative estimate of negative priced power, and is still 3-4x larger than curtailment. this is also consistent with studies of the miso real-time markets (chien, 2018). figure 7. opportunity power=curtailment+negative-priced for rtd-lmp, caiso, 2015-2017 figure 8. opportunity power=curtailment+negative-priced for the dam-rtd-scaled model, caiso, 2015-2017 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 124 published by scholink inc. in table 5, we summarize several estimates of opportunity power, and compare them to curtailment data. note that all are growing rapidly, and the ratios for dam-rtd-scaled/curtailed have recently increased significantly. the rtd-lmp/curtailed ratio is remarkably stable. with the rapid growth all are large quantities of power, with 2017 dam-rtd-scaled reaching more than 1.6 terawatt-hours. table 5. opportunity power by type, caiso, 2015-2017 year dam-rtd -scaled (mwh) increase yoy dam-rtdscaled/ curtailed rtd-lm p (mwh) increase yoy curtailment (mwh) increase yoy rtd-lmp /curtailed 2015 539,271 n.a. 2.9x 2,512,571 n.a. 187,770 13.4x 2016 801,911 49% 2.6x 3,879,929 54% yoy 308,423 64% 12.6x 2017 1,626,848 102% 4.0x 5,263,853 35% yoy 402,972 30% 13.1x 6. opportunity power spatial dispersion (across resources) 6.1 per resource negative-priced generation we further analyze the rtd-lmp data to characterize the experience of individual generators, computing basic summary statistics as shown in table 6. they shows that the rapid growth in caiso system negative-priced generation has already spread across all of the renewable generators, and doubling in quantity from 2015 to 2017. further, the variation across resources is large—a large multiple of the average. this is reflected in quantity of negative-priced generation at the highest power generator increasing steadily from 130 gwh to 168 gwh. note that this amount of power corresponds to 19mw (24-hour basis) or 46mw (10-hour basis) of generation. table 6. per-resource annual negative-priced renewable generation (rtd-lmp), 2015-2017 year rtd-lmp (gwh) resources average negative-priced (gwh) standard deviation (gwh) maximum negative-priced @ 1 resource (gwh) 2015 2,513 gwh 367 7 17.7 131 2016 3,880 gwh 313 12 24.5 170 2017 5,264 gwh 378 14 26.1 168 6.2 distribution across resources of negative-priced generation we examine the detailed distribution of negative-priced generation across resources to explore the magnitude of the greatest quantities of opportunity power available at a single physical location, but also to explore differences in the allocation of negative prices by the market. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 125 published by scholink inc. figure 9. annual quantity of negative-priced power per resource, caiso 2015 (sorted, largest first) we consider the year 2015 data, presenting the per-site total negative-priced power at renewable resources in figure 9. note that the maximum negative-priced power at one site was 131 gwh ($3.9m power @ $30/mwh), and all of the resources experienced negative pricing (except one!). if we compare to the average negative-priced power for 2015, 6.9 gwh/resource, we see that 68 resources exceed this average out of a total of 367. even with a large standard deviation of 17.7gwh, we see that the maximum is 7 standard deviations above the mean. and a collection of resources are well above the mean, with the top 10 accounting for 930 gwh ($27.9m). the top 20 account for 1,427 gwh ($42.8m). the top 30 account for 1,704 gwh ($51.1m). the top 50 account for 2,064 gwh ($61.9m), or over 80% of the opportunity power (2,512 gwh overall). figure 10. annual quantity of negative-priced power per resource, caiso 2016 (sorted, largest first) www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 126 published by scholink inc. we consider the year 2016 data, presenting the per-site total negative-priced power at renewable resources in figure 10. note that the maximum negative-priced power at one site was 171 gwh ($5.1m power @ $30/mwh) and all of the resources experienced negative pricing. if we compare to the average negative-priced power for 2016, 12 gwh/resource, we see that approximately 68 resources exceed this average out of a total of 313. even with a large standard deviation of 24.4 gwh, we see that the maximum is 6.5 standard deviations above the mean. and a collection of resources are well above the mean, with the top 10 accounting for 1,170 gwh ($35.1m). the top 20 account for 1,892 gwh ($56.7m). the top 30 account for 2,294 gwh ($68.8m). the top 50 account for 2,840 gwh ($85.2m), or over 73% of the opportunity power (3,880 gwh overall). figure 11. annual quantity of negative-priced power per resource, caiso 2017 (sorted, largest first) we consider the year 2017 data, presenting the per-site total negative-priced power at renewable resources in figure 11. the picture is similar to 2015 and 2016, but slightly different in degree. note that the maximum negative-priced power at one site was 168 gwh ($5.1m power @ $30/mwh), about the same as 2016. and, that again, all of the resources experienced negative pricing. if we compare to the average negative-priced power for 2017, 14 gwh/resource, we see that approximately 85 resources exceed this average out of a total of 378. even with a large standard deviation of 26 gwh, we see that the maximum is 5.9 standard deviations above the mean. and a collection of resources are well above the mean, with the top 10 accounting for 1,307 gwh ($39.2m). the top 20 accounts for 2,181 gwh ($65.4m). the top 30 accounts for 2,723 gwh ($81.7m). the top 50 accounts for 3,389 gwh ($101.7m), or over 64% of the opportunity power (5,264 gwh overall). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 127 published by scholink inc. 6.3 year to year changes (per-resource) looking at trends from 2015 to 2017, we see a dramatic increase not only in the total quantity of negative-priced power but also in its breadth of impact (resources participating). further we see that as the overall quantify of negative-priced power increases from year to year, the disparities become large for a growing number of resources (see table 7). if we look at the top-ranked resources by quantity of negative-priced power, we see significant growth in all of the top groups. we compute the average daily negative-priced generation per resource by simple dividing the total negative-priced power in the group by 365 days and by the number of resources in the group. all of these show steady growth and significant quantities of power. note that if these renewables are solar, their generation will be concentrated in the daylight hours, so the effective daylight negative-priced generation will be 2 or even 3 times larger (e.g., >150mw rate per site for top 10 in 2017). table 7. negative-priced power at the top 10, 30, and 50 resources in caiso year top 10 total (mwh) daily average @ resource (mwh) top 30 total (mwh) top 30 daily average (mwh) top 50 total (mwh) top 50 daily average (mwh) 2015 930,000 255 1,704,000 155 2,064,000 113 2016 1,170,000 321 2,294,000 209 2,840,000 156 2017 5,264,000 1,442 2,723,000 249 3,389,000 186 7. opportunity power temporal dispersion the quantity of negative-priced power is important, but its temporal distribution (all in one hour vs. spread evenly) is critical for its utility for loads. we further analyze the rtd-lmp data to characterize the experience of individual generators, “duty factor” of negative-priced power at individual generators. that is, the number of hours that each site is experiencing negative-priced dispatch, a useful measure to understand if a physically localized load could exploit the negative-priced power. we then normalize to a 24-hour window (to compare against reliable power), and also to a 10-hour window (to compare against solar generation). table 8. temporal distribution of negative-priced power occurrence at generators year total negative priced generator-hours resources average negative-priced hours / resource std deviation of negative-priced hours / resource maximum negative-priced hours / resource 2015 80,006 hours 367 218 hours 211 hours 604 hours 2016 148,675 hours 313 475 hours 183 hours 883 hours 2017 217,728 hours 378 576 hours 157 hours 955 hours www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 128 published by scholink inc. the data shows that the number of negative priced hours is growing rapidly, over 2.5-fold from 2015 to 2017. there is a large variation across resources, as shown by the large standard deviation, and the maximum hours is only 2.5x standard deviations above the mean. this is a much lower variation than we saw with quantities of negative-priced power; this difference is presumably due to different peak generation capacities. for the sites with maximum hours, the numbers are large enough to correspond to a significant duty factor, particularly for a variable renewable generator. for example, the 2015 number, 604 hours, corresponds to duty factor of 7% (vs. 24 hours), and 21% (vs solar hours). the maximum for 2016, 883 hours, corresponds to duty factor of 10% (vs. 24 hours), and 30% (vs solar hours). and finally, the maximum for 2017, 955 hours, corresponds to a duty factor of 11% (vs. 24 hours) and 33% (vs. solar hours). obviously, a generator that is receiving negative prices for 33% of its operating hours, even if it only applies to a fraction of its power, is not likely to be happy about it. on the positive side, if an opportunistic load had the goal of exploitation of the negative-priced power, 33% x 10 hours yields an availability of about 3.3 hours per day—conceivably the duty factor of an unreliable, emerging region grid. in figures 12, 13, and 14, we examine the distributions of negative-priced power hours across renewable generation resources. we first consider 2015 data, presenting the per-site total negative-priced power hours at renewable resources in figure 12. note that the maximum negative-priced hours at one site was 604 hours. about two-thirds of the renewable resources experienced negative pricing. if we compare to the average negative-priced power hours for 2015, 218 hours, we see that approximately 155 resources exceed this average out of a total of 367 resources; not far from one-half the resources, so the negative-priced hours are reasonably spread out. figure 12. negative-priced power hours by resource, caiso 2015 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 129 published by scholink inc. we next consider the year 2016 data, presenting the per-site total negative-priced power hours at renewable resources in figure 13. note that the maximum negative-priced hours at one site increased to 883 hours. 6 resources experienced >800 hours of negative pricing. the number of resources experiencing negative pricing increased, with nearly all of the renewable generators included. if we compare to the average negative-priced power hours for 2016, 475 hours, we see that approximately 198 resources exceed this average out of a total of 313 resources; a large fraction (63%). so compared to 2015, the negative-priced hours are spread over a much larger group of resources, and falling much harder (more hours). however, there is a notable spike in the maximum number of negative-priced hours with six resource suffering nearly 50% more than peers. it would be interesting to understand the market dynamic that leads to this disparity. figure 13. negative-priced power hours by resource, caiso 2016 we next consider 2017 data, presenting the per-site total negative-priced power hours at renewable resources in figure 14. note that the maximum negative-priced hours at one site increased to 955 hours. at the high-end, now 6 resources experienced >900 hours of negative pricing, and the number experiencing >800 hours has grown from 6 in 2016, to 17 in 2017. amongst this group, there is some consistency, with many of the same sites ranking high from year to year. the number of resources experiencing negative pricing increased, with nearly all of the renewable generators included. if we compare to the average negative-priced power hours for 2016, 576 hours, we see that around 250 resources exceed this average out of a total of 378 resources; a large fraction (66%). so, the negative-priced hours are being spread over a much larger group of resources, and much more hours. however, there is a notable spike in the maximum number of negative-priced hours with six resource suffering nearly 50% more than peers. it would be interesting to understand the market dynamic that leads to this disparity. compared to 2016, the notable spike at the highest levels of negative-priced www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 130 published by scholink inc. hours is less pronounced, but a small group of ~15 generators are suffering significantly higher numbers of negative-priced hours. figure 14. negative-priced power hours by resource, caiso 2017 looking across the period from 2015 to 2017, we see a steady increase in the number of negative-priced hours, as the phenomenon grows. however, in contrast to the quantity of negative-priced power, the hours of negative priced power are spread more evenly across resources. this suggests some degree of shared fate—that perhaps the increases are defined by greater durations where there is widespread negative-pricing, rather than spatially localized negative pricing. confirming this with further study should be possible. 8. usage-oriented characterization (opportunity power models) 8.1 quantity versus opportunity power model market pricing mechanisms can be prone to short-term price fluctuations as documented in (chien, 2018) with little connection to the longer term economic performance of a generator resource or long-term price of power to a load. to explore the magnitude of this effect, we apply a net price model of power cost to the rtd data, smoothing local price fluctuations by computing weighted average price of power as defined in section 2. here we compare rtd-np0 and rtd-np5 “average price” studies to our rtd-lmp studies based on instantaneous negative prices (lmp0 model) used in prior sections. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 131 published by scholink inc. table 9. model sensitivity study, negative-priced power model, 2015-2017 (rtd with various) year opportunity power model total opportunity power (mwh) intervals longest interval (hours) average length (hours) st dev (hours) total hours interval average power (mwh) interval stdev power (mwh) 2015 lmp0 2,512,571 2015 np0 3,816,788 395,917 311 0.31 2.57 124,180 9.64 107 2015 np5 4,663,958 426,667 622 0.37 3.57 157,921 10.93 142 2016 lmp0 3,879,929 2016 np0 6,018,084 362,168 165 0.64 2.4 231,384 16.6 115 2016 np5 8,178,759 473,059 169 0.68 3.2 321,486 17.3 129 2017 lmp0 5,263,853 2017 np0 7,796,664 501,693 557 0.64 2.8 320,600 15.54 99.06 2017 np5 7,941,630 706,170 557 0.64 2.6 319,698 15.83 106.49 8.2 interval statistics vs opportunity power model the quantity and duration of opportunity power in caiso exhibits sensitivity to the pricing/acquisition model used. for example, the increase in opportunity power from lmp0 to np0 varies from 50% to over 100% (see table 8). however, the increase for np0 to np5 is varied, producing a smaller increase from ~0% to 35%. the maximum interval durations for opportunity power are surprisingly long! the maximum duration for a continuous interval exceeds the daylight hours for a single day, and presumably arises from wind generation sites. changing the pricing model causes the average length of intervals to increase, but are still short as there are many short intervals. however, the growing standard deviation indicates that there are also an increasing number of longer intervals. at the far right of table 8, we present average power per interval and the standard deviation of the power. these show significant quantity and increasing standard deviation, but not much increase in average power. this suggests that only a small number of the intervals are being substantially augmented by the more aggressive pricing models. the conclusions drawn here for opportunity power in caiso in 2017 are www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 132 published by scholink inc. qualitatively similar to those in miso, where np0 yielded 30% more opportunity power over lmp0, and np5 yielded 15-20% more power than np0 over a multi-year period (chien, 2018). 9. discussion and related work the period of analysis, 2015-2017 encompasses extraordinary changes in the caiso balancing area. in the three-year period from 2015 to 2017, total renewable generation grew from 45 to 55 twh (caiso, 2018). while that is a significant increase of 22% over two years, it is clear that quantity of curtailed and negative-priced power, by all of our measures conservative to aggressive (dam-lmp, rtd-lmp, and dam-rtd-scaled) is growing much faster—in excess of 50% per year. amongst these, the moderate estimate, dam-rtd-scaled is over 1.6 twh in 2017, and projected to exceed 2 twh in 2018. the rtd-lmp measure is already proportionately larger than that seen in miso, and exceeds 5 twh in 2017. these number represent 10’s of millions to 100’s of millions of dollars of power at average caiso prices. as the quantity increases, greater duty factors are observed with a number of sites seeing large numbers of “full day” intervals of 15.5 hours of negative pricing. section 6 shows that the distribution of the quantity of opportunity power is extremely uneven across the opportunity power generators—concentrated on a small number of sites. this information should be analyzed with respect to generator capacities to see how much of this extreme imbalance can be accounted for by this, or should be attributed to other factors such as transmission congestion or bidding behavior of renewable generators. regardless, the concentration of opportunity power increases its potential for productive used if a consuming load can be geographically localized to where the opportunity power is occurring. alternatively, the concentration may suggest that an increase in transmission resources in the area is appropriate. section 7 shows a steady shift of the entire distribution of renewable generators to higher and higher duty factors of negative pricing. in 2017, the majority of renewable generators saw >600 hours of negative pricing—the equivalent of nearly two full months of 12-hour negative pricing days. this suggests that opportunity power could be useful resource for intermittent, but power-intensive activities such as fertilizer manufacture, water desalination, or perhaps bitcoin mining. a more challenging, but promising area that we are pursuing is to exploit opportunity power for networks of hyperscale cloud data centers—a rapidly growing user of electric power (kim, 2017; yang, 2016; yang, 2017; chien, 2018). opportunity power has been documented as a large, growing phenomenon in studies of curtailment in the mid-continent independent system operator (miso) where 2.2 terawatt-hours (twh), and 5.5 twh negative priced power for a total of 7.7 twh of opportunity power from wind resources (bird, 2013; lew, 2013; yang, 2016). and in china, curtailed wind power has grown to 34 twh in 2015 (gwec, 2016). around the world, as renewable generation fraction increases due to rising rps standards, opportunity power is projected to increase significantly in both wind-heavy (kim, 2017, www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 133 published by scholink inc. miso, 2018) and solar-heavy (denholm, 2016a, 2016b, e3) renewable power grids. notably, a recent department of energy summary reports documents this phenomena as a reduced capacity factor for renewables as rps above 15% to 25% (wiser, 2017). all of these studies suggest that opportunity power is of increasing quantity, making its study of increasing importance. studies that characterize opportunity power (curtailed and negative priced power) availability at a fine-grained temporal level are rare. chien and colleagues studied two and a half years of opportunity power in the midcontinent independent system operator (chien, 2018), documenting quantities, spatial and temporal distributions, and the potential impact and limitations of adding storage to increase utility of opportunity power. the miso grid has significant renewables that are predominantly wind turbines, and much of it dispersed widely in unpopulated areas, and thus often transmission constrained. further, miso generally operates at a renewable portfolio fraction below 15%, and this fraction has changed only slowly over the past few years. this situation differs significantly from caiso which has predominately solar renewables, an rps exceeding 33%, and is less transmission limited. while both the miso study and this report document that opportunity power is available in >5twh quantities on an annual basis, the relative magnitude of opportunity power in caiso is much greater—given its smaller size. both iso’s exhibit stable geographic patterns of concentration of opportunity power, both conferring a disproportionate economic impact on certain generators, but also creating a geographically localized opportunity for exploitation. the occurrence of opportunity power in the two iso’s differs in its temporal structure as well. because of the large quantities of solar power in caiso (generation largely synchronized by sunlight hours), the occurrence of opportunity power is heavily concentrated in those daylight hours, as well as in certain seasons. in contrast, miso’s wind generation is seasonal, but the occurrence of opportunity power tends to occur at night, when load is lower. progress in energy storage is promising, but the low price of power makes its large-scale deployment for time-shifting challenging and some studies suggest on energy return-on-investment (eroi) criteria, it may never make sense to store large quantities of wind power, though solar’s higher energy quotient makes it more attractive. grid-scale storage for time-shifting, rather than small quantities for peak shaving and regulation, faces significant economic challenges. caiso is a leader in this area, with a plan to deploy 1.3 gw of storage by 2024, but even this is a small fraction of the storage capacity needed to time-shift power. in fact, recent studies show that much larger quantities of storage had little net impact on opportunity power duty (chien, 2018). 10. summary and future work detailed analysis of caiso’s day-ahead and real-time markets focused on renewables shows the rapidly changing dynamics as the fraction of renewables grows to 30% and beyond. highlights include terawatt-hours of opportunity power, dominated by negative-priced power, not curtailment. the number of hours that negative pricing occurs—at all resources—is growing rapidly; however, the www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 134 published by scholink inc. quantity of opportunity power is concentrated at a few dozen generators. in 2017, nearly all of the renewable generators are experiencing close to 600 hours or more of negative pricing per year. finally, flexible power acquisition models such as “netprice” significantly increase the duty factor of opportunity power, but not as much in caiso’s solar-dominated renewables grid, when compared to miso’s wind-dominated renewables grid. the rise of negative-priced power in both markets, and the additional growth of renewable curtailment in every dimension—quantity, duty factor, fraction of generators impacted, etc. reflect significant challenges for renewable integration at high rps levels. the result is a rising tide of opportunity power. this opportunity power is a new and growing opportunity. it creates opportunities for new uses of power that can act as “compliant loads”, adaptable in time and consumption level to availability of this low cost and environmentally friendly power resource. integrating such loads into current power markets requires new innovation. while we have studied three years of caiso data, spanning a recent period of rapid change, this change is expected to continue. so study of future data, 2018 and beyond, to explore new trends, and to assess if the trends we have identified persist. to date, there are detailed published studies on opportunity power in miso and caiso (this one), and we would hope to see such studies for further iso’s, particularly those with large fractions of renewables. one area we were not able to explore is the impact of new market products for storage and distributed energy resources. those products are being designed to affect metrics used in this study, and others. study of these impacts as renewable generation continues to grow would doubtless yield valuable insights. the growing quantity of opportunity power (op) poses the natural question—how can it be exploited? we have been exploring the possibility of using it to power cloud data centers, the fastest growing source of electric power consumption in the developed world (yang, 2016, 2017). by adapting the magnitude of the computational load and its geographic distribution, the power needs of a network of cloud data centers can be used directly to consume negative priced power. if matched well, the result would include both financial savings for the cloud computing provider, but also better integration of even higher levels of renewable generation that overall reduce the carbon impact of both cloud computing and broadly the power absorbed by the power grid. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 135 published by scholink inc. acknowledgements thanks to the team at caiso, notably mark rothleder and shucheng liu for hosting my visit, and to zhu liang for invaluable help with the data. also thanks to angela glover, hong zhou, and other members of the market quality and renewable integration team for putting up with endless questions about data and how caiso markets work! thanks also to the university of chicago whose support of andrew a. chien with a sabbatical leave for time at caiso, essential to learning about myriad data systems and products, and the current and emerging operations of the caiso markets and energy imbalance markets (eim). this work was supported by in part by the national science foundation under award cmmi-1832230 references bird, l., milligan, m., & lew, d. (2013). “integrating variable renewable energy: challenges and solutions. in nrel, technical report. https://doi.org/10.2172/1097911 caiso (california independent system operator). (2018). managing oversupply. in data summaries and daily reports. retrieved from http://www.caiso.com/informed/pages/managingoversupply.aspx chien, a. a., yang, f., & zhang, c. (2018). characterizing curtailed and uneconomic renewable power in the mid-continent independent system operator. aims energy, 6(2), 376-401. https://doi.org/10.3934/energy.2018.2.376 denholm, p., & margolis, r. (2016). energy storage requirements for achieving 50% solar photovoltaic energy penetration in california. tech. rep., us department of energy, national renewable energy laboratory. https://doi.org/10.2172/1298934 denholm, p., & o’connell, m. (2016). on the path to sunshot: emerging issues and challenges in integrating high levels of solar into the electrical generation and transmission system. tech. rep., us department of energy, national renewable energy laboratory. https://doi.org/10.2172/1253978 e3, investigating a higher renewables portfolio standard in california: executive summary. (2014). tech. rep., report from energy and economics, inc. gross, d. (2015). the night they drove the price of electricity down. in slate magazine., retrieved september 18, 2015, from slate.com gwec. (2016). global wind report: annual market update. global wind energy council, tech. rep., 2016, documents curtailment around the world. kim, k., yang, f., zavala, v. m., & chien, a. a. (2017). data centers as dispatchable loads to harness stranded power. ieee transactions on sustainable energy, 8(1), 208-218. https://doi.org/10.1109/tste.2016.2593607 lew, d., bird, l., milligan, m., speer, b., wang, x., carlini, e.m., … yoh, y. (2013). wind and solar curtailment. in workshop on large-scale integration of wind power into power systems, 10. https://doi.org/10.2172/1097911 https://doi.org/10.3934/energy.2018.2.376 https://doi.org/10.2172/1298934 https://doi.org/10.2172/1253978 https://doi.org/10.1109/tste.2016.2593607 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 136 published by scholink inc. miso. (2018). the mid-continent independent system operator (miso). retrieved from https://www.misoenergy.org/ reed, s. (2017). power prices go negative in germany, a positive for energy users. in new york times, december 25, 2017. shehabi, a., smith, s., sartor, d., brown, r., herrlin, m., koomey, j., … lintner, w. (2016). united states data center energy usage report. 2016. lbnl-1005775. https://doi.org/10.2172/1372902 shoot, b. (2018). the world’s fifth-largest economy, california, just committed to 100% carbon-free power by 2045. in fortune magazine. retrieved from http://fortune.com/2018/09/10/california-governor-carbon-free-power-energy/ wiser, r. h., mills, a., seel, j., levin, t., & botterud, a. (2017). impacts of variable renewable energy on bulk power system assets, pricing, and costs. in technical report lbnl-2001082, 11/2017 2017. https://doi.org/10.2172/1411668 yang, f., & chien, a. a. (2016). zccloud: exploring wasted green power for high-performance computing. in proceedings of the international parallel and distributed processing symposium (ipdps 2016). https://doi.org/10.1109/ipdps.2016.96 yang, f., & chien, a. a. (2017). extreme scaling of supercomputing with stranded power: costs and capabilities. ieee transactions on parallel and distributed systems, 29(5), 1103-1116. https://doi.org/10.1109/tpds.2017.2782677 notes note 1. in prior research, we have referred to this opportunity power (op) as stranded power (sp) (chien, 2018; yang, 2017; yang, 2016). note 2. we are currently exploring how to couple rapidly growing networks of hyperscale cloud data centers (shehabi, 2016) to the power grid to both enhance renewable integration and reduce cloud computing’s growing carbon footprint, as well as increase the resilience of both critical infrastructures (kim, 2017; yang, 2017). note 3. this simple methodology overestimates negative-priced power by including power that may have been settled at a positive price in the day-ahead market (dam). https://doi.org/10.2172/1372902 https://doi.org/10.2172/1411668 https://doi.org/10.1109/ipdps.2016.96 https://doi.org/10.1109/tpds.2017.2782677 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 137 published by scholink inc. appendixes sample scatter plots for resources with high quantities and incidences of negative-priced power. as shown in figure 15, res_170 has maximum power of just below 10 mw, and the scatter plot shows maximum duration of opportunity power interval of nearly 14 hours. it was the highest duty factor resource in our study for 2017. figure 15. power/duration scatter plot for res_170 as shown in figure 16, res_102 has maximum power of just below 130 mw, and the scatter plot shows maximum duration of opportunity power interval of nearly 13 hours. it was the 2 nd highest duty factor resource in our study for 2017. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 138 published by scholink inc. figure 16. power/duration scatter plot for res_102 energy and earth science vol. 3, no. 1, 2020 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 59 original paper effect of nano-silica on the thermo-physical properties of the thermal eutectic (na0.6k0.4)no3 system h. i. elsaeedy 1 , a. a. s. al ahmari 2 , k. f. abd el-rahman 3* & s. taha 4 1 department of physics, faculty of science for girls, king khalid university, p. o. box 9004, abha, saudi arabia 2 department of physics, college of arts and sciences, king khalid university, p. o. box 900, mahayel asir, saudi arabia 3 department of physics, faculty of education, ain shams university, cairo, egypt 4 department of physics, faculty of science, fayoum university, fayoum, egypt * k. f. abd el-rahman, elrahman100@gmail.com received: march 28, 2020 accepted: april 9, 2020 online published: may 26, 2020 doi:10.22158/ees.v3n1p59 url: http://dx.doi.org/10.22158/ees.v3n1p59 abstract here, we investigate the effect of adding nano-silica particles on the thermo-physical properties of the (na0.6k0.4)no3 based thermal energy storage systems. five different systems tagged as m00, m01, m02, m03 and m04, with different nano-silica percentage of 0, 1, 2, 3, and 4 wt%, respectively, were prepared. various experimental techniques were employed to study the thermo-physical properties of the systems during (solid-solid) phase p1, (solid-liquid) phase p2 and (liquid-solid) phase p3, and to clarify the effect of nano-silica on the thermal energy storage efficiency during both charging and discharging processes. according to the differential scanning calorimeter (dsc) thermal analysis, it was found that the system m02 whose nano-silica addition rate of 2 wt%, has the most favorable thermal characteristics (i.e., highest specific heat and lowest enthalpy change). moreover, the addition of 2 wt% represents the optimum distribution of nano-silica inside the principal base system m00. this leads to an improvement in the porosity of the system due to the degree of homogeneity caused by the thermophoresis effect distribution, the high surface area of the nano-silica with the activity of the m00 matrix alongside the degree of the alkalinity of nano-silica. besides, the electric conductivity measurements showed that the 2wt% percentage is the optimum one for thermal energy storage systems. keywords phase change material, thermal storage, nano silica, calorimetry www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 60 published by scholink inc. 1. introduction thermal energy storage systems can be classified into sensible heat storage, latent heat storage and thermo-chemical heat storage. latent heat storage systems use the phase change materials (pcms) as thermal energy storage media, where the thermal energy is stored or released during the material phase change transition processes. phase change materials (pcm) have been widely used for the thermal storage systems due to their capability of storing and releasing large amounts of energy within a small pcm volume, a moderate temperature variation and prolong the charging and discharging period. additionally, significant attention has been given to using salts as a phase change storage media (using encapsulation and otherwise) (goswami et al., 1990, pp. 257-262; xu et al., 2015, pp. 286-307; gaosheng et al., 2018, pp. 1771-1786; hassan et al., 2019, pp. 491-523). moreover, several mixtures of alkali nitrates and nitrites have been used as a heat transfer medium because of its low cost and good compatibility with common structural materials (borul et al., 1954, pp. 233-238). the nano3-kno3 system is one of the most extensively investigated binary inorganic salt systems (voskresenskaya et al., 2017, pp. 431-437; silverman et al., 1977, pp. 1-26; kamimoto et al., 1981, pp. 319-331; kearney et al., 2003, pp. 170-176; zhang et al., 2003, pp. 441-446; berg et al., 2004, pp. 2224-2229; villada1 et al., 2014, pp. 622-625; lin et al., 2018, pp. 685-708). the pcm’s low thermal energy storage efficiency remains, however, a big challenge for researchers. the pcm’s thermal performance is positively correlated with three different parameters, the thermal conductivity coefficient, area for heat transfer, and the heat transfer temperature difference. accordingly, the thermal performance can be enhanced by; enhancing the thermal conductivity, extending the heat transfer area, and improving the uniformity of heat transfer processes (tao et al., 2018, pp. 245-259). the thermal conductivity can be enhanced by using additives with high thermal conductivity coefficient. the high thermal conductivity carbon-based, metalfillers, porous materials, and nano-particles are commonly used as additives to enhance the thermal conductivity of the pcm (lin et al., 2018, pp. 2730-2742). using of the metal-based porous material, such as metal foam enhances heat transfer by reducing the cell size leading to the large contact surface area. in this case, the scattered air within the pores expands significantly to cause the ejection restriction of the phase transformation for the pcm during the actual operation at elevated temperatures (wu et al., 2011, pp. 1371-1380). using metal fillers led to a reduced discharging time and significant weight and cost to the thermal storage systems as well (farid et al., 2004, pp. 1597-1615). in addition, corrosion could appear when using salts as pcm (joel, 2008; dorete et al., 2012, pp. 13-25; grant, 2002, pp. 1-34). also the addition of graphite to the binary thermal storage system leads to enhance the thermal conductivity coefficient and reduced the total latent heat (xiao et al., 2015, pp. 272-284; berg et al., 2004, pp. 2224-2229; xiao et al., 2014, pp. 52-58; zhao et al., 2014, pp. 272-277; lopez et al., 2010, pp. 1586-1593). for nano-enhanced pcm material, the thermal conductivity depends not only upon the nano particle’s concentration, the particle size and shape, but also on the base pcm material (chieruzzi et al., 2013, pp. 448-456; dudda et al., 2013, pp. 37-42; leong et al., 2019, pp. 18-31; jeyaseelan et al., 2019, pp. 235-242). in contrast to previous studies, www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 61 published by scholink inc. which addressed the impact of nano-particle on the thermal performance of pcm thermal storage material, the current study is devoted to investigate the effect of nano silica on both the thermal and the physical properties of the binary molten salt 0.6nano3-0.4kno3. phase change materials (pcms) based on latent heat energy storage techniques over a nearly isothermal temperature range using paraffin wax nano composite based on carbon-coated aluminum nano particles have been regarded (chen et al., 2017, pp. 12603-12609). the thermal stability of paraffin wax was improved by the shape stabilization with 10 wt% of carbon nano tubes (fredi et al., 2017, pp. 405-420). they mentioned that the modified paraffin wax is a promising strategy to meet the highly efficient thermal management system for electric vehicles. 2. method the binary salt was prepared by mixing 60% of nano3 with 40% of kno3 by weight, in its solid form; these salts nitrates are ultra-pure from aldrich company. the mixture heated up to 350 to achieve a complete melting for this mixture; the system was then cooled at room temperature. this system represents the eutectic system (na0.6k0.4)no3, and denoted in this work as m00 system. the solid binary salt was then milled to powder, and the nano-silica was dispersed into four concentrations: 1, 2, 3 and 4 wt% in the solid binary nitrate (na0.6k0.4)no3 system separately to get m0x (x=1, 2, 3, and 4%wt.) systems. the binary system and the nano-silica particles were dispersed in 20 ml of distilled water by ultrasonic mixing for 2 hours using mxbaoheng ultrasonic homogenizer fs-t series with nominal frequency of 20 khz. the solutions were stirred by the strong ultrasonic homogeneous instrument for 2 hours, afterwards, the water solutions were heated at 150 on a hot plate to fully remove the water for at least 1 hour (shin et al., 2011, pp. 1064-1070). by grinding the dried composites, samples were obtained, after the operation process for all samples, they were immediately used for thermal, electrical, structure and electron macroscopic analysis, to identify the effect of the nano-silica on the thermo-physical properties for the (na0.6k0.4)no3, which is representing the thermal storage media. 3. result 3.1 dsc measurements the dsc thermo grams measurements for m00 and m0x (x=1, 2, 3, 4 wt%) systems have been carried out during heating and cooling. the dsc measurements were performed by using shimadzu dsc-60 plus series equipment. figure 1 shows the thermo-grams for the base matrix (m00) as representative example. the figure indicates to the existence of three peaks. the first broad peak located at ≈125 co , is mainly due to the solid-solid phase transition (p1). this phase is related to the change in the specific heat (sensible heat storage) and the transition from the displacive type modified by orientation switching (bauer et al., 2010, pp. 272-278; al sharhani, 2016; hatakeyama et al., 1989, pp. 327-335). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 62 published by scholink inc. figure 1. the dsc thermo-grams for m00 system while the second endothermic peak located at ≈234 o c, is related to the melting point of the m0 system, i.e., the phase change from solid-liquid phase (p2). the third exothermic peak at ≈223 o c represents the phase change from liquid-solid phase (p3), i.e., the solidification process. the same three peaks appeared with the thermograms measurements of the samples m0x (x=1, 2, 3, 4 %wt.). the variations in the thermal parameters, such as the enthalpy, transition point, and peak position have been studied for all samples. for example, the specific heat of the sample scan be determined from the relation (hatakeyama et al., 1989, pp. 327-335): (1) where is the peak height of the sample, is the height of the standard material from the zero line of the starting of the equipment (dsc), is the mass of the standard material (al2o3), is the mass of the sample and is the specific heat of the standard material. also, the activation energy for all phases (p1, p2 and p3) at any system by using the modified kissinger equation (rysava, 1987, pp. 1015-1021): (2) where different heights corresponding to different temperatures for each peak have been obtained. the extracted data were used to plot as ln(δq) and1/t according to the equation and hence to get the activation energy. all the thermal kinetic parameters for the m0 system are shown in figure2 (a and b) as representative example. it can be easily seen that the transition temperature does not nearly change in the all phases (p1, p2 and p3) with the increasing the concentration of the nano-silica in the m0x system. these results suggest that the nano-silica inside the m0x system having a uniform distribution and a homogeneous dispersion. this leads the sio2 (nano-silica) takes part in the network structure as a network former (chieruzzi et al., 2013, pp. 448-456). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 63 published by scholink inc. the variations in entropy (δh), the peak height, the transient temperature (δt) and the transient time (δt) with the concentration of the nano-silica for all phases (p1, p2 and p3) are mainly related to the distribution effect on the interaction potential of na + and k + ions around the (no3) group in the m0x system (taha et al., 1994, pp. 217-226). for the entropy (δh) and the peak height, it is clear from the figure that there is a minimum value corresponding to concentration value x≈2% of nano-silica. this means that the m0 system at that percentage become more stable than that at any other concentration of nano-silica, due to the stability of the thermodynamics function (thirriwg, 2006, pp. 113-121). the minimum value of (δh) at this concentration (x≈2% of nano-silica) indicates that the system has a higher ordered and mechanical stability than other any concentration. 0 1 2 3 4 5 0 20 40 60 80 100 120 140 p e a k h ig h t 0 1 2 3 4 5 8 10 12 14 16 18 20 22 24 26 p2 p2 t ra n s ie n t t e m p . (o c ) p1 0 1 2 3 4 5 0 20 40 60 80 100 120 140 t ra n s ie n t t im e ( s e c ) weight oercentage 0 1 2 3 4 5 100 120 140 160 180 200 220 240 260 t ra n s it io n t e m p . (o c ) figure 2. the thermal kinetic parameters (peak height, transient temperature, transient time and transition temperature) for m0x system with different concentration of nano silica this is supported by the variation of the transient temperature (δt) and the transient time (δt), where (δt) and (δt) which does not nearly change in the concentration range 1% x for each phase (p1, p2 and p3). these results are mainly related to the introduction of the incompatible second components, like k + ion in the nano3 structure or na + ion in the kno3. the introduction of ions influenced the order kinetics in a significant way which is related to the equilibrium kinetics in the m0 system (ping et al., 2009, pp. 27-36). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 64 published by scholink inc. 0 1 2 3 4 5 0 2 4 6 8 10 a c ti v a ti o n e n e rg y ( e v ) 0 1 2 3 4 5 0 5 10 15 20 25 p3 p2 s p e c if ic h e a t (j /g .o c ) p1 0 1 2 3 4 5 0 40 80 120 160 h e a t e n th a lp y weight percentage 0 2 4 0 5 10 15 20 25 a m o u n t o f h e a t (j ) figure 3. the thermal kinetic parameters (activation energy, specific heat, heat enthalpy and amount of heat) for m0x system with different concentration of nano silica the changes in the activation energy (eg), the specific heat (cp) and the latent heat (δq) for the different phases (p1, p2 and p3) in the m01 systems are mainly related to the thermal activation process in this system. these parameters are affected by the concentration percentage of nano-silica and the variation in the strength of na + and k + ions bonds in the (na0.6k0.4)no3 (m0) system. this variation in the bonds strength plays an important role in the delocalization of charge carried inside the m0x system. the changes in the latent heat (δq) and (cp) for the phase (p1) are very small, because this phase has a rather low heat for the transformation process. however, in the two phases p2 and p3, the changes in δq and cp are greater than the phase p1, which is mainly related to the large volume variations during the transformation process. the value of the activation energy in phase (p3) is higher than the values obtained for the phase p2 and phase p1. this is because the ordered parameters in the phase p3 increase with decreasing the temperature of transformation (liquid-solid). however, the ordered parameters decrease with increasing the temperature in phase (p2) (solid-liquid) phase, i.e., higher disorder, so that the eg in phase p3 is higher than p2 and p1 phases (papon et al., 2002). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 65 published by scholink inc. the effect of the nano-silica on the thermal properties for the thermal storage m0 system could be potentially due to the large distribution of the nano-silica per unit volume. this is because the nano-particl has a small diameter and could be more effective dispersed into the salt (na0.6k0.4)no3 and give better pores system and thermal characteristic, that is mainly related to the high specific surface energy in the m0 system associated with the high surface area of the nanosilica inside the m0 matrix (chieruzzi et al., 2013, pp. 448-456). the obtained results confirmed that the rates of changes in the kinetic and thermo-physical parameters are mainly dependent on the concentration rate of nano-silica inside this system. the results confirmed that the optimum concentration for the thermal storage (na0.6k0.4)no3 system is x≈2% of nano-silica. 3.2 electrical and thermal conductivity measurements one of the most popular of the nano-silica is mainly related to its good resistance of heat and electricity, so that it has tendency to agglomerate or cluster due to the dominant intermolecular van der-waals interaction between the particles. so that the electrical and thermal conductivity of the mixed samples with nano-silica particles mainly depend on the characterization of these nanoparticles and the uniform of dispersion of the nanoparticles in the matrix [na0.6k0.4]no3 (ning et al., 2009, pp. 518-523). figure 3 shows the variation of the electrical conductivity for the system m01 as a function of the temperature. the inset shows the variation of electrical conductivity with the concentration of nano silica at certain temperature (≈125 o c). from this figure, we can see that the values of electrical conductivity increase with increase the nano-silica up to x=2%, and then it decreases with the increase of the nano-silica. this modification enhanced the electrical conduction mechanism inside the m01 system (chieruzzi et al., 2013, pp. 448-456). the increase in the electrical conductivity up to x=2%, may be related the mono dispersion of spherical nano-silica in the matrix m0 system. besides that, the increase in the rate of the reorientation process inside the m0 matrix for the k + and na + ion surrounding the no3 ion group by the effect of temperature on the m01 matrix. however, the decreasing in the electrical conductivity with the increasing of nano-silica after (x=2% wt), could be attributed to the reduction in the bond of mobility ions released by the distribution of nano-silica inside the m0 matrix. it could be also attributed to the effect of the alkalinity degree of nano-silica ratio for the m01 system. also, the nano-silica has a lower relative density than m0 system, therefore for given mass replacement from nano-silica into the m0 system consequently leads to a lower pore volume, due to the size of the nano-silica particles. beside that the nano-silica is not a good conductor for the electrical properties (kumar, 2008, pp. 684-687). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 66 published by scholink inc. 110 115 120 125 130 0.00 0.02 0.04 0.06 0.08 0.10 1 2 3 4 0.00 0.01 0.02 0.03 0.04 0.05 c o n d u c ti v it y , ( .c m -1 ) nano silica % 0.2 % 0.4 % 0.1 % e le c tr ic a l c o n d u c ti v it y (  .c m -1 ) temperature ( o c) 0.3 % figure 4. the variation of electrical conductivity with temperature for different nano-silica concentrations in the solid-solid phase the activation energies of the m0x crystal systems are calculated according to the well-known exponential relation (rysava, 1987, pp. 1015-1021). the dependence of activation energy on the concentration of nano-silica is shown in figure 4. it is clear from the figure that there is a minimum value at x=2% nano silica. the variation of activation energy is mainly related to the lattice thermal vibration and the formation of polarizabillity arising from the cationic na + and k + ions around the (no3) group (taha, 1989, pp. 341-354). this process is mainly affected by the temperature of the system and the rate of concentration of nano-silica inside the m0 matrix system. the modification of activation energy (eg) by the presence of nano silica can be attributed to the appearance of different polaronic and defect levels in the structure of the m01 system (papon et al., 2002). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 67 published by scholink inc. 1 2 3 4 0.30 0.32 0.34 0.36 e g , (e v ) concentration figure 5. the variation of activation energy eg with different concentrations of nano silica in the solid-solid phase the thermal conductivity (k) for them0x systems was calculated from the analysis of the dsc thermo-gram curve for the phase p1 and during heating by using the following relation: (3) where q is the heat flow, l is the thickness, a is the area, (th-tl) is the difference between high and low temperature. the variation of the thermal conductivity k of the m0 and m01 systems with the concentration of the nano-silica is shown in figure 5. it is clear from the figure that thermal the conductivity decreases with the increasing of concentration of the nano-silica and then it reaches a nearly constant value starting at x=2% of nano silica. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 68 published by scholink inc. 0 1 2 3 4 0 2 4 6 8 10 12 t h e rm a l c o n d u c ti v it y , k ( w /c m .o c ) concentration figure 6. the variation of thermal conductivity with different concentration of nano-silica for m01 system in the solid-solid phase this indicates that the presence of nano silica increases the thermal resistance to the thermal fluctuations process (kumar, 2008, pp. 684-687). it can be said also that the stability of thermal conductivity starting at x=2%. this is because the decreasing for the thermal fluctuations leads to decrease in the free energy, i.e., the system become thermally stable (kumar, 2008, pp. 684-687). 4. conclusion the additive nano-silica to the eutectic (na0.6k0.4)no3 system bring a new and good additional physical properties to the thermal storage materials, which reasonable to improve the thermal charge and discharge heat energy during the phase changes transformation process. it has been found that the optimum conditions for this additive are satisfied at 2% wt for nano-silica nano-silicais characterizes by high mechanically stability and act as insulator for heat and electricity. the variation in the thermo-physical properties (cp, ∆h, ∆q, and peak height) for each phase (p1, p2 and p3) are mainly related to the effect of the nano-silica. it causes also an enhancement in the thermal properties, which is the aim from this work. the thermal analysis measurements indicated that nano-silica has no effect on the transition temperature (tr), which is mainly related to the high stability of solid-solid phase (p1), due to the kinetic hindrance of the disphasic region (na k) around the (no3) group in the m0 system. the effect of the nano-silica on the thermal storage media (m0) matrix is mainly related to the reflected modification of the electronic structure of this material. this considerable variation can be attributed to the appearance of different polaronic and defect levels. it has been found that the system m02 whose www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 69 published by scholink inc. nano-silica addition rate of 2 wt%, has the most favorable thermal characteristics. this leads to an improvement in the porosity of the system due to the degree of homogeneity caused by the thermophoresis effect distribution. the distribution of the nano-silica in the m0 system (thermophoresis effect) makes changes in the porous ratio, due to the high specific area of the nano-silica. this change in the porous system leading to effect on the performance of heating and cooling cycle, beside the rate of melting and freezing for this system. references al sharhani, m. a. s. 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(2014). development of highly conductive kno3/nano3 composite for tes (thermal energy storage). energy, 70, 272-277. https://doi.org/10.1016/j.energy.2014.03.127 https://doi.org/10.1016/j.solener.2011.03.021 https://doi.org/10.1016/j.tca.2014.04.021 https://doi.org/10.1016/j.enconman.2015.07.074 https://doi.org/10.1016/j.apenergy.2015.09.016 https://doi.org/10.1361/105497103770330091 https://doi.org/10.1016/j.energy.2014.03.127 energy and earth science vol. 4, no. 1, 2021 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 original paper measurement of surface area concentration of fine particulate matter in indoor environments pramod pai 1 1 department of physics, pes institute of technology and management, shivamogga, india received: november 2, 2020 accepted: november 30, 2020 online published: january 31, 2021 doi:10.22158/ees.v4n1p1 url: http://dx.doi.org/10.22158/ees.v4n1p1 abstract indoor exposure to fine particles (0.01-2.5 µm) is measured in the present study using surface area concentration (sac) metric for two indoor environment categories based on the cooking fuel used—kerosene and liquid petroleum gas lpg. study of sac is very important from the point of view of health aspects. from the collected data, arithmetic means, geometric means, peak concentration values were determined to compare between the two categories of indoor environment. the results show the two environments to be significantly different. also, the results indicate remarkable high indoor surface area concentrations during the cooking and other combustion processes. keywords fine particulate matter, surface area concentration, air quality, indoor combustion, real-time measurement 1. introduction solid or liquid particles suspended in air form aerosols. particulate portion is usually referred to as particulate matter (pm). pm is chemically and physically diverse substance and range in a wide size range. aerosols are generated from various sources such as dust, soil, volcanic eruptions or due to anthropogenic processes like combustion activities, agricultural, commercial or industrial practices. then they also change because of processes such as condensation, nucleation etc. for indoor concentration of aerosols, we can consider the following as the sources: cooking, smoking and other combustion activities, pollen, fungal spores, molds, and bacteria, besides the influx of outdoor aerosols such as road and soil dust. fine particulate matter caused air pollution has been considered in recent years as a serious environmental concern. recent studies (bruce et al., 2000; smith, 2000) have found that the respiratory diseases such as tb, cardio-vascular diseases, copd etc. are associated with the long-term exposure to www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 2 published by scholink inc. fine particulates. india has second highest per capita burden of respiratory illnesses in the world (smith, 2000). about one million deaths are reported annually in india due to household air pollution caused by fumes from cooking, heating and lighting activities. till few years back, mass concentration (mc) of pm was used to assess the health impacts. now we know other metrics such as number concentration (nc) and surface area concentration (sac) metrics are important as well and this is confirmed by the studies on cell cultures and animal respiratory system (brown et al., 2001; oberdorster, 2000; tran et al., 2000; heitbrank et al., 2009). we have already studied and reported the results on number and mass concentration in indoors (monkkonen et al., 2004). of all the pms, the fine particulates (0.01-2.5 µm) have a greater probability of delving deep into the lungs (zhou & cheng, 2000; churg & brauer, 2000). ratio of surface area to mass becomes greater as we move towards small diameter particles. for a given mass, surface area increases as 1/diameter. hence the necessity for expressing the regional dose in terms of surface area concentration in the epidemiology studies. jicheng gong et al. (2019) study shows that particle size ranges having large sac and/or volume concentration have significant positive association with pulmonary inflammation. the recent usepa particle size chosen as standard for epidemiological studies is pm2.5, which are particles smaller than 2.5 micrometer in mean aerodynamic diameter (usepa; 1996; schwartz et al., 1996). in the (sahu et al., 2011) study conducted in rural india, the correlation between pm2.5 and surface area concentration was found to be low to moderate. the study showed correlation coefficient r=0.38 in the tracheobronchial region and r=0.47 in the alveolar region. this indicates that pm2.5 is not a sufficient proxy for particle surface area concentration. however, to conform to the latest findings, new standard of pm2.5 is to be adopted for further study. the usepa clean air scientific advisory committee (casac) review (wolff, 1996) suggested a 24-hr pm2.5 standard in the range of 20 to 65 µg/m 3 . many studies (kamens et al., 1991; lighty et al., 2000) have indicated that cooking is the primary activity responsible for generating fine particles in indoors. according to kamens et al. (1991) study, particles below 1 µm are major constituent of the emission. the average diameter of these particles in the emission was around 0.8 µm. a recent study (patel et al., 2020) has confirmed this where they found that nc was highest for sub-10 nm particles during cooking activity with kerosene stove. in such a study, some of the important tasks included are: measurement of exposure with a particular exposure metric, comparing them with the existing emission or exposure standard, understanding their impact on the exposed population, and also carrying out source-apportionment of the aerosols monitored. in india, many studies have been conducted on the health effects of biomass fuel usage (smith, 1986). however, very few studies have compared the kerosene and liquid petroleum gas lpg fuels which are also commonly used for household purposes. according to a recent study (elf, jessica l et al., 2018), 57% of urban homes use lpg as the lone and primary fuel, whereas kerosene and wood is used as a secondary main fuel in about 22-25% of homes. www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 3 published by scholink inc. in india, especially in economically poorer section, women spend primary part of their time indoors cooking with crude fuels with poor ventilation and, also the stoves are inefficient. kerosene is being used by economically lower-class people who live in poorly ventilated small houses. studies in india have concentrated on the mass concentration of pm10 and pm5. in the present study sac of fine particles are measured. we are going to compare the obtained data with respect to the type of fuel used indoors and as well as study their variation patterns. the present study is conducted in mysore city situated in the state of karnataka having average minimum temperature of 15 o c and maximum temperature is 35 o c. it is a small city with a population of 893.062 (census of india 2011) and an area of more than 150 sq. km. cooking activities using kerosene and lpg as main fuel with poor ventilation facility found in many of the houses. 2. method in the process of aerosol measurement, the first part is collecting a small sample from the bulk aerosol for analysis. the process is referred to as aspiration. these particles are transported to the measurement instrument. the particles are analyzed in real-time (dynamic measurement). prior to the collection or analysis, an additional step called pre-classification is added to get an expected aerosol for sampling. for example, when we want to measure particles smaller than 10 µm, we have to remove all particles of size larger than 10 µm before collecting the sample. 2.1 instrument used diffusion charger (e.g., lq1-dc, matter engineering, ag) the technology necessary to measure aerosol exposure in terms of sac is not widely available. in the present study we are going to use lq1-dc (matter engineering, switzerland), to directly measure active surface area by the method of diffusion charging. figure 1. mechanism of unipolar diffusion charging source: www.matter-engineering.com www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 4 published by scholink inc. the unipolar diffusion charging mechanism used is shown in figure 1. a small positive voltage of approx. 20 v dc is applied to the grid. aerosols in the gas stream are guided between the grid and the grounded tube. with the corona discharge from the corona tip to the grid, ions get produced in the carrier gas. these ions attach to the surface of the aerosol particles. the particles carrying positive charge flow to the sensor unit and are absorbed in the measuring filter. the filter is connected to a ultra low current amplifier (resolution 1 fa=10 –15 a). the voltage signal from the charge amplifier is converted to the calibrated analogue signal 0…5 v dc. this signal is displayed as 0…1000 after adjustment. the lq1-dc instrument measures the integral attachment cross section of ions on particles. it is the part of the geometrical surface which is directly accessible from outside; hence the use of term “active surface” or “fuchs surface area”. the measurement gives the total active surface area per unit volume. to overcome multiple charging for particles larger than 10 nm, the in concentration is kept low. due to coulomb repulsion, the ion attachment rate in case of multiple charging decreases. we now discuss the technical specifications, pre-sampling set-up, of the instrument lq1-dc used for measuring the sac. figure 2. lq1-dc instrument to measure surface area concentration data logging time-interval for indoor measurements was set to 10 sec. before each sampling, electrical zero is adjusted to zero using potentiometer. response time: few seconds particle size range: few nm to 2µm. resolution: 1 µm 2 /cm 3 gas flow rate: approx. 1.5 l/min 2.2 sampling procedures the study is carried out in the city of mysore in different households using either kerosene or lpg fuel for cooking. five houses of each type were randomly selected from different parts of the city. kerosene and lpg houses were chosen in pairs such that a kerosene house lied in an area close to a lpg house. www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 5 published by scholink inc. it was also noted during the selection of the houses that the households also used some other fuels wood, dung cakes etc. all measurements were carried out in the period from august to january. on the day of sampling, the lq1-dc instrument was taken to the sampling location and were run by battery for 24-hr to collect the real-time sac data. the instrument was kept in the living room at a height of about 50 cm from the floor. main activities within households including cooking were noted down by the family member along with the corresponding timings. after a gap of 4 months, measurements were repeated for the second time in each house. the sampled data stored in the memory unit were downloaded to the pc from the instruments after each sampling. 2.3 analysis of the data statistical analysis of 1-minute-average time-aligned data file was made using microsoft excel software. statistical entities like the arithmetic or geometric mean averages, standard deviation and variance were calculated from data files of each sampling site using the functions provided in the software. these results were used to make comparisons between the two types of environments. also, variation aspect of the metric data was studied with these results. the two types of sampling categories were checked for statistical differences in terms of metric concentrations. to find statistical difference, following procedure was used. first, the mean and standard error of the surface area concentrations of two groups, e.g., kerosene and lpg houses were obtained. let the number of houses for kerosene and lpg groups are n1 and n2 respectively. the standard error for each group, e.g., kerosene group is obtained as 𝑆𝐸 = 𝑆𝑡𝑑.𝐷𝑒𝑣𝑖𝑎𝑡𝑖𝑜𝑛 𝑠𝑞𝑢𝑎𝑟𝑒 𝑟𝑜𝑜𝑡 𝑜𝑓 (𝑁) the two groups are statistically different if their error bars do not overlap. for example, let the mean and standard error for kerosene be m1 and se1, and those for lpg be m2 and se2. then if (m1-se1) > (m2+se2), (i.e., the lower bound for kerosene is greater than the upper bound for lpg) then, the two groups are statistically different. otherwise, the two groups are not different. the statistical results of the analysis in the present study are presented in the next section in terms of averages and standard deviation representing the particular environmental category. standard deviation actually gives the amount of dispersion involved in the metric levels. from the variation levels, we can know if any significant change in concentration levels occurs over a day, or over different sampling sites. 3. results and discussion in this section, we will discuss analysis of the data collected to know the particular association of some of the sources with concentration levels, the daily variation pattern, and the average sac concentration levels for the two indoor categories and comparison between them. www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 6 published by scholink inc. 3.1 association of peaks with activities. the data collected from the lq1-dc were mapped with the activities recorded by the housewife in the activity log sheet. following associations were found in general. cooking activities identified with the peaks i. heating water for bath: time: morning 6 to 9 am, a high unique peak ii. breakfast: time: morning 7-9 am iii. meals: time: morning 11-12 noon, a moderate peak iv. evening cooking: time 5-7 pm, moderate peaks v. late night: 11 pm-4 am, steep decrease in concentrations reaching minimum levels. along with the cooking fuel, the household were found to use alternate fuels such as coconut husk or dung cakes. the unique high peaks observed in surface area concentration corresponded to this activity of heating water for bath noted down in the activity log sheet which usually occurred in the morning hours from 6 am-9 a.m. (see figures 3 and 4). this is a major aerosol generating activity and usually would last for 2-3 hours. other peaks during the day also corresponded to the activities noted down in the activity log sheet. all other peaks afterwards are found to be associated with the household activities mainly the cooking processes, such as preparing tea, breakfast, meals, etc. so, to further understand the association of aerosol properties with the activities, it is necessary to study each of the peaks relating to the particular activities in detail. figure 3. indoor sac variation over 24-hours 1.00e+07 1.00e+08 1.00e+09 1.00e+10 8:38 13:26 18:14 23:02 3:50 8:38 su rf a c e a re a c o n c . time (hrs) indoor s.a. concentration, µm2/m3 www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 7 published by scholink inc. 3.2 variation pattern over a day the sac variation pattern was similar across the different sampling locations, except during combustion activities. corresponding to the each particular combustion activity, fuel-specific particle emission takes place influencing the concentrations as well as the size ranges. there was difference in the nature of the peaks from one activity to another which was evident through the graphical plots of the concentration as well as the activity log sheet. this corresponds to the source-specific nature of the aerosols generated. after constant low levels of concentrations in the early hours of the day, sharp peaks are seen from around 5 a.m. to 9 a.m. due to the inflow of particles onset by activities and wind flow. moreover, after around 6 am to 9 am, combustion activities start to take place. these usually include heating water for bath, preparing morning breakfast, and even sweeping. figure 4. indoor sac variation over 24-hours usually, the afternoon period of 12-4 pm was found to be little calmer durations with lower concentration levels. concentrations rise to moderate levels from around 5 pm-7 pm and variation pattern is similar to early morning hours, but with little lower concentration levels. this is found to be due to the increase in outdoor activities like movement of vehicles, or due to smaller-duration cooking activities which included preparing tea, snacks, and sometimes dinner also. in the late-night hours, after about 11 pm, there was a steep decrease in concentrations reaching a minimum and remaining constant at that level till around 4-5 am. after 11 pm, family members are taking rest; hence there is no disturbance causing the coarser particles to gradually settle down. no unique difference in variation was found during this period between kerosene and lpg houses. 1.00e+07 2.10e+08 4.10e+08 6.10e+08 8.10e+08 1.01e+09 1.21e+09 21:00 23:05 1:10 3:15 5:20 7:25 9:30 11:35 13:40 s u rf a c e a re a c o n c . time (hrs) s.a. concentration in µm2/m3 www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 8 published by scholink inc. nighttime average values of concentration during 12 p.m.-4 a.m. are considered as background concentration levels. since it is no-activity period, there will be fewer disturbances for aerosol movements. we can refer to results from other studies in this. study by (kamens et al., 1991) showed that at midnight, when everyone in the house had gone to sleep, aerosol concentration declined indicating the settling of larger particles. our study also showed similar results. the activity log-sheet was helpful to know the cause for unusual variations in concentration levels. the plot shown above (figure 3 and figure 4) represents an indoor daily variation with a sudden peak around midnight. the sudden peak is because of the doors being opened when one of the house members came late in the night, which might have caused the wind in-flow, resulting in random movement of the settled particles. it can also be observed from the plot that later on, the concentration levels remained higher than the usual levels throughout the night, with a small gradual decrease in concentration. study by (kamens et al., 1991) has showed that the fine particle levels after a peak would remain high for a longer period. for urban locations, within-day variation was found to be about 2-3 times higher than between-day variation. but for remote locations, not so high difference was found between the two, indicating the influence of lesser sources and activities. 3.3 concentration levels of the metric data downloaded from the lq1-dc after each sampling was 1-min average data of sac. from 1-min average data, statistical results such as arithmetic mean, geometric mean, and standard deviation etc. were obtained for all indoor sites. table 1 gives the summary of average concentration, their standard deviation for indoor measurements. lpg house sac concentrations are little lower compared to the kerosene households. one of the kerosene houses sampled was in a slum area, with poor ventilation facility within the house; the influence from neighboring houses also was large, because of too much congestion. in two other kerosene houses, the neighboring house influence on the concentration was large. one kerosene and one lpg house had dusty surrounding environment. statistical difference was found between the two groups for sac as the exposure metric. variance among the households is nearly the same among the two groups. www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 9 published by scholink inc. table 1. 24-hr average data of the metrics from indoor measurements with kerosene and lpg as the main fuel house id kerosene house lpg house metric values in each house metric values in each house surface area conc. (0.01-2.0) µm 2 /m 3 surface area conc. (0.01-2.0) µm 2 /m 3 1 1.63e+08 1.49e+08 2 4.30e+08 6 2.99e+08 3.45e+08 7 7.79e+08 8 9 4.31e+08 10 7.76e+08 11 3.77e+08 1.37e+08 s.d. (µg/m 3 ) 55.34 46.31 variance (%) 54.54 62 standard error (s.e.) is found out for the two groups using s.d. from table 1, using the formula discussed earlier. later, we find that kerosene (mean-se) > lpg (mean+se) indicating that the two indoor categories, viz., kerosene and lpg households are statistically different. table 2 shows the ratio of concentrations found in two categories of houses is 1.79 indicating that usage of kerosene fuel is leading to higher concentrations than lpg. thus lpg is a cleaner fuel than kerosene. table. 2. indoor measurements in houses: 24-hr a.m. values of surface area concentration (0.01-2 µm) (n=5) (background indoor pollution: 36+16 µg/m 3 ) kerosene house lpg house kerosene/lpg ratio: range and g.m. (4.71+2.54)e+08 µm 2 /m 3 (2.65+1.46)e+08 µm 2 /m 3 1.76 to 1.82 gm=1.790 considering both groups of houses in general, for surface area concentration, the ratio of 24-hr mean to background value for each house is found to vary from 1.6 to 3 with an average of 2.5. this shows the influence of the combustion activities which increases the pm concentration to more than two times the normal levels. for instance, in one kerosene house, sac was found to exceed 2000 µm 2 /cm 3 two times www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 10 published by scholink inc. in a day. these levels are potentially harmful to the inhabitants who get exposed to them on a daily basis. the ratio of peak value to 24-hr mean value for each house is found to vary from 4 to 66, with an average of 21.2. this shows the impact of emissions during combustion activities to increase the pm concentrations from normal levels to more than 21 times. this indicates how some combustion activities can create really high dose of short-term particulate exposure to the inhabitants. ventilation facility in the house influences the concentration levels very much. results from earlier studies have also shown the dependence of pm2.5 exposures on the ventilation levels within the houses (sarnat et al., 2000). in some cases, the outdoor sources had a major effect on the exposure levels indoors. 4. conclusion national ambient air quality standards (naaqs, 2009) in india stipulate standards for pm2.5 at an annual average of 40 µg/m 3 and 24-hr average of 60 µg/m 3 . however, there are no standards specified for sac. houses using kerosene fuel for cooking were found to be more (about 1.79 times) polluted with particulate matter than the houses using lpg. every cooking activity resulted in concentration peaks. indoor peak values were seen to be about 20 times higher than the 24-hr mean values. indoor average concentrations exceeded background values by more than two times. in kerosene-using houses, generally poor ventilation facility and congestion was found. heating water for bath during early morning hours was one major aerosol generating activity which lasted for 2-3 hours. peaks during heating water for bath in each house were found to far exceed the peaks during the other activities. this indicates the influence of the crude fuels like wood, dung cakes etc. similar peak was found daily during evening times between 5 p.m. and 7 p.m., mostly due to the increase in outdoor activities, and penetration of outdoor particles into the houses. for kerosene and lpg fuel types, not much difference in daily variation pattern was found. in the light of health effects associated with aerosol exposure, results of the present study indicate alarmingly high exposure to household women who spend majority of their time indoors doing cooking. there is a risk of high-dose of short-term exposure to the inhabitants. there is the need to ensure that their exposure to particulate matter is well within the permissible limits for a healthy living. may be good ventilation facility within living room and kitchen, cleaner fuel and efficient stoves etc., can lessen the exposure levels to these particulates generated. also, the use of kerosene fuel, wood and dung cakes etc., will have to be replaced by better fuels like liquid petroleum gas (lpg). the latest survey released by the national sample survey organization (nsso, 2012) has revealed that in rural areas, subsidized kerosene was used in less than 1% of kitchens, which relied largely on firewood and chips as the primary source of energy for cooking during 2011-12. more than 67% of rural households in india still depend on firewood or wood chips for cooking. in contrast, around 68% of urban households use lpg for cooking. when it comes to lighting homes in villages, the share of www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 1, 2021 11 published by scholink inc. kerosene is estimated at 26.5%, with electricity's share estimated at 72.7%. in urban india, 3.2% of households use kerosene for lighting while the share of electricity is 96%. the encouraging aspect in urban households is that the use of kerosene has declined from more than 23% to 6%. consumption of kerosene, used primarily for lighting and cooking purposes in rural areas, has dropped by a sharp 21% in 2016-17 from a year ago aided by greater use of cleaner liquefied petroleum gas (lpg) for cooking and coverage of more villages under the rural electrification program, as per data from petroleum planning and analysis cell, an arm of the oil ministry. in the same period, consumption of lpg jumped by 9.8%. in 2016-2017, there were issued a total 3.25 crore new lpg connections, the highest number of connections given in any year ever. this number included the 2 crore connections given under the “lpg-for poor women” scheme, the pradhan mantri ujjwala yojana (pmuy). india’s fossil fuel consumption trend is suggesting a shift away from inefficient and highly polluting use of hydrocarbons, as a result of efforts to move towards a less-carbon-intensive economy. recent who pollution report mentions this scheme saying “india’s pmuy scheme has provided some 37 million women living below the poverty line with free lpg connections to support them to switch to clean household energy use” (who, 2018). worth mentioning also are some of the non-government organizations such as confederation of indian industry (cii) which has established the indian green building council (igbc) and working closely with state governments and central government in promoting green building concepts in india (https://igbc.in/). the present study has setup a database for sac metric at two indoor environments in a medium indian city and initiated a study of the association of peaks with cooking activities and the variation pattern of the metric. this kind of study may become more satisfactory with the rigorous study of peaks associated with combustion activities, as to the particle size range, density or morphology of particles generated by different sources. acknowledgement the author is grateful to dr. andrew maynard and the university of mysore which gave permission to use the instrumentation facility mentioned in the article. references brown, d. m., wilson, m. r., macnee, w., stone, v., & donaldson, k. 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hand held mobile multi-gas monitor with model as8900 (combustible (lel), and oxygen (o2)), blatn with model br—smart series air quality monitor (pm10, formaldehyde) and air quality multimeter with model b side eet100 (dust (pm2.5), voc, temperature and relative humidity). the results show that the mean concentrations of co, o2 and other measured parameters such as formaldehyde (hcho) etc., are commonly lower and within acceptable range of national and international regulatory standards for air quality indices. there are however some exceptions such as mean concentrations of volatile organic compounds (vocs), pm2.5, pm10 and combustible (lel) respectively high when compared to national and international standards. this high value is attributed to the amount of pollutant present in the sawmills due to the input of influents it receives from activities of the sawmill. this is why there has been air pollution in ilorin metropolis and were however, found to be polluted. given the high cost of additional measures to lessen air pollution and the new perspectives suggesting that health effects can be observed at low concentrations, the health effects of air pollution should be of scientific and regulatory interest in coming years. in the absence of aggressive control, ambient air pollution is expected to cause between 6 and 9 million deaths a year by 2060. keywords non-communicable diseases, quantified risk factor, neurodevelopmental disorders, neurodegenerative diseases, acute lower respiratory infection (alri), mental disorders, sawmills 1. background of the study high levels of air pollution are a known risk factor for child health, particularly childhood pneumonia and still remains at dangerously high levels to the health of the environment and have significant immediate effects, especially around the sawmill. the snag, however, is that the rapid development recorded in the building construction sector is the result of high proliferation in the setting up of sawmills in several fragments of the country to satisfy the mounting wood demand, its activities and processes in the sawmill industry. they yield both well-known and unknown gaseous contaminants that are released into the atmosphere that can be hazardous to public health. report from world health organization shows that in 2016 nearly one in five deaths attributed to ambient air pollution were caused by acute lower respiratory infections meaning 18% were ascribed to acute lower respiratory infection (alri) and recent studies reported that even short-term exposure to air pollution can cause alris, making the body more prone to infection or less able to fight it. research has revealed nasal cancer and asthma are highly associated with continuous exposure to wood dust and other substances used in the wood industry (anavberokhai, 2008). the short-term deleterious health effects of air pollution exposure are well documented (ruckerl et al., 2011; heroux et al., 2015; raimi et al., 2018). air pollution, especially particulate matter (pm), poses public health problems due to its toxicity and the widespread human exposure to this pollutant. pm, including aerodynamic diameter with inhalable particles below or equal to 10 µm (pm10) and fine particles of an aerodynamic diameter equal to or www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 3 published by scholink inc. below 2.5 µm (pm2.5), are emitted by combustion sources or are formed by transformation of atmospheric chemistry. given evidence of health effects, average daily and annual concentrations of pm10 and pm2.5 are regulated in accordance with air quality guidelines (world health organization, 2006) and in major countries. all over the world, both developed and developing countries, the health risk of urban dwellers due to particulate matter are well documented (wilson & spengler, 1996; raimi et al., 2018). to estimate health damage associated with air pollution in emerging countries such as nigeria, policy makers are often forced to extrapolate results from studies in industrialized countries. however, these extrapolations may be inappropriate for two reasons. first, it is not clear that the relationship between pollution and health at relatively low levels of pollution in industrialized countries applies to the extremely high levels of pollution found in developing countries. for example, particulate matter levels are often three to four times higher in developing countries than in industrialized countries. secondly, people in developing countries like nigeria die earlier and for reasons other than those in industrialized countries, suggesting that extrapolating the air pollution effects on mortality can be particularly misleading. schematically, in an increasingly complex industrial society, increasing attention is being paid to technological risks replacing natural hazards as the greatest environmental threat to human life and property. because economic development is crucial to urban development and growth, economic development has not only brought growth and prosperity, but ultimately economic decline and environmental problems have also affected the regions. rapid urbanization and industrialization have increased the vulnerability of individuals to various man-made dangers. for most people, the real threat is experienced indirectly. however, a significant number of people are directly confronted with an unhealthy environment simply because of their geographical location, living in an area where the real hazards occur. this is the case with residents of the major saw mills in ilorin, kwara state, nigeria. within the major sawmills, the proximity of sawmills industry and housing has created a certain amount of controversy about the environmental quality. residents’ right to enjoy the benefits of clean air is limited by the activities of the timber industry. as a result, concerns are raised about the impact of pollution on health. at least a quarter of the world’s population is exposed to the risk of air pollution (who, 2006), and the loss of nearly 6.4 million years of a healthy life is associated with chronic exposure to ambient particulate matter (who, 2006; raimi et al., 2018; raimi et al., 2019). expert panels for the u.s. environmental protection agency, united nations, and other agencies have consistently cited air pollution as a greater health hazard than water pollution (freeze, 2000). both particulate matter (pm) and ozone (o3) are associated with a number of deleterious effects on human health, and in fact there is no threshold that has been established under which these pollutants exert no adverse effects (daniel, 1989; who, 2006; bell et al., 2013). what we do not know is the difference in the amount of air pollutants concentrations within sawmill environment. do the levels of air pollution vary significantly within sawmill environment and, if so, is there a pattern to such variability? www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 4 published by scholink inc. pollution has become one of the major threats to global health and existential challenges of the 21st century and 4th industrial revolution with more than 90% of the deaths occuring in low and middle income countries, mainly in asia and africa but also in the eastern mediterranean, europe and the americas. despite changes in climate, loss of biodiversity, acidification of the ocean, drought and desertification, and global fresh water supply depletion, earth’s support systems and its sustainability is endanged by pollution and threatens the current existence of human societies and its association (rockstrom et al., 2009). health effects of air pollution will affect many communities in the coming years and endanger the lives and wellbeing of billions of people at increased risk. pollution, particularly vehicular exhausts, emissions from industries and toxic chemicals, has significantly increased over the past 500 years, and are considered the largest increase in emerging countries today. yet despite its great and mounting magnitude of vehicular, industrial and pollution from chemical in emerging countries has been principally overlooked in global development and international health agenda, and pollution control programmes have shown little attention or resources from either global agencies or development partners, i.e., philanthropic donors. currently, pollution has become a major problem that threatens the health of billions, worsens the earth’s ecosystems, weakens the economic security of the country, and is accountable for a vast worldwide burden of disease, disability, and premature death. pollution is closely associated with global climate change (mcmichael et al., 2017; perera, 2017). combustion of fossil fuel in developed and middle-income nations, and biomass burning in inefficient cook stoves, open fires, agricultural burns, forest burning, sawmill activities and outdated brick kilns in emerging countries are responsible for 85% of airborne pollution particulate and for nearly all oxides of sulphur and nitrogen pollution. combustion of fuel is a main source of greenhouse gases and short-lived pollutants due to climate that are the key anthropogenic drivers of human climate change (gaveau et al., 2015; johnston et al., 2012; scovronick et al., 2015). pollution is expensive; it is held responsible for productivity losses, costs of health-care and associated costs from ecosystems damages. regardless of the great extent of these costs, they have not been seen and are not recognised as caused by pollution (national academy of sciences, 2010). the productivity losses of pollution-related diseases and health-related costs are buried in labour statistics and in hospital budgets (landrigan & fuller, 2015). the pollution consequence is that the complete costs are underestimated and not appreciated, are often not counted, and are not accessible to refute one-sided, against pollution control that are economically based arguments (national academy of sciences, 2010; epstein et al., 2011). the changing nature of air pollution in many places around the world is worsening particularly at sawmill environment. these changes reflect increased consumption of energy, increased usage of novel materials and technologies, the rapid industrialisation of low-income and countries of middle-income and the global populations shift from areas of rural into cities. air from household and pollution from water are methods of pollution that remained traditionally associated with extreme poverty and historical lifestyles, are slowly declining. however, ambient air pollution, pollution from chemical and land pollution, are all increasing (smith & ezzati, 2005; omran, 2005). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 5 published by scholink inc. the main causes of this pollutants type remain: the unrestrained development of cities (wilkinson et al., 2007); increasing demands for energy (ebuete et al., 2019); increasing mining, smelting, and deforestation (raimi et al., 2019); the global blowout of toxic chemicals; progressively heavier applications of insecticides and herbicides; and an increasing use of petroleum-powered cars, trucks, and buses. ambient air increases in soil and chemical pollution over the last 500 years have been linked to the immediate widespread, linear, take-make-use-dispose economic reforms termed by pope francis “the throw away culture” (pope francis, 2015) in which natural resources and human capital are widely regarded as commercially available and expendable, and the significances of their careless exploitation are given little attention (whitmee et al., 2015; raworth, 2017). the understanding of the science of environmental pollution and its impact on health has made great progress (national academy of sciences, 2012; brauer et al., 2012; olalekan et al., 2020). new technologies, including satellite imagery (sorek-hamer et al., 2016), have improved the capacity to map pollution, detect the level of pollution remotely, detect pollution patterns, and monitor seasonal trends (brauer et al., 2012). sophisticated chemical analyses have provided a better understanding of the pollution configuration and revealed the relationship between pollution and disease (valavanidis et al., 2008; suleiman et al., 2019). the probability of a major disease being discovered indicates that certain pollutants are associated with a greater number of diseases, particularly non-communicable diseases, than was hitherto known. pollution is now known to be a significant contributing factor for numerous non-communicable diseases such as neurodevelopmental disorders, asthma, cancer and in children, birth defects with heart disease, stroke, chronic obstructive pulmonary disease and in adults, cancer (loomis et al., 2013; thurston & lippmann, 2015). in the lack of aggressive interference, the level of air pollution mortality rate will increase by more than 50% by 2050 (lelieveld et al., 2015). despite these scientific advances, much remains to be said about the effects of the pollution and their public health effects. the shortcomings comprise the lack of evidence in many nations on measures taken to combat pollution and the frequency of pollution-related disease and its effects; poor knowledge of the harmful effects of chemicals on specific public use, especially, novel classes of chemicals (landrigan & goldman, 2011; grandjean & landrigan, 2014); insufficient information on the level of exposures and disease burden associated with lethal exposures at contaminated environment and insufficient information to account for the likely overdue effects of lethal exposures continued in the beginning of life (heindel et al., 2015). the exact dose-response nature of the model used to assess risk of disease linked with air pollution is unknown. for example, with regard to fine-particulate air pollution, the exposure shape response group, both at lower and very high levels of exposure is much less pronounced and the expectations that underlie the integrated exposure response function used to appraise the relative hazards of fine particulate (pm2.5) exposure in both the global burden of disease (gbd) study and who studies are not exactly known (burnett et al., 2014; global burden of diseases study, 2015; cohen et al., 2017). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 6 published by scholink inc. 2. objectives of the study this study aims at assessing major sawmill environment ambient air quality in ilorin metropolis, kwara state, nigeria. to achieve this aim, the following specific objectives are to: i. examine the relationship among co (ppm), pm2.5 (ug/m3), pm10(ug/m3), h2s (ppm), voc (ppm), lel (%), formaldehyde (mg/m3), oxygen (o2), temperature (o0c) and relative humidity (rh) in the study area. ii. compare air quality with international and national acceptable standards. iii. compare the concentrations of co, pm2.5, pm10, h2s, voc, lel, formaldehyde, oxygen (o2), temperature and relative humidity. iv. make the necessary recommendations from the findings to the residents of the major sawmills in ilorin metropolis, kwara state, nigeria. 3. study area 3.1 location ilorin, the capital of kwara state is located on latitude 8º30’ and 8º50’n and longitude 4º20’ and 4º35’e of the equator (figure 1), with a population of over one million people (2006 census). ilorin city occupies an area of about 468 sqkm and it is situated in the transitional zone within the forest and the guinea savannah regions of nigeria. it is about 300 kilometres away from lagos and 500 kilometres away from abuja the federal capital of nigeria. its elevation ranges from 250 to 400 m above sea level. it is also the headquarters of the ilorin west local government area (lga) which is surrounded by other lgas of the state. this gives her roles as the commercial and administrative capital of the state, the headquarters of ilorin west lga, and together with ilorin east, ilorin south, asa and moro lgas they constitute the ilorin emirate. the location of ilorin west is shown in figure 1. ilorin has diverse ethnic groups of mainly yoruba, fulani, hausa, kambari, gobir, and nupe, that constituted it. the multi-linguistic and multi-cultural nature of the people could be traced to their historical background. ilorin is said to be founded as hamlets in 17th century by an itinerant farmer called ojo from gambe near oyo-ile. the hitherto existing hamlets were in 1830s consolidated under the sovereignty of fulani hegemony by abdul-salam, the son of sheikh alimi. the total population of ilorin west lga is 365,221 in 2006. this is comprised of 180,387 males and 184,834 females; being the most populous lga in kwara state that has 3.0% as its growth rate (npc, 2006). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 7 published by scholink inc. figure 1. map of kwara state showing the study area 3.2 climate ilorin climate is tropical under the influence of the two trade winds prevailing over the country. according to ifabiyi (1999) and raimi et al. (2018), the climate of the city of ilorin is tropical continental with high temperature throughout the year. it is characterised by wet and dry seasons. ilorin falls within derived savannah vegetation, covered with the existence of dry lowland rain forest vegetation cover. the wet season is between march and october whereas the dry season is between the months of november and february. the total annual rainfall in the state boundary of the north ranges from 800 mm to 1200 mm, in the north western parts of the state and have 950 mm to 1300 mm while in the southeast is 1000 mm to 1500 mm. kwara state has several rivers which include: river asa, awonriver, oshin and moro in the central state. likewise, the monthly mean temperature is generally high throughout the year. the daily average temperatures are in january with 25ºc, may 27.5ºc and www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 8 published by scholink inc. september 22.5ºc. while humidity is relatively moderately high the amount of rainfall in the southern part is relatively higher than what is experienced in the northern part of the studied area. 3.3 vegetation the vegetation is mainly within the deciduous woodlands of southern nigeria and the dry savannah of nigeria. these are essentially made up of grass cover, shrubs and medium sized trees of the guinea savannah type (olaniran, 1982; ileoje, 1985; raimi et al., 2018). the vegetation of ilorin is composed of species of plant such as locust beans trees, shear butter trees, elephant grasses, shrubs and herbaceous plant among others are common in this area. the vegetation of the study area has partial rainforest, but most parts of the area are savannah-like with tall grasses and scattered trees. 3.4 topography and drainage the drainage system of ilorin is dendritic in pattern due to its characteristics. the most important river is asa river which flows in south-northern direction. asa river occupies a fairly wide valley and goes a long way to divide ilorin into two parts namely the eastern and the western part. the major rivers are asa, agba, alalubosa, okun, osere and aluko. few of these rivers drain into river niger or river asa (oyegun, 1986; cited in raimi et al., 2018). the general elevation of land on the western part varies from 273 m to 364 m (i.e., 900 to 1/200 ft) above sea level. to the north of the western part of ilorin exists an isolated hill known as sobi hill which is about 394 m high above sea level. the state has river niger as its natural boundary along its northern and eastern margins and shares a common internal boundary with niger state in the north, kogi state in the east, oyo, ekiti and osun states in the south and an international boundary with the republic of benin in the west. it is therefore appropriate to say that the state is indeed a middle belt state serving as a “gateway” between the north and the south and in fact a “melting point” for the northern and southern cultures of a relatively flat and undulating land with interine and lacustrine deposits, sparsed hills and valleys in parts of baruten, kaiama and moro local government areas. 3.5 land use the major occupation of the people is mixed farming. the wide expanse of arable and fertile soil and favourable climatic conditions supported the cultivation of variety of food and cash crops, including cashew, yam, beans, groundnut, varieties of vegetables, maize and guinea corn. the rearing of animals is made possible due to the existence of savannah type of vegetation. other prominent economic activities include cloth weaving, pottery making, blacksmithing, shea butter production, and gum processing (raimi et al., 2018). 3.6 sample collection collections of samples were restricted to air quality. air quality sources was selected randomly within the vicinity of the study area, but at different distances from each other for the purpose of this study. also, the collected samples were at different locations. these locations include: kanisuru sawmill, eiyenkorin sawmill, oluwaniagbaraemimi saw mill, olowoyeamoyo sawmill, odo-okun sawmill, irelopeojaoke sawmill, irewolede sawmill, ibudo osho sawmill, asa dam sawmill, akerebiata www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 9 published by scholink inc. sawmill, oluwaseun sawmill etc (see figure 1 above). the monitoring exercise were taken in the daytime, between 9.00am and 6.00pm. night samples was not collected. sampling was carried out between 1st july 2019 through 1st of august 2019 within major sawmill environment in ilorin metropolis, each day for a period of one month on an alternate day. 3.7 equipment employed 3.7.1 handheld gas detector hand held mobile multi-gas monitor with model as8900 (carbon monoxide (co), hydrogen sulphide (h2s), combustile (lel), and oxygen (o2)), blatn with model br—smart series air quality monitor (particulate matter (pm10), formaldehyde) and air quality multimeter with model b side eet100 (dust (pm2.5), voc, temperature and relative humidity) equipment will be used to detect the presence and precise quantity of the following individual gases, viz: carbon monoxide (co), particulate matter (pm2.5), particulate matter (pm10), hydrogen sulphide (h2s), volatile organic compound (voc), combustile (lel), and oxygen (o2). 3.7.2 global positioning system (gps) spatial positioning of different sawmill locations was collected through the use of a hand held global positioning system. the gps was helpful in obtaining the selected areas in the community and data obtained was used to produce a digital map through the arc view gis software. 3.8 statistical analysis mean, standard deviation and coefficient of variation were calculated for each of the parameter (oxygen, voc, pm2.5, pm10, lel, formaldehyde, temperature and relative humidity). pearson correlation was used to determine the correlations between the parameters. also, the relationship of these parameters and distance was analysed using pearson correlation. levels of these parameters relative to their respective fmev and who standards were compared for statistical significance using one sample t-test. furthermore, data obtained was also analysed using multiple linear regression. statistical significance was calculated at 0.05 level of significance with p<0.05 indicating the statistical significance. all data analysis and computations of result were performed using the statistical package for social sciences (spss version 22.0). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 10 published by scholink inc. 4. results table 1. correlation between the variables in the study area (kwara state) variables 1 2 3 4 5 6 7 8 9 10 1. temp (o0c) 1 2. rh 0.02 1 3. voc (ppm) -0.28 -0.03 1 4. co (ppm) -0.14 0.06 -0.39** 1 5. o2 -0.18 0.07 0.34** -0.35** 1 6. pm2.5 (ug/m3) 0.07 -0.08 -0.13 0.38** -0.18 1 7. pm10 (ug/m3) 0.05 -0.12 -0.15 0.37** -0.07 0.99** 1 8. hcho (mg/m3) 0.35* 0.03 0.18 0.08 0.26* 0.44** 0.44** 1 9. lel (%) -0.53* -0.06 0.17 -0.06 0.23 -0.18 -0.15 0.02 1 10. elevation 0.18 -0.16 -0.32** 0.37** -0.54 0.06 0.06 -0.21 -0.37 1 note. **significant at 1% (p<0.01), *significant at 5% (p<0.05). table 1 presents the correlation between the parameters. result shows that the level of temperature in the study area has significant positive relationship with hcho (r=0.35, p<0.05) and significantly negatively related to lel (r=-0.53, p<0.01). the concentration of voc was found to be positively significantly related to o2 (r=0.34, p<0.01) while for co (r=-0.39, p<0.01) and elevation (r=-0.32, p<0.01), significant negative relationship was obtained. there was a significant positive relationship between pm2.5 and co (r=0.38, p<0.01), pm10 and co (r=0.37, p<0.01), elevation and co (r=0.37, p<0.01) while between o2 and co, a negative but significant relationship was obtained (r=-0.35, p<0.01). result reveals that o2 there is a significant positive relationship with hcho (r=0.26, p<0.05) but significant negative relationship with elevation (r=-0.54, p<0.05). there was a significant positive relationship between pm10 and pm2.5 (r=0.99, p<0.01), hcho and pm2.5 (r=0.44, p<0.01) while positive significant relationship was established between hcho and pm10 (r=0.44, p<0.01). elevation shows significant negative relationship with lel (r=-0.37, p<0.01). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 11 published by scholink inc. table 2. comparison of air quality in the study area (kwara state) with the recommended acceptable standards air quality parameters n range mean sd fmev who standards temperature 75 21.00-46.40 28.27 7.19 29.5-36.9 relative humidity 75 36.40-53.50 43.46 4.84 4.90-75.9 voc 75 0.00-31.00 4.87 9.06 0.50 0.50 co 75 0.00-23.00 5.44 7.12 50 50 o2 75 20.50-21.10 20.86 0.10 20.9 >23.5 pm2.5 75 0.37-999.00 91.71 118.81 115 75 pm10 63 0.50-999.00 107.78 125.38 150 100 hcho 63 0.00-0.10 0.02 0.02 0.13.1 30.0 lel 66 5.00-15.00 10.61 1.53 5 15.5 table 2 presents results of the comparison of the air quality parameters in the study area (kwara state) with that of the recommended standards as provided by the federal ministry of environment (fmev) and world health organisation (who). result shows that temperature and relative humidity in the study area were higher than the lowest acceptable standard but lower than the highest acceptable. the level of voc and lel were above the recommended fmev standards while co, o2, pm2.5, pm10 were below fmev standards. in relation to who standards, result shows that voc, pm2.5, p.m10 were above the standard while o2, hcho and lel were below the recommended who standards. table 3. comparison of the air quality parameters in the study area of kwara state (temperature, rh, voc, co, o2 and pm2.5) s/n locations temperature (o0c) rh voc (ppm) co (ppm) o2 pm2.5 (ug/m3) 1 asadam 23.88±1.25 a 42.65±5.11a 15.05±10.08 b 0.00±0.00 a 20.90±0.05 a 54.00±12.08 a 2 karisunu 28.29±2.45 b 40.87±4.24 a 0.29±0.18 a 7.71±5.65 b 20.84±0.05 a 75.29±15.17 a 3 ibudoosho 28.00±1.29 b 43.54±4.80 a 0.30±0.23 a 8.00±7.42 b 20.87±0.05 a 204.95±353.58 a 4 irewolede 27.67±1.21 b 41.15±4.65 a 18.70±10.08 b 1.17±2.86 a 20.88±0.08 a 66.83±12.11 a www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 12 published by scholink inc. 5 oluwaseun 27.13±1.96 b 45.81±4.78 a 0.23±0.05 a 2.91±8.12 a 20.86±0.07 a 42.60±29.59 a 6 odookun 43.46±2.84 c 44.08±5.33 a 0.47±1.34 a 4.17±6.69 b 20.81±0.14 a 104.42±91.99 a 7 eyenkorin 22.00±1.26 a 44.60±4.28 a 0.22±0.08 a 13.17±6.46 c 20.77±0.10 a 93.00±4.73 a 8 irelopeojaoke 22.00±1.00 a 40.23±4.72 a 0.20±0.01 a 16.00±0.00 c 20.73±0.21 a 89.67±2.08 a 9 oluwaniagbaraemimi 24.00±1.41 a 44.60±4.28 a 19.20±9.79 b 0.00±0.00 a 20.95±0.08 a 56.17±15.88 a 10 oluwoyeamoyo 23.83±1.33 a 47.03±4.50 a 0.21±0.02 a 6.33±9.81 b 20.88±0.04 a 69.33±17.52 a 11 akerebiata 24.33±1.03 a 41.12±4.59 a 0.40±0.21 a 8.83±4.54 b 20.88±0.04 a 151.67±76.19 a note. similar superscript means not significantly different (p>0.05), different superscript means significantly different (p<0.05). result shows that there is no significant difference in relative humidity, pm2.5, pm10, o2 and hcho between the eleven locations (p>0.05). the mean temperature in odookun was significantly higher than that obtained in other locations while between karisunu, ibudoosho, irewolede and oluwaseun, no significant difference was established in their mean temperature. the level of voc in oluwaniagbaraemimi, asadam and irewolede were significantly higher than that obtained in other locations (p<0.05) while between other location, there were no significant difference in voc (p>0.05). result also shows that eyenkorin and irelopeojaoke reported significant higher level of co compared with other locations (p<0.05). the level of lel in odo-okun was significantly less than that obtained in other locations (p<0.05) while elevation in eyenkorin and irelopeojaoke were significantly higher than that of other locations (p<0.05). table 4. comparison of the air quality parameters in the study area of kwara state (temperature, rh, voc, co, o2 and pm10) s/n locations pm10 (ug/m3) hcho (mg/m3) lel (%) elevation 1 asadam 66.50±15.55 a 0.01±0.01 a 11.00±0.00 b 325.67±5.64 a 2 karisunu 112.71±55.98 a 0.02±0.01 a 10.57±0.79 b 386.31±9.31 a 3 ibudoosho 228.29±342.21 a 0.04±0.04 a 10.71±0.76 b 317.00±9.59 a www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 13 published by scholink inc. 4 irewolede 73.83±18.31 a 0.05±0.03 a 11.00±0.00 b 299.43±7.19 a 5 oluwaseun 43.88±28.54 a 0.03±0.03 a 12.00±1.85 b 344.24±10.79 a 6 odookun -5.00±0.00 a 983.60±33.86 b 7 eyenkorin 119.33±11.00 a 0.01±0.00 a 10.33±0.52±0.52 b 1153.50±7.87 c 8 irelopeojaoke 108.00±6.93 a 0.01±0.01 a 9.67±0.58 b 1814.67±1217.29 c 9 oluwaniagbaraemimi 71.17±24.27 a 0.03±0.02 a 11.00±0.00 b 308.92±8.46 a 10 oluwoyeamoyo 87.67±22.11 a 0.02±0.02 a 11.00±0.00 b 378.00±12.78 a 11 akerebiata 180.67±89.23 a 0.03±0.03 a 10.50±0.55 b 789.05±381.95 note. similar superscript means not significantly different (p>0.05), different superscript means significantly different (p<0.05). 5. discussion 5.1 bivariate relationship between air quality parameters the woodworking processing activities and making of furniture at sawmills include the use of many chemicals (adhesives, thinners, paints, preservatives, etc.). these release of chemicals such as vocs into the ambient air, hence increasing the levels of concentration of photochemical oxidants. specifically, the pearson’s correlation coefficient for air quality parameter as shown in table 1 revealed more precisely the nature and strength of bivariate relationship among the sample variables. it seems that there is a remarkable strong positive correlation among pm10 concentration and pm2.5 (0.99, p<0.01) and carbondioxide (co) (0.37, p<0.01) concentrations between oxygen (o2) concentration and volatile organic compounds (voc) concentration (0.34, p<0.01) among the concentration of pm2.5 and carbondioxide (co) concentration (0.38, p<0.01) between the concentration of formaldehyde (hcho) and pm10 (0.44, p<0.01) and pm2.5 (0.44, p<0.01) concentration between elevation and carbondioxide concentration (0.37, p<0.01) respectively. this outcome is in line with highly remarkable values recorded by raimi et al. (2018) in their studies on “assessment of air quality indices and its health impacts in ilorin metropolis, kwara state, nigeria”. this outcome indicates that as pm10 in sawmill environment increases, pm2.5 increases significantly, as formaldehyde (hcho) increases pm10 and pm2.5 increases significantly, as oxygen (o2) increases volatile organic compound (voc) increases, as carbondioxide (co) increases pm10 and pm2.5 concentration increases. this may be due of reaction of pollutants or planetary boundaries interplay. similarly, there exists remarkable positive correlation among formaldehyde (hcho) concentration and temperature (0.35, p<0.05) and oxygen (0.26, p<0.05) concentrations. however, there was a significantly negative correlation between carbondioxide (co) www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 14 published by scholink inc. concentration and volatile organic compound (voc) concentration (p<0.01) and between oxygen (o2) concentration and carbondioxide (co) (p<0.01), between combustible (lel) concentration and temperature (p<0.05), and between elevation and volatile organic compound (voc) (p<0.01) concentration. this implies that, as volatile organic compound (voc) and oxygen concentration increases, carbondioxide (co) decreases considerably, as temperature increases combustible (lel) concentration decreases significantly and as voc concentration increases elevation decreases significantly. this may be attributed to the toxic nature of these pollutants. 5.2 comparison of air quality with the recommended acceptable standards the most significant part of monitoring inventory of emission is to ensure its validation with the ambient air quality data. practically, the situation is impossible to accurately appraise emissions from all sources in an area, especially where sources change over time and in space, because emission inventories are constructed on the basis of different assumptions as well as missing data projections. the availability of primary data is every year and it is for these records to reflect the time dynamics as well as space. statistically, emissions validation using obtained concentrations with acceptable standards and models. however, it must be borne in mind that the formulation of air quality models are themselves based on atmospheric processes assumptions. the best qualitative technique for estimating emissions is to liken their trend through the concentrations observed from a ten-year study such as the current study. raimi et al. (2018) attempted to validate emissions from industrial site of temidire irewolede community (tic) for a period of eight weeks at twenty-four (24) locations using data of air quality monitoring sampling stations in kwara state. in the current study, estimates of emission and concentrations of carbon monoxide (co), particulate matter (pm2.5), particulate matter (pm10), volatile organic compound (voc), combustible (lel), formaldehyde, oxygen (o2), temperature (o0c) and relative humidity (rh) in the study area are compared with same pollutants as the acceptable standards recommended at monitoring station, for the period of two months. the oxygen analysis found in the study area was non remarkable from that of fmev standard but was well remarkably below that of the who standard. this result is consistent with the report by raimi et al. (2018) which indicates that the level of oxygen found in the study area did not differ remarkably from that of fmev standard (p=0.075, p>0.05) but remarkably above that of who standard (p<0.0001). however, this current study show oxygen level is above the recorded oxygen level reported by raimi et al. (2018). the results also showed that the level of combustible (lel) was significantly lower than that of who acceptable value but not significantly different from that of fmev standard. such findings confirm the results of qualitative and quantitative analysis results, indicating that vocs level are twice as high as the fmev and who standard. the elevated vocs presented in these studies, especially in terms of occupational health of workers in the sawmill is alarming, although consistent with findings of results obtained from previous works (bean & butcher, 2006). elevated concentration levels of vocs could lead to respiratory problems and may cause distress to asthmatics among industrial workers. this finding agrees with highly significant values reported by raimi et al. (2018) www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 15 published by scholink inc. based on their studies on assessment of air quality indices and its health impacts in ilorin metropolis, kwara state, nigeria. this can be explained by a wide range of finely divided solids that may be dispersed into air from combustion process and sawmill activities at the sawmill environment, industrial activities or natural sources. the significant difference in the level of urbanization, or the significant difference in physiographic characteristics could also be attributed to saw mill sources as well as planned burns and it could be referenced against known events (raimi, 2008; raimi et al., 2018). likewise, regardless of the homogeneity of outcomes from these sawmill despite its configuration, may have been influenced by the intrinsic deterministic nature. these vocs react with primary anthropogenic pollutants especially, nox, so2 and anthropogenic organic carbon compounds-to produce haze of secondary pollutants (janice, 2002; raimi et al., 2018). the mean concentration of voc in the air of the sawmill environment is 4.87. this is higher than the mean value of 1.20 reported by raimi et al. (2018) in their study. this could be attributed to tree filing, soot and smoke from the sawmill environment and therefore poses a problem to the health of the residents and people in the area and also to environmental sustainability. this finding corroborate with highly significant values recorded by tawari and abowei (2012) and raimi et al. (2018) in their studies. the actual health damage caused by dust particles depends upon its nature and composition. the result also shows that the level of combustible (lel) was significantly less than that of who acceptable value but not significantly different from that of fmev standard. similar studies support the qualitative and quantitative analysis results, indicating the level of voc was significantly above that of fmev standard and that of who standard. the elevated vocs as shown in this results especially in terms of occupational health of workers in the sawmill is worrisome, although consistent with results obtained from previous works (bean & butcher, 2006). elevated concentration levels of vocs could lead to respiratory problems and may cause distress to asthmatics among workers in the industry. this finding agrees with highly significant values recorded by raimi et al. (2018) in their studies on assessment of air quality indices and its health impacts in ilorin metropolis, kwara state, nigeria. this can be explained by a wide range of finely divided solids that may be dispersed into air from combustion process and sawmill activities at the sawmill environment, industrial activities or natural sources.the significant difference in the level of urbanization, or the significant difference in physiographic characteristics could also be attributed to saw mill sources as well as planned burns and it could be referenced against known events (raimi, 2008; raimi et al., 2018). moreover, the homogeneity of outcomes from these sawmill despite its configuration, may have been influenced by the intrinsic deterministic nature. these vocs react with primary anthropogenic pollutants specifically, nox, so2 and anthropogenic organic carbon compounds-to produce haze of secondary pollutants (janice, 2002; raimi et al., 2018). the mean concentration of voc in the air of the sawmill environment is 4.87. this is higher than the mean value of 1.20 given by raimi et al. (2018) in their study. this could be attributed to tree filling, soot and smoke from the sawmill environment and therefore poses a problem to the health of the residents and people in the area and also to environmental www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 16 published by scholink inc. sustainability. this finding corroborate with highly significant values recorded by tawari and abowei (2012) and raimi et al. (2018) in their studies. the actual health damage caused by dust particles depends upon its nature and composition. according to the indian health care institute, the number of patients with respiratory problems in delhi hospitals is alarming (indian express, 1996). in addition, the mean concentrations of pm2.5 and pm10 in the studied samples were 91.71 and 107.78 respectively. this is worth more than the mean value of 64.58 and 43.22 given by raimi et al. (2018) in their study. this situation is expected to have adverse implications on the health performance of employees in the sawmill. prolonged exposure to high concentration levels of pm10 may cause throat and lung irritation, bronchitis and possibly premature death (karr et al., 2007). however, the results of this study contradict the above findings and pm2.5 and pm10 were both significantly lower than fmev standards and respectively higher than who standards, thus the air has met the “low health category” considering the fmev standards and posing no threat to the health and environment. this means that the levels of pm2.5 and pm10 particles in the air can be considered healthy for the resident of the sawmill communities and everyone. however, both pm2.5 and pm10 are respectively higher than who standards, thus could results in a call to public health action and should be given utmost attention because the present concentration could be due to anthropogenic activities of the sawmill industry present in the study area. similarly, according to benjamin d. horne “long-term chronically elevated levels of ambient fine particulate matter (pm2.5) air pollution such as those seen in major population centers across the globe are associated with the development of chronic respiratory, cardiovascular and other diseases, as well as death due to these conditions. chronically high pm2.5 pollutions is also linked to death due to acute lower respiratory infections (alri), including pneumonia and influenza. in geographic regions where pm2.5 pollution levels are, on average, relatively low but where large short-term acute increases can occur, a dose-response relationship has been observed between acute pm2.5 elevation and regional epidemics of alri manifesting as bronchiolitis, influenza and pneumonia in children and adults”. the concentration of pm2.5 and pm10 measured seem highly significant and cumulative effect might be harmful to health. interestingly, the sources of particulate matter can be manmade or natural. some particulates occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation and sea spray. human activities, such as the burning of fossil fuels in vehicles, power plantsand various industrial processes alsogenerate significant amounts of aerosols. averaged over the globe, anthropogenic aerosolsthose made by human activitiescurrently account for about 10% of the total amount of aerosols in our atmosphere. elevatedlevels of fine particles in the air are linked to health hazards such as heart disease (molles, 2005; raimi et al., 2018) altered lung function and lung cancer. persistent free radicals connected to airborne fine particles could cause cardiopulmonary disease (bronwen, 1999; raimi et al., 2018). although, the measured concentrations of co in air around the saw mills investigated were below the instrument detection limit. carbon monoxide in air is the product of incomplete combustion, which is primarily released from the emissions of vehicles and generators. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 17 published by scholink inc. although, it sources is not solely from the exhaust of the operating power generating set, since air current may contain intractable concentration from diffuse sources. carbon monoxide values were expected to be high due to high traffic flow and continuous releases of vehicular emissions in around most of the saw mills. although the measured concentration levels of co were well below the set fmenv ambient air limits of 10 ppm, atmospheric co is of concern because of its obvious human health and climatic effects. this is because most of the saw mills are located within residential and commercial areas. carbon monoxide inhalation causes muscular reflexes, impairs thinking and causes drowsiness by reducing the oxygen carrying capacity of the blood. it is also associated with increase in the likelihood of exercise related pain in people with coronary heart disease. co is a known neurotoxin, and there is a potential for chronic exposure to exert neurologic effects. furthermore, it has been associated with effects on prenatal and early postnatal mortality and low growth in children of women exposed during pregnancy. these effects are presumably due to oxygen deprivation. 5.3 comparison of the air quality parameters in spite of variances in time and location, there are limited statistically remarkable differences in temperature levels of (odookun), vocs (oluwaniagbaraemimi, asadam, irewolede), co (eyenkorin, irelopeojaoke) and elevation (eyenkonrin, irelopeojaoke), etc. geographic analyses suggest systematic differences in exposure by community. for instance, voc levels are higher in oluwaniagbaraemimi, asadam, irewolede area were significantly higher than that obtained in other locations (p<0.05). this concentration in this study was higher than the value reported by raimi et al. (2018) for temidere irewolede community (tic) (1.20µg/m3). in ilorin metropolis, kwara state, nigeria. the finding of the present study is indicating that, there is a spatial variation of voc concentration over the selected study sites and co results obtained from the present study revealed that there is a spatial (site to site) variation of co concentration even though the overall concentration trend of co concentration in eyenkorin and irelopeojaoke reported significant higher level of co compared with other saw mills locations (p<0.05), this sawmill happened to be one of the very busiest route and business center and state cross bus station and could be due to the indirectly increased vehicle congestion around eyenkorin and irelopeojaoke. the high values of co obtained around eyenkorin and irelopeojaoke sawmill were not surprising considering the volume of fossil fuels consumed on daily basis to power different equipment, added to the disposal of sawdust and other wood wastes by open incineration. these activities emit many gaseous pollutants including co that may cause irritation of respiratory tracts and lungs, adversely affect workers defence system against pathogens and elevate the risk of respiratory tract infections (akunne et al., 2006). many researchers also reported that air pollution due to wood burning was positively associated with hospital emergency visits for pneumonia (ozdilek, 2006; peel et al., 2005). a mechanistic theory consistent with the findings of this study holds that the development of respiratory symptoms, preterm births, increased use of asthma medication and reduced lung function (hertz-picciotto et al., 2007; ritz et al., 2007; molitor et al., 2007; jarrett et al., 2005) may be associated with the high value obtained on psi (pollutant standard index) which described the www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 18 published by scholink inc. ambient air quality at eyenkorin and irelopeojaoke sawmill as unhealthful. models of exposure based on both activity patterns and ambient monitoring show that low-income and vulnerable groupsincluding children are exposed to the highest levels of vocs, co and particulates in oluwaniagbaraemimi, asadam, irewolede, eyenkorin, irelopeojaoke. also higher temperature was experience in odookun saw mill and was significantly higher than that obtained in other locations. although, temperature has been rising on average, in the world and can be used as a surrogate for the meteorological factors influencing surface ozone formation (camalier et al., 2007). our results suggest a trend of increasing temperatures and these rising temperatures have the potential to cause thousands of deaths and cost billions of naira. temperature and humidity have been well known to be predictors of death and are an important factor in the analyses and this temperature change is greater than that seen in other saw mills. this variant suggests a long-term adaptation to the local climate, and underlines the importance of careful site-specific adjustment for temperature while assessing the effects of other environmental concerns such as air pollution. similarly, higher elevation was reported at eyenkorin, irewolopeojaoke and were significantly higher than that of other locations (p<0.05). the level of lel in odo-okun was remarkably less than that obtained in other locations (p<0.05). 6. conclusion the eye smarting at sawmill is annoying even if it has not been shown that it is likely to damaged health. certainly, air pollution naturally disrupts the ordinary business and pleasure of life, given reasons enough for the vigour of the complaints and at the present time, there is a vital question around air quality that people inhale individually in sawmills and several snags that its pollution would cause on the public health (respiratory, pulmonary and cardiovascular diseases, increase of infections) and on the environment (destruction of the ozone layer, global warming, climatic catastrophes). it can be concluded that the average concentrations of co, o2 and other measured parameters such as formaldehyde (hcho) etc are generally lower and within tolerable range of national and international regulatory standards for air quality indices. however, there are some exceptions such as the average concentrations of volatile organic compounds (vocs), pm2.5, pm10 and combustible (lel) respectively high compared to national and international standards. this high value is associated with the amount of pollutant present in the sawmill air due to influents of input from the activities of sawmill. hence, ilorin metropolis air pollution were however found to be polluted. as a result, it is concluded that far-reaching efforts must be made to reduce air pollution levels around the sawmill environment. decreasing air pollution saves and advances quality of lives. it can help reduce the risk of acute and chronic respiratory infections such as pneumonia and asthma between vulnerable and sensitive groups including children. reducing air pollution will reduce complications during pregnancy and childbirth for the resident of the sawmill communities, as well as advance development of the community, aiding them to live longer and more productive lives, as well as benefit sustainable development and climate change mitigation. the dearth of accurate information on the diverse sources www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 19 published by scholink inc. of pollution, the pollution state and degree at sawmills, by the government or municipal authorities and policymakers could lead to sort of commitments to limit air pollution in the country and made the occurrence of pollution from persisting. 7. recommendations by and large, this study can serve as an important tool to support pollutants in monitoring concentration, i.e., environmental pollution. however, characteristics that affect individual health, neighbourhood, community, or even national level. subsequently, research methods, as well as intervention strategies, differ across the spectrum from individual to national levels of organization. to advance on the current air quality monitoring and assessment programmes in sawmill environment, recommendations were advanced with respect of the several levels of interaction to embark on the following: i. improving saw mill monitoring and modelling of air quality: levels of pollutant can both vary horizontally and vertically, especially in saw mill settings. combined with the requirement to enhanced characterize concentrations of pollutant and exposures in saw mill environments, access to these facts should be available to communities, researchers, and decision makers. just as important as the types of statistics collected are the target locations for monitoring pollution at saw mill. up-to-date monitoring sites are not constantly located to make known saw mill inequities. for most part there is inadequate spatial and time-based feature to answer exposure associated questions in saw mill environments. current monitoring sites may or may not contain hot spots and represent the entire exposed area. distribution modelling can be used to recognize where these monitors may best be located, but a large number of monitors is needed to guarantee that high concentration areas are found. currently hot spots are determine by air quality data alone. air pollution siting and monitors should include site selection in terms of health hot spots and proximity to facilities and intersections of concern that may increase exposures. expansion and improved existing target of air-monitoring systems will require concerted effort of local, state, and federal agencies and participation in educational and community interests. ii. exposure target assessment: detail all-inclusive report of actual urban populations exposures will significantly increase the ability to characterize the risks of ambient concentrations. for example, the usage and development of further unreceptive dosimeters will make available a non-invasive monitoring means of voc and further hap exposures that is equally easy and practical. because of its ease of usage, monitors that are passive are an outstanding instrument for direct engagement of communities in monitoring the ambient concentrations and individual exposures. in addition, through an improved description of saw mill exposures, more research are needed into the subsequent mechanisms of assessment exposure in saw mill settings: time-activity outlines in specific community settings, www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 20 published by scholink inc. microscale disparities in ambient concentrations of haps focus on local sources, lessons are required through vertical and horizontal gradients in focus over insignificant spatial scales, improved air quality emissions standards, including both emissions factors and geographic information, or procedures to identify specifying locations in the context of small distribution sources, procedures and models for efficient use of data sets for community-based source inventory which must be established. iii. interdisciplinary adoption of method to data collection and analysis: current data sources from other section can be used to learn more about health differences among saw mill inhabitants. there are important sources of valuable information for secondary usage which remain available from the administrative registration systems, including key information events registries, hospital admissions, which can also contribute to our understanding of inequities in urban health. an interdisciplinary method is needed to analyses available data. health services should play a more significant role in analyzing and using air quality data, and annual air quality reports should be obtained at public meetings organized by appropriate health and environmental agencies. community environmental health advisory committee should be set up, trained and educated to communicate and to monitor this ongoing effort with communities particularly resident of saw mill. air pollution data can be collected in a much more informative way through an interdisciplinary approach. one example is by intensifying the usage of geographic information systems technology to construct aerial monitoring databases. information on air pollutant levels and traffic patterns can be covered by data on other risk factors such as specific pollution sources, crowding, and poverty. current nature of pollution models can be broadened with a biopsychosocial model (characterizes the nested, interactive ecology of biology, mental function, and social status and relations in a range of human pathologies) by incorporating elements derived from the various administrative data tools available from government agencies, using the latest tools available to the public and community ecology. these information range from demographic data to housing inspection information, and other emergency services. iv. promote alertness of the harm pollutants cause communities and residents of the sawmill on vulnerable and sensitive groups like children, pregnant women and the elderly. v. develop monitoring enforcement measures, tools and regulations. vi. institute policies planning to reduce pollution that can be caused by future development. agencies of government such as the kwara state ministry of environment should work in partnership with other development partners, i.e., multinationals and stakeholders in management of air pollution to come up with an all-inclusive air quality management (aqm) outline for the state. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 21 published by scholink inc. vii. health warning must keenly be disseminated by state and local government to the resident of the sawmill and its surrounding communities so that they can better enhanced and protect themselves from air pollution. competing interests we declare that we have no conflict of interest that could be perceived as prejudicing the impartiality of the research reported. this research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. consent all authors declare that ‘written informed consent was obtained from the participants. ethical approval ethical approval for the study was sought and gotten from the institutional review board of the kwara state university. permission to carry out the research as well as written consent was also obtained from all the sawmills owners and operators after explaining the purpose of the study to them. references anavberokhai, i. o. 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(1996). particles in our air: concentrations and health effects. boston, ma: harvard university press. energy and earth science vol. 7, no. 2, 2024 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 40 original paper study on removal methods of heavy metals from marine freshwater products chen junhao 1 & chen guiqing 1 1 jinan university, guangzhou 510630, china received: november 5, 2024 accepted: november 15, 2024 online published: january 7, 2025 doi:10.22158/ees.v7n2p40 url: http://dx.doi.org/10.22158/ees.v7n2p40 abstract nowadays, marine rivers are seriously polluted, and heavy metals such as arsenic, cadmium, mercury, lead, chromium and copper are absorbed by marine freshwater organisms, seriously endangering human health. after boiling marine river products such as scallop skirt into a concentrated liquid and adding sodium carbonate na2co3, most heavy metals will precipitate under strong alkaline conditions and be removed by filtration. but it doesn't work on tin sn. adding calcium hydroxide ca(oh)2, the heavy metal forms a precipitate under strong alkaline conditions. it’s filtered out. citric acid or calcium citrate are strong chelating agents that can form chelating precipitates with heavy metals and be removed by filtration. the combination of the above two is better. filtration loss can be reduced if hydrolysis is performed first! keywords marine science, seafood juice, scallops, alkali, calcium hydroxide, sodium carbonate 1. introduction the world pollution is more and more serious, since china’s reform and opening up 40 years of rapid economic development pollution even more serious! marine rivers are polluted, and heavy metals such as arsenic, cadmium, mercury, lead, chromium and copper are absorbed by marine freshwater organisms. cadmium is easily enriched in crustaceans, kelp, seaweed and nori, which seriously endangers human health. according to guangdong-domestic and international reports: pearl river estuary oyster copper 100 times over the standard. according to zhihu.com, the pass rate of sea crabs sampled by the state is only 20%. according to our detection: shandong laizhou scallop skirt cadmium content reached 15-34 times of the standard. arsenic levels in laver in lianyungang, jiangsu province, were 20 times higher www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 41 published by scholink inc. than the legal limit. lianyungang, a large laver processing business owner unexpectedly did not know that laver also test heavy metals. such a serious problem has not yet attracted enough attention from the relevant departments! 2. materials, equipment and methods boil the skirt of laizhou scallop into concentrated liquid, precipitate and filter. detection results (mg/kg): 1# cd=1.4, 2# cd=2.7, 3# cd=4.4, 4# cd=7.3 and 5# cd=17. both exceed national standards. methods of removing heavy metals are now investigated using 3# and 5# samples (figures 1 and 2). 2.1 devices 2.1.1 the precipitation method, precipitation-chelation method and chelation-precipitation method use a 5l triangular cone bottle and 1500w temperature control furnace. 2.1.2 hydrolyzation-chelation-precipitation method requires hydrolysis equipment. 2.1.2.1 reflux hydrolysis. with a 5l triangular cone bottle, plus a rubber plug, plug in the condensation tube, and connect the tap water to cool the hydrolyzed steam, so as not to burn the hydrolysate dry. it was heated in a temperature controlled electric furnace and hydrolyzed at 100 0 c at one atmospheric pressure (1kg pressure) for 12 hours. take care to regulate the temperature to prevent excessive boiling and dry the hydrolysate liquid. 2.1.2.2 reactor hydrolysis. use 304 stainless steel reactor, volume according to need. with an anchor mixer. run the mixer for 10 minutes at regular intervals at 40 rpm. be careful not to fill the reactor too full, 70% can be. hydrolysis at 2kg pressure, 112-118 0 c for 12 hours. be careful not to heat too much to avoid a burnt taste. 2.2 citric acid hydrolysis the above hydrolyzed raw materials are heated and hydrolyzed with citric acid and appropriate amount of water calculated by the following formula. 2.2.1 the amount of citric acid hydrolysis can be calculated by the “double chen hydrolysis formula”: from chen junhao and chen guiqing. study on crystal structure and application of pearl and shellfish [m]; december 2018, jinan university press, p.143. m hydrolytic acid=(molecular weight of hydrolytic acid/14.0067) × raw protein content × 16%×cc÷y citric acid is a ternary acid y=3. m citric acid=(192.125÷14.0067) × (weight of raw material × protein content of the raw material) × 16% × cc ÷ 3 =weight of raw material × protein content of raw material × cc × 0.7315=weight of raw material × nitrogen content of raw material × 6.25 × cc × 0.7315...... ⑴. add the same amount of water, heat to hydrolysis. m stands for weight. select cc refer to table 1. 2.2.2 neutralization of food-grade hydrated lime. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 42 published by scholink inc. from the inorganic chemistry textbook. m calcium hydroxide=(222.284÷384.251) × m citric acid=0.5785×m citric acid... the essay in order to prevent residual calcium hydrogen citrate cah(c6h5o7) and calcium hydrogen citrate cah4(c6h5o7)2 from being converted into calcium citrate ca3(c6h5o7)2 precipitation, and to completely remove heavy metals, so that the hydrolysate reaches ph12-13, the addition of hydrated lime requires an increase of 5% of the original amount. since the saturated solubility of hydrated lime ca(0h)2 at 20 0 c is 0.16(g/100g), ph12-13 is reached at this time. excess lime can be precipitated and filtered out, and the saturated solubility of lime in the solution of 0.16g/100g will not affect the subsequent treatment. 2.2.3 after 5 hours of precipitation, filter. 2.2.4 expected production v (volume). from chen junhao, chen guiqing. crystal structure and application of pearls and shellfish [m]. december 2018, jinan university press, p.147. product volume v(ml)=raw material weight (g) × protein content of the raw material %×16%×γ ÷ amino nitrogen of the product (g/ml)...... (3) 2.2.5 extraction rate γ: reactor hydrolysis γ=50% ~ 70%, reflux hydrolysis temperature is greatly affected by temperature, worse in winter, γ=30% ~ 50%. the hydrolysis capacity of citric acid is weaker than that of hydrochloric acid, and it is more suitable for hydrolysis of seafood with protein content below 30%. 3. experimental methods 3.1 precipitation method 3.1.1 after adding sodium carbonate na2co3 to seafood liquid, most heavy metals will precipitate under strong alkaline conditions, such as cahaso4∙h2o, cacro4, cdco3, hg2co3, pbco3, znco3, nico3, cuco3, and then filter out. but it doesn’t work on tin sn. 3.1.2 after adding hydrated lime ca(oh)2 to seafood liquid, all heavy metals will precipitate under strong alkaline conditions, such as: ca5(aso4)3∙oh, ca4(oh)2(aso4)2, cd(oh)2, cd(oh)3, cr(oh)2, cr(oh)3, cu(oh)2, hg2(oh)2, ni(oh)2, ca5 (aso4)3∙ oh, ca4 (oh)2(aso4)2, cd (oh)2, cr(oh)3, cu(oh)2, hg2 (oh)2, ni(oh)2, pb(oh)2, pb(oh)4, sn(oh)2, sn(oh)4, zn(oh)2. filter out. 3.2 precipitation-chelation after the removal of heavy metals, the seafood juice is strongly alkaline, not delicious, and cannot measure amino acids, and must be adjusted to weak acidity. the use of hydrated lime precipitates, which must be regulated with citric acid, forms calcium citrate and heavy metal precipitates, which are filtered out. this is precipitation-chelation, not precipitation anymore. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 43 published by scholink inc. 3.3 chelation-precipitation method citric acid is a strong chelating agent, able to chelate heavy metals. calcium citrate and heavy metal precipitates are formed by adding hydrated lime, and heavy metals are removed by filtering and discarding residue after a long time precipitation. 3.4 hydrolyzation-chelation-precipitation method protein is a large molecule, filtration loss. first, the protein is hydrolyzed into soluble amino acids with citric acid, and the hydrated lime is added to form calcium citrate and heavy metal precipitates, which are filtered and removed to reduce losses. 4. experimental results 4.1 precipitation method sodium carbonate is not a base, classified as salt, called alkaline substances, alkaline weak. 4.1.1 scallop solution 100ml+ 7% sodium carbonate + 18ml water, dissolved by stirring, ph≈9. precipitate for 48 hours and filter. test results are shown in figure 3, cd=0.89. 4.1.2 scallop liquid 250ml+ 10% sodium carbonate + 25ml water, stir to dissolve, ph>9. precipitate for 72 hours and filter. test results are shown in figure 4, cd=0.71. 4.1.3 scallop liquid 250ml+ sodium carbonate 15%+ water 38ml, dissolved by stirring, ph≈10. precipitate for 72 hours and filter. test results are shown in figure 5, cd=0.72. * using more than 9% sodium carbonate does not improve results. all cd˃0.5, not up to standard. 4.2 precipitation-chelation method 4.2.1 scallop liquid 300ml+ 2% hydrated lime, stir to dissolve, ph=12. precipitate for 24 hours, add citric acid to ph=8. chelate, precipitate for 36 hours, filter. test results are shown in figure 6, cd=0.39. 4.2.2 scallop liquid 350ml+ hydrated lime 2.5%, stir to dissolve, ph=12. precipitate for 24 hours, add citric acid to ph=8. chelate, precipitate for 36 hours, filter. test results are shown in figure 7, cd=0.34. 4.3 chelation-precipitation method 4.3.1 scallop liquid 560ml+ 6% citric acid, stir to dissolve, ph=3. reaction for 12 hours, add hydrated lime to ph=12. precipitate for 12 hours and filter. the test results are shown in figure 8, cd=0.21. 4.3.2 scallop liquid 560ml+ 6% citric acid, stir to dissolve, ph=3. reaction for 12 hours, add hydrated lime to ph=12. precipitate for 48 hours and filter. test results are shown in fig. 9, cd=0.21. 12 hours of precipitation is enough. 4.3.3 scallop solution 100ml+ citric acid 6%, stir to dissolve, ph=3. reaction for 12 hours, add hydrated lime to ph=12. precipitate for 14 hours. the filtering methods are as follows: 4.3.3.1 filter paper filtering. test results are shown in fig. 10, cd=0.44. 4.3.3.2 1 micron filter filter. test are shown in fig.11, cd=0.4. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 44 published by scholink inc. 4.3.3.3 0.5 micron filter filter. test results are shown in fig. 12, cd=0.28. 4.4 hydrolyzation-chelation-precipitation method 4.4.1 scallop liquid 2120ml+ citric acid 426.5g+ water 1600ml. hydrolysis for 12 hours, hydrated lime neutralization and other treatment after precipitation for 12 hours, filtration. test results as shown in fig. 13, cd<0.02, as1.2, pb0.0600, hg<0.05, cr0.21, cu<0.05; precipitate for 48 hours and filter. test results are shown in figure 14, as 0.60; precipitate for 60 hours and filter. test results as shown in fig.15, as 0.48, inorganic arsenic 0.15, cd 0.0040. 4.4.2 scallop liquid 1695ml+ citric acid 337.3g+ water 1600ml. hydrolysis for 12 hours, hydrated lime neutralization and other treatment after precipitation for 24 hours, filtration. test results as shown in fig. 16, cd 0.020, inorganic arsenic 0.15. 4.4.3 scallop liquid 1680 ml+ citric acid 330g+ water 1600ml. hydrolysis for 12 hours, hydrated lime neutralization and other treatment after precipitation for 3 hours, filtration. test results as shown in fig. 17, cd0.079, inorganic as was not detected, pb 0.0370, hg was not detected, cr 0.42. precipitate for 6 hours and filter. test results as shown in fig. 18, cd 0.078, inorganic as was not detected, pb was not detected, hg was not detected, cr0.42. precipitate for 9 hours and filter. test results as shown in fig. 19, cd0.077, inorganic as was not detected, pb 0.0284, hg was not detected, cr 0.33. precipitate for 12 hours and filter. test results as shown in fig. 20, cd 0.072, inorganic arsenic as 0.041, pb 0.0373, hg 0.011, cr 0.43. 3 hours of precipitation is enough. 4.4.4 scallop liquid 2100ml+ citric acid 499g+ water 1200ml. hydrolysis for 12 hours, hydrated lime neutralization and other treatment after precipitation for 12 hours, filtration. test results as shown in figure 21, cr 830.93μg/l, cu 116.44μg/l, inorganic arsenic 0.36mg/kg, cd0.86μg/l, hg 0.34μg/l, pb 8.93μg/l. 4.4.5 experimental laver. total amino acid 32.5%. test results as shown in figure 22, total arsenic 20, total mercury 0.010, cadmium 0.77, chromium 0.93, copper 13.5, lead 0.508. 4.4.6 laver seasoning liquid. 180g dried laver + 258g citric acid + 1600ml water. cc=7, hydrolysis 12 hours, hydrated lime neutralization and other treatment after precipitation 12 hours, test results as shown in fig. 23 shows lead < 0.05, total arsenic 0.38, total mercury < 0.05, cadmium < 0.02, chromium < 0.1, copper < 0.5. 4.4.7 nori 84g+ citric acid 159.8g+1680ml water. cc=8. hydrolysis for 12 hours, hydrated lime neutralization and other treatment after precipitation for 12 hours, filtration. test results as shown in figure 24, cr 92.16μg/l, cu 130.92μg/l, inorganic arsenic 0.46mg/kg, cd 21μg/l, hg 0.12μg/l, pb 4.34μg/l. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 45 published by scholink inc. 5. conclusion 1) it is not possible to remove heavy metals by simple precipitation method, because it is strongly alkaline and must be adjusted to weak acidity to make food, which is no longer a precipitation method. 2) precipitation-chelation or chelation-precipitation method is feasible to remove heavy metals, the latter effect is better! 3) hydrolyzation-chelation-precipitation method is the most effective method to remove heavy metals, with less filtration loss, and can directly produce amino acids to make seafood condiments and complex seasonings. the book is illustrated table 1. 3# scallop liquid table 2. 5# scallop liquid table 3. 7% of edible alkali, precipitated 48 hours table 4. 10% of edible alkali, precipitated 72 hours table 5. edible alkali 15%, precipitation 72 hours table 6. hydrated lime 2%+ citric acid, precipitation 36 hours table 7 hydrated lime 2.5%+ citric acid, precipitated for 36hours table 8 citric acid 6%+ hydrated lime, precipitated for 12hours www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 46 published by scholink inc. table 9. 6% citric acid + hydrated lime, precipitated for 48hours table 10. 6% citric acid + hydrated lime, precipitated for 14hours table 11. citric acid 6% + hydrated lime, precipitated for 14 hours table 12. citric acid 6% + hydrated lime, precipitated for 14 hours, 1 filter membrane filtrationr 0.5 filter membrane filtrationr table 13. scallop hydrolyzed juice , precipitated for 12hours table 14. scallop hydrolyzed juice , precipitated for 48hours table 15. scallop hydrolyzed juice, precipitated for 60hours table 16. scallop hydrolyzed juice, precipitated for 24hours www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 47 published by scholink inc. table 17. scallop hydrolyzed juice, precipitated for 3 hours table 18. scallop hydrolyzed juice, precipitated for 6 hours table 19. scallop hydrolyzed juice, precipitated for 9hours table 20. scallop hydrolyzed juice, precipitated for 12hours table 21. scallop hydrolyzed juice, precipitated for 12hours table 22. laver www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 48 published by scholink inc. table 23. laver seasoning solution table 24. new laver hydrolyzed juice gly 甘氨酸。ala 丙氨酸。val 缬氨酸。leu 亮氨酸。ile 异亮氨酸。phe 苯丙氨酸。trp 色氨 酸。 tyr 酪氨酸。asp 天冬氨酸。his 组氨酸。asn 天冬酰胺。glu 谷氨酸。lys 赖氨酸。gln 谷氨 酰胺 met 甲硫氨酸。arg 精氨酸。ser 丝氨酸。thr 苏氨酸。cys 半胱氨酸。pro 脯氨酸。 references chen junhao, & chen guiqing. (2017). production method of amino acid liquid of pearl oyster or ginseng of pearl oyster. patent no. zl 2015 1 057130.x. authorization date november 21, 2017. chen junhao, & chen guiqing. (2017). production method of fresh scallop juice. patent no. zl 2015 1 0571208.3. authorization date november 21, 2017. chen junhao, & chen guiqing. (2018). crystal structure and application exploration of pearls and shellfish. jinan university press, december 2018. chen junhao, & chen guiqing. (2019). the ancient shells were sdudied by x-ray diffraction and electron probes. journal of water resources and ocean science, 8(6), 86. https://doi.org/10.11648/j.wros.20190806.11 chen, g. q., & chen, j. h. (2018). production method of astaxanthin prawn juice. patent no. zl 2015 1 0571551.8. authorization date: january 2, 2018. hu jing et al. (2017). response surface method optimization of removal process of cadmium from mushroom by citric acid. food science, 38(14). wu yanan et al. (2017). effect of cadmium removal of citric acid on structure and physicochemical properties of brown rice flour. china journal of grain and oil, 32(8). https://doi.org/10.11648/j.wros.20190806.11 energy and earth science vol. 3, no. 2, 2020 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 original paper after the sun: energy use in blue v. green water for agriculture jenny r. kehl 1 1 global water security scholar for the university of wisconsin, office of the provost, global studies, and school of freshwater sciences, milwaukee, wisconsin, usa received: may 29, 2020 accepted: june 8, 2020 online published: july 6, 2020 doi:10.22158/ees.v3n2p1 url: http://dx.doi.org/10.22158/ees.v3n2p1 abstract the purpose of this article is to highlight the difference in energy consumption between using blue water versus green water for agriculture in areas where water-intensive crops are grown in water-scarce regions. it focuses on water and energy consumption for greening the desert in united states, the world’s largest grain producer. the analysis is limited to the three largest crops by volume and value; corn, cotton, and wheat, which generate billions of dollars for the economy and use billions of gallons of water each day. the primary methodology is to use geographic information systems (gis) to visually represent the comparative amounts of blue water and green water used to grow water-intensive crops in water-scarce regions, by statistically mapping levels of water stress overlaid with the amounts of blue water versus green water used. it exposes where energy-intensive water practices are occurring due to a high dependence on blue water for irrigation in agriculture. the article concludes by discussing strategies to improve energy efficiency and reduce the vulnerabilities associated with overdependence on blue water such as high energy costs, low energy security, and susceptibility to aquifer reduction and ground water depletion. keywords energy security, water use efficiency, agriculture, sustainable development 1. introduction energy is an integral part of providing water for food security. after the sun, which is the greatest source of energy for growing plants for food, substantial amounts of additional energy are needed to irrigate, produce, harvest, process and transport agricultural crops to support a burgeoning population. most of the additional energy used in agriculture is for irrigation, which requires large amounts of energy to pump vast amounts of water from long distances or great depths. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 2 published by scholink inc. agriculture is the largest water-user and second largest energy-user in the united states. approximately 300 billion gallons of freshwater are withdrawn daily, requiring energy for pumping and transporting, from surface and ground water sources for agricultural irrigation in the united states (us geological survey 2019). with such a high amount of all energy flowing to one sector, we cannot advance sustainable development without addressing the inefficiencies and interdependencies between water and energy in the agricultural sector. one of the hidden realities in this energy-water-food nexus is that there is a significant difference in the amount of energy used between blue water and green water in agriculture. blue water is the volume of freshwater used from surface and groundwater sources, green water is the volume of freshwater in the form of precipitation or stored in the soil. the difference is important because agricultural areas that use blue water are highly dependent on irrigation, which requires a tremendous amount of energy to pump, transport, deliver and disperse water. the purpose of this research is to examine the amount of energy use in blue water versus green water for agriculture. it examines two problems: 1) water-intensive crops are grown in water-scarce areas, 2) these crops require a lot of blue water, which is energy-intensive. the use of blue water for irrigating crops is energy-intensive because it involves pumping, treating, diverting, delivering and moving large volumes from great depths and across vast distances. the conclusion provides empirical evidence of where the is an imbalance in blue water versus green water consumption in the largest parts of our agricultural sector, emphasizing that blue water is highly energy-intensive, and discusses the vulnerabilities associated with overdependence on blue water such as energy insecurity and susceptibility to aquifer depletion. 2. method the methodological objectives of this research are to: 1) provide empirical evidence of the comparative amount of blue water and green water used to grow our three mega crops -corn, cotton, wheatin water-scarce regions, and, 2) to identify and provide empirical evidence of any imbalances or inefficiencies in energy consumption between blue and green water in the nexus of energy-water-food security. this research uses the three largest crops in the u.s. economy, meaning the crops with the highest production volume and highest monetary value. the largest crops by volume and value are corn, cotton, and wheat. these three major crops are all water-intensive and energy-intensive. the data sources for agricultural production are the agriculture and food statistics: charting essentials, a collection of key statistics on food security, food prices, natural resources, and other information; and the agricultural baseline database, a database, report and projection of major field crops including corn, wheat, cotton, and others, from the united states department of agriculture (usda 2020). to indicate the level of water-stress in each region, we use a ratio of water use to water availability. the primary data source for the statistical mapping of water stress is the u.s. geological survey national water information www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 3 published by scholink inc. system and it is verified and constitutes no data inconsistency (tinker, 2019) with aquastat and the u.s. drought monitor (usgs nwis 2020, aquastat 2020, usdm 2020). spatial, production, and economic data are used to locate areas where the three major crops are grown in large quantities in water stressed regions. geographic information systems (gis) maps are used to represent the data. the graduated levels of water stress are statistically mapped and then overlaid with the quantity of the commodities produced in that region. the overlay illustrates the amount of blue water and green water used. 3. result this research distinguishes between the use of blue water and green water in the analysis in order to statistically map the water footprint and indicate the difference in energy consumption. prominent water scholars hoekstra and hung note “the distinction between the blue and green water footprint is important because the hydrological, environmental, and social impacts, as well as the economic opportunity costs, of surface and groundwater use for production differ distinctively from the impacts and costs of rainwater use” (hoekstra et al., 2011, p. 45). blue water is the volume of freshwater consumed from surface and groundwater sources. green water is the volume of freshwater consumed as precipitation or stored in the soil. the difference is important to understand because areas that are dependent on blue water are more dependent on irrigation and thus highly dependent on energy for pumping and transporting water. areas dependent on blue water are also more susceptible to aquifer depletion, whereas areas that are dependent on green water are less dependent on energy consumption but more vulnerable to factors such as precipitation. the baseline water stress of the united states is mapped in figure 1, which uses geographic information systems (gis) to statistically represent water stress using water data from usgs, usdm, and usda. the indicator is a ratio; it measures water stress as the difference between water availability and water consumption. the baseline water stress map is the current level of water stress across the u.s. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 4 published by scholink inc. figure 1. baseline water stress map of the united states source: usgs https://waterdata.usgs.gov/nwis, gis kehl and olshfski. the baseline water stress map exposes one of the most consequential realities of the water-energy-food nexus: many of our largest food producing regions are growing water-intensive crops in water-scarce areas, such as the great plains, midwest, southwest, texas, and california. this reality is highly energy-intensive. these areas rely on blue water and depend on irrigation, which is energy-intensive for pumping from increasing depths and transporting from increasing distances. we can expect this reality to worsen with increasing consumptive demands and increasing environmental variability. mighty rivers such as the colorado and expansive aquifers such as the ogallala are being depleted and our dependence on blue water from these sources places heavy, expensive, and unsustainable demands on energy. the results of this analysis demonstrate that several regions have a double dilemma of growing water-intensive crops in water-scarce regions and adding the complication of a blue-green water imbalance, which greatly increases the amount of energy required to grow crops. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 5 published by scholink inc. figure 2. blue and green water for corn source: usgs https://waterdata.usgs.gov/nwis, gis kehl and olshfski. the primary result is illustrated in the case of double water inefficiency, meaning that a water-intensive crops is grown in a water-scarce region and it is grown using a blue water-green water imbalance. colorado, wyoming, utah, arizona, new mexico, and california have a double inefficiency in water use in their corn production: they grow a lot of corn in a water-stressed region and they use a lot of blue water to do it. see figure 2. there is extreme water stress and a high volume of water-intensive corn grown in nebraska and colorado. there is high water stress and large quantities of corn grown in illinois, minnesota, wisconsin, and kansas. in areas with relatively high levels of precipitation and green water, namely iowa, mississippi, indiana, ohio, and kentucky, water efficiency and energy efficiency in corn production are most balanced. these areas do not require a huge amount of additional energy (or inefficient energy consumption) as they do not have a large blue-green water imbalance. in contrast, the areas that have the double inefficiency, water scarcity and blue-green water imbalance, require a tremendous amount of additional energy to “green the desert” through pumping depleted aquifers and diverting over-extracted rivers across great distances. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 6 published by scholink inc. figure 3. blue and green water for cotton source: usgs https://waterdata.usgs.gov/nwis, gis kehl and olshfski. there is also an extreme blue-green water imbalance with extreme blue water inefficiency in growing cotton in california, texas, new mexico, arkansas and arizona. see figure 3. cotton is one of the most water-intensive crops in modern production. it is also highly energy intensive if it is grown in water scarce regions. there is extreme water stress and a high volume of cotton grown in california, arizona and texas, and high water stress and a high volume of cotton in arkansas and georgia. figure 4. blue and green water for wheat source: usgs https://waterdata.usgs.gov/nwis, gis kehl and olshfski. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 7 published by scholink inc. california and arizona show extreme water inefficiency in the use of blue water to grow wheat in the desert. there is also blue-green water inefficiency in idaho, nevada, and new mexico. see figure 4. there is extreme water stress and a high volume of wheat produced in colorado, montana, kansas, nebraska, and oklahoma. there is high to moderate water stress and high wheat production in illinois, minnesota, and indiana. the greatest problem in water inefficiency and energy inefficiency in wheat production in the u.s. is in the states that are dependent on the ogallala aquifer for water security; colorado, montana, kansas, nebraska, and oklahoma. as the ogallala aquifer gets depleted due to over-extraction, the feasibility of agricultural production will decrease due to the dependence on pumping scarce water from the rapidly depleting source, as we know, and the more hidden reality of the high cost of large amounts of energy required to pump it from greatening depths. the loss of the capacity to produce a high volume, high value mega cash crop will jeopardize the economic viability of the agricultural sector in the multi-state ogallala region, not only due to the water inefficiency but due to the interdependent and expensive energy inefficiency that is not cost effective for relatively cheap cash crops. 4. discussion it is often overlooked that agricultural practices in water-scarce regions are highly energy-intensive. the use of blue water irrigation requires immense amounts of energy to pump water from extreme depths and move water across great distances. greening the desert is a deleterious distortion that is not environmentally or economically sustainable. this research provides empirical evidence of energy inefficiency in areas where there is an imbalance in blue water versus green water use for large agricultural production, as the use of blue water is highly energy intensive. the research has provided empirical evidence that wheat, corn, and cotton, all high volume, high value, and water-intensive crops grown in water stressed areas in the u.s., demonstrate the most sever water imbalances and energy inefficiencies in the american west, southwest and great plains, the results indicate that the water imbalance and consequent energy inefficiency is particularly extreme for corn in colorado, wyoming, utah, arizona, new mexico, and california; cotton in california, texas, new mexico, arkansas and arizona; and wheat in californian and arizona, which arguably should not be growing these crops and should expedite a transition to crops better suited to the urgency of environmental sustainability and economic durability in the region. water and energy intensive crops should be grown in areas that have a comparative advantage in water availability and energy efficiency, and a sustainable balance of blue-green water consumption, which seems intuitive but is actually the opposite of the empirical reality that our most water-intensive crops are grown in our most water scarce regions. these water scarce regions are highly dependent on energy-intensive blue water, which makes them vulnerable to worsening water stress, energy costs, energy insecurity, and the depletion of the aquifers and ground water resources upon which they depend. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 8 published by scholink inc. as these areas suffer more frequent and severe droughts, which exacerbate the problems of dependence on energy-intensive blue water and rapidly depleting aquifers, this study portends a large transition of intensive agriculture to the great lakes region, the largest source of surface freshwater on the planet. great lakes regional governments, development corporations, producers and consumers are commercially advertising and marketing great lakes water to large-scale growers as an abundant and free source of freshwater to attract business. the great lakes might consider putting policies in place to manage this anticipated growth with water-efficiency in the interest of sustainable development. this study introduces the empirical reality and environmental risk, and, arguably, the emerging depravity of continuing to grow water-intensive and energy-intensive crops in highly water-stressed regions. the research has been conducted in the interest of introducing difference in the amount of blue water versus green water in large-scale agriculture in the u.s. and to expose the energy inefficiency of the high dependency on large quantities of blue water to produce water-intensive crops in water stressed regions. although this work is introductory, it can be expanded and used to prompt additional research on the difference in energy consumption of blue water and green water in agriculture. it can also be used as part of a larger initiative to restructure agriculture in the u.s. from the perspective of joint water efficiency and energy efficiency, or at least be used as justification to pursue energy efficiency and sustainable sources of energy for water-intensive agriculture. references antonelli, m., rosen, r., & sartori, m. (2012). systemic input-output computation of green and blue virtual water “flows”. water resources management, 26, 4133-4146. https://doi.org/10.1007/s11269-012-0135-9 boelens, r., & vos, j. (2012). the danger of naturalizing water policy concepts: water productivity and efficiency discourses from field irrigation to virtual water trade. agricultural water management, 108, 16-26. https://doi.org/10.1016/j.agwat.2011.06.013 copeland, c., & carter, n. (2017). energy-water nexus: the water sector’s energy use, congressional research service, crs report 7-5700 r43200. retrieved march 14, 2020, from https://www.crs.gov r43200 dabrowski, j. m., masekoameng, e., & ashton, p. j. (2009). analysis of virtual water flows associated with the trade of maize in the sadc region: importance of scale. hydrology and earth system sciences, 13, 1967-1977. https://doi.org/10.5194/hess-13-1967-2009 daugherty, k. (2019). u.s. agricultural trade data update. economic research service, 2(7). fader, m., gerten, d., thammer, m., heinke, j., lotze-campen, h., lucht, w., & cramer, w. (2011). internal and external green-blue agricultural water footprints of nations, and related water and land savings through trade. hydrology and earth system sciences, 15, 1641-1660. https://doi.org/10.5194/hess-15-1641-2011 https://doi.org/10.1016/j.agwat.2011.06.013 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 9 published by scholink inc. hoekstra, a. y. (2013). sustainable, efficient, and equitable water use: the three pillars under wise freshwater allocation. wires water. https://doi.org/10.1002/wat2.1000 hoekstra, a. y., & hung, p. q. (2004). globalisation of water resources: international virtual water flows in relation to crop trade. global environmental change, 15, 45-56. https://doi.org/10.1016/j.gloenvcha.2004.06.004 hoekstra, a. y., & hung, p. q. (2005). unesco-ihe, globalisation of water resources: international virtual water flows in relation to crop trade. global environmental change, 15, 45-56. https://doi.org/10.1016/j.gloenvcha.2004.06.004 hoekstra, a. y., & mekonnen, m. m. (2012). the water footprint of humanity. pnas, 109(9), 3232-3237. https://doi.org/10.1073/pnas.1109936109 hoekstra, a. y., chapagain, a. k., aldaya, m. m., & mekonnen, m. m. (2011). the water footprint assessment manual: setting the global standard. london: earthscan. islam, m. s., oki, t., kanae, s., hanasaki, n., agata, y., & yoshimura, k. (2007). a grid-based assessment of global water scarcity including virtual water trading. water resources management, 21, 19-33. https://doi.org/10.1007/s11269-006-9038-y kehl, j. r., & olshfski, e. (2015). gis mapping of water stress in kehl and mcguire, greening the desert. common ground and center for water policy, university of wisconsin-milwaukee. retrieved from https://ah2srmo3mb4 lopez-gunn, e., & llamas, m. r. (2008). re-thinking water scarcity: can science and technology solve the global water crisis? natural resources forum, 32, 228-238. https://doi.org/10.1111/j.1477-8947.2008.00200.x mekonnen, m. m., & ay hoekstra, a. y. (2011). national water footprint accounts: the green, blue and grey water footprint of production and consumption. value of water research report series, 50. mubako, s. t., & lant, c. l. (2013). agricultural virtual water trade and water footprint of u.s. states. annals of the association of american geographers, 103(2), 385-396. https://doi.org/10.1080/00045608.2013.756267 rost, s., gerten, d., bondeau, a., lucht, w., rohwer, j., & schaphoff, s. (2008). agricultural green and blue water consumption and its influence on the global water system. water resources research, 44, w09405. https://doi.org/10.1029/2007wr006331 tinker, r. (2019). drought summary, classification, and impact. climate prediction center, ncep/nws/noaa, college park, md, usa. u. s. geological survey (usgs). (2020). total water use in the united states, us department of the interior. retrieved march 2, 2020, from https://water.usgs.gov/edu/wateruse-total.html u.s. drought monitor (usdm). (2019). university of nebraska-lincoln. retrieved february 12, 2019, from https://droughtmonitor.unl.edu https://doi.org/10.1016/j.gloenvcha.2004.06.004 https://doi.org/10.1073/pnas.1109936109 https://ah2srmo3mb4/ https://doi.org/10.1111/j.1477-8947.2008.00200.x https://doi.org/10.1080/00045608.2013.756267 https://doi.org/10.1029/2007wr006331 https://droughtmonitor.unl.edu/ www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 10 published by scholink inc. u.s. geological survey (usgs). (2020). national water information system, us department of the interior. retrieved february 12, 2020, from https://waterdata.usgs.gov/nwis united states department of agriculture (usda). (2019). agriculture and food statistics: charting essentials. retrieved february 12, 2019, from https://www.ers.usda.gov/data-products/ united states department of agriculture (usda). (2019). agricultural baseline database. retrieved february 12, 2019, from https://www.ers.usda.gov/data-products/ https://www.ers.usda.gov/data-products/ https://www.ers.usda.gov/data-products/ energy and earth science vol. 6, no. 4, 2023 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 original paper contributions of aeromagnetic and field surveys to geological and structural mapping of pan-african province of south maradi, southern niger souley baraou idi 1* , moussa konaté 2 , abdoulwahid sani 1 & karimou dia hantchi 3 1 department of geology, university of agadez, agadez, niger 2 department of geology, abdou moumouni university, niamey, niger 3 department of geology, dan dicko dankoulodo university, maradi, niger * souley baraou idi, department of geology, university of agadez, agadez, niger received: october 22, 2023 accepted: october 30, 2023 online published: november 23, 2023 doi:10.22158/ees.v6n4p1 url: http://dx.doi.org/10.22158/ees.v6n4p1 abstract this study focused on geological and structural mapping of pan-african province of south maradi by using the aeromagnetic and filed surveys. the study zone corresponds to the northern part of the benin-nigerian shield, belonging to the pan-african mobile zone in the east of west african craton. previous geological work dates from the 1970s and limited to the summary geological map. according to this work, basement formations crop out discontinuously and are not subject by a structural study. in addition, the use of this map reveals a problem of correlation between the geological contours described on the existing map and those observed in the field. a combined analysis of aeromagnetic and field data led to complete then correct the petrographic and structural gap existing in the previous summary geological map since 1970s, which allowed to produce a new geological and structural map of studied zone (south maradi pan-african province). petrographic and structural analysis of this new map shows that the spatial distribution of geological formations is characterized by the alternating schist belts and mylonitic gneiss shear zones associated with migmatites panels and granitoïd intrusions. thus, the different petrographic facies mapped are represented by schists-micaschist, mylonitic gneiss, migmatitic gneiss and intrusive porphyric granites. previous data revealed a petrographic and structural continuity between south maradi pan-african formations with those of contiguous pan-african province of north nigeria. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 4, 2023 2 published by scholink inc. keywords aeromagnetic surveys, field work, geological mapping, schist belts, shear zones, pan-african province, south maradi, niger 1. introduction the south maradi basement represents the northern part of the benin-nigerian shield, belonging to the pan-african mobile zone in the east of west african craton (wac, fig. 1a). previous geological work was limited to the summary geological map of south maradi (fig. 1b, mignon, 1970). according to this map, the south maradi basement formations (magmatic and metamorphic rocks) outcrop discontinuously along the border with federal republic of nigeria. the basement formations disappear northwards under the hamadian continental sedimentary cover. in addition to this work, aeromagnetic mapping (prdsm, 2005) highlights the existence of major ductile deformation structures such as ductile shear zones. thus, two cartographic problems were identified between these pre-existing maps and field observations. the first one is that the ductile shear zones described by the aeromagnetic map (prdsm, 2005) were not represented on the summary geological map of mignon (1970). the second problem is related to the mismatch between the geological contours represented on the geological map (mignon, 1970) and those observed during the fieldwork. this study aims of to fill in these gaps and produce a new geological and structural map of the studied area. to achieve this objective, a methodological approach integrating aeromagnetic data interpretation combined with geological field surveys was implemented. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 4, 2023 3 published by scholink inc. figure 1. location of the study area within the simplified geological map of west africa (fig. 1a, after trompette (1973), modified). geological map of south maradi (fig. 1b, after mignon (1970)) note. legend figure 1a: 1: archean; 2: birimian; 3: pan-african mobile zones; 4: neoproterozoic to paleozoic sedimentary basins; 5: study area; 6: towns. legend figure 1b: γδ: granodiorites; gn: granitogneiss; l-gn: leptynites and fine banded gneiss; m: epi-metamorphic schists; g: cretaceous and continental terminal sandstones; qt: quartzite and sandstones; a: clay alluvium. 2. method the methodological approach integrates the interpretation of pre-existing cartographic data, particularly the geological map of south maradi (mignon, 1970) and the aeromagnetic map prdsm (2005), supplemented by geological field surveys carried out in the case of this study. 2.1 field work the field work consisted of geological cross-sections, petrographic descriptions and structural measurements of encountered formations. the geological cross-sections were surveyed perpendicularly to the major structures, which are oriented ne-sw or e-w (fig. 2). along each cross-section, the formations encountered were studied. this stage aimed to determine the different geological contours, www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 4, 2023 4 published by scholink inc. describe the identified petrofacies and measure their geological structures. the summary geological map of south maradi produced by mignon (1970) was used to plot the obtained petrographic and structural data obtained during the field work. 2.2 aeromagnetic survey well known for mapping sub-surface structures (grauch et al., 2006), the aeromagnetic map of the area (prdsm, 2005) are used to get a good correlation between geological structures and petrographic facies described during the field survey. therewith, the structural interpretation of the aeromagnetic map (prdsm, 2005) allowed a better interpretation of the tectonic structures (fig. 2b). the compilation of cartographic data (mignon, 1970) and (prdsm, 2005) and field data into the geographic information system (gis), wgs. 1984, enabled to modify and complete the summary geological map (mignon, 1970). the approach led to produce the new geological and structural map of this northern part of benin-nigerian shield. 3. result 3.1 structural interpretation of cartographic data this step included combining the geological map (fig. 2a, mignon, 1970) and the aeromagnetic map (prdsm, 2005), all of the studied zone. the geological map (fig. 2a) shows discontinuous basement outcrops unaffected by a preferential orientation structures. the structural continuity of geological formations, not identified on the summary geological map (fig. 2a), was deduced from the total aeromagnetic field map (fig. 2b). the extraction of magnetic lineaments from this map revealed the existence of major ductile shear zones forming a ne-sw trending beam. these shear zones are cutted by a posterior nw-se-trending fracture systems affecting the region (fig. 2b). the petrographic interpretation of aeromagnetic map of south maradi (fig. 2c, prdsm, 2005) has shown three major lithostratigraphic units: the garin wali gneissic and migmatitic complex (baggn et bamig), the maraka schist belt (mspmt) and the pan-african granitoïds (pagrn) represented by chirgué, nielwa-dan issa mylonitic gneiss, showing a relative petrographic continuity with summary geological map (fig. 2a, mignon, 1970). www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 4, 2023 5 published by scholink inc. figure 2. compilation of cartographic data note. (a) geological map (from mignon, 1970) showing the discontinuous basement formation, (b) aeromagnetic map (prdsm, 2005), showing a continuity of magnetic lineament in sub-surface, (c) pseudo-geological map from interpretation of magnetic map (prdsm, 2005). 3.2 petrographic and structural interpretation of field data the petrographic and structural analysis of four surveyed cross-sections (a-b, c-d, e-f and g-h, fig. 3) in the study area provided an idea on the deep distribution of the geological formations, as well as their geological structures (fig. 3). indeed, the distribution of geological formations shows a gradual transition from gneiss to migmatites (fig. 3). the schists form a ne-sw bands alternatively juxtaposed with gneissic shear zones trending in the same orientation (fig. 3). the correlation between the corresponding geological contours identified on the cross-sections, allowed to correct the poor outcrop quality highlighted on the summary geological (fig. 2a) and produce a new geological map of the study area (fig. 4). four schist belts, alternating with four gneissic shear zones, were mapped and named according to the different localities where outcrops are most important (fig. 4). from southwest to northeast, one can observe the maraka schist belt (msb), the goumata schist belt (gsb), the garin liman schist belt (glsb) and the mai dabaro schist belt (mpsb). the four gneissic shear zones cartographied are: the www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 4, 2023 6 published by scholink inc. fiawa-garin wali shear zone (fgsz), the goumata shear zone (gsz), the nielwa-dan issa shear zone (ndsz) and the garin liman shear zone (glsz) (fig. 4). these two lithofacies of metamorphic rocks are intruded by undeformed granitoïds. figure 3. different cross-sections surveyed from field work: cross-sections a-b of chirgué-goumata, c-d of garin-wali-maraka, e-f of the dan issa gari liman area and g-h of nielwa-maidaparo www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 4, 2023 7 published by scholink inc. 3.3 petro-structural study of mapped outcrops the different petrographic facies mapped during this study are: schist belt rocks, mylonitic gneiss, migmatitic gneiss and intrusive porphyry granites. 3.3.1 migmatite gneiss of south maradi in the south maradi basement, the migmatites gneiss outcrop in a several petro-facies including (fig. 4): paleosomes of porphyritic gneiss, neosomes of aplitic granites and melanosomes of biotitic restites. the presence of leucosomes and melanosomes indicates that metamorphism has reached higher degrees of amphibolite facies to granulite facies (ferré et al., 2002). in the garin liman migmatites, paleosomes are affected by anisopac folds with widely dispersed fold axes (fig. 5a), showing a transition to anatexis granites (neosome). this petrofacies is pink to gray color (fig. 5a). it consists of quartz, white centimetric crystals of feldspars and black beds of biotite, defining a disturbed foliation having several orientation varying from n30° to n50° (fig. 5a). the chirgué melanosomes (fig. 2) correspond to biotite enclaves in the porphyritic gneiss parleosomes (figs. 5b and 6). these enclaves correspond to assemblages of biotites, corresponding to a solid residue of partial melting (biotitic restites). the occurrence of large automorphous feldspar crystals in this solid residue (biotite melanosomes, fig. 6-b) reveals the porphyritic nature of the initial magmatic rock. figure 4. outcrop aspect of garin liman migmatitite gneiss (a) and chirgué migmatites (b) note. (a): paleosome affected by anisopac folds, with strong dispersion of fold axes in contact with an undeformed neosome. the paleosome-neosome contact is concordant. (b): porphyritic gneiss (diatextites) contain micaceous melanosomes of biotite. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 4, 2023 8 published by scholink inc. figure 5. enclaves of chirgué biotite enclaves in a ne-sw shear zone: s: foliation trajectory, c: shear plane 3.3.2 schist belt rocks in the south maradi, the rocks of the schist belt outcrop in the directions varying from n40° to n50° (fig. 7). these rocks are represented by sericite to chlorite schists and, rarely micaschists. these grey to green schists contain fined crystals of sericite and chlorite, quartz, k-feldspar as well as biotite and muscovite, defining a schistosity disturbed by synschistosity quartz veins (fig. 7b). some schist outcrops show the folded schistosity planes with vertical axial to subhorizontal axial plane of folds (fig. 7c-d). figure 6. outcrop aspects of the schists in the maraka schist belt note. (a and b): schistosity planes s1 n50°. (c): p1: subvertical to vertical axial plane. (d): p2: subhorizontal axial plane of folds. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 4, 2023 9 published by scholink inc. 3.3.3 shear zones rocks field observations show that in southern maradi, the mylonitic gneiss outcrop according to the discontinuous bands outcropping mostly in the streambeds. mylonitic gneiss were mostly observed in the garin wali-fiawa and dan issa-nielwa sectors (figs. 8 and 9). their outcrops form the n30° shear zones more than 5 km wide (figs. 3 and 4). these gneiss bands alternate with the “schist belts” that prolongate in the contiguous province of north nigerian (fig. 4). 3.3.3.1 mylonitic gneiss band of garin wali-fiawa the mylonitic gneiss of garin wali-fiawa outcrop in a band with a mean n25° direction (fig. 8). they are marked by the presence of centimetric porphyroblastic crystals of k-feldspars. the presence of these porphyroblasts reveals that the protolith is an alkaline granite (orthogneiss). the sigmoid shape of feldspars highlights an episode of ductile mylonitization, marked:  on the one hand, by the development of an s/c fabric (“σ-type structure”, passchier and trouw 2005). this s/c fabric structure reveals a senestre rotation component, which is particularly described in the pegmatitic gneiss (fig. 8a).  secondly, by a ductile boudinage of k-feldspars, associated with “δ-type structure” (passchier and trouw 2005, fig. 8b). the spiral shape of the winding indicates also a senestre shear component. figure 7. mylonitic gneiss from the garin wali and fiawa shear zone showing different types of deformation structures note. (a): k-feldspar porphyroblast gneiss with an s/c fabric senestre. (b): k-feldspar showing a “δ-type structure” senestre. c: n25° shear plane, s: foliation trajectory. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 4, 2023 10 published by scholink inc. 3.3.3.2 mylonitic gneiss band of nielwa-dan issa in this area, mylonitic gneiss outcrop in bands oriented mainly in n50° direction (fig. 9). macroscopically, the rocks are in gray-pink color, containing centimetric-porphyroclasts of k-feldspars and stretched crystals of quartz and biotite that define an s/c fabricated mylonitic foliation (fig. 9). figure 8. dan issa-nielwa mylonitic orthogneisses showing dextral shear microshiear zones. (b, d): respective interpretations of (a), (b) and (c). s: foliation trajectory, c: shear plane 3.3.4 porphyric granites these types of granite outcrop in the southwest of chirgué and rourouka villages (fig. 10), in the form of discontinuous plurimetric plutons. they also occur in the dan issa and kandamao areas. generally, these granites appear in the pink color and have a porphyritic texture revealed by automorphious crystals of k-feldspar, quartz and biotite (fig. 10). these granites are also known as “pink pophyric granite” of dan issa and kadamao villages. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 4, 2023 11 published by scholink inc. figure 9. porphyric granites outcrops of nielwa (a) and chirgué (b) 4. discussion the main structures and magnetic petro-facies described by aeromagnetic map (prdsm, 2005) and lithological units described by summary geological map (mignon, 1970) of southern maradi were correlated with the field data. this correlation shows that there is relative geological continuity between the summary geological map (mignon, 1970) and those deduced from aeromagnetic map (prdsm, 2005). in addition, the aeromagnetic map revealed the ductile deformation structures represented by ductile and brittle shear zones. the ductile deformation structures trending ne-sw and n-s, not described on summary geological map of south maradi (mignon, 1970) were confirmed by field observations and the aeromagnetic map (prdsm, 2005). geological contours and structures were also corrected by using of aeromagnetic map and field data. in addition, geological correlation with the contiguous northern nigeria province has shown a lithological, structural and geochronological continuity between these two pan-african provinces (mignon, 1970; prdsm, 2005; caby, 1989; talaat and mohammed, 2010; abubakar, 2012; baraou et al., 2018). according to ajibade and wright (1989), these lithostructural assemblages were formed during the same process of crustal block accretion, corresponding to the pan-african orogeny between 750-450 ma. 5. conclusion the combined analysis of aeromagnetic and field data led to correct petrographic and structural gap existing since 1970, and to produce a new geological and structural map of the south maradi pan-african province (pap). analysis of this new map shows that the spatial distribution of geological formations is characterized by the alternating schists and mylonitic gneiss bands associated with migmatites panels and granitoïd intrusions. thus, the different petrographic facies mapped are represented by schists-micaschist, mylonitic gneiss, migmatitic gneiss and intrusive porphyry granites. previous data revealed a petrographic and structural continuity between south maradi pan-african formations with those of contiguous north nigeria pan-african province. in the south maradi, the www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 4, 2023 12 published by scholink inc. greatest abundance of gold deposits is associated with the ne-sw and nw-se trending shear systems. thus, the petrographic facies mapped can be used as a proxy for the metamorphic origin of gold, associated with the late-orogenic events. acknowledgments special thanks to the staff of hanea (high authority for atomic energy of niger), particularly to mr abdou wahab djibo maiga for his technical assistance during the analysis and interpretation of aeromagnetic data. we thank also mr tidjani chetima, director of national center of mines and geological research (crgm, niger) for providing the summary geological map and technical assistance. references abubakar. y. i. 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(1994). early archaean component (>3.5 ga) within a 3.05 ga orthogneiss from northern nigeria; u-pb zircon evidence. earth and planetary science letters, 125(1-4), 89-103. https://doi.org/10.1016/0012-821x(94)90208-9 caby, r. (1989). precambrian terranes of benin-nigeria and northeast brazil and the late proterozoic south atlantic fit. geological society of america (special paper), 230, 145-158. https://doi.org/10.1130/spe230-p145 caen-vachette, m. (1986). contribution of isotopic geochronology for the knowledge of low paleozoic of west africa. publ. occas. cifeg., 10, 25-44. [origin language: french] ferré, e. c., gleizes, g., & caby, r. (2002). obliquely convergent tectonics and granite emplacement in the trans-saharan belt of eastern nigeria: a synthesis. precambrian research, 114-199, 219. https://doi.org/10.1016/s0301-9268(01)00226-1 https://doi.org/10.1016/0040-1951(89)90041-3 https://doi.org/10.1016/0012-821x(94)90208-9 https://doi.org/10.1130/spe230-p145 https://doi.org/10.1016/s0301-9268(01)00226-1 www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 4, 2023 13 published by scholink inc. grauch, v. j. s., sawyer, d. a., minor, s. a., hudson, m. r., & thompson, r. a. (2006). gravity and aeromagnetic studies of the santo domingo basin area, new mexico. in a. m. scott (ed.), u. s. geological survey. denver (pp. 63-86). kalsbeek, f., affaton, p., ekwueme, b., frei, r., & thrane, k. (2012). geochronology of granitoid and metasedimentary rocks from togo and benin, west africa: comparisons with ne brazil. precambrian research, (196-197), 218-233. https://doi.org/10.1016/j.precamres.2011.12.006 mignon, r. (1970). geological study and mining prospection in damagaram mounio and south maradi. ministry of mines and industry development of niger republic. technical report, 46-54. [origin language: french] passchier, c. w., & trouw, r. a. j. (2005). microtectonics (2nd, revised and enlarged edition). prdsm. (2005). geophysical mapping (aeromagnetometry, spectrometry and gravimetry) of south maradi basement. ministry of mines and industry development of niger republic. technical report, 9-10. [origin language: french] rahaman, m. a. (1976). progressive polyphase metamorphism in pelitic schists around aiyetoro, oyo state, nigeria. j. min. geol. nigeria, 13(2), 33-44. talaat, m. r., & mohammed, f. a. f. (2010). characterization of gold mineralization in garin hawal area, kebbi state, nw nigeria, using remote sensing. the egyptian journal of remote sensing and space sciences, 13, 153-163. https://doi.org/10.1016/j.ejrs.2009.08.001 trompette, r. (1973). le précambrien supérieur et le paléozoïque inférieur de l’adrar des mauritanie (bordure occidentale du bassin de taoudeni, afrique de l’ouest). un exemple de sédimentation de craton. etude stratigraphique et sédimentologique. trav. lab. sci. terre, marseille (st-jérome), 1-2, 573. https://doi.org/10.1016/j.precamres.2011.12.006 https://doi.org/10.1016/j.ejrs.2009.08.001 microsoft word ees-v2n1-p9.doc energy and earth science vol. 2, no. 1, 2019 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 9 original paper apply information system of maritime energy for improving performance in taiwan’s coast guard chi-tong lin1, c. w. chen1, c. y. j. chen3* 1national kaohsiung university of science and technology, taiwan 2 university of melbourne, melbourne, victoria, australia *corresponding author: c. y. j. chen, university of melbourne, melbourne, victoria, australia received: november 24, 2018 accepted: january 21, 2019 online published: february 13, 2019 doi:10.22158/ees.v2n1p9 url: http://dx.doi.org/10.22158/ees.v2n1p9 abstract taiwan is not a member of the international maritime organization country, and the domestic business is also a multi-horse carriage. there is no integration and a single government department is responsible. therefore, it is relatively difficult to check the relevant statistical inquiries, and the definition objects are also different. the information must be subject to the announcement of the international maritime organization. however, the data may be subject to statistical errors due to the construction of errors and omissions. the motivation of this paper is to roughly guess coast guard’s information system and maritime energy to discuss how to improve the work performance. materials use and cost estimates are resolved for both developmental and implementation activities. in addition, enhanced services costs are resolved to with total and average costs of standard eap services. these findings provide point of reference cost estimates for other eaps that may be considering offering enhanced services. keywords marine management, information technology, database system, employee assistance program 1. introduction taiwan is surrounded by the sea, and the sound development of ocean affairs is related to national rights and overall competitiveness. the sea guard office was formally established on january 28, 1989, and was adjusted to the ocean commission on april 28, 1975. it is an organ and has been renamed the marine commission sea guard (referred to as the sea guard), which is the coast and sea of the republic of china. the special agency for foreign security affairs is responsible for patrolling various ports, coastal areas, outlying islands, territorial seas, adjacent areas and it is an economic zone and carries out investigations on smuggling of goods and drugs, crimes and other public security matters. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 10 published by scholink inc. the geographic information system (gis) is a system designed to establish geographic information and space-related data, and to design and manage a spatial database. gis is a cross-disciplinary subject that combines geographic information and computer technology. it simplifies specific phenomena and events, and uses digital space and other technologies to capture, update, store, query, process, analyze, and display data through computer-efficient data. the function presents the characteristics of events in geospatial and provides real-world solutions to problems. the staff of the sea guard office is mainly composed of military, police and public servants, with a proportion of military personnel. most of them, since the implementation of the full recruitment system began on january 1, 107, the number of volunteers is higher than that of compulsory service. more, the maritime patrol agency pointed out that the statistics of the 102-106 annual recruitment of volunteers, soldiers, and soldiers are the rate of completion. 89.1%, 87.9%, 101.6%, 107.6% and 94.1%; 100%, 77.8%, 93.3% (not recruiting professional non-commissioned officers 103 years ago); soldiers are 56.3%, 87.3%, 107.7%, 93.5% and 117.7%. most of the military personnel are assigned to the grassroots units to the security checkpoints, and the executive services are mainly on duty. six items, such as watch, patrol, security check, check cabin and supervision and unloading, the work contents are as follows: a. perform duties such as communication, liaison, and communication of orders, notification, reporting, and handling of emergencies. b. watch the commanding heights or favorable monitoring position, the implementation of monitoring the surface of the sea, the port of the ship. c. patrol inspections and interceptions in the coastal areas to deter crimes. d. inspection of personnel, ships, vehicles and articles carried in and out of the trading port according to law check. e. check for any contraband or suspicious items in the cabin or other space above the ship. f. for the suspicious target ships, the monitoring of catch and unloading cargo shall be implemented. the duty is to take a 24-hour rotation. the average daily working time per person is about eight to twelve hours. the manpower of the inspection office is affected by the policy of military service reduction. at present, the manpower of the security inspection center is insufficient, which increases the workload of the sea patrol personnel. excessive stress, lack of sleep, etc., resulting in emotional instability, unable to adjust the working environment, and thus lead to the awareness of public security matters. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 11 published by scholink inc. 2. methodology-employee assistance program figure 1. geographic information system composition and spatial association the somali pirate attack has a high degree of regional clustering, and gis has been widely used in various fields. the spatial analysis of extension has been widely applied in various fields. in the future, according to the concept of time and space, the spatial distribution layer of somalia pirate attack points will be established, combined with electronic charts and natural factors (temperature, current, wave height, water depth, monsoon, visibility, wind direction, sunrise, sunset) database and objective factors (ship speed, warship patrol, international maritime sanctions, local muslim fasting month, ship security officer execution) to analyze the nature and hot trends of each sea area, in addition to understanding the case in addition to the spatial information such as characteristics and distribution, it can also be used by ship owners and masters and the international bureau to assist in the formulation of the somali piracy anti-theft security strategy decision and reference (icc international maritime bureau, 2011, 2012). equation 1 shows the cost components of providing standard eap services. because we are estimating the economic (opportunity) costs of providing standard services, the cost categories presented here should include the actual expenses paid by the eap plus the additional fair market value of any free or subsidized resources they received (french, dunlap, zarkinb, & georgia, 1998; bray, french, bowland, & dunlap, 1996; drummond, 1991). however, because the eap did not receive any free or subsidized resources for either standard oi enhanced services, we can rely solely on expenditure reports for our cost calculations. as shown, the total costs of providing standard eap services (c1) includes the value of labor (c2), contracted services (c3), materials (c4), equipment (c5), building space (c6) and miscellaneous resources (c7). www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 12 published by scholink inc. c1=c2+c3+c4+c5+c6+c7 (1) labor costs include the salaries and fringe benefits of all eap personnel. contracted service costs include the fees paid for any contracted labor or services that are used by the eap. building costs include rent, mortgages, or another measure of fair market value. employee assistance programs (eaps for short), is a new program developed in the corporate world since the 1970s. through internal management personnel or external professionals, it helps employees solve social, psychological, economic and health problems. an assistance program affects job performance. many countries are currently promoting this program, such as the netherlands, switzerland, etc... and many companies in taiwan are also assisting employees through this program, such as the police department, chunghwa post, taipei mrt corporation, and china national petroleum corporation. 3. results and discussions-coast guard’s law and regulations the eaps are not implemented by the southern division of the marine commission’s sea guards department. through the provision of service systems and the provision of professional services, the relevant factors and diversified services affecting individual performance are prevented or resolved. the service content is divided into working and living areas. the five aspects of health, organization and management are to cover the individual, organization and management level. by providing diversified and comprehensive assistance measures to improve the physical and mental health of the colleagues, the implementation contents are as follows (fleming, barry, manwell, johnson, & london, 1997; french, bradley, calingaert, dennis, & karuntzos, 1994; french, zarkin, & bray, 1995): 1) personal level: a. work surface: including work adaptation, organizational change adjustment, work and life balance, and career (retirement) planning. b. living surface: i. legal advice: including legal issues, car accidents, debts, inheritance, marriage, conflicts, etc. on official duties. ii. financial consultation: including tax treatment, debt processing, insurance planning, etc. c. healthy side: i. mental health: including stress adjustment, interpersonal relationship, emotional management, couple or parent-child communication, interpersonal communication in the workplace, and the response and management of major crises in all stages of life. ii. health care: provide medical and health care measures for current public officials of government agencies and relevant information on existing health care resources of civil society organizations. 2) the organization and management level: a. organizational aspects: including organizational change management, major stress event management, and performance improvement. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 13 published by scholink inc. b. management surface: including leadership control, interview skills, crisis management, team building, etc., and enable managers to assist in referrals when employees have problems affecting work efficiency. 4. conclusions and future study in addition to the fact that ships can suppress forced pirate attacks because of effective force, the general ship also reduces the fuel cost under high load because of the reduction rate approved by the maritime armed security personnel. in addition, many ship insurance companies also do not hire marine maritime security guards because the ship has to increase the additional risk premiums for ships, in accordance with the above-mentioned issues, the trend towards the use of maritime armed security guards should be the best way to assess the current piracy situation. if you explore the potential problems of your colleagues through the eaps service system, and discover, evaluate and solve problems, you can provide timely assistance according to the needs of the colleagues and the nature of the work, so that colleagues can work with peace of mind and look forward to creating an organizational culture that is willing to work and unite work to strengthen the competitiveness of the team. conflicts of interest the author(s) report(s) no conflict(s) of interest(s). the author along are responsible for content and writing of the paper. references bray, j. w., french, m. t., bowland, b. j., & dunlap, l. j. (1996). the cost of employee assistance programs (eaps): findings from seven case studies. employee assistance quarter, 78, 1-19. https://doi.org/10.1300/j022v11n04_01 drummond, m. (1991). reporting guidelines for economic studies. health econ, 4, 85-94. fleming, m. f., barry, k. l., manwell, l. b., johnson, k., & london, r. (1997). brief physician advice for problem alcohol drinkers: a randomized controlled trial in community-based primary care practices. journal of anwrican medkal association, 277, 1039-1045. https://doi.org/10.1001/jama.1997.03540370029032 french, m. t., bradley, c. j., calingaert, b., dennis. m. l., & karuntzos. g. t. (1994). cost analysis of training and employment services in methadone treatment. evaluation and program plattning, 17, 107-120. https://doi.org/10.1016/0149-7189(94)90048-5 french, m. t., dunlap, l. j., zarkinb, g. a., & georgia, t. (1998). the costs of an enhanced employee assistance program (eap) intervention. evaluation and programming planning, 21, 227-236. https://doi.org/10.1016/s0149-7189(98)00013-5 french, m. t., zarkin, g. a., & bray, j. w. (1995). a methodology for evaluating the costs and benefits www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 14 published by scholink inc. of employee assistance programs. journal of drug imes, 25, 45l-470. https://doi.org/10.1177/002204269502500213 icc international maritime bureau. (2011, 2012). piracy and armed robbery against ships annual report. energy and earth science vol. 5, no. 1, 2022 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 short paper the nigerian petroleum industry act, frontier basins exploration and the global energy transition nuhu george obaje 1* , abu kasim adamu 1 , abdullahi bomai 2 , mukhtar zanna 2 , james adeoye 1 , ishaq yusuf 1 , richard dauda 2 , faisal musa 2 , suleiman adamu 2 & lukman musa adamu 1,3 1 department of geology/department of biology/nigerian national petroleum corporation professorial chair in basinal studies, ibrahim badamasi babangida university, lapai, niger state, nigeria 2 frontier exploration services, nigerian national petroleum corporation, abuja, nigeria 3 department of earth sciences, kogi state university, anyigba, kogi state, nigeria * nuhu george obaje, department of geology/department of biology/nigerian national petroleum corporation professorial chair in basinal studies, ibrahim badamasi babangida university, lapai, niger state, nigeria received: march 10, 2022 accepted: march 21, 2022 online published: april 21, 2022 doi:10.22158/ees.v5n1p1 url: http://dx.doi.org/10.22158/ees.v5n1p1 abstract the nigerian petroleum industry act (pia) passed into law in 2021 has the major goal to reform the nigerian petroleum sector operations into policy, regulations and business (commercial). in the line of this, the nigerian national petroleum corporation (nnpc) was transformed to nnpc ltd to operate entirely commercially with a supervising board and registration with the corporate affairs commission. such a commercial mandate will entail the need to explore and produce more oil and gas for export and domestic utilization. oil is becoming less attractive as an energy source but gas is gaining momentum as a clean energy source in the global energy transition road-map. the global energy transition road-map is drawn around clean, alternative and renewable energies. the nigerian frontier basins have recently come on board as new business opportunities with huge petroleum gas resources. these frontier basins comprise the anambra, benue, bida, chad (nigerian sector), dahomey, and sokoto basins as well as the deep and ultra-deep offshore. maturing these basins through data generation and production of the gas resources therein will promote the nation’s gas utilization and gas expansion programmes meant to promote industrialization and huge employment generation, grow the economy and engender positive social transformation. the clause in the pia that promotes frontier exploration is well-thought out. available and required geological data needed to mature the frontier basins to producing basins are presented in this paper. the success made in kolmani river-2 well discovery is a case study. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 1, 2022 2 published by scholink inc. keywords nigeria pia, energy transition, frontier basins, alternative energy 1. introduction the recent passing into law of the nigerian petroleum industry act has a bearing on the ongoing exploration by the nigerian national petroleum corporation (nnpc) which in turn allows juxtaposition by the present global energy transition that demands deployment of renewable and alternative clean energies. economic growth in any society is anchored on the productive activities of the real sector whose performance is driven by energy availability. the level of economic development equally determines the human development indices such that in the african region, poor industrial performance resulting from gross energy deficit have resulted in stunted economic growth, high unemployment figures, and the resultant high poverty level, recurring political crises and youth restiveness. it is a recognized fact that availability and access to energy is a sine qua non for achieving industrialization in any country. asides from the huge impact of the energy sector on employment generation, it also acts as catalyst for sustainable development and enhances resource efficiency. indeed, energy is the “oxygen” of the global economy and the life-blood of growth in any nation. this paper has reviewed the relationship between the petroleum act, nigeria’s frontier basins and the global energy transition and the meaning to the country’s economic development in a sustainable physical environment. 2. methods of study this paper is generally a review of existing information and data, taken mainly from the nigerian petroleum industry act (2021) and the works of obaje et al. (2004) and obaje (2009). 3. results and discussion 3.1 the nigerian petroleum industry act the key attributes of the nigerian petroleum industry act passed into law in july 2021 embrace the creation of governance structures to ensure good governance and accountability, thereby ensuring a commercially oriented national petroleum company that fosters conducive business environments for petroleum operations. in the line of this, the nigerian upstream regulatory commission responsible for the technical and commercial regulation of the upstream petroleum operations; and the nigerian midstream and downstream petroleum regulatory authority responsible for the technical and commercial regulation of the midstream and downstream operations have been created. the commission and authority are exempted from the provisions of any enactment relating to the taxation of companies or trust funds. the nigerian national petroleum corporation (nnpc) has been incorporated as a commercial and profit focused nnpc limited with ownership vested in the ministry of finance incorporated (and ministry of petroleum incorporated) on behalf of the federation to take over assets, interests and liabilities of nnpc. this structure is expected to pave the way for eventually sale of shares www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 1, 2022 3 published by scholink inc. to nigerians. nnpc limited will earn 10% of proceeds of the sale of profit oil and profit gas as management fee while 30% will be remitted to frontier exploration fund for the development of frontier acreages in addition to 10% of rents on petroleum prospecting licences and mining leases. 3.2 frontier basins the clause enabling the nnpc limited to remit 30% profit to the frontier exploration fund attests to the desire of the nigerian government to harness the resource opportunities in the frontier basins. frontier basins are those sedimentary basins that are generally considered high-risk and under-explored and on which only scanty data are available. in nigeria, these basins comprise deep and ultra-deep offshore niger delta, and the intracratonic inland sedimentary basins embracing the anambra basin, benue trough, bida basin, chad basin, dahomey basin and sokoto basin. outside some portions in the anambra and dahomey basins where some acreages have been concessionaired to orient petroleum (anambra basin) and yinka folawiyo petroleum (dahomey basin), all of the remaining frontier basins are open acreages (figure 1). evaluation of potential petroleum systems and hydrocarbon proneness by previous workers indicate that nigerian frontier basins constitute a huge storage of natural gas and indeed with estimated 75% natural gas to 25% crude oil in volumetric ratio (obaje et al., 2004). the exploration success through the commercial discovery with kolmani river-2 well drilled by the nnpc is a classical attestation. figure 1. delineated blocks in nigeria’s sedimentary basins showing allocated acreages, acreages on offer and open acreages (courtesy of defunct dpr) www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 1, 2022 4 published by scholink inc. 3.3 global energy transition the energy transition is a pathway toward transformation of the global energy sector from fossil-based to zero-carbon by the second half of the present century. at its heart is the need to reduce energy-related co2 emissions to limit climate change. decarbonisation of the energy sector requires urgent action on a global scale, and while a global energy transition is underway, further action is needed to reduce carbon emissions and mitigate the effects of climate change. renewable (solar, wind, biomass) and alternative clean energy (natural gas) sources therefore constitute the fulcra for the global energy transition. data generated over the years show that nigerian frontier basins constitute huge storage of unproven natural gas and some oil. exploring and exploiting these natural gas resources align with the current global energy transition to cleaner energies of which natural gas is a big player therein. exploiting the natural gas resources will propel the drive towards a greener economy with the concomitant industrialization and employment generation. dismissed as a useless by-product of crude oil production until the second half of the 20th century, natural gas now accounts for 24 percent of the world's energy consumption (iea 2016). and the demand is growing. an environmentally-friendly and efficient energy source, natural gas is the cleanest-burning conventional fuel, producing lower levels of greenhouse gas emissions than heavier hydrocarbon fuels such as coal and oil. historically, natural gas also has been one of the most economical energy sources. natural gas fuels electric power generators, heats buildings and is used as a raw material in many consumer products, such as those made of traditional plastics. the international energy agency predicts that the demand for natural gas will grow by approximately 43 percent through 2035. figure 2. van krevelen diagram plot of hydrogen index against oxygen index values of frontier basins samples studies by obaje et al. (2004) and obaje (2009) showing that hydrocarbon resources in nigeria’s frontier basins are overwhelmingly gas www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 1, 2022 5 published by scholink inc. 4. conclusions the nigerian petroleum industry act (pia) (2021) is the law guiding and driving operations of the oil and gas industry in nigeria currently. it has the major goal to reform the nigerian petroleum sector operations into policy, regulations and business/commercial. to this extent, state-owned company, the nigerian national petroleum corporation (nnpc) has been transmuted into a limited liability company registered with the corporate affairs commission. it has to now operate strictly on commercial basis and to declare dividends to shareholders. such a commercial mandate will entail the need to explore and produce more oil and gas for export and domestic utilization. with global energy transition, oil is becoming less attractive as an energy source but gas is gaining momentum as a clean energy. the global energy transition is campaign for decarbonization and net-zero carbon focusing on clean, alternative and renewable energies. the nigerian frontier basins present business opportunities with huge petroleum gas resources. these frontier basins comprise the anambra, benue, bida, chad (nigerian sector), dahomey, and sokoto basins as well as the deep and ultra-deep offshore. maturing these basins through data generation and production of the gas resources therein will promote the nation's gas utilization and gas expansion programmes meant to promote industrialization and huge employment generation, grow the economy and engender positive social transformation. it is noteworthy that is already a clause in the pia that promotes frontier exploration. this paper has attempted to present available and required geological data needed to mature the frontier basins to producing basins. the nigerian national petroleum corporation has demonstrated this in the gongola basin exploration campaigns and the kolmani river-2 well commercial discovery. acknowledgements the nigerian national petroleum corporation is gratefully acknowledged for the endowment of the basinal studies professorial chair at the ibrahim badamasi babangida university, lapai, nigeria, and for the appointment of the first author as the first chair professor. references obaje, n. g. (2009). geology and mineral resources of nigeria (p. 240). springer verlag, heidelberg, berlin, new york. obaje, n. g., wehner, h., scheeder, g., abubakar, m. b., & jauro, a. (2004). hydrocarbon prospectivity of nigeria’s inland basins: from the viewpoint of organic geochemistry and organic petrology. aapg bulletin, 87, 325-353. the petroleum industry bill: top 20 changes you need to know. (2021). 7 july 2021. permalink. microsoft word ees-v2n2-p18.doc energy and earth science vol. 2, no. 2, 2019 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 18 renewable energy sources for the present and future: an alternative power supply for nigeria ebuete abinotami williams1, raimi morufu olalekan2 & ebuete ibim yarwamara3, oshatunberu modupe4 1 department of geography and environmental management, niger delta university, nigeria 2 department of community medicine, environmental health unit, faculty of clinical science, niger delta university, nigeria 3 department of art & social science, school of foundation studies, college of health technology otuogidi-ogbia town, bayelsa state, nigeria 4 department of environmental health, college of health sciences and technology, ijero-ekiti, ekiti state, nigeria received: june 22, 2019 accepted: august 5, 2019 online published: august 30, 2019 doi:10.22158/ees.v2n2p18 url: http://dx.doi.org/10.22158/ees.v2n2p18 abstract it is estimated that at least 600 million people in africa lack access to electricity and three out of five people don’t have access to electricity in sub-saharan africa. though africa is rich in a wide range of energy resources including solar, bio, natural gas, oil, coal and uranium, the continent is far from energy self-sufficiency. addressing climate change will require deep and quick reductions in fossil fuel use so that the systems developed around producing, transporting, and consuming energy are decarbonized by the middle of the century. in the ongoing age, sustainable power source has taken another swing to limelight on the planet, particularly in developed and emerging nations, as it assumes a noteworthy part both in economy and the general job of the world. significantly, nigeria an oil-rich country, comes as no surprise that almost all of her energy consumption comes from non-renewable energy sources as coal, natural gas and oil, and as such it is highly vulnerable to shocks due to overdependence on the fossil sources; often time is controlled by the international market. on the whole, the fossil fuel is expected to span only but a millennium (1700-2700) of human civilization while the imperative of an energy shortage situation is felt in every sector of the country considering the poor electricity consumptions in the country, which has reflected on the country’s economy and productivity rate. in revamping the economic sectors in nigeria, the need for an alternative energy sources that is augmentable in supply keeping in view sustainable development as the hallmark for all sector development. thus far, nigeria ought to likewise be opened to universal investments as this would help support the improvement of its assets. this paper, therefore, supports no other sources but renewable www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 19 published by scholink inc. energy in promoting the countries productivity at all segments. it further stressed on the implementation of the country’s renewable energy master plan (remp) to meet global competitors by the year 2030. similarly, senior political figures, policymakers and ceos should engage in a policy dialogue by identifying unique opportunities and best practices for developing and investing in nigeria and in africa’s energy markets for “…without this energy supply, the sophisticated skills of the industrial world are merely a burden in the struggle for survival.” keywords climate change, energy self-sufficiency, renewable energy, fossil fuel, power supply, energy markets, decarbonized, niger delta 1. introduction energy and public health among its various welfare effects is closely linked together at all scales and it use is central to human activity and can be viewed as the progressive development of new energy sources and their associated conversion technologies, from household and community to regional, national and global. energy and its systems have a central role in social, economic development and human welfare. though africa is rich in a wide range of energy resources including solar, bio, natural gas, oil, coal and uranium, the continent is far from energy self-sufficiency. as noted by the international energy agency (iea) at least 600 million people in africa lack access to electricity, and “three out of five people don’t have access to electricity in sub-saharan africa”. similarly, united nations development of economic and social affairs (un desa) also state that “…85% of the 1.2 billion people who lack access to electricity and 78% of the 2.8 billion who still rely on unsustainable solid biomass as fuel for cooking and heating, live in rural areas…” (un desa, 2014). this is unacceptable in economic and moral terms and no country should take it electricity and security issue as an excuse, with many african countries reluctant to liberalize their electricity sectors due to energy security concerns, private investment and security were not mutually exclusive (https://www.aa.com.tr/en/africa). thus far, the time is right to tap into alternative power supply potential which tends to play a key role in a clean, secure and affordable energy future. this can help tackle various critical energy challenges which offers ways to decarbonise a range of sectors including long-haul transport, chemicals, iron and steel where it is proving difficult to meaningfully reduce emissions. it can also help improve air quality and strengthen energy security. despite very ambitious international climate goals, global energy-related co2 emissions reached an all-time high in 2018. schematically, outdoor air pollution which knows no borders remains a pressing problem, with around 7 million people dying prematurely yearly; that’s 18,000 deaths daily. what’s worse, 92% of people around the globe don’t breathe clean air which is driven by fossil fuel usage that simultaneously drives climate change and contaminates our air. unfortunately, nine out of ten people breathe polluted air daily (who, 2016; www.who.int/news-room/details). in 2019, air pollution is considered by who as the greatest environmental risk to health and a major global health hazards with low and middle income countries www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 20 published by scholink inc. bearing the pollution brunt (raimi et al., 2018; olalekan et al., 2019). admittedly, most of the resources used like petroleum, natural gas, coal are not sustainable sources of energy. numbers of countries in the world including nigeria are currently passing through the critical phase of population explosion and the growing population demands more energy inputs. with this, the current population estimate range from 198 to 210 million people, growing at the rate of 3.2% per annum, nigeria faces the challenge of population impact on its poor infrastructural development (raimi et al., 2017; olalekan et al., 2018; raimi et al., 2018; raimi et al., 2019; olalekan et al., 2019; raimi et al., 2019). despite her rich natural resources, nigeria has a per capita income of around $390 and life expectancy of 45 years (world bank, 2006). a more graphic comparative data on the socio-economic condition of nigeria and electricity access in the year 2009: africa and other regional aggregates is presented in the table 1 and table 2 below: table 1. comparative data on socio-economic condition of nigeria and other developed countries indices (2006) nigeria malaysia uk usa population (millions) 201 25.2 59.4 293.5 gni per capita (atlas method, us$) 390 4,650 33,940 41,400 human development index (hdi) 158 61 15 10 poverty (head count ratio) 92.4 9.3 …. …. literacy (% of population age 15+) 67 89 95 95 gdp (us$ billions) 72.1 118.3 2,140.9 11,667.5 source: adapted from world bank, 2006 table 2. electricity access in the year 2009: africa and other regional aggregates country population without electricity (millions) electrification rate (%) urban electrification rate (%) rural electrification rate (%) africa 587 41.8 68.8 25.0 north africa 2 99.0 99.6 98.4 sub-saharan africa 585 30.5 59.9 14.2 developing asia 675 81.0 94.0 73.2 china & east asia 182 90.8 96.4 86.4 south asia 493 68.5 89.5 59.9 india 288 75.0 94.0 67.0 latin america 31 93.2 98.8 73.6 middle east 21 89.0 98.5 71.8 www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 21 published by scholink inc. developing countries 1,314 74.7 90.6 63.2 world* 1,317 80.5 93.7 68.0 * world includes oecd and eastern europe / eurasia. source: adapted from us energy information administration, world energy outlook 2011. total use of energy is related to population growth and economic output, but there is much variation in the effectiveness of energy use across societies (grubler et al., 2012). the amount of energy used, as well as the quality of energy, drives economic productivity; more efficient and flexible energy sources (liquid fuels and especially electricity) are associated with higher productivity (toman & jemelkova, 2003). currently, approximately 65% of all global primary energy is consumed in the industrialized countries that make up the organization for economic cooperation and development (oecd) and the former soviet union (fsu), with per capita consumption averaging five times that of developing countries (world bank, 2001). contributions to ghg emissions follow a similar pattern. per capita energy consumption in north america is more than 25 times that of the poorest nations in sub-saharan africa, 20 times the per capita consumption in india, and 10 times that in china (world bank, 2001). global carbon emissions are approximately one metric ton of carbon per year per person (tc/person-year). per capita emissions in the united states are more than 5 tc/year compared to approximately 0.6 tc/year in developing countries as a whole, and they are less than 0.2 tc/year in the 50 developing nations with lowest emissions (baer et al., 2000). coupled with low levels of per capita energy consumption, fuels and energy conversion technologies currently used in developing nations result in much higher exposure to local pollution. therefore, from an environmental health perspective, energy options in developing countries are of notable importance because of lack of access to clean energy sources and technologies. further, the most rapid future growth in energy consumption is expected to take place in developing countries, as a result of both population growth and economic development (reddy et al., 1996; reddy, 2000). however, nigeria suffers from poor infrastructural development including road networks which are still underdeveloped and there are a host of communities and cities cut off from each other due to unassailable transportation networks and electricity/power supply etc. the education system is under-funded and illiteracy rate is up to 40 percent. more than two-thirds of nigerians are poor. in 1980 an estimated 27 percent of nigerians lived in poverty. by 1990, 70 percent of the population had income of less than $1 a day and the figure has risen since then (needs, 2005). nigeria has one of the worst health care systems in the world and the doctor-patient ratio is about 1:1000. the public sector is very weak and on top of these, corruption threatens to crumble the country. as such, compared to the western standard, there is a total collapse of government in nigeria. the three major sectors of the economy are oil and gas, financial services and telecommunications. these sectors co-exist with thriving traditional agricultural and trading economies. this context of poverty, poor infrastructure and weak institutions provides a fertile ground for more vulnerability and to the ongoing impacts of climate www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 22 published by scholink inc. change (raimi et al., 2018; olalekan et al., 2019). interestingly, to have any chance of preventing runaway climate change and keeping human-caused temperature increases to no more than 1.5 degrees celsius (°c), societies must commit to rapid and deep decarbonization that will transform global and domestic energy systems. the threat of climate change demands a major energy transition (anita, 2015). however, a clear route from fossil fuels to clean energy has been slow to materialize (cameron & emma, 2017). a prominent yet contested route for facilitating a conversion to clean energy involves the use of so-called “bridging” fuels (christian, 2014), such as unconventional gas. as with other bridging fuels, their promotion and commodification rests on the argument that no single energy source can currently ensure accessible, reliable, and affordable energy, while also slowing the emissions lock-in of coal power (michael et al., 2016). nonetheless, unconventional gas provides a less carbon-intensive fuel source (relative to other fossil fuels), while still being abundant and feasible to access. schematically, the newfound popularity of unconventional gas has generated concerns regarding risks of high methane emissions, subsidence, changes in the use of food-producing land, water pollution, and reduced water availability (maria et al., 2014; morufu & clinton, 2017; raimi & sabinus, 2017; raimi et al., 2017; olalekan et al., 2018; olalekan et al., 2018; raimi et al., 2019; raimi et al., 2019). globally, the demand for energy remains on the increase and according to monique barbut, ceo and chairperson, global environment facility “between now and 2030, energy demand is projected to grow by 1.6% annually, adding up to a dramatic 45% increase. meanwhile, energy demand in developing and transition countries is predicted to grow even faster than in developed countries. such rapidly growing energy demand is particularly challenging given that most of the world’s population still rely on energy from limited fossil fuel sources and traditional biomass.” complete energy decarbonization would result in an unprecedented change to the world’s “social metabolism”, (manuel et al., 2015) altering not only the amount of fossil fuel based energy the world consumes, but also entire social and economic systems involved in resource extraction, processing, delivery and use (shelley, 2018). these systems include the human societies that have been built around providing the labour and capital necessary for fossil fuel exploitation, as well as the natural environments that have supported, and been degraded by fossil fuel extraction and combustion (gonzalez & toledo, 2017). the energy transformation necessary to mitigate climate change will profoundly alter societies and the natural world (clark et al., 2013). energy decarbonization has the potential to bring much more justice, opportunity, and sustainability to communities around the world. however, this will not happen without an intentional focus on the full social metabolism of the energy system. given the current fossil-fuel-dominated energy portfolio and projections for the development of renewable energy technologies, it is inevitable to conclude that fossil fuels will continue to supply an important percentage of the growing global energy needs during the next few decades. nevertheless, electricity generation, industrial processes, and transportation consume the most energy as well as contribute the most to greenhouse gas (ghg) emissions, in particular carbon dioxide (co2) (raimi et www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 23 published by scholink inc. al., 2018). interestingly, energy development is essential and a primary input for almost all economic activities and is therefore vital for improvement in quality of life. virtually, all human economic sectors utilised energy for its growth; such sectors includes industrial, commercial, transportation, telecommunications, wide range of agricultural and household services which has compelled us to focus our attention to ensure its continuous supply to meet our ever increasing demand (al-baijali & shamayleh, 2018) (figure 1). this global picture is not quite different when compared with the situation in europe where the major drivers of ghg are the energy and transport sectors with forestry having little or no contributions (figure 2). though deliberate efforts have been made by the government to provide power to all nigerians in order to spur development and improve livelihoods. the main sources for the country’s power production and hydropower, petroleum and natural gas. it is projected that the country’s energy requirements will substantially increase. the country’s energy policies must therefore ensure a robust and efficient energy system that is secure and sufficient. there are multiple energy sources, and the technical processes for harnessing, usage and impact on the environment vary from one energy type to another. the 2007 policy guidelines on energy takes cognisance of the need to protect the quality of the environment and the population from hazards of energy exploitation and utilisation. it further aims at improving the nations technical capacities in the energy sector for the state security, self-reliance and economic competitiveness, with increasing emphasis on renewable energy to facilitate green economic growth. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 24 published by scholink inc. figure 1. ghg emissions by sector, globally sources: data from climate change 2007; raimi et al., 2018 and greenhouse gas and emission trends and projections globally in europe (2007) www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 25 published by scholink inc. figure 2. ghg emissions by sector, and in the countries belonging to the european union sources: data from climate change 2007; raimi et al., 2018 and greenhouse gas and emission trends and projections globally in europe 2007 www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 26 published by scholink inc. according to dhameja (2013), energy demand is not an exception to the economic theory of limited means and unlimited want as in the place of exploitation. the energy resources have been growing overtime and has resulted in gradual depletion of the scarce reserves. the critical linked between energy and economy has exposed the vulnerability of nations to the volatile energy situation; which has reflected on the key factor in deciding the product cost at micro levels as well as indicating the inflation and the debt burden at the macro levels (ibid, 2013). in view of this, the nigerian government spent over $356billion on fuel subsidy in five (5) years (2010-2014) (bayagbon, 2018); and is currently spending ₦3.76 billion daily on fuel subsidy (chijioke, 2018) in managing fuel cost and inflation in nigeria. recently, the imperatives of an energy shortage (depleting energy crisis) situation confronting the world community has led to the formulation of a new energy policy framework of energy conservation within which the rate of growth and pattern of energy consumption could be regulated. this steady increase in gap has not only compelled technocrats and decision markers in the industry to develop new measures of energy conservation but also to have systematic approach towards present trend of energy consumption through energy auditing and application of modern techniques and methods for minimizing energy wastage. thus, relying solely on fossil fuels for the country energy supply will not be enough to meet the energy needs of the country. hence, the need for renewable energy sources considering the insurmountable factors confronting the energy supply in nigeria such factors according to oricha and olarinoye (2012) including government policies; economic factors, natural factors, society/community factors, efficient technology and security. nigeria is blessed with abundant of natural and human endowment, capable of transforming the nigerian power sector. the power sector who rely solely on fossil such as coal, oil, gas and water is vulnerable to shock because of the hovering change in crude oil price in the international market (newsom, 2012; shaabona & potinrinac, 2018). undoubtedly, the sector has witnessed a very insignificant amount of growth which has invariably affected its production capacity. inspit of the fundamental changes over the past few years in the nigerian electricity supply industry (nesi) under the government privatisation reform program in the global power industry even with the present 23 grid connected generating plants supplying power in the country; the total electricity consumption per capita in the country remain 1000kwhwhich compares poorly with 4,500kwh; 1,934 and 1,379kwh in south africa, brazil and china respectively (akuru & okoro, 2012; nwagbo, 2017). there is no gainsaying, the fact that a large percentage of nigerians (over 85million and more than 60%) do not have any form of accessibility to power and this in no small way affects their productivity and that of the country at large (nerc, 2008; oricha & olarinoye, 2012). paul (2017) stresses that, constant power supply is the hallmark of a developed economy and any nation whose energy need is epileptic in supply prolongs her development and risk-losing potential investors. in nigeria, there are few things that may discouraged investors as far as infrastructural development is concerned, which is nothing other than the amount of losses an investor would incur www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 27 published by scholink inc. since the electricity system in the country is outdated (ubari, 2013). most interestingly, is that nigeria has been ranked as the second worst nation in power supply by the year2017 as power dropped 3,851 megawatts from the 16,000gwh (www.vanguardngr.com/2018/01/nigeria), which is unequally distributed in the country. in view of the above, this paper address and redressed the importance of alternative renewable energy generation sources in the country’s power supply and utilisation to enhanced productivity in nigeria particularly in the niger delta region. the niger delta is a region located in the south-south geopolitical zones of nigeria, covering about 8% of the country’s landmass (wifa, 2018). the region is known as the storehouse of nigeria’s crude oil which accounts for approximately 90% of foreign exchange, paradoxically however, the region is yet in her own pervasive local poverty due to deep-rooted mistrust, frustrated expectation, unfavourable and erratic government policies, oil politics which is restlessly driven by powerful interests, the government and the oil firms, unprecedented restiveness etc, among leading factors is the power outraged, which has consistently drag on the region’s economic performance and expectation for development (raimi et al., 2019 in print). if all things been equal, the adoption of renewable sources of energy will reshape the economic productivity in the region, considering the vast opportunity for its adoptions. however, the current proposal for climate change mitigation is a portfolio of technologies that must be urgently and concurrently implemented. this portfolio includes renewables, energy storage, energy efficiency, bioenergy, nuclear energy, clean power generation, transportation, electrification and carbon capture, utilization, and storage (ccus), among others. however, it is important to understand that many of these technologies still require significant advances before they can be considered safe, reliable, and economically profitable. 2. energy policy/plan energy access for all is the single most important component of any development strategy. in the words of gerald foley— “…without this energy supply, the sophisticated skills of the industrial world are merely a burden in the struggle for survival.”(gerald, 1992). worldwide energy consumption and demand are growing up since past 50 years and according to monique barbut, “between now and 2030, energy demand is projected to grow by 1.6% annually, adding up to a dramatic 45%increase. meanwhile, energy demand in developing and transition countries is predicted to grow even faster than in developed countries. such rapidly growing energy demand is particularly challenging given that most of the world’s population still rely on energy from limited fossil fuel sources and traditional biomass.” the situation is worrisome leading nations to deregulate their power sectors to expand energy service to include renewable energies, attract private investment and attract independent power purchasers to the market. these appear to be essential for renewable energy development, even though privatization of the power sector is inherently biased against capital intensive investment in renewable energy. to create a favourable investment climate for private sector involvement in the delivery of clean and decentralized energy, a framework of laws, regulations and policies that is long term, www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 28 published by scholink inc. consistent, possess strong governance conditions, clear administration procedures, low transaction costs, strong public acceptance and enforcement is critical (xiadong, 2007). in effect, to sustain the expected fast pace of industrialization in the future, reliable and appreciable supply of renewable energies is needed. in addition, the national energy policy establishes guideline for the protection of the environment in the exploitation of nigeria’s fossil. it also emphasizes the exploration of renewable and alternative energy sources, primarily solar, wind and biomass. nigeria envisions a peaceful and prosperous nation driven increasingly by renewable energy. by the middle of the century, sustainable and affordable renewable energy will provide half of a country’s total energy demand, thereby contributing to the country’s effort to keep ghgs at barest minimum. the country’s renewable energy master plan (remp) has several pertinent specific objectives which if achieved will enable nigeria to address climate change risks in the energy sector, as well as ensure that the country meets it increasing energy demands. in particular the country will be able to pursue an economic development path that is less dependent on fossil fuels (e.g. oil). policy, according to thomas birkland, is about problem solving, and is shaped by social, institutional, political, and economic factors. public policy as applicable in this context, serves as a guide to decision making that would affect a greater variety of people and interests. this is why government and the policies made by government are sometimes so controversial, frustrating, and at the same time very important since the public is the source of political authority (birkland, 2014). these various policies on renewable energy in nigeria are faced with challenges of non-adoption, non-implementation, non-binding, erratic and inconsistency because it varies from one government to the other. where a government can easily discard existing policies to pave way for new ones, it becomes extremely difficult to attract investors whose investments are needed to bolster the sub-sector, which according to a 2011 report by the international centre for energy, environment and development (iceed), requires an estimate of about us $200billion to improve nigeria’s infrastructure for power, transport and water (ewah eleri et al., 2011). these policies must be transformed to provide concrete solutions to the energy crisis in nigeria. moreover, national policies and law play pivotal roles in the expansion of the renewable energy market as they have the capacity to either stimulate or stifle improved energy access. however, nigeria lacks an appropriate legislation that would address fairness and open access to the grid, robust feed-in-tariffs, simplified licensing process, renewable portfolio standards, capital reliefs, incentives, capacity building, standards and codes specification, research and development; these factors are important to drive the renewable energy market. a national legislation on renewable energy should align with articulated policy statements to create a favourable investment climate for private sector involvement in the delivery of clean and decentralized energy. nigeria needs a legally enforceable codified document that would promote energy services for both the urban population and the rurald wellers; policies alone, cannot deliver on this. it is believed that, law has the propensity of propelling the development of www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 29 published by scholink inc. renewable energy, which in turn can improve energy access and cause socio-economic development in the nation. 2.1 renewable energy over non-renewable energy economy of a nation refers to total wealth of that nation measured in gross domestic products (gdp) or gross national product (gnp). where there is an increase in gdp/gnp in a country, it is obvious that there will be imbalance in the demand and supply of energy as increase in gdp/gnp means more use of materials for production activities. dhameja (2013) opined that, the quest of meeting various human needs, man over-exploited the natural resources with total disregard to the incalculable harm being caused, leading to disastrous consequences, which has called for the post 1992 un conference on environment and development (unced) held in rio de janeiro, focused on the restrictions on the release of greenhouse gases, that can only be achieved through renewable sources of energy. renewable energy refers to energy (like solar, wind, geothermal, ocean tide, biomass) obtained from energy sources whose utilization do not result in the depletion of the earth’s resources. however, renewable energy is replaceable on a human time scale, having the inherent ability to reappear, or replenish themselves by recycling, reproduction or replacement, hence remained augmentable in flow. other energy sources are non-augmentable having some impact on the environment. fossil-fuel, coal, oil and natural gas do substantially more harm than renewable energy source by most measures including air and water pollution, damage to public health, wildlife and habitat loss, water use, land use and global warming emissions (raimi et al., 2018). in contrast, most renewable energy sources produce little to no global emission even when including “life cycle” emission of clean energy (i.e the emission from each stage of technology’s life-manufacturing, installation, operation and decommissioning). the ipcc (2011) opened that, the global warming emission associated with renewable energy are minimal. for instance, burning natural gas for electricity releases between 0.6-2 pounds of carbon dioxide, equivalent to per kilowatt-hour (co2e/kwh), coal emits between 1.4-3.6 pounds of co2e/kwh; while wind is responsible for only 0.02-0.04 pounds of co2e/kwh on a life-cycle basis, solar 0.07-0.2 co2e/kwh, geothermal 0.1-0.2co2 e/kwh, and hydroelectric 0.1-0.5 co2 e/kwh. increasing the supply of renewable energy would allow us to replace carbon intensive energy sources and significantly, nigeria global warming emissions. for example, a 2009 ucs analysis found that a 25 percent by 2025 national renewable electricity standard would lower power plant co2 emissions 277 million metric tons annually by 2025 (ucs, 2009). further, the air and water pollution emitted by coal and natural gas plants is linked with breathing problems, neurological damage, heart attacks, cancers, and premature death (raimi et al., 2018). the study of epstein et al. (2011) proved that an estimated life cycle costs and public health effects of coal and gas is 74.6 billion dollar every year. in nigeria the annual women death of 90,000 is linked to smoke inhaling form kitchen operation (nigeria current, 2014). renewable energy industry is more labour intensive, unlike fossil fuel industry that are typically mechanised and capital intensive, thereby creating more job opportunities. for instance, in 2016, the www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 30 published by scholink inc. wind energy industry directly employed over 260,000 full-time, equivalent employees in a variety of capacities (wiser & mark, 2017); while geothermal alone employed 5,800 (geothermal energy association, 2010); in contrast to the 160,000 employed by coal industry (dept. of energy, 2017). in 2017, the global employment from renewable energy was 500,000 according to channels tv (2018). again, renewable energy provides an affordable electricity prized if properly harnessed since the fuel is free. for instance, the channels tv (2018) put the prize ratio differences between non-renewable energy to renewable energy as 50%. in nigeria, single room pay monthly electricity bill fall between ₦3000-₦5000 irrespective of her epileptic nature, whereas solar power box supply by mtn cost 2000 only with constant power supply. this lag provides readily market for investors. in the u.s; over 500 factories invested into wind project, yielding about 13billion (wiser & mark, 2017); furthermore, renewable energy creates economic ripple effects, that is benefiting unrelated local businesses from increased household according to the epa (2010). renewable energy sources create readily income for individual and government in the form of property and income taxes. for instance, the nigerian government saves over 1.4 trillion naira from fuel subsidy removal annually (bayagbon, 2018); and if such gesture continues and possibly, the guest for renewable energy sources is achieved, then the country’s reserved will be robust. another advantage is that, the renewable energy industries are economical and multipurpose, because the same piece of land can be used for electricity generations as well as agricultural activities. furthermore, renewable energy are distributed including modular. distributive because it spans through large space of land with vase alternatives. modular because power generation is sequentially connected, hence a break off in one solar panel or wind fan will not obstructs power supply; thereby encouraging constant power supply. 2.2 sources of renewable energy renewable sources of energy offer several potential advantages. they do not irreversibly deplete finite resources, and most have a lower climate footprint than do fossil fuels. if managed well, they can pose minimal health risks and can yield social and economic benefits. whether the benefits are realized depends strongly on how renewable energy is produced. no energy source is free of health and environmental impacts. issues of land use, maintenance, materials inputs, and energy storage raise concerns about environmental, occupational, and community health impacts. 2.3 wind turbine wind energy is a manifestation of the solar energy and globally, wind power is one of the most expanded renewable and sustainable energy sources. wind has the potential to supply a significant portion of world energy needs and provides a small but growing segment of electrical energy, reaching 2% to 3% globally (with higher proportions in some countries, such as nearly 26% in denmark, 16% in spain and portugal, and 12%in ireland) (ren21, 2012). harnessing power from the wind is one of the cleanest and most sustainable ways to generate electricity as it produces no toxic pollution or global warming emissions. wind is also abundant, inexhaustible, and affordable in the niger delta which makes it a viable and large-scale alternative to fossil fuels. in 1980s, wind energy generation of the www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 31 published by scholink inc. world was 10 megawatts and in the year 2000 it was 14,000 megawatts (dhameja, 2013); and according to the financial time world renewable energy conference held in brussels, belgium, in 1999; and the green piece international estimates that if the trend continuous, wind power could supply 10% of the world’s electricity and create 1.7million new jobs by 2020 (christopherson, 2013). this effort would reduce global emissions of carbon dioxide (co2) by 10 billion metric tons. on a more perspective, every 10,000 megawatts of wind generated capacity reduces carbon dioxide emissions by 33 million metric tons if it replaces coal or 21million metric tons if it replaces mixed fuels. wind energy source is ideal particularly for mini-industries, rural areas, remote areas and forest houses. again, a wind energy mapping project conducted by the federal ministry of science and technology in 2002 to identify potential sites for exploitation which showed that wind energy could be harnessed in the northern border regions and some coastal states. as early as the mid-1960s, in the northern region of sokoto and garo, over 20 homes and a school used windmills to pump water but the following decades saw the prices of fossil fuel drop and therefore with cheap energy, wind power was not an appealing alternative; investments in windmill ceased as the infrastructure deteriorated. the reasons for this under development may lie in the lack of awareness, promotion and practical government support in form of subsidies or substantial facilitation for the import of the technology (mshelia, 2012). electricity generation from wind energy requires more investment even though, today, there is a 10mw wind farm at lambat, and rimi in katsina state (sambo, 2010). health benefits of wind power include the absence of greenhouse gas and other pollutant emissions during operation (although some emissions are associated with manufacturing the equipment), as well as the absence of aroutine waste stream. 2.4 solar power solar energy has the maximum potential of all sources of depleting fossil fuels as it has the maximum potential of all the sources of renewable energy (paul, 2017). three technologies are used to generate electricity from solar radiation: photovoltaic (pv) cells, which generate electricity directly; concentrating solar power thermal systems, which use a liquid to transfer absorbed heat to a steam generator that drives a turbine; and solar towers, which are effectively chimneys in which rising hot air powers turbine generators. solar energy echnologies have been deployed in both small-scale (mainly rooftop) applications and in large-scale electrical production. like wind, the sun provides a tremendous resource for generating clean and sustainable electricity. the current situation of renewable energy in nigeria shows that, there is an annual average of daily solar radiation of as high as 7kwh/m2/day in the coastal regions of nigeria. this means that the annual average of daily hours of sunshine varies from 9 hours in the north and up to 4 hours in the south. the total available solar radiation in nigeria could provide 120,000 times the total amount of electricity currently generated in the country. also, sunlight received during day hours and clear sky has power density of between 0.4kw/m2 and 1kw/m2. in nigeria, the current annual fossil fuel production in the country of 258.62million barrels and 4.11x1010 litres of crude oil amount to 4.2x105gwh of electricity production and out of the 5% technical www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 32 published by scholink inc. potential of solar energy in the country only 1.5x1018j is useful annually (oyedepo, 2012; nwagbo, 2017; premoboere & raimi, 2018), hence there is more to solar energy exploitation in the country. the major energy routes of solar energy utilization were; direct passive heating of building, farms, green houses, water; solar thermal electric power plants using steam cycle or binary cycle; solar photovoltaic power plants using several pv cells connected in series. the former is economically competitive in mini-industries, remote areas, satellite power supply, forest houses, mountain areas etc. for instance, the fee ratio between the nepa to solar is about 50% in nigeria (the channel, 2018). thus far, solar pv systems are gaining grounds in nigeria and can be found in sokoto, sokoto state; uyo in akwa-ibom state, solar pv for telecommunication along kaduna-abuja road and solar pv at ilaje, ondo state (world alliance for decentralised energy, 2009). the major health concern from solar power relates to the life cycle of pv cells. these are typically made with crystalline silicon and, depending on the technology used, include compounds such as copper indium diselenide (cis), copper indium gallium diselenide (cgs), gallium arsenide (gaas), and cadmiumtelluride (cdte). silica mining is associated with risk of silicosis, a type of pneumoconiosis (leung et al., 2012). pv manufacturing, like semi conductor manufacturing, may entail exposure to toxicmetals (cadmium, arsenic, chromium, and lead) and gases (arsine, phosphine, and silane) (fthenakis et al., 2008; taylor, 2010), available data suggest that environmental emissions are generally low (fthenakis et al., 2008), although waste management and end-of life product disposal remain challenges (silicon valley toxics coalit, 2009). overall the health impact of solar power is likely to be far less than that of any of the fossil fuels. 2.5 geothermal energy geothermal energy is the energy that lies embedded within the earth’s crust. there is increase in temperature of the earth with increasing depth below the surface; such heat is stored in the earth’s crust as thermal energy which constitutes an inexhaustible source of energy term as geothermal energy. the most widely developed type of geothermal power plant (known as hydrothermal plants) are located near geologic “hot spot” were hot molten rocks is close to the earth’s crust and produces hot water. according to khitoliya (2002), deposits of hot water and steam at relatively lesser depth (3000m) can be extracted from such deposits by means of production wells. the technology for its use is either through direct steam, flash or binary which required a cooling technology in the form of water-cooled or air-cooled. energy supply through geothermal is ideal for major and mini industrial activities, and domestic uses etc. furthermore, from the 2012 renewable energy master plan, (draft revised edition), there is no programme target nor a projected electricity supply from geothermal energy. does this mean nigeria has no plan for harnessing resources from geothermal energy? advocates of geothermal energy believe that nigeria is well endowed with the resource and should take advantage of it. according to timothy oladimeji “geothermal energy is a renewable resource, and production from individual geothermal reservoirs can be sustained for decades and perhaps for centuries.” he pointed out that “compared to other types of power plants, geothermal plants have relatively little effect onthe www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 33 published by scholink inc. environment, and geothermal power plants have been successfully operated in farms, in sensitive desert environments and in forested recreation areas.” geothermal energy in nigeria is yet to evolve; it should also be given adequate attention just like solar and hydro power energy (segun, 2013). 2.6 biomass for electricity this is energy sources from green plants. green plants capture solar energy through the process of photosynthesis and convert it into organic matter. this organic matter is known as biomass and is basically a form of solar energy, which is converted into chemical energy by the green plants i.e. solar energy in the form of chemical energy. bio energy is generated when this biomass is burned in the form of wood, charcoal and agricultural waste or animal. biomass power plants share some similarities with fossil fuel power plants; since both involved combustion of a feedstock to generate electricity. biomass plants raise similar but not identical concerned about air emissions and water use as fossil fuel plants. on the contrast, the feedstock of biomass plants can be sustainably produced, while fossil fuels are non-renewable. its production sources include energy crops (switchgrass), agricultural waste, manure, forest products and waste, and urban waste. the present contribution of biomass energy is between 4% and 18% of total primary energy consumption of various developed and emerging countries respectively. the situation is likely to be changed dramatically and rapidly during coming years with increase in the biomass energy consumption from 25% to 40% by 2015 (khitoliya, 2004). biogas has a high calorific value (5000 to 5500kcal/kg) which can be used for cooking processes, operating small engines when properly utilised can aid productions in nigeria. 2.7 hydro-energy hydrogen as a non-conventional energy resources has a tremendous potential as it can be produced from water which is available in abundance in nature. it has a very high energy content and its burning is non-polluting according to paul (2017). hydrogen can be produced from fossil fuels, but it is usually obtained from water by means of electrical energy which in turn may be generated from geothermal energy, wind energy, solar energy etc. the total hydroelectric power potential in nigeria is about 8,824mw and only 24% large scale and 4% small hydroelectric power potential have been exploited (oyedepo, 2012; nwagbo, 2017), hence more of the country’s hydro energy capacity remained unexploited. hydrogen energy can be used for generating electricity for operating domestic appliances and mini industry. some of the full advantage of this increasing momentum include. hydrogen is versatile. technologies already available today enable hydrogen to produce, store, move and use energy in different ways. a wide variety of fuels are able to produce hydrogen, including renewables, nuclear, natural gas, coal and oil. it can be transported as a gas by pipelines or in liquid form by ships, much like liquefied natural gas (lng). it can betransformed into electricity and methane to power homes and feed industry, and into fuels for cars, trucks, ships and planes. hydrogen can enable renewables to provide an even greater contribution. it has the potential to help with variable output from renewables, like solar photovoltaics (pv) and wind, whose availability is not www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 34 published by scholink inc. always well matched with demand. hydrogen is one of the leading options for storing energy from renewables and looks promising to be a lowest-costoption for storing electricity over days, weeks or even months. hydrogen and hydrogen-based fuels can transport energy from renewables over long distances from regions with abundant solar and wind resources, such as nigeria, australia or latin america, to energy hungry cities thousands of kilometres away. hydrogen can be used much more widely. today, hydrogen is used mostly in oil refining and for the production of fertilisers. for it to make a significant contribution to clean energy transitions, it also needs to be adopted in sectors where it is almost completely absent at the moment, such as transport, buildings and power generation. there have been false starts for hydrogen in the past; this time could be different. the recent successes of solar pv, wind, batteries and electric vehicles have shown that policy and technology innovation have the power to build global clean energy industries. with a global energy sector in flux, the versatility of hydrogen is attracting stronger interest from a diverse group of governments and companies. support is coming from governments that both import and export energy as well as renewable electricity suppliers, industrial gas producers, electricity and gas utilities, automakers, oil and gas companies, major engineering firms, and cities. investments in hydrogen can help foster new technological and industrial development in economies around the world, creating skilled green jobs particularly for the growing youth population in nigeria. 2.8 hydro-kinetic energy this deals with the energy sources from waves and tidal/power which encompasses an array of energy technologies; many of which are in the early stages of development. the difference in the level of ocean water between high tide and low tide results in the ocean tide energy which is renewable. tidal energy is a form of hydro energy occurring with every tide. the rise and fall of tidal water are maximum near seashore and river mouths (bays), so the choice of hydro-energy situations in the niger delta region of nigeria is economically. the estimated tidal power in the world is about 3000x109 mw. out of this about 1000x109mw is of shallow tides (<2m) and is not favourable for conversion and only about 2000x109 is likely to be usefully extracted. hydro-kinetic energy is ideal for industrial and domestic uses. 3. effective support feats of renewable energy in nigeria including niger delta researchers have established that renewable energy is available in nigeria (newsom, 2012; shaabona & potinrinac, 2014; nwagbo, 2017). the effectiveness of renewable energy includes the following: availability of waves for potential hydro-kinetic energy productions and the abundant of wind is an added advantage in the niger delta considering her geographical location in supporting hydro-kinetic and wind farm. the intensity of the sun is very high and its durations in most part of the year could spine through ten (10) hours of the day (november-april and august) in the niger delta, hence supporting solar farm for electricity supply in the niger delta. again, the niger delta region is located www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 35 published by scholink inc. within the tropical rainforest readily supporting the regular supply of feedstock for the biomass industry (eli, 2012). similarly, revolutionary strategies to increase national sustainable energy production by alternative power supply including biomass waste management and reusing it in systematic form may help to reduce dependability of nigeria on other fossil fuel consumption. alternative power supply technology is also a good option of sustainable energy and can be easily implemented in a country like nigeria (figure 3). figure 3. strategy for possible government stress reduction sources: adapted from gauri et al., 2013 4. barriers to the development of renewable energy in nigeria the introduction of renewable energy in generating electricity or providing energy is not new to emerging countries including nigeria. with the abundance of renewable energy resources, energy crisis should not be experienced, however, this is not the case. the following are barriers to the development of renewable energy in nigeria: lack of an institutional framework: the energy commission of nigeria (ecn), nigeria atomic energy commission (naec), nigerian nuclear regulatory agency (nnra), nigerian electricity regulatory commission (nerc), nuclear power plant operating organisation (npp-oo) and national emergency management agency (nema), nigerian environmental standard regulatory commission (nesrea) etc provide for responsibilities by different agencies in carrying out activities for the development of renewable energy technologies. this is a problem because co-ordination www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 36 published by scholink inc. especially in the exchange of information between government ministries, parastatals and agencies is erratic, uncoordinated, weak and rather complex. the proper harmonisation and synergy of a specific agency robs the sector of a driving force for its growth and development. it is therefore important that an agency is given the mandate to propel the sector. lack of public awareness: the awareness of the opportunities offered by renewable energies and its related technologies is low among private and public sectors. this lack of information creates a market gap that results in what renewable energy is perceived to be. it is believed that, renewable energy technologies are not yet mature for the nigerian environment, it is expensive and suited only for the wealthy few. these and many more perceptions need to be corrected and the gap filled with the dissemination of information on renewable energy resources, availability, benefits, opportunities and potentials. awareness in this respect is paramount to building public confidence and acceptance of these technologies. non-implementation of existing policies: the problems or challenges the agencies face are multi-sectoral. they range from government policies down to community or societal apprehensive of public utilities. government policies are erratic, lack implementation and uncoordinated. in turn, these result in apparent lack of very reliable database. also, the several policies on renewable energy are most often not implemented due to lack of political will. a certain degree of policy short sightedness characterizes the implementation of policies of the country as very few concreteactions are taken to build the groundwork for meeting future energy security, as well as economic, social and environmental challenges (energy commission of nigeria and united nation development programme, 2005). research and development shortfalls: research and development activities are vital to sustainable socio-economic advancement of any nation. presently in nigeria, there are six (6) renewable energy centres having the responsibilities of research into various aspects of renewable energy but they are under-performing (energy commission of nigeria, 2014). it is important that these centres are given adequate attention with regards to key issues such as energy development and utilization. this can be done by initiating and promoting energy related research and development programmes and these programmes must be result oriented and market driven (organisation of african states, 2015). lack of manpower development and training: there is inadequacy in capacity building in the energy sector of the nation’s economy. compared to the population of the country, there are insufficient energy related courses in most tertiary institutions (energy commission of nigeria, 2014). capacity building is lacking in the following areas viz: training of manpower to install, operate and maintain renewable energy technologies; development of manufacturing capabilities; development of critical mass of scientists, engineers, and economists to design an effective and functional institutional framework. it has become necessary to develop the human capacity needed to meet the manpower requirement of the renewable energy sector of the nation (efurumibe, 2013). the lack of a legal framework: there is no law but policies governing renewable energy in nigeria. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 37 published by scholink inc. to achieve adequate energy supply where renewable energies play a major role, the creation of an appropriate legal framework is necessary. the lack of a law on renewable energy could affect contractual obligations, property rights, transfer of technology, and fair competitive bidding processes for potential domestic and international investments. a law can ensure certainty and compliance, giving investors a degree of confidence in the government. 5. conclusion energy is imperative for any nation’s development and improvement thus for nigeria to develop they require a relentless increment in the measure of energy they create yearly. however, nigeria needs to investigate its sustainable power source assets and make great utilization of it in order to upgrade monetary development and furthermore increment in the future of its natives and occupants. as fossil fuel age is expected to span only 1000 years of human civilization (1700-2700)according to khitoliya (2004); considering the ever-increasing population and fuel consumption rates, and increase in petroleum product prices; the energy starvation is been felt by every developed and less developed country; renewable energy sources remain an alternative energy sources. switching to renewable energy resources in nigeria will not only led to positive contributions to rural development, lower health cost, energy independence and climate change mitigation, but will increase the energy capacity and availability in nigeria; thus, bridging the energy gaps in the rural areas. worthy of note is that, renewable energy sources (wind, solar heat, waves, etc) cannot be stored in original natural form, rather converted continuously to electrical form, transmitted, distributed and utilized without long-term intermediate storage, making it available in large quantity and free of cost. hence, consumption of renewable should be maximised to enhance productivity in the country and save future generation from inherited negative actions laid down by the predecessors. the wide vision behind vitality arrangement must be to meet energy requests dependably with energy which is spotless and moderate, and this must be done in an earth practical way utilizing diverse energizes and types of vitality, regular and non-customary, and in addition new and rising sources to guarantee supplies constantly. it is basic for nigeria to have a steady energy approach, together with persistent quest for energy proficiency and protection, amplifying coal generation and enhancing the rail and port framework and in addition improvement of elective foundation for coal transportation, for example, waterfront waterways on the grounds that coal, being the least expensive type of vitality, will be the banner carrier of nigeria’s vitality needs. policymakers should therefore undertake a comprehensive approach to energy decarbonization that aims to rapidly replace fossil fuels with zero-carbon energy resources while improving the economic and social welfare of communities around the globe. thus far, governments, senior political figures, policymakers, businesses, ceos, development partners i.e. non-governmental organizations (olalekan et al., 2019; raimi et al., 2019), and others will need to engage in a policy dialogue identifying opportunities and best practices for developing and investing in africa’s energy markets and develop smart and adaptive strategies to ensure a socially just, yet rapid, www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 38 published by scholink inc. energy transition for innovation and investment to rectify the lack of energy in the region. to date, however, most policies focused on energy decarbonization which have failed to take a system-based approach (james et al., 2014). although there are now several studies and analyses that demonstrate how energy systems could achieve rapid decarbonization (mark et al., 2015) very few governments have developed comprehensive strategies to change their energy systems (miller & jones, 2018). as a roadmap for the future, key recommendations to help governments, companies and others to seize this chance to enable clean energy to fulfill its long-term potential include. a) implement the national policy on renewable energy and support research &development (r&d) to bring down costs. alongside cost reductions from economies of scale, r&d is crucial to lower costs and improve performance. b) there should be successful implementation of the country’s renewable energy master plan (remp) of 2006. this will explore renewable energy in quantities and at prices to promote equitable sustainable growth in the country. by installing enough wind, solar pv, solar thermal and hydroelectricity nationwide. c) engage internationally and track progress. enhanced international co-operation is needed across the board but especially on standards, sharing of good practices and cross border infrastructure. hydrogen production and other alternative power supply use need to be monitored and reported on a regular basis to keep track of progress towards long-term goals. d) develop and implement energy efficiency programmes in different sectors of the economy, as well as public and private buildings and eliminate unnecessary regulatory barriers and harmonise standards. e) there should be enabling environment, economically attractive to encourage ready market for renewable energy by re-investing the annual fuel subsidy of 1.4trillion naira gained from the country’s fuel subsidy removal to boost renewable energy sector. f) promote adaptation of the cleaner production concept in all energy production and consumption activities. g) focus on four key opportunities to further increase momentum over the next decade. by building on current policies, infrastructure and skills, these mutually supportive opportunities can help to scale up infrastructure development, enhance investor confidence and lower costs:  make the most of existing industrial ports to turn them into hubs for lower-cost, lower-carbon hydrogen and other alternative power supply.  use existing gas infrastructure to spur new clean hydrogen supplies and other alternative power supply.  support transport fleets, freight and corridors to make fuel-cell vehicles more competitive.  establish the first shipping routes to kick-start the international hydrogen trade and other alternative power 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(2007). legal and policy frameworks for renewable energy to mitigate climate change. issue 2 winter. climate law reporter 7: article 7. retrieved august 11, 2015, from https://digitalcommons.wcl.american.edu www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 2, 2019 44 published by scholink inc. wifa, b. m. (2018). developing a model legal and justice in the niger delta region: prospect and challenges afflicting the niger delta region. focus nigeria, 8(2). http:// www.focusnigeria.com williams j. h. et al. (2014). pathways to deep carbonization in the united states. retrieved december 3rd, 2018, from http://unsdsn.org/wp-content/uploads/2014/09/us-deep-decarbonization-report.pdf wiser, r., & mark, b. (2017). 2016 wind technologies market report. u.s department of energy, usa. https://doi.org/10.2172/1375677 world alliance for decentralised energy (wade). (2009). august. the potential of decentralised energy in nigeria. world bank. 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(2001). world resources 2000-2001: people and ecosystems: the fraying web of life. new york: oxford univ. press. energy and earth science vol. 6, no. 2, 2023 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 30 original paper geophysical mapping by electromagnetic induction of gold occurrences in birimian formations of liptako: case of sorbon haoussa sector (souhwest niger) abdoulwahid sani 1 & souley baraou idi 1* 1 department of geology, university of agadez, agadez, niger * souley baraou idi, department of geology, university of agadez, agadez, niger received: may 5, 2023 accepted: may 17, 2023 online published: june 5, 2023 doi:10.22158/ees.v6n2p30 url: http://dx.doi.org/10.22158/ees.v6n2p30 abstract the survey zone corresponds to the sirba greenstone belt, one of liptako birimian formations (lbf) of niger. previous aeromagnetic and geochemical works reveal the significant gold occurrences. the present study integrates geophysical mapping of these occurrences by electromagnetic induction on field. a multi-frequencies system of 10 frequencies was used for depth and subsurface investigation of resistive anomalies. the interpretation of obtained results shown two types of resistive anomalies, corresponding to the conductive units: deep anomalies obtained with low frequencies and subsurface anomalies detected with high frequencies. the subsurface anomalies were detected around the 15 meters and the deep anomalies were recorded beyond 80 meters. all of the detected resistive anomalies are in a lenticulars shapes oriented n-s or e-w. the analysis of combined resistivity map from all frequencies shown three zones of resistive anomaly presenting a high potential in conductive metals: the first zone z1 (most important), located in eastern studied zone covering, covering a surface of 3.5 km 2 , the second zone z2 is located in west and covers an area of 2.9 km 2 and the third anomaly zone z3 is located in south with a surface of 0.96 km 2 . on field, these conductive units correspond to auriferous quartz veins and/or highly altered manganese schists, exploited by using the artisanal mining wells, up to 20 meters in depth. keywords electromagnetic induction, resistive anomaly zone, gold occurrences, sirba greenstone belt, liptako birimian formations, niger www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 31 published by scholink inc. 1. introduction the studied area (sorbon haoussa) is located in northeastern part of the sirba volcano-sedimentary belt, one of the three belts of lower proterozoic birimian greenstone formations to the sw of niger (figure 1a). the two main geological units are the granitic batholite to the se and the volcano-sedimentary formations to the nw. the survey area covered a surface of 21 km 2 with the altitudes varying from 220 to 264 meters (figures. 1b, c). this zone is well known for its significant gold mineralization, generally contained in graphitic and or manganous schists (project ner/88/023, 1991; jica, 1993; colin brown, 1998; project padem, 1995; claude jobin et al., 2010). it has significant gold occurrences (jica, 1993; padem project, 1995; claude jobin et al., 2010), which are exploited by using artisanal mining pits, systematically implemented. previous works are limited to airbone geophysic (project ner/88/023, 1991) and geochemical (jica, 1993; project padem, 1995; sems exploration services ltd. 2009; claude jobin et al., 2010) prospection. this study aims to determine the subsurface and depth spatial distribution of these occurrences. to achieve this objective, geophysical method by multi-frequency electromagnetic induction was adopted. these surveys specifically allowed the mapping of conductive (mineralized zones) and resistive (host rocks) units as well as the directions, thicknesses and depths of the anomalies. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 32 published by scholink inc. figure 1. locations of the study area within the geological map of liptako birimian formations of niger (a, b) (machens, 1973; dupuis et al., 1991; abdou et al., 1998) (c): topographic map and e-w electromagnetic survey grid www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 33 published by scholink inc. 2. method multi-frequency electromagnetic surveys allow to detect and map mainly the variations of conductive units in the subsurface (acdi, 1973; grauch et al., 2006) conductive veins and fractures. the survey grid used in the case of this study is consisted of 21 parallel lines with e-w direction (figure 1c). the measurement stations are equidistant of 50 meters and are marked by stakes set up and surveyed with differential global positioning system (dgps). the promis-10 system used in this work is a new multi-frequency electromagnetic induction technology that can send up to 10 frequencies up to 14 080 hz, 28160 hz and 56320 hz for high frequencies. the other frequencies are 110 hz, 220 hz, 440 hz, 880 hz (low frequencies) and 1760 hz, 3520 hz, 7040 hz (medium frequencies). in this system low frequencies are the most penetrative while high frequencies allow the investigation of the sub surface. in addition, the promis-10 can record secondary magnetic fields along three axes x, y and z. the measurements are made profile by profile. at each measuring station, the system passes automatically from one frequency to another, which makes it possible to carry out a vertical survey (in depth). the subsoil is thus characterized horizontally and vertically along each profile, which allows to map the conductive anomaly in depth and in subsurface. geo-electric parameters such as resistivity, depth and thickness of each conductive level are also determined. the depth of investigation varies according to the transmission frequency, the resistivity of medium and transmitter-receiver distance. in general, it is equal to half of the transmitter-receiver distance but can reach 100 to 125% of this distance depending on the conductivity of the medium. the principle (from the general viewpoint) is described as follows: when an electromagnetic wave penetrates the underground, it induces eddy currents in any conductive body (faraday’s law of induction) which then generates a disturbing magnetic field (ampere’s law) of the primary magnetic field of the transmitter. the primary field hp and the secondary field hs are recorded at the receiver (figure 2). www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 34 published by scholink inc. figure 2. electromagnetic induction device with transmitting (transmitter tx) and receiving (receiver rx) loops showing the process of penetration of electromagnetic field into the underground and the generation of electric currents and recorded secondary magnetic fields 3. result 3.1 results of electromagnetic survey the results of the electromagnetic survey are distributed as follows (appendix 1): total number 21 profiles carried out oriented east-west, spaced of 200 meters. total length of the profiles: 101.000 m and 2037 drilling points spaced of 50 meters. the data obtained allowed on the one hand to determine the geo-electrical parameters, in particular the resistivity, the thickness and depth of the anomaly (appendix 2) and on the other hand to map the resistive anomaly zones (low, medium and high frequencies) corresponding to the conducting levels. 3.2 analysis and interpretation of resistive anomaly 3.1.1 anomaly maps for low frequencies the resistivity anomaly maps, low frequencies (110 hz, 220 hz, 440 hz; d), 880 hz; figure 3 shows a spatial variation in the electrical resistivity data. they highlight the existence of an e-w conductive structure located on profile 12. this structure is highlighted by the 110 and 220 hz frequencies (figure 3 a, b) which are the most penetrative. a resistivity anomaly appears also in the eastern part of survey zone, marked by very low resistivity values revealing the high conductive units with varying depths. the presence of shallower resistive units that can be un-mineralized quartz veins (resistivity between 300 and 500 ohm.m) can be observed. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 35 published by scholink inc. the resistivity anomaly map, from all low frequencies (figure 4) shows that the high conductivity units have a lenticular shape (green, blue and red color) contained in a resistive unit (host rock). these conductive lenses show a n-s alignment in the east of the zone, which can be considered as a zone having a highly potential in conductive metals (gold anomaly). the scattered high resistive lenses are observed in the center and in south of the zone, forming a cluster oriented e-w (figure 4). on field, the conductive lenses correspond to quartz veins and/or highly altered manganese schists, operated by using the mining wells up to 20 meters in depth (figure 5). figure 3. resistivity anomaly maps for low frequencies: a) 110 hz), b) 220 hz, c) 440 hz; d), d) 880 hz www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 36 published by scholink inc. figure 4. combined resistivity anomaly map for all low frequencies, showing the spread high conductive units in lenticular shapes (green, blue and red color). other colors represent resistivity units (host rocks) figure 5. photographs of host rock outcrops for gold showings and artisanal mining pits, showing the gold bearing outcrops www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 37 published by scholink inc. 3.1.2 anomaly maps for medium frequencies medium frequencies are less penetrative than low ones. analysis of the resistivity anomaly maps for the mid-frequencies (figure 6) confirms the existence of three anomalous zones oriented n-s highlighted by the low frequencies (figure 6 a). in addition, the 3520 hz and 7040 hz frequency maps (figure 6 b and c) show the highly resistive levels, oriented n-s that can correspond to mineralized quartz veins. figure 6. resistive anomaly maps for medium frequencies: a) 1760 hz), b) 3520 hz, c) 7040 hz 3.1.3 anomaly maps for high frequencies the high frequencies are the least penetrative and their depth of investigation varies from 1 to 10 meters for subsurface conductive units. the 14080 and 28060 hz high frequency maps (figure 7a, b) show the presence of subsurface conductive units in east, west and south. whereas the 56320 hz frequency map (figure 7c), more superficial, shows resistive levels in south specifically on the first 6 profiles, in extreme north and west. these resistive levels could be the acidic intrusive units (granodiorite/granite) and un-mineralized quartz veins (claude jobin et al., 2010). the abundance of resistive units in 56320 hz frequency map (figure 7c) reveals the high meteoric alteration of host rocks on the surface. in the field, the conductive units (gold mineralization) are either associated with alluvium from meteoric alteration of manganese schists, or generally associated with highly altered quartz veins with low sulphide content. they are identified in the artisanal mining pits of gold. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 38 published by scholink inc. the resistivity map from all frequencies (figure 8) shows the spatial distribution of high mineral potential anomalies in the study area. three resistivity anomaly zones with a high potential in conductive metals can be referenced z1, z2 and z3 (figure 8): the first zone z1 (most important), located in east of the area has a n-s trend and covers an area about 3.5 km2; the second zone z2 is located in west with a n-s direction and covers an area of 2.9 km2; the third anomaly zone z3 is located in south with a surface of 0.96 km2, oriented n-s. figure 7. resistive anomaly maps for high frequencies: a) 14080 hz, b) 28060 hz, and c) 56320 hz. rc: resistivity contour www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 39 published by scholink inc. figure 8. spatial distribution map of high potential zones in conductive minerals from all frequencies showing the location of drill points and associated anomaly depths 3.3 analysis of geo-electric data geo-electrical parameters (resistivity values, anomaly depth and thickness) of anomaly by profile are indicated in the appendix 2. four types of anomaly according to resistivity values are observed: very high (1 to 7 ohm.m), high (7 to 10 ohm.m), medium (10 to 19 ohm.m) and low (19 to 52 ohm.m). the projection of anomaly depth (figure 8) show that the high values of depth are concentrated in east corresponding to z1 of the survey zone and relative low values of depth in northwest corresponding to z2 and in south z3. these observations reveal that the anomaly zone z1, located in upstream (figure 1c), corresponds to the deep anomaly (primary) and z2 and z3 subsurface anomalies (secondary). the secondary anomalies zone z2 and z3, located in downstream can be interpreted as result of upstream (z1) high alteration. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 40 published by scholink inc. 4. discussion petrographically, the survey area consists of altered black schists crossed by dolerite, quartz and granite dykes (claude jobin et al., 2010). the observation on field shown that the conductive lenses highlighted by the resistivity anomaly map (figure 4) correspond to auriferous quartz veins and/or highly altered manganese schists, operated by using the mining wells up to 20 meters in depth (figure 5). petrographic observations carried out in the artisanal mining wells shown that the black schist formations and acidic intrusive units are the main host rocks of conductive lenses. the geochemical prospection carried out in these host rocks revealed the gold contents varying from 20 ppb to 300 ppb (jica, 1993). according to claude jobin et al. (2010), these black schist formations represent a chemical trap favorable to the gold precipitation from mineralized fluids. according to the same authors, a structural control of gold mineralization is associated to the features oriented n60° (m’banga, tiringui cluster), n90° to n110° (sefa nangue), n130° to n140° (samira, libiri, koma bangou), n350° to n10° (tera and allareni clusters), all located in southwest of survey area. further in southwest of studied zone, magnetic and aeromagnetic data from several auriferous sites of burkina-faso have showed the similar observations. indeed, in these regions, gold mineralization is tectonically controlled by an irregular ne-sw (n60° to n90°) shear zone and hosted by small geophysical anomalies units corresponding to an altered and silicified green schist facies (sawadogo et al., 2018; aziz et al., 2016; bilardello & jackson, 2014). 5. conclusion this study focused on the geophysical mapping of gold occurrences in sirba greenstone belt, specifically in the sorbon haoussa area. using multi-electromagnetic induction methods allowed to obtain thematic maps of deep and subsurface resistive anomalies. geo-electric parameters such as resistivity, depth and thickness of conductive level are also determined. the projection of anomaly depth on resistivity map (all frequencies) led to determine the zone of high potential in conductive metals. this study helps to understand the geometry of anomalous zones as well as the depth and thickness of anomalous units. it constitutes also a guide to improve mining operations, which are hitherto artisanal. acknowledgments the authors are grateful to the om goldstone staff for their scientific collaboration and technical support, especially for electromagnetic data to carry out this work. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 41 published by scholink inc. references abdou, a., bonnot, h., bory, k. d., chalamet, d., saint, m. m., & younfa, i. (1998). explanatory note of geological maps of liptako at 1/200 000. ministry of mines and geology. niger republic. ministère des mines et de la géologie, rep. niger. [origin language: french] acdi. (1973). report on aeromgnetic survey of liptako gourma. ministry of mines and energy. niger republic. [origin language: french] aziz, o., ousmane, b., gbélé, o., eric, g., & saga, s. (2016). caractérisations structurales des gîtes aurifères du corridor de bouboulou-bouda au burkina faso, afrique de l’ouest. afrique science, 12(5), 89-104. [origin language: french] bilardello, d., & jackson, m. (2014). a comparative study of magnetic anisotropy measurement techniques in relation to rock-magnetic properties. tectonophysics, 629, 39-54. https://doi.org/10.1016/j.tecto.2014.01.026 claude, j. p., & souleymane, c. (2010). report on drilling tialkam deba permits sirba belt, liptako, niger part 2. dupuis, d., pons, j., & prost, a. e. (1991). emplacement of granitoids plutons and characterization of birimian deformations of western niger. comptes rendus de l’académie des sciences, paris, 312, 769-776. [origin language: french] grauch, v. j. s., sawyer, d. a., minor, s. a., hudson, m. r., & thompson, r. a. (2006). gravity and aeromagnetic studies of the santo domingo basin area, new mexico. in a. m. scott (ed.), u. s. geological survey, denver (pp. 63-86). jica. (1993). mining prospection report in sirba region (vol. 20). niger républic. [origin language: french] machens, e. (1973). contribution to the study of basement formations and sedimentary cover in western niger republic: mémo. brgm (no. 82, p. 167). [origin language: french] project ner/88/023. (1991). aeromagnetic and electromagnetic surveys in liptako region. geophysical general campany. [origin language: french] project padem. (1995). research of gold occurrences in liptako region. in final report klöckner (p. 162). ministry of mines and energy. republic of niger. [origin language: french] sâga, s., séta, n., hermann, i., abraham, s. t., samuel, n., & martin, l. (2018). the belahourou granite pluton (djibo greenstone belt, burkina faso): emplacement mechanism and implication for gold mineralization along a shear zone. journal of african earth sciences. sems exploration services ltd. (2009). interim report covering gold exploration proposals on the sirba project. sw niger. https://doi.org/10.1016/j.tecto.2014.01.026 www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 42 published by scholink inc. appendixes appendix 1. results of electromagnetic surveys profile number of measurements by profile profile length (m) profile 1 56 2800 profile 2 65 4200 profile 3 75 3700 profile 4 80 4000 profile 5 86 4300 profile 6 90 4500 profile 7 97 4800 profile 8 102 5050 profile 9 107 5300 profile 10 113 5600 profile 11 115 5700 profile12 116 5750 profile 13 113 5600 profile 14 116 5750 profile 15 113 5600 profile 16 109 5400 profile 17 104 5150 profile 18 104 5150 profile 19 96 4750 profile 20 92 4550 profile 21 88 4350 total 2 037 101 000 www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 43 published by scholink inc. appendix 2. geo-electrical parameters of anomalies by profile profile (p) anomal stations ohm.m thickness (meters) depth (m) depth corrected (m) rms (%) anomaly p2 s1 7.22 10.58 19 36 6.04 high s2 8.77 6.02 9.55 23.46 5.64 high s3 22.39 20.00 21.23 33.03 3.62 low s4 5.01 3.62 12.84 16.80 7.35 very high s5 14.40 10.60 13.51 15.45 2.65 medium p3 s1 9.04 11.16 19.99 40.37 2.31 high s2 2.47 5.16 18.05 41.67 4.95 very high s3 6.04 7.58 22.08 51.22 2.29 very high s4 6.53 13.77 23.62 53.85 2.62 very high p4 s1 15.04 17.30 36.37 69.45 4.93 medium s2 15.61 16.73 35.79 67.12 4.81 medium s3 5.22 11.74 18.23 45.49 6.00 very high p5 s1 2.48 5.56 15.59 21.98 3.569 very high s2 3.35 8.74 17.88 27.46 4.127 very high s3 6.62 19.11 26.26 36.75 2.3819 very high s4 2.27 6.00 15.01 25.69 3.3145 very high p6 s1 19.41 17.81 23.49 26.38 7.14 medium s2 18.44 16.88 17.63 19.73 4.91 medium s3 40.92 25.90 87.16 111.27 1.69 low s4 2.52 5.01 20.01 49.59 8.79 very high s5 3.62 7.67 19.16 51.62 2.35 very high s6 6.35 10.71 21.04 53.07 4.44 very high p7 s1 19.64 32.56 38.54 73.88 1.57 low s2 5.13 11.34 22.66 56.98 8.33 very high s3 5.55 11.88 22.79 55.70 8.07 very high p8 s2 7.39 12.02 30.94 74.03 3.53 high s3 21.36 52.09 64.01 80.76 4.94 low p9 s1 3.34 7.96 18.32 59.11 2.48 very high s2 5.68 13.86 25.30 65.94 8.21 very high s3 6.99 25.86 34.05 56.25 10.10 very high s4 2.05 6.91 16.22 16.22 36.47 very high s5 19.16 24.78 49.03 68.16 3.07 low www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 44 published by scholink inc. s6 13.00 23.14 33.50 49.01 8.59 medium s7 16.63 16.03 27.79 31.81 2.96 medium p10 s1 8.81 17.27 38.14 52.81 8.64 high s2 6.11 34.85 37.78 57.74 12.85 very high s3 2.35 7.20 16.95 39.24 3.30 very high p11 s1 52.02 18.79 89.90 89.86 3.37 low s2 6.98 7.62 46.41 59.54 3.80 very high s3 7.16 12.04 17.46 21.11 3.16 high s4 22.82 11.61 13.05 16.33 3.29 low p12 s1 5.48 10.20 12.77 13.66 11.99 very high s2 10.58 17.32 27.00 27.86 5.31 medium s3 2.06 0.92 0.92 3.34 2.96 very high s4 10.84 7.18 7.75 13.02 2.94 medium s5 19.56 14.98 25.22 28.85 10.38 low s6 6.40 18.79 44.50 48.39 8.47 very high s7 13.95 14.55 27.34 54.27 7.39 medium s8 13.61 20.79 22.37 45.56 6.69 medium s9 38.88 25.79 37.97 60.63 8.39 low p13 s1 9.44 14.33 22.23 31.65 9.53 high s2 21.39 22.15 22.15 45.45 1.49 low s3 23.85 22.08 22.08 41.48 6.55 low s4 6.05 26.07 26.72 45.61 13.76 very high s5 27.63 1.55 28.27 47.16 13.76 low s6 12.47 0.16 0.16 20.45 12.02 high s7 6.82 33.11 33.26 53.55 12.02 very high p15 s1 11.96 15.75 19.04 20.45 3.36 medium s2 15.36 31.37 31.37 33.54 9.50 medium s3 14.30 26.01 27.89 30.31 6.21 medium s4 7.05 16.27 25.87 28.69 7.48 high s5 10.76 18.26 25.32 31.49 10.52 high s6 3.26 2.07 3.23 17.21 6.74 very high s7 7.41 21.51 29.06 44.64 6.69 high s8 6.87 2.44 3.99 22.99 6.58 very high s9 9.32 23.31 27.30 46.30 6.58 high p16 s1 20.43 29.43 37.24 42.81 9.96 low s2 16.83 23.76 27.94 37.85 23.71 medium www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 45 published by scholink inc. s3 11.85 22.84 23.70 35.12 9.06 high s4 4.27 22.34 23.87 38.43 12.53 very high s5 3.49 13.46 14.06 31.60 7.32 very high p17 s1 8.25 10.65 11.07 26.38 3.09 high s2 1.43 0.81 1.52 12.67 7.22 very high p18 s1 6.75 15.08 15.66 21.44 2.19 very high s2 6.84 24.48 27.12 36.72 11.55 very high s3 6.97 0.25 0.25 10.64 13.47 very high s4 3.18 17.69 21.72 33.22 7.57 very high s5 5.23 19.95 22.25 36.99 4.32 very high p19 s1 4.58 15.45 18.55 34.70 5.79 very high s2 4.08 9.97 19.20 32.85 5.07 very high s3 4.35 13.33 15.17 27.36 2.98 very high s4 4.58 15.45 18.55 29.85 5.79 very high microsoft word ees-v2n1-p1.doc energy and earth science vol. 2, no. 1, 2019 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 original paper overview in big data analysis of the japanese defense system: ambiguous adjustment to a strategic environment change chih-wei chen1, c. w. chen1, c. y. j. chen2 1 national kaohsiung university of science and technology, taiwan 2 university of melbourne, melbourne, victoria, australia * c. y. j. chen, e-mail: johnnychen@unimelb.edu.au received: november 22, 2018 accepted: december 1, 2018 online published: january 30, 2019 doi:10.22158/ees.v2n1p1 url: http://dx.doi.org/10.22158/ees.v2n1p1 abstract taiwan and japan are both maritime countries. the natural resources in the territory are quite limited. due to this inherent limitation, both taiwan and japan rely on trade to safeguard their own economic interests. therefore, defending the maritime traffic lines and ensuring maritime interests are important missions of the taiwan and japan defense systems. the recent increasingly harsh international situation in the asia-pacific region has seriously affected the security and stability of the surrounding areas. invisible also poses many challenges to taiwan’s maritime rights and interests, so it is a reflection on taiwan’s future development by understanding the japanese defense system. keyword japan’s defense ministry, national security assurance strategy, defense plan, medium-term defense force preparation plan 1. introduction security developing demands in every single filed beyond domestic economic and environmental protection (read & fernandes, 2003; lewis et al., 1978). in the security environment around japan, various problems and unstable factors have become prominent and sharp, and such situations are becoming more and more serious. among them, the factors in the asia-pacific region will have a far-reaching impact on japan’s national interests. it includes the modernization of neighboring countries and the strengthening of military power, and similar trends and military activities are becoming more and more prominent. under the development of lack of transparency and rapid expansion of sea power, the ccp military forces are rapidly changing the military balance in the asia-pacific region. at the same time, according www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 2 published by scholink inc. to the sovereignty of the east china sea and the south china sea, which are inconsistent with the international order, it is extremely difficult to change the regional status quo. can lead to misunderstanding and increase the risk of emergencies (john, 1967). the south china sea is an important node connecting the pacific ocean with the indian ocean to the straits of malacca. shipping accounts for about one-third of the world’s trade each year. an important maritime traffic line that is stable and economically prosperous in the international community. especially for japan, which relies on trade, the region is more known as the sea in japan. in addition, china has made large-scale rapid reclamation in the south china sea and strengthened various constructions for military purposes, by changing the status quo and increasing tension. the situation is to stabilize the situation in which a country enjoys regional rights, which has a serious negative impact not only on the economy but also on the security of the asia-pacific region (martin, 1972; randall, 1994). the aggressive actions on the diaoyu islands have not stopped. at the beginning of august 2016, dozens of “chinese marine police boats” began with an unprecedented frequency. invade the waters around the taitung islands. it is surrounded by hundreds of militia fishing boats. this can be said to be a large-scale upgrade of the traditional offensive. 2. methodology-japan’s security environment north korea has repeatedly conducted nuclear tests and ballistic missile tests under international sanctions, and has developed military forces on a large scale with a strong belief in the use of force, and has continuously maintained and strengthened asymmetric military capabilities, including the development and deployment of nuclear and ballistic missiles. weapons of mass destruction and the maintenance of large special forces. this is not only a serious threat to japan’s regional and international security. on the other hand, north korea’s kidnapping of japanese nationals has always been a serious problem of japan’s sovereignty and people’s life safety, and it is one of the responsibilities of the country. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 3 published by scholink inc. figure 1. japan’s sea traffic line (east asia strategic overview, 2018) 2.1 gray events surrounding economic rights japan’s gray situation between territorial, sovereignty and maritime rights is gradually becoming longer-term, and these usual gray events may become a more serious risk of hidden national security. among them, the dispute between the ccp and the southwestern islands of japan and the east china sea is the most serious. in addition to the ccp’s official duties, the ship intermittently invaded the japanese territory around the southwestern islands, and a small unmanned aircraft invaded the airspace. in addition, russia in the north, even in the case of a more substantial reduction in the country’s overall budgetary expenditures, still gives priority to ensuring defense spending, while in the far east. in addition to conducting large-scale exercises, the russian army also deployed ground-to-ship missiles in the russian northern territories and coastal areas, and is scheduled to be in the thousand islands. 2.2 non-traditional security threats in addition to frequent natural disasters in japan, japan is located in coastal areas with nuclear power plants, and infrastructure such as industry, population, and network communications are concentrated in metropolitan areas, and invisible security concerns arising from the great east japan earthquake have been buried. if disasters such as major earthquakes occur again, it is still possible that extremely serious damage will occur, affecting not only japan but also the international community. therefore, japan urgently needs to take comprehensive measures to deal with large-scale natural disasters that may occur in the future. 3. results and discussions-japan’s strategy 3.1 national security strategy in a security environment in view of the above-mentioned security environment, what is japan’s national security strategy in response to these threats? four priority objectives are keys, such as economic recovery, educational www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 4 published by scholink inc. revival, diplomatic and security revival, and life rejuvenation. these four goals are related to each other and to each other influences. however, the scope of this study is only for the following aspects of japan’s foreign and security aspects. the abe government has promoted the foreign policy of values of the arc of freedom and prosperity. government officials and other government officials have actively visited countries around the world, including asean. with the changes in the strategic environment in the asia-pacific region, peace and prosperity in the region, through economic partnerships and communication networks, to achieve freedom, democracy, basic human rights, the rule of law and prosperity values. among them, strengthening the japan-us alliance, through strengthening the close us-japan alliance, its influence has become safe for japan and the region. important outside. in addition, under the premise of the deterrence provided by the united states, japan will expand its security role and mission, not only for itself. security defenses are also designed to ensure regional and global territorial security. to this end, japan is responsible for the responsibility of the alliance under the accompanying economic growth. the role of the role and play the role of the role is born. to this end, under the premise of article 9 of the japanese constitution and the security of the united states and japan, the traditional weapons attack and the “grey state of affairs” that are neither wartime nor normal, the japanese strategy and policy have been playing a more active role. figure 2. security assurance strategy organization structure www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 5 published by scholink inc. figure 3. relationship between national security strategy, defense outline, and medium-term defense 3.2 national defense strategy under the national security strategy the national defense strategy is based on the national security strategy. from the perspective of active pacifism, it strengthens its diplomatic strength, defense and other capabilities, and strives to expand its role in the region and internationally. in addition, on the basis of the japan-us alliance, it will work closely with foreign policy. the us-japan security treaty is the foundation of japan’s security guarantees. the us-japan alliance centered on the us-japan security system can stabilize security in the asia-pacific region. in addition, according to the india-pacific strategy in the asia-pacific region, the united states is strengthening its cooperation with japan and other allies by maintaining and strengthening its presence in the region, promoting security and stability in the region, and expanding and deepening cooperation with countries. in addition, japan is striving to establish a comprehensive defense system and an organizational structure that integrates mobile defense to strengthen prevention and response to various situations and to protect territorial, territorial and airspace security. according to the japanese constitution, japan implements the basic policy of defending itself, and it will never become a military power that constitutes a threat to other countries, and it must abide by the three principles of literati leadership and non-nuclear. in response to the threat of nuclear weapons, the nuclear suppression provided by the united states is absolutely indispensable, and the ballistic missile defense is achieved through japan’s own defense forces to ensure the safety of national life and property. 3.3 national military strategy under the national defense strategy in accordance with the guidance of the japanese military strategy, when military conflicts are likely to occur, it is extremely important to grasp the signs of war in advance. the troops must complete the deployment and concentration before the enemy launches the attack, and integrate the army, sea and air forces to obtain local advantages and attack the invading enemy. however, from the source of the conflict, if the military forces have a certain deterrent, the enemy will not dare to open the war easily. therefore, judging from japan’s current defense system, in the face of increasingly severe peripheral threats, the existing japanese defense force is not enough to deter the enemy from creating conflicts. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 6 published by scholink inc. therefore, it is urgent to provide nuclear suppression and conventional force through the united states to strengthen from peacetime to the deterrent and response capabilities of all stages of an emergency are also a very important part of the us-japan security treaty in the japanese defense system. in the ballistic missile defense section, japan’s current ballistic missile defense system is equipped with the sm-3 block ia air defense missile as the high-altitude interception of the ballistic missile cruise phase, and the patriot pac-3 air defense missile system is responsible for the ballistic missile. return to the final stage of the atmosphere, and the automatic warning and control system (jadge) integrates ballistic missile protection to effectively implement multi-layer defense. in order to reduce the burden of the aegis ship, the future defense province will build a land-based aegis system to strengthen the ballistic missile protection. figure 4. bmd preparation and application concept www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 7 published by scholink inc. figure 5. warning of the surrounding sea area 4. conclusions and future study during the second world war, the japanese army launched the pearl harbor attack on december 8, 1941, which caused an unprecedented blow to the us navy. despite the temporary victory, but ultimately ended in defeat, and after being restricted by the allies after the war, the japanese constitution clearly has no other military forces capable of launching armed attacks except for the purpose of self-defense, but despite the current situation the same country has now reverted to a regional power with strong military force in the world. on the contrary, due to this restriction, there is still a theory that the japanese armed forces may be stronger than the japanese army in the past, because some analysts believe that after the post-war constitution gave up the right to launch war, japan did not need to budget for attacking weapons, so concentrate on strengthening the development of defense capabilities. the most successful example is the japanese submarine. since the 1950s, the japanese government has been carefully investing in submarine development and improving technology. but unlike us navy submarines equipped with ground-attack missiles, japanese submarines only need to pay attention to underwater defenses, thus significantly reducing cost and r&d complexity. it can be known from the above successful cases that clear strategic guidance can make the country exert its maximum effectiveness under limited resources and budget. therefore, through the discussion of this article, we can understand japan, which is a maritime country with taiwan. under the same or similar threats, japan’s defense system and strategic direction, as taiwan’s future development, take the opportunity to determine its own future, and can make greater contributions to peace and security in the asia-pacific region, prosper and develop the values of freedom and democracy. conflicts of interest the author(s) report(s) no conflict(s) of interest(s). the author along are responsible for content and www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 8 published by scholink inc. writing of the paper. references john, k. e. (1967). japan, eye on 1970. foreign affairs, 47(2), 348-362. lewis, w. m., yopp, j. h., & schramm, j. h. l. (1978). use of hydroponics to maintain quality of recirculated water in a fish culture system. transactions of the american fisheries society, 107, 92-99. https://doi.org/10.1577/1548-8659(1978)107<92:uohtmq>2.0.co;2 martin, e. w. (1972). strategic thought and the u.s.-japan alliance. in j. w. morley (ed.), forecast for japan: security in the 1970s (pp. 35-84). princeton: princeton university press. randall, l. s. (1994). bandwagoning for profit: bringing the revisionist state back. international security, 19(1), 72-107. https://doi.org/10.2307/2539149 read, p., & fernandes, t. (2003). management of environmental impacts of marine aquaculture in europe. aquaculture, 226, 139-163. https://doi.org/10.1016/s0044-8486(03)00474-5 microsoft word ees-v2n1-p15.doc energy and earth science vol. 2, no. 1, 2019 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 15 original paper ammonia nitrogen pollution characteristics of natural rainfall in urban business district in southern china: a case study of chengdu city xintuo chen1, 2, yiyao wang1, chengyue lai1, 2, jia she1, 3, ke zhong1, 4, jiayang chen5, zhaoli wang1* 1 institute of water environment research, chengdu research academy of environmental protection science, chengdu, china 2 environmental monitoring and analysis laboratory, chengdu research academy of environmental protection science, chengdu, china 3 institute of drinking water safety, chengdu research academy of environmental protection science, chengdu, china 4 institute of watershed research, chengdu research academy of environmental protection science, chengdu, china 5 chengdu experimental primary school, chengdu, china *zhaoli wang, e-mail: 9755014@qq.com received: march 28, 2019 accepted: april 12, 2019 online published: april 23, 2019 doi:10.22158/ees.v2n1p15 url: http://dx.doi.org/10.22158/ees.v2n1p15 abstract chengdu city was chosen as the representative of southern cities in china in this work, characteristics of ammonia nitrogen (nh3-n) pollution in natural rainfall were analyzed by measuring the concentration in 15 natural rainfalls from april to september in 2017. the influence of ammonia emission from toilet vent of building on nh3-n pollution in rainfall was investigated, and the variation of total nh3-n pollutants and its influencing factors were expounded. the results showed that the average concentration of nh3-n in first rainfall was the highest, reaching 18.2mg/l, the average concentration of nh3-n in the subsequent 14 rainfalls was between 2.0 and 5.0mg/l, which is higher than grade v (≤2mg/l) of environmental quality standards of surface water (gb 3838-2002), and was an important source of nh3-n pollution in water. the concentration of nh3-n in natural rainfalls decreased with the increase of the distance between the sampling point and the toilet vent, indicating that the ammonia discharged from toilet exhaust is a major source of nh3-n pollution in urban atmosphere. the main factors affecting total nh3-n pollutants in natural precipitation include rainfall www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 16 published by scholink inc. intensity, rainfall duration and drought days. the total amount of nh3-n pollutants in surface runoff is less than that in natural rainfall. keywords southern city in china, natural rainfall, ammonia nitrogen pollution, total pollutant amount, pollution characteristics 1. introduction rainfall is a natural way to clean the atmosphere (wang & xu, 2009), so the air pollutants are an important source of pollution in rainwater. at present, the air pollution in cities of china has turned to the complex air pollution formed by fine particulate matter (pm2.5) and polluted gases (o3, sox, nox, nh3) (cao, 2014; samen j m et al., 2000; gao, 2012). some researches (ge et al., 2015)pointed out that water-soluble inorganic ions (wsii) like sox, nox and nh3 are important chemical components of pm2.5, secondary water-soluble inorganic ions like so4 2-, no3 -, nh4 + are the most important chemical species in the process of regional particulate matter pollution. among them, (nh4)2so4 and nh4no3 formed by reaction of the secondary pollutants such as sulfuric acid or nitric acid with nh3 have become the main water-soluble secondary pollutants in the atmosphere; yang (yang et al., 2007) observed atmospheric aerosols in jinan city and found that secondary ions in pm2.5 mainly exist in the form of (nh4)2so4 and nh4no3, nitrogen deposition has been taken into account as an important nitrogen source in the study of nitrogen cycle in river basins; huang (huang et al., 2016) studied nitrogen deposition in huanghuai plain from may 2008 to april 2012. it was found that nh3-n was the main type of nitrogen deposition and the proportion of nh3-n in nitrogen deposition was 6%-79%, with an average of 53%; zhu (zhu et al., 2015) considered 41 ecological research sites in china, and found that particulate nitrogen, ammonia nitrogen and nitrate nitrogen accounted for 24%, 40% and 33% of total nitrogen, respectively, indicating that ammonia nitrogen was the main component of atmospheric deposition; zheng (ge et al., 2017) studied three ammonia-rich areas in korea, and found that, (nh4)2so4 and nh4no3 were the main forms of water-soluble ions in pm2.5; the atmospheric (nh4)2so4 and nh4no3 can enter urban water body through rainfall, becoming an important source of nh3-n in water body, aggravating water eutrophication and destroying water ecosystem balance (ding et al., 2007; neal et al., 2006); wang jin jie (wang et al., 2014) carried out a 1-year study on nitrogen wet deposition in jinshui river basin. it was found that the concentration of total nitrogen in rainwater ranged from 0.24mg/l to 2.89mg/l, ammonium nitrogen, nitrate nitrogen and organic nitrogen accounted for 42.8%, 13.3% and 43.9% respectively, nitrogen concentration of rainwater decreased with the increase of rainfall, and was obviously diluted by rainfall; relevant studies (wang et al., 2014) indicated that compared with nitrate nitrogen, attached algae are easier to absorb and utilize ammonia nitrogen, leading to algae and other aquatic plants to proliferate in large numbers, resulting in blooms. in this work, chengdu is taken as a representative city of southern china to study the characteristics of ammonia nitrogen natural rainfall caused by air pollution sources. chengdu is a subtropical humid www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 17 published by scholink inc. monsoon climate area with mild climate, distinct seasons, long frost-free period, abundant rainfall and less sunshine. the annual total precipitation is 918.2mm, mainly in july to august (chengdu statistical yearbook, 2016). 15 natural rainfalls in chengdu city from april to september 2017 were collected and detected. the characteristics of nh3-n pollution in natural rainfalls were analyzed and the temporal and spatial variation of nh3-n pollution in rainfalls near toilet vents of buildings was emphasized. because there are no industrial enterprises in urban business area, and residential buildings or office buildings are the main structures, the ventilation outlets of the buildings are only toilet vents. total amount of nh3-n in rainfall and land surface runoff was also discussed. the purpose of this work is to provide theoretical support for source analysis and control of ammonia nitrogen pollution in water. 2. method 2.1 sample collection from the beginning of obvious precipitation to the end of the rainy season (april to september) in 2017, a total of 15 rainfall samples were collected in chengdu urban area. the natural rainfall sampling sites were located near the author's working unit, which is environmental protection building. the sampling sites of surface runoff process were located on the roads and pavement near the building. the sampling points were arranged as shown in figure 1 and the attributes of each point are shown in table 1. natural rainfall samples were collected by a 2000ml barrel. rainfall runoff samples are collected manually by pumping devices. figure 1. satellite map of sampling layout www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 18 published by scholink inc. table 1. attributes of sampling points serial number location sampling type pavement attribute rainfall runoff ① opening space in yard √ / ② parking lot ground √ √ cement ③ ground near north gate √ √ concrete ④ automobile lane √ √ asphalt ⑤ roof of building √ √ waterproof coating 2.2 monitoring and detection rainfall monitoring results were recorded with a dump rain gauge (jdz02-1) combined with real-time rainfall data published by chengdu meteorological bureau. the concentration of nh3-n was determined by nessler’s reagent spectrophotometry (hj535-2009). all samples were detected within 24 hours after collection. 3. result and discussion 3.1 variation of nh3-n concentration in natural rainfall the nh3-n concentration of all rainfall samples in chengdu urban area from april to september in 2017 was monitored and results are shown in figure 2. it can be seen that the concentration of nh3-n in the first rainfall in 2017 was the highest, reaching 18.2mg/l. according to environmental quality standards for surface water (gb3838-2002), it was far worse than grade v (≤2mg/l), which is the minimum requirement of water quality evaluation. figure 2. ammonia nitrogen concentration in natural rainfall (april to september in 2017) the first rainfall in 2017 occurred on april 22, around the grain rain day which is the 6th solar term of the 24 divisions of solar year in traditional chinese calendar. the higher concentration of nh3-n in www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 19 published by scholink inc. rainwater is due to the increase of motor vehicle travel in winter and frequent human in indoor activities like catering, bathing, heating, etc. the use of natural gas, fuel and other energy causes the increase of so2 and nox emissions, which promotes the formation and accumulation of (nh4)2so4 and nh4no3 in atmosphere. the lower temperature in winter is also conducive to the accumulation of nh4no3 in the atmosphere in granular form (meng et al., 2015). meanwhile, the atmosphere structure is stable in winter, pollutants are not easy to diffuse. therefore, during the first rainfall, accumulated (nh4)2so4 and nh4no3 in atmosphere dissolved into the rainwater, resulting in a higher concentration of nh3-n. nh3-n concentration decreased significantly in the following 14 rainfalls, ranging from 1.6mg/l to 5.1mg/l, with an average concentration of 3.1mg/l. it can be seen that atmospheric pollutants are the main source of ammonia nitrogen in natural rainfall. the first rainfall has a distinct effect on the scouring and purification of (nh4)2so4 and nh4no3 accumulated in winter atmosphere, which makes the concentration of nh3-n in subsequent rainfall decrease significantly. during the study period, nh3-n concentration of natural rainfall in chengdu city was mostly higher than that of grade v in standard gb3838-2002 (except for rainfall on july 21, august 20 and september 18).excessive ammonia nitrogen from rainfall flows into urban rivers, which may make water quality exceed the standard requirement and further cause the eutrophication of water body. 3.2 effect of toilet vent in buildings on nh3-n concentration of rainfall the formation of (nh4)2so4 and nh4no3 in the atmosphere depends on nh3 emissions. it is reported that the main sources of nh3 in atmosphere include livestock and poultry sources, nitrogen fertilizer application, synthetic ammonia production and human feces, accounting for 64%, 17%, 1% and 18% respectively (li, 2012). nh3 in chengdu urban area mainly comes from human excrement, almost all of which are discharged into atmosphere through toilet vents in buildings. therefore, sampling points were arranged near the vent (0, 5, 10 and 15m) on the roof of environmental protection building, as shown in ⑤ in figure 1, and nh3-n concentration in rainfall were detected. 3.2.1 characteristics of rainfall the concentration of pollutants in precipitation is influenced by many factors, and there is a large spatial-temporal difference (zhang et al., 2010; pu et al., 2010). in this study, nh3-n concentration in two rainfall events (may 13, 2017 and june 9, 2017) was monitored, and the effect of toilet vent on the concentration was analyzed. these two rainfall events belong to light and moderate rain and the rainfall amounts were 8.2 mm and 23.5 mm, respectively. the rainfall process line is shown in figure 3. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 20 published by scholink inc. figure 3. rainfall process line on may 13, 2017 and june 9, 2017 3.2.2 temporal and spatial variation of nh3-nconcentration in rainfall the variation of nh3-n concentration during rainfall process at different sampling points in two rainfall events on may 13, 2017 and june 9, 2017 is shown in figure 4. it can be seen that with the prolongation of rainfall duration at different places, nh3-n concentration of the rainfall decreases in varying degrees. at the beginning of rainfall, nh3-n concentration decreases significantly with time, but at the later stage, the concentration decreases slowly. this is due to the accumulation of ammonia nitrogen pollutants in atmosphere during earlier drought period, and the initial scouring effect of rainfall makes nh3-n concentration in the initial rainfall higher. however, ammonia nitrogen in atmosphere mainly comes from toilet vent in the late stage of rainfall, ammonia gas discharged directly or after secondary reaction dissolves into natural precipitation rapidly, so the nh3-n content in late rainfall is relatively lower. in addition, due to the moderate rain on june 9, 2017, the rainfall was larger and the initial scouring effect was stronger, so the ammonia nitrogen in rainfall decreased more obviously. figure 4. variation of nh3-n concentration in rainwater at different distance from toilet vent by analyzing the variation of nh3-n concentration with time, it was found that ammonia nitrogen in natural rainfall at the same sampling point showed a decreasing trend. as the distance from the toilet vent increased, the ammonia nitrogen in rainwater decreased, while the attenuation rate raised. in the case of larger rainfall, such as the moderate rain on june 9, 2017. nh3-n concentration in the middle and late stages was less affected by distance to the vent, and all the values tended to minimum. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 21 published by scholink inc. 3.3 total analysis of ammonia nitrogen pollutants because nh3-n concentration in rainwater can cannot reflect the pollution degree in urban water, the ammonia nitrogen pollution in rainfall and surface runoff was further assessed by the total amount of pollutants measurement method. 3.3.1 rainfall analysis three typical rainfalls on april 22, 2017, june 25, 2017 and august 13, 2017 were selected to analyze the total amount of ammonia nitrogen pollutants in rainwater and surface runoff. three typical rainfalls on april 22, 2017, june 25, 2017 and august 13, 2017 were selected to analyze the total amount of ammonia nitrogen pollutants in rainfall and surface runoff. according to the 24-hour hyetal grade standard, the three precipitations belong to light, moderate and heavy rain. on april 22, 2017, the rainfall intensity was small and the duration was short; on june 25, 2017, the rainfall intensity was low and the duration was long; on august 13, 2017, the rainfall was intense and lasting for a long time, each rainfall was 9.26, 21.25 and 34.33mm, respectively. 3.3.2 total ammonia nitrogen pollution analysis the total amount of ammonia nitrogen pollutants per unit area in natural rainfall was calculated by multiplying the average nh3-n concentration by amount of rainfall per unit area. the calculation results are expressed in grams per square meter as shown in table 2. table 2. total amount of ammonia nitrogen pollutant in three typical rainfalls in 2017 (g/m2) date opening space in yard (rainfall) parking lot ground (runoff) ground near north gate (runoff) automobile lane (runoff) roof of building (runoff) 2017/04/22 100.5 88.7 97.8 78.3 85.4 nh3-n loss rate 11.7% 2.7% 22.1% 15.0% average nh3-n loss rate 12.9% 2017/06/25 77.1 52.5 56.8 69.2 44.1 nh3-n loss rate 31.9% 26.3% 10.2% 42.8% average nh3-n loss rate 27.8% 2017/08/13 129.1 82.9 101.8 94.1 80.1 nh3-n loss rate 35.8% 21.1% 27.1% 38.0% average nh3-n loss rate 30.5% the total amount of ammonia nitrogen pollutants per unit area of surface runoff can be calculated by formula (1), as in wt= ∑ ct×pt t t=0 1000×a (1) wtis the total amount of pollutants per unit area, g/m2; ct is the concentration of pollutants in each period, mg/l; pt is the rainfall in each period, l; a is catchment surface area, m2. the total amount of ammonia nitrogen pollutants in natural rainfall and surface runoff at different www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 22 published by scholink inc. sampling points were calculated. the variation of nh3-n concentration in rainfall and surface runoff is shown in figure 5 with corresponding rain intensity. figure 5. variation of rainfall intensity and nh3-n concentration in rainfall and surface runoff according to results of monitoring and calculation, the total amount of ammonia nitrogen pollutants in natural rainfall is sorted as follows: june 25, 2017<april 22, 2017<august 13, 2017. on august 13, 2017, the rainfall intensity was strong and lasted for a long time, ammonia nitrogen pollutants in atmosphere was fully washed and absorbed by rainwater, the total amount of ammonia nitrogen pollutants in the rainfall was the largest. it also showed that rainfall intensity and duration were one of the main factors affecting total amount of ammonia nitrogen in rainfall. on the other hand, although the intensity of rainfall on june 25, 2017 was greater than that on april 22, 2017, because the rainfall on april 22 was the first rainfall in 2017, the accumulation of pollutants in the atmosphere was very large, www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 23 published by scholink inc. and the total amount of ammonia nitrogen pollutants dissolved in rainwater was relatively large, which also showed that the number of dry days before rainfall is another major factor affecting ammonia nitrogen in natural rainfall. moreover, ammonia nitrogen in rainwater is greater than that in surface runoff. the reason is that pollutants in rainwater was adsorbed on impervious surface during runoff, which reduces the total amount of ammonia nitrogen. during these 3 rainfall periods, the ammonia nitrogen of surface runoff at each sampling point has different degrees of loss compared with that in rainfall, as detailed in table 2. the average nh3-n loss rate in surface runoff was 12.9%, 27.8% and 30.5% respectively, which indicate that the greater rainfall intensity, the longer duration and runoff time, the more ammonia nitrogen can be lost in the process of runoff. 4. conclusion (1) among the 15 natural rainfalls monitored in 2017, the nh3-n concentration of 14 rainfalls was higher than the value of grade v (≤2mg/l) of environmental quality standards for surface water (gb3838-2002). nh3-n concentration of the first rainfall was the highest, reaching 18.2 mg/l, and then began to decrease in the subsequent 14 events, basically between 2.0 and 5.0 mg/l. ammonia nitrogen accumulated in the atmosphere is an important source of ammonia nitrogen pollutants in urban surface water. (2) nh3-n concentration in natural rainfall decreases with the increase of the distance between sampling point and toilet vent. ammonia discharged from toilet is an important source of ammonia nitrogen in urban atmosphere. (3) the main factors affecting the total amount of ammonia nitrogen pollutants in natural rainfall include rainfall intensity, time duration and the number of dry days before rainfall. because of the adsorption effect on ground surface, the total amount of ammonia nitrogen pollutants in surface runoff is less than that in natural rainfall. urban ground surface cleaning and emission reduction are the fundamental ways to reduce pollution. references cao, j. j. (2014). pm2.5 and environment. beijing: science press. din, g. y. et al. (2007). simulation study on algal dynamics based on ecological flume experiment in taihu lake. ecological engineering, 31(1), 200-206. https://doi.org/10.1016/j.ecoleng.2007.06.013 gao, x. m. (2014). characterization and sources of pm2.5 water-soluble ions in typical areas of china. doctor’s thesis. shandong university, jinan, china. ge, l. l. et al. (2017). characteristics and sources apportionment of water-soluble ions in pm2.5 of wenzhou, zhejiang province. journal of zhejiang university (science edition), 44(1), 112-119. www.scholink.org/ojs/index.php/ees energy and earth science vol. 2, no. 1, 2019 24 published by scholink inc. ge, s. et al. (2015). characteristics analysis of haze water-soluble ion in nanjing in autumn. environmental science & technology, 38(2), 99-104. huang, p., zhang, j. b., & ma, d. h. (2016). atmospheric deposition as an important nitrogen load to a typical agro-ecosystem in the huang-huai-hai plain. 2. seasonal and inter-annual variations and their implications (2008-2012). atmospheric environment, 1(129), 1-8. https://doi.org/10.1016/j.atmosenv.2016.01.015 li, x. y., & li, h. p. (2012). emission and distribution of nh3 and nox in china. china environmental science, 32(1), 37-42. meng, c. c. et al. (2015). pollution characteristics and source apportionment of water-soluble inorganic ions in pm2.5 in handan city. acta scientiae circumstantiae, 35(11), 3443-3451. neal, c. et al. (2006). chlorophy ⅱ-α in the rivers of eastern england. science of the total environment, 365(1), 1742-1749.https://doi.org/10.1016/j.scitotenv.2006.02.039 pu, w. w. et al. (2010). characteristics and impact factors of acid rain in beijing. journal of applied meteorological science, 21(4), 464-472. samen, j. m. et al. (2000). fine particulate air pollution and mortality in 20 us cities, 1987-1994. new england of medicine,343(24), 1742-1749.https://doi.org/10.1056/nejm200012143432401 wang j. j. et al. (2014). wet deposition of atmospheric nitrogen of jinshui watershed in the upper hanjiang river. environmental science, 35(1), 66-72. wang, w. x., & xu, p. j. (2009). research progress in precipitation chemistry in china. progress in chemistry, 21(2), 266-281. wang, x. y., & zhong, s. (2014). study on the changes of nh3-n and tn of different seasons in taihu lake basin. journal of anhui agriculture science, 42(25), 8712-8713. yang, l. x. et al. (2007). study on the water-soluble ions in fine particle matter and the long-range transport of air masses in the city of jinan. journal of shandong university: engineering science edition,37(4), 98-103. zhang x. m. et al. (2010). research progress of acid precipitation in china. research of environmental science, 23(5), 527-532.https://doi.org/10.1080/14786410600800165 zhu, j. x. et al. (2015). the composition, spatial patterns and influencing factors of atmospheric wet nitrogen deposition in chinese terrestrial ecosystems. science of the total environment, 1(511), 777-785. https://doi.org/10.1016/j.scitotenv.2014.12.038 energy and earth science vol. 4, no. 3, 2021 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 original paper comparison of biogas concentrations in various environmental conditions and determination of the optimal period of its production at environment temperature edmond demollari 1* , etleva jojic 1 , enkeleda sallaku 2 , valdete vorpsi 1 , erta dodona 1 & olsid mema 1 1 department of agronomic sciences, agricultural university of tirana, tirana, albania 2 department of animal sciences, agricultural university of tirana, tirana, albania * edmond demollari, department of agronomic sciences, agricultural university of tirana, tirana, albania received: february 23, 2021 accepted: march 8, 2021 online published: august 23, 2021 doi:10.22158/ees.v4n3p1 url: http://dx.doi.org/10.22158/ees.v4n3p1 abstract albania, as a part of western balkan, has a variety of climate systems. this type of climate has a closed connection with waste treatment process. the biogas volume produced by the experimental environmental was 0.6 m 3 . the maximum methane concentration in biogas was reached at 55.8%/volume. the enclosed area (in oval circle) is another indicator of this system. this area extends over the period from 14.08.2018 until 26.08.2018 (12 days). the biomethane maximum biogas concentration reached 53.5 %/vol. up to 55.8% vol. the concentration drop was 4.2 %/vol. the main factor was the temperature. in the period of maximum durability the temperatures were minimum 30°c and maximum 42°c. another contributing factor was the inoculum. since inoculum was made from the treatment of four types of waste of different nature, then the concentration of microorganisms was higher. the purpose of the comparison between the two experiments is the sustainability of biogas production as well as the biomethane concentration biogas concentration on waste treatment. environmental temperature was studied in three different regions of albania: shkodra, tirana and vlora. the observations showed that the region of vlora has the longest period of average daily temperature (june 14 th to october 1 st ). keywords thermal equilibrium, performance of biogas, analytical relation www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 3, 2021 2 published by scholink inc. 1. introduction albania is a country that lies in balkan peninsula, in south-eastern europe. albania has two different climate zones. the coast of albania has a mediterranean climate. this area has long hot summers and wet but mild winters. inland is a continental climate (https://weather-and-climate.com/average-monthly-rainfall-temperature-sunshine-in-albania). however, winters here are severe with a high chance of snow. albania’s climate is strongly influenced by the country’s location. temperatures are affected from both the adriatic and the albanian alps. heat waves can disappear quickly by sometimes very heavy rain and thunderstorms, with the daily temperature falling by more than ten degrees within a day (https://weather-and-climate.com/average-monthly-rainfall-temperature-sunshine-in-albania). biodegradation rates in the bio-toilet system are affected, among several factors, by environmental conditions such as temperature, moisture content, oxygen availability and ph. temperature is one of the most important factors affecting microbial growth and biological reactions. temperature can exert an effect on biological reactions in two ways: by influencing the rates of enzymatically catalyzed reactions and by affecting the rate of diffusion of substrate to the cells (grady, daigger & lim, 1999). of all the factors affecting the yield of biogas temperature of the digester environment is the most important. the temperature of the region decides the group of methanogenic bacteria that shall be stimulated for production of methane (ahuja et al., 2016). temperature control therefore becomes an important design criterion while designing anaerobic biogas digesters. use of digester insulation, maintaining temperature in the digester via heat exchangers, heating elements, placing digesters inside a water bath, and injecting steam in the digester are some of the means of maintaining temperature of the digester in its operating range (energypedia, “digesterheating” [online]; waste digester design instructor materials). in practice, sudden environmental changes, e.g., dramatic increases or drops in temperature, may cause severe disturbances in all parameters of the process, and the system requires a long period of time to adapt to a stable state. furthermore, the temperature has a significant impact on the growth and metabolism of microorganisms and the interactions between the microbial groups (alvarez & lidén, 2008; el-mashad, zeeman, van loon, bot & lettinga, 2004; xiong, chen, wang & shi, 2012; rademacher, nolte, schonberg & klocke, 2012). 2. material and methods for the construction of the plant at environmental temperature for the production of biogas in albania, the average daily temperatures for the areas under study were carefully observed. this was one of the main steps in order to continue further. the average daily temperatures for the annual period 2013-2017 were taken by the meteorological center of the albanian air force. part of the metodology is and comparison of biogas production between two experimental proves: mixing with inoculum containing and mixing without inoculum containing, under the same temperature-pressure conditions. the period in which the environmental experiment was applied, was july-september 2018. the regions included in www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 3, 2021 3 published by scholink inc. the study, showed in figure 1, were: shkodra, tirana and vlora as part of the western lowlands of the republic of albania. the western lowlands represent the largest plain province and is one of the largest plains of the balkan peninsula. the main constituent units of the western lowlands are: shkodra lowland, field between lezha city and river of shkumbin, hilly ridge of rodon-krrabë, field of elbasan, dumre-darsia plateau, field of myzeqe and hills of mallakastra. figure 1. included areas in the study in republic of albania 3. results and discussion the predicted experimental time period should be applied up to 35 days but the experiment lasted for up to 50 days. the reason was for observing the production capacity of the biogas mix. according to attar, mhetre, and shaale (1998) for a population of 28.6 million birds, produces 1575.5 million kg/year of waste, biogas produced is ≈116.6 million m 3 /year (attar, mhetre & shawale, 1998). so, based on the above data, 1 kg of poultry treated in anaerobic digester produces 2.02 x 10 -4 m 3 /day of biogas. based on the regional statistical yearbook (2016), the ministry of agriculture, rural development and water administration of albania, 1 head (cattle) produces 37.19 kg of waste per day and 1 bird produces 0.06 kg of waste per day (regional statistical yearbook of albania, 2016). www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 3, 2021 4 published by scholink inc. figure 2. temperature measurement frequency in greenhouse environment with datalogger sensor figures 2 and 3 give temperature differences in their values (chart 1: min 20°c and max 38°c; chart 2: min 30°c and max 42°c). these temperature changes are due to the achievement of thermal equilibrium (outside the anaerobic environment) and the endothermic processes (heat-absorbing processes) of the microorganisms inside the mixture. the experiment gives us the “right” to think that we can predict the performance of biogas production from agricultural waste in function of environmental temperatures, taking linear equations composed of three variables: figure 3. temperature in anaerob environmental and its average temperature m (methane) t1 (greenhouse temperature) t2 (temperature in anaerobic environment) www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 3, 2021 5 published by scholink inc. figure 4. relation between two applied temperatures the relationship between the temperatures: in the greenhouse environment and in the induced temperature environment is given by equation 1, showed in figure 4. t2 = 0.888 t1 + 4.9 (1) equation 1 represents the analytical relation between t1 and t2. the equation 2 generated by the graphio-analytical relation, showed in figure 5, represents the relation between the temperature inside the digester in the function of the methane produced. m = 0.202 t2 + 31.33 (2) figure 5. performance of methane production as a function of temperatures in the anaerobic environment the combination of equations (1) and (2) enables us to establish the analytical link between produced biogas and greenhouse temperature, ie between m and t1 variables. www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 3, 2021 6 published by scholink inc. generating equation 3 from two equations 1 and 2 at the same time allows us to predict how the biogas production performance can be in the future (always in “greenhouse” environmental conditions). m = 0.179 t1 + 32.319 (3) the biogas volume produced by the experimental environmental was 0.6 m 3 . the maximum methane concentration in biogas was reached at 55.8%/volume. chart 5 shows a steady performance in biogas production from the bes system (batch environmental system) (inoculum + substrate), and more to biomethane biogas concentration. the enclosed area (in oval circle) is another indicator of this system. this area extends over the period from 14.08.2018 until 26.08.2018 (12 days). the biomethane maximum biogas concentration reached 53.5 %/vol. up to 55.8% vol. this showed the maximum sustainability achieved in biogas production in “greenhouse” environmental conditions but this period did not last long. the decrease in concentration was observed between 26.08.2018 and ongoing. the concentration drop was 4.2%/vol. the main factor was the temperature. in the period of maximum durability the temperatures were minimum 30°c and maximum 42°c. another contributing factor was the inoculum. since inoculum was made from the treatment of four types of waste of different nature, then the concentration of microorganisms was higher. the purpose of the comparison between the two experiments is the sustainability of biogas production as well as the biomethane concentration biogas concentration on waste treatment. figure 6. concentration of biomethane in biogas produced by inoculum-substrate mixture under “greenhouse” environmental conditions (bes system) www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 3, 2021 7 published by scholink inc. figure 7. concentration of biomethane in biogas produced under “greenhouse” environmental conditions, without inoculums “participation” (bes system, dissertation “evaluation and optimization of indicatorial parameters in biogas production from agricultural waste, in albanian conditions”, 2019, experiment 2, page 80) figure 7 shows the higher biomethane concentration on biogas, the higher its calorific point. despite the maximum concentration in the bes system, the second experiment is 58.6%/vol., i.e., 2.8%/vol. ch4 more, this does not mean that the system is the best. his persistence in concentration is small. the concentration dropped by almost 8%/vol. after six days. the bes system (inoculum-based) showed high concentration stability (about 12 days). from this reasoning it appears that the obtained biogas based on inoculum has a more consistent consistency in focusing on “greenhouse” environmental conditions than biogas that does not include inoculum. we see that the maximum mean temperature reached 27.5°c while the minimum average temperature reached 22°c. this showed that this period was the optimal biogas production period from the development of our environmental experiment (without induced temperature). this was reflected in green zone (figure 8). in the green zone we distinguish three zones (area 1 above 27.5°c, area 2 or intermediate area between 22°c and 27.5°c, area 3 below 22°c). the area in which the experiment with environment temperature can operate is area 2. this is the optimal area of our experiment. area 1 is the surface where we would like the experiment to develop because the values are closer to 37°c but this does not depend on us and are very favorable for biogas production. referring to area 3, it is the area in which the experiment can be developed but the biomethane concentration in biogas reaches low values, so the environment would be inadequate. if we set the average maximum temperature value and the average minimum temperature value in the average daily temperature graphs observed over a 5 year period (2013-2017) of shkodra, tirana and vlora regions (refer to figures: 9, 10 and 11), we will note that periods of biogas production would change. from this situation it turns out that the geographic position of these regions (as part of the western lowlands in albania) and the large number of livestock farms is the reason we considered www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 3, 2021 8 published by scholink inc. these three cities as part of our study. based on regions of shkodra, tirana and vlora, we see that the region of vlora has the longest period of time with the average daily temperature (june 14 to october 1). from this reasoning emerges that vlora as part of the western lowland is more favorable for the erection and erection of digestive plants for the production of biogas at environment temperature compared to the other two cities. the boundaries of the periods of time were determined by the small differences in the amplitude of the five years taken in the study. figure 8. determining the minimum average temperature and the maximum average temperature during the period of conducting the environmental experiment fugure 9. determining the optimal period for biogas production at environmental temperatures in the city of shkodra www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 3, 2021 9 published by scholink inc. figure 10. determining the optimal period for biogas production at environmental temperatures in the city of tirana figure 11. determining the optimal period for biogas production at environmental temperatures in the city of vlora 4. conclusions a) biogas production in terms of environmental temperatures has a direct relationship, which was observed in production downturns whenever there was a decrease in external temperatures. b) inoculum-based biogas, in “greenhouse” environmental conditions, showed a more constant concentration of ch4 (about 12 days) than biogas obtained from simple mixing. c) the most optimal period of time, considering the duration of the weather, was the region of vlora (14 june to 1 october) compared to the regions of tirana and shkodra. www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 3, 2021 10 published by scholink inc. based on above points a, b and c, it turns out that: the most constant concentration of ch4 in the produced biogas is inoculum base and the most optimal time period for the duration of the temperature is the region of vlora. the region of vlora (part of albania westlowland) offers the suitable area to implement biogas power plant as alternative fuel for the future. references ahuja et al. (2016). iioabj, 7(11), 60-67. alvarez, r., & lidén, g. (2008). the effect of temperature variation on biomethanation at high altitude. bioresour. technol., 99, 7278-7284. https://doi.org/10.1016/j.biortech.2007.12.055 attar, y., mhetre, s. t., & shawale, m. d. (1998). biogas production enhancement by cellulytic strains of actinomycetes. biogas forum, 1(72), 11-15. bes system. (2019). dissertation “evaluation and optimization of indicatorial parameters in biogas production from agricultural waste, in albanian conditions”, 2019. in experiment 2 (p. 80). el-mashad, h. m., zeeman, g., van loon, w. k., bot, g. p., & lettinga, g. (2004). effect of temperature and temperature fluctuation on thermophilic anaerobic digestion of cattle manure. bioresour. technol., 95, 191-201. grady, c. p. l., daigger, g. t., & lim, h. c. (1999). biological wastewater treatment (2nd ed.). new york, usa: marcel dekker inc. energypedia. (n.d.). digesterheating. retrieved from https://energypedia.info/wiki/digester_heating rademacher, a., nolte, c., schonberg, m., & klocke, m. (2012). temperature increases from 55 to 75 degrees c in a two-phase biogas reactor result in fundamental alterations within the bacterial and archaeal community structure. appl. microbiol. biotechnol., 96, 565-576. https://doi.org/10.1007/s00253-012-4348-x regional statistical yearbook of albania. (2016). xiong, h., chen, j., wang, h., & shi, h. (2012). influences of volatile solid concentration, temperature and solid retention time for the hydrolysis of waste activated sludge to recover volatile fatty acids. bioresour. technol., 119, 285-292. https://doi.org/10.1016/j.biortech.2012.05.126 https://doi.org/10.1016/j.biortech.2007.12.055 https://doi.org/10.1007/s00253-012-4348-x https://doi.org/10.1016/j.biortech.2012.05.126 energy and earth science vol. 6, no. 3, 2023 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 21 original paper the venusian insolation atmospheric topside thermal heating pool philip mulholland 1* & stephen paul rathbone wilde 2 1 mulholland geoscience, edinburgh, uk 2 private researcher, wirral, uk * philip mulholland, mulholland geoscience, edinburgh, uk received: august 13, 2023 accepted: august 23, 2023 online published: september 1, 2023 doi:10.22158/ees.v6n3p21 url: http://dx.doi.org/10.22158/ees.v6n3p21 abstract a 1 metre increment modelled pressure profile is used to study the troposphere of venus from the surface to the lower stratosphere. using a troposphere model lapse rate profile as the constraint on cooling by vertically convecting air, the modelled height of the tropopause convection limit is a close match to the level of the observed static atmosphere height for the 250 kelvin freezing point level of 75% by weight of concentrated sulphuric acid, the primary condensing volatile in the venusian atmosphere. this relationship suggests that the observed albedo of venus is a response to and not a cause of planetary atmospheric solar radiant forcing. using the thermal lapse rate for the troposphere of venus in its top-down mode of application, the depth below the tropopause that solar irradiance is able to achieve effective heating of the venusian atmosphere is established. this radiant quenching depth delineates a pool of upper tropospheric air that both captures and responds to solar radiant forcing. consequently, this top of the troposphere insolation forcing induces a process of full troposphere adiabatic convective overturn and delivers solar heated air to the ground via the action of forced air descent in the twin polar vortices of venus. keywords venus atmosphere, boyle’s law, spherical shells, thermal heating pool, adiabatic convection www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 22 published by scholink inc. 1. introduction close proximity observations of the planet venus by the nasa mariner 10 space probe in 1974 have shown that its upper atmosphere displays a set of cloud bands that are part of a global atmospheric circulation system, which connects the solar zenith point of maximum solar radiant forcing to both polar vortices of the planet (figure 1). figure 1. nasa 1974 mariner 10’s portrait of venus this paper develops the results of the application of the dynamic-atmosphere energy-transport ((daet) mathematical model to a study of the climate of venus (mulholland & wilde, 2020) and addresses the following two issues: 1) that the intensity of the dim sunlight is too weak to fully energise the surface of the planet venus at the base of a 63.4 km thick troposphere. 2) consequently, the temperature at the base of the atmosphere of 699 kelvin (426 o c) (singh, 2019, pp. 1-5) has a value that far exceeds the effective solar radiative thermodynamic temperature of the surface insolation received by venus (table 1). www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 23 published by scholink inc. table 1. venus lit hemisphere illumination interception geometry location latitude (degrees) elevation angle (degrees) sine angle solar power intensity (w/m2) effective flame temperature (kelvin) quenching limit height (km) air pressure (hpa) north pole 90.00 0 0.00000000 0.00 z1: heating limit  86.43 3.57 0.06226276 37.25 160.10 110.000 z1: 85 5 0.08715574 52.15 174.14 88.092 0.37 z1: 80 10 0.17364818 103.89 206.89 76.617 5.84 z1: 75 15 0.25881905 154.85 228.60 70.502 20.89 z1: 70 20 0.34202014 204.63 245.10 64.669 64.11 z1: 65 25 0.42261826 252.85 258.41 61.065 123.05 z5: hemisphere average flux 60 30 0.50000000 299.15 269.51 58.461 192.90 z1: 55 35 0.57357644 343.17 278.92 56.454 269.32 z1: 50 40 0.64278761 384.58 286.97 54.850 348.82 z1: 45 45 0.70710678 423.06 293.90 53.540 428.56 z1: 40 50 0.76604444 458.32 299.84 52.461 505.92 z1: 35 55 0.81915204 490.10 304.91 51.570 578.81 z1: 30 60 0.86602540 518.14 309.18 50.839 645.33 z1: 25 65 0.90630779 542.24 312.71 50.247 703.99 z1: 20 70 0.93969262 562.22 315.55 49.798 751.53 z1: 15 75 0.96592583 577.91 317.73 49.474 787.52 z1: 10 80 0.98480775 589.21 319.27 49.244 813.95 z1: 5 85 0.99619470 596.02 320.19 49.107 830.05 z1: equator 0 90 1 598.30 320.50 49.061 835.52 illumination intensity versus solar elevation at its base venus has a dense atmosphere with a value of 69.69 kg/m 3 (table 2), while this is far less than the density of liquid water (1,000 kg/m 3 ), the oceans of earth do provide a model as to how the topside of a planetary atmosphere can be heated. on earth the photic zone is that shallow part of the ocean (typically less than 200 m water depth) where sunlight energy is absorbed and the water is heated. on venus the average post-albedo insolation received by the lit hemisphere is 299 w/m 2 , which equates to a thermodynamic temperature of 269.5 kelvin (-3.6 o c) (figure 2). this average intensity will apparently provide heating for only the upper 5 km of the troposphere at heights above 58.4 km, where the lapse rate reduced air temperature is below the 269.5 kelvin value (figure 3). www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 24 published by scholink inc. figure 2. venus lit hemisphere illumination interception geometry at depths in the atmosphere below this average insolation level the average energy contained in the sunlight is less than the ambient temperature of the surrounding air, so no heating is apparently possible. however, and perhaps more importantly the local intensity of the insolation at solar zenith has sufficient power to heat the venus atmosphere down to a level of 49 km, in a column that is 14.4 km thick (figure 3). figure 3. venus atmospheric solar radiant thermal heating pool www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 25 published by scholink inc. it is this concentration of energy at the solar zenith, heating the upper air that creates the bow-wave disruptor observed in the centre of the blue disk, as the thermal impact of the solar zenith travels around the planet (figure 1). the energy imparted by the sun into that zenith induced bow-wave powers the circulatory system of the upper atmosphere (limaye, 2010). so, just like the sun heats the top of the earth’s oceans, the sun clearly heats the top of the venus atmosphere. however, unlike water in the earth’s oceans the heated topside atmosphere of venus is a compressible gas held at high elevation in a gravity field. this has clear implications for the process of surface heating by full troposphere mass-motion solar forced convection overturn of a compressible gas in the presence of a gravity field. in order to study this circulation process using the daet climate model a pressure profile model for the venus troposphere at 1 metre increments has been created. this calculation has been applied from the surface to the lower stratosphere, a modelled vertical height of 100 kilometres (mulholland & wilde, 2021). two equations of state are used to achieve this objective, these are the pressure, volume, temperature (pvt) version of boyle’s law, and the application of newton’s gravity law of spherical shells, used to calculate the reduction in strength of the gravity field as the height above the surface of venus increases. for the purpose of this study a set of four linked predictive lapse rate equations based on published data has been created (justus & braun, 2007). these equations are used as the fundamental temperature control of the tropospheric pressure profile. the temperature data that controls these equations is calibrated to a surface datum global average temperature for venus of 699 kelvin (singh, 2019, pp. 1-5). 2. method the spreadsheet analysis of the pressure profile of the venusian atmosphere presented here is built on the following baseline parameters (williams, 2023): 1) the surface pressure measured in pascal. 2) the surface temperature measured in kelvin. 3) the molecular weight of the venus atmosphere measured in g/mole. 4) the surface gravity of venus measured in m/s 2 . 5) the planetary mass of venus in kg. 6) the mean radius of venus in metres. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 26 published by scholink inc. figure 4. venusian atmosphere: temperature versus altitude 7) a set of four predictive temperature lapse rate equations for the atmosphere of venus based on published data (justus & braun, 2007) measured in k/m and corrected to a surface datum value of 699 kelvin (singh, 2019, pp. 1-5) (figure 4). 8) using the two physical relationships of boyle’s gas law, and newton’s spherical shell gravity law, a pressure profile is created for the atmosphere, applying the predictive lapse rate equations as temperature control over the relevant height intervals (figure 5). the predictive lapse rate equations used in the pressure profile model are listed in table 2. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 27 published by scholink inc. table 2. predictive lapse rate equations item height (m) predictive temperature lapse rate equation temperature (kelvin) pressure (hpa) density ρ (kg/m3) lr1: lapse rate: start of troposphere equation 0 =-7.967*i2/1000+699 699.000 93,219.00 69.69140601 lr1: lapse rate tie point: end of troposphere equation 39,220 =-7.967*i39222/1000+699 386.534 3,001.63 4.058083903 lr2: lapse rate tie point: start of solar heating convection equation 39,221 = -6.71*i39223/1000 + 649.7 386.527 3,001.27 4.057677378 lr2: lapse rate tie point: end of solar heating convection equation 50,000 = -6.71*i50002/1000 + 649.7 314.200 729.81 1.213822584 lr2: lapse rate tie point: start of tropopause convection overshoot equation 50,000 = -6.71*i50002/1000 + 649.7 314.200 729.81 1.213822584 lr2: lapse rate: end of tropopause convection overshoot equation 70,000 = -6.71*c20032/1000 + 649.7 180.000 16.67 0.048388192 lr3: lapse rate tie point: start of tropopause breaking equation 50,001 = 0.092*(i50003/1000)^2 15.26*i50003/1000 + 847.2 314.194 729.70 1.213669421 lr3: lapse rate tie point: end of tropopause breaking equation 70,477 = 0.092*(i70479/1000)^2 15.26*i70479/1000 + 847.2 228.686 20.99 0.04796827 lr4: lapse rate tie point: start of stratosphere equation 70,478 =( 0.0027*(i70480/1000)^3 0.5809*(i70480/1000)^2 + 38.611* (i70480/1000)537.31)+(0.0146*(i70480/1000)^2 + 1.594*(i70480/1000) 54.84) 228.683 20.99 0.047959369 lr4: lapse rate: end of stratosphere equation 100,000 =( 0.0027*(i100002/1000)^3 0.5809*(i100002/1000)^2 + 38.611* (i100002/1000) 537.31)+(-0.0146*(i100002/1000)^2 + 1.594*(i100002/1000) 54.84) 173.350 0.01588 4.78577e-05 the datum parameters used for the pressure profile analysis are listed in table 3. table 3. datum values surface pressure 92 atmospheres control used at l2 surface pressure 9,321,900 pascal area 1 square metre force 9,321,900 newton used in column t universal gravitational constant 6.67430e-11 m 3 .kg -1 .s -2 boltzmann constant 1.38065e-23 j/k avagadro constant 6.02214e+23 mol-1 varied in column t venus gravity 8.87039 m/s2 used at u2 atmospheric mass 1,050,901 kg used in column m molecular weight 43.45 g/mol used at m2 surface density 69.691 kg/m3 notional qc check total "thickness" (scale height) 15,079 m control used at j2 surface temperature 699 kelvin stp temperature 273.15 kelvin stp temperature 0 celsius used in column j lr1: lapse rate (troposphere) predictive equation k/m used in column j lr2: lapse rate (tropopause) predictive equation k/m used in column j lr3: lapse rate (stratosphere) predictive equation k/m z9: pressure tropopause 100 hpa or mbar z9: tropopause 100 hpa 62.232 km z9: tropopause 100 hpa 253.84 kelvin air properties earth stp venus units pressure 101,325 9,321,900 pascal pressure 1,013 93,219 hpa or mbar temperature 273.15 699 kelvin temperature 0 425.85 celsius volume 22,414 623.458 cm3 density 1.939 69.691 kg/m3 lapse rate convection troposphere 7.270 k/km datum values key pad www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 28 published by scholink inc. 3. result in order to verify the daet climate model of venus, the model was first calibrated against the new surface datum temperature of 699 kelvin (singh, 2019, pp. 1-5). this process was achieved by reducing the energy intensity flux partition ratio to an atmosphere retained percentage of 98.071%, down from the previously published value of 99.1138% (mulholland & wilde, 2020, pp. 20-35). this adjustment is in line with the modelling concept that the average global surface temperature of a planet is a function of the energy flux partition ratio between the retained atmospheric energy in the troposphere, and the radiant energy loss to space from the stratosphere (table 4). table 4. adiabatic model of venus showing internal energy recycling for both hemispheres the key results from the boyle’s law pressure model analysis for the atmosphere of venus (mulholland & wilde, 2021) are listed in table 5 and displayed in figure 5. these results include the following: 1) the average post-albedo irradiance for the lit hemisphere of venus is 299 w/m 2 , this intensity (table 1, z5) converts to a thermodynamic temperature of 269.5 kelvin (-3.6 o c). this temperature occurs at an altitude of 58.46 km and a pressure of 192.9 hpa. by geometry the average intensity value of 299 w/m 2 also occurs at a solar elevation angle of 30 o (figure 2). www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 29 published by scholink inc. 2) the post-albedo solar zenith irradiance for venus is 598.3 w/m 2 , this maximum possible intensity (figure 3, z1) converts to a thermodynamic temperature of 320.5 kelvin (47.3 o c). this temperature occurs at an altitude of 49.06 km and a pressure of 835.5 hpa (table 5). table 5. predicted pressures item height (m) predictive temperature lapse rate equation temperature (kelvin) pressure (hpa) density ρ (kg/m3) pe =mgh (joules) z6: mean air temperature (699 kelvin) 0 =-7.967*i2/1000+699 699.000 93,219 69.69140601 0 z1: solar zenith (albedo applied) 49,061 = -6.71*i49063/1000 + 649.7 320.501 835.52 1.362326292 583,372 z5: space incoming captured radiation (w/m2) 58,461 = 0.092*(i59315/1000)^2 15.26*i59315/1000 + 847.2 269.512 192.90 0.374026892 190,285 z8: night tropopause 63,240 = -6.71*i63242/1000 + 649.7 225.360 76.31 0.176958051 97,234 z9: tropopause ceiling 100 hpa, 235.84 kelvin, 62.232 km 62,232 = 0.092*(i62234/1000)^2 15.26*i62234/1000 + 847.2 253.839 100 0.205873161 111,356 z10: mean tropopause 63,337 = -6.71*c13369/1000 + 649.7 224.709 74.83 0.174025191 95,766 z11: lit tropopause 63,433 = -6.71*c13465/1000 + 649.7 224.065 73.39 0.171162378 94,331 z12: dark side radiant partition is 1.0929% (w/m2) 71,156 =( 0.0027*(i71158/1000)^3 0.5809*(i71158/1000)^2 + 38.611* (i71158/1000)537.31)+(0.0146*(i71158/1000)^2 + 1.594*(i71158/1000) 54.84) 226.299 18.33 0.042334801 26,106 z13: mean radiant exit temperature (kelvin) 71,062 =( 0.0027*(i71064/1000)^3 0.5809*(i71064/1000)^2 + 38.611* (i71064/1000)537.31)+(0.0146*(i71064/1000)^2 + 1.594*(i71064/1000) 54.84) 226.631 18.68 0.043076419 26,529 z14: space outgoing radiation balance (w/m2) 71,062 =( 0.0027*(i71064/1000)^3 0.5809*(i71064/1000)^2 + 38.611* (i71064/1000)537.31)+(0.0146*(i71064/1000)^2 + 1.594*(i71064/1000) 54.84) 226.631 18.68 0.043076419 26,529 z15: vacuum planet equation expected te of venus (226.627 kelvin) 71,063 =( 0.0027*(i71065/1000)^3 0.5809*(i71065/1000)^2 + 38.611* (i71065/1000)537.31)+(0.0146*(i71065/1000)^2 + 1.594*(i71065/1000) 54.84) 226.627 18.68 0.043068467 26,525 z16: lit side radiant partition is 1.0929% (w/m2) 70,985 =( 0.0027*(i70987/1000)^3 0.5809*(i70987/1000)^2 + 38.611* (i70987/1000)537.31)+(0.0146*(i70987/1000)^2 + 1.594*(i70987/1000) 54.84) 226.902 18.97 0.043692829 26,880 z17:r rising air droplet cloud tops (260 kelvin) 58,077 = -6.71*c9600/1000 + 649.7 260.003 201.35 0.404689223 204,558 z17:s stable air droplet cloud tops (260 kelvin) 60,673 = 0.092*(i60675/1000)^2 15.26*i60675/1000 + 847.2 260.002 131.82 0.264950232 139,792 z18:r rising air latent heat freezing point of 75%wt h2so4 (250.0 kelvin) 59,568 = -6.71*c9600/1000 + 649.7 249.999 154.26 0.322448865 167,091 z18:s stable air freezing point of 75%wt h2so4 (250.0 kelvin) 63,266 = 0.092*(i63268/1000)^2 15.26*i63268/1000 + 847.2 249.999 82.97 0.173424014 95,331 www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 30 published by scholink inc. figure 5. venusian tropopause: temperature versus altitude 3) the daet adiabatic climate model of venus predicts for the lit hemisphere a thermal emission intensity (table 4, z16) of 150.4 w/m 2 and a thermodynamic temperature of 226.9 kelvin (minus 46.3 o c). this temperature occurs at an elevation of 70.99 km and at a pressure of 19 hpa (table 5). 4) the daet adiabatic climate model of venus also predicts for the dark hemisphere a thermal emission intensity (table 4, z12) of 148.75 w/m 2 and a thermodynamic temperature of 226.3 kelvin (minus 46.8 o c). this temperature occurs at an elevation of 71.15 km and at a pressure of 18.33 hpa (table 5). 5) the modelled height of the venusian droplet cloud planetary veil (z17: s) occurs at an elevation of 60.67 km and a temperature of 260 kelvin (young, 1973, pp. 564-582) with an associated pressure of 18.33 hpa (table 5). 6) the measured freezing point of 75% wt h2so4 (z18:s) is 250 kelvin (-23 o c) (young, 1973, pp. 564-582). this temperature is found at a model altitude of 63.27 km, and a pressure of 83 hpa (table5). this near association between the stable air freezing point of concentrated sulphuric acid, the main condensing volatile in the venus atmosphere, and the daet modelled height of the convection tropopause warrants further study. solid aerosol particles are efficient thermal emitters and can enhance atmospheric thermal radiation loss to space through the transparent lower stratosphere (figure 4). www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 31 published by scholink inc. 3.1 the energy consequence of air convection in a gravity field at the modelled convection tropopause of venus, over 63.3 km above the planet’s surface (table 5, z10), a cubic metre of venusian air has a mass of 174 g and possesses a potential energy of 95.7 kilojoules. all air mass held aloft in a gravity field contains a considerable quantity of potential energy. on descent to the surface this air will undergo adiabatic heating and consequent air temperature rise as it falls towards the planet’s surface. in doing so it loses potential energy by the process of conversion to kinetic energy (figure 6). figure 6. scaled comparison chart of pressure, gravity, discrete mass, discrete potential energy (pe) and cumulative pe curves for venus 4. discussion on venus the solar forced radiant heating of the upper troposphere at the zenith creates a process of pole-ward advection of heated air that feed the planet’s polar vortices (luz et al., 2011). figure 2 shows how the upper atmosphere of the lit hemisphere of venus intercepts the energy of the sunlight in a pattern of concentric rings of intensity centered around the zenith, the point at which the overhead sun provides the maximum flux that heats the atmosphere. when the sun heats the cold upper part of the venusian atmosphere it will distort the lapse rate slope to the warm side. that forces the lapse rate profile downward. that compression then steepens the lapse rate slope lower down which causes convection to accelerate as a negative compensation mechanism. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 32 published by scholink inc. as venus slowly turns from east to west, the locus of the solar zenith tracks along the equator towards the east creating a point of disturbance in the upper air. this forms a bow shockwave disruptor dividing the equatorial flow of the zonal circulating winds which are forced apart and made to track towards higher latitudes (figure 1). due to the conservation of angular momentum associated with the slow planetary rotation of venus, these winds travel faster than the ground surface below them and are called super-rotation winds (zasova et al., 2007). eventually these circulating winds reach the planet’s poles at a point on the rim of the lit hemisphere. here the illumination intensity of the low angle sun within 5 o of the terminator does not have sufficient power to heat the tropospheric air. at the poles of venus, the low power of the sunlight, combined with the angular momentum of the super-rotational winds creates a cyclonic vortex which drives the air down into the deep atmosphere below (ignatiev et al., 2009). figure 7. planetary rotation and the conservation of angular momentum this forced descent of the topside heated air, means that the compressible air undergoes adiabatic heating as it falls in the gravity field of venus. the descending mass flow within the polar vortex provides a hydrodynamic piston drive that causes the planet’s air to circulate vertically in a giant hemisphere encompassing hadley cell (figure 3). by this means the compressed air is heated as it falls and the apparent thermal limit set by insolation at the top of the atmosphere is easily surpassed (lacis & hansen, 1974). figure 3 shows the impact of upper atmosphere heating, the circulation system powered by the solar zenith constantly replenishes the forced descent vortex over both poles which heats the surfaces beneath. that energy then flows across the entire venusian surface so that it can reach temperatures much higher than predicted by the stefan-boltzmann (s-b) radiation equation. the greater the mass of the venus atmosphere the greater the system’s efficiency, and the more heat that will be delivered to the surface by the air descent at the poles. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 33 published by scholink inc. the piston-like hydrostatic circulation is fuelled by whatever energy is available from any source, but can never exceed the amount of energy required to balance the upward pressure gradient force with the downward force of gravity. the pattern of differing lapse rate slopes within the vertical plane is infinitely variable, but must always average out to the slope dictated by mass and gravity. 4.1 the utility of the daet climate model the key physical process that the daet climate model describes is that mobile compressible fluids circulating within a gravity field over and above the surface of a rotating terrestrial planet, will at the same time capture, store and transport energy in various guises. not all of these are thermal and so not all are subject to radiative loss. while energy can flow from cold to hot (e.g., the meteorological process of cooling rain falling onto the surface of a hot desert below), however heat being a directed dynamic process cannot flow from cold to hot (e.g., unconfined rivers of water cannot flow uphill). mass motion is a process that generates a system lag because it is inherently slower than radiative processes. convection is also a process that deals with albedo variations because convection just shifts to equalise these perturbations. there is still enough room for internal climate variability as the system lags somewhat in response to destabilising influences, but it always gets there quickly enough to retain the atmosphere in a dynamically stable state. the venus surface is at the temperature it is simply because that is the temperature needed to balance the mass of the atmospheric gases against gravity. it makes no difference what the source of that energy is. it is the same for stars in the cold of space and the gas planets far from the sun. convection always settles at a level that keeps the gases suspended against the downward force of gravity. until, in the case of stars, a fusion reaction starts whereupon convection adopts a new equilibrium. it is by this mechanism of circulating mass motion of a compressible gas acted on by a gravity field, within the context of a rotating spherical planet that surface thermal enhancement is created, and which it is proposed here to call the maxwell mass effect after the work of james clerk maxwell (maxwell, 1868). www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 34 published by scholink inc. 5. conclusion: the venus heating paradox explained in conclusion the matter of the high surface temperature of the planet venus, and the paradox of the dim surface sunlight not being able to create this 699 kelvin global average temperature will now be addressed. the process of deep atmospheric convection throughout the whole 62.2 km (100 mbar limit) of the venus troposphere means that sunlight heated air at the top of the atmosphere can and does deliver heat to the planet’s surface. instead of solar radiation, this process of energy delivery to the surface occurs by the mechanisms of full troposphere planetary rotation-forced mass-motion, the circulation of polar vortex descending air and heating by adiabatic auto compression. the warming at the surface of venus is from the mechanical process of convection, and any potential warming effect from downward radiation is neutralised by convective adjustments. instead, descending air heats both itself and the surface beneath via reconversion of potential energy (pe) to kinetic energy (ke). the atmosphere is held aloft by potential energy which is not thermal energy. heat cannot be amplified, but it can be stored in a non-kinetic form as potential energy so that it is not then sensed as temperature. potential energy is in effect a form of latent heat. this store of energy within mass is then returned again as temperature at a later time and critically at a lower elevation. so, as long as there is constant mass motion recycling to and fro between pe and ke as the air moves vertically within a gravity field, then the surface will receive kinetic energy from the descending air and be warmed. to maintain long term hydrostatic equilibrium the total energy retained at the surface must be a dynamic equilibrium that is just right to support the weight of atmospheric gases against the downward force of gravity. it makes no difference whether the source of the necessary energy is from the sun, the surface, volcanic outbreaks, atmospheric opacity, particulate aerosols or anything else. it is known that planetary atmospheres vary hugely in composition, and that the way the composition of an atmosphere is sorted into differing compositional layers will affect the vertical boundaries between those layers. thus, a tropopause can vary in height somewhat depending on the various compositionally induced stratifications within a planet’s atmosphere. however, if an atmosphere is to be retained by a planet, then the average lapse rate slope between surface and space must always net out to the slope specified by mass and gravity. convection always adjusts in order to balance energy into the system from space with energy out to space derived from the net combination of all energy transfer mechanisms between surface and atmosphere. if it were not so then the tiniest radiative imbalance would prevent the formation and retention of an atmosphere. it is known that atmospheres are ubiquitous and last for geological eons in the absence of catastrophe, so it must be that convection neutralises all “normal” radiative imbalances. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 35 published by scholink inc. however, the daet concept needs to apply to every scenario, whatever the density or opacity of an atmosphere the final outcome must be the same, and the cause will be a combination of heating of upper levels and heating of the surface with the proportions related to atmospheric opacity to radiation. it is a universal rule of meteorology that any temperature induced density variations in the vertical plane will lead to convective overturning in the entire depth of an atmosphere, with consequent heating of the surface. when the energy present in a mass aloft is converted from pe (not thermal) to ke (thermal) by forced descent then that solves the problem of the apparent radiative limit. radiation does not limit the mechanical transformation of energy between pe and ke in convection. climate theorists who have been fixated on radiation miss this point. potential energy is a form of latent heat. kinetic energy (motive heat) is the direct consequence of the conversion of potential energy during the descending phase of convective overturning. as the case of venus proves insolation does not need to reach the surface to provoke planetwide deep convection. it is sufficient if insolation beneath the solar zenith creates density differentials at any point within the mass of an atmosphere. convection can achieve that because radiative imbalances alter the lapse rate slope and the rate of convection changes in a negative response to this forcing (wilde, 2012). references ignatiev, n. i., titov, d. v., piccioni, g., drossart, p., markiewicz, w. j., cottini, v., roatsch, t., almeida, m., & manoel, n. (2009). altimetry of the venus cloud tops from the venus express observations. journal of geophysical research: planets, 114(e9). https://doi.org/10.1029/2008je003320 jenkins, j. m., steffes, p. g., hinson, d. p., twicken, j. d., & tyler, g. l. (1994). radio occultation studies of the venus atmosphere with the magellan spacecraft: 2. results from the october 1991 experiments. icarus, 110(1), 79-94. https://doi.org/10.1006/icar.1994.1108 justus, c. g., & braun, r. d. (2007). atmospheric environments for entry, descent, and landing (edl). nasa natural environments branch (ev13). lacis, a. a., & hansen, j. e. (1974). atmosphere of venus: implications of venera 8 sunlight measurements. science, 184(4140), 979-982. https://doi.org/10.1126/science.184.4140.979 limaye, s. s. (2010). measuring winds on venus and other planets. in 10th international wind workshop, tokyo (vol. 31). luz, d., berry, d. l., piccioni, g., drossart, p., politi, r., wilson, c. f., erard, s., & nuccilli, f. (2011). venus’s southern polar vortex reveals precessing circulation. science, 332(6029), 577-580. https://doi.org/10.1126/science.1201629 https://doi.org/10.1029/2008je003320 https://doi.org/10.1006/icar.1994.1108 https://doi.org/10.1126/science.184.4140.979 https://doi.org/10.1126/science.1201629 www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 36 published by scholink inc. maxwell, j. c. (2009). 1868. xxii. on the dynamical theory of gases. the london, edinburgh, and dublin philosophical magazine and journal of science, 35(236), 185-217. https://doi.org/10.1080/14786446808639963 mulholland, p., & wilde, s. p. r. (2020). inverse climate modelling study of the planet venus. international journal of atmospheric and oceanic sciences, 4(1), 20-35. https://doi.org/10.11648/j.ijaos.20200401.13 mulholland, p., & wilde, s. p. r. (2021). a modelled atmospheric pressure profile of venus: venus gravity profile 01mar21.xlsx research gate project update. retrieved from https://www.researchgate.net/publication/349838009_venus_gravity_profile_01mar21 singh, d. (2019). venus nightside surface temperature. scientific reports, 9(1), 1-5. https://doi.org/10.1038/s41598-018-38117-x wilde, s. p. r. (2012). the ignoring of adiabatic processes—big mistake. tallbloke’s talkshop. 14/12/2012 word press. williams, d. r. (2023). nasa venus fact sheet venus/earth comparison fact sheet nssdca. mail code 690.1, nasa goddard space flight center, greenbelt, md 20771. young, a. t. (1973). are the clouds of venus sulfuric acid? icarus, 18(4), 564-582. https://doi.org/10.1016/0019-1035(73)90059-6 zasova, l. v., ignatiev, n., khatuntsev, i., & linkin, v. (2007). structure of the venus atmosphere. planetary and space science, 55(12), 1712-1728. https://doi.org/10.1016/j.pss.2007.01.011 appendix the pressure profile calculation method: starting with the gas equation: p1.v1/t1 = p2 v2/t2 equation 1 where: p1 is the initial gas pressure measured in pascal. v1 is the initial gas volume measured in litres. t1 is the initial gas temperature measured in kelvin. p2 is the final gas pressure measured in pascal. v2 is the final gas volume measured in litres. t2 is the final gas temperature measured in kelvin. in the troposphere as height above the surface increases, air pressure and air temperature both decrease. in the open atmosphere the air pressure decrease is a function of air mass and gravity, while the temperature decrease, the lapse rate, is a measured known parameter (jenkins et al., fig. 4., 1994). this then leaves the change in volume with height as the one variable to be calculated. equation 1 can be rearranged to give volume in terms of pressure and temperature https://doi.org/10.1080/14786446808639963 https://doi.org/10.11648/j.ijaos.20200401.13 https://doi.org/10.1038/s41598-018-38117-x https://doi.org/10.1016/0019-1035(73)90059-6 https://doi.org/10.1016/j.pss.2007.01.011 www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 37 published by scholink inc. v2 = p1.v1.t2/t1 /p2 equation 2 the next issue to be resolved is to determine the rate of pressure reduction with height. in a column of air, the pressure is a function of the overlying mass, so if that the atmosphere is modelled as a stack of one metre cubes of air, then for each one metre rise in height the mass of the overlying column will be less, and so this mass reduction will cause a pressure reduction which can be calculated. pressure is a force; it is defined as the product of mass times acceleration. in the atmosphere the acceleration acting on the air parcel at rest in the column is the planet’s gravity at that level, and this can be determined by newton’s gravity law of spherical shells. the value of the surface gravity of a planet can be calculated by using the universal gravity equation, and knowing the planet’s mass and its average radius. but a standard measured quantity of gas is also required. to do this the process used by chemists to find the relationship between the mass in grams and the volume in litres (dm 3 ) at standard temperature and pressure (stp) for one mole of gas has been adopted here. at 273.15 kelvin (0 o c) and 1013.25 hpa (mbar) the volume is 22.414 litres (dm 3 ) and so for air with a molecular weight of 43.45 g/mol (standard venus atmospheric composition) the mass contained in molecular volume (22.414 dm 3 ) will be 43.45g. phase 1: building the pressure ladder for the venus atmosphere. step 1: from knowledge of the surface pressure of the venusian atmosphere and the value of the surface gravity of venus, compute the total atmospheric mass in a column bearing down on 1 square metre of the planet’s surface. using the equation of force f = m.a this equation can be restated as pressure/gravity = mass for venus the equation of state is: 9,321,900/8.87039 = 1,050,990.969 kg (1,051 tonnes/sq metre). step 2: compute the volume change for i mole of gas from stp at the earth’s surface to the ambient temperature and pressure conditions on the surface of venus. using the constant pressure volume temperature relationship of p1.v1/t1 = p2.v2/t2 this establishes the unknown v2 (the volume of 1 mole of gas at the surface of venus). v2 = p1.v1.t2/t1 /p2 v2 = 101,325 * 22.414 * 699 / 273.15/9,321,900 = 0.623 dm 3 (litres) step 3: compute the density of the unit mole of compressed gas at the surface of venus under ambient surface conditions. using the standard formula: density = molecular weight/volume surface density = 43.45 / 0.623 = 69.691 kg/m 3 . step 4: convert the gas density to discrete mass of gas per unit metre cube. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 38 published by scholink inc. discrete mass = 69.691 kg step 5: establish the mass of gas in the atmospheric column lying above this unit cube. mass bearing down = column mass minus unit mass mass bearing down at 1 metre elevation = 1,050,900.969 – 69.691 = 1,050,831.277 kg. there is now sufficient information to begin climbing the pressure ladder of the venus atmospheric profile at unit steps of 1 metre increment. phase 2: climbing the pressure ladder of the venus atmosphere. step 1: compute the new p2, the base pressure of the overlying column of gas. using the standard equation of force: f = m.a where m is the mass of the overlying column and a is the value of gravity at the surface of venus. p2 = 1,050,831.277 * 8.87039 = 9,321,282 pascal step 2: compute the new value of t2 one metre above the base surface temperature of venus using the relevant predictive tropospheric lapse rate equation in k/m and inputting the height value h where h is the full distance above the surface in metres. t2 = 699-7.967*h/1000= 698.9920 kelvin step 3: compute the new value of v2 at one metre elevation using the standard pressure volume temperature relationship v2 = p1.v1.t2/t1 /p2 v2 = 9,321,900 * 623.458 * 698.9920/699.0000 / 9,321,282 = 623.492 cm 3 n.b. the volume increase for v2 is due to the reduction in pressure p2 (which increases volume) dominating over the reduction in temperature t2 (which decreases volume) in the equation for each step up the ladder. step 4: compute the density of the new unit cube of gas. using the standard formula: density = molecular weight/volume new density = 43.45/623.492* 1,000 = 69.68758 kg/m 3 . step 5: convert the new gas density to discrete mass of gas per unit cube. discrete mass = 69.688 kg step 6: subtract the discrete unit cube mass from the column mass at this level to give the overlying column mass bearing down on this unit cube. overlying mass = current column mass minus unit mass bearing down mass = 1,050,831.277 – 69.688 = 1,050,761.590 kg step 7: use newton’s gravity law of spherical shells and set m2 to be the unit mass to compute the reduced value of planetary gravity at this new increment of 1 metre elevation. the required information to climb one step of the ladder and continue the calculation cycle is now known. the bearing down mass at the top of the unit cube defines the pressure at the base of the next unit cube above. step 8: return to step 1 and continue climbing the pressure ladder by 1 metre increments. energy and earth science vol. 5, no. 2, 2022 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 original paper opportunities and challenges of forest development in ethiopia kitessa gemechu beleta 1 1 ethiopian biodiversity institute, forest and range land plants biodiversity directorate, addis ababa, ethiopia received: february 12, 2022 accepted: february 24, 2022 online published: july 5, 2022 doi:10.22158/ees.v5n2p1 url: http://dx.doi.org/10.22158/ees.v5n2p1 abstract forests are essential for life on earth. they are not really simply the green cover; we require beautifying the earth. this research review aimed to overview the forest development opportunities and the challenges for forest development in ethiopia. published documents, reports from governments and non-governmental organizations on collective forest management were found via keyword searches in relevant literature data banks were used as data source materials. the global forest is declining at a rate of 13 million ha in each year. tropical forest decline is particularly severe in africa, brazil and indonesia. for example, africa has lost around 3.4 million ha per year between 2000 and 2010. ethiopia is thought to be losing 140,000 ha per year. deforestation, which is occurring at an alarming rate, is one of such problems and a key factor challenging forest development. deforestation, agricultural expansion and lack of strong coordinating forestry institutions are some of the challenges for forest development in ethiopia. the causes of deforestation and forest degradation are dynamics, complex, and vary from place to place. there are several reasons for the depletion of forest resources, the following are considered major: increases in population and consequent increases in the demand for agricultural land, settlements around forest areas, encroachments, forest fires, ranges of political, cultural, and socio-economic factors. technical advances in energy efficiency are critical for developing countries like ethiopia whose populations depend primarily on biomass fuels and reduce demand for fuelwood via the dissemination and usage of fuel-efficient stoves and/or alternative-fuel cooking and the collaboration of researchers, educators, and developmental extensions are needed to rehabilitate the degraded forest land. keywords deforestation, forest degradation, forests, forest coverage www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 2, 2022 2 published by scholink inc. 1. introduction deforestation and forest degradation are the biggest threats to forests worldwide. deforestation occurs when forests are converted into non-forest uses, such as agriculture and road construction. forest degradation occurs when forest ecosystems lose their capacity to provide important goods and services to people and nature. over half of the tropical forests have been destroyed since 1960s, and every second, more than one hectare of tropical forests is destroyed because of natural and man-made activities (jeffrey, 1991). forests display a range of structures and composition rising from the interplay between a wide range of altitudinal, climatic, soil environments, and different interactions between humans. forest is home for many living organisms; life in forests is governed by factors like air, water, and sunlight (epcc, 2015). there are a variety of plants available in most forests: herbs, shrubs, and trees depending upon the climate of the region. plants make their food by the process of photosynthesis and animals depend on plants and other animals for their food. plants also depend on animals for processes like pollination and seed dispersal. trees present in the forests hold the soil particles strongly with the roots and prevent them from erosion. it is not possible; to sum up, the importance of forests in just a few words (douglass and goodwin, 1980). 2. material and methods published documents, reports from governments and non-governmental organizations (ngos) on collective forest management were found via keyword searches in relevant literature data banks were used as data source materials. google, google scholar, research gate were used to undertake the literature search as a result, many articles, documents, book chapters and grey literatures such as conference papers, working papers, and reports in institutional series were obtained. 3. some definition and concept of forests based on management goals, land use, type of flora, composition, altitude, and other factors, the definition of the word “forest” differs from region to region and country to country. according to the fao (2001), a forest is defined as land with a tree crown cover (equivalent stocking level) of more than 10% and an area of more than 0.5 ha, with trees reaching a minimum height of 5 meters at maturity. according to fao (2006), forests have a minimum land area of 0.05-1 hectare, a tree crown covering more than 10-30% of the surface area, and a mature tree height of 2-5 meters. a forest, according to fao (2015), is defined as land with trees taller than 5 meters, a canopy cover of more than 10%, it excludes land that is primarily used for agriculture or urban development, included areas with young trees that have not yet reached a canopy cover of at least 10%; it also includes places that have become temporarily unhinged as a result of clear-cutting as part of a forest management technique or natural calamities, but are projected to rebound within 5 years. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 2, 2022 3 published by scholink inc. taking into account the wide range of definitions used around the world and the need for global efforts to mitigate the negative effects of deforestation and climate change, international organizations such as the fao and the unfccc developed some common and workable definitions based on certain parameters such as crown cover, area, and tree height as threshold values, and they are now widely used for assessing forest area, growing stock, and afforestation. 3.1 status of forest resources, opportunities, and challenges in global context according to (fao, 2015), the rate of global forest loss is decreasing; in the 1990s, the net loss of forest (natural and planted) was -0.18%, as indicated in (table 1). the net loss of forest was reduced to -0.08% between 2010 and 2015; the total area of planted forest has increased by over 110 million ha, covering approximately 7% of the world’s forest area. table1. global forest area change (1990-2015) year forest (000 ha) annual change (000 ha) annualized change references 1990 4,128,269 fao 2015 2000 4,055,602 -7,267 -0.18 2005 4,032,743 -4,572 -0.11 2010 4,015,673 -3,414 -0.08 2015 3,999,134 -3,308 -0.08 a global survey estimates that more than one-quarter of the household income in rural areas of developing countries stems from natural forests and other natural areas (angelsen et al., 2014). although, the net loss of forest was reduced, poor governance, over forest resource allows and illegal loggings have been continuing in many tropical countries. from illegally harvested timber, the global market losses estimated to be between usd 30-100 billion annually, and government revenue losses amount to an additional usd 5 billion per annum (wwf & iiasa, 2012). to address these challenges, multilateral and bilateral development partners, governments and the private sector have significantly increased support for the protection, restoration, and sustainable use of forests through various initiatives and programs over the last decade. the impacts of many programs are beginning to unfold and lessons are learned from moving from project to landscape level. many developing countries are in the process of formulating their national plans for mitigation actions. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 2, 2022 4 published by scholink inc. implementing redd+ and the expected ratification of the paris agreement has provided several new options and financing for countries to collaborate. also, high-level political discourse on developing deforestation-free supply chains offers a new window of opportunity for including the private sector and leveraging limited public finance. further, voluntary commitments in the context of forest landscape restoration (flr) should be support the operationalization of political objectives for the land-use sector and forests, including the investments in forest product value chains (nfsdp, 2018). 3.2 forest coverage of ethiopia forests are a dynamic ecosystem consisting primarily of trees that protect the earth and support a variety of life forms (epcc, 2015). forests have a variety of species composition, structure, and physiognomy due to environmental factors such as climate, soil types, topography, and elevation (bubb et al., 2004). in ethiopia, there is a scarcity of consistent and trustworthy data on forest resource coverage, standing stock, growth rate, production, and productivity. estimates from other sources varied significantly; this is due to in part to the many definitions of forest used. forest resources in ethiopia cover over 17.35 million ha (15.7% of the country’s land area), comprising bamboo, plantations, dense woodland, natural forests, and managed forests. the majority of the country’s natural forests are found in the south-western and south-eastern regions (mefcc, 2018). oromia, gambella, snnpr, amhara, and benishangul regional states have more natural forest resources respectively. oromia, snnpr, and amhara regional states have over 93.5% of the country’s total plantation resources (mefcc, 2018). table 2. estimates of area cover of various forest resources in ethiopia forest types area (ha) references bamboo 519,124 mefcc, 2018 dense woodland 10,739,286 natural forest 5,266,419 plantation 827,613 total 17,352,443 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 2, 2022 5 published by scholink inc. figure 1. distribution of the forest resources of ethiopia source: ema (2013). 3.3 opportunities for forest development in ethiopia 3.3.1 forest policies, institutions, and governance the ethiopian government has signed several of international conventions, such as: convention to combat desertification (ccd), the convention on climate change (ccc), the convention on biodiversity (cbd), the millennium development goal (mdg), the establishment of oromia and amhara forest enterprises, gtp, and green economy targets, all have provided opportunities to develop degraded forest land areas. 3.3.2 participatory forest management (pfm) the pfm program covers six forest priority areas in ethiopia those are, chilimo, bonga, borana, belete gera, adaba-dodola, sos sahel. sustainable land management (slm), agroforestry, priority high forests, national parks, and sacred site forests are all examples of community-based forest management techniques. trees planted around homesteads have a criticalroles for humans, as well as for animals. example, trees planted near homesteads could give additional food sources as well as cash income for the communities (tadesse, 2012). 3.3.3 reforestation/afforestation programs and agroecology reforestation is the direct human-induced conversion of non-forested land to forested land through planting, seeding, and/or the human-induced enhancement of natural seed sources. ethiopia has been implementing significant tree-planting programs as part of their millennium celebrations since 2007. according to certain local sources, ethiopia’s four regions, i.e., oromia, snnp, amhara, and tigray regional states planted a total of about 2.21 billion seedlings in 2009 (tadesse, 2012). on a nationwide scale, more than 5.6 billion seedlings are expected to be planted in 2010. since ethiopia is located in the tropics, there is an access of rainfall and high temperatures as a result, it is suitable for seedling growth. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 2, 2022 6 published by scholink inc. figure 2. planting forest trees as a green legacy 4. challenges of forest development in ethiopia 4.1 deforestation deforestation is the conversion of forest to another land use or the long-term reduction of tree canopy cover below the 10% threshold or deforestation implies the long-term (>10 years) or permanent loss of forest cover (tejaswi, 2007). natural resource depletion is one of the most serious concerns affecting humanity in all countries. ethiopia’s forest resources, have been steadily declining over time (tesfaye et al., 2017). since 1960, over half of the tropical forests have been destroyed; because of, livestock, insects, diseases, forest fires, and other human-linked activities. according to wbispp (2004), the first national inventory statistics on the forest resources indicated that in ethiopia there was a total of 59.7 million ha woody vegetation but, deforestation, which is occurring at an alarming rate, is a key factor challenging forest development. over 15 million ha of tropical forest was deforested at an annual rate of 0.8% over the globe in 1980 to 1990. africa recorded an annual loss of about 3.4 million ha from 2000 to 2010 (badege, 2001). it is estimated that ethiopia has lost 140,000 ha/year. ethiopia is facing rapid deforestation and degradation of land resources. the current rate of deforestation is estimated to be 160,000 to 200,000 ha per year (badege, 2001). forest and woodland cover change in ethiopia indicate that the average annual rate of deforestation is greater than 0.25% (hansen et al., 2010). 4.1.1 drivers of deforestation there are two types of drivers: direct and indirect drivers. direct deforestation are an expansion of smallholder traditional agriculture, wood extraction, forest product collection and forest fires whereas, population growth, developmental activities, a range of political, cultural, weak governance, lack of law enforcement, land less ness, unclear allocation of rights, rural poverty, lack of investment and financial resources, migration, and civil conflicts are some of the indirect drivers of deforestations (melaku et al., 2015). according to abera and belachew (2011), the cultivated area has increased from 9.44 million ha in 2001 to 15.4 million ha in 2009 in ethiopia, example, 1850 ha/year of boswellia woodland is converted into agricultural land (atkilit, 2011). www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 2, 2022 7 published by scholink inc. 4.2 lack of strong coordinating forestry institution the institutional (developmental extension, researches, and educations) arrangements have been unstable structuring. lack of stability in the organizational structure is often cited as one of the major bottlenecks for the lack of coordinated, effective, and long-term management and development successes in ethiopian forestry (demel et al., 2010; mulugeta & tadesse, 2010). lack of strong coordinating forest institution leads to poor coordination, monitoring, low resources allocations (manpower, budget, and logistic), poor inter-sectoral coordination, low policy implementation and low evaluation of forest development initiatives (tadesse, 2010). 5. conclusion forests are essential for life on earth. they are not really simply the green cover we require to beautify the earth. ethiopia’s agroecology encourages the restoration of degraded forests. that is to say, because ethiopia is located in the tropics, it has access to significant rainfall and high temperatures, both of which promote seedling growth. direct deforestation drivers in ethiopia are an expansion of smallholder traditional agriculture following population growth in forest areas, expansion of enormous-scale development activities, population growth, wood extraction, and other forest product collection and forest fires. underlying drivers include a range of political, cultural, and socio-economic factors, including unsound policies, weak governance and lack of law enforcement, landlessness and unclear allocation of rights, rural poverty, lack of investment and financial resources, migration, and civil conflict. deforestation, agricultural expansion and lack of strong coordinating forest institutions are some of the challenges for forest development in ethiopia. the country needs to invest in forestry (research, extension, and education) before the problems get out of hand. the collaboration of researchers, education, development/extensions, and the stakeholders are needed to rehabilitate the degraded forest resources in ethiopia. acknowledgments this review article contains information collected from various published resources; thus, i would like to acknowledge all authors of the references used in this review. www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 2, 2022 8 published by scholink inc. references abayneh et al. (2010). tree-planting, millennium development goal. abera, y., & belachew, t. (2011). effects of landuse on soil organic carbon and nitrogen in soils of bale, southeastern ethiopia. tropical and subtropical agroecosystems, 14(1), 229-235. ameha, a., larsen, h. o., & lemenih, m. (2014). participatory forest management in ethiopia: learning from pilot projects. environmental management, 53, 838-854. https://doi.org/10.1007/s00267-014-0243-9 angelsen et al. (2014). environmental income and rural livelihoods: a global-comparative analysis. world development, 64, s12-s28. https://doi.org/10.1016/j.worlddev.2014.03.006 arevalo. (2016). unclear allocation of rights, rural poverty, lack of investment and financial resources, migration and civil conflict. badege, b. (2001). deforestation and land degradation on the ethiopian highlands: a strategy for physical recovery. böhmer, h. (2011). vulnerability of tropical montane rain forest ecosystems due to climate change. in coping with global environmental change, disasters and security (pp. 789-802). springer, berlin, heidelberg. https://doi.org/10.1007/978-3-642-17776-7_46 bubb, p., miles, l., & sayer, j. (2004). cloud forest agenda. demel et al. (2010). historical development of forest policy in ethiopia. douglass, j. e., & goodwin, o. c. (1980). runoff and soil erosion from forest site preparation practices. in proceedings of the us forestry and water quality: what course in the 80’s (pp. 19-20). ethiopian biodiversity inistitute (ebi). (2020). addis abeba. ethiopian forestry action program (efap). (1994). addis abeba. ethiopian mapping agency (ema). (2013). addis abeba. ethiopian national forest sector development program (enfsdp). (2018). synthesis report (vol. iii). ethiopian panel on climate change. (2015). first assessment report, working group i physical science basis. published by the ethiopian academy of sciences. food and agriculture organization (fao). (2001). state of the world’s forests. italy, rome. retrieved from https://ftp.fao.org/docrep/fao/003/y0900e food and agriculture organization (fao). (2006). world reference base for soil resources. a framework for international classification, correlation and communication. italy, rome. food and agriculture organization (fao). (2010). global forest resources assessment country report ethiopia (p. 43). food and agriculture organization of the united nations, rome. food and agriculture organization (fao). (2015). global forest resources assessment (fra). retrieved from https://www.fao.org/forestry/fra https://doi.org/10.1007/s00267-014-0243-9 https://doi.org/10.1016/j.worlddev.2014.03.006 https://doi.org/10.1007/978-3-642-17776-7_46 www.scholink.org/ojs/index.php/ees energy and earth science vol. 5, no. 2, 2022 9 published by scholink inc. forests and wood products. (2012). wwf & iiasa. in wwf living forests report: chapter 4. retrieved from http://wwf.panda.org/about_our_earth/deforestation/forest_publications_news_and_reports/living_ forests_report/ friis, i. b. (1992). forests and forest trees of northeast tropical africa: their natural habitats and distribution patterns in ethiopia, djibouti and somalia. hmso. hansen et al. (2010). woodland cover change in ethiopia. hoare, a. (2015). tackling illegal logging and the related trade: what progress and where next. in chatham house report. labin, & geist. (2006). drivers of change often comprise more fold factors and drivers such as interaction of economic, institutional, technological, cultural and demographic variables where economic factors are prominents. melaku et al. (2015). population growth, wood extraction and other forest products collection and forest fires. agrofor.syst., 80(2), 173-184. national forest sector development program. (2018). addis abeba. sayer, j. a., & whitmore, t. c. (1991). tropical moist forests: destruction and species extinction. biological conservation, 55(2), 199-213. solomon, a., & demel, t. (2017). perceptions and attitudes of local people towards participatory forest management in tarmaber district of north shewa administrative zone, ethiopia: the case of wof-washa forests. ecological processes, 6(17). https://doi.org/10.1186/s13717-017-0084-6 tadesse, w. (2012). the status of forestry development in ethiopia: challenges and opportunities. national dialog on sustainable agricultural intensification in ethiopia and its role on the climate resilient green economy initiative in ethiopia. tejaswi, 2007. tesfaye, y. (2011). participatory forest management for sustainable livelihoods in the bale mountains, southern ethiopia (phd dissertation). swedish university of agricultural sciences, uppsala. wbispp. (2004). woody biomass inventory and strategic planning project forest resource accounts for ethiopia. wwf, i. (2012). living forests report. gland, switzerland. zikargae, m. h. (2018). analysis of environmental communication and its implication for sustainable development in ethiopia. science of the total environment, 634, 1593-1600. https://doi.org/10.1016/j.scitotenv.2018.04.050 https://doi.org/10.1186/s13717-017-0084-6 https://doi.org/10.1016/j.scitotenv.2018.04.050 energy and earth science vol. 6, no. 3, 2023 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 original paper an assessment to human perception to the origin of coronavirus by the impact of climate change and preventative management of pandemic coronavirus covid-19 akanda md. raihan gafur 1* , a s m mahmudul hasan rifat 2 & mst. nazneen sultana 3 1 department of water resources development, bangladesh university of engineering and technology, dhaka, bangladesh 2 department of environmental sciences, jahangirnagar university, dhaka, bangladesh 3 department of economics, national university, dhaka, bangladesh * akanda md. raihan gafur, department of water resources development, bangladesh university of engineering and technology, dhaka, bangladesh received: june 26, 2023 accepted: july 24, 2023 online published: august 12, 2023 doi:10.22158/ees.v6n3p1 url: http://dx.doi.org/10.22158/ees.v6n3p1 abstract on 12 january 2020, the who confirmed that a novel coronavirus was the cause of a respiratory illness in a cluster of people in wuhan city, china. the aims of the study to assess the human perception to the origin of coronavirus with relation to nature and find out preventative management about coronavirus. primary data was collected for analyzing some factors regarding the coronavirus microorganism formed by the impact of climate change. primary data was collected through an online questionnaire survey. an online questionnaire survey is used for human perception for taking public opinion about the origin of coronavirus and preventative management which are conducted in bangladesh. spss software is used for linear regression analysis and correlation with some variables. a total of three variables were considered in the model estimation of which are dependent variables coronavirus microorganism formed by the impact of climate change and independent variables such as coronavirus microorganism formed by the impact of environmental pollution, coronavirus microorganism formed by the impact of global heat and coronavirus microorganism originated by the sources of the impact of ice melting polar region. from the analysis, it is found that the coronavirus microorganism formed by the impact of climate change that makes a unique and statistically significant contribution to the prediction. among 200 respondents, about 70% of peoples said “maybe” www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 2 published by scholink inc. coronavirus microorganism formed by the impact of climate change, and it’s some factor. it is also found from the correlation analysis that the epidemic effects of covid-19 will high on bangladesh, if immigrant persons come, if curfew doesn’t issue, if peoples are not conscious, if peoples are not properly using mask and hand gloves, if they are not maintaining social distance and lock down rules. in the finding that, in the polar region, there are many ice stacks where thousands of years ago, the animals are dead but the virus and bacteria are in a state of sleep. as the heat increases, all glaciers and permafrost start to melt in the polar region. as a result, many types of viruses, bacteria are starting to live. these viruses including coronavirus will be mixed with different environmental elements such as water, biodiversity. this will easily affect biodiversity and other animals including humans. above all climate change may play a significant role in the transmission of many infectious diseases including coronavirus. community responses are important for outbreak management during the early phase of major preventive options. keywords covid-19, who, climate changes, preventative, epidemic, community 1. introduction on 31 december 2019, china reported to the who cases of pneumonia with unknown causes. on 12 january 2020, the world health organization (who) confirmed that a novel coronavirus was the cause of a respiratory illness in a cluster of people in wuhan city, hubei province, china (reynolds, matt, 2020) since december 2019 as “2019-ncov”, which was renamed by the international committee on taxonomy of viruses as “sars-cov-2” on 11 february 2020. in parallel, the who formally named the disease caused by sars-cov-2 as “covid-19”, short for coronavirus disease 2019. back in late december 2019, a cluster of 27 pneumonia cases associated with sars-cov-2 with a common link to the huanan seafood wholesale market was reported (kwok on kin et al.). bangladesh faces significant challenges in combating covid-19 as it is a densely populated country and also houses a million stateless rohingya refugees in sprawling refugee camps that are conducive to the spread of epidemics. it also has significant migrant populations living in italy, a covid-affected country (iedcr, 2020). the 2019-2020 coronavirus pandemic was confirmed to have spread to bangladesh on march 2020. the first three known cases were reported on 7 march 2020 by the country’s epidemiology institute iedcr. infections stayed low till the end of march but saw a steep rise in april (iedcr, 2020). climate change is identified as the most pressing concern for human health in the 21st century and climate change mitigation as the greatest public health opportunity of this generation. epidemics, just like weather and climate can threaten human health and social stability. since the millennium, the emergence of the coronavirus in 2003, the novel avian influenza (h1n1) in 2009, the ebola virus in west africa (2014-2016) and the zika virus in the americas (2015), amongst others, have www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 3 published by scholink inc. demonstrated the speed at which infectious diseases can spread with devastating effect (bloom, black & rappuoli, 2017). as the planet warms and the ice thaws, scientists warn we could see the re-emergence of ancient pathogens currently unknown to science. these viruses, which have laid dormant and locked away in glaciers and permafrost—permanently frozen soil—for hundreds if not thousands of years, could “wake up”, researchers have said. climate change causes ancient viruses to re-emerge. when ice melts then it will release glacial microbes and viruses that have been trapped and preserved for tens to hundreds of thousands of years. this melt could destroy microbial “archives” that may help us understand the earth’s climate regimes in the past. however, in a worst-case scenario, this ice melt could release pathogens into the environment. it is now well understood that the impacts of climate change on global health and development are manifold. they result from changes in the extent and distribution of global warming of the atmosphere and oceans. climate change is leading us to mass extinction. now, the consequences of global warming are terrible (costello et al., 2009). in bangladesh, adopted strategies include: border screening (measuring body temperature, imposing a health declaration form system), imposing a 14-day mandatory quarantine period on all individuals entering bangladesh from the mainland, social-distancing (border shutdown, reducing cross-border commuting services, deferring class resumption for schools governed by the education bureau, home-office arrangement for civil servants, suspension of public services from the leisure and cultural services department) and extending the enhanced laboratory surveillance program to adult patients with fever and mild respiratory symptoms presenting at accident and emergency departments or general out-patient clinics under the public sector. the host’s behaviors are important for outbreak management, particularly during the early phase when no treatment or vaccination is available and non-pharmaceutical interventions (npis) are the only options. the efficacy of npis depends on the host’s degree of engagement and compliance in precautionary behaviors, such as wearing masks, hand hygiene, and self-isolation. whether individuals voluntarily engage in precautionary behaviors depends on their risk perception of the current health threat. human risk perception is the main theme in common health behavior theories (kwok on kin et al.). this study aims to assess the human perception to the origin of coronavirus with relation to nature and coronavirus microorganism formed by the impact of climate change and it’s some factor. considering the rapid development of the epidemic during the survey period and the potential variability in the adoption of preventive measures among hosts, this study also explores preventative management about coronavirus covid-19 and behavioral responses of the general community during the early phase of the covid-19 epidemic. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 4 published by scholink inc. 2. objectives and methodology of the study this paper aimed to assess the human perception to the origin of coronavirus with relation to nature and find out preventative management about coronavirus covid-19. an online questionnaire survey was conducted in bangladesh within 15 th march to 15 th april, 2020 after the confirmed covid-19 case was reported in the country’s epidemiology institute iedcr. to avoid duplicated responses from the same respondent, the survey could only be taken once from the same electronic device. primary data was collected for analyzing some factors regarding the coronavirus microorganism formed by the impact of climate change. primary data was collected through an online questionnaire survey. an online questionnaire survey is used for demographic information (sex, age, and education level), human perception about covid-19 for taking opinion for coronavirus microorganism formed by the impact of climate change and preventative management about covid-19. microsoft excel software is used for some simple statistical data analysis and spss software is used for linear regression analysis and correlation with some variables. a total of three variables were considered in the model estimation of which are dependent variables coronavirus microorganism formed by the impact of climate change and independent variables such as coronavirus microorganism formed by the impact of environmental pollution, coronavirus microorganism formed by the impact of global heat and coronavirus microorganism originated by the sources of the impact of ice melting polar region. besides some variable correlation with epidemic effects of covid-19 will high on bangladesh, if immigrant persons come, if curfew doesn’t issue, if peoples are unconscious, if peoples are not properly using the mask and hand gloves, if they are not maintaining social distance and lockdown rules. there are also some guidelines about preventive management of covid-19. 3. literature review in 2003, the chinese population was infected with a virus causing severe acute respiratory syndrome (sars) in guangdong province. the virus was confirmed as a member of the betacoronavirus subgroup and was named sars-cov (peiris, guan, yuen, 2003; pyrc, berkhout, van der hoek, 2007). a decade later in 2012, a couple of saudi arabian nationals were diagnosed to be infected with another coronavirus. the detected virus was confirmed as a member of coronaviruses and named as the middle east respiratory syndrome coronavirus (mers-cov) mers-cov is a member beta-coronavirus subgroup and phylogenetically diverse from other human-cov (rahman & sarkar, 2019). recently, by the end of 2019, who was informed by the chinese government about several cases of pneumonia with unfamiliar etiology. the outbreak was initiated from the hunan seafood market in wuhan city of china and rapidly infected more than 50 peoples. the coronavirus disease (covid-19) has been identified as the cause of an outbreak of respiratory illness in wuhan, hubei province, china beginning in december 2019. the world health organization has declared it a public health emergency of international concern (cui, li & shi, 2019; lai, shih, ko, tang & hsueh, 2020). www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 5 published by scholink inc. sars-cov-2 is a member of the coronavirus family, named for the crown-like appearance of spikes on the virus surface. coronaviruses belong to the coronaviridae family in the nidovirales order. like mers-cov and sars-cov-1, sars-cov-2 is a beta coronavirus and is likely associated with an animal reservoir (e.g., bats). coronaviruses are minute in size (65-125 nm in diameter) and contain a single-stranded rna as a nucleic material, size ranging from 26 to 32kbs in length(zhong, zheng, li, poon, xie, chan et al., 2003). all coronaviruses contain specific genes in orf1 downstream regions that encode proteins for viral replication, nucleocapsid, and spikes formation (van boheemen, de graaf, lauber, bestebroer, raj, zaki et al., 2012). the glycoprotein spikes on the outer surface of coronaviruses are responsible for the attachment and entry of the virus to the host. the receptor-binding domain (rbd) is loosely attached among virus, therefore, the virus may infect multiple hosts (raj, mou, smits, dekkers, müller, dijkman et al., 2013; perlman & netland, 2009). emerging infectious diseases pose a threat to public health, animal agriculture, and wildlife conservation (daszak et al., 2000). the majority of emerging infectious diseases in humans are zoonosis, and two-thirds of these originate in wildlife (jones et al., 2008). bats are implicated in the emergence of many zoonotic diseases, including the coronaviruses (covs) responsible for deadly outbreaks of the severe acute respiratory syndrome (sars) in 2002-2003, and middle east respiratory syndrome (mers) which first emerged in 2012 (baldwin, 2015). emerging viral infections in both humans and animals have been reported with increased frequency in recent years. recent advances have been made in our knowledge of some of these, including severe acute respiratory syndrome-associated coronavirus, influenza a virus, human metapneumovirus, west nile virus, and ebola virus. research efforts to mitigate their effects have concentrated on improved surveillance and diagnostic capabilities, as well as on the development of vaccines and antiviral agents. more attention needs to be given to the identification of the underlying causes for the emergence of infectious diseases, which are often related to anthropogenic social and environmental changes. addressing these factors might help to decrease the rate of emergence of infectious diseases and allow the transition to a more sustainable society (kuiken, fouchier, rimmelzwaan & osterhaus, 2003). climate change is identified as the most pressing concern for human health in the 21st century. climate interacts with health through a wide variety of direct and indirect mechanisms (marmot, 2005). the impacts of weather and climate events, such as droughts, floods, storms, heat waves, sea-level rise, and generalized warming, threaten the health of vulnerable populations around the world. many infectious diseases are climate-sensitive; climate acting as an important driver of spatial and seasonal patterns of infections, year-to-year variations in incidence (including epidemics), and longer-term shifts in populations at risk (kelly-hope & thomson, 2008). increasingly those responsible for the development of disease control strategies have identified. climate may play a significant role in the transmission of many infectious diseases (thomson et al., 2017). www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 6 published by scholink inc. according to the us centers for disease control and prevention (cdc), there is no specific recommended antiviral therapy for covid-19 (who, 2020). active surveillance for new cases and close monitoring of their contacts are necessary to control the spread of covid-19. to improve detection efficiency, front-line clinics, apart from local centers for disease control and prevention should be armed with validated point-of-care diagnostic kits. education campaigns should be launched to promote precautions for travelers, including frequent hand-washing, cough etiquette, and use of personal protection equipment (e.g., masks) when visiting public places. also, the general public should be motivated to report fever and other risk factors for viral infection, including travel history to affected area and close contacts with confirmed or suspected cases (khan, muhammad, khayal, ahmed & rahman, 2020). 4. data analysis result and discussion 4.1 respondent characteristics complete data from 200 respondents were analyzed. respondents were asked about their demographics information (including sex, age, and education). many of the respondents are male (69%), of young age (25-54 years) (80%), education level honors (68%). most of the respondents were asked about coronavirus microorganism formed by the impact of climate change and its some factor. it is also asked about the epidemic effects of covid-19 and some preventative measures. 4.2 human perception of coronavirus microorganism related to nature respondents were asked about coronavirus microorganism related to nature. coronavirus microorganism formed by the impact of climate change and its some factor. these factors are coronavirus microorganism formed by the impact of environmental pollution, coronavirus microorganism formed by the impact of global heat, and coronavirus microorganism originated by the sources of the impact of ice melting polar region. figure 1. coronavirus curse of nature globally source: author preparation, 2020. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 7 published by scholink inc. among 200 respondents, about 64% of peoples said that coronavirus is a curse of nature. as the form of nature is changing day by day. there needs to be given more attention to the identification of the underlying causes for the emergence of infectious diseases, which are often related to anthropogenic social and environmental changes. figure 2. coronavirus microorganism formed by climate change source: author preparation, 2020. according to human perception, about 70% of peoples said “maybe” coronavirus microorganism formed by the impact of climate change, and it’s some factor. global warming increasing day by day on the earth which causes massive environmental change. many infectious diseases are climate-sensitive; climate change acting as an important role to exposed many viruses. 4.3 result and interpretation of statistical analysis spss software is used for linear regression analysis and correlation with some variables. a total of three variables were considered in the model estimation of which are dependent variables coronavirus microorganism formed by the impact of climate change and independent variables such as coronavirus microorganism formed by the impact of environmental pollution, coronavirus microorganism formed by the impact of global heat and coronavirus microorganism originated by the sources of the impact of ice melting polar region. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 8 published by scholink inc. table1. results from the regression analysis model summery model r r square adjusted r square std. error of the estimate linear regression .534 a .285 .255 .566 anova model type model sum of squares df mean square f sig. linear regression regression 12.130 4 3.032 9.467 .000 b residual 30.430 95 .320 total 42.560 99 co-efficient dependent variable model variables coefficient std. error of the estimate t sig. ln (v) constant .741 .253 2.926 .001 coronavirus microorganism formed by the impact of environment pollution -.152 .118 -1.289 .201 coronavirus microorganism formed by the impact of global heat .453 .116 3.911 .000 coronavirus microorganism originated from the sources of the impact of ice melting polar region .198 .118 1.681 .004 note. dependent variable: coronavirus microorganism formed by the impact of climate change. source: author preparation, 2020. the coefficient of determination r 2 is calculated by linear regression of spss software. rafiq explains that “the r 2 measures the proportion of the variation in the dependent variable explained by the independent variables” (rafiq, 2012, p. 67). a higher r 2 would suggest that the calculated regression equation line fits closer to the data points (azyyati et al., 2007). the r 2 for the regression equation of the study is 28.5% (table 1 (model summary)). this result means that the model explains 28.5% of the variance in coronavirus microorganism formed by the impact of climate change. the value of r 2 is low which means that there may be other possible variables that may influence the coronavirus microorganism formed by the impact of climate change which is not included in the regression analysis. another possible factor is people’s perception of answering any decision which changes from time to time. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 9 published by scholink inc. anova table can be used to evaluate the statistical significance of the result. table 1 indicates that f value is 9.467 where significance level is 0.000. the computed f value is given as which exceeds the critical value of f which is 1.94 where significance level is 0.05. it can be concluded from f value that at least one of the regression coefficients are not equal to zero. from table 1, the beta values can be observed as a coefficient of each independent variable. coronavirus microorganism formed by the impact of global heat, coronavirus microorganism originated by the sources of the impact of ice melting polar region makes the stronger unique contribution to explain the dependent variable coronavirus microorganism formed by the impact of climate change for their larger beta coefficients (0.453 for coronavirus microorganism formed by the impact of global heat, 0.198 for coronavirus microorganism originated by the sources of the impact of ice melting polar region). the beta values for other variables are very low, indicating there less contribution to the model. the column labeled as sig. in table 1 (coefficient) shows whether the variable is making a statistically significant unique contribution to the model or not. if the sig. value is less than 0.05, the variable is making a significant unique contribution to the prediction of the dependent variable. and if the value is greater than 0.05, it can be said that that variable is not making a significant unique contribution to the prediction of the dependent variable. from the sig. value of this table 1 it can be seen that only coronavirus microorganism formed by the impact of global heat and coronavirus microorganism originated by the sources of the impact of ice melting polar region make a unique and statistically significant contribution to the prediction of coronavirus microorganism formed by the impact of climate change because in this case the sig. value is less than 0.05. other variables make no unique and statistically significant contribution to the prediction of the coronavirus microorganism formed by the impact of climate change because of their sig. value which is more than 0.05. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 10 published by scholink inc. table 2. correlation between coronavirus microorganism formed by the impact of climate change and coronavirus microorganisms formed by the impact of environmental pollution table 3. correlation between coronavirus microorganism formed by the impact of climate change and coronavirus microorganisms formed by the impact of global heat coronavirus microorganism formed by the impact of climate change coronavirus microorganism formed by the impact of global heat coronavirus microorganism formed by the impact of climate change pearson correlation 1 .507 ** sig. (2-tailed) .000 n 200 200 coronavirus microorganism formed by the impact of global heat pearson correlation .507 ** 1 sig. (2-tailed) .000 n 200 200 coronavirus microorganism formed by the impact of climate change coronavirus microorganism formed by the impact of environment pollution coronavirus microorganism formed by the impact of climate change pearson correlation 1 .302 ** sig. (2-tailed) .000 n 200 200 coronavirus microorganism formed by the impact of environment pollution pearson correlation .302 ** 1 sig. (2-tailed) .000 n 200 200 www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 11 published by scholink inc. table 4. correlation between coronavirus microorganism formed by the impact of climate change and coronavirus microorganism originated from the sources of the impact of the ice melting polar region coronavirus microorganism formed by the impact of climate change coronavirus microorganism originated from the sources of the impact of ice melting polar region coronavirus microorganism formed by the impact of climate change pearson correlation 1 .386 ** sig. (2-tailed) .000 n 200 200 coronavirus microorganism originated from the sources of the impact of ice melting polar region pearson correlation .386 ** 1 sig. (2-tailed) .000 n 200 200 source: author preparation, 2020. it is apparent from table 2, 3 and 4 that coronavirus microorganism formed by the impact of environmental pollution, coronavirus microorganism formed by the impact of global heat and coronavirus microorganism originated by the sources of the impact of ice melting polar region of 200 respondents who have coronavirus microorganism formed by the impact of climate change directly is positively correlated with coronavirus microorganism formed by the impact of climate change and. sig. the value in the table shows whether the variable is making a statistically significant unique contribution to the other factor or not. if the sig. value is less than 0.05, the variable is making a significant unique contribution to the prediction of other variables. and if the value is greater than 0.05, it can be said that that variable is not making a significant unique contribution to the prediction of other variables. from the sig. value of these tables it can be seen coronavirus microorganism formed by the impact of environmental pollution, coronavirus microorganism formed by the impact of global heat and coronavirus microorganism originated by the sources of the impact of ice melting polar region that make a unique and statistically significant contribution to the prediction of the coronavirus microorganism formed by the impact of climate change because in case the sig. value is less than 0.05. 4.4 preventative management about covid-19 in the context of bangladesh respondents think that epidemic effects of covid-19 will high on bangladesh, if immigrant persons come, if curfew doesn’t issue, if peoples are not conscious, if peoples are not properly using the mask and hand gloves, if ppe and masks distributed properly among medical staff, if they are not maintaining social distance and lockdown rules. respondents were asked whether they performed precautionary measures and what their perceived efficacies of those measures are. three types of www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 12 published by scholink inc. precautionary measures were considered: hygienic practices, social distancing, and travel avoidance. enhanced personal hygiene practices (including wearing masks, cleaning hands and better coughing and sneezing etiquette) and avoid traveling to coronavirus affected country. for social-distancing measures were considered useful in preventing covid-19. the table shows the correlation analysis results for the epidemic effects of covid-19 will high in bangladesh. figure 3. proper management about covid-19 source: author preparation, 2020. it is apparent from figures that about 60% of respondents think that there was not any proper management taken by the government of bangladesh about covid-19. it isn’t the right decision to let immigrant persons come to bangladesh and curfew doesn’t issue due to this reason the epidemic effect of covid-19 will high on bangladesh. about 40% respondents said that bangladesh government take a necessary step about covid-19 adopted strategies include: border screening measuring body temperature, imposing a 14-day mandatory quarantine period on all individuals entering bangladesh from the mainland, social-distancing (lockdown, border shutdown, closing religious place, closing all educational institution, home-office arrangement for civil servants, suspension of public services from the leisure and cultural services department). www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 13 published by scholink inc. figure 4. ppe and masks distributed properly among medical staff source: author preparation, 2020. it is apparent from figures that about 80% of respondents think that there was not any proper distribution of ppe and masks among the medical staff. if there was no proper distribution of ppe and masks among the medical staff, epidemic effects of covid-19 will high in bangladesh. medical staffs are in direct contact with patients. so they are at high risk in covid-19. if they get affected, then community transmission will be high. so ppe and masks should be distributed properly among the medical staff and the government should take proper steps for it. table 5. correlations between the epidemic effect of covid-19 will high on bangladesh and if immigrant persons come epidemic effect of covid-19 will high on bangladesh if immigrant persons come epidemic effect of covid-19 will high on bangladesh pearson correlation 1 .230 ** sig. (2-tailed) .001 n 200 200 if immigrant persons come pearson correlation .230 ** 1 sig. (2-tailed) .001 n 200 200 source: author preparation, 2020. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 14 published by scholink inc. a pearson product-moment correlation coefficient was computed to assess the relationship between the epidemic effect of covid-19 will high on bangladesh and if immigrant persons come. there was a positive correlation between the two variables that make a unique and statistically significant contribution to the prediction. if the number of immigrant persons comes to bangladesh increases, the epidemic effect of covid-19 will also increase in bangladesh. among 200 respondents, about 84% of peoples said that it isn’t the right decision to let immigrant persons come to bangladesh and due to this reason the epidemic effect of covid-19 will high in bangladesh. table 6. correlations between epidemic effect of covid-19 will high on bangladesh and if curfew doesn’t issue for covid-19 epidemic effect of covid-19 will high on bangladesh if curfew doesn’t issue for covid-19 epidemic effect of covid-19 will high on bangladesh pearson correlation 1 .662 ** sig. (2-tailed) 0 n 200 200 if curfew doesn’t issue for covid-19 pearson correlation .662 ** 1 sig. (2-tailed) 0 n 200 200 source: author preparation, 2020. it is apparent from the table there was a positive correlation between the two variables that make a unique and statistically significant contribution to the prediction. if curfew doesn’t issue then the epidemic effect of covid-19 will increase in bangladesh. one the other hand if curfew issue then the epidemic effect of covid-19 will decrease in bangladesh. among 200 respondents, about 96% of peoples said that the curfew issue should be a necessary action for covid-19. as people aren’t conscious of social distance and lockdown rules. they are making any excuse to go outside and the defense force can’t control them. for this reason, the government should have issued curfew as a necessary action to prevent the outbreak of covid-19. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 15 published by scholink inc. table 7. correlations between the epidemic effect of covid-19 will high on bangladesh and if peoples of bangladesh conscious about covid-19 epidemic effect of covid-19 will high on bangladesh if peoples of bangladesh conscious about covid-19 epidemic effect of covid-19 will high on bangladesh pearson correlation 1 -.175 * sig. (2-tailed) .000 n 200 200 if peoples of bangladesh conscious about covid-19 pearson correlation -.175 * 1 sig. (2-tailed) .013 n 200 200 source: author preparation, 2020. it is noticed from the table there was a negative correlation between the two variables that make a unique and statistically significant contribution to the prediction. if peoples of bangladesh are low conscious then the epidemic effect of covid-19 will high on bangladesh. about 72% of people responded that if peoples of bangladesh are not conscious about covid-19, the epidemic effect rate will be high in bangladesh. as peoples of bangladesh are not properly using masks and hand gloves, they are not maintaining social distance. table 8. correlations between the epidemic effect of covid-19 will high on bangladesh and if curfew doesn’t issue for covid-19 epidemic effect of covid-19 will high on bangladesh opening religious places for covid-19 epidemic effect of covid-19 will high on bangladesh pearson correlation 1 .302 ** sig. (2-tailed) .000 n 200 200 opening religious places for covid-19 pearson correlation .302 ** 1 sig. (2-tailed) .000 n 200 200 source: author preparation, 2020. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 16 published by scholink inc. it is apparent from table there was a positive correlation between the two variables that make a unique and statistically significant contribution to the prediction. if open the religious places then the epidemic effect rate for covid-19 will high in bangladesh. about 80% of people responded that it’s the right decision of the government to close all religious places for covid-19. 4.5 prevention and control measures to prevent transmission of infection  avoid physical contact (e.g., hugs, hands shaking, etc.) and social contacts and wash your hand with sanitizer and soap. isolated from the affected people and use mostly vitamin-c for its controlling whiles it is also identified to use chlroqeen for its controlling. besides ginger tea and hot water drink frequently.  wear a face mask that covers the nose and mouth as much as possible, especially when in shared areas. the face mask should be changed frequently; always change the mask when it becomes soiled or wet.  when the face mask is taken off, it should be removed by touching only the elastic bands or strings; front and inside parts should be never touched. hands should be washed/cleaned immediately (and thoroughly) after removing the face mask.  use disposable towels, gloves, and mask if available. if not available, then change towels, gloves, and mask frequently and wash them with regular laundry detergent in a hot-water cycle (90°c). if an item cannot be washed in a hot water cycle, use bleach or other laundry products for the decontamination of textiles.  used gloves, paper tissues, and face masks should be immediately put in the waste bag.  these waste bags can be collected together and placed in a clean general garbage bag.  after handling waste bags, strict hand hygiene should be performed: use water and soap or alcohol-based hand disinfectants.  toilet, bathroom sink, floor, etc. should be cleaned daily, avoiding splashes. surfaces and objects should be disinfected with regular household bleach, in a dilution corresponding to 0.05-0.1% sodium hypochlorite (20 ml of household bleach should be diluted in 1 liter of water). this solution should be used immediately and prepared fresh every time it is needed. 4.6 personal protective measures at home in case of corona virus covid-19  mix 1 teaspoon of bleaching powder in 1-2 liters of water and mix well. if there is a spray bottle, you can fill it with spray bottles. but after 24 hours the bleaching solution will reduce it’s effectiveness.  in any material and metal, wood furniture, plastic, books, paper, steel, fridge, watch, mirror, thai window, toilet, bathroom basin, floor the corona virus survives for 1-5 days. so spray with bleaching water every day. take these items after spraying 10 minutes.  the virus survives for five days in the water glass, tea cups, plates and silver and steel basins. wash them with detergent or veem. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 17 published by scholink inc.  don’t bring any outsiders to home. because the corona virus can now be infected for 14 days without any symptoms. when you talk to a person, you should talk with a mask or a 3-6 foot distance because the virus can spread by breathing. 4.7 personal protective measures on market place in the context of covid-19  gloves, masks and full-sleeved clothes to be worn when you go to the market.  you need to take a polythene bag when you go to the market. you have to take the money in a polythene bag without taking the money in your pocket. because the virus is alive for 6 to 8 hours in the money. you have to go home and throw money out of that polythene bag. we’ll have to catch that money after 24 hours. if you have a coin, you need to wash it in a bleaching wash.  the bag you carry in the market has to be put in the sun, and after 24 hours, you have to catch it.  you have to put the items from the market on paper. the vegetables, fish, and meat from the market should be soaked with 1 to 1.5 teaspoons of baking soda for 10-15 minutes or wet for 1 hour with saltwater.  whoever visits the market will put the goods in the paper. then he will go straight to the bathroom and wash his gloves, masks, and clothes with detergents and take a bath. 4.8 personal protective measures on the workplace in the context of covid-19  gloves, masks and full-sleeved clothes to be worn while going to work.  you need to kill germs desks and tables, laptops, desktop telephones, keyboards with regular germs-kill in your workplace or office.  when you get home from the office, you'll knock the door with your elbows rather than hand. the switch of the elevator or calling bell will touch with the tissue paper.  after entering the house, you have to go straight into the bathroom without touching any person or object. if you have a bag in your hand, you must place it in a specific place so that no one touches. go to the bathroom and wash your clothes with detergents and bath with soap.  put things you carry in the office, such as bags, wallets, mobiles, etc. in a table or a box. spray them with a mixture of bleaching powder and clean them thoroughly.  after taking a bath at home from the office, drink light hot water, tea, lemon juice and take hot steam from hot water. because the virus dies at a temperature of 70 degrees celsius. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 18 published by scholink inc. 5. major finding the study was conducted for two purposes: to assess the human perception to the origin of coronavirus with relation to nature and find out preventative management about coronavirus. according to human perception, about 70% of peoples said “maybe” coronavirus microorganism formed by the impact of climate change, and it’s some factor. in the polar region, there are many ice stacks which among them glaciers and permafrost are natural freezers of the world. thousands of years ago, the dead bodies were buried in a state of unsightly condition. the animals are dead but the virus and bacteria are in a state of sleep. the glaciers and permafrost are melting due to global warming. as a result, thousands of old bodies have begun to be exposed. as a result, the virus, bacteria are starting to live. these viruses including coronavirus will be mixed with different environmental elements such as water, biodiversity. this will easily affect biodiversity and other animals such as bats. there are many countries where these animals are served as food, and then it affects the people. climate change may play a significant role in the transmission of many infectious diseases including coronavirus. climate change is leading us to mass extinction. now, the consequences of global warming are terrible. if climate change continues to escalate, the rate of emergence and re-emergence of infectious diseases will only increase in the future. the correlation analysis results for epidemic effects of covid-19 will high on bangladesh, if immigrant persons come, if curfew doesn’t issue, if peoples are not conscious, if peoples are not properly using mask and hand gloves, if they are not maintaining social distance and lockdown rules. there are some guidelines for prevention and control measures to prevent transmission of infection in the market place and workplace. in the finding that according to regression analysis, correlation, and human perception coronavirus microorganism formed by the impact of climate change. community responses are important for outbreak management during the early phase of major preventive options. 6. conclusion to conclude, we identified human perception towards covid-19 in the community, with the coronavirus microorganism formed by the impact of climate change. most respondents are alert to the disease progression of covid-19 and adopt self-protective measures. precautionary measures were considered: hygienic practices, social distancing, and travel avoidance. enhanced personal hygiene practices (including wearing masks, cleaning hands and better coughing and sneezing etiquette) and avoid traveling to coronavirus affected country. for social-distancing measures were considered useful in preventing covid-19. in the finding according to regression analysis, correlation, and human perception coronavirus microorganism formed by the impact of climate change, this study contributes by examining that if we cannot balance the environment, there are many virus are exposed in the environment. climate change may play a significant role in the transmission of many infectious www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 3, 2023 19 published by scholink inc. diseases including coronavirus. if climate change continues to escalate, the rate of emergence and re-emergence of infectious 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(2003). epidemiology and cause of severe acute respiratory syndrome (sars) in guangdong, people’s republic of china, in 2003 february. the lancet, 362(9393), 1353-1358. https://doi.org/10.1016/s0140-6736(03)14630-2 https://doi.org/10.1016/j.ijantimicag.2020.105924 https://doi.org/10.1016/s0140-6736(05)71146-6 https://doi.org/10.1038/nm1143 https://doi.org/10.1038/nrmicro2147 https://doi.org/10.1586/14787210.5.2.245 https://doi.org/10.2105/ajph.2019.305186 https://doi.org/10.1038/nature12005 https://doi.org/10.4269/ajtmh.16-0696 https://doi.org/10.1128/mbio.00473-12 https://www.who.int/docs/defau https://doi.org/10.1016/s0140-6736(03)14630-2 energy and earth science vol. 3, no. 2, 2020 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 139 original paper recommended optimal land utilization and farming techniques (rolufs) in pendurthi mandal, a geospatial approach, vishakhapatnam district, andhra pradesh, india usha chirala 1* & bhavana pedada 1 1 department of geo-engineering, andhra university, vishakhapatnam, ap, india * usha chirala, department of geo-engineering, andhra university, vishakhapatnam, ap, 530003, india received: september 22, 2020 accepted: october 8, 2020 online published: november 30, 2020 doi:10.22158/ees.v3n2p139 url: http://dx.doi.org/10.22158/ees.v3n2p139 abstract integrating land and water resources is a major key in sustainable development. managing agricultural land is a concerning task keeping the ever increasing population in mind as agriculture utilizes largest amount of water in the world. a case study of pendurthi mandal, vishakhapatnam district, andhra pradesh, india has been taken up for resource appraisal. basic integration of land and water resources (bilwrus), generation of thematic maps using remote sensing in conjunction with geographical information system, and ground laboratory techniques has been the major task. the proposed landuse has been assigned to all the 23 villages of the study area, using recommended optimal land utilization and farming techniques (rolufs) as per the norms set by national water development program for rainfed areas (nwdpra). keywords bilwrus, rolufs, mandal 1. introduction indian civilization was rich and prosperous in the ancient past. however with the ever increasing population and the changing philosophy of the governments, the traditional methods of rural lifestyle and practices have become anachronistic. this has necessitated a change in the outlook and practices in so far as rural living, agriculture, arts, crafts and administrations are concerned. in the light of this application, modern and scientific methods has become necessary and mandatory too. inappropriate and uncontrolled use of natural resources can downgrade their quality and destroy them. sustainable www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 140 published by scholink inc. development and optimized use of natural resources involves effective utilization of the existing resources without damaging the assets and preserves these valuable resources for the future generations. at present, scientific and optimized management of agriculture and natural resources are considered to be important items in sustainable development. in order to achieve sustainability and optimized land allocation we can use linear programming, multi objective linear programming and geographical information system (gis) approaches. watershed planning and management (2018). land use is a crucial link between human activities and the natural environment. large parts of the terrestrial land surface are used for agriculture, forestry, settlements and infrastructure. this has vast effects on the natural environment. land use is the most important factor influencing biodiversity at the global scale. tijanavulević et al. (2018), freshwater availability rosegrant et al. (2002), sala et al. (2000). global biogeochemical cycles, mcguire et al. (2001), and climate brovkin et al. (1999). keeping the above objective in mind, the study area pendurthi mandal of vishakhapatnam district with a total area of 120sqkms consisting of 23 villages, has been taken up for resource appraisal and utilization of its natural resources using modern techniques of remote sensing and gis. with critical study, and analysis of a wealth of information related to the people of the mandal coupled with survey of india toposheets, geological maps, satellite imageries, thematic maps, basic integration of land and water resources (bilwrus) has been generated, and integrated with landuse/landcover. finally proposed landuse for all the 23mandals have been derived from recommended optimal land utilization and farming system (rolufs) as per the norms set by national water development program for rainfed areas (nwdpra). 2. review of literature few studies have been carried out in and around pendurthi mandal and meghadrigedda, the major river that flows through the mandal. among them are identification of soil erosion zones with special reference to silt deposition in meghadrigedda reservoir,usha chirala, ph.d thesis (2013),correlation of geometric parameters for the hydrological characterization of the meghadrigedda watershed, vishakhapatnam, a gis approach, usha chirala et.al. (2012), nageswara rao and narendra, (2009 & 2006), mapping and evaluating the urban sprawl, nageswara rao et al. (2008), on the ground water quality of the meghadrigedda watershed, narendra and nageswara rao (2006), mapping of hydrogeomorphic features in the pendurthi mandal using irs data usha chirala (2003). 3. study area the study area, pendurthi mandal falls in vishakhapatnam mandal in between 17 0 49’30” north latitudes and 82 0 12’13” east longitudes under soi toposheet 650/1 and 0/2&3 on 1:50000 scale (table 1). the total area is 120sqkm, 40m above msl. the mandal headquarters is located 25km north-west of vishakhapatnam and extends for a maximum distance of 20km in the north-south direction and 12km in east-west direction. the vegetation type is deciduous comprising mostly of deciduous dry and deciduous javascript:; www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 141 published by scholink inc. scrub. red soils predominates the area. agriculture is the main economic activity of the people. paddy is the main crop and other crops include sugarcane, groundnut, macrotyloma uniflorum (horsegram), finger millet (ragi) and sesame. there is no irrigation system; the entire activity is under dug wells, bore well and tanks. the number of tanks found after delineation are 108 covering an area of 5.22 sqkm. as per 2020 sentinel-2 satellite data. the location map of the study area is shown in figure 1(a) and the sentinel data of the study area in 1(b). table 1. division of mandals (blocks) narsipatnam division 13 paderu agency division 11 vishakhapatnam division 19 total 43 figure 1(a). location map of the study area www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 142 published by scholink inc. figure 1(b). satellite image of the study area 4. physiography the study area forms part of vishakhapatnam fold belt, and the foliation generally strikes ne-sw. in the central part of the eggb there are four main tectono thermal events dated at 2600, 2200-1900, 1180-950 625-500ma fonarev et al. (1998). majority of the area is plain and under agriculture, with hills in the eastern, northern and southern parts of the mandal. the predominant rock type is khondalite, followed by charnockites, kalonized clay and quartzite. the charnockites occur as outcrops in small patches. some of the big rock (khondalite quarries) are at juttada and chinnamushiwada. laterite with iron oxide concretions is exposed near pendurthi. all the hills inside the study area are khondalites. workable deposits of graphite are reported near narava (figure 2a). figure 2(a). geology map and (b) drainage map www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 143 published by scholink inc. the study area enjoys sub-tropical climatic conditions and the temperature ranges between min 14 0 -20 0 c during the month of december and maximum 33 0 -42 0 c during may. the area receives rainfall during june to december from both south-west and north-east monsoon and the average rainfall is 1110mm per annum (source: zilla praja parishad, vishakhapatnam, andhra pradesh). 5. hydrology of meghadrigedda reservoir the study area has numerous ephemeral streams, and depicts dendritic type of drainage which is found in regions where rocks offer uniform resistance in a horizontal direction. the highest order obtained is 6 th , most part of this particular subbasin comes under the jurisdiction of the study area. meghadrigedda is an east flowing river taking its rise from the eastern ghats from the nandikonda hill. it flows south upto karupavani village and thereafter in south eastern direction until it joins the sea near dolphin’s nose, vishakhapatnam town (figure 2b). meghadrigedda reservoir drains an area of 220.77sqkm . the meghadrigedda reservoir occupies 6.6 sqkm in the study area, hence deserves a mention separately. the geographical dam site is east longitude 83 0 11’27’’ and north latitude 17 0 45’54’’. meghadrigedda reservoir was formed near the confluence of meghadrigedda and narava rivers to supply 8mgd drinking water to the people of the vishakhapatnam city. the flood bank was formed on the left side of the reservoir to protect the howarh-vizianagaram railway line. the frl of the reservoir is fixed at 61.00m. the gross capacity of the reservoir at frl is estimated to be 1169mcft. the dead storage is 1043mcft. the catchment area is under the influence of s.kota, vishakhapatnam, chodavaram and anakapalli rain gauge stations. the catchment is studded with numerous tanks above the full reservoir level. below the reservoir there exists wetland of 510 acres on the right sided which is stabilized under the reservoir scheme. lower riparian rights have been considered while working out the proposals for the reservoir scheme. the catchment area is influenced by both south west and north east monsoons form june to september, and flash floods occur mostly in october and november due to the influence of cyclones in the bay of bengal (source: zilla praja parishad, vishakhapatnam, andhra pradesh). the drinking water facilities are met by 385 bore wells, 15 open wells and 1 piped water supply. the minor irrigation sources are 115, along with 15 sprinklers and 4 drips covering an ayacut of 1835 hectares (18.35sqkm) where tanks cover 1.24sqkm, tube wells 6.55sqkm dug wells 4.55sqkm, sprinklers 0.12sqkm and drip irrigation covering 0.03sqkm as per the year 2018-2019 (source: chief planning officer, vishakhapatnam, andhra pradesh). 6. methodology sentinel data 2 has been georeferenced using survey of india (soi) topographical maps 65o/1 and 65o/2&3 on 1:50000 which cover the study area. the drainage network has been demarcated as a vector layer in *.shp format. individual maps as well as thematic maps have been studied in combination. generation of basic resources and thematic maps using remote sensing in conjunction with ground laboratory technique has been the major task for integration. geology, geomorphology and structural www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 144 published by scholink inc. maps have been combined to achieve at ground water potential zones. basic integration of land and water resources (bilwrus) was generated using slope, soil, hydrogeomorphology and landuse/landcover (table 6). schematic chart showing methodology adopted for integrated resource analysis for the study area is shown in (figure 8). various intersecting polygons have been classified according to combinations, and the two composite maps have been integrated to arrive at recommended optimal land utilization and farming techniques (rolufs). finally present landuse and proposed landuse of the study area has been displayed in table 7. figure 3(a). slope and 3(b) hydrogeomorphology 7. thematic maps 7.1 slope slope, aspect and altitude are the important terrain parameters which influence micro climatic temperature regime and runoff which play a significant role in soil development, vegetation and crop productivity. slope plays a very important role in the utilization of the prevailing land surface. a higher slope contributes very high erosion as compared to lower slope to less erosion. the first paper in which observed slope form is applied to the elucidation of the origin of landforms was studied by sorby (1850) of the origin of the striking steep sided valleys. significant contributions have been made in calculation of slope by wentworth (1930), raisz and henry (1937), robinson (1948), miller (1953), and strahler (1957). highest slopes of more than 15 degrees to 35 degrees are confined to south-western, eastern and norther parts. major part of the area is under less than 1 degree (figure 3(a) and table 2). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 145 published by scholink inc. table 2. contour spacing related to percentage slope 1 slope lower and upper limits of contour spacing 2 0-1 >4cm 3 1-3 1.33-4 4 3-5 0.8-1.33 5 5-10 0.4-0.8 6 10-15 0.26-0.4 7 15-35 0.11-0.26 8 >35 0.11 and less 7.2 hydrogeomorphic units according to jean bhunes, “there is no house or human habitation in the building of which man has not had to take into account the proximity of water” in the archaeological excavations of the saraswati and indus valley civilizations well developed water works came to light. vishnu kautilya (4th century b.c) in his book “artha shastra” mentioned about the importance of water resources in the economy of the state. varahamira (3 rd century b.c) in his book “brihat samhita” discussed about the ground water exploration and quality. extraction of hydrological parameters from remotely sensed data were done as early as by jackson and mcuen (1979) kelly et al. (1977), peck et al. (1981), johnson et al. (1982), peck et al. (1983). hydrogeomorphology deals with the ground water occurrence, its distribution and has the interrelationships with rock types, geological structures, landforms and surface recharge conditions. groundwater potential of any area is mainly dependent on geology (various rock types), geomorphology (different landforms) and structures (lineaments, fractures etc.). the related hydrogeological characters have been considered, evaluated and presented together as hydrogeomorphological units. the occurrence of ground water plays an important role in sustainable agricultural operations. twelve hydrogeomorphic units have been categorized in the study area viz, pediplain moderate, pediplain shallow, structural hills, inselbergs, residual hills, pediment zone and pediment. the three geomorphic units made up of pediplain moderate, pediplain shallow, pediplain and pediment zones dominate the study area, followed by small patches of residual hills and inselbergs (figure 3b and table 3). ground water prospects map of the study area shows a plenty of scope to increase ground water sources. there is no irrigation system; the entire activity is under dug wells, bore well and tanks. the total number of tanks are 108 tanks and tank area is 5.22sqkm, the smallest tank is in juttada covering 0.01sqkm and the largest tank is in pinagadi covering an area of 0.87sqkm (sentinel data 2020, figure 3(b) and table 3). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 146 published by scholink inc. 7.2.1 pediplainmoderate (ppm) there are plain table lands with very gentle to nil slopes (flat table lands) with ground water potential being moderate to good. it has moderately thick 5-20m over burden of weathered material of varying lithology. this unit covers the western and northern parts of the mandal lying in the contour interval of 10-30m. the pediment is overlaid with moderate layer of overburden (cobble to clay). ground water prospects are moderate to good because the unit is adjacent to rivers meghadrigedda and naravagedda. 7.2.2 pediplainshallow (ppm) these are flat and smooth surface of buried pediment with shallow 0-5m of overburden of weathered material of varying lithology. ground water prospects are poor to moderate. this unit mostly covers the eastern part of the mandal, and lies to some extent in western and southern parts, and is between the contours 20-30m. in this layer the pediment is laid with a thin layer of overburden and is exposed to shallow depths. 7.2.3 pediment zone (pz) it is a transitory zone between the debris slope and the next important hill slope element the pediment. nookaraju and vaidhyanadhan (1971). this zone lies in the contour interval of 50-100m. it’s noticeable on the foot hills near the villages porlupalem, cheemalapalli, vepagunta, sowbhagyapuram and mudapaka. being at the foot of the hills they are composed of loose and rocky outcrops with a thin a veneer of detritus. the pediments in this unit have developed on charnockites and khondalites. ground water potential depends on the thickness of the debris. wide pediments have been observed on the eastern and southern sides of the mandal. moderate ground water aquifers are identified in this zone. 7.2.4 pediment (p) pediment as stated by twidale (1976) is a complex phenomenon and single explanation applies to all pediments; several different processes could apparently produce similar landforms. pediment is noticeable in chintagatla, mudapaka and vepagunta villages. it lies in the contour interval of 30-50m. it has a gentle slope and rocky surface. the joints in the khondalites will be the channels of recharge to groundwater. 7.2.5 inselbergs (i) expansion of the pediment or series of pediments may continue until all the remains of the original mountain mass are scattered knolls which rise above its surface. such hills are analogue to mouad rocks on a peneplain surface and were originally and to some extent are still, called insebergs. thornbury (1999). these inselbergs are noticed at four places lying in the contour interval of 100 to 200m near sowbhagyapuram (281 and 211m), mudapaka (169m) and in chintagatla (211m) made of charnockites. the slope of these inselbergs is between 6 to 18 degrees. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 147 published by scholink inc. 7.2.6 residual hills (rh) these residual forms are relic features lift out during scrap retrieval and pediplanation. these boulder maps owe their origin to mineralogical resistance (twidale, 1976) and to primary parting/pacing schumm and chorley (1966) garner (1974). these isolated hills are noticed at two places lying in the contour interval of (80-100m) jerripotulpalem village (96m) and pulagalipalem (98m) and are also made of charnockites. the slope of the hills varies from 12 to 18 degrees. the slope and sparse vegetation accounts to high runoff, hence ground water prospects are very poor. mass wasting is prevalent in the form of soil creep. 7.2.7 structural hills (sh) there are five structural hills, yerrakonda (370m), narava (375m), vepgunta (263m), porlupalem (324m), and near mudapaka (321m). these are made up of well jointed khondalites. the slope of the hills is in between 12 to 13 degrees. the yerrakona hill range in the reserve forest is named after the forest. the narava hill and the reserved forest are named after the narava village. table 3. hydrogeomorphic units of the study area s.no hydrogeomorphic unit area in sqkm percentage of the study area 1 structural hills 17.70 14.75 2 residual hills 0.50 0.41 3 inselberg 0.52 0.43 4 pediment zone 12.03 10.02 5 pediment 3.10 2.58 6 pediment shallow 39.22 32.68 7 pediment moderate 46.02 38.35 8 total 120 100.00 7.3 ground water prospects and water quality ground water hydrology may be defined as the science of the occurrence of the distribution and movement of water below the surface of the earth todd (1980). ground water prospects map is prepared for the study area (figure 4). 92 samples were collected from the 23 villages of the study area (table 4). the hydrochemcial data includes the samples from both bore and open wells for certain parameters like ph, tds, chlorides, flourides, hardness, alakalinity etc. these are determined by using the standard procedures (us salnity laboratory, 1954; usgs, 1996; hem, 1970; apha, 1971) in the laboratory. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 148 published by scholink inc. ph is determined elcetronically with a direct reading called public health meter. chloride is estimated by tritating the water sample against shear nitrate solution (0.005n) using potassium chromate indicator. total alakalinity of water sample is estimated by tritating against standard sulphuric acid using methyl orange as indicator and represented as cacosin mg/l. hardness of the water sample is determined by tritating against edta solution (0.02n) and expressed as mg/l. flouride is determined by the zirinium alizarine method and is expressed as mg/l (figure 5(a), (b) and (c)). figure 4. ground water prospects map figure 5. water quality maps (a) chorides (b) fluroide (c) total hardness www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 149 published by scholink inc. 7.4 soils and soil erodability barring the hills and the water bodies the rest of the area is covered with alluvial soils and red loams and clays the gravelly loams are confined to the peripheral areas of the hills in the eastern and northern part of the study on the basis of the soil map prepared, the soils of the pendurthi mandal have been categorized into alluvial, redloams and clays, gravelly loams and shallow skeletal sandy soils which are confined to the mountains. figure 6(a). the soils of pendurthi are free from salinity hazard, but the study area is subject to varying degrees of erosion hazard depending upon the topographic location. the soil fertility is low to medium, necessitating the application of both organic and chemical fertilizers for obtaining good yields. soil samples were collected for estimation of physical and chemical characteristics in the laboratory (anakapalli soil laboratory, ankapalli, vishakhapatnam district). based on the soil analysis, it can be stated that the soil reaction (ph) is tending to be alkaline. the soluble salt content is normal (less than 0.1mhos/cm). the fertility status in respect of organic carbon is low, available po5 is low to medium attaining good crop yields. the spatial distribution of the soils is shown in (table 5). table 4. chemical analysis of the water samples of the study area no name of the village type of source ph t.d.s total alkalinity as caco3 total hardness as caco3 fluoride as fd chloride as cl nitrate magne-sium as mg iron as fe mg/lit calcium as ca carbonate hardness as caco3 remarks mg/lit mg/lit mg/lit 1 pendurthi (w.a) b. w 7.4 570 135 524 0.2 72 nil 33 nil 116 389 potable 2 pendurthi b. w 6.8 1500 220 324 0.2 256 nil 28 nil 208 104 potable near vet hos 3 jerripotulapalem b. w 8.2 480 200 180 0.6 60 nil 22 nil 90 nil potable 4 mpws mudapaka colony b. w 8.2 570 240 180 0.4 60 nil 20 nil 100 nil potable 5 mpws at gurrampalem o. w 8.2 1680 310 320 0.4 300 nil 50 nil 110 10 excess in tds 6 mpws sr puram b. w 8.2 1630 340 460 0.4 340 nil 36 nil 310 120 excess in tds& calcium 7 juttada o. w 8.2 1390 340 420 0.2 230 nil 44 nil 240 80 potable 8 purushotam b. w 7.3 1200 450 380 0.1 160 nil 60 nil 120 nil potable puram 9 pulagalipalem o. w 7.5 660 260 220 0.4 60 nil 24 nil 120 nil potable 10 chinnamushidwada (mpws) b. w 8 1010 350 400 0.4 160 nil 65 nil 130 150 potable www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 150 published by scholink inc. 11 mpws chimalapalalli o. w 8.5 960 370 240 0.2 100 nil 65 nil 130 150 potable 12 porlupalem o. w 8.5 2580 430 610 0.4 520 nil 112 nil 150 180 excess in tds 13 vepagunta o. w 7.5 920 280 270 0.2 100 nil 30 nil 160 nil potable 14 mpws at peddagadi b. w 7.5 1480 230 280 0.4 270 nil 60 nil 30 50 potable 15 mpws at pinagadi b. w 7.5 730 180 220 0.4 60 nil 43 nil 50 60 potable 16 rampuram b. w 7.5 1090 160 190 0.1 180 nil 34 nil 50 30 potable 17 gorapalli b. w 7 1500 160 320 0.4 340 nil 60 nil 70 160 potable 18 mpws at saripalli b. w 8 1630 230 300 0.6 320 nil 46 nil 110 70 excess in tds 19 rayyayapeta b. w 8 900 240 260 1 70 nil 46 nil 70 20 potable 20 peddagadi elementary b. w 7.5 5240 nil 1860 0.2 1880 nil 136 nil 1300 nil excess in tds, th, cl, mg, ca school 21 saripalli sc colony b. w 8.5 2900 380 480 0.6 660 nil 48 nil 280 100 excess in tds &ca 22 pinagadi nh roadside b. w 8 1010 340 280 0.4 260 nil 49 nil 72 nil potable 23 pinagadi b.w 8.2 1040 220 480 0.2 860 nil 82 nil 143 260 excess in ca hardness 24 pinagadi o.w 8.2 3060 348 1240 0.2 240 nil 288 nil 80 890 excess in tds, th, mg&ch 25 laxmipuram b.w 8.4 1500 296 610 0.2 280 nil 130 nil 64 310 excess in tds, th, ch 26 laxmipuram o.w 8.2 1720 292 630 2 1360 nil 110 nil 170 340 excess in tdh, th&ch 27 laxmipuram o.w 8.4 3120 468 1080 0.3 430 nil 243 nil 56 610 excess in tdh, th&ch www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 151 published by scholink inc. 28 laxmipuram b.w 8.2 1770 260 690 0.2 1540 nil 150 nil 68 430 excess in tdh, th&ch 29 laxmipuram b.w 8.2 1060 380 680 0.3 560 nil 132 nil 142 300 excess in th&ch 30 laxmipuram b.w 8.4 1011 820 664 3 456 nil 153 nil 36 nil excess in th, fluoride and mg 31 laxmipuram b.w 8.6 1040 600 749 1.8 400 nil 151 nil 130 140 excess in th, fluoride and mg 32 laxmipuram b.w 8.5 840 580 372 0.3 200 nil 74 nil 66 nil potable 33 laxmipuram o.w 8.9 890 540 428 1 190 nil 94 nil 40 nil potable 34 pinagadi o.w 8 5610 272 3040 0.2 1300 nil 527 nil 870 2760 excess in tdh, th, cl, mg, ca &ch 35 pinagadi o.w 7.8 1900 332 1300 0.3 2280 nil 277 nil 160 970 excess in tdh, th, cl, mg&ch 36 pinagadi b.w 8.2 1880 590 524 0.3 260 nil 110 nil 42 nil excess in tds 37 pinagadi b.w 8.2 1040 480 240 0.3 140 nil 50 nil 26 nil potable 38 porlupalem b.w 8.8 700 440 340 0.8 200 nil 76 nil 26 nil potable 39 porlupalem o.w 8.7 1120 450 344 2.8 190 nil 68 nil 64 nil excess in fluoride 40 porlupalem b.w 8.8 1700 454 280 2 100 nil 41 nil 110 nil excess in tds& fluoride 41 porlupalem o.w 8.6 3560 510 436 2 260 nil 147 nil 32 126 excess in tds& fluoride 42 pinagadi b.w 8.4 1210 488 932 0.4 336 nil 82 nil 48 nil potable www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 152 published by scholink inc. 43 pinagadi o.w 8.4 1840 362 656 0.2 488 nil 135 nil 96 304 excess in tds, th, ch 44 pinagadi b.w 9 1030 490 472 2.2 280 nil 79 nil 148 nil excess in fluoride 45 pinagadi o.w 8.8 790 548 380 2 190 nil 60 nil 110 nil excess in fluoride 46 pinagadi b.w 8.4 1050 410 368 2 360 nil 77 nil 52 nil excess in fluoride 47 pinagadi b.w 8.5 710 510 280 1.8 140 nil 60 nil 32 nil excess in fluoride 48 cheemalapalli b.w 8.4 700 350 320 2 144 nil 34 nil 180 nil excess in fluoride 49 cheemalapalli b.w 8.5 630 430 268 1.8 80 nil 56 nil 37 nil excess in fluoride 50 cheemalapalli b.w 8.4 650 490 290 1.8 20 nil 63 nil 32 nil excess in fluoride 51 cheemalapalli b.w 8.4 740 580 360 1.8 100 nil 66 nil 92 nil excess in fluoride 52 saripalli b.w 8.4 1830 480 660 0.8 752 nil 138 nil 92 180 excess in tds, th 53 saripalli b.w 8.6 1510 420 652 0.4 508 nil 148 nil 92 280 excess in tds, th 54 saripalli b.w 8.6 1680 440 790 0.8 404 nil 178 nil 40 350 excess in tds, th &mg 55 saripalli b.w 8.5 1190 440 408 0.4 1180 nil 75 nil 90 nil excess in p.h 56 saripalli o.w 9 1320 400 500 0.4 220 nil 114 nil 26 100 excess in fluoride 57 saripalli b.w 9 960 320 220 2.2 160 nil 39 nil 58 100 excess in fluoride 58 saripalli b.w 8.8 780 490 200 2.1 260 nil 34 nil 56 100 potable 59 rajayyapeta b.w 8.6 640 460 52 0.8 68 nil 1 nil 28 100 potable 60 rajayyapeta b.w 8.7 400 280 44 0.4 64 nil 1 nil 28 100 potable 61 rajayyapeta o.w 8.7 400 280 260 0.8 52 nil 56 nil 32 100 potable www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 153 published by scholink inc. 62 rajayyapeta b.w 8.6 620 320 306 0.2 116 nil 58 nil 66 100 potable 63 gurrampalem o.w 9 960 460 370 0.3 462 nil 80 nil 42 100 potable 64 gurrampalem b.w 8.8 1000 400 440 0.6 240 nil 92 nil 60 40 potable 65 gurrampalem o.w 8.8 600 320 330 0.2 88 nil 58 nil 90 10 potable 66 gurrampalem b.w 8.4 840 370 640 1 160 nil 140 nil 52 270 excess in th&ch 67 gurrampalem b.w 8.6 1400 600 210 2.6 360 nil 44 nil 26 nil excess in fluoride 68 gurrampalem b.w 8.2 1300 670 456 1 352 nil 100 nil 40 nil potable 69 mudapaka o.w 8.2 1090 320 260 0.2 310 nil 44 nil 34 nil potable 70 mudapaka b.w 8.6 440 260 220 0.2 100 nil 32 nil 86 nil potable 71 mudapaka o.w 8.7 410 320 200 2.4 40 nil 36 nil 48 nil excess in fluoride 72 mudapaka b.w 8.3 1840 320 836 0.4 740 nil 143 nil 50 560 excess in tds, ch,c 73 mudapaka b.w 8.8 520 380 272 0.6 410 nil 41 nil 100 nil potable 74 s.r. puram b.w 8.4 1000 590 644 0.2 316 nil 151 nil 20 54 excess in th & mg 75 s.r. puram b.w 8.5 820 260 600 0.2 128 nil 126 nil 78 384 excess in th & ch 76 s.r. puram o.w 8.1 960 440 310 0.4 252 nil 60 nil 52 384 potable 77 saripalli b. w 8.4 1400 330 460 0.6 490 nil 92 nil 22 130 potable mpws 78 chinamushivada pwgs b. w 8.6 880 260 460 0.6 138 nil 94 nil 74 200 excess in th, mg, ch etc 79 purushotam b. w 8.6 540 270 280 0.6 50 nil 50 nil 62 10 potable puram pws 80 purushotam b. w 8.5 940 560 440 0.4 150 nil 80 nil 84 nil potable puram pws 81 pendurti ow b. w 8.4 730 280 220 0.3 90 nil 40 nil 53 nil potable 82 mudapaka b. w 8.5 660 210 200 0.4 110 nil 40 nil 32 nil potable 83 gurrampalem o. w 8.4 1900 240 420 0.4 84 nil 94 nil 28 180 potable 84 rampuram b.w 7.8 1600 200 624 0.6 420 nil 115 nil 48 420 excess in th, mg, www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 154 published by scholink inc. ch etc 85 rampuram o.w 8.7 1720 270 490 0.4 500 nil 92 nil 110 270 excess in th, mg, ch etc 86 rampuram o.w 8 1010 260 490 0.4 80 nil 80 nil 84 160 potable 87 rampuram b.w 8 2400 300 1200 0.3 1020 nil 243 nil 200 460 excess in tds, th, cl, mg 88 rampuram o.w 8 2400 300 1140 0.2 1060 nil 219 nil 84 160 excess in tds, th, cl, mg 89 rampuram b.w 8.2 200 260 1080 0.3 910 nil 210 nil 220 420 excess in tds, mg 90 s.r. puram b.w 8.7 1240 300 380 0.8 246 nil 78 nil 55 80 potable 91 rampuram b.w 8.8 980 220 180 0.3 142 nil 37 nil 28 nil potable 92 juttada o.w 8.4 1120 385 0.5 200 nil 77 nil 77 excess in tds note. * b.w( bore well), o.w(open well). figure 6(a). soil and figure 6(b). soil erodibility www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 155 published by scholink inc. soil erodibility map has also been prepared and has been categorized into three categories. figure 6(b). slight erosion(e1) these areas are flat having none to slight degradation in the form of sheet wash resulting in the loss of 0.5cm top soil. moderate erosion(e2). in moderate erosion soil profile loses about 50-75 percent of the soil erosion. severe erosion(e3) when the soil profile has lost the entire surface horizon, and also a part of subsurface erosion, it is said to be severely eroded. table 5. soils of the study area s.no category area in sqkm percentage of the study area 1 alluvial soil 39.22 32.68 2 red loams and clays 41.56 34.63 3 gravelly loams 15.20 12.66 4 shallow skeletal sandy soils 16.45 13.70 5 reservoir 6.60 5.50 total 120 100 7.5 landuse landcover landuse refers to “mans” activities and the various uses which are carried out on the land. landcover refers to natural vegetation, water bodies, rock/soil besides any artificial cover that may result due to land transformation. the terms landuse and landcover are apparently very closely related and are mutually dependent. according to vink (1975), the use to which land in a certain region at a certain time is put to use is known as landuse. based on the 1920 census data (usa) weaver 1954 published a land use map of that country. based on stamps (1950) land utilization system numerous studies were carried out in the eastern european countries. landuse maps were prepared by avery (1965) for the usa and bruyin (1974) for netherlands. the world atlas of agriculture (1973) was based on the landuse survey map of vink (1975). it is estimated that the human footprint has affected 83 percent of the global terrestrial land surface and has degraded about percent of the ecosystems services in the past 50 years alone. land use and land cover (lucc) change has been the most visible indicator of the human footprint and the most important driver of loss of biodiversity and other forms of land degradation (sd21, 2012). the landuse/landcover information mapped have been arranged and grouped into a framework of landuse/landcover classification system primarily developed for interpretation with remotely sensed data. the landuse/landcover has been classified into level i and level ii classes, national remote www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 156 published by scholink inc. sensing center (nrsa) here, the “level” indicates the degree of information content. higher the level, greater will be the information. variations in multispectral responses of the different landcover categories enable detection, identification and categorization of different landuse classes commensurate with the scale of mapping. temporal variability of landuse/landcover evidenced by seasonal changes in water bodies and agricultural crops as well as confusion arising from similar spectral response from the different landuse/landcover classes categories are resolved by resource to multi season remote sensing data and group verification. systematic image interpretation involving detection, identification, classification and codification of the landuse/landcover with reference to image interpretation keys in conjunction with corresponding soi topographical sheets and other ancillary maps were utilized (figure 7 and table 6). figure 7. landuse/landcover 7.5.1 built up land it is defined as an area of human habitation developed due to no agricultural use where the land is covered with residential, transportation, institutional industrial recreational in association. the built up land in this mandal accounts for 15.01sqkm, 8.45 percent of the land area. 7.5.2 agricultural land it is defined as the land primarily used for the cultivation of agricultural crops. the agriculture in the study area is irrigated by tanks and is rainfed. the major crops that are grown in the study area include 7.5.2.1 double crop double crop refers to the standing crop during both kharif and rabi season. it constitutes to 29.86sqkm, i.e., 24.88 percent of the of the study area. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 157 published by scholink inc. 7.5.2.2 kharif unirrigated it is associated with rainfed crops under dryland farming covering 32.85sqkm of the mandal and accounting for 27.37 percent of the landuse. 7.5.3 plantations plantations are clearly identified in the crop lands during rabi season by their relatively low response particularly red and infrared regions related to their internal structure of their foliage and sizable open area of the soil exposed between the trees. major plantations in the region are cashew, casuraina and mango, covering 4.50sqkm and constitute 3.75 percent of the study area. 7.5.4 forests it’s an area within the notified forest boundary having an association of trees and other vegetation types. the total forest area is 10.15sqkm covering 8.45 percent of the study area which is associated with trees and other vegetation cover. the scrub forest is an area of degraded forest mainly due to excessive biotic interference and natural causes which contain mainly bushes and scrubs. the degradation is mainly seen on steep slopes of the hills of the pedurthi and vepagunta area subject to severe erosion. table 6. landuse/landcover landuse category area in hectares area in percentage forest 10.15 8.45 settlements 15.01 12.50 industrial 2.10 1.75 tanks 5.22 4.35 reservoir 6.60 5.50 upland with dense scrub 4.51 3.75 upland with sparse scrub 4.00 3.33 public institution 1.30 1.08 plantations 4.50 3.75 stone quarry 0.07 0.05 mud quarry 1.09 0.90 steep sloping hilly area 2.50 2.08 double crop 29.86 24.88 kharif unirrigated 32.85 27.37 total 120 100 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 158 published by scholink inc. 7.5.5 water bodies this class encompasses surface water bodies either impounded in the form of lakes ponds rivers, etc. 7.5.6 river/stream it is a natural course of water flowing on the land surface along a defined channel. it may be seasonal or perennial. 7.5.7 reservoir/tanks a lake is a large body of surface impounded water natural or artificial within the landmass. tanks are small lakes of impounded water. the reservoir constitutes 6.60sqkm, 5.50 percent of the study area and tanks 5.22sqkm comprising 4.35 percent of the study area. 7.5.8 others industrial and mining are has been combined in the landuse/landcover map. it covers 2.10sqkm comprising 1.75 percent of the study area. figure 8. schematic chart showing methodology adopted for integrated resource analysis in the study area www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 159 published by scholink inc. table 7. basic integration of land and water resources (bilwrus) s.no category lithology geomorpholog y slope % soil land capability landuse groundwater prospects 1 dryland agriculture khondalite pediplain shallow 0-3 redloams and clays ii kharif unirrigated moderate 2 intensive agriculture 1 khondalite pediplain moderate 0-3 alluvial ii double crop good 3 intensive agricluture-2 khondalite pediplain moderate 0-3 redloams and clays iii kharif unirrigated good 4 intensive agriculture-2 khondalite pediplain moderate 0-3 alluvial ii kharif unirrigated good 5 intensive agriculture-4 khondalite pediplain shallow 0-3 redloams and clays iii double crop moderate 6 intensive agriculture-5 khondalite pediment 3-15 alluvial ii double crop poor 7 agro horticulture-1 khondalite pediplain shallow 0-3 red loams and clays iii plantation moderate 8 agro horticulture-1 khondalite pediplain shallow 0-3 alluvial ii kharif unirrigated poor 9 agro horticulture-1 khondalite pediment 0-3 gravelly loams iv kharif unirrigated poor 10 agro horticulture-2 khondalite pediplain shallow 0-3 alluvial ii plantation moderate 11 agro horticulture-2 khondalite pediplain shallow >15 redloams and clays iii plantation moderate 12 agro horticulture-3 khondalite pediplain moderate 0-3 alluvial iii upland with sparse scrub good 13 agro horticulture-4 khondalite pediment zone 0-3 gravelly loams iv plantation poor 14 agro horticulture-5 khondalite pediment 0-3 gravelly loams iv plantation poor agrohorticultu re-6 khondalite pediment zone 5-15 gravelly loams iv kharif unirrigated poor 15 horticulture-2 khondalite pediplain moderate 0-3 alluvial ii plantation moderate www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 160 published by scholink inc. 16 horticulture-2 khondalite pediplain moderate 3-5 alluvial soil ii plantation good 17 horticulture-3 khondalite pediplain shallow 3-5 red loams and clays iii plantation poor 18 afforestation khondalite inselberg >15 alluvial vii upland with dense scrub poor 19 afforestation khondalite pediment zone 0-3 gravelly loams iv dense scrub poor 20 afforestation khondalite structural hill >15 alluvial vii upland with dense scrub poor 21 afforestation khondalite structural hill >15 shallow skeletal sandy soils vii do/ds poor 22 afforestation khondalite structural hill >15 shallow skeletal sandy soils vii dense scrub poor 23 afforestation khondalite structural hill >15 shallow skeletal sandy soils vii dense deciduous poor 24 afforestation khondalite structural hill >15 shallow skeletal sandy soils vii deciduous open/decid uous scrub poor 25 afforestation khondalite structural hill 3-5 shallow skeletal sandy soils vii deciduous open/decid uous scrub poor 26 afforestation khondalite structural hill 5-15 shallow skeletal sandy soils vii dense scrub poor 27 afforestation khondalite structural hill >15 shallow skeletal sandy soils vii dense deciduous poor 28 afforestation khondalite structural hill >15 shallow skeletal sandy soils vii upland with sparse scrub poor www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 161 published by scholink inc. 29 afforestation khondalite structural hill >15 poor 30 afforestation khondalite structural hill 5-15 red loams and clays vii deciduous scrub poor 31 afforestation khondalite structural hill >15 shallow skeletal sandy soils vii dense deciduous poor 32 afforestation khondalite colluvium 5-15 red loams and clays iii dense scrub poor 33 afforestation khondalite structural hill 5-15 shallow skeletal sandy soils vii upland with dense scrub poor 34 afforestation khondalite colluvium 5-15 red loams and clays vii upland with sparse scrub poor 35 afforestation1 khondalite colluvium 5-15 red loams and clays iii deciduous open/decid uous scrub poor 36 afforestation1 khondalite structural hill >15 shallow skeletal sandy soils vii deciduous open/ deciduous scrub poor 37 social forestry-2 khondalite residual hill >15 alluvial vii sparse scrub poor 38 social forestry-5 khondalite pediment zone 0-3 gravelly loams iv steep sloping hill area poor 39 social forestry-5 khondalite pediment zone 5-15 gravelly loams iv steep sloping hill area poor 40 social forestry-6 khondalite structural hill 5-15 gravelly loams iv pediment poor 41 social forestry-6 khondalite pediment zone 5-15 gravelly loams iv kharif unirrigated poor 42 social forestry-7 khondalite structural hill >15 shallow skeletal sandy soils vii upland with sparse scrub poor www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 162 published by scholink inc. 43 social forestry-7 khondalite inselberg 0-3 shallow skeletal sandy soils iv upland with dense scrub poor 44 social forestry-7 khondalite structural hill >15 shallow skeletal sandy soils vii upland with dense scrub poor 45 silvi pasture-2 khondalite pediment zone 0-3 gravelly loams iv upland with sparse scrub poor 46 silvi pasture-3 khondalite pediplain shallow 5-15 red loams and clays iii upland with sparse scrub moderate 47 silvi pasture-3 khondalite pediplain shallow 0-3 red loams and clays iii upland with sparse scrub poor 48 silvi pasture-4 khondalite residual hill >15 red loams and clays iii upland with sparse scrub poor 49 barren stone area khondalite pediplain shallow 0-3 gravelly loams iv mud quarry poor 50 barren stone area khondalite pediment zone 3-5 gravelly loams iv mud quarry poor 51 barren stone area khondalite pediment zone 3-5 gravelly loams iv mud quarry poor 52 barren stone area khondalite structural hill >15 gravelly loams vii mud quarry poor 53 barren stone area khondalite pediment zone 3-15 red loams and clays vii stone quarry poor www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 163 published by scholink inc. table 8. recommended optimal land utilization and farming techniques (rolufs) s.no categories conservation measures i dryland agriculture ku-ppsii vegetation barriers and contour bunding ii intensive agriculture 1) dc-pps, ppm-ii 2) f, ku-ppm, vf-ii, iii irrigation and water management 3) dc-pps, ppm-ii(sodic) field bund maintenance 4) dc-pps, iii 5) p, dc ii iii horticulture 1) p,pps, ppm contour trenches 2) ppm,p, ii 3) pps-ii iv agrohorticulture 1) f, ku, pps,p, iv, v ii, iii 2) ls, pps,p, ii, iii, iv 3) ls, ppm, ii 4) p-pz-iv 5) p-p-iv 6) ku-pz, iv v silvipasture 1) ls-p-v,vi soil and moisture conservation 2) ls-pz,iv sodic 3) pps-ls, iii 4) rh-ls,iii vi social forestry 1) ls-p,v,vi,vii 2) rh, ls,viii 3) pps gully plugging, contour trenches with vegetation hedges 4) ku, hills-vi 5) pz,iv 6) hills, p,vii 7) hills-ls, vii vii afforestation www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 164 published by scholink inc. sf-hills vegetation barriers across waterways. quarrying 1) bsa-hill contour trenches with vegetation hedges. 2) bsa-p the expanded form of the abbreviated words listed in the above table can be seen in table 7. 8. development and management plans inappropriate and uncontrolled use of natural resources can downgrade their quality and destroy them. sustainable development and optimized use of natural resources involves effective utilization of the existing resources without damaging the assets and preserve these valuable resources for the future generations. at present, scientific and optimized management of agriculture and natural resources are considered to be important items in sustainable development. in order to achieve sustainability and optimized land allocation we can use linear programming, multi objective linear programming and geographical information systems (gis) approaches (watershed planning and management 2018). the development of the landuse optimization tool called for a detailed understanding of the variation in productivity and physical characteristics on the field parcel scale, as these conditions are important drivers for land allocation and landuse changes. pirjopeltonen-sainio a et al. (2019). one of the most basic requirements for planning is the availability of timely accurate landuse data at the shortest possible time which was achieved here with the satellite data in the area of land use and more so in the agriculture land use. following activities have been suggested pertaining to the hydrogeomorphology, slope, soil, and ground water prospects on the existing landuse/land cover for all the 23 villages to augment the income of the farmers as agrarian economy prevails in the study area. 8.1 intensive agriculture intensified agriculture which aims at higher yields per unit area. this particular type of cropping involves high amount of labor and money. if it’s practiced in the allocated villages, it will increase the incomes of the families. 8.2 agrohorticulture alongside agricultural crops, horticulture sector has been suggested in the villages with a holistic growth of spices, fruits, vegetables, aromatic plants, coconut, cashew, etc. as nearness to vishakhapatnam city makes a good business for supply of fresh flowers as well. 8.3 horticulture by switching on to species like local berries (ber), cluster beans, gooseberry (aonla) wood apple (custard apple) and pomegranate, the green cover can be increased to eight times. by adopting to drip irrigation the coverage increases to 32 times. the other moisture stress species are guava, cashew, pineapple and manilkarazapota, commonly known as sapodilla (sapota). flowers and aromatic plants can also be encouraged. https://www.sciencedirect.com/science/article/pii/s0264837718319781#! https://www.sciencedirect.com/science/article/pii/s0264837718319781#! www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 165 published by scholink inc. 8.4 silvipasture nourishment of cattle improves their working capacity, milk and meat production. jowar, maize, bajra and horsegram are good fodder crops followed by cowpea, glycine, digitaria, pospalum, and tubers like casava, sweet potato, and arrowroot are some of the crops which can improve the health of the cattle. 8.5 afforestation it grows maximum foliage next to forestry; an activity chiefly looked after the government. wood industries are the chief consumers of plantations and forests, next only to fuel needs. of them housing and paper industry takes the lions share. wood dust boards must be used instead of main trunkbranches, and for paper, mesta based factories must be increased.nap (national afforestation programme) nap scheme aims to support and accelerate the ongoing process of devolving forest protection, management and development functions to decentralized institutions of joint forest management committee (jfmc) at the village level, and forest development agency (fda) at the forest division level. (http://naeb.nic.in/nap_glance.htm). nap scheme could be taken as an aid by the mandal revenue office, and forward the proposed afforestation for the covered villages. hibiscus sabdarifa species yields 12-15 tonnes per hectare, while cannabinus 10 to 17 tonnes/hectare. there are several species which spur out long branches in no time and they must be encouraged. eryhtinaindica (local name, dadap), ficusinfectoria (bunyan) and firligosia (pipa) are all very good to support afforestation, by implanting such ideas biomass growth can be increased. 8.6 social forestry social forestry is an activity of utmost importance to the common man, hence must be practiced anywhere from high moisture zones like tank bunds, water harvesting structures, etc. even broad casting of seeds in rock beds also will yield excellent results. the stress should be laid on local needs, growing a variety of plants and social fencing. neglect of the organic matter of the trees by training at growing stage not only wastes biomasss, but also stunts growth and economy. close density hastens vertical growth, trimming girth, growth, and biomass. social fencing is a must for survival of greenery. 8.7 barren stone area the quarrying is mostly done in the villages on the sides of the barren mountainous area. in the first place heavy quarrying must be stopped by the local government, however if the activity is being carried on with the support of the local or state government, then it must be encouraged in making large plunge holes in the center, in such a way that they become reservoirs of water in the monsoon season, especially near vepagunta village. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 166 published by scholink inc. figure 9. proposed landuse for the study area table 9. current landuse and proposed land use of the study area s.no. name of the village present landuse proposed landuse 1 gorrapalle rabi unirrigated, plantation, double crop dryland agriculture, agrohorticulture-2, 4, intensive agriculture-1, 4 2 saripalle double crop, rabi unirrigated, plantation intensive agriculture-1, social forestry 3 mudapaka upland with dense scrub, upland with sparse scrub, plantation, rabi unirrigated afforestation, silvipasture, agro horticulture-4,6, dryland agriculture 4 gurrampalem upland with dense scrub, upland with sparse scrub, plantation afforestation, horticulture-2, silvi pasture, agro horticulture 5 rajayyapeta double crop, rabi unirrigated, plantation social forestry, dryland agriculture, silvipasture 6 s.r. puram rabi unirrigated dryland agriculture, horticulture-2 7 valimeraka plantation, forest, rabi unirrigated, upland with sparse scrub agro horticulture-2, horticulture-2, intensive agriculture-1, 2, dryland agriculture, afforestation 8 pulagalipalem rabi unirrigated, plantation dryland agriculture, social forestry-2 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 167 published by scholink inc. 9 juttada plantation, double crop agro horticulture-2, horticulture-2, silvipasture 10 chinnamushiwada rabi unirrigated, plantation, settlements dryland agriculture, agro horticulture-1, 2, 4, intensive agriculture-1, social forestry-2, 5, silvipasture-2, afforestation 11 ramapuram plantation, double crop, rabi unirrigated agro horticulture-1,2, horticulture-3 12 pinagadi plantation, double crop, rabi unirrigated, industrial and mining area intensive agriculture-1, agro horticulture-2, dryland agriculture 13 pedagadi double crop, rabi unirrigated, mining area agro horticulture-2, dryland agriculture, horticulture, intensive agriculture-2 14 chintagatla double crop, rabi unirrigated, upland with sparse scrub, plantation agro horticulture-1, silvipasture, social forestry 15 j.r. palem forest, upland with dense scrub, upland with sparse scrub, plantation agro horticulture-4, silvipasture-3, 4 16 narava forest, upland with dense scrub, double crop, rabi unirrigated silvipasture, dryland agriculture, agro horticulture-1, 2, horticulture-3 17 porlupalem upland with dense scrub, upland with sparse scrub, stone quarrying afforestation, silvipasture, intensive agriculture-2 18 chemalapalli upland with dense scrub, upland with sparse scrub, rabi unirrigated, stone quarrying silvipasture-2, dryland agriculture, social forestry, afforestation 19 lakshmipuram double crop, plantation agro horticulture-1, 2 20 krishnarayapuram plantation, rabi unirrigated, industrial area, settlements social forestry-2, intensive agriculture-1, agro horticulture-2 21 purushotampuram rabi unirrigated, settlements, plantation dryland agriculture, intensive agriculture-1, agro horticulture-2 22 vepagunta double crop, upland with sparse scrub, rabi unirrigated, plantation, industrial area, settlements social forestry-2, 5, 7, afforestation, dryland agriculture, agro horticulture-1, 2, 3, 4, silvipasture-2, 3, intensive agriculture-1 23 pendurti double crop, plantation rabi unirrigated, mining and industrial area social forestry, silvipasture-2, dryland agriculture, horticulture www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 168 published by scholink inc. 9. discussions national water development program for rainfed areas (nwdpra) norms have been followed in acheiveng at (bilwrus) basic inegration of land and water resources by integrating drainage, slope, soil, and hydrgeomorphology, which has inturn been overlayed with landuselandcover to arrive at recommended optimal landutilization and farming techniques (rolufs). the prepared bilwrus (table 7) has been set as a guidleine to match with the rolufs (table 8) to arrive at conclusion for a propsed landuse for each and every village (table 9). in table 7, 55 categories of land utlization have been covered as against geology, geomorphology, slope, soil,landcapability, ground water prospects, and as per the pertaining landuse, the propsed land use has been suggested for all the 23 villages with sutiable conservation methods as well (figure 9, table 9). it is essential to develop rural technologies system with a proper setup of delivery modes in growing greens. the covered aspects are silivpasture, horticulture, social forestry afforestation and organic fertilization. rain water strategy could be developed so that water is stored in underground channels during the rainy season when in plenty,and consumed duing the dry season, when water is scarce. this strategy will also complement the bore well technique which is much more expensive and sometimes non-functional. the constructiocn of rural roads must be backed with adequate transportation system so that the rural dweller should be able to transport their agriculture produce to the district headquarters. the farmers could organize marketing of their products to obtain better returns. facilities must be extended to lease out machinary as most of the villagers lack the machinery, and have to expend most of their energy for physical work, their productivity is also very low, and their cycle of poverty becomes a viscous one. in order to allow and maintain continuity in the rural development programs, the government must enshrine rural development programs into law, so that subsequent administration will continue to follow and maintain the program, as it is common practice when one administration leaves power, the subsequent administrations tend to jettison or underplay the previous government programs. proposed land use pattern helps in improving the environmental conditions and rural economic growth, equally helping in sustainable development. acknowledgements the authors wish to thank usgs for the sentinnel data, 2020, junior irrigation officer for the base map, the chief planning officer and zilla praja parishad for the source data. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 169 published by scholink inc. references avery, g. (1965). measuring landuse changes on usda photographs. photo engg, 31, 62-64. brovkin, v., ganopolski, a., claussen, m., kubatzki, c., & petoukhov, v. (1999). modelling climate response to historical land cover change. global ecol. biogeogr, 8, 509-517. https://doi.org/10.1046/j.1365-2699.1999.00169.x fonarev, v. i., konilov, a. n., & rao, a. t. p. (1998). the condition of polymetamorphism in the central parts of the eastern ghats mobile belt. petrology, 6(1), 70-85. garner, h. f. (1974). origin of landscape, a synthesis of geomorphology (p. 734). oxford university press. handbook of statistics. (2019). vishakhapatnam. jackson., & mccuen. (1979). accuracy of impervious area values estimated using remotely sensed data. journal of the american water resources association, 15(2). https://doi.org/10.1111/j.1752-1688.1979.tb00346.x mcguire, a., sitch, s., clein, j., dargaville, r., esser, g., foley, j., & wittenberg, u. (2001). carbon balance of the terrestrial biosphere in the twentieth century: analyses of co2, climate and land use effects with four process-based ecosystem models. global biogeochem, 15, 183-206. https://doi.org/10.1029/2000gb001298 miller, v. c. (1953). a quantitative geomorphic study of drainage basin characteristics in clinch mountain area, virginia and tennessee technical report. 3 office of the naval research, dept. of geology, columbia university, new york. nageswararao, k., & narendra, k. (2006). mapping and evaluation of urban sprawling in the meghdrigedda watershed in vishakhapatnam metropolitan region using remote sensing and gis. current science, 91(11). narendra, k., & nagewara, r. k. (2006). morphometry of meghadrigedda watershed, vishakhapatnam district, andhra pradesh, india using gis and resource data. journal of indian society of remote sensing, 34(2), 101-110. https://doi.org/10.1007/bf02991815 nookaraju, d., & vaidhyanadhan, r. (1971). hill slope elements and surficial deposits near vishakhapatnam, andhra pradesh. journal of indian science association, 13, 45-51. raisz, & henry. (1937). an average slope map of southern new england. geographical review, 27, 412-467. https://doi.org/10.2307/210331 robinson, a. h. (1948). a method for producing shaded relief from areal slope data. surveying and mapping. rosegrant, m. w., cai, x., & cline, s. a. (2002b). world water and food: dealing with scarcity. international food policy research institute, washington, dc, usa. sala, o., chapin, f., armesto, j., berlow, e., bloomfield, j., dirzo, r., & wall, d. (2000). biodiversity—global biodiversity scenarios for the year 2100. science, 287, 1770-1774. https://doi.org/10.1126/science.287.5459.1770 https://doi.org/10.1046/j.1365-2699.1999.00169.x https://onlinelibrary.wiley.com/toc/17521688/1979/15/2 https://doi.org/10.1111/j.1752-1688.1979.tb00346.x https://doi.org/10.1029/2000gb001298 https://doi.org/10.1007/bf02991815 https://doi.org/10.2307/210331 https://doi.org/10.1126/science.287.5459.1770 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 170 published by scholink inc. schumm, s. a., & chorley, r. j. (1966). talus weathering and scarp recession in the colorado plateaus. zeitschriftfür geomorphologie n.f., 10(1966), 11-36. stamp, l. d. (1950). the land of britian: its use and misuse 2ed london longman greens (p. 507). strahler, a. n. (1957). quantitative analysis of watershed geomorphology. geophys union, 38, 913-920. https://doi.org/10.1029/tr038i006p00913 tijana, v. a., mirjana, t., nada, d., & miodrag, z. (n.d.). land use optimization for sustainable development of mountain regions of western serbia. journal of mountain science, 15, 1471-1480. https://doi.org/10.1007/s11629-017-4777-1 tiwadale, c. r. (1976). analysis of landforms (p. 572). john wiley and sons pvt. ltd., australia. usha, c. (2003). geographical review of india (vol. 65, no. 2). usha, c. (2013). identification of soil erosion zones with special reference to silt deposition in meghadrigedda reservoir, vishakhapatnam, india, a geospatial approach (phd thesis). andhra university department of geo engineering, india. usha, c. et al. (2012). correlation of geometric parameters for the hydrological characterization of the meghadrigedda watershed, vishakhapatnam, a gis approach. international journal of engineering science and technology, 4(7), 91-104. vink, a. p. a. (1975). landuse in advancing agriculture. https://doi.org/10.1007/978-3-642-66049-8 weaver, j. c. (n.d.). crop combination regions in the middle west. geographical review, 175-200. https://doi.org/10.2307/212355 wentworth, c. k. (1930). a simplified method of determining the average slope of land surface. amer. jour. sci., 5(20), 184-194. https://doi.org/10.2475/ajs.s5-20.117.184 william, w. t. (1999). principles of geomorphology. world atlas of agriculture. (1973). novara. instituto geografico de agostini. phtonirvacak, 2(1), 19-27. https://doi.org/10.1029/tr038i006p00913 javascript:; javascript:; javascript:; javascript:; https://doi.org/10.1007/s11629-017-4777-1 https://doi.org/10.1007/978-3-642-66049-8 https://doi.org/10.2307/212355 https://doi.org/10.2475/ajs.s5-20.117.184 microsoft word ees-v1n1-p52.doc energy and earth science vol. 1, no. 1, 2018 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 52 original paper use of natural graphite for an energy storage device p. d. d. dilhani1, k. s. perera2, k. p. vidanapathirana2 & k. vignarooban1 1 department of physics, university of jaffna, jaffna, sri lanka 2 department of electronics, wayamba university of sri lanka, kuliyapitiya, sri lanka received: november 12, 2018 accepted: december 10, 2018 online published: december 20, 2018 doi:10.22158/ees.v1n1p52 url: http://dx.doi.org/10.22158/ees.v1n1p52 abstract ever growing high concerns over use of safe and low cost devices have provided a substantial attention on natural materials. as such natural graphite which has been deeply integrated into numerous applications is being received a consideration to be used for electrochemical devices. the main objective of this study is to explore the suitability of sri lankan natural graphite to serve in electrochemical double layer capacitors (edlcs). in order to uplift the safety of the device, a gel polymer electrolyte was used instead of a liquid electrolyte. two identical electrodes were consisted with sri lankan natural graphite as the active material and polyvinylidenefluoride as the binder. to prepare the electrolyte, polyvinylidenefluoride co hexafluoropropylene and magnesium perchlorate were used as the polymer and the salt respectively. cyclic voltammetry test results show that single electrode specific capacitance is depending on the potential window. the percentage reduction of capacitance with continuous cycling was about 28%. nyquist plot of edlc further confirm the capacitive nature at low frequency. keywords natural graphite, gel polymer electrolyte, electrochemical double layer capacitor, cyclic voltammetry, single electrode specific capacitance 1. introduction graphite is one of the natural mineral resources in the world. it has been deeply integrated with diverse range of applications such as industries, transport, defence, medicine and sport. graphite possesses remarkable features. it has high thermal resistance and high electric conductivity. due to that graphite behaves as a metal and also as a non metal. recently, the suitability of natural graphite to be served in electrochemical devices has been deployed mainly due to the reason that graphite structure is capable for ion incorporation which is of utmost importance for electrochemical devices. daunting array of energy and power demands have given rise to new insight for developing energy www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 53 published by scholink inc. storage devices. simultaneously, the global concerns over clean and low cost have given priority for those devices with eco friendly, naturally abundant materials. these issues have raised the motivation towards natural graphite (nr) very much. batteries and conventional capacitors had been the widely used energy storage devices for many years (abruna et al., 2008). to meet the high rising energy demand, those two are not having a substantial capacity. as such, supercpacitors have been introduced which is renowned as a bridge to fill the gap between batteries and conventional capacitors (kim et al., 2015). supercapacitors are two fold namely electrochemical double layer capacitors (edlcs) and redox capacitors. former is based on carbon related electrodes whereas the latter uses conducting polymers and transition metal oxide electrodes. many groups have involved in fabricating batteries using graphite (wang et al., 2017; zhang et al., 2019; lin et al., 2015). but, only a handful of research teams have employed graphite for edlcs (wang et al., 2012). from that portion, none is based on sri lankan natural graphite. the main aim of the present study is to explore the performance of an edlc fabricated using sri lankan natural graphite. as a measure of enhancing the safety, a gel polymer electrolyte has been used instead of a liquid electrolyte which has won a significant interest apart from the drawbacks. 2. experimental 2.1 preparation of nr electrodes nr sample received from bogala graphite lanka (pvt) ltd was used as received. it was first dissolved in isopropanol (aldrich). 20% polyvinylidenefluoride (pvdf-aldrich) was added into the mixture and sonicated well. two fluorine doped tin oxide (fto) glass plates of an area 1 cm2 was cleaned and the slurry was coated on both. then, they were allowed to dry at room temperature. 2.2 preparation of the gel polymer electrolyte (gpe) polyvinylidenefluoride co hexafluoropropylene (pvdf co hfp), magnesium perchlorate (mg(clo4)) were used as received from aldrich without any pre treatment. first, pvdf co hfp was dissolved in acetone purchased from aldrich. mg (clo4) was mixed with the polymer solution and magnetic stirring was done for 24 hrs. the resultant was poured onto a petry dish and allowed solvent evaporation at room temperature. 2.3 fabrication and analysis of the edlc a gpe electrolyte sample having the identical shape and size of fto glass plate electrodes was sandwiched in between the two electrodes. for the edlc, cyclic voltammetry test was done varying the potential window using a computer controlled potentiostat (metrohm autolab m 101). then, cycling was carried out using the same setup to observe the ability of edlc to withstand for continuous charge discharge within the potential window, 0.1 v to 0.7 v. impedance data were collected within the frequency range 0.01 hz – 1 mhz using an impedance analyser (metrohm autolab m101). www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 54 published by scholink inc. 3. results and discussion 3.1 cyclic voltammetry fig. 1 illustrates the cyclic voltammogrammes (cvs) obtained by varying the potential window. figure 1. cyclic voltammogrammes obtained with widening potential window when widening the potential window, the shape of cvs did not change very much. they were in near rectangle shape. this is an characteristic feature of edlcs (kim et al., 2015). but, at higher potentials, current increased tremendously. it may be due to any anodic reaction or electrolyte decomposition (jayamaha et al., 2017). single electrode specific capacitance, cs was calculated using the following equation (tey et al., 2016). cs = 2ʃidv / msv ʃidv is the area of a cv, m is the single electrode mass, s is the scan rate and v is the width of the potential window. continuous charge discharge performance of the edlc is a good indication to exhibit the potential candidacy of an edlc to be employed for practical applications. figure 2 shows the variation of specific capacitance with the cycle number. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 55 published by scholink inc. figure 2. specific capacitance variation with the cycle number charging discharging was done within the potential window from 0.1 v to 0.7 v. this might be possible with the use of a gel polymer electrolyte (sun et al., 2012). using an aqueous electrolyte, this is not possible. anyway, it could be observed a reduction of cs upon cycling. this has been reported by several groups (yuan et al., 2006; meller et al., 2014). the initial cs of 2.05 f/g has reduced to 1.45 f/g during 200 cycles. the percentage of reduction is about 28% which is an encouraging value to carry forward further investigations to improve the performance. 3.2 electrochemical impedance spectroscopy figure 3 is the resulted nyquist plot obtained with the impedance data. figure 3. nyquist plot obtained for the edlc nyquist plots reveal many important properties of a device. some of them are the bulk electrolyte www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 56 published by scholink inc. resistance, charge transfer resistance and capacitive behavior (fletcher et al., 2014). for an edlc, the high frequency region of the nyquist plots represents the resistive properties by semi circles. spike in low frequency region shows capacitive properties (prabaharan et al., 2006). for an ideal capacitor, the spike becomes parallel to the imaginary impedance axis. in the resulted figure, the semicircle that is relevant to the bulk electrolyte is absent due to the insufficient high frequency domain. the semicircle available in the plot is representing the charge transfer resistance. the tilted spike shows the capacitive properties (prasadini et al., 2018). the tilted behavior may be due to some irregularities or roughness of the electrodes. 4. conclusion an edlc was successfully fabricated using sri lankan natural graphite electrodes and a gel polymer electrolyte. this configuration is a novel attempt which is still in its infant stage. cyclic voltammetry results as well as impedance data confer the suitability of the edlc to be employed for applications after some developments. acknowledgements national science foundation sri lanka (rg/2017/bs/02) and wayamba university of sri lanka (srhdc/rp/04/17/01) are highly acknowledged for the financial assistance. references abruna, h. d., kiya, y., & henderson, j. c. (2008). batteries and electrochemical capacitors. physics today, 43-47. https://doi.org/10.1063/1.3047681 fletcher, s., black, v. j., & kirkpatrick, i. (2014). a universal equivalent circuit for carbon-based supercapacitors. journal of solid state electrochemistry, 18, 1377-1387. https://doi.org/10.1007/s10008-013-2328-4 jayamaha, b., dissanayake, m. a. k. l., vidanapathirana, k. p., perera, k. s., & vignarooban, k. (2017). electrochemical double layer capacitors with peo and sri lankan natural graphite. advances in energy research, 5(3), 219-226. kim, b. k., sy, s., yu, a., & zhang, j. (2015). electrochemical supercapacitors for energy storage and conversion. handbook of clean energy systems, john wiley and sons ltd. https://doi.org/10.1002/9781118991978.hces112 lin, m. c., gong, m., lu, b., & wu, y. (2015). an ultrafast rechargeable aluminiumion battery. nature, 520, 325-328. https://doi.org/10.1038/nature14340 meller, m., menzel, j., fic, k., gastol, d., & frackowiak, e. (2014). electrochemical capacitors as attractive power sources. solid state ionics, 265, 61-67. https://doi.org/10.1016/j.ssi.2014.07.014 prabaharan, s. r. s., vimala, r., & zainal, z. (2006). nanostructured mesoporous carbon as electrodes for super capacitors. journal of power sources, 161, 730-736. www.scholink.org/ojs/index.php/ees energy and earth science vol. 1, no. 1, 2018 57 published by scholink inc. https://doi.org/10.1016/j.jpowsour.2006.03.074 prasadini, k. w., perera, k. s., & vidanapathirana, k. p. (2018). 1-ethyl-3-methylimidazolium trifluoromethanesulfonate based gel polymer electrolyte for application in electrochemical double layer capacitors. ionics. https://doi.org/10.1007/s11581-018-2810-1 sun, s., song, j., shan, z., & feng, r. (2012). electrochemical properties of a low molecular weight gel electrolyte for supercapcitor. journal of electroanalytical chemistry, 676, 1-5. https://doi.org/10.1016/j.jelechem.2012.04.028 tey, j. p., careem, m. a., yarmo, m. a., & arof, a. k. (2016). durian shell based activated carbon electrode for edlcs. ionics, 22(7), 1209-1217. https://doi.org/10.1007/s11581-016-1640-2 wang, d. y. et al. (2017).advanced rechargeable aluminiumion battery with a high quality natural graphite cathode.nature communications, 8, 14283-14290.https://doi.org/10.1038/ncomms14283 wang, y., cao, j., zhou, y., ouyang, j. h., jia, d., & guo, l. (2012). ball milled graphite as an electrode material for high voltage super capacitor in neutral aqueous electrolyte. journal of the electrochemical society, 159(5), a579-a583. https://doi.org/10.1149/2.071205jes yuan, c., zhang, x., wu, q., & gao, b. (2006). effect of temperature on the hybrid supercapacitor based on nio activated carbon with alkaline polymer gel electrolyte. solid state ionics, 177, 1237-1242. https://doi.org/10.1016/j.ssi.2006.04.052 zhang m., song, x., ou, x., & tang, y. (2019). rechargeable batteries based on anion intercalation graphite cathodes. energy storage materials, 16, 65-84. https://doi.org/10.1016/j.ensm.2018.04.023 energy and earth science vol. 7, no. 2, 2024 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 27 original paper a new method for producing amino acids and preserving tryptophan by using seafood and waste chen junhao 1 & chen guiqing 1 1 jinan university, guangzhou 510630, china received: november 5, 2024 accepted: november 15, 2024 online published: january 7, 2025 doi:10.22158/ees.v7n2p27 url: http://dx.doi.org/10.22158/ees.v7n2p27 abstract there are many problems in hydrochloric acid hydrolysis, and other acids are preferred. the main problem of hydrolysis is to use acid theory and calculation formula. only the theory can be found from the textbook: the hydrolysis constant k=αnδ, which is problematic and not available. had to establish a new theory and formula: “double chen hydrolysis formula”. tryptophan can be preserved by hydrolysis with citric acid. it does not cause racemization of amino acids. you get l-amino acids, you don’t get d-amino acids. it is neutralized with hydrated lime to form insoluble calcium citrate and filtered out without any impurities. it can also remove heavy metals such as arsenic, cadmium, mercury, lead and chromium. it does not pollute the environment, retains the advantages of hydrochloric acid hydrolysis and overcomes its disadvantages. residual calcium citrate is a good calcium supplement for livestock and poultry—is environmentally friendly. keywords amino acid, hydrolysis, citric acid, calcium hydroxide, triangular conical bottle, reaction still 1. introduction sea (fresh water) products and their leftovers are rich in 17 kinds of protein amino acids, which contain more amino acids such as glycine, alanine and glutamic acid, so the taste is particularly good. it also contains more non-protein amino acids-taurine, which is very important to the human body, is an essential substance for newborn brain development, and has the role of protecting myocardium, anti-arrhythmia, treatment of myocarditis, reducing blood pressure, blood lipids and blood sugar. in addition, it also contains essential elements and trace elements such as calcium, potassium, magnesium, zinc, iodine, selenium and phosphorus. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 28 published by scholink inc. our coastline stretches coastal areas are extremely rich in marine resources! for example, jiaodong area leaves about 2.5 tons of scallop skirt scraps for every 1 ton of wet scallop production. scallop skirts abound throughout the country; a large number of shrimp heads after processing shrimp in various places; a large amount of mussel meat after freshwater pearl is produced in jiang and zhejiang regions. the sea red in some areas of longhai and jiaodong of fujian province, near the wolfi island of zhejiang province, is difficult to sell because of its large output. the cooking juice after processing scallops, jiangyao, clams, sea red and oysters all over the coast is thrown away in large quantities, which can be fully utilized. laver contains up to 32.5% to 39% amino acids, which is very rare and is very good for the production of amino acids and flavorings. worth developing vigorously! amino acids make proteins, without which there would be no life. producing amino acids in large quantities and reducing their price is a necessary means for human health and longevity. the production of amino acids requires a balance of eight essential amino acids for the human body, in appropriate proportion to each other, in line with the fao and the world health organization (fao/who) model. its production methods include hydrochloric acid hydrolysis method, enzyme hydrolysis method, chemical synthesis method and microbial fermentation method. hydrochloric acid hydrolysis method has a long history, high production efficiency, cheap and easy to obtain raw materials, simple equipment, and can produce almost all kinds of amino acids at the same time, without causing racemization of amino acids. you get l-amino acids, you don’t get d-amino acids. but without it, all the tryptophan that humans cannot survive is destroyed. the residual acid can not be removed, the salt generated by neutralization is difficult to remove, the hydrolysis odor generated is difficult to eliminate, and the environment is polluted. because these technical problems can not be solved for a long time, the great potential of hydrochloric acid hydrolysis can not be played out, has been on the edge of elimination, other production methods came into being, to be greatly developed, but they do not have the potential technical advantages of hydrochloric acid hydrolysis method! the biggest advantage of enzymatic hydrolysis is that the conditions are mild, and there is no need for high temperature, high pressure and acid-resistant equipment; the disadvantage is that the reaction time is long, and the hydrolysis is not easy to complete, the enzyme is very fragile, easy to inactivate, and the enzyme is generally more expensive and the efficiency is poor. buffers must be added to stabilize the ph to ensure enzymatic hydrolysis. the inorganic salts produced after enzymatic hydrolysis cannot be removed, seriously affecting the purity of the product! the peptides produced have adverse allergic reactions in some human bodies. tryptophan was obtained by alkaline hydrolysis. some amino acids will racemize, from l-type amino acids to d-type amino acids that the human body can not absorb, and the loss of nutrients is large, and can not be used to produce food. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 29 published by scholink inc. traditional extraction method, chemical synthesis method and microbial fermentation method are difficult to achieve the purpose of industrial production because of the high cost and complex process of precursors. so we find other acids for hydrolysis, but the main problem of acid hydrolysis method is the theory and calculation of acid quantity. from the textbook catalytic theory: hydrolysis constant k=αnδ, α is the catalytic coefficient of acid, n is the molar concentration, δ and hydrolysis temperature t, time t in a certain range is positively correlated. the hydrolysis effect is proportional to n. the theory is flawed. 1) n increases with the decrease of water added. due to the co-ionic effect, it inhibits each other, affecting the ionization of hydrogen atoms, but reducing the hydrolysis effect. 2) this theory fails to reflect the relationship between the amount of hydrolyzed acid and the different types of proteins and the different nitrogen content of hydrolysates. so this formula is not available. we had to build up new theories and formulas. 2. theoretical analysis 2.1 hydrolysis was derived by the acid quantity formula the hydrolysis capacity is only related to the h+ ion in the hydrolyzed acid molecule. for many (y) elementary acids, an acid molecule with y h atoms may ionize into h+ ions. therefore, the hydrolysis effect is related to the equivalent number of hydrolyzed acid. the purpose of hydrolysis is to break the polypeptide chain of nitrogen molecules in the raw material into free amino acids. the more the number of nitrogen molecules in the raw material, the more the equivalent number of hydrolyzed acid is required. this is a proportional relationship, written as the equation: equivalent number of hydrolyzed acid=number of raw nitrogen molecules ×cc...... (1), the proportional coefficient cc is called “double chen hydrolysis coefficient”, referred to as “hydrolysis coefficient”. ∵ molecular number of hydrolyzed acid=weight of hydrolyzed acid/molecular weight of hydrolyzed acid; equivalent number of hydrolyzed acid=number of molecules of hydrolyzed acid ×y=(weight of hydrolyzed acid ×y)/molecular weight of hydrolyzed acid...... (2); raw material nitrogen molecular number=raw material nitrogen content/molecular weight of nitrogen 14.0067...... (3). substitute (2) and (3) into (1): (weight of hydrolyzed acid × y)/molecular weight of hydrolyzed acid=(nitrogen content of raw material /14.0067) ×cc. ∴ hydrolytic acid weight=(molecular weight of hydrolytic acid / 14.0067) × nitrogen content of raw material ×cc ÷y =(molecular weight of hydrolyzed acid/14.0067) × raw protein content ×16%×cc÷y...... ⑷ double chen hydrolysis formula. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 30 published by scholink inc. general meat, poultry, eggs, fish, shellfish protein nitrogen content is 16%. 2.2 find suitable cc and hydrolysis acid 2.2.1 double chen hydrolysis coefficient cc strong acid catalytic coefficient is high, cc can be smaller. hard protein consists of bone, tendon, horn, hair, silk and other substances with large protein content, cc can be larger. cc is negatively correlated with hydrolysis pressure, temperature t, time t and air temperature. this is presented as table 1 cc values for reference! 2.2.2 acid for hydrolysis 2.2.2.1 inorganic acid iodate and bromate are dangerous or carcinogenic substances. sulfuric acid is a binary strong acid, which is easy to injure and destroy things. nitric acid is too aggressive. it explodes. phosphoric acid has a burnt taste. hydrochloric acid polluted the environment, destroyed tryptophan, and the salt neutralized by hydrolyzed residual acid was difficult to remove. they are not suitable for use! 2.2.2.2 organic acids because it is necessary to neutralize the residual acid with lime after hydrolysis, it is necessary to consider the saturated solubility of its calcifiers, which is too large to be easily removed, preferably below 0.1, and it is also necessary to consider the taste. saturated solubility of the following organic acid calcifiers (g/100ml) calcium formate 16.725. calcium acetate 34. calcium propionate 28.3, low threshold, bad smell. calcium tartar 0.38, too exciting. calcium lactate 4.54. calcium gluconate 4.012. apple calcium 0.8. calcium oxalate 0.00067, taste heavy not available. calcium citrate 0.0825, the best hydrolysis with citric acid, the catalytic coefficient α is acceptable, does not pollute the environment, the residual acid after hydrolysis is neutralized by hydrated lime to form calcium citrate precipitation, filtration removal, does not contain impurities, and preserves the very important tryptophan for the human body. the equipment is simple, the raw materials are cheap and easy to obtain, and the advantages of hydrochloric acid hydrolysis are retained and its disadvantages are overcome. the disadvantages of citric acid hydrolysis are low catalytic coefficient and large dosage, and reflux hydrolysis is only used for experimental purposes. the production must be hydrolyzed using a reactor. alkaline hydrolysis is used to obtain tryptophan only. most amino acids are racemic and do not produce food. enzymatic hydrolysis is costly and inefficient. neutralization produces inorganic salts that cannot be removed. residual calcium citrate is the best calcium supplement for livestock, which is conducive to environmental protection! www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 31 published by scholink inc. 3. experimental equipment and method 3.1 hydrolysis equipment and conditions 1) reflux hydrolysis of 5l triangular cone bottle. with a 5l triangular cone bottle, plus a rubber plug, plug in the condensation tube, and connect the tap water to cool the hydrolyzed steam, so as not to burn the hydrolysate dry. it was heated in a temperature controlled electric furnace of 1500w and hydrolyzed at one atmosphere (1kg pressure) and 100 0 c for 12 hours. take care to regulate the temperature to prevent excessive boiling and dry the hydrolysate liquid. 2) reactor hydrolysis. use electric heating or oil heating 304 stainless steel reactor, volume according to need. with an anchor mixer. run the blender at regular intervals for 10 minutes. be careful not to fill the reactor too full, 70% can be. hydrolysis at 2kg pressure, 112-118 0 c for 12 hours. be careful not to heat too much to avoid a burnt taste. 3.2 citric acid hydrolysis. the raw material is hydrolyzed by adding citric acid and appropriate amount of water 3.2.1 calculation of acid quantity for hydrolysis citric acid c6h8o7 (192.125), ternary weak acid y=3. the ionization constant kα1=7.4×10 -4 , kα2=1.7×10 -5 , kα3=4.0×10 -7 . the citric acid required is calculated from formula (4): m hydrolytic acid=(molecular weight of hydrolytic acid/14.0067) × raw protein content ×16%×cc÷y m citric acid=(192.125÷14.0067)×(weight of raw material×protein content of the raw material) ×16%×cc÷3 =weight of raw material×protein content of raw material ×cc×0.7315=weight of raw material×nitrogen content of raw material ×6.25×cc×0.7315...... 5. add appropriate amount of water for hydrolysis. m stands for weight. select cc refer to table 1. 3.2.2 neutralization of food grade hydrated lime m calcium hydroxide=(222.284÷384.251)× m citric acid=0.5785×m citric acid... [6] in order to prevent residual calcium hydrogen citrate cah(c6h5o7) and calcium hydrogen citrate cah4(c6h5o7)2 from precipitating into calcium citrate ca3(c6h5o7)2, and to completely remove heavy metals, so that the hydrolysate reaches ph12-13, more hydrated lime is added for this purpose. since the saturated solubility of hydrated lime ca(0h)2 at 20 0 c is 0.16(g/100g), ph12-13 is reached at this time. excess lime can be filtered out, and the saturated solubility of lime in the solution of 0.16g/100g will not affect the subsequent treatment. 3.2.3 after 3 hours of precipitation, filter 3.2.4 post-processing under the strong alkaline ph12-13, the hydrolysate is neither delicious nor can amino acids be measured, and it is necessary to adjust it to weak acidity with acid. if neutralized with citric acid, small amounts of calcium hydrogen citrate cah(c6h5o7) and calcium hydrogen citrate cah4(c6h5o7)2 may be produced to precipitate. cacl2 solution was formed by neutralization with food-grade hydrochloric www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 32 published by scholink inc. acid. the original ca(0h)2 had a saturation solubility of 0.16(g/100g), and the resulting cacl2 had a solubility of 0.23g/100g, which would not precipitate (the saturation solubility of cacl2 at 20 0 c was 74.5%). with food grade hydrochloric acid 0.157g/100g can be neutralized to ph7. it is best to add more hydrochloric acid to reach about ph5 and taste better. 2hcl + ca(oh)2——→ cacl2 +2 h2o 72.922 74.09468 110.99 m cacl2=(110.99÷74.09468)×m ca(oh)2=1.4979×0.16g/100g=0.23g/100g mhcl=(72.922÷74.09468)×m ca(oh)2=0.9842×0.16g/100g=0.157g/100g 3.2.5 expected production v (volume) according to the definition of extraction rate γ=product nitrogen content÷raw material nitrogen content =[product volume v(ml)×product specified amino nitrogen content (g/ml)]÷[raw material weight (g)×nitrogen content of the raw material %]. ∴ product volume v(ml)=[raw material weight (g)×nitrogen content of the raw material %×γ]÷amino nitrogen content specified in the product (g/ml). ∵ nitrogen content of raw materials %=raw material protein content %×16%; product volume v(ml)=raw material weight (g)×protein content of the raw material %×16%×γ÷amino nitrogen of the product (g/ml)…⑺ reactor hydrolysis γ=50%~70%, reflux hydrolysis temperature is greatly affected by temperature, especially in winter, γ=35%~50%. 3.3 the hydrolysis capacity of citric acid is weaker than that of hydrochloric acid, and it is more suitable for hydrolyzing seafood with protein content below 30% 4. experimental results and analysis scallop skirt was boiled and concentrated into scallop liquid (table 2), which contained 4.82% total amino acids. calculate the citric acid to be added from (5), add appropriate amount of water for reflux hydrolysis for 12 hours, hydrated lime neutralization, long-term precipitation, filtration and post-treatment. 4.1 experiment 1 scallop solution 2,120ml, select cc=5.1. add 422g citric acid. after hydrolysis, hydrated lime neutralization, long-term precipitation, filtration and “post-treatment”. scallop hydrolyzed juice 1,300ml. as shown in table 3, the total amino acid content is 2.81%. the extraction rate was γ=35.7%. 4.2 experiment 2 laver 180g, cc=7. add 300g citric acid. after hydrolysis, hydrated lime neutralization, long-term precipitation, filtration and “post-treatment”. seaweed seasoning liquid 1640ml. as shown in table 5, the total amino acid content is 1.26%. extraction rate: γ=35.3%. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 33 published by scholink inc. the above two experimental testing companies could not detect tryptophan, so they had to change to zhongke company for testing, as shown in table 6. 4.3 experiment 3 scallop solution 2100ml, cc=6.75. add citric acid 138.2g. after hydrolysis, hydrated lime neutralization, long-term precipitation, filtration and “post-treatment”. 1,730ml of scallop juice. as shown in table 7, the total amino acid content is 2.4% and tryptophan 0.09%. the extraction rate was γ=41%. 4.4 experiment 4 laver 83g (table 4), select cc=8. add 142g citric acid. after hydrolysis, hydrated lime neutralization, long-term precipitation, filtration and “post-treatment”. get laver juice 260ml. as shown in table 8, the total amino acid content is 5.1% and tryptophan is 0.15%. the extraction rate γ=49%. 4.5 experiment 5 pinctada martensii meat 750g, with citric acid 440g. after hydrolysis, hydrated lime neutralization, long-term precipitation, filtration and “post-treatment”. the total amino acid content was 3.27%. the extraction rate γ=(1300×3.27%) ÷(750×14.3%)=39.6%. 4.6 experiment 6 1000l stainless steel reactor is adopted. scallop skirt 270kg, contains 8.8% protein, select cc=2, add citric acid 35kg. after hydrolysis, hydrated lime neutralization, long time precipitation, filtration and “post-treatment”. i have 500 liters of scallop juice. contains 0.4% amino nitrogen. extraction rate: γ=500×0.4%÷(270×8.8%×0.16%)=52.6%. acceptance, smooth delivery. 5. conclusion 1) the “double chen hydrolysis formula” for calculating the amount of acid used for hydrolysis is derived, and the concept of “double aging hydrolysis coefficient cc” is introduced. 2) citric acid hydrolysis retains the advantages of hydrochloric acid hydrolysis and overcomes its disadvantages. after hydrolysis, it is neutralized with hydrated lime to produce calcium citrate precipitation, which is filtered to remove hydrolyzed residual acids, bases, salts and all heavy metals: as,cd, hg, pb, cr, etc. does not pollute the environment. the equipment is simple, high efficiency, raw materials are cheap and easy to obtain, can produce amino acid, seasoning, compound condiments and so on. suitable for hydrolysis of aquatic products, 3) seafood hydrolysis to taurine, very important to the human body. 4) the head of prawn has many whiskers and shells which are difficult to handle. amino acids can be extracted by hydrolysis with citric acid and flavoring can be produced. 5) the hydrolysis of citric acid does not occur racemization to obtain l-amino acids, and does not produce d-amino acids. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 34 published by scholink inc. 6) the citric acid hydrolysis method removes all salts and impurities, preserving the most important tryptophan for the human body. push enzymatic hydrolysis and alkaline hydrolysis off the technical stage, no need to use them! 7) residue is a good calcium supplement for livestock and poultry, which is conducive to environmental protection attached test report table 1. hydrolysis reinforcement coefficient cc reference value table 2. experimental scallop liquid www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 35 published by scholink inc. add too much water to increase cc. table 3. experiment 1 results of hydrolyzed scallop juice table 4. experimental laver www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 36 published by scholink inc. table 5. experiment2 hydrolyzed laver juice table 6. tryptophan in hydrolyzed scallop and laver juice www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 37 published by scholink inc. table 7. experiment 3 all amino acids in scallop liquid table 8. experiment 4 all amino acids in laver www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 38 published by scholink inc. table 9. experiment 5 test of hydrolysate table 10. experiment 6 the application of citric acid hydrolysis technology in the production of fresh scallop juice using a reactor in yantai city, shandong province, china, won the “national patent technology invention gold award”. total amino acid氨基酸总量。gly 甘氨酸。ala 丙氨酸。val 缬氨酸。leu亮氨酸。ile 异亮氨 酸。phe 苯丙氨酸。trp 色氨酸。tyr 酪氨酸。asp 天冬氨酸。his 组氨酸。asn 天冬酰胺。 www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 39 published by scholink inc. glu 谷氨酸。lys 赖氨酸。gln 谷氨酰胺 met 甲硫氨酸。arg 精氨酸。ser 丝氨酸。thr 苏氨 酸。cys 半胱氨酸。pro 脯氨酸。 references academic proceedings on amino acids (pp. 1-192). (1983.). amino acid laboratory, wuhan university. amino acids and biological resources. (n.d.). journal of amino acids and biological resources. school of life sciences, wuhan university. amino acids and human health. biotechnology and application graduate thesis. (n.d.). jining vocational and technical college. chen guiqing, & chen junhao. (2006). methods for producing condiments by hydrolysis of organic acids. in chinese spiritual civilization treatise volume iii comprehensive treatise (pp. 341-343). central literary publishing house. new trends in research, development, production and application of amino acid production by fermentation at home and abroad. kou guang will wait. (n.d.). school of bioengineering, tianjin university of science and technology. production method of amino acid liquid of pearl oyster or ginseng of pearl oyster. (2017). patent no. zl 2015 1 057130.x. authorization date november 21, 2017. production status, development trend and existing problems of amino acid industry in china. (n.d.). school of bioengineering, jiangnan university. research report on production technology of amino acid solution. (n.d.). chemical market information network. energy and earth science vol. 7, no. 1, 2024 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 10 original paper textbook error theory about aragonite structure chen guiqing 1 & chen junhao 1 1 guangzhou jinan university 510630, guangzhou, china received: november 25, 2023 accepted: december 7, 2023 online published: march 25, 2024 doi:10.22158/ees.v7n1p10 url: http://dx.doi.org/10.22158/ees.v7n1p10 abstract science constantly discovers new theories and concepts, overturning erroneous theories and concepts. textbooks never correct, fallacies are left to future generations. there are two erroneous theories about the structure of aragonite in textbooks: (1) the authoritative chinese textbook “outline of shellfish studies” by zhang xi and qi zhongyan believes that shells can be divided into three different crystal structures, with the middle layer being a prismatic layer that occupies the majority of the shell and is composed of calcite (cubic crystal system, hexagonal crystal cells). the shellfish academic community in china quotes many japanese literature, and these theories may have been copied from japan. (2) the geological crystallography book records that the structural physical properties of aragonite are unstable and will eventually transform into calcite. we use x-ray derivatives found that after a long geological time, aragonite not only did not become calcite, but also the grain is growing large: monocrystalline, calcite is still decreasing, calcite is changing to aragonite. keywords marine biology, x-ray diffraction, shell, prismatic pearls, aragonite structure, calcite structure, geology and crystallography 1. introduction recently, we consulted renowned shellfish scientist xie yukan from the south china sea institute of oceanography, chinese academy of sciences to discuss this issue. it is understood that his graduate students still believe that the prismatic layer of the shell is composed of calcite through microscopic verification. do shellfish scientists still not know that crystal structure can only be determined by x-ray diffraction, or by observing morphology under a microscope? the german physicist roentgen discovered x-rays on november 8, 1895! in 1959, shinjiro kobayashi and tetsuko watanabe from japan proposed that prismatic pearls have a calcite structure. many domestic and foreign papers have not raised objections to this, which is wrong. japanese shellfish scientists are also unfamiliar with www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 11 published by scholink inc. crystallography. what changes will occur when shells are buried in the ground for thousands of years? the geological crystallography book records that the physical properties of aragonite structure are unstable and will eventually transform into calcite, which has become common knowledge. wrong, it's the transformation of calcite into aragonite structure. aragonite gemstones are composed of minerals such as aragonite, calcite, iron oxide, and opal, and belong to secondary minerals with aragonite as the main component. only xizang, penghu in taiwan province and sicily in italy produce aragonite gemstones in the world. in theory, there should not be any aragonite gemstones in the world, because after billions of years, all the aragonite structures it contains have already transformed into calcite structures. however, in reality, they still exist, indicating that this theory is incorrect. 2. materials and methods 2.1 modern shells the following shells are provided by xie yukan, sanya director of the south china sea institute of oceanology, cas. pinctada martensi, pinctada maxima, hyriopsis cumingii, cristaria plicata, pteria (magnavicula) penguin, pinctada margaritifera, pinctada nigra, pinctada chemnitzi, anodonta woodiana, lamprotula mansuyi, mactra antiquate, arca (anadara) granosa, meretrix meretrix, perna viridis, tridacna (chamestrachea) squamosa, (meretrix meretrix), nautilus pompilius, trochous nilotticus, turbo chrysostomus, erosaria caputserentis, trachycadium flavum, macoma truncate, corbicula fluminca， haliotis diversicolor, nerita albicilla, mytilus edulis, spondylus nicobaricus, chama dunker and abra profundorum. the pearl and shell is ground into powder with agate mortar and passed through a 360-mesh screen. using the d/max-1-a type x-ray diffractometer, using the cu target kα ray diffraction, under the conditions of 40kv and 50ma, within 30min from 2θ range 20 0 -80 0 , the instrument uses the plot plotter, automatically prints 2θ, the absolute intensity i and the corresponding crystal face group spacing d. refer the above results to the international universal phase analysis (jcpds) card to determine the crystal structure of the sample. d=0.1974nm, and the bottom crossbar of the spectral line has an aragonite structure. d=0.3030nm, and the dashed line at the bottom of the spectral line shows a calcite structure. d=0.3019, the calcite iii structure with ripple at the bottom of the spectral line, and the silica structure with rod, point, and rod at the bottom of the spectral line with d=0.3336. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 12 published by scholink inc. 2.2 ancient shells in the 1980s, huang baoyu, a researcher at the nanjing institute of paleontology, provided four kinds of ancient seashells, such as splitodonta, splitodonta radiata, euhylidia dui and liunia, which were collected from 102 points in ding village, xiangfen, shanxi province, and were all hundreds to thousands of years old. borrowed four ancient shells from dr. tan yehui and dr. chen zhiyun of the south china sea institute of oceanography in guangzhou: the clams marmosa, the smooth blue clams, the river clams and the great clams. the first three species were collected from the late quaternary loose sedimentary rock center of yuanzhou production team 1 well, shunde, guangdong province. in the early 1970s. the fourth kind was extracted from longan village water conservancy project in shunde, guangdong province. years 500 to 1,000 years. grind as above into powder and pass through 360 mesh screen. it was diffracted by empyrean x-ray diffractometer. 3. experimental results 3.1 pearl layer structure of shells only the pearl layer of the ostrea rivularis shell has a calcite structure. the white inner layer of the pinna atropururea shell is also a aragonite structure, and the black luminescent part around it is a calcite structure, which is also considered a pearl layer. the pearl layer of the other shells is entirely composed of aragonite structure. explain that the above theory is correct. 3.2 prismatic layer structure of shells at present, only the prismatic layer of the pinna atropura shell is found to be a ca1cite structure, while the loose part of the ostrea rivularis shell is a calcite ca1cite-iii structure. the prism layers of the other shells are all aragonite structures. this indicates that the above theory is incorrect. some shells are too thin to be layered, so they have to undergo full shell x-ray diffraction. the majority of the entire shell of spondylus nicobaricus, haliotis diversicolor, nerita albicilla, mytilus edulis, chama dunker, and abra profundorum are also aragonite structures. 3.3 the periostracum layer structure of shells contains a large amount of amorphous organic matter. some shells also contain aragonite structures. some shells also contain calcite structure ca1cite. the “outline of shellfish science” states that it is incorrect for the stratum corneum of shells to be composed solely of “conchiolin”. 3.4 prismatic pearls are all of aragonite structure, without calcite structure 3.5 schistodesmus sp. prismatic layer wilderness number ady201, 1983/9/9. all spectral lines are aragonite structure, no impurity spectral lines. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 13 published by scholink inc. 3.6 schistodesmus lampreyanus (baird & adams) prismatic layer wilderness number ady201, 1986/12/16. all spectral lines are aragonite structure, no impurity spectral lines. 3.7 unio douglasiae griffith et pidgeon wilderness number ady201,1986/12/16. 3.7.1 unio douglasiae pearl layer the only weak spectral line of calcite appears, with a relative aragonite content of 0.15% in calcite. all other spectral lines are aragonite structured. 3.7.2 unio douglasiae periostracum layer all spectral lines are aragonite structure. 3.8 lamprotula hazinic (heude) shell wilderness number ady193, 1986/12/16. 3.8.1 lamprotula hazinic pearl layer all spectral lines are aragonite structure, no impurity spectral lines. 3.8.2 lamprotula hazinic prismatic layer the only weak spectral line of calcite is d104=0.3034nm. the relative content of calcite is 0.23%. all other spectral lines are of aragonite structure. 3.8.3 lamprotula hazinic periostracum layer the only weak spectral line of calcite is d104=0.3024nm. the relative aragonite content is 0.17%. all other pectral lines are aragonite. 3.8.4 pearl cores made from modern lamprotula hazinic shells all spectral lines are aragonite structure. 3.9 trapezidae, trapezium liratum (reeve, 1843) periostracum layer the results are shown in table 1, the same below. two strong silica spectral lines appeared with d=0.3370nm and i/i0=70.2%; d=0.1824nm, i/i0=56.00%, which is the silica that ancient shells have adhered to in soil for many years, because modern shells have never seen these spectral lines; all other spectral lines are of aragonite structure. 3.10 corbulidae, potamacorbula laevis (hinas) periostracum layer all spectral lines comply with card 041-1475, all pectral lines are aragonite structure, no impurity spectral lines. 3.11 corbiculidae, corbicula fluminea (müller) 3.11.1 corbicula fluminea prismatic layer all spectral lines are aragonite structure, no impurity spectral lines. 3.11.2 corbicula fluminea periostracum layer the majority of the spectral lines below the second strongest in the table are aragonite structures. two weak calcite spectral lines appeared: d104=0.3033nm, i/i0=8.71%, and d113=0.2282nm, i/i0=7.26%. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 14 published by scholink inc. the strongest spectral line of aragonite is d=2697nm, and i/i0=67.1%. the strongest spectral line of calcite is d=0.3033nm, and i/i0=8.71%. the relative aragonite content of calcite is 1.2%. the strongest spectral line d=0.3336nm is the strongest spectral line of silica sio2, and the spectral line d=0.4249nm is the second strongest spectral line d100=0.4255nm of silica sio2. there is also a spectrum line d=0.3205 nm and i/i0=18.38%, which is unknown. the stratum corneum of river clams contains a high amount of silica, which has been stuck in the soil for many years, because modern shells have never seen these spectral lines. if it is removed, it still has a relatively complete aragonite structure, and the aragonite spectral lines of ancient river clam shells are the same as those of modern river clam shells, without any changes. 3.11.3 modern corbicula fluminea prismatic layer the only weak impurity mass spectrum line appeared, d=0.3632nm, i/i0=3.21%, and all other spectral lines are of aragonite structure. 3.12 corbiculidae, corbicula maxima prismatic layer excavated from the longyan village water conservancy project in shunde, guangdong. collection time: february 1961. 3.12.1 corbicula pearl layer the x-ray diffraction pattern is very special, with the absolute intensity of the strongest spectral line d=0.2875nm reaching i=4290.7 (the maximum intensity of the spectral line in a typical shell is about 700). the spectral lines are very strong, narrow, and few, all of which are thick aragonite grains with a strong “single crystal tendency” and no impurities. unlike geological crystallography, where the structure of aragonite is unstable, it will eventually become calcite. instead, it develops towards a higher degree of crystallization, indicating that the structure of aragonite is stable. according to the scherrer formula of x-ray diffraction theory of crystals, the strengthening, narrowing, and decreasing of spectral lines are caused by the growth and thickening of grains in this diffraction direction (preferential orientation growth), which we refer to as the “single crystal tendency”. the growth process of the shell pearl layer is the process of aragonite crystal growth, constantly in an unbalanced state. due to vacancies or impurities filling the lattice, the lattice distortion changes the crystal plane group spacing d, causing the spectral lines to widen and continuously generating new internal stresses. after the death of shellfish, crystal growth stops and no new internal stress is generated. the stress inside the shell gradually releases, vacancies are gradually filled or impurities are gradually eliminated to the grain boundary to eliminate internal stress. at this time, internal stress is also concentrated at the grain boundary, so this area is prone to weathering. the grains of aragonite continue to grow, therefore; make the spectral lines stronger, narrower, and fewer! due to the large size of the clam shell, it is less affected by the surrounding soil, which better reflects this process. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 15 published by scholink inc. 3.12.2 corbicula prismatic layer it x-ray diffraction pattern of the prismatic layer of the clam shell is similar to that of the pearl layer, with strong, narrow, and few spectral lines. all spectral lines are thick aragonite grains with a “single crystal tendency”, and there are no impurity spectral lines. the prism layer is between the nacre and the stratum corneum, and the internal stress release is slower, so the spectral lines are slightly more than the nacre. 3.13.3 corbicula periostracum layer all spectral lines are aragonite structure, no impurity spectral lines. according to the x-ray diffraction diagram of the corneum of large corbicula shell on the right of fig.1, the absolute intensity of the strongest spectral line d=0.1980nm i=481.16. due to the large amount of amorphous organic matter in the corneum, the monocrystallization is affected, which greatly reduces the absolute intensity and slightly increases the spectral line. once again proved the ancient shell monocrystalline trend! table 1. x-ray diffraction data various shells pinctada martensi pearl layer pinctada martensi prismatic layer pinctada martensi periostracum pinctada maxima pearl layer pinctada maxima prismatic layer pinctada maxima periostracum perna viridis pearl layer d (nm) i/i0 (%) d (nm) i/i0 (%) d (nm) i/i0 (%) d (nm) i/i0 (%) d (nm) i/i0 (%) d (nm) i/i0 (%) d (nm) i/i0 (%) 0.3387 100 0.3394 79.2 0.3020 100 0.3397 100 0.3391 55.8 0.303 1 100 0.339 0 69.88 0.3264 48.8 0.3270 44.3 0.2483 12.6 0.3272 47.3 0.3266 30.3 0.248 8 12.1 0.326 8 37.01 0.3018 5.76 0.3026 13.5 0.2274 13.8 0.2702 65.7 0.2697 100 0.227 9 14.5 0.269 7 100 0.2695 77.4 0.2699 100 0.2084 13.7 0.2483 39.2 0.2481 32.8 0.208 9 11.8 0.248 1 38.47 0.2368 51.6 0.2371 47.2 0.1904 13.8 0.2373 46.4 0.2369 43.8 0.190 9 15.4 0.236 9 44.8 0.1972 46.3 0.1975 38,9 0.1867 13,7 0.1976 51.7 0.1973 27.3 0.187 1 12.9 0.197 3 34.58 www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 16 published by scholink inc. table 2. continued table 1 perna viridis prismatic layer perna viridis periostracum pinna atropurpurea pearl layer pinna atropurpurea prismatic layer pinna atropurpurea periostracum hyriopsis cumingii full shell cristaria plicata inner middle layer d (nm) i/i0 (%) d (nm) i/i0 (%) d (nm) i/i0 (%) d (nm) i/i0 (%) d (nm) i/i0 (%) d (nm) i/i0 (%) d (nm) i/i0 (%) 0.3392 100 0.340 1 100 0.3402 58.81 0.3854 12.33 0.3028 100 0.3401 61.1 0.3400 65.4 0.3269 58.06 0.327 6 66.98 0.2876 39.16 0.3034 100 0.2486 13.78 0.3277 34. 1 0.2874 39.6 0.2699 70.44 0.270 5 55.07 0.2706 100 0.2282 17.01 0.2277 14.59 0.2704 100 0.2703 100 0.2370 52.06 0.248 6 43.17 0.2487 41.81 0.2091 14.37 0.2087 13.67 0.2374 36,3 0.2484 38.6 0.1975 50.07 0.197 8 60.89 0.2375 36.58 0.1910 19.1 0.1908 21.35 0,1977 37.2 0.2373 40.3 0.1877 36.22 0.188 0 42.76 0.1978 37.13 0.1873 16.45 0.1870 16.51 0.1743 35,2 0,1977 40,6 www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 17 published by scholink inc. table 3. continued table 2 cristaria plicata periostracum ostrea rivularis inner layer ostrea rivularis loose part ostrea rivularis lower shell surface ostrea rivularis upper shell surface prismatic pearl powder prismatic pearl inner surface layer d (nm) i/i0 (%) d (nm) i/i0 (%) d (nm) i/i0 (%) d (nm) i/i0 (%) d (nm) i/i0 (%) d (nm) i/i0 (%) d (nm) i/i0 (%) 0.3421 100 0.3032 100 0.3831 8.9 0.3032 100 0.303 1 100 0.340 2 95.03 0.2755 20.33 0.3295 54.3 0.2491 5.5 0.3019 100 0.2491 11.2 0.249 0 10.3 0.327 8 50.40 0.2716 100 0.2716 83.3 0.2281 10.1 0.2274 14.8 0.2281 16.8 0.228 0 15 0.270 8 100.00 0.2499 19.89 0.2495 43.1 0.2091 6.9 0.2085 11.4 0.2091 12.3 0.209 0 13 0.248 6 35.94 0.2383 19.36 0..238 3 42.8 0.1909 24.4 0.1904 17.7 0.1909 20.0 0.190 9 20.7 0.237 8 40.89 0.1822 16.97 0.1983 77.7 0.1873 14.3 0.1868 17.4 0.1872 17.6 0.187 2 17.4 0.2335 22.42 0.1751 41.15 www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 18 published by scholink inc. table 4. shell x-ray diffraction data schistodesmus sp. prismatic layer schistodesmus lampreyanus prismatic layer unio douglasiae pearl layer unio douglasiae periostracum layer lamprotula sp. pearl layer lamprotula sp. prismatic layer lamprotula sp. periostracum layer modern lamprotula sp.pearl nuclei d nm i/i0% d nm i/i0% d nm i/i0% d nm i/i0% d nm i/i0% d nm i/i0% d nm i/i0% d nm i/i0% 0.3400 91.4 0.3398 73.2 0.3399 66.6 0.3397 100 0.3399 58.9 0.340 1 100 0.3397 100 0.3395 53.9 0.3275 48.4 0.3274 43.6 0.3275 35 0.3274 51.6 0.3274 31.3 0.327 7 51 0.3274 51 0.3273 31.9 0.2702 100 0.2702 100 0.3038 1.64 0.2700 63.2 0.2702 100 0.303 4 2.6 0.3024 1.9 0.2700 100 0.2484 52.9 0.2484 42.9 0.2702 100 0.2483 38.3 0.2484 37.3 0.270 3 61 0.2482 31.4 0.2483 32.9 0.2373 55.4 0.2373 46.9 0.2484 40.4 0.2371 37.6 0.2373 40.3 0.237 3 39.8 0.2338 35 0.2371 31.6 0.1977 52.9 0.1976 39.5 0.2373 41.2 0.1976 61 0.1976 29.4 0.197 7 64.8 0.1976 76.3 0.1976 31.9 table 5. continue table 4 trapezium liratum periostracum layer potamacor bula laevis periostracum layer corbicula fluminea prismatic layer corbicula fluminea periostracum layer modern corbicula fluminea prismatic layer corbicula maxima pearl layer corbicula maxima prismatic layer corbicula maxima periostracum layer d nm i/i0% dnm i/i0 % d nm i/i0 % d nm i/i0 % d nm i/i0 % d nm i/i0 % d nm i/i0 % d nm i/i0 % 0.3418 100.00 0.2885 23.50 0.3404 31.86 0.4249 17.42 0.3632 3.21 0.2875 100.0 0.2879 10.97 0.3399 90.81 0.3370 70.20 0.2725 76.00 0.3282 15.23 0.3336 100.0 0.3409 100.0 0.2706 58.06 0.2709 100.00 0.3279 54.75 0.2121 13.89 0.2705 100.00 0.2706 100.0 0.3033 8.71 0.3285 50.6 0.1744 2.09 0.2492 16.96 0.2703 54.46 0.1989 78.70 0.2488 49.58 0.2491 31.42 0.2697 67.10 0.2709 94 0.1438 5.77 0.2378 27.43 0.2377 56.42 0.1890 59.93 0.2375 54.28 0.2377 51.42 0.2485 30.65 0.2377 53.6 0.1415 32.81 0.2334 13.13 0.1980 100.0 0.1824 56.00 0.2332 25.17 0.2332 22.73 0.2282 7.26 0.1980 52.4 0.1361 3.21 0.1747 42.95 0.1883 50.92 www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 19 published by scholink inc. table 6. relative aragonite content of calcite in ancient and modern shells the content of calcite relative aragonite in ancient shells is less than 2%, which is negligible schistodesmus sp. shell prismatic layer 0% lamprotula hazinic shell prismatic layer 0.23% corbicula fluminea shell periostracum layer 0.78% schistodesmus lampreyanus shell prismatic layer 0% lamprotula hazinic shell prismatic layer 0.17% corbicula maxima shell pearl layer 0% unio douglasiae shell pearl layer 0.15% trapezium liratum shell periostracum layer 0% corbicula maxima shell mprismatic layer 0% unio douglasiae shell periostracum layer 0% potamacor bula laevis shell periostracum layer 0% corbicula maxima shell periostracum layer 0% lamprotula hazinic shell pearl layer 0% corbicula fluminea shell prismatic layer 0% calcite relative aragonite content in modern shells pinctada martensi shell periostracum layer 100% calcite pinctada chemnitzi shelll periostracum layer 100% calcite haliotis diversicolor shell 8.3% pinctada maxima shell periostracum layer 100% calcite ostrea rivularis gould shell most of the majority 100% calcite nerita albicilla shell 14% pteria (magnavicula) penguin shell periostracum layer 100% calcite pinna atropurpurea sowerby shell prismatic layer 100% calcite mytilus edulis shell 22% pinctada margaritifera shell periostracum layer 100% calcite pinna atropurpurea sowerby shell periostracum layer 100%c alcite chama dunker shell 15% pinctada nigra shell periostracum layer 100% calcite spondylus nicobaricus shell 8.5% abra profundorum shell 19% www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 20 published by scholink inc. position [°2theta] (copper (cu)) 10 20 30 40 50 60 70 counts 0 1000 2000 3000 4000 scsmbc007426 nc position [°2theta] (copper (cu)) 10 20 30 40 50 60 70 counts 0 1000 2000 3000 scsmbc007426 zc position [°2theta] (copper (cu)) 10 20 30 40 50 60 70 counts 0 200 400 600 800 scsmbc007426 wc corbicula maxima x-ray diffraction pattern: figure 1. pearl layer. figure 2. prismatic layer. figure 3. periostracum layer 3. research conclusion 3.1 the “outline of conchology” believes that it is correct that the nacreous layer of the shell is aragonite structure, but the peral layer of the oyster shell and the black shiny nacreous layer of the purple cracker are calcite structure. 3.2 the “outline of conchology” believes that it is wrong that the prismatic layer of shell is calcite structure. at present, only the prismatic layer of oyster shell and purple cracked jade is calcite structure, and the prismatic layer of other shells is aragonite structure. 3.3 the “outline of conchology” believes: that the stratum corneum of a shell is composed of only conchiolin. this theory is flawed. most of them have calcite structure, and a few have aragonite structure! www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 21 published by scholink inc. 3.4 shinjiro kobayashi, a japanese scholar, proposed in 1959 that prismatic pearls have a calcite structure in his “pearl research”. why does prismatic pearls lack luster? because its nacreous thickness is a=0.384 millimeters, the normal nacreous thickness is b=0.613 millimeters (thicker nacreous layers can reach 0.92 millimeters or more), with many fewer layers, resulting in a lack of birefringence effect, resulting in a lack of pearl luster and oil luster. it also causes the pearl nucleus to have strong reflection light, and after interference, it appears earthy yellow. this is the reason why prismatic pearls lack pearl luster. 3.5 from the x-ray spectra of the corbiculidae, corbicula maxima pearl layer, prism layer, and keratin layer of the clam shell buried in the ground for thousands of years, it can be seen that the structure of aragonite is developing towards a higher degree of crystallization-“single crystal”, indicating that the aragonite grains are getting larger and more stable over time. 3.6 modern shells contain some calcite, but ancient shells have almost no calcite. after a long period of time, calcite has turned into aragonite in shells! the records in geological crystallography books and textbooks are incorrect. 3.7 other ancient shells besides the corbicula maxima shells also have changes in decreasing, narrowing, and strengthening spectral lines over time. however, shells that are too thin and not completely layered are easily affected by the stratum corneum. it is better to use thicker shells for detection! 3.8 the rest of the ancient shells are small and not easily stratified 3.9 x-ray diffraction from the prismatic layers of ancient shells once again confirms that the prismatic layers of shells are all aragonite structures. funding 90 year old commemorative works iii fund project “artificial growth of aragonite crystals and artificial development of pearls” chen guiqing, chen junhao 1985 (approval no. 85084). fund project “research on the structure and imaging mechanism of artificial pearl cores and artistic image pearls” chen guiqing, chen junhao 1989 (approval number 890xx). www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 22 published by scholink inc. references chen, g. q., & chen, j. h. (2017). new conclusion on the crystal structure of pearls and shells. journal of applied oceanography, 36(4). chen, g. q., chen, j. h., & chen, p. (1986). a study on the natural pearls and shells of pinctada martensii. marine medicine, 1986(3), 4-7. chen, g. q., chen, j. h., & zhang, x. j. (1985). x-ray diffraction study on the shell of jinjiang oyster. marine medicine, 1985(3), 4-6. chen, j. h., & chen, g. q. (2018). crystal structure and application exploration of pearls and shellfish. jinan university press. chen, j. h., & chen, g. q. (2019). the ancient shells were sdudied by x-ray diffraction and electron probes. journal of water resources and ocean science, 8(6), 86. https://doi.org/10.11648/j.wros.20190806.11 kaiichi, m. (1965). zhenzhu chronicle, beilongguan. kobayashi, s., & watanabe, t. (1961). research on pearls 169-176. technical hall. rock and mineral research office, department of geology, nanjing university. (1978). crystallography and mineralogy. beijing: geological publishing house. zhang, x., & qi, z. y. (1961). outline of conchology. science press. zhao, s. r. (ed.). crystallography and mineralogy (p. 412). geological publishing house. curriculum textbooks for higher education in the 21st century. https://doi.org/10.11648/j.wros.20190806.11 energy and earth science vol. 3, no. 2, 2020 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 49 original paper from renewable energy to renewable fuel: a sustainable hydrogen production rafiq mulla 1 & charles w. dunnill 1* 1 energy safety research institute, swansea university, bay campus, fabian way, sa1 8en, uk * charles w. dunnill, e-mail: c.dunnill@swansea.ac.uk received: july 17, 2020 accepted: july 31, 2020 online published: september 16, 2020 doi:10.22158/ees.v3n2p49 url: http://dx.doi.org/10.22158/ees.v3n2p49 abstract hydrogen, a zero-emission fuel and the universal energy vector, can be easily produced from many different energy sources. it is a storable, transportable product that can be used on demand to overcome supply and demand imbalances. as of today, most of the hydrogen produced comes from natural gas; the production process itself is in fact not so pollution free. as the world is looking for a low carbon future, researchers have therefore been looking for more sustainable, environmentally friendly pathways of hydrogen production by using renewable energy sources such as solar and wind. among the different methods, water electrolysis is a conventional and promising method of hydrogen production if renewable energy sources are to be employed in the process. lots of progress has been made over the past few years in extending the use of hydrogen in different sectors. this perspective article briefly covers the recent developments in the hydrogen fuel-based projects and technologies and provides a description of the advantages of employing renewable energy sources for sustainable hydrogen production. keywords hydrogen, renewable energy, electrolysis, thermoelectric, zero emission, sustainable production 1. introduction renewable energy sources (solar and wind etc.) will be the fastest-growing power sources for electricity generation in the near future. these intermittent sources, however, suffer from supply and demand imbalances (jones, al-masry et al., 2018; quarton, tlili et al., 2020), as there is no correlation between say the strength of the wind or the position of the sun in the sky and the consumers desire for electricity. at low levels this is not too much of an issue, but as the percentage mix increases this will become an increasingly important topic. balancing this supply and demand is developing into one of www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 50 published by scholink inc. the biggest challenges facing energy scientists around the globe. much work is currently underway, correlating the supply with demand producing “smart systems” however there is an alternative which is to decouple supply from demand using a university energy vector. the storage of energy in the form of hydrogen is just such a possible energy vector. all forms of energy can easily and relatively efficiently be converted into hydrogen and all forms of power can be utilized from the hydrogen; electricity and heat via fuel cells or heat from combustion, either 100% pure or as a enrichment to natural gas (jones, al-masry et al., 2018). once produced, hydrogen can be stored for unimaginable lengths of time thus decoupling supply from demand. as long as there is storage capacity and the demand does not exceed the supply, the inherently “smart” system will balance itself out, even with a 100% renewable intermittent input. figure 1. the number of micro-chp systems installed to date (solid lines) and near-term projections (dotted lines) for residential use (yoy stands for year-over-year). reproduced from (staffell, scamman et al., 2019) published by the royal society of chemistry the implementation of hydrogen-fuel based technologies is growing rapidly all over the world to cut the burning of fossil fuels wherever possible. japan has been working towards a hydrogen society to reduce environmental burdens and revitalize regional economies by extending its use by (i) promoting fuel cell electric vehicles (fcevs), (ii) increasing hydrogen production, and (iii) introducing fuel cells for residential applications (energy 2014; staffell, scamman et al., 2019). it is also envisioning to establish a carbon-free hydrogen supply by 2040 (metd 2017; staffell, scamman et al., 2019). japan has deployed a large number of residential fuel cell systems (micro-chp) and is one of the leading countries in the world in implementing hydrogen technologies for daily uses (micro-chp technology: micro combined heat and power, is a technology that generates heat and electricity from the same www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 51 published by scholink inc. energy source, and the fuel cell is a device that converts the chemical energy of a fuel (hydrogen) into electricity). recently, many european (eu) countries are beginning to promote hydrogen as a fuel in different fields; it is also being introduced for automobile industries as new techniques to store hydrogen in liquefied form have been developed and found to be successful on primary testing which is crucial to implement the technology for small vehicles such as scooters (fcw 2020). figure 1 illustrates the contribution of major countries in implementing micro-chp technology for residential use. the extension of hydrogen usage to automobile industry will improve air quality as vehicles’ contribution to the co2 emission is very high and ever increasing. similarly, france has launched a hydrogen project; hydrogen is produced from the renewable energy and will be stored and transported in the natural gas grid which flows in pipes under the streets of a village, aiming to energize hundreds of homes (engie 2016). this year, scotland is also planning for its first ever hydrogen-powered homes; as a part of a pilot scheme (sampson, 2020), a few homes will be incorporated with micro-chp fuel cell technology. interestingly, hydrogen can also be burnt as a flame or catalytically (du preez, jones et al., 2019; du preez, jones et al., 2020). when hydrogen burns, it produces no toxic/greenhouse gases but water (figure 2), therefore, a 100% clean energy pathways can be created using production methods powered by renewable energy sources. at present most of the hydrogen is produced from steam reformation of fossil fuels, so called brown hydrogen and hence even hydrogen is also indirectly responsible for carbon emissions. this can be avoided or minimized by sequestering the carbon dioxide (blue hydrogen, or by electrolyzing water using renewable energy such as excess wind; implementation of these clean methods is already under progress that releases virtually zero greenhouse gas to the environment. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 52 published by scholink inc. figure 2. an illustration showing h2 burning produces no greenhouse gases 2. hydrogen production from renewable sources a direct and promising method to generate green hydrogen is found to be water electrolysis: a process of splitting water into hydrogen and oxygen using electricity (gannon, warwick et al., 2020). a simple two electrode (anode and cathode) unit called an electrolyzer (usually, it consists of three parts: electrodes, separators/membranes, and electrolyte) is used for the purpose (mulla & dunnill, 2019). there are three types of electrolyzer designs such as (i) alkaline electrolysis cells (aec), (ii) proton exchange membrane electrolysis cells (pemec), and (iii) solid oxide electrolysis cells (soec) of which aecs have been in use in various industries as they have simple designs and can be built at a relatively low capital cost and are durable (passas & dunnill, 2015; phillips & dunnill, 2016; phillips, edwards et al., 2017; mulla & dunnill, 2019). to start electrolysis process, a dc electric supply is passed through an electrolytic solution, splitting water (h2o) into its component parts (hydrogen (h2) & oxygen (o2)) where h2 being generated on the cathode and o2 on the anode (figure 3). the decomposition of h2o into h2 and o2 happens due to the application of electric voltage which forces ions to undergo either oxidation or reduction at the electrodes, the mechanism can be expressed as follows: .................. (1) www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 53 published by scholink inc. figure 3. a schematic of a simple electrolyzer for hydrogen production through electrolysis in general, the efficiency of water splitting is determined by the amount of electrical energy used to generate an amount of hydrogen, can be defined as follows (phillips & dunnill, 2016; phillips, edwards et al., 2017; mulla & dunnill, 2019): ....................... (2) where the term “energy output” refers to the amount of hydrogen produced and “total energy input” is in general refers to the total electrical energy consumed in the production. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 54 published by scholink inc. figure 4. water electrolysis powered by renewable energy for hydrogen production as illustrated by figure 4, the required electrical energy can be provided by different renewable energy sources such as wind turbine, photovoltaic (solar panels), and also from solar thermoelectric generators (steg). wind turbine and photovoltaic systems are already well-known, successfully working on a large scale in different sectors, and are also recently being linked to hydrogen production units. both the energy sources appear to be promising for water splitting according to recent developments; alongside, research on coupling stegs to the electrolysis is also under progress (baranowski, snyder et al., 2012). industrial waste heat is a fantastic source of cheap energy that can be utilized for hydrogen production (mulla & dunnill, 2019). thermoelectric generators work on the principle of seebeck effect, in which a temperature gradient applied across the device produces useful electric potential. stegs generate electricity from concentrated sunlight; solar radiation is used as a source of heat to develop temperature gradient across the device. larger temperature gradients across the generators can be achieved by using solar concentrators/lenses which result in better output power www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 55 published by scholink inc. density from the generator. the conversion efficiency (η) of the thermoelectric generators can be estimated using the following standard equation: ..................... (3) where zt is the thermoelectric figure of merit of the materials used in the generator, tc and th are the cold and hot side temperatures of the generators. therefore, a large temperature difference across the generator designed with good thermoelectric materials (i.e., materials with high zt value) is important to generate a decent electric power. up to 15-30% efficiency is predicted from these stegs when thermoelectric materials of zt > 2 are used in the generators (baranowski, snyder et al., 2012). 3. challenges and opportunities currently, most of the hydrogen is generated from fossil fuels as they provide more economical methods over electrolytic water splitting. this production method, however, is unsuitable for a low carbon future. presently, the largest consumers of hydrogen (produced by fossil fuels) are chemical industries where nearly half of hydrogen is used in ammonia production; it alone causes about 1% of total global greenhouse gases emission (boerner, 2019). in the meantime, as the world is looking for a low carbon future, there is an increasing demand for renewable sources, shortly; they may become available at competitive prices. by utilizing clean nature of hydrogen, blending it with biogas (mehr, moharramian et al., 2020), implementing hydrogen injection in coal-dominated regions (wang, klemeš et al., 2020), etc can help reduction of co2 emission. hydrogen can be safely mixed in small quantities with natural gas depending on the end-use appliances. countries like germany and the netherlands have 10-12% (by volume) blending levels (staffell, scamman et al., 2019). the advantage of hydrogen blending can be seen from the data in figure 5 that shows the relationship between energy content and carbon savings with respect to hydrogen injection mixtures (staffell, scamman et al., 2019). so, about 20% hydrogen (by volume) blend would give 13 gco2 per kwh carbon emissions savings. however, at present, higher blending is not possible due to technical and administrative constraints (staffell, scamman et al., 2019). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 56 published by scholink inc. figure 5. the relationship between energy content and carbon savings with respect hydrogen injection mixtures. reproduced from (staffell, scamman et al., 2019) published by the royal society of chemistry the low efficiency of the thermoelectric generators is a major drawback to be used independently in the production of hydrogen, and therefore they can be used as a supplementary source by coupling with photovoltaic to improve overall efficiency or production rate (mulla & dunnill, 2019). at present, the commercial thermoelectric generators are mainly contained materials like bi2te3 and pbte which makes them quite expensive, and also the elements like tellurium (te) are highly toxic and scarce hence, a large-scale implementation facing difficulties (mulla & dunnill, 2019; mulla & rabinal, 2019). nevertheless, rigorous scientific investigations are under progress which produced many new, low-cost and non-toxic materials and improvements can be realized in the near future (mulla & rabinal, 2018; mulla & dunnill, 2019). the efficiency argument however does need to be taken in context as the use of otherwise wasted heat yields green value from waste (mulla & dunnill, 2019) and is economically viable even with low efficiency, especially if the teg can be produced cheaply (mulla & rabinal, 2018; mulla & dunnill, 2020; mulla, jones et al., 2020). there are also other methods to generate hydrogen from solar energy such as photoelectrochemical (pec) water splitting which also offers a promising approach for hydrogen production; however, requires scalable pec cells in addition to the stable and efficient photoelectrodes (landman, halabi et al., 2020). another drawback of this method is associated with the collection of hydrogen gas from www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 57 published by scholink inc. millions of pec cells (landman, halabi et al., 2020). therefore, large-scale pec water splitting under sunlight is yet to be demonstrated. similarly, studies are under progress on improving photocatalytic hydrogen production using different and new photocatalyst materials and also on the use of photocathode materials (warwick, barreca et al., 2015; crespo-quesada, pazos-outón et al., 2016; kuehnel & reisner, 2018; ghosh, nakada et al., 2020). although producing hydrogen from electrolysis is currently dominated by the cost of electricity, the capital cost of electrolyzer will become important in the future when electricity generated from renewable energy becomes abundant and cheap (esposito, 2017). the recent cost reductions of wind and solar power enable new opportunities for a competitive hydrogen production. in such scenario, the cost of electricity could be around $ 30/mwh (as estimated by wind farms in morocco and solar plants in chile and dubai) and it is predicted that hydrogen production cost would not exceed $ 2/kg (philibert, 2017). research priorities with regard to electrolysers include reducing the capital cost of the electrolyzer units, operation life, improving their designs, and efficiency (phillips & dunnill, 2016). typically, in basic design of an electrolyzer, the two electrodes are separated by a liquid electrolyte, which hinders the charge flow and results in low current densities. so, efforts on improving electrolyzer cell designs are going on and new design concepts like “zero gap cell” are under investigation where the charges can move much easier than in the basic cell design (phillips & dunnill, 2016). similarly, research interest in membraneless electrolyzers is increasing to reduce the cost of the units (esposito, 2017). further, when there is excess electricity available from windmills, instead of curtailing, it can be used to generate hydrogen which can be stored for the future and it could be integrated with electric power at a wind farm for better supply-demand flexibility (perni, liu et al., 2008; cloete & hirth, 2020). in addition, offshore renewable energy resources also have a great potential to contribute to the sustainable hydrogen production (gondal, 2019). overall, there are numerous opportunities to firmly establish a clean production technology for hydrogen production from renewable sources. 4. conclusions hydrogen can be used in a wide range of applications and the hydrogen-powered fuel cells could power our vehicles, replacing the fossil fuels used in most vehicles today. in order to achieve a clean future, the use of hydrogen must be extended. clean production of hydrogen, therefore, is essential to reduce greenhouse gas emissions. with the help of wind and solar powers, sustainable production of hydrogen can be achieved. acknowledgments authors are thankful to the welsh government (eu european regional development fund) for funding the rice (reducing industrial carbon emission) project (grant number: 81435). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 58 published by scholink inc. conflicts of interest there are no conflicts of interest to declare. references baranowski, l. l., snyder, g. j., & toberer, e. s. 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(2015). pt-functionalized fe2o3 photoanodes for solar water splitting: the role of hematite nano-organization and the platinum redox state. physical chemistry chemical physics, 17(19), 12899-12907. https://doi.org/10.1039/c5cp01636c https://doi.org/10.1039/c6ra22242k https://doi.org/10.1039/c6ra22242k https://doi.org/10.1016/j.ijhydene.2017.07.184 https://doi.org/10.1039/c9se00833k https://doi.org/10.1039/c8ee01157e https://doi.org/10.1016/j.energy.2020.117565 https://doi.org/10.1039/c5cp01636c energy and earth science vol. 3, no. 2, 2020 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 61 original paper lion mountain landslide in non-urbanized terrain: changing the myth of landslide occurrence in western sierra leone yusuf a. lahai 1 , dauda m. kamara 2 & chernoh m. jalloh 1 1 department of geology, fourah bay college, university of sierra leone, freetown, sierra leone 2 school of environmental science and engineering, suzhou university of science and technology, suzhou, china * yusuf a. lahai, department of geology, fourah bay college, university of sierra leone, freetown, sierra leone received: june 25, 2020 accepted: july 8, 2020 online published: september 20, 2020 doi:10.22158/ees.v3n2p61 url: http://dx.doi.org/10.22158/ees.v3n2p61 abstract freetown has documented one of the most devastating landslides in the world in 2017. many debates in the media, few scientific papers and technical documents, have argued with eloquence ascertaining human factors, particularly deforestation and urbanization, as the dominant causative factor. this notion seems to be widely accepted for all other slides by the communities, government agencies and departments. therefore, this work attempts to expand on existing public knowledge by demonstrating the less influential or insignificant human factors which can have impacts on certain landslide occurrences in the freetown layered-complex. the representative landslide considered for this study occurred beyond the vicinity of urbanized zone. therefore, to establish a clear understanding of the actual causative factors, fieldwork and laboratory investigations were undertaken. during the field survey, we assessed the rock type, discontinuities, geomorphology and hydrological influence of the landslide. the specific rock series underlying the landslide was confirmed through thin section analysis at the national minerals agency (nma). dcp tests and laboratory analyses enhanced the derivation of geotechnical properties of the residual soil/regolith. this work systematically presented how natural conditions, such as: geology (rock types and tectonic signatures), geomorphology, hydrology and the geotechnical properties of the slope soil, have interplayed in the occurrence of the landslide event. in addition, the slip surface of the landslide occurred at a depth below the reach of plant activities (2.6 m). this information may help modify public messages by institutions and can be a source of useful information for the country’s landslide www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 62 published by scholink inc. disaster management department (ldmd). keywords dynamic cone penetration, geotechnical properties, human factors natural conditions 1. background of the study freetown is located in the western area of sierra leone, which sits on the edge of the atlantic ocean in west africa. rapid population growth in this region became eminent during the civil war (especially from 1999 to 2001) because of its insulated nature against rebel activities. economist intelligence unit (2002) and kaldor and vincent (2006) mentioned that onethird of the country‟s 2.6 million displaced persons and 500,000 farm families relocated to the safe haven (western area) (gbanie et al., 2015). this has accounted for the rising population in freetown (weekes & bah, 2017; sesay et al., 2006; gogra et al., 2010) amounting to enormous pressure on the small space between the mountains and the sea. the unavailability and affordability of suitable lands at coastal and inland settlements, have forced many people to settle on steep hills/mountains of the city. over time, their migration to those terrains, has facilitated rapid encroachment into vital forestlands (once-protected forest highland) without any adherence to land policies and laws. as a consequence, the uncontrolled urban developments have caused several environmental issues, ranging from pronounced changes in natural channels from a significant increase in the storm water run-off and erosion (undp & epa, 2017), to over-harvesting of timbers on the hillsides, leading to deforestation, and eventually causing soil erosion. in effect, these intense anthropogenic activities, mainly deforestation and urbanization, have contributed to landslide occurrences in the freetown-layered complex, which are captured in few available documents/articles (e.g., munro, 2009; undp & epa, 2017; cui et al., 2019) as the dominant causal factors for the regent rainfall-triggered landslide. this information on causal factors seems to be a widely accepted phenomenon for any landslide event within the complex irrespective of the terrain/zone of occurrence, indicating an absolute dearth in knowledge regarding landslide causal factors. this necessitates scientific investigation of landslide occurrences in areas unaffected by deforestation and urbanization. historically, landslide events have occurred in forested area (redshaw et al., 2019), including an area formally designated as the western area peninsula forest (sesay, 2005). recent landslide inventory conducted through field surveys and the exploration of google earth satellite images (-accessed in 2019 and 2020) in the area represented by figure 1, has shown greater percentage of landslide scars in forested area than the urbanized zones (lahai, 2020). the landslide used as a case study affected the lion mountain located 938m northeast of fula town community; hence, the name lion mountain landslide is adopted in this paper. it is a non-urbanized terrain: an area that is sparsely vegetated, but enough to preserve its beneficial action in terms of mechanical (root anchoring) and hydrological (suction generated by root water uptake) effects (balzano et al., 2019). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 63 published by scholink inc. landslides have caused numerous destructions to forest in many parts of the world, and are seen to affect hugely the tropical areas due to the combination of intense rainfall and earthquakes. studies done by garwood et al. (1979); martinez et al. (1995); schuster and highland (2007) have demonstrated elsewhere where the above triggering factors existed (i.e., rainfall and earthquakes). similarly, the study area belongs to the tropical climate, which has a characteristic heavy rainfall, but the seismic hazard level in the entire country is very low and landslides triggered by earthquakes would be extremely unlikely within a 50year return period (arup et al., 2018). this makes the case unique, indicating strong relationship with geological instability and other geoenvironmental factors, which this study seeks to unravel. furthermore, no attempt has been made to investigate landslide occurrence in non-urbanized areas and by extension the effects on its biodiversity. the few studies focused on landslide occurrences within the urban areas and specifically on regent landslide (e.g., undp & epa, 2017; arup et al., 2018; cui et al., 2019; redshaw et al., 2019; lahai et al., 2019): which has accounted for the worst fatality in the country and the world during the year of occurrence, madina landslide (e.g., sillah et al., 2011; lahai et al., 2020), and charlotte landslide (lahai et al., 2020). information pertinent to these slides is not adequate and as such lacks the realistic basis to be extrapolated to other areas affected by landslides within the freetown-layered complex, particularly in forested areas where little or no human activities are not experienced. this constraint in knowledge extension to other areas could be due to marked lithologic, topographic, hydrologic and tectonic variation across the terrain. therefore, this work provides a comprehensive and better understanding of the actual causes of the lion mountain landslide through the following approaches: an intensive field assessment of the slide, laboratory analyses on soil samples, soil strength determination using dynamic cone penetration (dcp) and data analyses obtained from the united states geological surveys (usgs) pertinent to the landslide location and its surroundings. this work presents detailed and accurate information on the geology, hydrology, geomorphic and geotechnical properties of the residual soil/regolith of the landslide. this is a significantly generated scientific fact on the conditions responsible for landslides in non-urbanized zones (forested areas). the information is hoped to eliminate knowledge gap and change the general notion on landslide causative factors, which will support the modification of public documents and government policies. 2. description of landslide area the area falls in the northwestern part of freetown, which is located 0.93km northeast of fula town (8.430708n, 13.243174w) and 1.12km southwest of the regent landslide. the geographic coordinates (latitude and longitude) of the landslide is recorded as 8.417325n and 13.230336w, which falls within the non-urbanized zone (forested area). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 64 published by scholink inc. figure 1. location of lion moutain landslide (a) map showing the two landslides and area of interest (source: google earth-accessed 2020), (b) freetown map with inset of interested area encompassing zone 1, 2 and 3 of the complex the area consists of mountain ranges trending from nne to ssw direction, which are separated by fault planes (they are seen as stream valleys, representing an area of discharge) as observed in figure 1.the landslide seems to have affected one of these mountainous slopes/faces (wsw) of the freetown peninsula. they have a vegetation cover ranging from thick to sparse forest, with patches of barelands (exposed rocks and soil), which represent landslide scars (figure 2). figure 2. location of landslide scar in relationship to bareland, sparse forest and thick forest reserve www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 65 published by scholink inc. like any other locality in west african country, the landslide area experiences tropical and humid type of climate that is strongly controlled by the tropical air mass blowing the entire sub region. unfortunately, there is an absence of an accurate rainfall time-series data representing freetown, which may prevent the determination of location-specific values (redshaw et al., 2019), but analyses on data obtained from the country‟s meteorological agency present a general understanding of how rainfall conditions lead to both flooding and landslides. from the analyses, high amount of precipitation (100mm-1200mm) are received from july to september. this landslide event is reported to have taken place within this time bracket (especically august, 2018), and there has been a confirmed information on backward extension of the landslide head wall during the rains in 2019. 3. methodology 3.1 field work this survey was undertaken in march 2020,which coincided with the dry season, and included field assessment of the landslide with keen interest on the underlying geology, tectonic structures (fractures and joint sets), surface and subsurface hydrology and its geomorphology. the dynamic cone penetration (dcp) was used to conduct in-situ soil (regolith) test. only three tests at random intervals along the slope were undertaken to give an insight into the overall slope cover (residual soil) strength. this assumption is connected to the homogeneity of the underlying rocks (same chemical and physical composition) and also number of dcp blows (ndcp) per penetration depth plots for the three testing points show high consistency (coefficient of variance is less than 30%). additionally, recording of vital information pertinent to the landslide (point coordinates of the landslide, landslide area, perimeter, length, width and slide volume) was achieved, and finally, description and classification of the slide done in accordance with varnes (1978) and cruden and varnes (1996). extraction and measurement of parameters (landslide‟s point coordinates, area and perimeter) from google earth image corresponded with field data obtained using the global positioning system (gps). information on the landslide‟s occurrence times and activities was derived from interviews with nearby local people who often visit the area for wood fetching prior the incident. rock samples were logged using field-based approach (field description). the discontinuities (layering, fracture/crack and joints) on the landslide main body and adjacent surfaces were identified, their attitudes (strike and dip) measured using the silva compass and clinometer and recorded appropriately. other parameters noted include: diameter of boulders, thickness of bouldery debris, and slide volume. both rock and soil samples were later collected for thin section analysis and for geotechnical soil investigation at the national minerals agency‟s laboratory and the sierra leone road authority (slra) materials laboratory respectively. hydrologically, we also assessed the bottom slope and nearby darinage system (current river and streams) that may have affected the landslide or affected by the landslide materials in addition to the lineaments on post landslide surfaces (evidence of groundwater source); which provide clue to hillslope www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 66 published by scholink inc. hydrology and flow path during the rains. key parameters noted were: the flow direction, proximity to landslide site and any erosive evidence on the stream bed. extraction of these hydrological elements including drainage density of the landslide area and environs represented by the inset in figure 1(b) were derived from the digital elevation model (dem). finally, the landslide geomorphological elements recorded along its entire length are: elevation, degree of slope, slope aspect and they were compared with the dem for validation. 3.2 laboratory tests/analyses laboratory work was conducted on both rock (grab) and soil samples in different laboratories at nma and slra respectively. the grab sample was cut into two parts using the slab cutter. one half of the grab sample was used for the preparation of slide (30-micron thickness) for thin section analysis, and the other for xrf analysis. for the purpose of this work, the result of thin section analysis formed the basis in ascertaining the specific gabbroic series underlying the landslide. two soil samples (small and bulk) were obtained at 1.5m depth in each of the three trial pits within the landslide area for geotechnical soil investigation. the small samples were well preserved to prevent any loss of water component between the time of sampling and testing in the laboratory. these samples were used for the determination of moisture content using oven-drying method and the consistency limits of the soil. the bulk samples were utilized for the analysis of particle size distribution using the sieve method and the determination of specific gravity using 50ml or specific gravity bottle. finally, a cone cutter (used in the field) and a weight balance were used to determine the bulk density at each of the three sampling sites. 3.3 data analyses the dem data, which we obtained from the united states geological surveys (usgs) were pre-processed and the 3-d analyst tool in the gis environment utilized to generate classified maps of geomorphic factors (slope, aspect, curvature and elevation) and hydrological factors (drainage density, drainage system, flow direction). also, the location of the landslide (point coordinates) was integrated in each of the factor maps to establish it links with the terrain-specific factors, and google earth image utilized to enhance derivation of landslide dimensions that correlated with field data. finally, geotechnical data were inputed, double checked for errors in data capture, arranged, and analyzed in the microsoft excel spreadsheet. this facilitated the presentation of data in tables and graphs. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 67 published by scholink inc. 4. results 4.1 lion mountain landslide the lion mountain landslide with dimension 420m by 86.3m and a perimeter of 1,257m, is broadly translational involving rock fragments (angular and sub-rounded) and residual soil. it is a large landslide (area > 3000 m 2 ) (skrypczak et al., 2017), with a slide volume estimated as 94239.6 m 3 using the method presented by adegbe et al. (2014). the sliding took place along the interface between bedrock (resistant gabbroic rock) and the overlying soil (weaker material) at few portions along the slope (upper and mid slope in figure 2), and along discontinuities (joints and layered planes), with clear evidence at the landslide base. the failure surface is planar, which is persistent and slightly undulating at post landslide bedrock exposures. the estimated depth of rupture ranges from 2.5m to 2.9m (below the zone affected by plant roots). the boulders found at the landslide base were released either together with the debris or from the fractured rock mass. they bounced and slid along the slope to their point of deposition in the lower plain: a process refered to as boulder bounce. also a proportion of debris and large boulders formed bulge with approximate elevation of ≈0.9m in the lower plain, whilst others (mainly debris) mixed with the surface runoff water to give rise to debris-laden flow (flow-like behaviour of the landslide), which became enhanced by basal diverted streams, and carried into the major stream valley (a valley that contained a river named the lion mountain river). the total run-out is estimated as 1,273 m (1.28km), which spans from landslide headscarp to a point where the mountain lion river connects to the babadorie valley (confluence point). indigenes of the nearby community (fula town) confirmed the presence of water seepages on the slide‟s body for a couple of days following rainfalls, which could have emerged from the vertically dip fractures and joint sets. figure 3. landslide tracjectory and typology (a) translational landslide body from crown to toe, (b) debris-laden flow, (c) lion mountain landslide with implied flooding carrying medium and fine-sized particles (debris-laden flooding) www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 68 published by scholink inc. 4.2 geological, geomorphological and hydrological conditions of the landslide 4.2.1 geological conditions the landslide is underlain by a pegmatitic gabbro (very coarse-grained ultramafic rock) comprising up to 90% mafic minerals (pyroxene). the lithology is quite extensive, and belongs to zone 3 of the freetown-layered complex proposed by chalokwu (2001) and chalokwu et al. (2010). identification and analysis of specific-rock series within the freetown complex unit affecting the landslide is particularly important than determining this lithologic unit with a very general approach. this approach unravels the distinct characteristic features corresponding to compositional variation within the unit. post landslide observations revealed few fractures on the slightly undulating, but generally planar exposed fresh surfaces at the upper slide section and in the center; which are alternated by weathered and partially weathered materials along slope‟s length from top to base. they also show evidence of exfoliation joints, that could make the affected section appear to be flaking off in sheets, and linear marks (striation) indicating downslope rock sliding against each other (figure 4). but much degree of rock fracturing are visible on weathered and partially-weathered rock surfaces at slide‟s base, starting just beneath the mid rock exposure, forming joint sets (nnw-sse) to the toe (planar portion of the landslide). some of the lineeaments are parallel to the slope while others are not and most of the dips are near vertical (~90 degree). the most obvious fracture has an offset of 15mm and it is orientated in the nne-ssw direction with a vertical dip as well (figure 5). the initial sliding surface may be associated to this weaker zone, followed by detachment of regolith from the lubricated surface of the underlying fresh rock (bedrock and overlying soil interface). however, this entire process of landslide seems difficult to track in post-disaster investigation. also, the orientation of rock layering (ese-wnw) and dip (43 0 nw-almost the same as sliding plane) at the landslide site when compared with the strike and dip of outcrops on adjacent slopes and the mountain village (8.430708n, 13.243174w) showed correspondence. this aided in distinguishing in-situ rocks from boulders. the boulders with diameters ranging from 2m to 5.5m, were deposited at the bottom slope and along the stream valley underneath. they range from rounded old black surface colour weathered corestones to angular chunks released from the fractured rock mass. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 69 published by scholink inc. figure 4. local geology (a) distinct zones along slope face showing differential weathering, separated by a tranverse crack, (b) typical rock type with evidence of exfoliation joints, (c) intensely weathered landslide basal section where the slipage/failure may have initiated, (d) parallel proto-joints in the process of developing as full mechanical fractures but maintaining considerable true cohesion the constituent rock is susceptible to chemical weathering, with clearly weathered zones at the ridge top (weathering profile is estimated as 2.6 m thick) and very thin along the flanks (1.5m-2.5m). rocks at the upper landslide base are strongly affected by weathering (block weathring/rind weathering) (figure 5a), and is seemed concentrating in the fractured planes/zones, which together with upward groundwater flow and increased pore-pressure on key joints may have initiated basal failure. figure 5. (a) joint sets (vertical dip) in highly weathered pegmatitic gabbro, (b) the largest offset fracture (15mm) within the landslide area www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 70 published by scholink inc. 4.2.2 geomorphological and hydrological conditions geomorphologically, the landslide slope is cataclinal or a dip slope (i.e., topographic surface dips in the same direction and approximately by the same amount as the true dip of the underlying rock). field data on landslide elevation and slope (recorded at the main scarp) are 335m and 35 0 respectively, and the event affected west-south westerly (wsw) facing slope (slope aspect). these values correspond with those extracted from the dem, with the slope belonging to class four (4) as seen in the figure 6 below. excluding the slope aspect, elevation and slope values decrease from landslide crown to toe. figure 6. dem for geomorphic factors (a) slope aspect, (b) slope curvature, (c) slope angle www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 71 published by scholink inc. the toe is characterized by two minor streams (quick stream) separated by 0.9 m accumulated debris, which eventually may have built significantly poor drainage properties, making it prone to the development of excess pore water pressure when saturated and sheared (undrained loading). these streams emerged due to barriers to natural flow path, causing the surface water body to diverge into two channels. the diverted streams could be traced up to 100m from the landslide toe to the confluence point (point of intersection with the lion mountain stream). they may have eroded the sediments (relatively loose materials) along their paths into the lion mountain stream, but could not significantly affect the centre material (sedimentary pile). the two minor stream channels at slope base and the lion mountain valley (main stream channel controlled by north westerly striking valley)-which connects the study area drainage system to babadorie valley constitute the surface hydrology. specifically, the landslide area is drained by 1 st order streams and the entire area belongs to sixth order basin, which joins rivers and tributaries based on the topography (figure 7b). there is no evidence of effective erosional action (e.g., removal of material from the foot of the slope in the river bed by river bank erosion prior to the landslide event), which could have influenced any downslope movement. the drainage density of the slide area belongs to class three, which is moderate (19.88-2.81 km/km 2 ) and may favour groundwater recharge (figure 7a). the main channel is separated from the landslide area by a relatively flat plain that is approxmately 20m wide, which always become flooded during persistent rainfall. following the landslide event, the basal accumulated sediments extending towards the river may have been over-saturated with the flooded water leading to an increased pore pressure. this accounts for the loose nature of the materials when stepped into by nearby local people. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 72 published by scholink inc. figure 7. dem for hydrologic factors (a) drainage density (b) drainage system (c) flow direction however, evidence of water seepages/springs from open joints after rainfalls confirmed by local inhabitants of the nearby community, indicates interaction between precipitation and groundwater. the moderately and hghly weathered pegmatitic gabbro is attributed to the accumulation of the infiltrated rainfall water through the vertical joint sets (open fractures), thereby raising the groundwater level. therefore, the landslide stability would have been impacted by the upward migration of groundwater through the joints to weaken the regolith above. this hydrological principle is supported with few studies that have established the influence of upward groundwater flow on slope stability (weng et al., 2018). the groundwater in the discontinuities would also have exerted an uplift force to the rock and undermined the stability of the weak stratum and rock-soil interface. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 73 published by scholink inc. 4.3 geotechnical assessment the properties of landslide‟s underlying geology are extremely important for the propensity for landslide occurrence. the decomposed/weathered zone acts as soil considering mechanical perspective, making the determination of its geotechnical properties necessary (yalcin, 2011). this assessment was carried out using in-situ field test by dcp and laboratory tests for the purpose of evaluating the geotechnical properties of the slope cover soil (regolith). the dcp probed or revealed information on the thickness of weathered soil cover (depth > 1.5m) and its bearing strength. the strength factor, which according to undp & epa (2017) was not considered by the affected populations at regent prior construction in supposedly a non built-up areas. however, results of dcp tests presented in figure 8 show variation in soil bearing strength with depth along the soil profile, which generally decrease towards the bed rock. the average number of dcp blows (ndcp) plot also varies with depth and shows strong correlation with the weak to moderate gabbroic layering. this method evaluated the susceptibility of the bottom soil layer that slipped down the slope and extrapolated the potetial effects of overloading (e.g., precipitation/rainfall, infrastructures, sediment piling and dam) on landslide occurrence (i.e., implied anthropogenic impacts). figure 8. variation of average bearing strength capacity and ndcp in the soil profile overlying the bed rock. uba: ultimate bearing capacity, abc: allowable bearing capacity and ndcp. number of dcp blows www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 74 published by scholink inc. the second part of the geotechnical assessment involves the determination of natural moisture content, specific gravity (g), grain size distributions consistency limits (plasticlimit, liquid limit and plasticity index), and liquidity index (li) of the landslide soil. results of these parameters are presented in table 1. the soil moisture content is within range, average specific gravity estimated as 2.41, which is below the specific gravity of the fresh rock sample (2.8). the soil is well-graded, which have been grouped into three divisions corresponding to the major constituents. they include: gravel, sand and fines (clay and silt), with the fines exceeding the gravel component. the fine fraction can affect permeability and enhance pore pressure following periods of persistent rainfall. with the absence of x-ray diffraction (xrd) facility in the country to identify and determine clay fraction, analysis at the british geological survey (bgs) laboratories in nottingham on regent bulk debris samples, presented by redshaw et al. (2019), has given an insight into the probable clay mineral type called halloysite. this clay mineral is linked to collapsible soil, which moon (2016) has mentioned as one that can yield very suddenly when rapidly loaded. as noted by el jazouli et al. (2020), plasticity is regarded as one of the important parameters in the properties of water retention and corresponding swelling. therefore, larger plasticity correlates to greater volume change that could impact landslide susceptibility. the unified soil classification system (uscs) plasticity chart enabled further classification of the representative soil sample as seen in figure 9. the laboratory-derived atterberg limits (pi=22.37%, and ll=53.46) aided in distinguishing the fines by plotting the values in the plasticity chart. the sample location falls below the “a” line (a line which casagrande emperically plotted in his devised plasticity chart in 1948, separating inorganic clays and silt and organic soils), indicating that the soil sample contains silts and clays with large constituent of „rock flour (finely ground non-clay minerals). the liquidity index (li) or a measure of the consistency of the soil is negative (-0.24), signaling drier nature of the soil than the plastic limit. this is due to the lower moisture content (23.70%), which correlates strongly to the period during which sampling was done (dry season), relative elevation, aspect and fine content (silt). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 75 published by scholink inc. table 1. geotechnical properties of slope soil covering lion mountain landslide location and sample id lion mountain landslide (s9-ft) properties average/mean value physical properties natural moisture content (%) 23.70 specific gravity 2.407 adsorption (%) 16.900 particle size distribution (%) gravel (63mm-2mm) 32.30 sand (2mm-0.063mm) 32.30 fines (silt and clay) <0.063 35.30 consistency limits (%) plastic limit (pl) 31.09 liquid limit (ll) 53.46 plasticity index (pi) 22.37 liquidity index -0.24 figure 9. plasticity chart of the representative soil collected from lion mountain landslide www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 76 published by scholink inc. 5. discussion this study has presented the first detailed assessment of landslide occurrence in an area with little or no anthropogenic activities (e.g., urbanization and deforestation) in the country. on the basis of the analyses above, conclusion could be reached, designating natural conditions as the dominant causative factors for the occurrence of lion mountain landslide. this landslide shows characteristic signatures distinct from the others. this may be linked to the site-specific geo-environmental conditions, particularly the lithological variation and density of tectonic features (fractures, joints and cracks). the rock type is not only susceptible to chemical weathering (the degree of weathering reduces vertically with increasing depth), but shows evidence of discontinuities on the fresh rock and weathered surfaces (upper base and toe of the landslide). this makes the underlying material porous, permeable and direct receipient of the infiltrated rainfall water through percolation in the open joints and porosity. hydrologically, the groundwater level may rise under this condition, which eventually migrates upward to lubricate/wet the overlying soil, thereby reducing its shear strength and increasing landslide susceptibility. at the basal section, there would have been an increment in the joints‟ pore-pressure, which further exacerbated slope instability and subsequent resulted to the failure. geomorphologically, cataclinal slope are susceptible to translational landslides, and slope angle falls within the range of slope angle values that have accounted for many ground failures reported by thomas (1983 &1998). geotechnical investigation revealed the nature, characteristic and type of landslide soil cover. it is a well-graded soil with a percentage of fine fraction greater than gravels (see table 1)-a characteristic contributing to landslide susceptibility. laboratory-derived atterberg limits have shown the soil to be plastic with high expansion potential (ll=53.46). the dcp tested the in-situ soil strength along the soil profile, with the two strength parameters (ultimate bearing capacity and allowable bearing capacity) generally displaying reduction in their values towards the bedrock, indicating weaker layer at the bottom that is prone to to failure. this variation indicates different zones/layers marked by varied modal percentages. the weaker zone indicates greater tendency to slope failure than hard layers. the landslide occurs beyond the depth of plant activities, eliminating any influence of plant root in the event. also, very little or no human intervention exists at bot the slide area and surrounding (e.g., slope profile modification, usually by cutandfill in the area for houses, groundwater modification by a dam, a pipe leak or overflow path modification as in the case of tacugama forest reserve, and bush burning). also, average ubc (1.0744 mpa/1074.4 kn/m 2 ) determined from dcp are within presumed bearng values for the soil (>600 kn/m 2 ). this should be rendering anthropogenic/human factors insignificant in the occurrence of landslide, thereby establishing a close association between geologically unstable ground and landslide events. to adress this, detailed ground investigation (engineering geological mapping) is necessary. this is useful in understanding the relationship between the failed area and their main geological features. also, redshaw et al. (2019), convincingly presented scientific facts linking regent landslide occurrence to deep-seated failures, further implying www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 77 published by scholink inc. evaluation of subsurface conditions. finally, detailed geological studies to understand compositional and tectonic variations in the context of landslide occurrence should be considered to note their unique impacts on landslide characteristics. in addition to this, shear strength property of the soil should be determined, and confirmatory test for the clay type using xrd to further establish the material properties and behaviour. references adegbe, m., agbor, a., onoduku, u. s., asema, a. i., unubi, a. s., & inyang, e. b. (2014). determination of the volume of debris from yingxiu landslides, southwest china: geomorphological and field observation approaches. journal of natural sciences, 2, 95-105. arup, bgs, jba, & integems. (2018). sierra leone multi-city hazard review and risk assessment. in report produced for the world bank global facility for disaster reduction and recovery and the government of sierra leone. the world bank. balzano, b., tarantino, a., & ridley, a. (2019). preliminary analysis on the impacts of the rhizosphere on occurrence of rainfall-induced shallow landslides. landslides, 16, 1885-1901. https://doi.org/10.1007/s10346-019-01197-5 casagrande a classification and identification of soils. (n.d.). transaction, asce, 113, 901-930. chalokwu, c. i. (2001). petrology of the freetown-layered complex, sierra leone: part ii magma evolution and crystallization conditions. journal of africa earth sciences, 32, 519-540. https://doi.org/10.1016/s0899-5362(01)90112-5 chalokwu, c. i., armitage, a. e., & seney, p. j. (2010). petrology of the freetown layered complex, sierra leone: part i. stratigraphy and mineral-chemical evidence for multiple magma injection. international geology review, 1995(3), 230-253. https://doi.org/10.1080/00206819509465402 cruden, d., & varnes, d. j. (1996). landslide types and process. in a. k. turner, & r. l. schuster (eds.), landslides investigation and mitigation. special report 247. transportation research board (pp. 36-75). national academy of sciences, washington dc. cui, y., cheng, d., choi, c. e., jin, w., lei, y., & kargel, j. s. (2019). the cost of rapid and haphazard urbanization: lessons learned from the freetown landslide disaster. recent landslide. https://doi.org/10.1007/s10346-019-01167-x economist intelligence unit. (2002). country profile: guinea, sierra leone, liberia, economist intelligence unit. london. el jazouli, a., barakat, a., & khellouk, r. (2020). geotechnical studies for landslides susceptibility in the high basin of the oumerrbia river (morocco). geology, ecology and landslides. https://doi.org/10.1080/24749508.2020.1743527 garwood, n. c., janos, d., & brokaw, n. (1979). earhquake-caused landslides: a major disturbance to tropical forests. science, 205, 997-999. https://doi.org/10.1126/science.205.4410.997 https://doi.org/10.1007/s10346-019-01197-5 https://doi.org/10.1016/s0899-5362(01)90112-5 https://doi.org/10.1080/00206819509465402 https://doi.org/10.1007/s10346-019-01167-x https://doi.org/10.1080/24749508.2020.1743527 https://doi.org/10.1126/science.205.4410.997 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 78 published by scholink inc. gbanie, s. p., thornton, a., & griffin, a. l. (2015). the diamond of western area is land: narratives of landuse and land cover change in post-confloct sierra leone. australian review of african studies. gogra, a. b., yao, j., tamba, v., kabba, s., sandy, e. h., zaray, g., gbanie, s. p., & bandagba, t. s. (2010). a situational analysis of waste management in freetown, sierra leone. journal of american science, 6(5). kaldor, m., & vincent j. (2006). evaluation of undp assistance to conflict-affected countries: human security: case study sierra leone. united nations development programme evaluation officer, new york. retrieved from https://web.undp.org/evaluation/documents/thematic/conflict/sierra leone.pdf lahai, y. a. (2020). investigating landslide causative factors and modeling using gis and remote sensing techniques (dissertation (mphil) in progress). lahai, y. a., & lahai jr., p. s. (2019). geological context and statistical assessment of the impacts of sugarloaf twin disasters, in western sierra leone. journal of geoscience and environment protection, 7, 226-247. https://doi.org/10.4236/gep.2019.76017 lahai, y. a., anderson, k. f. e., yaguba, j., rogers, i., & kamara, m. (2020). a comparative geological, tectonic and geomorphological assessment of the charlotte, regent and madina landslides, western area, sierra leone. https://doi.org/10.21203/rs.3.rs-16192/v1 martinez, j., avil, g., aguedelo, a., schuster, r. l., casadevall, t. j., & scott, k. m. (1995). landslide and debris flows trigger of the 6 june 1994 paez earthquake, southwestern colombia: landslide news. japan landslide society, 9, 13-15. moon, v. (2016). halloysite behaving badly: geomechanics and slope behavior of halloysite rich soils. clay minerals, 51(3), 417-528. https://doi.org/10.1180/claymin.2016.051.3.09 munro, p. g. (2009). deforestation: constructing problems and solutions on sierra leone‟s freetown peninsula. j polit ecol, 16(1), 104-122. https://doi.org/10.2458/v16i1.21694 redshaw, p., boon, d., campbell, g., willis, m., mattai, j., free, m., … thomas, m. (2019). the 2017 regent landslide, freetown peninsula, sierr leone. quarterly journal of engineering geology and hydrogeology. https://doi.org/10.1144/qjegh2018-187 schuster, r. l., & highland, l. m. (2007). overview of the effects of mass wasting on the natural environment. geological society of america, environmental & engineering geoscience, 8, 25-44. https://doi.org/10.2113/gseegeosci.13.1.25 sesay, i. m., kamara, a., & ngobeh, j. j. (2006). republic of sierra leone: 2004 population and housing census report: analytical report on population distribution, migration and urbanization in sierra leone, statistics sierra leone, freetown, sierra leone. sillah, s. k., turay, e. s., kargbo, y. j., minah, a. a., bangura, a., bao, k., … conteh, r. m. (2019). geological assessment of landslide site at madina hill locality, mortomeh, regent. https://doi.org/10.4236/gep.2019.76017 https://doi.org/10.21203/rs.3.rs-16192/v1 https://doi.org/10.1180/claymin.2016.051.3.09 https://doi.org/10.2458/v16i1.21694 https://doi.org/10.1144/qjegh2018-187 https://doi.org/10.2113/gseegeosci.13.1.25 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 79 published by scholink inc. skrypczak, i., kokozka, w., & jamusz, k. (2017). the impacts of landslides on local infrastructure and the enenvironment. “environmental engineering” 10 th international conference vilnius gediminas technical university lithinia. https://doi.org/10.3846/enviro.2017.049 thomas, m. f. (1983). contemporary denudation systems and the effects of climatic change in the humid tropics—some problems from sierra leone. in d. j. briggs, & r. s. waters (eds.), studies in quaternary geomorphology (pp. 195-214). geo books, norwich. thomas, m. f. (1998). landscape sensitivity in the humid tropics: a geomorphological appraisal. in b. k. maloney (ed.), human activities and the tropical. https://doi.org/10.1007/978-94-017-1800-4_2 undp & epa. (2017). technical publication: analysis of the causal and trigger factors of the august 2017 landslide risk management in freetown, sierra leone. freetown: united nations development programme and environmental protection agency. varnes, d. j. (1978). slope movement types and processes. in r. l. shuster, & r. j. krizek (eds.), special report 176: landslide: analysis and control. transportation research board, national academy of sciences, washington dc. weekes, s. b., & bah, s. (2017). sierra leone 2015 population and housing census. in thematic report on population structure and population distribution. yalcin, a. (2011). a geotechnical study on the landslides in the trabzon province, ne, turkey. applied clay science, 52(1-2), 11-19. https://doi.org/10.1016/j.clay.2011.01.015 https://doi.org/10.3846/enviro.2017.049 https://doi.org/10.1007/978-94-017-1800-4_2 https://doi.org/10.1016/j.clay.2011.01.015 energy and earth science vol. 7, no. 1, 2024 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 original paper a cheap new geological dating method developed from ancient shells study chen guiqing 1 & chen junhao 1 1 guangzhou jinan university 510630, guangzhou, china received: november 25, 2023 accepted: december 7, 2023 online published: march 25, 2024 doi:10.22158/ees.v7n1p1 url: http://dx.doi.org/10.22158/ees.v7n1p1 abstract the vast majority of researchers on ancient shells are biologists, who are not familiar with x-ray diffractometers, etc. we are physical chemists who use x-ray diffraction to observe the changes in the crystal structure of ancient shells? then use wdx electron probe to observe the changes in the microstructure of ancient shells. after discovering shells for a long time, calcite turned into aragonite, overturning the conclusion recorded in geological crystallographic books that aragonite’s structure and physical properties were unstable and would eventually transform into calcite. unexpectedly discovered that the “shuang chen weathering cave cc” of ancient shells has changed over time, it can be used as a new method for geological dating. the use of carbon 14 (c14) isotope geological dating method is quite expensive and lacks accuracy, causing many jokes. the “shuang chen weathering cave cc” of ancient shells may be used as a new geological dating method, and it is quite cheap! keywords marine biology, aragonite structure, calcite structure, d/max-1-a type x-ray diffractometer, wdx electron probe, ccdouble chen weathering cave www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 2 published by scholink inc. introduction authoritative textbooks in china: zhang xi and qi zhongyan’s “outline of shellfish studies” believe that the structure of shells can generally be divided into three layers, with the outermost layer called the stratum corneum, which is only composed of shell elements. the middle layer is a prism layer, which occupies the majority of the shell and is composed of angular columnar calcite (ca1cite). the inner layer is usually composed of leaf shaped aragonite, known as the pearl layer, which is glossy, and pearls are formed from the nacreous layer. this theory has been widely cited and has been read by almost all biology students in china. in the 1980s, we used x-ray diffraction to prove that the conclusion that the shell prism layer is a calcite structure was completely incorrect, which may have been copied from the japanese. however, shellfish expert master hu observed under a microscope and believed that it was still a calcite structure. oh my goodness! in the 1920s, shellfish scientists still don’t know that crystal structure can only be determined by x-ray diffraction. the german physicist roentgen discovered x-rays on november 8, 1895! in the 1980s, huang baoyu, a researcher at the nanjing institute of paleontology, provided ancient shells: schistodesmus sp., schistodesmus lampreyanus (baird & adams), unio douglasiae griffith et pidgeon, and lamprotula hazinic (heude). we use the electron microprobe from the south china sea institute of oceanography, chinese academy of sciences! recently, the corbicula maxima prime shell was borrowed from tan yehui, a researcher at the chinese academy of sciences guangzhou south china sea institute of oceanography, and dr. chen zhiyun, and excavated from the longyan village water conservancy project in shunde, guangdong. collectors: zhao huanting et al. collection time: february 1961. era: 500 to 1000 years ago. measurement date/time: 2015-11-27 9:48:41. using the empyrean x-ray diffractometer from sun yat sen university. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 3 published by scholink inc. the first part comparison of x-ray diffraction lines between modern and ancient shells grind each layer of the shell into powder using an agate mortar and pass it through a 360 mesh sieve. using d/max-1-a x-ray diffractometer and cu target kαx-ray diffraction, under 40kv, 50ma conditions, within 30 minutes from 2θ range 20 0 -80 0 , instrument uses a plot plotter and automatically prints 2θ, absolute strength i and corresponding crystal plane group spacing d. refer the above results to the international universal phase analysis (jcpds) card to determine the crystal structure of the sample. d=0.3399nm, and the horizontal bars at the bottom of the spectral lines are all aragonite structured spectral lines. 1. x-ray diffraction results table 1. x-ray diffraction data of modern and ancient shells modern cristaria plicata(leach) shell powder corbicula maxima pearl layer corbicula maxima prismatic layer corbicula maxima periostracum layer d( nm) i/i0 % d (nm) i/i0 % d(nm) i/i0 % d( nm) i/i0 % 0.3399 99.99 0.2875 100.00 0.3407 5.31 0.3399 90.81 0.3276 51.05 0.2706 58.06 0.3287 2.61 0.3279 54.75 0.2875 11.22 0.1862 1.48 0.2879 10.97 0.2703 54.46 0.2705 79.03 0.1744 2.09 0.2709 100.00 0.2484 46.31 0.2487 41.80 0.1438 5.77 0.2492 16.96 0.2413 20.54 0.2412 16.49 0.1415 32.81 0.2378 27.43 0.2377 56.42 0.2376 53.68 0.1361 3.21 0.2334 13.13 0.2345 36.76 0.2342 37.09 0.1979 1.33 0.2193 16.07 0.2333 33.62 0.1881 1.45 0.2110 28.15 0.2192 14.26 0.1817 2.48 0.1980 100.00 0.2108 31.65 0.1747 42.95 0.1883 50.92 0.1980 100.00 0.1729 21.7 0.1819 41.6 0.1883 47.76 0.1746 46.3 0.1817 37.27 0.1761 5.95 0.1745 50.73 0.1728 30.45 www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 4 published by scholink inc. position [°2theta] (copper (cu)) 10 20 30 40 50 60 70 counts 0 1000 2000 3000 4000 scsmbc007426 nc position [°2theta] (copper (cu)) 10 20 30 40 50 60 70 counts 0 1000 2000 3000 scsmbc007426 zc position [°2theta] (copper (cu)) 10 20 30 40 50 60 70 counts 0 200 400 600 800 scsmbc007426 wc x-ray diffraction pattern: figure 1 modern cristaria plicata (leach) shell powder. figure 2 corbicula maxima pearl layer. figure 3 corbicula maxima prismatic layer. figure 4 corbicula maxima periostracum layer. 2. discussion of results 2.1 the crystal structure of ancient shells is the same as that of modern shells. the prismatic layer is all aragonite structure, which overturns the conclusion of “shellfish outline”. 2.2 the x-ray diffraction pattern of the pearl layer in the corbicula maxim shell appears very special, with the absolute intensity of the strongest spectral line d=0.2875nm reaching i=4290.7 (the maximum intensity of the spectral line in a typical shell is about 700). the spectral lines are very strong, narrow, and few, all of which are thick aragonite grains with obvious “monocrystallization” and no impurity spectral lines. unlike geological crystallography think, where the structure of aragonite is unstable, it will eventually become calcite. but rather development towards a higher degree of single crystal indicates that the structure of aragonite is stable. according to the scherrer formula of x-ray diffraction theory of crystals, the strengthening, narrowing, and decreasing of spectral lines are caused by the growth and thickening of grains in this diffraction direction (preferential orientation growth), which we refer to as the “single crystal tendency”. the growth process of seashells is the growth process of aragonite crystals, constantly in an unbalanced state. due to vacancies or impurities filling the lattice, the lattice distortion changes the spacing between crystal planes and broadens the spectral lines, resulting in new internal stresses. after the death of shellfish, crystal growth stops and no new internal stress is generated. the stress inside the shell gradually releases, vacancies are gradually filled or impurities are gradually eliminated to the www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 5 published by scholink inc. grain boundary to eliminate internal stress. at this time, internal stress is also concentrated at the grain boundary, so this area is prone to weathering. the grains of aragonite continue to grow, therefore; make the spectral lines stronger, narrower, and fewer! due to the corbicula maxima shell, it is less affected by the surrounding soil, which better reflects this process. 2.3 the x-ray diffraction pattern of the prismatic layer of the corbicula maxim shell is similar to that of the pearl layer, with strong, narrow, and few spectral lines. all spectral lines are thick aragonite grains with a “single crystal tendency”, and there are no impurity spectral lines. the absolute intensity of the strongest spectral line d=0.2709nm reaches i=3406.33, which is very strong, narrow, and has very few spectral lines! but because the prism layer is located in the middle of the shell, between the nacre layer and the stratum corneum, the internal stress release is slower, so the spectral lines are slightly more than the nacre layer. it is exactly the same as the pearl layer. from its x-ray diffraction pattern, it appears that many weak spectral lines have become almost flattened and are developing towards a “monocrystalline trend”, similar to the pearl layer above, without impurity spectral lines. 2.4 x-ray diffraction pattern of periostracum layer of the corbicula maxim shell. due to the influence of the epidermis, the spectral lines become more numerous and wider. but all spectral lines are of aragonite structure and have no impurity spectral lines. 2.5 it can be seen from the table that there are more spectral lines in the shell of modern pleated clamshell than that of ancient clam shell. especially from the spectrum diagram is clear at a glance. the aragonite structure of the ancient shell continues to grow, with obvious “monocrystalline”, excluding impurities. modern shells contain some calcite, but ancient shells contain almost no calcite. it shows that after a long age of shells, calcite becomes aragonite! www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 6 published by scholink inc. the second part electron microprobe experiment of four kinds of ancient shells 1. materials and methods in the 1980s, researcher huang baoyu from the nanjing institute of paleontology provided us with four types of ancient shells and explored them using the electron microprobe from the south china sea institute of oceanography, chinese academy of sciences! 2. experimental results 2.1 schistodesmus sp.shell. 102 points, ding village, xiangfen, shanxi, with field number ady201 1983/9/9. era: hundreds to thousands of years. elements with atomic numbers below 11 (na) cannot be measured, therefore; caco3 can only be calculated from the cao molecular formula. the results are shown in table 1. cao+co2--→caco3 mcaco3=(100.089÷56.0794)×mcao=1.784777×m cao. 56.0794 100.0892 inner layer mcaco3=1.78478×48.165=85.964; surface mcaco3=1.78478×45.125=80.538. the same applies below. total in the table ʃ the sum of calcium carbonate and other oxides. sum of electron probe measurements of modern shells ʃ. they are all around 100%, which is caused by errors caused by certain factors and can be normalized to 100%. however, the results of ancient shells are at a certain distance from 100%. this is the result of ancient shells weathering for thousands of years, and we define it as the “shuang chen weathering cave”: cc=100-ʃ. the various parts of ancient shells are different, and the average value cc ------ is taken to represent them. according to the dozens of modern shells we tested, the general result is 98.5<ʃ. therefore, it is assumed that cc values below 2 can be ignored and considered as 0, indicating that there is no “shuang chen weathering cave”. because the range of electron probe testing is very small, important data needs to be measured at several points to obtain the average value, the same below. 2.2 schistodesmus lampreyanus (baird & adams) shell 102 points, ding village, xiangfen, shanxi, 1986/12/16. era: hundreds to thousands of years. the results are shown in table 2. 2.3 unio douglasiae griffith et pidgeon shell. no.102, dingcun, xiangfen, shanxi, with field number ady201 1986/12/16. era: hundreds to thousands of years. the results are shown in table 3. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 7 published by scholink inc. 2.4 lamprotula hazinic (heude) shell. 102 points in ding village, xiangfen, shanxi, with field number ady193 1986/12/16. era: hundreds to thousands of years. the results are shown in table 4. 2.5 modern pinctada martensi (dunker) pearl shell. the results are shown in table 5. 2.6 modern lamprotula mansuyi (dautzenberg et fischer) shell. the results are shown in table 6. 2.7 modern mactra antiquata spengler shell. the results are shown in table 7. 2.8 modern arca (anadara) granosa linnaeus shell. the results are shown in table 8. table 1-8. oxide of shell oxide na2o k2o fe2o3 mno sio2 mgo tio2 al2o3 cao caco 3 ʃ cc cc ------ table 1 ancient schistodesmus sp. inner layer 0.254 0.000 0.000 0.028 0.058 0.040 0.045 0.066 48.165 85.964 86.455 13.54 15.9 table 2 ancient schistodesmus lampreyanus inner layer 0.151 0.005 0.000 0.000 0.044 0.034 0.000 0.040 43.156 77.024 77.298 22.70 19.9 surface layer 0.168 0.008 0.046 0.028 0.103 1.227 0.000 0.046 45.512 81.229 82.855 17.14 surface layer 0.188 0.024 0.092 0.000 0.571 0.146 0.022 0.142 45.125 80.538 81.723 18.28 table 3 ancient unio douglasiae inner layer 0.113 0.026 0.031 0.042 0.029 0.046 0.000 0.061 45.758 81.668 82.016 17.98 19.3 surface layer 0.104 0.000 0.015 0.028 0.073 0.012 0.000 0.030 44.361 79.175 79.437 20.56 table 4 ancient lamprotula sp. inner layer 0.254 0.000 0.092 0.042 0.029 0.000 0.046 46.730 83.403 83.901 83.901 16.10 12.8 surface layer 0.217 0.005 0.230 0.000 0.059 0.000 0.086 50.298 89.771 90.415 90.415 9.58 table 5 modern pinctada fucata martensi pearl layer 0.516 0.007 0.020 0.018 0.038 0.058 0 0.030 55.644 99.313 100.00 0 0 0 prismatic layer 0.429 0.023 0.039 0.000 0.000 0.085 0 0.065 55.670 99.360 100.00 0 0 periostracum 0.282 0.039 0.000 0.000 0.019 1.205 0 0.048 55.137 98.409 100.00 0 0 table 6 modern lamprotula mansuyi pearl layer 0.38 0.03 0.08 0.07 0.37 0.06 0 0.11 55.65 99.323 100.42 3 0 0 prismatic layer 0.59 0.09 0.06 0.11 0.43 0.05 0 0.12 55.67 99.359 100.80 9 0 periostracum 0.25 0.00 0.00 0.04 0.42 0.03 0 0.08 55.38 98.841 99.661 0 table 7 modern coelomactra antiquate a region 0.62 0.02 0.03 0.00 0.02 0.04 0 0.05 55.59 99.216 99.996 0 0 b region 0.60 0.03 0.00 0.02 0.03 0.00 0 0.00 55.65 99.323 100.00 3 0 table 8 modern tegillarca granosa a region 0.56 0.01 0.00 0.04 0.03 0.07 0 0.03 55.61 99.252 99.992 0 0 b region 0.53 0.01 0.00 0.00 0.00 0.07 0 0.03 55.67 99.360 100.00 0 0 www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 8 published by scholink inc. table 9. comparison of the “double chen weathered hole cc” result between ancient and modern shells ancient shell species oxide summation ʃ — double chen weathered hole cc ------ moder shell species oxide summation ʃ — double chen weathered hole cc ------ schistodesmus sp. 84.09 15.9 pinctada martensi shell 100.00 0 schistodesmus lampreyanus 80.08 19.9 lamprotula mansuy shell 100.30 0 unio douglasiae 80.73 19.3 mactra antiquate shell 100.00 0 lamprotula sp. 87.16 12.8 arca (anadara) granosa shell 100.00 0 3. result discussion 3.1 we studied the electron probe electron microprobe detection of 8 samples from 4 ancient and 4 modern shells. as a result, many voids were found in the ancient shell-“shuang chen weathering cave cc” as shown in table 9! we hope it can become a cheap method for dating ancient artifacts! 3.2 in order to achieve the purpose of this article, we sincerely hope that relevant researchers can conduct further research! funding 90 year old commemorative works iv fund project “artificial growth of aragonite crystals and artificial development of pearls” chen guiqing, chen junhao 1985 (approval no. 85084). fund project “research on the structure and imaging mechanism of artificial pearl cores and artistic pearl images” chen guiqing, chen junhao. 1989 (approval number 38870643). references cao, b. x. (2014). ams carbon c14 dating method and analysis. baidu wenku-education-higher education-science. chen, g. q., & chen, j. h. (1988). a study on the crystal structure types of seashells. chinese marine medicine, 1988(1-2), 21-29. https://doi.org/10.2753/ced1061-1932210129 chen, g. q., & chen, j. h. (2017). new conclusion on the crystal structure of pearls and shells. journal of applied oceanography, 36(4). chen, g. q., chen, j. h., & chen, p. (1987). a study on the natural pearls and shells of pinctada martensii. marine medicine, 1986(3), 4-7. https://doi.org/10.2753/ced1061-1932210129 www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 1, 2024 9 published by scholink inc. chen, g. q., chen, j. h., & chen, s. y. (1996). study on the structural components and heating treatment of calcium carbonate medicinal materials (volume 1, volume 2, p. 1670). science and technology literature press. chen, j. h., & chen, g. q. (2018). exploration of crystal structure and application of pearls and shellfish. jinan university press. chen, j. h., & chen, g. q. (2019). the ancient shells are deduced by x-ray diffraction and electron probes. journal of water resources and ocean science, 8(6), 86. https://doi.org/10.11648/j.wros.20190806.11 editorial group of “manual of mineral x-ray powder identification”. (1978). guiyang institute of geochemistry, chinese academy of sciences. kaiichi, m. (1965). zhenzhu chronicle, beilongguan. kobayashi, s., & watanabe, t. (1961). research on pearls 169-176. technical hall. method for determining geological age. (n.d.). 360 library. rock and mineral research office, department of geology, nanjing university. (1978). crystallography and mineralogy. beijing: geological publishing house. ruo, s. (edited and proofread). (n.d.). carbon c14 dating and chinese prehistoric archaeology. zhang, x., & qi, z. y. (1961). outline of shellfish science. science press. zhao, s. r. (ed.). crystallography and mineralogy (p. 412). geological publishing house. curriculum textbooks for higher education in the 21st century. https://doi.org/10.11648/j.wros.20190806.11 energy and earth science vol. 4, no. 2, 2021 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 original paper evaluation of the influence of in situ stress on the stability of mine pit walls: a case study of songwe mine dyson moses 1* , hideki shimada 1 , takashi sasaoka 1 , akihiro hamanaka 1 , tumelo k. m dintwe 1 , joan a. onyango 1 & cho thae oo 1 1 rock engineering and mining machinery laboratory, department of earth resources engineering, kyushu university, fukuoka, japan * dyson moses, rock engineering and mining machinery laboratory, department of earth resources engineering, kyushu university, fukuoka 819-0395, japan received: april 15, 2021 accepted: april 22, 2021 online published: may 25, 2021 doi:10.22158/ees.v4n2p1 url: http://dx.doi.org/10.22158/ees.v4n2p1 abstract the investigation of the influence of in situ stress in open pit mine (opm) projects has not been accorded a deserved attention despite being a fundamental concern in the design of underground excavations. hence, its long-term potential adverse impacts on pit slope performance are overly undermined. nevertheless, in mines located in tectonically active settings with a potential high horizontal stress regime like the songwe mine, the impact could be considerable. thus, using flac3d 5.0 software, based on finite difference method (fdm) code, we assessed the role of stress regimes as a potential triggering factor for slope instability in songwe mine. the results of the evaluated shearing contours and quantified strain rate and displacement values reveal that high horizontal stress can reduce the stability performance of the pit-wall in spite of the minimal change in factor of safety (fos). since mining projects have a long life span, it would be recommendable to consider “in situ stress-stability analyses” for opm operations that would be planned to extend to greater depths and those located in tectonically active regions. keywords in situ stress, dilation angle, finite difference method, flow rule www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 2, 2021 2 published by scholink inc. 1. introduction for decades, the investigation of the influence of in situ stress has been conventionally limited to underground mining studies. in underground mining the analyses focus on failures such as squeezing, spalling and rock bursting which could impact mine safety and production. despite being a fundamental concern in the design of underground excavations, in situ stresses for open pit projects are still not regarded as influential. however, stacey (2007) highlighted the significance of investigating the role of in situ stress in opm on slope instability since excavation creates stress imbalance. as the demand for mineral resources increases to cater for the world booming population, surface mining operations are advancing to greater depths. open pit mining operations are generally cost-effective allowing a high grade of mechanisation and large production volumes and where feasible extract mineral deposits of a very low grade which could not be mined economically using underground methods (sjoberg, 1996). however, slope instability is a major challenge to opm operations. llano-serna, et al. (2016) quantify that roughly, two open pit failures occur worldwide annually. the instability of the slopes documented by far is governed by the slope geometry, rock mass strength, geological structures, shock loading, and hydraulic conditions. stress regimes are hardly factored in among potential triggering factors for mine pit-wall instability. a study by sjoberg (1996) on the bingham canyon mine, currently at 850m depth, concluded that the large scale failures involving up to 2 metric tonnes of material were due to a combined effect of pre-existing discontinuities and excessive water pressure leading to plane shear failure and rotational shear failure respectively. however, though not considered among the factors (sjoberg, 1996) reported that the stress state in the mine was characterised by horizontal stresses being higher than the vertical stress with a k-ratio of greater than 1.1. in south africa, the sandsloot open pit mine is a typical example of an active tectonic environment that encountered instability. the tectonism is characterised by three major joint sets, which relate to the emplacement of the potgietersrus limb. the mine in the area experienced slope failure that prompted a comprehensive study to establish the triggers. without any reference to in situ stress among controlling factors, bye and bell (2001) attributed the principal cause of the slope instability at the mine to the steep dipping and persistent joints. at buzhaoba mine in china, the failure that occurred was loosely attributed to tectonic stress as a dominating factor (chen et al., 2019). according to the analysis, the principal stress direction that was theorised and simulated at 123º showed that as the excavation progressed to a deeper horizon, the cumulative effects of stress were exhibited through rock mass deformation and instability along the direction of the principal stress. in the case of songwe mine, it is sited within the active tectonic setting of the malawi rift system (mrs) that is part of the main east african rift system (ears). therefore, this work builds on the hypothesis that high in situ stresses, especially in tectonically active environments, could have a critical influence in opms. accordingly, this contribution is aimed at evaluating the accruing influence of in situ stress and its role as a potential triggering factor for slope instability. www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 2, 2021 3 published by scholink inc. 1.1 location and geology of the study area songwe mine is expected to perch at songwe hill situated in phalombe district southern malawi (figure 1a) .the hill has a north-south diameter of 800m and measures 450m east to west. in terms of regional geology, the area is underlain by crystalline rocks of precambrian to lower palaeozoic age referred to as the malawi basement complex which are intruded into by alkaline intrusive bodies (garson & smith, 1965; british geological survey, 2009). the emplacement of these alkaline intrusions occurred during the late jurassic—early cretaceous period which affected an area approximately 300-400 km in diameter in the south of malawi and in mozambique (figure 1a). the local geology of the study area is principally composed of; carbonatite and fenite surrounded by a massive intrusion of syenite (figure 1b). carbonatite, which is the ore hosting rock, occurs in three categories namely: coarse-grained calcite carbonatite (sovite); fine-grained carbonatite (alvikite); and fe-rich ferroan calcite carbonatite (broom-fendley et al., 2017; broom-fendley et al., 2017b; simandl & paradis, 2018). fenites form an aureole around the carbonatite intrusion. large blocks of encapsulating fenite show evidence of being in situ, hence the carbonatite intrusion never reached the surface beyond roofing fenite (broom-fendley et al., 2017). structurally, the site is within the active tectonic environment of the malawi rift system (mrs) that is part of the main east african rift system (ears). therefore, faulting and the development of joints may not be an uncommon phenomenon. however, the structural disruption at the carbonatite complex is not vividly reflected on a large scale except for a major fault on the eastern side of the hill that runs nw to se. the subtle evidence of structural deformation is revealed in sharp lithological breaks across the hill. figure 1. location and geology of study area (modified after broom-fendley et al., 2017) www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 2, 2021 4 published by scholink inc. 2. method 2.1 numerical methods numerical methods are capable of simulating natural failure process and representing deformation and displacement of the failing rock mass (diederichs et al., 2007; matsui & san, 1992; hammah et al., 2004; dawson et al., 1999). analysis based on a numerical approach involves dividing the rock mass into elements assigned with the idealised stress-strain relation and properties that describe how the material behaves. the most commonly applied numerical methods in slope stability analysis are divided into three categories: (i) continuum methods, (ii) discrete methods, and (iii) hybrid continuum/discrete methods. in this study, a continuum code based on the finite difference method (fdm) using flac 3d 5.0 software (itasca, 2012) was applied in simulating the potential slope instability. the fdm approach was preferred because the constitutive models are treated with no modification to the solution algorithm as such the modeling is justifiably more accurate for plastic collapse loads and plastic flow (itasca, 2012). the analysis was performed in elasto-plastic state in finding the solution with the mohr-coulomb constitutive model and failure criterion. the shear strength reduction (ssr) technique embedded in the fdm code achieved the determination of slope performance. the ssr involves a methodical iterative search of the factor of safety (fos) value that stretches the slope to the limits of failure. the roller boundary conditions were assigned in the xand y-direction thereby fixing the boundary planes in the xand y-direction respectively, pinned boundary condition (i.e., constrained in the x-, yand z-directions) was applied at the bottom of the model and the top of the model was left unconstrained. 2.2 model construction the hill dimensions guided the numerical model of the pit. the opm at the site is anticipated to cover almost the whole stretch of the hill. the overall dimensions of the final pit are expected to be approximately 650 m north to south and 400 m east to west. regarding pit height, it is planned that the deepest level will be 300 m when measured from the highest reduced level (rl) of the pit on the southern side of the pit (figure 2). accordingly, the simulation model stretches 1000 m in length, 400 m in height, and the width measures 400 m. the 100 m addition in length on both ends was to make sure that the boundary conditions do not influence the solution when stepping. monitoring points were added at the mid-section of the pit to observe displacements and induced stresses on the pit walls. the excavation of the stack benches (dimension 15 m height and 7.5 m width) was done in three sequential stages. three conceptual cases were generated with respect to pit height. in the first scenario, shear strain behaviour on the pit-slope was investigated at the current planned depth of 250 m. the planned depth is within the bounds of proven ore reserve hence the geological confidence is high. the second scenario is for 280 m depth and the third case is based on the ultimate depth of 300 m. at this depth, the geological confidence is relatively low since less than 10% of the drilled holes reached 300 m. the www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 2, 2021 5 published by scholink inc. analysis was performed at the trial steep overall angle of 45º (moses et al., 2020) in the non-associated flow rule (ψ=0°) and associated flow rule (ψ≠0°). the two flow rules are conducted to comprehend both the worst-case and idealistic scenario of rock mass deformation. the material properties used in this study are presented in table 1. rock density , uniaxial compressive strength (ucs), young’s modulus (e), tensile stress , friction angle , cohesion (c), poisson ratio (v) and dilation angle (ψ) were obtained from laboratory rock strength tests conducted except for syenite lithological unit, which were sourced from literature. table 1. mechanical properties of the rock units rock type ucs (mpa) (g/m 3 ) e (gpa) (mpa) (deg) c (mpa) ψ (deg) v carbonatite 83.2 2.78 45.30 8.6 35 0.32 2.3 0.28 fenite 118.6 2.70 44.40 10.4 36 0.30 3.5 0.29 phonolite 150.4 2.88 64.30 11.5 37 0.45 3.5 0.29 syenite* 70.0 2.55 53.40 3.37 30 0.28 0.25 note. *based on empirical values (katz et al., 2000; croll et al., 2014). www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 2, 2021 6 published by scholink inc. (a) cross section of songwe open pit mine (b) model extents figure 2. cross section of the mine and numerical model 3. result and discussion in evaluating the stability of excavation, the factor of safety (fos) is utilised as an index to determine the performance of the excavated sections. in this study, the evaluation of the safety of the pit slope is based on the mohr-coulomb failure criterion as presented in the equation in figure 3, which is a classic approach in geotechnical studies (labuz & zang, 2012). the application of the criterion in fdm utilises the shear strength reduction (ssr) technique that entails a systematic iterative search for a value that stretches the slope to the limits of failure. when fos, derived as a ratio between supply (shear strength) and demand (shear stress), is ≥ 1 the excavated face is described as stable and if < 1 it is unstable. 400 m 1000 m 400 m www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 2, 2021 7 published by scholink inc. figure 3. mohr coulomb failure criterion relation note. where: is the shear strength; c is cohesion; is internal friction angle; is normal stress. 3.1 pit wall stability in most mining engineering projects, analyses are performed without incorporating dilation angle as a parameter since the interest is in the worst-case scenario. however, we considered both the non-associative flow rule (ψ=0°) and the associative flow rule (ψ≠0°) because dilatancy is one of the crucial phenomena of geo-materials during shear distortion of elements in a material. the results of the analysis are shown in figure 4. the simulation outcome indicates that the pit walls are satisfactorily stable at 250 m pit height. the values of fos are well above the threshold of 1.2 as recommended by (adams, 2015; read & stacey, 2010; sullivan, 2013) for opm. however, the performance of the pit walls falls under the threshold implying unreliable stability as the excavation extends to a deeper horizon. the comparative analysis of the non-associated flow rule (ψ=0°) and associated flow rule (ψ≠0°) illustrates that taking into account ψ improves the stability performance of the pit wall slopes. the dilation angle of the rock mass appears to increase the shear strength of the rock mass under shearing conditions. this increase in strength can be ascribed to the rearrangement of the constituent mineral grains in the rock mass as shearing occurs. in an intact rock state, the mineral grains are interlocked and as such, they do not have the freedom to move. when stressed, the contiguous mineral grains gravitate towards each other, which ultimately produces a bulk expansion of the material due to occlusion. the findings concur with the pioneering empirical formulas by bolton and reynolds on the effect of dilation angle (logani, 1973). we can observe that the consideration of ψ is vital to yield accurate and realistic slope stability besides the fact that engineering considers the worst-case scenario. www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 2, 2021 8 published by scholink inc. 250m 280m 300m 1.10 1.15 1.20 1.25 1.30 f ac to r o f s af et y ( f o s ) pit height (m) non-associative flow rule (ψ=0°) associative flow rule (ψ≠0°) figure 4. pit stability condition at different excavation depth to appreciate the influence of dilation angle on slope performance in details, we undertook a parametric analysis by varying the values of dilation angle. the averaged dilation angle was changed within the range of 0°-20°. the findings of the parametric analysis are given in figure 5. the results affirm that the dilation angle enhances the stability of the excavated faces. higher values of dilation angle yielded relatively larger stability values when compared to the conventional non-associative flow rule. this phenomenon underscores the positive correlation of the associated flow rule of ψ in increasing the shear strength of the rock mass on excavated slopes under shearing conditions. having appreciated the stability conditions under a unit stress condition (k=1), the study explores further for varied stress conditions, and the results of the analysis are based on the non-associated flow rule (ψ=0°). 0° 3° 6.5° 10° 13.5° 17° 1.10 1.15 1.20 1.25 1.30 1.35 f ac to r o f s af et y ( f o s ) averaged dilation angle (deg) 250m pit height 280m pit height 300m pit height figure 5. parametric analysis of the influence of dilation angle on the stability of pit walls www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 2, 2021 9 published by scholink inc. 3.2 influence of in-situ stress in open pit mine the pre-mining initial stress state is an important aspect in numerical modeling for equilibrium stepping and determination of mining induced stress. to understand the influence of the in-situ stress state during rock excavation, the virgin stresses were analysed. in this research project, due to unavailability of site-specific data, which is technically complex and expensive to collect, the pre-mining stresses were approximated from mean south african regional stress compilation in opms; impala, parabola, and rustenburg mines grouped as a, b, and c respectively, carolusberg and klerksdorp mine which portray identical directional pattern to malawi (figure 6). thus, different stress ratios ( ) were considered to appreciate the influence they could have on the stability of the pit walls. based on the regional data, it can be observed that the mean ratio between vertical stress and major horizontal stress can be tested up to k=2.5 in open-pit mines. the initial run of the simulation was based on the in situ stress ratio of k=1 and then varied at 0.5 intervals. the results of the analysis are displayed in figure 7. the outcome shows that the stability of the pit, as adjudged quantitatively from fos, could negligibly be affected even under high-stress conditions. as observed from figure 7, the factor of safety remains the same under different stress regimes except when the pit start to extend to deeper levels at 280 m and 300 m pit height which recorded a marginal decrease from 1.16 to 1.15 and 1.12 to 1.11 at k=1 with the increase in stress ratio respectively. since the determination of stability is quantitative, this phenomenon explains why in situ stress is conventionally considered in underground mines. however, a qualitative evaluation of the stability state through shearing contour analysis reveals that the pit wall stability conditions would be different under high-stress regimes that could potentially influence the long-term performance of the slope. although the factor of safety experiences minimal reduction, it is evident that the pit wall shearing becomes intense and the straining of the walls becomes effusive under high-stress ratio conditions. in this situation, it should be appreciated that with the passage of time, the pit walls could potentially fatigue under high in situ stress. in addition, if the depth extend further, the minimal accrual could translate into a significant value of fos. thus, as a “first check” in the evaluation of the stability of a pit slope, we apply the strain-based approach to failure prediction and determine if further attention regarding monitoring could be necessary to incorporate the trigger action response plan (tarp) for instability in different stress regimes. www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 2, 2021 10 published by scholink inc. kmean vs depth 0 500 1000 1500 2000 2500 3000 3500 0 1 2 3 4 5 6 kmean d e p th (m ) all a,b and c data impala plats. rustenburg plats. carletonville klerksdorp n.c.gay 1975 (a) mean stress ratios for representative opm (b) location of data representative mines figure 6. the averaged ratio of vertical stress and maximum horizontal stress 3.3 the strain criteria approach to failure prediction the essence of pit wall stability analysis is to evade or inhibit failures by adopting an optimal mine design. therefore, the strain-based approach, as applied in this study, could provide guidance regarding strain thresholds for pit wall performance in diverse stress conditions. strain is the ability of a stressed material, in the presence of a stress field, to deform. generally, rock mass succumbs to the application of stress which is due to the rearrangement of the natural in situ stress field when the slope is excavated. the extent of straining is consequent to the slope geometry and slope construction and in situ stress conditions. the strain-based approach to assessing pit slope stability utilises the fundamental principles of the strain formula after brix & newcomer (2003) given as. where: =the maximum deformation of the pit wall, h=the total height of the wall and ε=the strain in percentage. based on over 12 case studies, brox & newcomen (2003), newcomen & dick (2016) and zavodni in hastrulid (2001) developed the strain percentage criteria for the principal failure modes in various rock mass classes. the threshold strain levels for rock mass were established to have a lower bound strain at collapse of 0.1% and upper bound strain to collapse of 3% (newcomen & dick, 2016; coetsee et al., 2020). the results of the stability performance of pit wall, based on strain approach, against failure under different stress regimes are given in figure 8. it can be observed that the peak strain rate increases with stress regimes. that is, as the k-ratio increases, the straining correspondingly increases. www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 2, 2021 11 published by scholink inc. shear contours shear contours k-ratio = 1 k-ratio = 1.5 shear contours shear contours k-ratio = 2 k-ratio = 2.5 (a) shearing pattern of pit walls at 250 m pit height shear contours shear contours k-ratio = 1 k-ratio = 1.5 shear contours shear contours k-ratio = 2 k-ratio = 2.5 (b) shearing pattern of pit walls at 280 m pit height shear contours shear contours k-ratio=1 k-ratio=1.5 fos=1.23 fos=1.23 fos=1.23 fos=1.23 fos=1.15 fos=1.15 fos=1.16 fos=1.15 fos=1.12 fos=1.11 www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 2, 2021 12 published by scholink inc. shear contours shear contours k-ratio=2 k-ratio=2.5 (c) shearing pattern of pit walls at 300 m pit height figure 7. shearing pattern under different stress conditions this trend is in tandem with the qualitative shearing conditions of the pit wall previously presented in figure 7. however, the percentage of strain in this study demonstrates that the pit walls would be almost 60% below the lower bound strain to collapse in all the simulated cases. the highest strain rate of almost 0.04% is recorded at 300 m height with the highest possible in situ stress condition of k=2.5. thus, at this rate of straining the pit walls stability performance would still be guaranteed though relatively high. the pit height is also an important determinant of straining on pit slopes. the outcome shows that as the pit extends to a deeper horizon, the strain rate congruently increases. at the ultimate pit limit (upl) of 300 m, the strain values are comparatively high against 280 m and 250 m pit heights. for example, at the stress condition of k=2.5, the strain values are 0.029% at 250 m, 0.032% at 280 m and 0.036% at 300 m pit height. k=1 k=1.5 k=2 k=2.5 0.00 0.01 0.02 0.03 0.04 s tr ai n ( % ) stress ratio (σ_h⁄σ_v) 300m pit height 250m pit height 280m pit height figure 8. peak strain of pit walls against potential failure under different stress regimes fos=1.11 fos=1.11 www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 2, 2021 13 published by scholink inc. 3.4 displacement pattern to check the criticality of the stability state, in connection to the strain analysis, the extent of displacement was evaluated under different stress conditions. the results of total displacement with respect to k-ratio are depicted in figure 9. it can be observed that the pattern of displacement is in harmony with the strain state such that an increase in stress ratio led to increase in the extent of total displacement. at 250 m pit height, the peak displacement values are 19 mm, 57 mm, 74 mm, and 107 mm at k=1, k=1.5, k=2 and, k=2.5 respectively. contours contours k-ratio = 1 k-ratio = 1.5 contours contours k-ratio = 2 k-ratio = 2.5 (a) pit wall displacements at 250 m pit height contours contours k-ratio = 1 k-ratio = 1.5 contours contours k-ratio = 2 k-ratio = 2.5 (b) pit wall displacements at 280 m pit height www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 2, 2021 14 published by scholink inc. contours contours k-ratio=1 k-ratio=1.5 contours contours k-ratio=2 k-ratio=2.5 (c) pit wall displacements at 300 m pit height figure 9. pit wall displacement under different stress conditions as excavation progressed, the extent of displacement gradually increased. that is, at 280 m pit height, the displacement values recorded are 19 mm, 58 mm, 83 mm and 109 mm in the order of increasing stress ratio. and at the currently planned upl the displacements are 21 mm, 59 mm, 83 mm, and 149 mm at k=1, k=1.5, k=2, and k=2.5 respectively. the deformations around the pit are generally induced by relaxation on the excavated pit sections. corollary, increase in maximum initial horizontal stress appear to counter the gravity loading effect, hence lateral material movement becomes more dormant to vertical movements. from the displacement trends, we can observe that in situ stress condition is indispensable for consideration in opm as they could have a long-run compounding effect on pit wall performance. 4. conclusion the significance of investigating the role of in situ stress in opm cannot be over-emphasised as surface mining operations are advancing to greater depths with the safety of mines being among paramount concerns. in this contribution, the influence of in situ stress and its role as a potential triggering factor of slope instability was assessed. the evaluation of the shearing contours and quantified strain rate and displacement values demonstrate that high horizontal stress regimes can reduce the stability performance of the pit-wall. even though the quantitative outcome based on fos gives a guised impression of no significant impact as values of stability remain almost constant, this scenario could have adverse impacts on the long-term stability performance of the pit slope since mining projects extend for years. this calls for a perspective transformation of the conventional approach of confining in situ stress impact in solely underground excavations. therefore, this work suggests that “in situ stress-stability analysis” is a worth consideration for opm operations that would be planned to extend www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 2, 2021 15 published by scholink inc. to greater depths, and those located in tectonically active settings. acknowledgement the authors express their sincere gratitude to mkango resources company for providing the required geotechnical data for the study to be conducted. references adams, b. m. (2015). slope stability acceptance criteria for opencast mine design. new zealand: golder associates (nz) limited. british geological survey. (2009). malawi potential of malawi. zomba: malawi government. broom-fendley, s., brady, a. e., horstwood, m. s., woolley, a. r., mtegha, j., wall, f., & gunn, g. (2017). geology, geochemistry and geochronology of the songwe hill carbonatite, malawi. journal of african earth sciences, 134, 10-23. https://doi.org/10.1016/j.jafrearsci.2017.05.020 broom-fendley, s., brady, a. e., wall, f., gunn, g., & dawes, w. (2017). ree minerals at the songwe hill carbonatite, malawi: hree-enrichment in late-stage apatite. ore geology reviews, 81, 23-41. https://doi.org/10.1016/j.oregeorev.2016.10.019 chen, s., lai, g. t., han, l., & tovele, g. s. (2019). effects of tectonic stresses and structural planes on slope deformation and stability at the buzhaoba open pit mine, china. sains malaysiana, 48(2), 317-324. https://doi.org/10.17576/jsm-2019-4802-07 coetsee, s., armstrong, r., & terbrugge, p. (2020). the use of strain threshold in slope stability trigger action response plans. australian centre for geomechanics, 339-352. https://doi.org/10.36487/acg_repo/2025_18 croll, r., swinden, s., hall, m., brown , c., beer, g., scheerpers, j., & trusler, g. e. (2014). ni 43-101 pre-feasibility report. johannesburg, south africa: msa group (pty) ltd. dawson, m. e., roth, w. h., & drescher, a. (1999). slope stability analysis by strength reduction. geâotechnique, 49(6), 835-840. https://doi.org/10.1680/geot.1999.49.6.835 diederichs, m. s., lato, m., hammah, r., & quinn, p. (2007). shear strength reduction (ssr) approach for slope stability analyses (pp. 319-327). london: taylor and francis group. https://doi.org/10.1201/noe0415444019-c39 garson, m. s., & smith, c. w. (1965). carbonatite and agglomeratic vents in the western shire valley. zomba: geological survey department. hammah, r. e., curran, j. h., yacoub, t., & corkum, b. (2004). stability analysis of rock slopes using the finite element method. canada: eurock & 53rd geomechanics colloquium. schubert. itasca. (2012). fast lagrangian analysis of continua in 3dimensions user’s guide (5th ed.). minneapolis, minnesota: itasca consulting group inc. https://doi.org/10.1016/j.jafrearsci.2017.05.020 https://doi.org/10.1016/j.oregeorev.2016.10.019 https://doi.org/10.17576/jsm-2019-4802-07 https://doi.org/10.36487/acg_repo/2025_18 https://doi.org/10.1680/geot.1999.49.6.835 https://doi.org/10.1201/noe0415444019-c39 www.scholink.org/ojs/index.php/ees energy and earth science vol. 4, no. 2, 2021 16 published by scholink inc. katz, o., reches, z., & roegiers, j. c. (2000). evaluation of mechanical rock properties using a schmidt hammer. international journal of rock mechanics and mining sciences, 37(4), 723-728. https://doi.org/10.1016/s1365-1609(00)00004-6 labuz, j. f., & zang, a. (2012). mohr-coulomb failure criterion. rock mech rock eng, 45, 975-979. https://doi.org/10.1007/s00603-012-0281-7 logani, l. k. (1973). dilatancy model for the failure of rocks. michigan: lowa state university. matsui, t., & san, k.-c. (1992). finite element slope atability analysis by shear strength reduction technique. japanese society of soil mechanics and foundation engineering, 32(1), 59-70. https://doi.org/10.3208/sandf1972.32.59 moses, d., shimada, h., sasaoka, t., hamanaka, a., dintwe, t. k., & wahyudi, s. (2020). rock slope stability analysis by using integrated approach. world journal of engineering and technology, 8, 405-428. https://doi.org/10.4236/wjet.2020.83031 newcomen, w., & dick, g. (2016). an update to the strain-based approach to pit wall failure prediction. the southern african institute of mining and metallurgy, 116, 379-385. https://doi.org/10.17159/2411-9717/2016/v116n5a3 read, j., & stacey, p. (2010). guidelines for open pit slope design. australia: sciro publishing. https://doi.org/10.1071/9780643101104 simandl, g. j., & paradis, s. (2018). carbonatites: related ore deposits, resources, footprint, and exploration methods. applied earth science, 127(4), 123-152. https://doi.org/10.1080/25726838.2018.1516935 sjoberg, j. (1996). large scale slope stability in open pit mining. sweden: division of rock mechanics; lulea university of technology. sullivan, t. d. (2013). pit slope design and risk—a view of the current state of the art. the south african institute of mining and metallurgy, 51-80. https://doi.org/10.1016/s1365-1609(00)00004-6 https://doi.org/10.1007/s00603-012-0281-7 https://doi.org/10.3208/sandf1972.32.59 https://doi.org/10.4236/wjet.2020.83031 https://doi.org/10.17159/2411-9717/2016/v116n5a3 https://doi.org/10.1071/9780643101104 https://doi.org/10.1080/25726838.2018.1516935 energy and earth science vol. 3, no. 2, 2020 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 36 original paper air quality management for electroplating industry for mumbai metropolitan region, maharashtra yogesh gore 1,2 & awkash kumar 3* 1 north maharashtra university, jalgaon, maharashtra, india 2 maharashtra pollution control board, mumbai, maharashtra, india 3 sustainable approach for green environment, powai, mumbai, maharashtra, india * awkash kumar, sustainable approach for green environment, powai, mumbai, maharashtra, india received: june 4, 2020 accepted: june 16, 2020 online published: august 23, 2020 doi:10.22158/ees.v3n2p36 url: http://dx.doi.org/10.22158/ees.v3n2p36 abstract electroplating is considered to be a major polluting industry because it discharges toxic materials and heavy metals through effluent like wastewater, air emissions and solid wastes. there are many registered electroplating units in mumbai metropolitan region (mmr). the quantities of gaseous wastes generated from these industries were estimated and the existing control and treatment techniques for these gaseous wastes were evaluated. further, air quality modeling (aqm) study was also carried out to predict the concentration of acid mist with the help of emission, characteristics of stack and meteorology. a gaussian plume model based screen view software was used to predict concentrations for two industries which showed that the acid mist emissions from stack were under the consented limits. further, health impact survey was performed at 1km radius of the industry to study the effects of air pollution on human health. it showed that 47%, 40% and 57% workers near the electroplating industries are suffering from chest pain, eye irritation and breathlessness respectively. clustering of electroplating industries in the mmr will improve the waste management in the region. installation of efficient air pollution control equipment like wet scrubbers can eliminate the hazards caused due to acid mist emissions from electroplating industries. keywords electroplating, acid mist, health impact monitoring, fugitive emissions www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 37 published by scholink inc. 1. introduction air pollution has become a popular issue in the terms of social aspects (muthukaruppan et al., 2010). plantation is carried out to mitigate the air pollution issue in the region (bora & joshi, 2014; thakar & mishra, 2010). electroplating is the process of deposition of a fine layer of one metal on another through electrolytic process to impart various properties and attributes, such as abrasion & wear resistance, corrosion protection, enhanced surface hardness, lustre, colour, aesthetics and value addition (akolkar, suresh, varalaxmi, & kumari, 2015). electroplating uses electric current and electrochemical reaction for making metal coatings (selhi & nikhil, 2014). it is considered to be a major polluting industry because it discharges toxic materials and heavy metals through wastewater (effluent), solid wastes and air emissions into the environment. the effluent from electroplating industries have high concentration of heavy metals like iron, chromium, copper and nickel (singh, 2014). there are many registered electroplating units, located in mumbai metropolitan region (mmr). these plants are divided into region i, ii, iii, iv. many of these industries are operated at a small scale and hence environmental compliance and waste management is not given due importance. due to the high treatment costs, the wastewater, solid waste and gaseous emissions from these industries are released without any prior treatment leading to deterioration of nearby land, air and water. small scale entrepreneurs owning these electroplating industries and the employees there are either ignorant of health impacts or environmental effects of effluent discharge or are worried that it would be a financial burden to them (singh, 2014). electroplating industry has been generating a huge amount of waste in the forms of wastewater, spent solvent, spent process solutions and sludge (freeman, 1988). solid waste includes residues such as cleaning powder, buffing compounds generated during the pre-treatment process and spent anodes during the plating process. liquid wastes includes spent chemicals and solutions such as acids, alkali, cleaning agents, bath chemicals comprising plating chemicals as well as additives such as brighteners, levellers etc. and rinse waters. gaseous wastes include solvents and vapours from hot pre-treatment and process baths. acid alkali mist and volatile organic compounds (vocs) are the gaseous wastes from electroplating industries. in some cases, mists and vocs may contain metals in addition to process chemicals. mist is produced when gases generated at the electrodes during the process rise to the surface as bubbles, then burst, and spray fine particles of the plating solution into the atmosphere above the surface (mason, lorimer, saleem, & paniwnyk, 2001). air emissions from electroplating industries may contain toxic organic materials such as trichloroethylene and trichloroethane (singh, ram, & kumar, 2016). around 30% of the used solvent and degreasing chemicals release voc (cushine, 1985) (united states environment protection agency, 1980). the minimization of the air emissions to be adopted is related to the optimum bath temperature control and the preventive maintenance of the suction and filtration unit or scrubber (ramesh babu, udaya bhanu, & seeni meera, 2009). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 38 published by scholink inc. the disposal of untreated effluent from electroplating industries into the environment can cause toxicity to aquatic flora and fauna, sewage toxicity, ground and surface water pollution and it can also cause problems in biological treatment process employed for treatment of sewage (nair, chandrakar, & nandkumar, 2016). in this study, electroplating industries of mmr region were assessed for various gaseous pollutants with the help of stack monitoring. the health of people residing in 1km radius from the electroplating industry was monitored to check for the health hazards caused due to improper waste management. 2. study area the study focuses on the electroplating industries confined in mumbai metropolitan region (mmr). the study area shown in figure 1 highlights the mmr, maharashtra. the mmr spreads over 4,355 sq. km. consists of 8 municipal corporations along with more than 1,000 villages in thane and raigad districts. mumbai metropolitan region development authority (mmrda) is responsible for the development of the mmr. due to rapid urbanization, the region was illegally developed in a haphazard manner. it has many registered electroplating units. these units are divided in region i, ii, iii, iv. project synopsis focuses on the industries located in region ii of mmr. two electroplating industries from region ii of mmr were visited and the general information about these industries is given in table 1. the main source of wastes from electroplating units are identified as drag out losses, concentrated liquid wastes, spent acid bath, spent alkali baths, spent passivation dip and rinse water. the effluents from electroplating industries have high concentration of heavy metals like iron, chromium, copper and nickel. as example, in india, river quality yamuna river quality has deteriorated due to discharge of untreated or inadequately treated industrial effluents from nearby electroplating industries into the river (singh, 2014). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 39 published by scholink inc. figure 1. mumbai metropolitan region table 1. general information of the industries visited s.no. name of the industry water consumption (lpd) waste water generation (lpd) solid and hazardous waste generation (kg/m) existing pollution control methods 1 industry a 2000 400-500 10 hood system for pickling unit 2 industry b 3000 2000 30 hood system and wet scrubber note. industry names have been hidden for confidentiality. n www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 40 published by scholink inc. 3. methodology the data for the study was collected in two stages, i.e., air quality study and its health impact. the focus of the study was to check for the air pollution levels due to acid mist. two industries were selected to carry out air pollution studies based on emissions and meteorology. ground level concentrations were predicted. air quality study was conducted to obtain the existing acid fume concentration in the work place. it also gives an idea about dispersion of pollutant from stack within a certain range. a gaussian plume based modeling software screen view was used to find out the dispersion of emission from stack which aided in prediction of concentration of pollutants around stack. screen view software also gives an idea about the modifications required in the technology to reduce the emission concentration from stack. this software was used with the help of general meteorological condition for finding ground level concentration of effluent from a stack at a particular hour. a questionnaire was prepared to establish a relation between the waste management of electroplating industries and its impact on the health and well-being of the workers. the suitability of the work place for the workers was checked, along with the health complications the workers have due to the acid mist. survey was done around the region of industry a electroplaters and industry b, located at jogeshwari and goregaon respectively. health monitoring study was done on 47 people around the periphery of 500 m of the industries. survey was conducted on people of 15-60 years of age residing in the vicinity of the industry. maximum people surveyed were of the age 26-35 years which is the working population of the region. workers who are routinely exposed to the emissions are susceptible to adverse health impact (singh, 2014). heavy metal exposure has been known to cause developmental retardation, different types of cancers, kidney damage, and even death in some instances of exposure to very high concentrations (glover-kerkvliet, 1995). a bio-monitoring study, conducted to assess the exposure in the electroplating industry showed that exposure to chromium and nickel compounds in the electroplating industry occurs via combination of inhalation, dermal and ingestion routes (beattie et al., 2017). 4. results and discussion the results obtained from the air pollution modelling study and human health impact assessment are discussed in section 4.1 and 4.2, respectively. 4.1 results of air pollution study the occupational safety and health administration (osha) is responsible for administering and enforcing the federal osh act of 1970. these regulations set out uniform national standards for workplace safety and health practices throughout the country. according to osha, the maximum allowed concentration of acid mist is 7 mg/m 3 . acid mist is a mist containing a high concentration of acid or particles of any toxic chemical. the input data consisted of emission rates, stack height, stack diameter, exit velocity and temperature of gases, ambient air temperature and wind speed. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 41 published by scholink inc. 4.1.1 industry a electroplaters industry a electroplaters had filter bags installed to control the air pollution caused due to fugitive emissions. this industry has a hood system connected to the pickling unit to control source emission/fugitive emission but the hood system was not provided at electrochemical bath. air quality studies were conducted to analyse the emissions from the stack of industry a electroplaters. the input data is given in table 2. table 2. input data source type point emission rate (g/s) 0.049 stack height (m) 3.04 stack inside diameter (m) 1.0 stack exit velocity (m/s) 1.4 stack gas exit temp (k) 310 ambient air temp (k) 293 wind speed (m/s) 1 the modelled results, as shown in table 3, and the graph, as shown in figure 2, gave details of the automated distances and concentrations at 100 m intervals from the stack. as the stack was short and large, it was found that ground level concentrations at 1m distance from the stack were the highest. the concentrations were found to be inversely proportional to the distances. table 3. modelled results distance (m) concentration (µg/m3) 1 71.57 100 57.7 200 25.2 300 17.21 400 11.90 500 8.69 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 42 published by scholink inc. as given in table 3, the maximum concentration of acid mist at ground level was 71.57 µg/m 3 which is less than the prescribed limits. hence, it can be concluded that the bag filters installed by industry a electroplaters for controlling fugitive emissions were working efficiently. and the hood provided for controlling acid mist emissions was beneficial. to decrease the emissions further, the stack height needs to be increased and the stack diameter should be decreased. figure 2. automated distances vs. concentration 4.1.2 industry b industry b is located in goregaon east and specializes in jewelry coating. the pollution control unit here had hood systems connected to wet scrubber to control source emission/fugitive emission. the input data for industry b is given in table 4. the emission rates for industry a and industry b were found to be almost the same. however, the emission levels at the ground level differed for the two industries due to the difference in the stack heights. table 4. input data source type point emission rate (g/s) 0.0427 stack height (m) 6.1 stack inside diameter (m) 0.80 stack exit velocity (m/s) 2.98 stack gas exit temp (k) 310.00 ambient air temp (k) 293.00 wind speed (m/s) 1 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 43 published by scholink inc. the diameter of the stack in industry b. was smaller and hence there was proper dispersion of the emissions and the concentration at the ground level near the stack was significantly lower compared to industry a electroplaters. the modeled results for industry b are given in table 5. table 5. modeled results from table 5 and figure 3, it can be concluded that the higher stack height and smaller diamater leads to better dispersion of gaseous pollutants and the pollutant concentration found at the ground level near the stack is almost negligible. highest concentration was observed at a distance of 100m from the stack and was found to be 37.63 µg/m 3 which is significantly lower than the standards prescribed by osha. this implies that the industry is taking sufficient air pollution control measures for treating the acid mist that is generated during the electroplating process. figure 3. automated distances vs. concentration distance (m) concentration (µg/m 3 ) 1 0.00 100 37.63 200 14.30 300 11.97 400 8.98 500 6.84 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 44 published by scholink inc. 4.2 results from questionnaire for health impact studies the results obtained from the questionnaire survey for the health impact study has been summarized in this section. figure 4. percentage responses of people on various health impacts figure 4 gives the results of the survey and it can be seen that the chest problem (47%) is the most predominant health issue faced by the people living in the vicinity of the industry, followed by eye irritation at 40% and skin problems at 26%. figure 5. percentage representation of response of people who said yes www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 45 published by scholink inc. as seen from figure 5, among all the people who reported of having any health issue, the maximum number of people (37%) have chest related problems while the minimum number of people (10%) have mucous membrane irritation problem. around 32 % of the people claimed of experiencing eye irritation. this can be due to the fumes that are generated in the electroplating operations like pickling, degreasing and electrochemical bath. it was observed that the people above 35 years of age were more susceptible to health problems than the younger people. response for chest related problems the most common health problems in electroplating industry are related to chest. this could be due to the constant exposure to toxic chemicals and fumes which were emitted into the atmosphere without any prior treatment. figure 6 shows results from the survey which was specifically focused on chest related problems like breathlessness, chest tightening, watering eyes and blocked/runny nose. during this survey, it was observed that many of the people were claiming to have these problems. figure 6. percentage responses for chest health issues www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 46 published by scholink inc. figure 7. percentage representations of people who said yes and had chest issues it can be observed from figure 7 that more than half of the people approached claimed to have some form of chest problems like bouts of coughing and breathlessness. among the people with chest problems, 9% people reported chest tightness, 23% reported bouts of coughing, 9% of them have running/ blocking nose, 16% were suffering from watering eyes, 18% were having the problem of wheezing. the maximum number of people (25%) claimed to have breathlessness while watering eyes and bouts of coughing can also be seen as major problems. these health issues could be due to the long term exposure to acid mist which is present in high concentration in the ambient air in the region. people living near the industries which do not use scrubbers and fume hoods are at a great risk of heavy exposure to these acid fumes. it was also observed in the survey that the people were mostly suffering from chest problems and respiratory disorders as these fumes were affecting their lungs. 5. conclusions and recommendations electroplating industry generates gaseous emissions, wastewater and solid waste. acid mist is predominant in the air emissions because of extensive use of highly concentrated acid. very few industries have proper control technology for treating liquid effluent and gaseous emissions. since most of these industries are operated at small scale, they cannot afford to have proper control and treatment equipment. installing such treatment equipment will increase the cost of their products compared to the rest of the market. screen view modeling software was conducted to find the acid mist dispersion concentration from the stack. it was observed that emissions from industries undertaken for study were below the consented limit of acid mist from stack given by maharashtra pollution control board (mpcb). the modeling study showed that the concentrations of acid mist at ground level were 71.57 µg/m 3 and 37.63 µg/m 3 for industry a electroplaters and industry b, respectively. it can be concluded from the study that in order to have lower acid mist concentrations at ground level, higher stack height and smaller stack diameter should be provided. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 47 published by scholink inc. from the results of the health monitoring survey, it can be concluded that majority of the people who are staying around the electroplating industries are suffering from chest problems, eye irritation and ulcers. immediate steps need to be taken in order to protect the health of the people living in nearby areas. installation of scrubbers will control acid mist emissions. also, minimizing the use of raw material, reducing the drag out losses, modification of rinsing technique, and replacement of hexavalent chrome by trivalent chrome can further reduce the negative impacts in the environment caused due to electroplating industries. installation of air pollution control equipment like electrostatic precipitator, fabric filters, cyclone separators and settling chambers should be done for removal of particulate matter. acid fumes hood should be used for coverage of fugitive emissions through ventilation process. however, coverage of fugitive emissions should be done by providing hood to collect acid fumes through ventilation process. clustering is recommended for the electroplating industries in the mmr region. shifting all the electroplating industries to a common place will directly affect the growth and development of the industry. it will also help in stabilizing the electroplating market. references akolkar, a. b., suresh, s., varalaxmi, h. d., & kumari, a. (2015). report on assessment of environmental compliance in electroplating units at bengaluru. bengaluru: central pollution control board, south zonal office. beattie, h., keen, c., coldwell, m., tan, e., morton, j., mcalinden, j., et al. (2017). the use of bio-monitoring to assess exposure in the elctroplating industry. journal of exposure science and environmental engineering, 27, 47-55. https://doi.org/10.1038/jes.2015.67 bora, m., & joshi, n. (2014). a study on variation in biochemical aspects of different tree species with tolerance and performance index. the bioscan, 9, 59-63. cushine, g. (1985). electroplating wastewater pollution control technology. park ridge, n. j. noyes data corporation. freeman, h. (1988). waste minimization audit report: case studies of minimization of cyanide waste from electroplating operations. epa. glover-kerkvliet, j. (1995). environmental assault on immunity. environmental health perspectives, 103(3), 236-237. https://doi.org/10.1289/ehp.95103236 mason, t. j., lorimer, j., saleem, s., & paniwnyk, l. (2001). controlling emissions from electroplating by the application of ultrasound. environ. sci. technol., 35, 3375-3377. https://doi.org/10.1021/es001944r muthukaruppan, k., sowmya, m., prasad, m. v. r., & satpathy. (2010). ambient air quality at igcar campus, kalpakkam. the bioscan, 2, 383-390. https://doi.org/10.1038/jes.2015.67 https://doi.org/10.1289/ehp.95103236 https://doi.org/10.1021/es001944r www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 48 published by scholink inc. nair, s., chandrakar, m., & nandkumar, p. (2016). a review on methods available for removal of cadmium: with special reference to electroplating industrial waste water. international research journal of environment sciences, 5(10), 61-66. ramesh, b. b., udaya, b. s., & seeni, m. k. (2009). waste minimization in electroplating industries: a review. journal of environmental science and health, part c: environmental carcinogenesis and ecotoxicology reviews, 27(3), 155-177. https://doi.org/10.1080/10590500903124158 selhi, a., & nikhil, s. (2014). a study of electroplating process through experiment and simulation (pp. 439-1-439-5). 5th international and 26th all india manufacturing technology, design and research conference (aimtdr), iit guwahati. singh, r. k. (2014). pollution threat to surface and ground water quality due to electroplating industries. international journal for research in applied science and engineering technology (ijraset), 2(ii), 50-53. singh, v., ram, c., & kumar, a. (2016). physico-chemical characterization of electroplating industrial effluents of chandigrah and haryana region. journal of civil & environmental, 6(4). https://doi.org/10.4172/2165-784x.1000237 thakar, b. k., & mishra, p. c. (2010). dust collection potential and air pollution tolerance index of tree vegetation around vedanta aluminium limited, jharsuguda. the bioscan, 3, 603-612. united states environment protection agency, e. (1980). proposed guidelines for drinking water quality criteria for the protection of aquatic life and its uses. federal register 45. https://doi.org/10.1080/10590500903124158 https://doi.org/10.4172/2165-784x.1000237 energy and earth science vol. 7, no. 2, 2024 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 original paper flare pollution loads and carbon-dioxide effect on rainwater acidity in niger-delta: a review, investigation and model for safe living quarter ugwunna d. amadi 1* & godpower c. enyi 1 1 department of petroleum and gas, university of salford, m4 5wt, united kingdom * ugwunna d. amadi, department of petroleum and gas, university of salford, m4 5wt, united kingdom received: july 7, 2024 accepted: july 18, 2024 online published: august 12, 2024 doi:10.22158/ees.v7n2p1 url: http://dx.doi.org/10.22158/ees.v7n2p1 abstract carbon-dioxide does not only affect climate change, but also contribute tremendously in acidification of rain water. hazard identification and risk assessment are fundamental components of effective risk management, specifically in sensitive areas where adverse effects can have significant consequences. this study provides novel methodology for environmental and safety assessment of flared gases in sensitive areas such as residential homes. distancing sampling technique (dst) was used to investigate the sensitivity of rain water ph at distances away from flare site in order to develop a risk management model for sensitive regions. first, a review on rain water acidity was made around flaring and non-flaring areas in niger-delta states, which revealed moderate-high acidity effect around flaring zones and no effect on non-flaring zone. secondly, flared gas quantification, ph experimental evaluation (pee) and risk assessment matrix (ram) were the three systematic approaches used respectively to quantify, measure and evaluate the effects of co2 and other flare pollutants around the area of study. an average of 809,300,000 mscf of associated petroleum gases were flared around the oil and gas producing areas in delta state, causing a release of around 43x10 6 tons of co2 from 2012-2022. experimental results showed the range of ph from 4.56 ± 0.06 to 5.10 ± 0.06 for the 33 samples of harvested rainwater in kwale community, delta state causing a deviation of 16.38 to 30.05% from standard. the developed and validated model suggests 4.81km radius as the safe distance for human habitation from flare sites. based on these findings, carbon-capture and sequestration projects must be activated in niger-delta to curb the menace. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 2 published by scholink inc. keywords acid rain, distance sampling, standard deviation, risk matrix, co2 sequestration 1. introduction the need to address risk issues in a continuously evolving environment, coupled with improved information and communication technologies has led to the development of several techniques, hazard identification and risk assessment methods (villa & cozzani, 2015). risk analysis by dynamic approach have been an evolving method for identifying, assessing, and quantifying increasing risk in a system with uncertainty, real-time changing environment, and system complexity (bucelli, et al., 2018; villa & cozzani, 2015). a systematic approach for defining safe residential quarters due to pollution by flared gases around flare regions are still lacking. nduka, j. et al. (2008), collected rainwater samples from portharcourt and warri, which are two major oil and gas industrial areas in niger-delta, to determine the water ph, while control samples were collected from awka in anambra state, which was non-oil and gas hub. the samples were collected up to 115m from a reference point in a triangular equilibrium using clean plastic basins. the ph readings are as follows: portharcourt (4.71,4.94,4.93); (5.04,5.73,4.91): warri (4.81,4.70,6.15);(4.79,4.80,4.72): awka (6.04,5.88,5.75); (6.00,5.10,5.96). the ph of rainwater in portharcourt and warri, were highly acidic due to industrial activities (gas flaring) while the ph of awka acting as control is within acceptable range. odjugo, p. & osemwenkhae, e. (2009), determined the effects of gas flaring on crops grown in niger-delta. the results of their work reveals that the flare affects extends beyond 110 meters from the flare location and therefore advised on further studies to validate the claim. atuma, m. i., & ojeh, v. (2013), examined the effect of flared gases on soil and casava productivity from five sites in ebedei, ukwani lga of delta state in niger-delta. the soil samples were harvested at varying depths and distances ranging from 0 20cm and 50m 250m respectively from the bund wall of the flares. critical analysis using multiple regression and paired t-test methods shows wide acidity variation in the results obtained in flaring area to those from the controlled site (non-flaring area). however, the researchers did not attempt to model a safe threshold for human habitation in those areas due to adverse effects of rain acidity. in this research, environmental assessment of risk of co2 and other flare pollutants was investigated by evaluating the ph of rainwater around delta state, a region in niger-delta, which was conducted 2km from flare sites for two consecutive years. the study was aimed at providing simple methodology for safety and environmental assessment of flared gases in sensitive areas at defined distances from flare sites followed by measuring the ph of the water and modelling safe human quarters. ph is an incredible parameter that plays a key role in assessing water quality. in environmental sampling and monitoring, the ph value indicates the pollution index of the water, which has potential adverse effect www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 3 published by scholink inc. on the environment, people and ecosystem. on the light of the above, the present work on impact assessment focuses more on the influence of flared gases on rainwater acidity at specific intervals up to 2km. niger-delta region of nigeria has proven natural gas reserves of 203.16 trillion cubic feet (tcf) and crude oil reserves of 36.89 billion barrels (bb) and between 400 tcf-600 tcf of undiscoverable natural gas reserves. this is estimated to be within 7.7% -15.5% of global quantity of undiscoverable natural gas resources. judging by the trend, some considerable amount of the associated gases when produced would be flared leading to huge economic loss and consistently endangering human health, ecosystem and general environment. acid rain and most environmental pollutant have been widely attributed to impact of gas flaring especially in the niger delta region of nigeria (elijah 2022; ebong, et al., 2022; nwankwo & ogagarue, 2011). gas flaring does not only affect climate change but also pollutes the environment, with utmost effect to inhabitant in close proximity to flare sites. hazard identification, risk assessment and mitigation plan are keys for prevention of chances of diseases, calamities and mishaps in sensitive areas. 2. review of literature rainwater is water fallen as rain that has not collected soluble matter from the soil and is therefore soft. it is also a surface water obtained from rain fall, which is an excellent source of domestic water for rural areas and dispersed population (anyata, 2008; odume, 2022). water is essential for the environment, human health, food security and sustainable development, whose quality is an indispensable requirement for healthy living (schiller, 1982; adeyeye, et al., 2019). it becomes a problem to humanity, ecosystem and the environment when the physical and chemical balances of the water chemistry are altered due to natural or anthropogenic activities. acid rain is a normal rain acidified by certain air pollutants. rain water acidification is a serious environmental problem of trans-boundary nature caused by the oxides of sulfur and nitrogen and worsened by increasing amount of carbon-dioxide in the atmosphere (singh & agrawal, 2007). whereas the normal rain cleanses, supports, enriches life and the environment, acid rain dirties and damages life, ecosystem and the environment (abbasi, et al., 2013). acid rain is considered by many as one of the grave environmental threat of our time caused by air pollution that have led to fish extinction and forest dieback (grennfelt et al., 2020). acidic rain poisons our water bodies and lowers the soil ph. lowered soil ph leaches away nutrients cations and increases the exposure of heavy toxic metals, which reduces soil chemical properties that enhances soil fertility. when the soil chemistry is compromised, it impacts negatively on growth and productivity of plants and forest trees. basically, the degree of acidity of water and soil is measured by ph, which is a shorthand version of potential hydrogen. figure 1 displays the origin of pollutants that www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 4 published by scholink inc. acidifies rain water, cause climate change and other environmental threats. figure 1. cause and effect diagram for environmental pollutants which acidifies rain water 2.1 gas flaring proximity to residential areas in niger-delta, there are widespread perceptions that due to human habitation in close proximity to flare locations, it has adversely affected the region in terms of human health status, environmental degradation, and social-economic issues (nriagu et al., 2016; otache et al., 2021). this is due to daily released amount of the dangerous toxins into the atmosphere, resulting to the pollution of air, water, soil and the ecosystem (oghenejoboh et al., 2007). the impact of gas flaring spreads across extensive radius from the point of generation. in niger-delta at least two million (2,000,000) people lives within four kilometres (4km) (2.5 miles) in flaring locations (noaa virtual night flare, 2018). figure 2. yellow spots showing population of residential homes at less than 2km from flare sites in niger-delta source: global gas flaring tracker report, july, 2020; https://gasflaretracker.ng/ www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 5 published by scholink inc. these emissions have caused series of litigation from the host communities to the oil and gas company, government agencies, resulting to claims and counter claims (nduka et al., 2008). flaring as a major source of greenhouse gases generates noise and heat leading to health issues and environmental degradation (emam, 2015; capp 2012; abiodun, 2014; oseji, 2007; ejiogu et al., 2019). scientific studies have identified over 250 toxins released from flaring. they include carcinogens such as benzopyrene, benzene, carbon-disulphide (cs2), carbonyl-sulphide (cos) and toluene. others are metals such as mercury, arsenic and chromium, sour gas with h2s and so2, nitrogen oxides (nox), carbon-dioxide (co2), methane (ch4) etc which contributes to greenhouse gases (epa 2014; christiansen et al., 2016; mobolaji sunmoni, 2018). 2.2 specific effects of acid rain specifically, acid rain affects human health, damages the soil, plants, trees as wells as buildings and structures (singh & agrawal, 2007; abbasi et al., 2013). acid rain not only damages the chemistry of soil but also changes the quality of soil (fiza fatima et al., 2021). it distorts the enzymes of microbes in the soil, kills them, leaches the soil essential nutrients, decreases soil fertility and causes stunted growth of plants (singh & agrawal, 2007; atuma & ojeh, 2013). acid rain washes heavy metal toxins like magnesium (mn), aluminium (al), lead (pb), iron (fe), mercury (hg) and gets them dissolved in the soil, which permeates down to the ground drinking water and poisons it. while some of these toxins are washed off and flows to the rivers, lakes and streams (nwankwo & ogagarue, 2011; ejiogu et al., 2019; ebong et al., 2022). the accumulated heavy metals in human bodies through ingestion of the poisoned water, causes headache, irritation of throat and nose, coughs etc. excess ingestion of these toxins contributes to kidney and heart issues, lung diseases such as asthma, bronchial problems, etc. direct exposure of human body to acidified liquids affects the immune system, which drastically reduces human antibodies (nagae et al., 2011). the direct droplet of acidic rain water lowers the ph of the water bodies therefore adversely affects the living things in the water. accumulation of heavy metals in the water bodies affects the breaths of fishes leading to premature deaths. the above phenomenon equally affects the food chain at different levels. when humans eat these poisoned fishes, the heavy metals will be deposited into the human body, also when animals or birds eat the dead fishes; they also become a secondary receiver of the poisoned food. 2.3 chemistry of co2 release from combustion process flared gases are composed of various forms of gases (methane, ethane, propane, butane, pentane, hexane, etc.), water vapour, hydrogen sulphide, nitrogen, volatile organic matters, etc. (peterson, 2007; putriastuti, et al., 2021). during gas flaring, the combusted gases generate mainly carbon-dioxide (co2), water vapor and heat (gzar & kseer, 2009). this is evident in equations (2.1-2.5). www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 6 published by scholink inc. the presence of co2 in the atmosphere causes acidity of rain water according to the chemical reactions blow. in equation (2.6), carbon dioxide (co2) reacts with rainwater (h2o) to form carbonic acid. the presence of hydrogen ion molecules “h +” in the water renders it acidic by lowering the ph as shown in equation (2.7). accumulation of h + due to higher concentration of co2 from combustion process further acidifies the rain water. 3. materials and methods in this research, a field work around a flare location in a community in kwale area of delta state was carried out. the sole purpose was to measure the ph of rain water harvested in the format describe in figure 3 and in three stages as described in figures 4, 5 & 6. a measurement tape, machete, labeled white plastic bowls, labeled retrieval bottles, beaker and a digital ph meter were the key apparatus used for the field sampling and experimental evaluation. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 7 published by scholink inc. figure 3. model for rain water sampling points: f=farm area; r=residential area; x1,x2,x3=sampling axis with sampling points. 3.1 research method the sampling stages and experimental scenarios follow the sequence defined in figures 4, 5 & 6 of this report. 3.1.1 stage 1: chart for rain water harvesting and ph experimentation along axis x1 total of thirty three (33) rain water samples were harvest from axis x1, x2, x3 for the three (3) stages of field work as describe below. figure 4 is the first stage done which involves sampling points clearing, positioning of bowl for rainwater collection and ph experimentation. four points cleared in day 1, seven points in day 2 while the bowls were positioned on the eleven cleared points in day 3, followed by ph evaluation in day 4. figure 4. sampling and ph evaluation timeline along x1 axis www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 8 published by scholink inc. stage 2: chart for rain water harvesting and ph experimentation along axis x2 figures 5 & 6 is the second stage of the sampling and experimentation process along axis x2 and x3.the process includes sampling points clearing, bowls positioning and ph evaluation in the laboratory for the harvested water samples. figure 5. sampling and ph evaluation timeline along x2 axis stage 3: chart for rain water harvesting and ph experimentation along axis x3 figures 3 & 4, is the last stage of the sampling and experimentation process along axis x3 done in the third year of this research. the process is in similar fashion with stages x1 and x2. figure 6. sampling and ph evaluation timeline along x2 axis where; x1, x2, x3=axis of measurement p1, p2, p3 … p11=sampling points; b1, b2, b3 … b11=sampling bowls ph.s1, ph.s2, ph.s3…….ph.s11=evaluated ph of each retrieved water samples www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 9 published by scholink inc. 3.1.2 assessment of flared gases and co2 in niger-delta using quantification approach the amount of flared gases and emitted co2 over 11 years (2012-2022) as monitored by nigeria gas flare tracker, an online software was use to quantify the volume of flared gases (mscf) released on daily basis in niger-delta states and its environ. earth observation group (eog) at the colorado school of mines in 2011 developed this satellite software that tracts and records flaring data with locations, temperature, source, sizes and radiant heats from infrared emitters worldwide. in nigeria, this software is monitored via (https://gasflaretracker.ng) and managed by national oil spill detection and response agency (nosdra). table 1 displays volume of flared gas vis-a-vis the amount of co2 respectively emitted in edo, delta, rivers, bayelsa, akwa-ibom, imo and abia state. these are the states that comprise niger-delta. table 1. 11 years profile of emitted carbon-dioxide (x10 3 tonnes) from flared gases (x10 3 mscf) in niger-delta states yr. edo delta rivers bayelsa akwai-ibo m imo abia f.gas x103 e.co2 x103 f.gas x103 e.co2 x103 f.gas x103 e.co2 x103 f.gas x103 e.co2 x103 f.gas x103 e.co2 x103 f.gas x103 e.co2 x103 f.gas x103 e.co2 x103 2012 12200 648.9 49000 2600 55400 2900 30400 1600 3700 197.3 15100 800.1 45.9 2.4 2013 19100 1000 67600 3600 57500 3100 34500 1800 6800 359.9 16400 869.5 1300 71.3 2014 21200 1100 62200 3300 68100 3600 36200 1900 5500 294.1 9400 500 1000 54.1 2015 21600 1100 65900 3500 56800 3000 26500 1400 6100 322.2 7500 397.9 458.8 24.4 2016 9900 527.6 52400 2800 68000 3600 37000 2000 5700 304.8 8400 444.5 132.9 7.1 2017 14100 746.9 69600 3700 70000 3700 36200 1900 6000 316.8 7600 404.9 451 24 2018 24800 1300 113200 6000 65700 3500 45500 2400 5900 312.7 6600 353.8 1200 64.5 2019 24800 1300 105200 5600 68900 3700 47000 2500 4600 246.5 8200 435.2 1100 56.8 2020 17800 947.8 99700 5300 57900 3100 42400 2300 3100 164.8 10300 545 603.1 32 2021 16900 897.8 66300 3500 38600 2100 23500 1200 2500 130.3 6900 366.3 385.5 20.5 2022 12900 684.1 58200 3100 31800 1700 18100 1000 2500 130.9 4600 241.8 0 0 note. where: f.gas=flared gas; e.co2=emitted co2. 3.1.3 experimental procedure thirty three (33) samples were collected at intervals of 200 meters (0.2km) from the bunk wall of a typical flare site to a distance of 2km along axis x1, x2 and x3. the task includes clearing of sampling points, positioning of water collection bowl and laboratory investigation. upon retrieval of the harvested rain water in labeled receptacles, standard quantity of 100ml of the sample was measured and poured into a calibrated beaker, and the digital ph meter was switched on www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 10 published by scholink inc. for 30 minutes to warm up, next was calibration of the unit in a buffer solution. the sample was stirred for 2 minutes, the electrode rinsed, the meter set in ph mode and the electrode inserted into the beaker followed by activating the ph measurement button. a stable ph reading was achieved within 60 seconds. after each reading the electrode was rinsed with distilled water and second and third reading done on same sample for result comparison. by implication, all harvested rain waters were tested thrice for data validation using same procedure. 3.1.4 rain water ph analytical procedure the evaluated ph data was analyzed by risk matrix approach using percentage standard deviation method. risk is a function of probability of occurrence of an undesired event in addition with a measure of its adverse consequence. the procedure involves identification of the hazards, quantification of likelihood and consequence of those hazards on health and environment. standard deviation is a measure of amount of dispersion or variation from the data set. it specifically gives a clue on how far each value lies from the average or mean. a high standard deviation indicates that the values are far from the mean and vise verse. this approach was used in this research to analyze the rain water ph along x1, x2 and x3 axis and compared with the standard mean (ẍ) value of 5.6. the standard percentage deviation (spd) for the harvested rain water ph data was computed in excel spreadsheet using equation (3.1). presented in table 2 and 3 are the flared gas risk assessment matrix and risk factor respectively employed as tools for the risk evaluator based on the magnitude of the flare pollutants effects on the people, community or environment. the risk factor (r.f) is a product of probability of occurrence (likelihood) and severity. mathematically, where; ; www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 11 published by scholink inc. table 2. risk assessment matrix www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 12 published by scholink inc. table 3. risk factor 3.1.5 impact rating and description negligible-low risk zone (nlrz): it is characterized with negligible effects from flaring activities but mitigation measures may be desirable. the flare impact may not result to significant effects on the people, community or environment even if ignored. low-medium risk zone (lmrz): it is characterized with significant impact, requiring mitigation to curb the effects. the flare impacts may results to negative short-to-medium term effects on the people, community or environment. medium-high risk zone (mhrz): it is characterized with serious impact requiring immediate mitigation plan to drastically curb the menace. the flare impacts may result to a medium-to-long term effects on the people, community or environment. high-critical risk zone (hcrz): it is characterized with severe impact on the people, community and the environment if adequate steps are not employed to stem it. the flare impact may have already resulted to a long term adverse effect on the people, community or environment around that zone. critical-intolerable risk zone (cirz): it is characterized with very severe impact on the people, community and environment. these effects are usually immitigable if the practice continues. the only panacea is to stop the practice generating the effects. 3.2 model for determining safe habitation quarter in sensitive areas in order to predict the safe human habitation zone from flare locations, r-squared was used to study the variance of the independent variable (distance) to the dependent variable (ph), using the mean regression equation. r-squared is a coefficient of determination in statistical regression model for evaluating the proportion of variance of the variables (dependent from independent) which defines the goodness of fit from their relationship. based on the generated r-squared value, which is more than 80% for the mean ph as shown in figure (12), a regression model was developed. the regression equation along the path of investigation is defined by: www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 13 published by scholink inc. = = by gaussian elimination method = 3.3 risk evaluation model generic risk model at varied distance, xi 4. results and discussion this research was done by quantifying the amount of released carbon-dioxide vis-à-vis emitted flared gases for 11 years in seven states of niger-delta. this is followed by determination and analyzation of the ph value of 33 samples collected at 200 meters interval and finally evaluating the safe zone for human habitation from flare locations. all data were calculated via excel worksheet, graphical figures developed analyzed using origin 2023(10.0) software. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 14 published by scholink inc. figure 7. emitted flared gas profile for 11 years in niger-delta state 4.1 volume of emitted gases vis-a-vis of co2 released for 10 years in niger-delta states figure 8. area profile of emitted co2 per state in niger-delta the basic function of the satellite flaring data software is to detect the amount of gas flared on daily basis. which includes the amount of carbon-dioxide (co2) emitted from the flared gases, economic value of the flared gases as well as the potential power generation from the flared gases. table 1 shows the amount of co2 respectively emitted in edo, delta, rivers, bayelsa, akwa-ibom, imo and abia state. within these periods under study (2012 2022), niger-delta region has cumulatively flared 2,180,677,000 mscf of natural gas with the release of 115,749,500 tonnes of co2 in the air space within the study period. the trend revealed delta state taking the lead on the amount of emitted co2 from flared gases within the period of 2018 till 2022. this is closely followed by rivers www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 15 published by scholink inc. state and bayelsa state at the second and third place. apparently, (195,300,000 mscf; 10,253,100 tones), (809,300,000 mscf; 43,000,000 tones), (638,700,000 mscf; 34,000,000 tones), (377,300,000 mscf; 20,000,000 tones), (52,400,000 mscf; 2,780,300 tones), (101,000,000 mscf; 5,359,000 tones) and (6,677,200 mscf;357,100 tones) were the flared volume and emitted co2 volume respectively emitted from edo state, delta state, rivers state, bayelsa state, akwa-ibom state, imo state and abia state. the result showed 809,300,000 mscf of natural gas has been flared for the 11 year period with a release of 43,000,000 tonnes of co2 in delta state alone where the investigation was carried out. the study area is a community in kwale area located in delta state where flaring activity is done on daily basis and at different locations, which poses great concerns on human’s lives at close proximity to these flaring sites. 4.2 ph of 33 harvested rain water samples along x1, x2, x3 and mean (ẍ) the lower the ph of a substance the stronger its acidity, and the higher the ph the higher the alkalinity of that substance. in this work, a ph value of 5.6 is the mean used to analyze the measured ph of the 33 water samples harvested at axis x1, x2 and x3 as shown in figure (3). clean rain water has a ph of 5.6 (singh & agrawal, 2007; abbasi, et al., 2013; xuan et al., 2021; al hameli et al., 2022). ph evaluated on the harvested rain water samples ranges between 4.56±0.06 to 5.10±0.06, which are indisputably below clean rain water ph of 5.6 and are all acidic. figures 9, 10, 11 & 12 are four graphical representation of the measured ph along the three axis of evaluation, x1,x2,x3 and the mean ph {ẍ=(x1,x2,x3)/3}. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 16 published by scholink inc. figure 9. ph measurement along x1 axis figure 10. ph measurement along x2 axis figure 11. ph measurement along x3 axis figure 12. mean ph estimate for x1.x2 and x3 axis figures 9, 10, 11 & 12 disclose stronger acidity near the flare location, which eases slowly away from it. this could be attributed to the phenomenon known as dry and wet deposition as well as pollutant plume dispersion. in dry deposition process, the pollutants settles/fall under gravitational influence usually close to the point of origin (source of generation), where it reacts and acidify water body or soil in contact. in wet deposition, the pollutant got scavenged in the cloud, travels by dispersion and falls wet at some distance from the generated location due to the influence of wind. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 17 published by scholink inc. figure 13. overview ph measurement along the three axis 4.3 risk matrix evaluation results the calculated standard deviation of the 33 rain water samples and the risk rating results using the evaluation tools (risk assessment matrix, risk factor) are displayed as shown in table 4. table 4. risk rating and control measure # deviation d:@x1 deviation d:@x2 deviation d:@x3 % mean ď: @x1,x2,x3 severity (s) prob. of impact (pf) risk factor (rf) risk rating rir) remark/panacea 1 29.8496 31.3572 28.9451 30.0506 3 e 3e high stop gas flaring/ capture & sequester co2 2 22.3118 28.9451 23.8194 25.0254 3 d 3d high stop gas flaring/ capture & sequester co2 3 20.5028 22.0103 22.9149 21.8093 3 d 3d high stop gas flaring/ capture & sequester co2 4 23.8194 20.8043 27.4375 24.0204 3 d 3d high stop gas flaring/ capture & sequester co2 5 23.8194 22.3118 20.8043 22.3118 3 d 3d high stop gas flaring/ capture & sequester co2 6 19.2967 20.8043 19.8998 20.0003 3 d 3d high stop gas flaring/ capture & sequester co2 7 25.9299 19.5982 20.5028 22.0103 3 d 3d high stop gas flaring/ capture & sequester co2 www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 18 published by scholink inc. 8 18.6937 21.7088 17.1862 19.1962 5 b 5b medium stop gas flaring/ capture & sequester co2 9 15.3771 20.5028 17.1862 17.6887 4 b 4b medium stop gas flaring/ capture & sequester co2 10 18.9952 17.4877 15.0756 17.1862 4 b 4b medium stop gas flaring/ capture & sequester co2 11 15.3771 17.4877 16.2816 16.3821 3 c 3c medium stop gas flaring/ capture & sequester co2 figure 14. ph standard deviation along the sampling points the main objectives of risk assessment matrix is to identify potential vulnerability to environment and health followed by defining situations management, compare alternatives, provide knowledge on patterns of events and to identify critical parts of the operations. risk assessment matrix evaluated the magnitude of the deviation of the experimental results from instituted standards. it weighs the severity of potential risk against the probability or likelihood the risk might occur. in table 2, a scale of consequences of 0, 1, 2, 3, 4 & 5 were used to designate increasing severity at the vertical axis, and likelihood scale of a,b,c,d & e at the horizontal axis that designated the probability of the adverse effects on the people, environment and ecosystem. the risk matrix evaluator was utilized to generate the risk factor (rf) from the evaluated standard percentage deviation (spd) of the rain water ph along axis x1, x2 and x3 as shown in table 3. this is considered reliable tool for analyzing and standardizing quantitative risk by categorizing all threats to safety, health, and environment based on their deviation from the acceptable limit. the risk factor (rf) www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 19 published by scholink inc. was estimated from equation (3.2) by multiplying the “severity in the vertical column to the likelihood in the horizontal row” and consistently noting the corresponding color codes in the risk matrix evaluator. for example, the ranking codes 2a, 3a and 4a are same as 2xa, 3xa and 4xa respectively. equation (3.1) was used to calculate the standard percentage deviation (spd) with 5.6 as the mean rain water ph. the evaluated spd along x1, x2 and x3 axis ranges from 15.3770% 29.8496%, 17.4877% 31.3572% and 15.0756% -30.0506% respectively. from the results, the calculated mean standard deviation ranges from 16.39% 30.05%, which falls within the blue and yellow color coded zones. the deviation at the blue zone is designated (10.01-20%), which covers 2c, 2d, 2e, 3b, 3c, 4b and 5b color coded background as shown in table 2. for analytical purpose, the deviation is distributed amongst the rf which is seven in number within the blue zone. this is done by first calculating the deviation difference and dividing it by the total number of rf in that zone, followed by apportioning the common factor to each of the risk factors, i.e.,{(20-10.01)/7=1.43%}. the value “1.43” is added successively to each of the rf’s. the range of application of 2c, in the blue code zone is: 2c=(10.01%-11.44%) which means 2c lies within 10.01% to 11.44%. others 2d, 2e, 3b, 3c, 4b and 5b are designated 2d=(11.45%-12.87%), 2e=(12.88%-14.3%), 3b=(14.44%-15.87%), 3c=(15.88%-17.31%), 4b=(17.32%-18.75) and 5b=(18.76%-20%)}. in the same vein, at the yellow coded zone, the deviation ranges from (20.1-50%), with the risk factors (3d, 3e, 4c, 4d & 5c) and having {(50-20.01)/5=5.98%} as the common factor. the range of application of 3d, 3e, 4c, 4d, & 5c in the yellow coded zone are {3d=(20.1%-26.08%), 3e=(26.09%-32.07%), 4c=(32.08%-38.06), 4d=(38.07%-44.05) and 5c=(44.06%-50%)}. the mean deviation (ď) value “30.0506% and 25.8194%” in roll 1 and 2 of table 4 falls within the rf “3e and 3d” respectively. hence the risk factors (rf) for the calculated mean deviation in table 4 all falls within 3c, 3d, 3e, 4b and 5b. 4.4 model validation and sensitivity analysis the ph profile from the experimental evaluation was compared with those predicted by the model at same spacing, resulting to close match as shown in figure 15. a sensitivity analysis carried out on the developed model predicted save residential area to be from 4.81 km from the flare location (figure 15). the model was tested at intervals of 0.1km starting from the flare site. the predicted distance for clean rain water (where ph is 5.6) is from 4.81km as shown in appendix 1 of this report. the results are in tandem with the assertion by (abassi et al., 2013; larssen et al., 2006), “acid rains and the pollutant that creates them are often transported far away by wind from their points of origin and the adverse effect of the pollutant reduces at some distance apart”. again, dispersion plays a vital role in which the plume of the emitted pollutant travels far from the point of generation to points they undergoes some form of chemical reactions. the extent they travel is a function of the pollutants dispersion coefficient. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 20 published by scholink inc. figure15. model validation figure 16. boundary between polluted and unpolluted zones for human habitation from flare areas 5. conclusion environmental risk of emitted co2 from flared associated petroleum gases was investigated in this research by harvesting 33 samples of rain water within 2km radius from the bund wall of flares. the evaluated ph was analysed by standard percentage deviation (spd) and quantitative risk matrix (qrm) evaluation methods. the present work was borne out of concern for more than two million (2,000,000) people residing at close proximity to flaring locations as reported in figure 2. flared gases in sensitive zones such as human residential and farm areas requires improved risk management by intensified monitoring, evaluation and designed mitigation plan. first, the study shows accumulation of co2 in the air space of the study area as disclosed by the flare tracker. this is evident in figures 2 and table 1 of this report. it revealed 809,300,000 mscf of flared gases for the 11 year period with a release of 43,000,000 tonnes of co2 in delta state alone. secondly, www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 21 published by scholink inc. it revealed decreasing acidification of acid rain away from the flare location as shown by the experimental data evaluations. finally, the model predicted 4.81km radius from flare locations for human habitation. it is worthy to note that carbon-dioxide, nitrogen oxide and sulphur oxide are the three main trans-atmospheric gases that precipitates rain water and making it acidic by increasing the concentration of hydrogen ion (h+). this work only addresses carbon-dioxide due to its deleterious and trans-boundary environmental concerns as a greenhouse gas. the research does not in any way undermine the effects of nox and sox as regards rain water acidification. the developed and validated risk model is a framework suitable for evaluation of safe residential zones in sensitive areas. the physicochemical parameters should be assessed based on the criticality of the risk factor (rf). the response of the risk screening model may presumably differ in other niger-delta states due to differences in the volume of emitted flare gases as shown in table 1. the study area was chosen because of high flaring volume on daily basis as compared to other areas. the remedy/panacea is to stop gas flaring and/or put control measures in place. one of the control measures is by initiating carbon capture and sequestration (ccs) projects in niger-delta region of nigeria, so as to meet the 2050 net-zero goals. hydrocarbon exploration, production and processing in niger-delta region of nigeria started since 1957, which has led to reservoir depletion and abandonment. some of the depleted reservoirs in niger-delta brown fields are presently termed marginal fields. nigeria has not less than 251 marginal fields (mobolaji & okoro, 2020), some of which are suitable for carbon capture and geological storage (ccgs), to reduce co2 emissions and to achieve 2050 carbon neutrality goal. besides saline aquifers, the depleted gas or oil reservoirs are proven to be suitable for implementation of co2 geo-sequestration in enhanced gas recovery or enhanced oil recovery. umar et al. (2020), davis et al. (2022), assessed the potential for co2 geo-sequestration in niger-delta basin, using seismic and well information data from wells in agbada formation. the results were compared to formation basin screening criteria reported by (bachu, 2003; co2crc, 2008). the assessments rated niger-delta formation “very good” and “excellent” depending on the screened criteria and parameter. hence niger-delta formations are safe for geological storage of co2. acknowledgement the authors wish to thank petroleum technology development fund (ptdf) of nigeria, for the studentship and the inputs of petroleum and gas research group of university of salford, manchester, united kingdom. declaration of conflicting interests the author(s) declared no conflicts of interest with respect to the research and publication of this article. www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 22 published by scholink inc. references abbasi, t., poornima, p., kannadasan, t., & abbasi, s. a. 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(1982). water supply and sanitation in developing countries. ann arbor science. ann arbor, michigan. singh, a., & agrawal, m. (2007). acid rain and its ecological consequences. journal of environmental biology, 29(1), 15. umar, b. a., gholami, r., nayak, p., shah, a. a., & adamu, h. (2020). regional and field assessments of potentials for geological storage of co2: a case study of the niger delta basin, nigeria. journal of natural gas science and engineering, 77, 103195. https://doi.org/10.1016/j.jngse.2020.103195 villa, v., paltrinieri, n., & cozzani, v. (2015). overview on dynamic approaches to risk management in process facilities. chemical engineering transactions, 43, 2497-2502. xuan, c., xiaoran, s., zhaoji, s., jiaen, z., zhong, q., huimin, x., & hui, w. (2021). analysis of the spatio-temporal changes in acid rain and their causes in china (1998-2018). journal of resources and ecology, 12(5), 593-599. https://doi.org/10.5814/j.issn.1674-764x.2021.05.002 https://doi.org/10.20935/al4646 https://doi.org/10.1007/s10669-007-9007-x https://doi.org/10.1088/1755-1315/753/1/012029 https://doi.org/10.1016/j.jngse.2020.103195 https://doi.org/10.5814/j.issn.1674-764x.2021.05.002 www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 25 published by scholink inc. appendix 1 results of sensitivity analysis on model b0 bi distance, xi (km) rain water acidity, p.h 0.1856 4.7018 2.0 5.0730 0.1856 4.7018 2.1 5.0916 0.1856 4.7018 2.2 5.1101 0.1856 4.7018 2.3 5.1287 0.1856 4.7018 2.4 5.1472 0.1856 4.7018 2.5 5.1658 0.1856 4.7018 2.6 5.1844 0.1856 4.7018 2.7 5.2029 0.1856 4.7018 2.8 5.2215 0.1856 4.7018 2.9 5.2400 0.1856 4.7018 3.0 5.2586 0.1856 4.7018 3.1 5.2772 0.1856 4.7018 3.2 5.2957 0.1856 4.7018 3.3 5.3143 0.1856 4.7018 3.4 5.3328 0.1856 4.7018 3.5 5.3514 0.1856 4.7018 3.6 5.3700 0.1856 4.7018 3.7 5.3885 0.1856 4.7018 3.8 5.4071 0.1856 4.7018 3.9 5.4256 0.1856 4.7018 4.0 5.4442 0.1856 4.7018 4.1 5.4628 0.1856 4.7018 4.2 5.4813 0.1856 4.7018 4.3 5.4999 0.1856 4.7018 4.4 5.5184 0.1856 4.7018 4.5 5.5370 0.1856 4.7018 4.6 5.5556 0.1856 4.7018 4.7 5.5741 0.1856 4.7018 4.8 5.5927 0.1856 4.7018 4.9 5.6112 0.1856 4.7018 5.0 5.6298 0.1856 4.7018 5.1 5.6484 www.scholink.org/ojs/index.php/ees energy and earth science vol. 7, no. 2, 2024 26 published by scholink inc. 0.1856 4.7018 5.2 5.6669 0.1856 4.7018 5.3 5.6855 0.1856 4.7018 5.4 5.7040 0.1856 4.7018 5.5 5.7226 0.1856 4.7018 5.6 5.7412 0.1856 4.7018 5.7 5.7597 0.1856 4.7018 5.8 5.7783 0.1856 4.7018 5.9 5.7968 0.1856 4.7018 6 5.8154 energy and earth science vol. 6, no. 2, 2023 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 1 original paper detection of ring structures and their surrounding tectonic pattern in south-algeria, north-mali and northniger based on satellite data barbara theilen-willige 1 1 technische universität berlin (tub), faculty iv (retired), berlin, germany received: march 21, 2023 accepted: march 30, 2023 online published: april 25, 2023 doi:10.22158/ees.v6n2p1 url: http://dx.doi.org/10.22158/ees.v6n2p1 abstract this study is focused on the detection of circular features with different sizes, origins, and state of erosion as well as on their surrounding tectonic pattern based on different satellite images of southern algeria, northern mali and northern niger. sentinel 2and landsat 8/9-images and sentinel 1and alos l-band phased array synthetic aperture radar (palsar)-radar data help to identify larger ring structures and smaller circular features, most of them related to magmatic intrusions into the subsurface, but also to cosmic impacts, with varying ages and state of erosion. some of them seem to be unknown so far as they are partly covered by aeolian sediments and become only visible on radar images. digital elevation model (dem) data and the dem derived morphometric maps support these investigations in a geoinformation system (gis) embedded environment. some of the ring structures are only visible on morphometric maps, traced by circular arrangements of slope gradients or concentric drainage patterns. the large, circular structures and the smaller circular features such as volcanic features (cinder cones, calderas, maars, impact craters) were digitized and merged in a gis with available geologic information. keywords ring structures, structural analysis, remote sensing, s-algeria www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 2 published by scholink inc. 1. introduction although a large amount of research has been carried out related to the geologic history and structural and tectonic inventory in southern algeria and adjacent areas (liégeois et al., 2005; azzouni-sekkal et al., 2007; fezaa et al., 2010; yahiaoui et al., 2014; bouzid et al., 2015) combined evaluations of different satellite data integrated into a geoinformation system (gis) are investigated, whether they can contribute to further additional geologic knowledge especially the combination of landsat 8 and 9 thermal band-, and sentinel 2 optical images, and sentinel 1-, alos palsarand sir-c-radar images allows the detection of surface-near structures (paillou et al., 2006). after evaluations of optical and radar satellite images and digital elevation data from southern algeria, northern mali and northern niger it became obvious, that there are some circular structures visible on the satellite images and on morphometric maps that were neither documented on available geologic maps, nor described in the geologic literature and, thus, seem to be unknown so far. the reasons for this vary according to the specific situation. some structures are buried underneath younger sediments and extended aeolian covers and not visible in the field, but still on satellite radar data because of the concentric arrangement of the drainage pattern or ring-shaped tonal anomalies on the images. therefore, this study aims to contribute to the systematic detection and inventory of ring structures and their adjacent tectonic pattern, as far as possible based on remote sensing and geoinformation system (gis) methods. the combination of different remote sensing data is used in the scope of this study to derive an overview of structural information and focus on an inventory of circular features of different sizes and origins and their surrounding tectonic pattern. such an inventory is important for example for hydrogeologic investigations as the groundwater flow is influenced by those structures because of permeability changes and for the mining and energy industry. for example, larger ring structures have an impact on multi-aquifer groundwater flow in the different groundwater levels. the larger fault systems and geologic structures such as dikes affecting the groundwater flow should be mapped carefully using the potential of thermal and radar satellite data as far as possible for this purpose. the long and thick, low-permeability dikes often act as barriers for the topography-driven groundwater flow. as mineral occurrence and deposits of economic value are often related to ring structures evaluations of satellite data might be of use for further detailed exploration. another reason for the detailed inventory of circular structures is the monitoring of potential geohazards. the position of larger ring structures related to plutons seem to have an influence on earthquake activity (theilen-willige, 2022). the different circular forms created by volcanic activity might be a risk for the land use and infrastructure, even in this arid environment with a low population density. not only the smaller eruptions have to be considered, but also the numerous dikes along fault zones and zones of weakness along structures. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 3 published by scholink inc. another example for the importance of geohazard monitoring is the collapse of sinkholes in karst areas affecting the safety of infrastructure. among the geohazards cosmic impacts of a larger meteorites or even asteroids have to be taken into account as well. the documented impact craters in algeria, mali and niger are proof of this potential risk in the geologic history. the earth impact database (eid) created by the planetary and space science centre (passc), canada, comprises a list of confirmed impact structures from around the world on land surfaces. to date, there are 190 confirmed impact structures in the world-wide database. it can be assumed that with ongoing research further impact craters will be discovered, some of them may be in the scope of this study. the low settlement density and land use restricted to water availability in this arid environment allows the conservation of craters, although often covered by aeolian sediments. special attention is focused on smaller, bowl-shaped craters that can be related to volcanic maars and calderas, karst depressions or impact craters. the next figure shows an overview of cosmic impact craters in the investigation area covering algeria and n-mali and n-niger (figure 1). figure 1. overview of documented impact craters in algeria. n-mali and n-niger based on the planetary and space science centre (passc), canada, impact crater data base www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 4 published by scholink inc. 2. geographic and geologic overview the investigation area includes the hoggar mountains in s-algeria with height levels up to 2900 m, the air mountains in n-niger reaching height levels up to 2000 m and the adrar des iforas in ne-mali with height levels between 800-900 m (figure 2). the climate is characterized by an arid environment with a hot desert climate. the hoggar massif in algeria is associated with exposed pan-african basement extending over an area greater than 500 000 km 2 (english et al., 2016), belonging to the tuareg shield composed of terranes. most of the tuared shield is situated in algeria (hoggar) and extends in the sw into the adrar des iforas in mali mountains and in the se into the air mountains in niger. the hoggar mountains form the main part of the tuareg shield, which principally comprises archaean/palaeoproterozoic and neoproterozoic terranes, composed of precambrian lithologies and unconformably overlain by subhorizontal palaeozoic sediments. the tuareg shield amalgamated during the late neoproterozoic pan-african orogeny as a result of the convergence of the west african craton (wac) and the saharan craton. the major structural domains of the tuareg shield are the “polycyclic central hoggar” to the east and the “western hoggar”, or “pharusian belt”, to the west (kourim et al., 2014). the terranes collided, welded and moved along subvertical shear zones to be finally squeezed between the west african craton to the west and the saharan metacraton to the east (azzouni-sekkal et al., 2003). figure 2. height level map of the investigation area based on gebco elevation data www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 5 published by scholink inc. geochronological results demonstrate that the eastern hoggar had not stabilized by c. 730 ma, but was subjected to a late ediacaran tectono-magmatic episode at c. 575-555 ma. this episode is younger and unlinked to the pan-african orogeny that occurred further west in the tuareg shield (fezaa et al., 2010). a first stage comprised the accretion of oceanic island arcs on these cratons and on microcratons during the period 900-680 ma. relics of these terranes, including ophiolites and eclogites, are preserved as thrust sheets on more rigid bodies (liégeois et al., 2003, 2008). the second stage was the regional northerly tectonic escape of the tuareg terranes due to oblique collision with the wac. during that stage, the metacratonization of the central hoggar microcontinent occurred, the squeezing of this rigid body, which was torn into several moving blocks. during the main pan-african phase (625-580 ma) the central hoggar microcontinent was dissected by n-s-oriented mega-shear zones that induced several hundreds of kilometers of relative displacement and allowed the emplacement of high-k calc-alkaline batholiths. smaller movements continued till 525 ma, accompanied by the emplacement of subcircular plutons with alkaline affinity. linear lithospheric delamination beneath these mega-shear zones may occur under such circumstances, allowing a drastic increase in heat flow and melting of the crust. post collisional and anorogenic high-level alkaline plutons are aligned on the same megashear zones, particularly along craton margins (liégeois et al., 2003; fezaa et al., 2010). figure 3 provides a geologic overview of the main geologic units according to the data provided in the web portal onegeology by the british geological survey british geological survey (bgs). figure 3. geologic overview of the tuareg shield according to the 1:10m-scale geological map of africa-bgs, 1:5,000,000 scale, downloaded from the onegeology, http://portal.onegeology.org/onegeologyglobal/ www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 6 published by scholink inc. recent volcanic activity from upper eocene to quaternary in age (35 to nearly 0 ma) is associated in the hoggar area with a crustal swell of 1000 km in diameter, probably the product of a mantle plume. in response to stress resulting from the africa-europe collision, volcanism may be generated by adiabatic pressure release of an uprising asthenosphere. the reactivation of preexisting shear zones and fractures generated during the pan-african (late neoproterozoic) orogeny (inducing limited linear lithospheric delamination at the lithosphere-asthenosphere interface along these mega-shear) played an important role. there are several volcanic districts located in hoggar, massif, n-mali and n-niger (figure 3, liégeois et al., 2003, 2008; yahiaoui et al., 2014; bouzid et al., 2015). the first volcanic event produced miocene composite flood lavas (plateau basalt) essentially made of alkali olivine basalts. trachytic and phonolitic plugs are associated with this phase zones (liégeois et al., 2003, 2005). 3. data and methods the interdisciplinary approach used in the scope of this research comprises evaluations of remote sensing data, geological, and topographic data, integrated into a gis environment. satellite imageries and digital elevation model (dem) data were used then for generating a gis data base and combined with different geodata (infrastructure, land use) and available geologic maps. infrastructural and land use shapefiles from algeria were downloaded from the geofabrik’s download server. digital elevation model (dem) data from the shuttle radar topography mission (srtm), and aster dem data (both with about 30 m spatial resolution) are covering the whole investigation area. the advanced land observing satellite-1 (alos), phased array type l-band synthetic aperture radar (palsar) from the japan aerospace exploration agency (jaxa) provided data with 12.5 m spatial resolution, however, not a complete coverage. the satellite data were downloaded from open sources such as the usgs/earth explorer, the sentinel hub/esa, and the alaska satellite facility (asf). 3.1 digital image processing of different optical and radar satellite data satellite data were processed and evaluated such as sentinel 1-c-band, synthetic aperture radar (sar) and alos palsar l-band data and optical sentinel 2 images, and landsat optical data (landsat tm and landsat 8 and 9 of the operational land imager-oli) using digital image processing software as the sentinel application platform (snap)/esa and envi/l3harris geospatial solutions as well as the geoinformation systems arcgis/esri and qgis. digital image processing of landsat 5 thematic mapper and landsat 8/9-the operational land imager (oli) data was carried out by merging different red green blue (rgb) band combinations with the panchromatic band 8 to pan-sharpen the images. three color composites were generated for the purpose of lithological zones mapping. especially, when combing the thermal bands of optical satellite data in a rgb image structural features are enhanced due to brightness differences. when analyzing satellite data traces of structures such as faults, folding and www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 7 published by scholink inc. domes are often clearly visible on satellite images. by using the band combination of 2, 7 and 10 of landsat 8/9 even deeply eroded ring structures can become visible as demonstrated by the example below from n-mali (figure 4). snap from esa provided the tools as well for the processing of radar data. synthetic aperture radar (sar) space-borne satellites operate by using microwave radiation with a frequency in a range of wavelengths, for example, the l-band (23 cm-1.30 ghz and 24 cm-1.25 ghz), c-band (6 cm-5.0 ghz), (mansour et al., 2022). l-band radar coverage was acquired by the jers-1 satellite of the japanese space agency (jaxa), c-band coverage by the sentinel 1 mission of esa. sar imagery can differentiate topographic variation with a high spatial resolution. radar imagers send out pulses of radio waves and collect the return signals after the waves were reflected of surfaces. the smoothness, roughness, and density of a surface affect the return signal. unlike optical instruments, which can only see the surface, radar can penetrate loose, dry materials such as sand sheets. alos/palsar l-band data are characterized by the optimal conditions of penetration in desert areas depending on the grain size, moisture, roughness of the surrounding geology and radar backscattering mechanism (mansour et al., 2022). in very dry soils, l-band sar (1.25 ghz) can intrude into the subsurface down to several meters. dark image tones are associated in general with flat areas because the incident radar signals were largely reflected from their “radar-smooth” surfaces in a mirror-like fashion away from the satellite antenna. figure 4. deeply eroded ring structure in n-mali visible on a landsat 9-scene (rgb, bands 2,7 and 10) www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 8 published by scholink inc. paleodrainage systems become visible due to their radar-smooth reacting sediment fill. thus, ring structures forming circular basins and depressions are often clearly detectable on radar images. the evaluation of radar data also helps in the building of more complete geological maps and in support of future water and mineral prospecting in arid regions (paillou et al., 2006, 2017). evaluations of cand l-band radar data prove to be of great value in the arid environment of the investigation area for the detection of geologic structures underneath aeolian covers. the visibility of ring structures on radar images depends in this arid environment mostly on the radar-illumination geometry and the surface properties. 3.2 evaluations of dem data mosaics were created based on the various dem data. in the scope of this study evaluations of morphometric maps derived from different dem data play an important role because ring structures sometimes can be traced more clearly on slope gradient, height level or drop raster maps than on other satellite images. optical, digital processed and enhanced satellite images are then correlated with the morphometric maps. figure 5 shows an example of a combined analysis of different satellite data. figure 5. combined and comparative analysis of different satellite data (optical data-sentinel 2, radar data-sentinel 1, srtm dem derived height level and slope map) for the detection of ring structures and-s-striking shear zones www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 9 published by scholink inc. 3.3 structural evaluation the shapefiles related to ring structures, lineaments, structural features, karst phenomena and volcanic features were digitized visually based on the different satellite images. especially sentinel 1 and alos palsar radar images reveal larger fault zones, for example by dislocations of lithologic units that can be digitized easily. in the scope of this study the following types of linear and curvilinear features were mapped: lineaments (as a neutral term for linear features without identifying their origin), probable fault zones, major fault zones and structural features. as traces of structural features are digitized the deformations due to stress such as synclines or anticlines, bedding structures, or traces of foliation in metamorphic rocks, often become visible as dense, arc-shaped, parallel lines. 4. inventory of ring structures and their surrounding structural pattern based on satellite data in the following chapters an overview of different circular structures and their expressions on satellite images is presented. in most cases their origin can be derived, however, in some cases clarifying of their origin remains for future investigations. the multiple overprinting of the structures during their geologic history often has led to a complex lithologic and tectonic development and composition. the structural pattern was analyzed, whereby the numerous dikes and dike swarms in the investigation area are of great value as the dikes indicate zones of “weakness” allowing the intrusion of magma. the spatial arrangement of mostly basic and ultrabasic dikes, their orientation and their density provide hints about the dynamic stress pattern. when digitizing the circular, structural features, it can be subdivided between several types of ring structures: a) traces of larger ring structures by a circular outline of the drainage pattern and circular tonal anomalies on the satellite images such as shown in figure 6, b) distinct expressed larger ring structures related to plutonic rocks forming often high-altitude domes and hills in the landscape with circular outline (sieber & theilen-willige, 1984), c) large circular basins with surrounding concentric hill ranges. some are forming bowl-shaped craters. the origin of this type of ring structure can be complex. one explanation might be volcanic activity leading to the development of a caldera. another one might be the erosion of a pluton with different resistivity of the lithologic units to erosion. along concentric faults of plutons magma often intruded later building ring dikes. d) smaller volcanic features such as volcanic cones, bowl-shaped craters (often related to maars and some to cosmic impact craters) and undefined smaller depressions such as deflation hollows. the main types of ring structures according to their sizes, geomorphologic appearance and origin are summarized in figure 6. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 10 published by scholink inc. figure 6. main types of sizes and origins of ring structures figure 7 provides an overview of the mapped circular features. of course, due to the large dune fields and aeolian covers this inventory based on satellite images cannot be complete. when combining the inventory of ring structures with lineament analysis and the known fault systems extracted from geologic maps, it becomes obvious that the larger ring structures are concentrated along the major shear zones (figure 7). post collisional and anorogenic high-level alkaline plutons are aligned on these mega-shear zones (black et al., 1979; liégeois et al., 2003, 2005, 2007). the nnw-sse, nne-ssw and n-s-oriented pan-african mega-shear zones are cross cutting lithologic units over hundreds of kilometers, up to 1000 km from middle algeria to northern niger and mali, visible even through the youngest sedimentary covers. these shear zones consist of parallel segments, partly moving relatively to each other. sometimes “graben-like” structures can be observed on the satellite images and on height level maps. recent tectonic uplift might be the reason (azzouni-sekkal et al., 2007). the large shear-zones were reactivated during later orogenic events and are still overworked by ongoing neotectonic movements, traced by abrupt displacements and magmatic intrusions, especially by parallel, linear dikes. the shear zones have been displaced and intruded by magmatic bodies forming dikes, maars and scoria cones, most of them of pleistocene and holocene ages (liégeois et al., 2005; yahiaoui et al., 2014). dikes and single, smaller volcanic scoria cones occur concentrated along the shear zones, as well as along larger ring structures. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 11 published by scholink inc. as these shear zones played an important role for the emplacement of magmatic bodies, a more detailed analysis of their structure was carried out using landsat 8 and 9, sentinel 2 and radar satellite data. figure 8 demonstrates the appearance of a shear zone near the southern border of algeria as visible on a landsat 9 rgb scene and figure 9 its structural evaluation. the varying geomorphologic properties of the shear zones depend on the regional geomechanical stress situation and lithologic composition. dikes intruded later into shear zones are forming linear ridges over long distances. reactivations of pre-existing fault structures under the current tectonic stress field have an impact on the development of dikes. the topographic cross section of the shear zone shown in figure 9 and reveals the almost flat environment, intersected by ridges and hill chains whenever dikes intruded into these zones of weakness (figure 10). however, most of them are buried underneath sedimentary covers. whenever the loose sedimentary covers or other lithologic layers comprise more than several meters, they cannot be detected even on l-band radar images. the fact that distinct expressed n-s-striking fault zones are clearly visible on the different satellite images, cross-cutting youngest sediments, as well as the intrusion of numerous dikes and scoria cones into the fault segments seems to support the assumption that the shear zones are still reactivated due to ongoing tectonic stress and movements. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 12 published by scholink inc. a) b) figure 7 a and b. structural evaluation combined with known fault zones pan-african mega shear zones, 1:10m-scale geological map of africa-sigafrique-bedrock age, french geological survey (brgm), france), downloaded from the onegeology portal www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 13 published by scholink inc. figure 8. landsat rgb, bands 2,7 and 10 scene of the shear zone and a distinct visible crater on the lower left of the scene. the wsw-ene oriented stripes are caused by wind erosion the topographic w-e-profile of the crater and the shear zone is presented in figure 10. the crater rises above the environment with more than 100 m. the height levels of the shear zone vary with the dike occurrence. another part of the pan-african shear zone in the central part of the hoggar massif between 4° and 5° longitude is revealed by alos palsar l-band data (figure 11 a-d). the parallel segments can be detected clearly. dikes are visible as very light lines along the shear zone due to their strong radar backscatter. in the volcano-tectonic regions of s-algeria, n-mali and n-niger, dike propagation from shallow magmatic chambers is controlled by the interaction with the local and regional stress fields, whereas their variations result from a combination of factors such as the geometry of pressurized magma chambers and the local geologic structure and the pre-existing fractures. when dike swarms are associated with flood basalts, their full extent and distribution are often difficult to assess because of a lack of exposure (hou, 2011). dike systems are typically hidden beneath volcanic piles or youngest sedimentary covers. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 14 published by scholink inc. figure 9. structural evaluation of the scene in figure 9 figure 10. w-e-topographic cross section of the shear zone and the crater (left side) based on srtm dem data www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 15 published by scholink inc. figure 11. a) and b). alos palsar l-band-scene (horizontal polarization hh) of a large, pan-african shear zone in the hoggar massif (red frame-enlargement shown in c and d) c) bingmap, and d) alos palsar-scenes visualizing dikes along the shear zone in the sw of the hoggar mountains an overview of dikes visible on the different satellite data is shown in the next figure (figure 12 a and b). the density of dikes was calculated to visualize those areas with a higher dike concentration (figure 12 a). the relatively higher dike density might be explained by uprising magma, that (by updoming the strata above) intensified fracturing processes and the reactivation of existing fault zones. dikes intruded into these zones of weakness. the highest density of dikes striking predominantly nnw-sse was detected in the adrar des iforas area in n-mali (figure 12 b) within the kidal-terrane, mainly comprising basement gneisses and calc-alkaline granitic plutons (bosch et al., 2016). a higher density of dikes could be used as an indicator for a relatively stronger tectonic stress in the affected area, at least at the time period of their development. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 16 published by scholink inc. figure 12 a. density concentration of dikes digitized based on the different satellite data figure 12 b. highest dike density in the adrar des iforas area in n-mali and main dike orientations www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 17 published by scholink inc. larger circular structures appear on the different satellite images as demonstrated in the next figures. 3.1 large ring structures related to plutons visible by traces of a circular outline because of the drainage pattern and circular tonal anomalies on the satellite images pluton emplacement mechanisms and surrounding conditions play an important role. the ring structures mostly related to alkaline magmatism (535-525 ma) as described by liégeois (2008) and the surrounding area are intruded later, mainly during the cenozoic reactivation (35-0 ma) by ring dikes, radial dikes and volcanic lava fields. the advantage of radar images becomes evident as the drainage network and structural features are clearly traced on the sentinel 1c-band radar image, whenever sheets of aeolian sediments are covering rock units as shown in figure 13 a and b. figure 13 a and b. comparison of a bingmap-scene with a sentinel 1 radar-scene indicating a buried ring structure in sw-algeria the advanced land observing satellite (alos) l-band synthetic aperture radar (palsar, japanese space agency-jaxa) complex single look (slc) images are characterized by the optimal conditions of penetration in these desert areas depending on the grain size, rare moisture, surface roughness, radar backscattering mechanism and radar illumination geometry (sieber & theilen-willige 1984; theilen-willige, 1986; mansour et al., 2022). the alos/palsar l-band waves can propagate www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 18 published by scholink inc. up to several meters, and, thus, may detect faults and structural features buried underneath loose sedimentary covers. the next figure (figure 14) demonstrates the better evaluation feasibilities of the l-band radar data to detect a circular structure in comparison with optical satellite data due to the traces of a concentric drainage pattern. thus, circular structures nearly invisible in the field and on optical satellite images because of sedimentary covers can be detected and mapped precisely on the radar image. the detection of the drainage system underneath younger sedimentary covers plays a role in case of rare flash floods in these arid areas because the surface water infiltrates through the loose sediment covers predominantly into the older drainage systems and, thus, contributes to groundwater storage. figure 14 a and b. world imagery-scene provided by esri (a) in comparison with the alos palsar l-band single horizontal polarized (hh) radar scene (b) indicating a multi-ringed, circular structure forming a basin with a diameter of about 8 km and a concentric drainage pattern in se-algeria another example is presented in figure 15 a, b, c and d by comparing optical satellite data with the alos palsar l-band (single horizontal polarized-hh), radar scene showing traces of a multi-ringed structure in south-algeria with a diameter of about 12 km. whereas the optical satellite data such as landsat (figure 15 c) reveal “stripes” caused by wind erosion in the main wind direction, the radar image allows a more detailed insight of the structural setting. the origin of this structure can www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 19 published by scholink inc. be explained by an uprising magmatic body updoming the strata above and leading to ring faults that are traced by the drainage pattern on the radar scene in dark concentric lines (figure 15 b). however, this structure has a strong geomorphologic similarity with a complex cosmic impact crater as well by showing a central hill ring (central uplift?) surrounded by ring depressions and concentric hill ranges. there seems to be a ring graben outlining the structure. the ring structure was intersected later by dikes in the eastern part. this structure should be investigated in the field to get rock samples for mineralogic analysis to get more knowledge about its origin. figure 15 a-d. detection of a circular, complex structure in s-algeria based on different satellite data 3.2 larger circular basins and depressions the thermally emitted radiation or brightness temperature observed over deserts in algeria supports the detection of reflection anomalies using satellite-based data. when evaluating landsat 8 and 9 rgb images involving the thermal bands large circular basins with surrounding concentric hill ranges, often consisting of ring dikes, become clearly visible (figure 16). large basins with more than 10 km in diameter are intersected by younger, parallel dike intrusions and dike swarms. 3.3 smaller ring structures in volcanic areas different volcanic fields are situated in the hoggar mountains in south algeria in height levels up to 3,000 meters with the lava domes and lava sheets, maars and scoria cones rising above the surrounding terrain. the topographic highlands are composed of precambrian basement uplifted since the pliocene www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 20 published by scholink inc. and of overlying lava plateaus, domes and spines, scoria cones, and valley-filling lava flows. the scoria cones have similar morphologies, characterized by the formation of an external erosion cliff, 10 to 30 m high, carved in the ejecta. a pediment developed at the cliff base, about 100 m wide, surrounding the cones, often covered by aeolian sediments (yahiaoui et al., 2014). some are forming craters and maars. figure 16. landsat 8-rgb scene of ring-shaped basins (eroded alkaline domes) surrounded by ring dikes in south algeria the atakor massif is located at the center of the hoggar swell within the tuareg shield. it is characterized by volcanic activity during three discrete neogene igneous episodes, separated by fairly long periods of quiescence (azzouni-sekkal et al., 2003, 2007). the evaluation of optical and radar satellite data contributes to a more detailed knowledge of the deep-seated fault zones facilitating the uprise of magmatic intrusions. in the area of the atakor and tahalra volcanic field prominent w-e and n-s oriented lineaments are prevailing (figure 17, figure 18). the lavas lie on precambrian granitic and gneissic rocks (azzouni-sekkal et al., 2007). uprise of magma occurred predominantly where n-s striking, large shear zones are intersected by w-e oriented lineaments. whereas the occurrence of volcanic activities in the atakor and tahalra fields seem to be influenced by larger fault zones, the next examples of the egéré volcanic field, idlès, tamanrasset province, show the influence of pre-existing ring structures such as domes with concentric faults on the emplacement of younger magmatic bodies as well (figure 19 a and b). developmental sequences of intrusions can be observed. the concentric arrangement of scoria cones follows both, the ring faults and larger intersecting fault zones. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 21 published by scholink inc. figure 17. structural analysis based on optical and radar satellite images of the atakor volcanic field (landsat 9-rgb image in the background indicating lava fields in orange and yellow colors). the line direction (rose) diagram is calculated based on lineaments in the red indicated area figure 18. structural analysis of the talhara volcanic field based on satellite data www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 22 published by scholink inc. figure 19 a and b. sentinel 2-scene of the western part of the egéré volcanic field (a) with a concentric arrangement of the scoria cones and lava fields and (b) structural evaluation of the sentinel 2-scene 3.4 smaller cosmic impact craters most of the documented known impact craters in the investigation area are smaller, bowl-shaped, simple impact craters such as the talemzane crater in n-algeria (figure 20). the talemzane crater is embedded in in senonian or eocene limestones and features an up to 70 m high rim. limestones are strongly fractured, upturned, and -in the upper rim-overturned. large, ejected blocks of limestone are scattered around the outside of the crater. breccia dikes are intersected by the crater wall, and detrital or reworked monomict breccia is found at the crater floor near the rim. quartz is a rare constituent in the limestones, but lambert et al. (1980) reported high pressure modifications like planar elements in some quartz grains. these authors estimated the age of the structure at <3 ma because of the limited degree of erosion observed (reimold & köberl, 2014). www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 23 published by scholink inc. figure 20. sentinel 2-rgb-scene of the talemzane impact crater the next figure (figure 21 a) provides an overview of ring structures forming craters, most of them related to magmatic activity (maars, calderas). however, some of them might be related to cosmic impacts. figure 21 b shows the diameter of crater-shaped ring structures, most of them with a diameter of about < 1 km, up to 1-2 km. when evaluating the different satellite data further craters were identified that are assumed to be created by a cosmic impact due to their similarities to the known impact craters and should be recommended for more detailed mineralogical and geophysical investigations to verify their origin. examples of craters that might be formed by a cosmic impact and not documented so far are presented in the next figures (figure 22 and figure 23), a potential complex crater with a diameter of about 4 km in figure 24. as mineral deposits are often linked to these types of ring structures (reimold & koeberl, 2005; osinski et al., 2012), more detailed investigations would make sense. the evaluation of different satellite data helps to focus costand time-intensive field research. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 24 published by scholink inc. figure 21 a. ring structures with crater morphology (red points) figure 21 b. diameters of crater-like ring structures 5. conclusions evaluations of different satellite data, enhanced with digital image processing methods, allow a more detailed and systematic inventory of circular structures, their different types, sizes and their surrounding tectonic pattern, even the detection of so far unknown ring structures. when analyzing the different satellite data, it becomes obvious that majority of the larger ring structures can be identified and correlated with available geologic information, whereas the smaller circular features (with exception of those situated within volcanic areas) are sometimes difficult to determine regarding their origin. nevertheless, the inventory of circular features based on satellite images will support further investigation in the field by providing a data base for focused field research. in the arid environment of the investigation area alos palsar l-band data were especially useful for this purpose because of the penetration capability of long-wave radar signals into dry, loose sedimentary covers. www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 25 published by scholink inc. figure 22 a and b. landsat 9and sentinel 1-scene of a potential impact crater in s-algeria figure 23. sentinel 2-scene of a potential eroded impact crater site in se-algeria, a ring structure with a diameter of about 2 km, embedded in paleoproterozoic calc-alkaline plutonic and anatectic layers and neoproterozoic to ordovician sedimentary layers (according to cgmw-brgm 1:10m geological map of africa,-3rd edition) www.scholink.org/ojs/index.php/ees energy and earth science vol. 6, no. 2, 2023 26 published by scholink inc. figure 24. satellite-scenes of a potential complex impact crater in s-algeria with a central elevation (?) acknowledgement the author is grateful for the input and support of the editor and team of energy and earth science and the reviewers. references alaska satellite facility (asf). 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(2014). impact structures in africa: a review. journal of african earth sciences, 93(2014), 57-175. https://doi.org/10.1016/j.jafrearsci.2014.01.008 reimold, w. u., koeberl, c., gibson, r. l., burkhard, o., & dressler, b. o. (2005). economic mineral deposits in impact structures: a review. in c. koeberl, & h. henkel (eds.), impact tectonics. impact studies, 6, 479-552. https://doi.org/10.1007/3-540-27548-7_20 sieber, a., & theilen-willige, b. (1984). comparative geologic analysis of landsat and sir-a-images of the adrar des iforas area in mali. in conference: proceedings of igarss’ 84 symposium (27-30 august 1984, ref. esa sp-215 (published by esa scientific & technical publications branch in august 1984, strasbourg), pp. 237-240). theilen-willige, b. (1986). satelliten-radaraufnahmen als hilfsmittel bei der erfassung von entwässerungssystemen in nordafrika und vorderasien. zeitschrift der deutschen geologischen gesellschaft (z.dt.geol.ges), 137(1), 363-377. https://doi.org/10.1127/zdgg/137/1986/363 theilen-willige, b. (2023). inventory of ring structures in nand w-morocco based on satellite data. european journal of environment and earth sciences, 4(1), 34-45. https://doi.org/10.24018/ejgeo.2023.4.1.364 usgs earth explorer. (n.d.). retrieved from https://earthexplorer.usgs.gov/ yahiaoui, r., dautria, j. m., alard, o., bosch, d., azzouni-sekkal, a., & bodinier, j. l. (2014). a volcanic district between the hoggar uplift and the tenere rifts: volcanology, geochemistry and age of the in-ezzane lavas (algerian sahara). journal of african earth sciences, 92, 14-20. https://doi.org/10.1016/j.jafrearsci.2013.12.001 https://doi.org/10.1016/0040-1951(94)90208-9 https://doi.org/10.1016/j.icarus.2012.08.030 https://doi.org/10.3390/w9030194 https://doi.org/10.1016/j.jafrearsci.2006.05.006 https://doi.org/10.1016/j.jafrearsci.2014.01.008 https://doi.org/10.1007/3-540-27548-7_20 https://doi.org/10.1127/zdgg/137/1986/363 https://doi.org/10.24018/ejgeo.2023.4.1.364 https://doi.org/10.1016/j.jafrearsci.2013.12.001 microsoft word ees-v3n1-p26 energy and earth science vol. 3, no. 1, 2020 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 26 original paper multi-phase manganese mineralization in the noamundi synclinorium, east indian shield d. chakraborty1* & t. k. baidya2 1 ex-csir research fellow, department of geological sciences, jadavpur university, kolkata, india 2 professor (retd.), department of geological sciences, jadavpur university, kolkata, india * d. chakraborty, ex-csir research fellow, department of geological sciences, jadavpur university, kolkata, india received: april 9, 2020 accepted: april 17, 2020 online published: may 7, 2020 doi:10.22158/ees.v3n1p26 url: http://dx.doi.org/10.22158/ees.v3n1p26 abstract manganese mineralization associated with phyllites in and around joda, odisha belongs to the iron ore group of noamundi basin and is a part of jamda-koira belt of east indian shield. the present study area comprises low to medium grade tectonites containing economic resources of both iron and manganese. present study is concentrated on manganese mineralization. field study and petro-mineralogical observations reveal syngenetic character of manganese ores comprising lowt higher oxides viz. pyrolusite, cryptomelane, manganite as major mn-minerals along with hight lower oxides viz. jacobsite, bixbyite, braunite and hausmannite as minor mn-minerals. the mn-ore bodies and associated phyllites have undergone multiple phases of deformation and metamorphism followed by hydrothermal and supergene processes. four deformational phases have been deciphered during field study. geochemical analyses of ores and phyllitic host rocks show high values of al2o3, tio2, ba, co, ni, cr, cu, sc, v, as, zn but depletion of sr, yb, sm, nb. geochemical data infer ores to be a recycling product originally derived from a mafic crustal source of tholeiitic character. age data obtained from sm-nd ratio of two rock samples are 3.46 ga and 2.79 ga. present work provides a critical assessment on the multiphase mineralization of manganese ores. keywords manganese, recycling, joda, noamundi, india www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 27 published by scholink inc. 1. introduction the present study area, in and around joda, comprises the precambrian iron ore group (iog) of the noamundi basin, odisha, a part of the mesoarchean greenstone belt (3.5-3.0 ga) viz. jamda-koira belt of the east indian shield (eis). low to medium grade tectonites containing economic resources of both iron and manganese are themajor rock types of the regional noamundi synclinorium. manganese ores, in this area (lat: 21°46’ 22°10’n; long: 85°06’ 85°35’ e) are hosted mainly by tuffaceous phyllites of the iog (3.3-3.1 ga, saha et al.1988) in the eastern limb of the noamundi synclinorium, whereas iron ores are associated with mainly quartzites and phyllites in some places. the principal mineralized areas of manganese are bichakundi, bamebari, khondband, guruda and joribar in and around joda. archean manganese and iron mineralization in greenstone belts are reported from limited occurrences viz. the rio das velhas deposit of brazil (machado & carnerio, 1992; teixeira et al., 1996; martin et al., 1997), the barberton greenstone belt of south africa (de wit et al., 1980; anhaeusser & wilson, 1981), the yilgarn and pilbara blocks of western australia (condie, 1981; hallberg & glikson, 1981), the sebakwian-bulawayan-shamvaian belt of zimbabwe (myers & kröner, 1994; windly, 1982), the superior and slave provinces of abitibi belt, canada (goodwin, 1973; dimroth et al., 1982), the isua formation of greenland (gross, 1986; schidlowski, 1988), the bababudan and chitradurga belt of south india (ramakrishnan et al., 1976; chadwick et al., 1981a, b) and the iron ore group (iog) of the east indian shield (roy, 1981; saha, 1994, ghosh, et al., 2015a, b). the greenstone rocks of the present area belong to the iog, which overlies the singhbhum granite type-a and underlies the singhbhum granite type-b (saha et al., 1988). from the field study, it is observed that the manganese ore bodies exhibit their conformable character with the host phyllites which are often laminated and compositionally banded. manganese ore bodies are mainly of four different types viz. massive, banded, colloform (pisolitic/botryoidal/reniform) and brecciated. from petrographic studies, it is revealed that manganese ore is characterized by minerals of low temperature higher oxides such as pyrolusite, cryptomelane, manganite as well as high temperature lower oxides such as braunite, bixbyite, jacobsite, hausmannite. the present area bears evidence of regional metamorphism from upper green schist facies to lower amphibolite facies with four phases of tectonic deformation. basedupon analytical data of major, minor, trace and rare earth elements, enrichment of al2o3, tio2, cr, sc, v, ba, co etc. is observed in both manganese ores and associated host rocks along with positive correlation between alumina-titania and alumina-magnesia. manganese and iron mineralization in and around joda, kendujhar district, odisha, have been studied by jones (1934), dunn and dey (1942), roy (1968), banerji (1977), chakraborty and majumdar (1986), ghosh et al. (2015) covering different ore geological aspects. despite the aforesaid work, there is ample scope for the work on mn-mineralogy, geochemistry, geochronology and ore genesis which the present paper tries to incorporate. manganese mineralization in the joda-noamundi sector reveals recycling of manganese through different phases of tectonic deformation and metamorphism followed by later hydrothermal and supergene processes. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 28 published by scholink inc. 2. regional geology and stratigraphy the east indian shield (eis) (21°25°n lat. and 85°-88°e long) comprises two precambrian cratonic blocks viz. the northern high grade metamorphic chhotanagpur granulite gneiss terrain and the southern low grade metamorphic singhbhum granite greenstone terrain, which are separated by the singhbhum orogenic belt containing dalma lavas and singhbhum group of rocks. figure 1 shows the geological map of the eis. the singhbhum granite greenstone terrain is bounded by singhbhum shear zone (200 km long) in the north and separated from the proterozoic eastern ghat mobile belt by sukinda thrust in the south. the generalized stratigraphic succession in this singhbhum craton after saha et al. (1988) is given in table 1. the singhbhum cratonic block comprises two archean greenstone belts viz. jamda-koira belt along with noamundi basin on the west and gorumahisani-badampahar-daitari belt on the east. the joda area with mn-mineralized zones belongs to the jamda-koira belt and located in the eastern limb of the noamundi synclinorium. both manganese and iron ores are closely associated with banded iron formation (bif), metamorphosed volcanic and sedimentary rocks of the iog. the basement rock of the iog basin is dominantly singhbhum granite (type-a). the mesoarchaean succession in the singhbhum crustal province begins with the iron ore group (iog), characterized by banded iron formations (bif), clastic sedimentary rocks and minor carbonates (chakraborty & majumder, 1986; saha, 1994; bhattacharya et al., 2007; mukhopadhyay et al., 2008). iog rocks are low grade metamorphosed and intruded by younger singhbhum granite (type-b). bonai-keonjhar iron-manganese belt (lat: 21°40’ and 22°15’ n and long: 85°00’ and 85°35’ e) in the iog forms a 60 km long & 25 km wide synclinorium (noamundi synclinorium), referred to as “iron-ore horse shoe” plunging variously to north and north east. the corresponding anticlinal core in the western part of the noamundi synclinoriumis mainly occupied by the 3.3 ga bonai granite (saha, 1994). bif, which is an important volcano-sedimentary rock formation of the archean greenstone belt, broadly defines the outline of the synclinorium, are almost continuously exposed along the margin, while manganese ore bearing shales occur within the core region of the fold. the entire region displays the effect of superposed folding on two near perpendicular axes, the generalised trends being nne-ssw & wnw-ese to nw-se (gsi report on manganese ore, 2011). mn-mineralization in and around joda has taken place in joda, bichakundi, khondband, guruda, joribar and bamebari areas. 3. previous work manganese mineralization in the noamundi-jamda-koira belt is a very conspicuous feature in close association with iron ores. spencer (1948) considers manganese ores hydrothermal in origin but sen (1951) regards them to be submarine volcanic origin. engineer (1956), prasad rao and murty (1956) consider the manganese ores products of the replacement of shales and quartzites by manganiferous solutions. basu (1969) considers these ores syngenetic but modified by epigenetic concentration. basu (1969) and roy (1978) describe bedded manganese orebodies interstratified with shale (often www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 29 published by scholink inc. tuffaceous) and sometimes co-folded with it from kalimati, phagua, gurda block ii and the mahulsukha mine-areas in odisha (cf. roy, 1981). murthy and ghosh (1971) reported pyrolusite-cryptomelane-manganite-rhodochrosite bearing mn-ores in association with chert and dolomite beds and regarded the manganese minerals originally disseminated in the shales and later mobilized and concentrated at structurally favourable sites. banerji (1977) concluded that manganese ores formed later than the iron ores. subramanyam and murty (1975) and banerji (1977) suggest a volcanic source for the manganese deposits. banerji (1977) stratigraphically characterized iron-manganese mineralization in the jamda-koira belt as the noamundi group of much younger age (c.1500-1100 ma) with the following sequence (ascending order) lower shale (tuffaceous shale–phyllite), banded hematite jasper, upper shale (manganiferous shale, tuff and chert), basic intrusion, grinitic activity. sarkar and saha (1962, 1977) described manganese ore bodies intimately associated with unmetamorphosed shales (occasionally tuffaceous) and chert of the archean iog. according to roy (1981), mn-oxide deposits are intimately associated with unmetamorphosed shales (occasionally tuffaceous) and cherts of the precambrian iog rocks and the manganese ores are of dominantly lateritoid type having mainly pyrolusite and cryptomelane with local manganite. there are a number of manganese ore bodies within chert and/or shale as layers and lenses (banerji, 1977; mohapatra et al., 1996; mishra et al., 2006). mishra et al. (2006) classified the iog manganese orebodies into stratiform, stratabound, and lateritic types. the stratiform type has distinct lamination or banding, and is often co-folded with shale. the stratabound type is structureand shear zone-controlled and is often silicified. these ore bodies occasionally cross-cut the bedding planes of the host shale. 4. methodology samples of various types of ore and associated host rocks are collected from the open-pit mines and surrounding areas for geochemical analyses and isotopic studies. petro-mineralogical work includes study under transmitted and reflected light microscopes, x-ray diffraction (xrd) study, scanning electron microscopy (sem), energy dispersive x-ray (edx) and electron probe micro analyzer (epma). sem–edx analysis of polished ore thin sections is done using inca x-sight software under accelerating voltage 20 kv and probe diameter 2 μm. epm analysis is done using pixite software with an accelerating voltage of 15 kv, current of 12 na and beam size of 1 μm. major element, trace element and ree analyses of the ores and associated rocks are done by the australian laboratory services, queensland with a combination of xrf and icp-ms techniques after comminution of the samples to -300 mesh in contamination-free pulverizer. for the purpose of sm/nd isotopic study, two crushed rock samples are analyzed for their sm and nd abundances by isotopic dilution, and the isotopic composition of nd by mass spectrometry. the isotopic composition of nd is determined in static mode by multi-collector icp-mass spectrometry. all isotope ratios are normalized for variable mass fractionation to a value of 146nd/144nd=0.7219 using the exponential fractionation law. sm isotopic abundances are measured in static mode by multi-collector icpmass spectrometry, and are normalized www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 30 published by scholink inc. for variable mass fractionation to a value of 1.17537 for 152sm/154sm also using the exponential law. sm/nd isotopic studies are done by icp-sfms at the canadian laboratory of the australian laboratory services. 5. mode of occurrence and structural disposition of manganese ores manganese ores occur as massive, thinly laminated or lenticular stratabound bodies hosted by differently coloured (red, pink, yellow, brown, purple, smoky grey, etc.) phyllites which are kaolinised in many parts to different degrees. large deposits of manganese ores are being mined in bichakundi (near joda), khondband, bamebari, guruda and joribar areas in the eastern part of the noamundi synclinorium. in khondband and guruda areas manganese ore bodies are very closely associated with iron ores. the massive mn-ore bodies show typical colloform structures (often pisolitic and botryoidal). the ore bodies, in places, are co-folded with phyllites forming mesoscopic synforms and antiforms. in the joda area, manganese ore bodies are mainly hosted by phyllitic rocks with minor quartzites. the lenticular bands of manganese ore are conformable with the host phyllites. the phyllites are, in places, laminated, compositionally banded and often showing brecciated character (figure 2a). the laminated phyllites are light coloured and mainly composed of very fine-grained phyllosilicates with intermittent occurrence of ferruginous chert. the geological field work reveals manganese ore bodies to be of four different types viz. massive, banded, colloform (pisolitic/botryoidal/reniform) and brecciated. in the quarry section, manganese rich ore pockets are overlain by ochre which in turn is capped by lateritic horizon (figure 2b). at places, a high degree of strain has produced folds with rootless intrafolial character (figure 2c). the associated iron ore bands comprise mainly hematite or martite with variable amounts of goethite and minor amounts of magnetite and siderite. hematite-rich iron ores often show typical bif character accompanied by strong deformational events (figure 2d). the gangue material is principally composed of cherty silica (in the form of jasper or quartzite) and kaolinitic clay. the manganese ores and associated host rocks bear the evidence of multiphase tectonic deformation. the f1 and f2 folds are more or less isoclinal and axial plane dipping towards nw or se. the f3 fold is transverse and superposed over f1 and f2 and is much more open in character with axial plane e-w in general. the major mn-ore bodies are mainly localized in the axial zones of the f2 folds (figure 2e), thin manganese ore bands are concentrated along the s2 axial plane (figure 2f). the f2 fold axis plunges 7⁰ to 40⁰ towards the nne or the sw with local variations towards the nnw, e and ene. manganese ore bands are also co-folded with the host phyllite forming mesoscopic synformal and antiformal structures (figure 2g & 2h). the f2 fold of the ore bodies can be categorized in class 2 of ramsay’s geometrical classification of folds (ramsay, 1967). the third phase of tectonic deformation (d3), having a transverse compressive stress direction in comparison with d1 and d2, produced open type of cross folds (f3) (figure2i) which in turn resulted in small dome and basin structures with axial culmination and depression. this corresponds to type-i interference pattern of ramsay (1967). rootless intrafolial fold of d1/f1 generation is also observed in the field (figure2c). the axis of f3 plunges 10⁰ to 62⁰ towards www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 31 published by scholink inc. wnw mainly with variations of w, nw and se. the d3 phase was further followed by a phase of faulting and shearing (d4) (figure 2j) which formed a number of sets of faults in this region among which at least three sets of faults are discernible in the field, the attitudes of which are as follows: i) 60⁰ to 85⁰ dipping towards w to nw. ii) 8⁰ to 10⁰ dipping towards se to ne. iii) 60⁰ to 65⁰ dipping towards the sw. the fault and shear zones are mostly in filled with pyrolusite-cryptomelane-chert association and fault breccias (figure 2k). although the mn ores are not uncommon along the s0 and s1 planes, the ores are primarily concentrated in the f2 hinge areas. thinning of the ore bands at the limbs and thickening of the same at the hinge are very frequent in the manganese ore mineralized zone. the folded ore bodies have two general axial trends ne to ene and sw to wsw. the axial planes of these folded ore bodies dip between 40⁰ and 72⁰ towards nw or se. in these areas, the ore bodies also plunge along the f2 fold axis (figure2l). 6. mineralogy and petrography of manganese ores study under microscopes (both reflected and transmitted light) reveals that the predominant manganese ore minerals are pyrolusite, cryptomelane and manganite. braunite, bixbyite, jacobsite and hausmannite occur mainly as minor phases. minor iron ore minerals like hematite/martite and goethite are also present. the associated gangue minerals include quartz, muscovite, biotite, kaolinite and glauconite. two generations of axial plane cleavage have been identified in the manganese ore. the first-generation cleavage (s1) is conformable with the compositional banding/bedding (s0) whereas the second-generation cleavage shows transgressive relation with s0 and s1 planes manganese ore gets mainly concentrated along the f2 hinge area (figure 3a). the micro-folded veins of pyrolusite forming f2 puckers exhibit their syn-kinematic character to d2 phase of tectonic deformation (figure 3b). bixbyite crystals showing brecciated character are mostly fragmented at the edges with matching boundaries. as a secondary mineral, pyrolusite partly replaces bixbyite and the edges of the bixbyite crystals are rounded up in a few places (figure 3c). jacobsite grain is found as scattered within the silicate rich groundmass (figure 3d). well-developed braunite crystal is exhibiting its resorbed grain boundary replaced by polianite crystals of later generation (figure 3e). bands of colloform structure at the interstitial spaces of banded ore clasts are also present (figure 3f) which contains altered braunite crystals of earlier generation. second generation of pyrolusite rich vein is closely associated with hematite rich matrix (figure 3g). hematite-goethite rich vein was formed at a late stage which is little bit folded at places (figure 3h). the possible weathering reactions deduced from textural studies are as follows: 2 bixbyite+o2=4 pyrolusite/polianite (figure 3c) 4 bixbyite+k++2o2+nh2o=cryptomelane (figure 3c) braunite+2o2=7 pyrolusite+sio2 (figure 3e) www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 32 published by scholink inc. 7. major element geochemistry the average silica content in ores and associated phyllites (except 93% in one sample of bamebari quartzite) are 9.07% and 45.68% respectively. the average alumina content in ores and phyllitic rocks are 7.49% and 26.65% respectively. the average tio2 content in phyllitic rocks is 2.96% with a maximum value up to 6.96%. the average mgo content is higher in phyllites (1.15%) than its average content in ore samples (0.22%). the average concentration of fe2o3 in associated host rocks, manganese-bearing ores and iron ores are 7.4%, 14% and 59.7% respectively whereas the average concentration of mno in host rocks, iron-bearing ores and manganese ores are 1.83%, 6.05% and >39% respectively. mno shows an inverse relationship with almost all the major oxides except p2o5. strong positive correlations among al2o3, tio2, cao are observed. the major element contents of manganese-iron ores, associated phyllites and quartzites are presented in table 2. 8. trace element geochemistry 41 trace elements are determined using icp-ms techniques in some manganese ore samples and associated rocks of joda. the data are presented in table 3. it is observed that the average concentration of trace elements cr, co, ni, cu, zn, as, ba are 219ppm, 52.7ppm, 100.5ppm, 40.5ppm, 94.6ppm, 19.62ppm, 689.95ppm which are relatively higher in comparison to their average crustal abundances. it is also observed that there are strong positive correlations between sc and al2o3 (figure 4a), v and al2o3 (figure 4b), cr and al2o3 (figure 4c), th and al2o3 (figure 4d), ga and al2o3 (figure 4e), nb and al2o3 (figure 4f). the average concentrations of sc, v are found to be 11.6 ppm, 101.1 ppm respectively; there is a relative enrichment of sc, v, cr in comparison with average zr & th. the average ba content varies from 205.6 ppm in host rocks to 1012.85 ppm in ores (maximum up to 2960 ppm) respectively. the average pb content varies from 10 ppm in host rocks and 26.8 ppm in ores respectively. the average cs content is 2.18 ppm and cs is probably derived from psilomelane-rich ore. the average rb content is 65 ppm, rb generally replaces k and is always associated with potash bearing minerals. chondrite normalized (after mcdonough & sun, 1995) trace element pattern of manganese ores and associated rocks shows positive co, as, rb, ba anomaly (figure 7). 9. rare earth element (ree) geochemistry the manganese ores and associated rocks of the joda area are analyzed using inductively coupled mass spectrometry (icp-ms) to determine the dispersion pattern of ree and their genetic implications. the ree concentration values are presented in table 4. the la content ranges from 2 to 44.2 ppm. the average concentration of ce is 25.71 ppm. the average contents of pr (3.358 ppm), sm (3.042 ppm), eu (0.874 ppm) are low in comparison to other lree. the average concentration of nd is 13.2 ppm and it is observed that in all the samples under consideration, the concentration level of nd is higher with respect to that of pr, gd and dy are showing maximum concentration in comparison to other elements of hree. the highest concentration of gd is 5.9 ppm and highest concentration of dy is 7.83 ppm. the total www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 33 published by scholink inc. content of hree (146.67 ppm) is very low in comparison to the total lree content (609.34 ppm). the average concentration of σhree in all the samples is found to be 14.667 ppm in comparison to that of σlree which is found to be 60.934 ppm. all ree results have been normalized with north american shale composite (nasc, haskin et al., 1968; figure 8a) and also with average upper continental crust (taylor & mclennan, 1981; figure 8b). both standard-normalized ree patterns exhibit similar trends. the diagrams depict an overall depletion of lree and relative enrichment of hree, an exception for an ore sample with diminished hree value that can be attributed to preferential leaching of hree by meteoric water in oxidized ores. the most significant feature of the ree pattern is the positive eu anomaly of the ores and associated rocks. the average eu/eu* and ce/ce* values are 1.16 and 0.8 respectively. in tio2-zr/(p2o5 *104) discrimination diagram (figure 9), there is a complete separation between the fields of tholeiitic and alkali basalts with alkali basalts plotting in the field of low zr/ p2o5 and high tio2. 10. sm-nd isotopic studies and age two rock samples are analyzed for sm and nd by isotope dilution. the details of the analytical results are given in table 5. model age for the sm-nd system is chosen for the purpose of present study as it can be calculated for an individual rock from a single pair of parent-daughter isotopic ratios. during model age calculations, one assumption is made about the isotopic composition of the reservoir from which the rock samples are ultimately derived. the age calculation of the two rock samples are carried out based on tdm (t-depleted mantle) model age as the initial 143nd/144nd ratios from precambrian terrains suggest that the mantle which supplied the continental crust has evolved since earliest times with an sm/nd ratio greater than that of chur (chondritic uniform reservoir). moreover, fractionation of the rock samples is considered negligible after its separation from the mantle source. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 34 published by scholink inc. table 1. the generalized chrono stratigraphic succession of the singbhum-orissa iron ore craton (after saha et al., 1988) newer dolerite dykes and sills c. 1600-950 ma mayurbhanj granite c. 2100 ma gabbro-anorthosite ultramafics c. 2100-2200 ma kolhan group unconformity jagannathpur lava dhanjori-simlipal lavas (c. 2300 ma) malangtoli lava quartzite-conglomer ate dhanjori group pelitic and arenaceous metasediments with mafic sills (c. 2300-2400 ma) singhbhum group unconformity singhbhum granite (type b) (phase iii) c. 3.1 ga mafic lava, tuff, acid volcanics, tuffaceous shale manganiferous shale and mn-ores (noamundi group of banerji, 1977), iron ore group banded hematite jasper, banded hematite quartzite with iron ores, ferruginous chert, local dolomite and quartzite sandstone nilgiri granite singhbhum granite (type a) (phase i and ii) c. 3.3 ga folding and metamorphism of omg and omtg bonai granite older metamorphic tonalitic gneiss (omtg) c. 3.775 ga older metamorphic group (omg): pelitic schist, quartzite, c. 4.0 ga para-amphibolite, ortho-amphibolite www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 35 published by scholink inc. table 2. major element oxide contents of manganese ores and associated rocks in joda area, odisha (in wt%) oxides d1 d2 d3 d4 d5 d6 d7 d8 d9 d10 d11 d12 d13 d14 fig tree shalesa moodies shalesb nascc acpsd sio2 60.05 53.07 55.35 30.07 92.8 3.63 5.7 0.71 7.7 3.55 57.96 27.44 20.24 12.16 60.49 59.32 64.82 66.9 al2o3 17.64 13.72 17.3 12.7 0.27 0.64 3.42 1.14 6.12 2 22.02 43.72 45.51 26.44 11.86 13.93 17.5 16.67 fe2o3 9.89 8.88 15.46 47.22 4.74 83 47.43 17.67 78.87 10.36 4.78 2.98 5.08 41.82 0.51 0.44 0.8 0.78 mgo 1.15 1.12 1.01 0.8 0.03 0.08 0.18 <0.01 0.05 0.26 1.12 2.19 0.31 0.22 8.56 7.36 5.7 5.87 cao 0.07 0.1 0.06 0.04 0.03 0.04 0.18 0.09 0.02 0.31 6.06 8.36 8.28 6.07 0.11 0.13 0.25 0.06 na2o <0.01 0.03 <0.01 0.01 <0.01 <0.01 0.02 0.01 <0.01 0.05 0.76 2.45 0.51 0.09 2.4 1.35 3.51 0.53 k2o 3.72 3.84 3.59 3.78 0.06 0.02 1.11 0.35 0.08 2.13 0.43 1.89 0.38 0.68 5.82 5.1 2.83 2.59 mno 0.16 11.1 0.03 0.21 1.06 1.36 27.2 >39 0.21 >39 0.03 0.04 0.43 1.27 2.45 4.87 3.97 4.97 tio2 1.48 1.35 1.4 1.82 0.02 0.03 0.22 0.03 0.53 0.05 1.79 4.81 6.96 4.09 1.04 1.76 1.13 1.5 p2o5 0.11 0.02 0.04 0.05 0.05 0.64 1.04 0.06 0.17 0.07 0.008 0.007 0.003 0.042 0.15 0.14 h2o 4.63 5.22 10.07 6.67 loi 5.11 5.24 5.07 2.92 0.35 10.75 12.08 11.04 6.62 12.53 4.84 5.76 12.2 6.96 6.69 5.75 note. *d1-d quarry phyllite; d2-bamebari phyllite; d3-h quarry phyllite, d4-khondband iron ore; d5-bamebari jasper quartzite; d6-h quarry manganese bearing iron ore; d7-bamebari iron-manganese ore; d8-khondband iron bearing manganese ore; d9-h quarry iron ore; d10-khondband manganese ore; d11-bamebari kaolinized phyllite; d12-h quarry kaolinized phyllite; d13-guruda phyllite; d14-khondband iron ore. afigtree group (3.4 ga) and bmoodies group (3.3 ga) of swaziland supergroup, s. africa (mclennan & taylor, 1983). cnorth american shale composite (gromet et al., 1984). daverage canadian proterozoic (aphebian) shale (cameron & garrels, 1980). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 36 published by scholink inc. table 3. trace element contents of mn-ores and associated rocks of joda area (in ppm) elements d1 d2 d3 d4 d5 d6 d7 d8 d9 d10 li 10 30 10 <10 10 <10 60 <10 <10 10 sc 24 18 25 17 <1 4 9 2 10 6 v 254 121 291 93 6 28 52 12 122 32 cr 430 200 600 300 10 140 60 10 420 20 co 8 42 3 11 5 10 98 60 <1 289 ni 64 160 55 14 19 183 294 27 39 150 cu 28 57 45 5 10 16 132 14 19 79 zn 18 93 21 15 13 163 289 56 39 239 ga 22.5 11.7 23.7 21.2 1.6 3.9 8 6 8 7.5 ge 5 <5 7 5 <5 <5 <5 <5 5 <5 as 5.3 5.1 3.6 4 8 5.2 133 6 18.4 7.6 se 0.3 1 0.3 0.4 <0.2 0.6 1.9 0.6 0.5 1.7 rb 142.5 88.8 138.5 163.5 2.2 0.8 32 7.4 3.2 71.9 sr 7.4 39.8 10.4 7 5.3 2.9 112.5 206 1.5 384 y 24.7 28 23.4 46 3.1 28.1 65 10.4 17.7 111.5 zr 186 131 169 318 3 6 32 8 84 12 nb 12.5 7.3 11.5 17.8 <0.2 0.4 1.9 0.5 5.1 0.5 mo <1 <1 <1 <1 1 <1 <1 <1 <1 <1 pd 0.003 0.004 0.004 0.003 <0.001 <0.001 0.001 0.002 0.002 0.002 ag <0.5 0.5 <0.5 <0.5 <0.5 <0.5 1.7 2.7 <0.5 2.5 cd <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 1 <0.5 <0.5 2 in 0.028 0.04 0.032 0.043 <0.005 0.012 0.028 0.007 0.03 0.022 sn 4 2 4 5 <1 <1 1 <1 1 <1 sb 0.17 0.05 0.18 0.63 0.05 0.34 0.12 0.21 0.18 0.18 te 0.02 0.03 0.03 0.08 <0.01 0.04 0.06 0.06 0.05 0.02 cs 3.75 3.47 3.81 2.48 0.08 <0.01 1.79 0.27 0.05 6.11 ba 206 438 154.5 979 23.9 42.6 301 1670 124.5 2960 hf 4.9 3.5 4.4 8.4 <0.2 0.2 0.8 0.2 2.3 0.3 ta 1 0.6 1 1.6 <0.1 <0.1 0.1 <0.1 0.5 <0.1 w 1 <1 1 2 1 <1 <1 <1 1 2 re <0.001 <0.001 <0.001 0.001 <0.001 <0.001 0.001 0.002 0.001 0.002 pt 0.0024 0.0038 0.003 0.0059 <0.0005 <0.0005 0.001 <0.0005 0.0017 <0.0005 au 0.001 0.001 0.003 0.001 <0.001 0.001 0.001 0.004 0.001 0.005 hg 0.005 0.044 0.017 0.059 <0.005 0.013 0.042 0.4 0.137 0.816 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 37 published by scholink inc. tl 0.1 0.13 0.04 0.08 <0.02 <0.02 0.09 0.56 <0.02 0.58 pb 6 18 14 17 <2 <2 21 56 10 55 bi 0.13 0.08 0.07 1.48 0.01 0.02 0.05 0.04 0.06 0.08 th 6.58 5.02 5.53 13.4 0.09 0.24 1.26 0.6 3.65 0.63 u 2.06 1.77 1.75 2.95 0.13 2.84 1.43 0.34 4.2 0.91 table 4. icp-ms analytical data for rees in mn-ores and associated rocks of joda area (in ppm) elements d1 d2 d3 d4 d5 d6 d7 d8 d9 d10 la 17.2 18.2 19.4 12 2 5.2 44.2 13.1 5.8 10.4 ce 27.4 38.7 18.4 32.9 2.8 7.1 57 55.4 7.8 9.6 pr 3.37 4.14 3.63 2.34 0.47 1.64 9.79 4.29 1.68 2.23 nd 12.6 15.4 14.2 8.5 1.7 7.3 37.6 16.3 7.5 10.9 sm 2.8 3.4 3.21 2.12 0.36 1.97 7.95 3.72 1.76 3.13 eu 0.7 0.95 0.92 0.61 0.09 0.64 2.27 0.84 0.64 1.08 gd 2.71 3.74 3.54 2.78 0.4 2.98 9 2.59 2.45 5.9 tb 0.49 0.59 0.56 0.59 0.06 0.5 1.36 0.42 0.37 0.98 dy 3.28 3.65 3.71 4.66 0.34 2.93 7.83 2.18 2.44 7.11 ho 0.75 0.78 0.76 1.16 0.07 0.61 1.6 0.35 0.55 1.81 er 2.43 2.29 2.33 4.17 0.19 1.68 4.33 0.84 1.75 5.99 tm 0.37 0.35 0.35 0.71 0.03 0.23 0.56 0.11 0.29 0.79 yb 2.47 2.22 2.34 5.35 0.17 1.44 3.38 0.7 1.87 4.46 lu 0.38 0.36 0.37 0.85 0.02 0.24 0.54 0.09 0.29 0.76 σlree 64.07 80.79 59.76 58.47 7.42 23.85 158.81 93.65 25.18 37.34 σhree 12.88 13.98 13.96 20.27 1.28 10.61 28.6 7.28 10.01 27.8 σree 76.95 94.77 73.72 78.74 8.7 34.46 187.41 100.93 35.19 65.14 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 38 published by scholink inc. table 5. sm-nd isotopic data of the host rocks associated with mn-ores in joda area sample description sm (ppm) nd (ppm) 147sm/144nd 143nd/144nd ± 2 se tdm age (ga) ɛnd 0 1. (laminated phyllite, bichakundi h-quarry) 2.944 12.73 0.1399 0.511805 0.000012 2.79 -16.3 2. (associated bif, khondband mine) 1.913 7.951 0.1455 0.511603 0.000012 3.46 -20.2 note. 1) uncertainty in nd isotopic composition is 2 standard errors; 2) tdm is the depleted mantle model age in ga calculated using the linear model of goldstein et al. (1984); 3) εnd 0 is the epsilon 143nd value calculated present day. figure 1. geological map of noamundi basin showing major manganese deposits in and around joda, associated with bif www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 39 published by scholink inc. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 40 published by scholink inc. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 41 published by scholink inc. figure 2. a) compositionally banded manganiferous phyllite shows brecciated character. b) mn ore body (hosted by phyllite) is exposed in a quarry section. c) rootless intrafolial fold reveals strong deformational events. d) banded hematite jasper (bhj) exhibits its upright folded character. e) concentration of mn ore along the f2 hinge area of a reclined fold. f) thin manganese ore band follows the s2 axial plane. g) quarry section shows folded lithologic units of manganiferous phyllite, mn ore, ferruginous phyllite and hematitic ore. h) folded mn-ore body (hosted by phyllite) is exposed in a quarry section perpendicular to the f2 axis. thickness and mn-ore concentration are maximum at the hinge. i) open type f3 folds in mn ore bodies. patches of kaolinite and ochres of variegated colours are also present. j) normal fault in finely laminated manganiferous phyllite. manganiferous chert formed along the fault surface. k) manganiferous chert (black) is infilling a fault zone in the laminated kaolinized phyllite. l) schematic diagrams showing effects of successive deformational stages of a manganese-ore band in phyllite. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 42 published by scholink inc. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 43 published by scholink inc. figure 3. a) primary compositional banding (s0) shows sub-parallel character with first generation cleavage (s1) whereas s2 plane showing transgressive relationship with them; mn ore gets concentrated in the hinge area of f2 fold. b) syn-kinematic character to d2 is exhibited by micro-folded pyrolusite veins. c) coarse grained bixbyite (bxb) crystals with matching and resorbed boundaries disseminated in cryptomelane-rich groundmass where pyrolusite and cryptomelane both replacing bixbyite crystals d) idioblastic jacobsite grain is disseminated within silicate rich groundmass. e) braunite crystal of earlier generation is being replaced by polianite crystals of later generation. f) colloform banding of cryptomelane and goethite of later generation at the interstitial spaces of fragmented earlier bhq and also enclosing altered braunite crystals of earlier generation. g) pyrolusite and hematite are closely associated at the contact of silicate and iron rich matrix. h) hematite-goethite veins are present within the hematite-goethite matrix. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 44 published by scholink inc. figure 4. correlation of trace elements sc, v, cr, th, ga, nb with al2o3 in mn-ores and host rocks of joda area (blue triangles indicate ores and green stars indicate associated host rocks) www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 45 published by scholink inc. figure 5. geochemical plots of mn-ores and host rocks in joda area (a: diagram from bonatti et al., 1972, b: diagram from choi and hariya, 1992, c: diagram from toth, 1980) (blue triangles indicate ores and green stars indicate associated host rocks) www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 46 published by scholink inc. figure 6. trace element plots for the immobile elements ta, hf, nb against zr in the mn-ores of joda area (blue triangles indicate ores and green stars indicate associated host rocks) www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 47 published by scholink inc. figure 7. chondrite normalized (after mcdonough and sun, 1995) trace element distribution pattern of manganese ores and associated rocks of joda area www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 48 published by scholink inc. figure 8. (a) nasc normalized (after haskin et al. 1968) and (b) average upper continental crust normalized (after taylor and mclennan, 1981) rare earth abundances of manganese ores and associated rocks of joda area www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 49 published by scholink inc. 0.0 0.2 0.4 0.6 0 1 2 3 tho le iiti c bas al t a lk al i b as al t t io 2 ( w t% ) zr/ (p 2 o 5 *104) figure 9. the tio2-zr/(p2o5 *104) discrimination diagram (after winchester and floyd, 1976) manganese ores and associated rocks of joda area (blue triangles indicate ores and green stars indicate associated host rocks) 11. discussion the joda–noamundi sector in the eastern limb of the noamundi synclinorium contains significant manganese mineralization. different tectono-metamorphic events are characterized by distinguished ore mineral assemblages belonging to that particular event. 11.1 deformation & metamorphic events the earliest deformation and metamorphism event (d1/m1) are characterized by the ore mineral assemblage of braunite-bixbyite-jacobsite-hausmannite. the d2/m2 event is characterized by the ore mineral assemblage of pyrolusite-psilomelane-hollandite. d3 stage bears no significant manganese mineralization whereas the post d3 event is characterized by the hydrothermal pyrolusite-psilomelane-chert association occurring along the faults and shear planes. at the final stage of manganese mineralization, supergene activity/lateritization has formed the ore mineral assemblage of polianite-pyrolusite-psilomelane-manganite-goethite precipitated from colloidal solution replacing earlier manganese minerals. the presence of jacobsite-hausmannite assemblage along with triple junction shown by recrystallized bixbyite grains infer that the peak metamorphic condition during d1/m1 attained upper green schist to amphibolite facies, if not higher. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 50 published by scholink inc. 11.2 major & trace element analysis strong positive correlations between sc and al2o3 (figure 4a), v and al2o3 (figure 4b), cr and al2o3 (figure 4c), th and al2o3 (figure 4d), ga and al2o3 (figure 4e), nb and al2o3 (figure 4f) indicate their clastic/detrital origin along with al2o3. the relative enrichment of sc, v, cr in comparison with average zr & th contents indicates the source of clastic materials to be of basic magmatic affinity. on the other hand, co, ni, cu, zn do not show any appreciable variation with sio2 and al2o3 contents of ores and associated rocks signifying that these elements are not directly linked to terrigenous clastic inputs. on ternary diagrams like fe-mn-10 (ni+co+cu) (figure 5a) (after bonatti et al., 1972) and zn-ni-co (figure 5b) (after choi & hariya, 1992) and binary diagram co/zn versus co+ni+cu (figure 5c) (after toth, 1980) and the geochemical data of the ores and host rocks plot in the field of hydrothermal part which depicts a significant role of hydrothermal activities for the enrichment of these highly compatible elements in ore formation process. in the case of chemically incompatible elements, the correlation coefficients for regression lines that pass through the bulk composition and origin can be used to select the most immobile element pair (maclean & kranidiotis, 1987). high field strength elements like nb, ta, zr, and hf, which are widely considered to be immobile, correlate highly with each other in manganese ores of the joda area. sedimentary environment and alteration can shift the immobile element concentrations but have little effect on inter-element ratios, which are controlled largely by the source of detritus in the rocks. within the analytical errors, the chemically incompatible elements nb, ta, hf against zr plot on regression lines through the origin (figure 6 a, b, c). this means that these elements are geochemically coherent and remain immobile during the ore-forming secondary processes. pb is assumed to be derived from cryptomelane. both ba and pb do not vary systematically with al2o3 and sio2 contents inferring their source to be hydrothermal activities at later stages. samples of algoma-type bif of early archean age (3.8ga) from isua, west greenland, have ni values as high as∼58ppm (dymek & klein, 1988). high abundances of ni and cr are also reported from several archean clastic sedimentary rocks, and are generally explained by the presence of an ultramafic source (e.g., mclennan et al., 1983; fedo et al., 1996). in the joda area, average ni and cr contents are 100.5 ppm & 219 ppm respectively. this is more akin to the algoma type character. the relative enrichment of ti, zr, sc in comparison with th possibly infers a recycling product of earlier volcanogenic metabasic rocks. 11.3 ree analysis manganese ores and associated host phyllites comprise a low overall abundance of lrees and a flat pattern of hrees. the lack of marked differentiation between lree and hree hints for a basic affinity as mafic or ultramafic end-members are characterized by small degrees of light-heavy ree fractionation. it is observed that there is a small positive eu anomaly (1.16) and negative ce anomaly (0.88). attenuated eu anomalies account for a more dominating mafic source. manganese ores of the present area show hree enrichment, negative ce anomaly and positive eu anomaly which are similar to modern ferromanganese sediments near mid-oceanic ridges (barrett & jarvis, 1988). in oxic www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 51 published by scholink inc. seawater ce is removed as ceo2 or ce (oh)4 by oxidation reaction. modern seawater has lree depletion and negative ce anomaly (douville et al., 1999). a positive eu anomaly is also a typical characteristic of modern manganese hydrothermal deposits in the ocean (hodkinson et al., 1994). as with the increase of terrigenous components the ce/la ratio increases, the average value of ce/la ratio (1.79) in the manganese ores indicates inclusion of volcaniclastic components, suggesting that the ree pattern and the eu anomalies of the manganese-iron ores in the area are influenced by the mixing of mn rich sea water and volcaniclastics (mishra et al., 2007). the process of lateritization can also promote the loss of ree to some extent (moriyama et al., 2008). the ree patterns shown by the ores and associated rocks represent the end product of a complex series of events that record the properties of the mn rich solutions subsequently precipitated with volcaniclastic sediments. the tio2-zr/(p2o5 *104) discrimination diagram reveals the tholeiitic character of the basic rocks which acted as the major source for derivation of the ore-forming elements. alkali basalts have higher p2o5 than tholeiitic basalts for a given zr content. thus, it can be postulated that the ultimate origin of the ore and associated host rocks is clearly linked to magma of basic composition with prevailing tholeiitic character. 11.4 basinal set-up for ore generation roy (1968) proposed the mn-ores to be of lateritoid type only. banerji (1977) stratigraphically characterized iron-manganese mineralization in the jamda-koira belt as the noamundi group of much younger age (c. 1500-1100 ma) with the following sequence (ascending order): lower shale (tuffaceous shale-phyllite), banded hematite jasper, upper shale (manganiferous shale, tuff and chert), basic intrusion, granitic activity. sarkar and saha (1962, 1977) described manganese ore bodies intimately associated with unmetamorphosed shales (occasionally tuffaceous) and chert of the archean iog. banerji (2002) considered a major part of the materials of the iog rocks was deposited in the miogeosyncline derived from the offshore zone of fracture and volcanism. evidence of earlier crust is also recorded in detrital zircons from supracrustal rocks of these archaean cratons, e.g., ~3.62 ga from singhbhum craton (goswami et al., 1995; misra et al., 1999). according to dunn (1940), dunn and dey (1942) and sarkar and saha (1977) all the iron formations of bihar and orissa belong to one group. iyengar and murthy (1982), banerjee (1982) and acharya (1984) advocated that the bifs belong to different age groups. however, the available two age data reported by mukhopadhyay et al. (2008a) from the dacitic lava from the southern iog of daitari area (3506.8±2.3 ma precision u-pb shrimp zircon age) and basu et al. (2008) from the volcanic rocks of the western iog in the noamundi-koira valley (3.4 ga u-pb zircon age) strongly raises the doubt about the fact that the previously different age-wise classified three iog belts surrounding sbg, belong to one stratigraphic sequence. it is noteworthy that no mn-mineralization is evident from the gorumahisani-badampahar and tomka-daitari iron ore belts. moreover, jamda-koira belt (including joda) and the tomka-daiteri belt comprise only hematitic iron ores, while in the gorumahisani-badampahar belt the iron ore is magnetite-rich. so, the same sedimentary environment in these three belts is difficult to establish at the www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 52 published by scholink inc. present stage. banerji (1974), mukhopadhyay (1976), sarkar (1982), iyenger and murthy (1982) have opined that singhbhum granite is the oldest cratonic block on which the iog rocks were deposited. according to saha et al. (1988), around 3.2 ga there was a development of a tensional regime on either side of singhbhum granite (3.3 ga) following which the bif were deposited in these basins where sbg acts as the basement of iog rocks. on the other hand, baidya (2015) suggests 3500-3200 ma age of the iron ore group when the greenstone belt was formed with concomitant volcanism, sedimentation and ultramafic-mafic magmatism. the oldest granitoid is referred to as the older metamorphic tonalite gneiss (omtg, ~3.4 ga; saha, 1994; goswami et al., 1995; acharyya et al., 2010) that includes enclaves of meta-sediments and meta-volcanics designated as the older metamorphic group (omg). sm-nd isotopic data from the present work indicates the possible maximum age of the rocks (bif) in joda area is 3.46 ga definitely older than the sbg-type a (c. 3.3 ga) which acts as the basement of iog rocks. supergene alteration and hydrothermal activity at later stages may have been attributed for relatively younger age (2.79 ga) of banded cherty phyllite. the limited age data of the present study possibly infers that manganese ores and associated rocks are likely to be recycled from still earlier greenstone belts. 12. conclusion in addition to megascopic and petrographic analyses, the major, trace and rare earth element geochemistry of the manganese ore and associated phyllitic host rocks of the present area confirm the chemistry of the samples as well as the composition of the source material indicative towards a parent magma of basic affinity. the presence of high temperature mineral assemblages (jacobsite-hausmannite) in pyrolusite-cryptomelane rich groundmass indicates an earlier high-grade peak metamorphic condition. manganese, iron and some silica were deposited initially as chemical precipitates in the basin. major oxides al2o3, sio2, k2o, mgo, na2o and tio2 appear to be contributed from volcaniclastics and terrigenous detritus. trace elements appear to be controlled by adsorption on the precipitating mn and fe oxides or hydroxides. the manganese ore bearing bif deposits in a greenstone belt with evidence of volcaniclastic association postulate that bif hosted manganese-iron ores in and around joda are akin to algoma character rather than lake superior type. ree distribution pattern, positive eu anomaly, negative ce anomaly, ce/la ratio all indicating a mixing of basic volcaniclastic material with the chemically precipitated ores. hence, it can be concluded that a basic magma generated in an extensional tectonic set up in archean time acted as the initial source of present-day ore and associated host rocks of joda area. these rocks were later subjected to several stages of deformation and metamorphism with subsequent hydrothermal activities and supergene alteration/lateritization leading to further recycling and enrichment of manganese in younger ore formation. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 1, 2020 53 published by scholink inc. acknowledgements the authors acknowledge sincere cooperation and logistic support of m/s tata steel ltd. during fieldwork particularly mr. tarun chakraborty, mr. manikant, mr. mithun and the present head of the natural resourses manganese division, joda, odisha. sm-nd isotopic studies are done in the australian laboratory services, queensland. epm analytical studies are done in the central petrological laboratory, geological survey of india, kolkata. sincere thanks are also due to ms. riya mondal and mr. rupam ghosh of the dept. of geological sciences, jadavpur university for constructive suggestion and discussion. references acharya, s. 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(1982). the evolving continents (2nd ed., pp. 28-65). john wiley & publication. energy and earth science vol. 3, no. 2, 2020 www.scholink.org/ojs/index.php/ees issn 2578-1359 (print) issn 2578-1367 (online) 80 original paper mantle xenoliths from ibal-oku (oku massif, north-west region, cameroon): imprints of superimposed carbonatitic and silicic metasomatisms sylvin s. t. tedonkenfack 1 , jules tamen 1 , david g. nkouathio 1 *, bertrand t. aziwo 1,2 , kagarabi p. mulimbi 1,3 , yangouo f. kimoun 1 , tabengo m. ziada 1 & sylvie n. f. djukem 1 1 department of earth sciences, faculty of sciences, university of dschang, dschang, cameroon 2 local materials promotion authority (mipromalo), ministry of scientific research and innovation, yaounde, cameroon 3 official university of bukavu, democratic republic of congo * corresponding author: david g. nkouathio, department of earth sciences, faculty of sciences, university of dschang, p.o. box 67, dschang, cameroon received: august 15, 2020 accepted: september 1, 2020 online published: october 29, 2020 doi:10.22158/ees.v3n2p80 url: http://dx.doi.org/10.22158/ees.v3n2p80 abstract mantle xenoliths have been discovered in ibal-oku basalts from oku massif, cameroon volcanic line. these xenoliths analyzed in term of major elements by scanning electron microscope, atomic emission spectrometry, traces and rare earth elements by mass spectrometry are peridotites and pyroxenites. peridotites comprise fe-rich lherzolites, harzburgites and wehrlites. pyroxenites comprise websterites, olivine-websterites, clinopyroxenites and olivine-clinopyroxenites. mineralogically, olivine fo% values and nio content vary from 85 to 91 and 0.26 to 0.43 wt.%, respectively. orthopyroxene is enstatite, mg# values and al content ranging from 0.83 to 0.92 and 0.12 to 0.27 atom per formula unit (apfu), respectively. clinopyroxene is augite and diopside, mg# values and al content ranging from 0.83 to 0.93 and 0.23 to 0.37 apfu, respectively. spinel is aluminous, cr# and mg# values ranging from 0.07 to 0.23 and 0.67 to 0.82, respectively. micas are biotites (fe#: 0.52-0.76). feldspars, which are secondary are sanidine, andesine and labradorite. geochemically, peridotite mg# values vary from 82.7 to 89.9 and pyroxenites from 80.1 to 83.6. the major element variations and some compatible elements are described in terms of partial melting (14-15 vol.% in lherzolites and 17-18 vol.% in harzburgites), whereas the heterogeneities in trace elements are related to carbonatitic/silicic metasomatism. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 81 published by scholink inc. keywords oku massif, cameroon volcanic line, ultramafic xenoliths, partial melting, metasomatism 1. introduction the cameroon volcanic line (cvl) yields the opportunity to studying the sub-continental lithospheric mantle (sclm). this has been the concern of several works based either on volcanic rocks (fitton, 1987; halliday et al., 1988, 1990; marzoli et al., 2000) or on mantle xenoliths (lee et al., 1996; matsukage & oya, 2010; tedonkenfack et al., 2019). in general, the sclm is heterogeneous and it is considered as a result of proportionate mixing of himu, dm and em types (princivalle et al., 2000; njilah et al., 2013; asaah et al., 2014). a few areas along cvl enclose mantle xenoliths dominantly lherzolitic. among these mantle xenoliths bearing areas are the oku massif which have so far been studied: the enep area (nana, 1991, 2001; lee et al., 1996; princivalle et al., 2000; matsukage & oya, 2010), the bafmeng area (chenyi, 2015; chenyi et al., 2017), the nyos sector (lee et al., 1996; nana, 2001; temdjim et al., 2004; matsukage & oya, 2010; teitchou et al., 2011; temdjim, 2012; pinter et al., 2015; liu et al., 2017), the wum area (aziwo, 2015) and the ibal-oku sector (tedonkenfack, 2016; tedonkenfack et al., 2019). in fact, the oku volcanic group (figure 1), located on cvl continental part is built upon pan african (lasserre, 1978; dunlop 1983) plutono-metamorphic basement rocks (dumort et péronne 1966; nana, 1991, 2001; njilah et al., 2004; aziwo, 2015; manjeh, 2016) cross cutted by numerous faults and cracks striking the n30°e, n70°e and n120°e directions. plutonic rocks are dominantly granites and accessorily gabbros and diorites meanwhile metamorphic rocks are dominantly gneisses associated to micaschists and quartzites. oligocene to present volcanic eruption (marzoli et al., 2000; njilah et al., 2004) made up of felsic and mafic lavas yielded through three major volcanic events: 31 to 28 ma, 23 to 21 ma and <1 ma. basically, the first sequence is effusive yielded aphyritic basaltic flows, meanwhile the second one is a mixture of effusive and explosive dynamisms on the one hand and basaltic and trachy-rhyolitic flows associated with rhyolitic tuffs on the other hand. the last sequence, solely explosive, generated tephras. among these three sequences, the second one is characterized by porphyritic basaltic flows which are the host to ultramafic xenoliths. in general, the volcanic products are constituted of basanites, picrobasalts, hawaites, mugearites, benomorites, ignimbrites, trachy-andesites and trachy-basalts (lissom, 1991; nana, 1991, 2001; njilah, 1991; lee et al., 1996; marzoli et al., 1999; asaah et al., 2014; aziwo, 2015; chenyi, 2015; tedonkenfack, 2016; chenyi et al., 2017; wotchoko et al., 2017). ultramafic xenoliths from ibal-oku sector are mainly pyroxenitic (tedonkenfack, 2016; tedonkenfack et al., 2019), unlike other cvl localities (temdjim et al., 2004; wandji et al., 2009; nkouandou & temdjim, 2011; temdjim, 2012; aziwo, 2015; tamen et al., 2015). pyroxenites are worldwide described in veined-peridotites massifs and as peridotite-associated xenoliths in sierra nevada (ghent et al., 1980; ducea, 2002; lee et al., 2006), hannuoba (xu, 2002; liu et al., 2005), hawaii (frey, 1980; sen & leeman, 1991), rio puerco (porreca et al., 2006), kimberley (hills & haggerty, 1989; taylor & neal, 1989; schmickler et al., 2004), www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 82 published by scholink inc. patagonia (laurora et al., 2001; dantas, 2007) etc... along the cvl, the pyroxenites so far studied are websterites, olivine-websterites, ortho-and clinopyroxenites (caldeira et munha, 2002, 2007; wandji et al., 2009; matsukage et oya, 2010; aziwo, 2015; tamen et al., 2015; tedonkenfack, 2016; tedonkenfack et al., 2019). basically, on textural point of view, theses pyroxenites display cumulative derivation (caldeira et munha, 2002, 2007; wandji et al., 2009; matsukage et oya, 2010; aziwo, 2015). petrologically, we intend in this paper to characterize the sclm of the ibal-oku area. figure 1. geological map of the study area note. the inset on the left shows the position of the oku volcanic group along the cameroon volcanic line. the volcanic rocks cut through basement rocks of precambrian age (asaah et al., 2015, modified). 2. method mineral compositions were determined on 10 samples (01 for basaltic host lavas and 09 for ultramafic xenoliths) using sem-eds (scanning electron microscope-energy dispersive spectrometry) method, follow the general standard conditions. analyses were carried out in the laboratory of experimental petrology from institute of geological sciences (poland). for major, trace and rare earth geochemistry, ten samples were selected. the analyses were carried out in the laboratory als minerals of vancouver (canada). major elements were analyzed through the icp-aes method meanwhile trace and rare earth elements were analyzed thanks to icp-ms. detection limits are low: 0.01 wt. % for major elements, 0.01 to 20 ppm for trace elements and 0.01 to 0.5 ppm for rare earth elements. the lost on ignition are also low (less than 0.5 wt. %). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 83 published by scholink inc. 3. result 3.1 petrography 3.1.1 host basalt the mantle xenolith host lavas are porphyritic basalts displaying olivine and pyroxene phenocrysts. a few olivine (ol) and pyroxene, both clinopyroxene (cpx) and orthopyroxene (opx) however constitute with spinel (spl), mantle xenocrysts with oxydated and spongious rims. olivine grains are automorphic to sub-automorphic and vary from 0.05 to 2.5 mm in size. they sometimes enclose oxyde crystals. cpx grains are also automorphic and vary from 0.04 to 2.3 mm in size. their crystals are usually zoned, poikiilitic and enclose small oxyde, plagioclase and apatite grains. plagioclase crystals are automorphic to xenomorphic. the size varies from 0.05 to 0.3 mm. xenomorphic crystals are usually enclose in cpx. oxyde grains are sub-automorphic to xenomorphic. the grain size varies from 0.01 to 0.1 mm and they are sometimes zoned. apatite grains are automorphic, ranging from 0.01 to 0.1 mm in size. 3.1.2 ultramafic xenoliths twenty-six ultramafic xenolith (5-9 cm) were selected for petrography. their modal composition, determined by point counting and projected onto the ol-opx-cpx triangular diagram (figure 2) discriminates them as peridotites and pyroxenites. peridotites are made up of wehrlites (t8), lherzolites (oku11, oku12, oku13, oku20, t9 and t10) and harzburgites (oku17 and oku18). pyroxenites are made up of olivine-websterites (oku6, t3, t4 and t7), websterites (oku38b, t1, t2, t5 and t6), clinopyroxenites (oku1, oku2, oku3, oku5, oku7, oku10 and oku38a) and olivine-clinopyroxenite (oku4). figure 2. nomenclature of the ibal-oku ultramafic rocks (lemaitre, 2002) www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 84 published by scholink inc. 3.1.2.1 peridotites lherzolites display porphyroclastic and secondary protogranular textures, and enclose 50 to 81.72 vol.% of olivine, 7.78 to 23.6 vol.% of clinopyroxene, 8 to 26.51 vol.% of orthopyroxene, 0 to 4.90 vol.% of spinel, 0 to 0.28 vol.% of biotite and 0 to 1.39 vol.% of feldspar. crystals span a wide range of dimension and are in equilibrium, thus showing franc borders. nevertheless, they are spongy-textured when in contact with intraxenolitic melt veinlets. olivine crystals are the largest in size as they range from 0.1 to 6 mm. they are mostly xenomorphic and subsidiarily sub-automorphic. olivine crystals from protogranular rocks display no sign of internal deformation on the contrary of porphyroblastic rock ones which often exhibit kink-bands. crystals often develop polygonal or triple junction (figure 3a). similar to other mineral phases, some crystals enclose fluide inclusions (figure 3b). clinopyroxene crystals also are autoto xenomorphic, ranging from 0.1 to 5 mm. a few of them are poikilitic and enclose small spinel grains. orthopyroxene crystals are autoto xenomorphic, often rounded and interstitial and ranging in dimension between 0.05 and 3 mm. they enclose small rounded spinel grains. spinel crystals (0.05-1 mm) are most often anhedral and exhibit several habits: crystal in contact with melt veinlets are compositionally textured, with brown core and thick-oxidized spongy rims meanwhile the others are either dark. moreover, these spinel crystals are string beans-textured or mechanically dispersed, thus interstitial or included in other mineral phases. biotite crystals (0.1-0.5 mm) are automorphic with good longitudinal cleavages (figure 3c). grains are in interstice between all the other mineral phases. feldspar crystals are the smallest crystals (0.05-0.1 mm). they are automorphic to xenomorphic and are either interstice or included in the other mineral phases (figure 3d). wehrlites are porphyroblastic and made up of 77.74 vol.% of olivine, 16.26 vol.% of clinopyroxene, 3.5 vol.% of orthopyroxene and 2.5 vol.% of spinel. olivine and clinopyroxene have coarse grains than orthopyroxene and spinel. the latter is often included in the silicates phases or form strings along the other mineral borders. olivine crystals (up to 5 mm in size) are often enclose the three other minerals. on the contrary, it is never found as inclusion. its borders are either curvy or rectilinear and franc unless when in contact with glass veinlets or spongious mineral phases (figure 3e). cpx have similar borders and its crystals are subto anhedral and exsolution-free. it displays spongy borders along the contact with glass veinlets and a few crystals are poikilitic. opx exhibit similar habits with cpx, but is at most 1 mm in size, thus found sometimes as interstitial mineral, as well as spinel grains which dimensions are comparable. wehrlite spinel habits follow that of lherzolites and harzburgites from every point of view. however, when they are included in olivine crystal, spinel develop radial cracks in the host (figure 3f). glass veinlets radiate along intracrystalline cracks or percolate along grain boundaries, thus inducing spongy-borders. harzburgites display porphyroclastic and secondary protogranular textures, and enclose 73.68 to 81.72 vol.% of olivine, 13.02 to 22.97 vol.% of orthopyroxene, 2.49 to 2.51 vol.% of clinopyroxene and 0.84 to 2.77 vol.% of spinel. olivine crystals are the largest in size as they range from 0.1 to 5 mm. they are www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 85 published by scholink inc. xenomorphic to sub-automorphic. similar to lherzolite olivine porphyroblasts, porphyroblastic olivine often exhibit kink-bands (figure 3g). orthopyroxene crystals vary from 0.1 to 4 mm in size. a few of them are poikilitic and enclose small clinopyroxene grains. they are sub-automorphic. clinopyroxene crystals vary from 0.01 to 1 mm in size. they are xenomorphic to sub-automorphic. a few of them are also poikilitic and enclose small orthopyroxene and spinel grains. spinel crystals vary from 0.1 to 3 mm in size. they are xenomorphic to sub-automorphic. in contact with glass, they usually exhibit spongious borders (figure 3h). 3.1.2.2 pyroxenites olivine-websterites and websterites exhibit cumulative texture. they differ mainly in their mineral modal proportions and in the presence of calcite and apatite in websterites. in this light, ol-websterites display compositions in the frame of 40.13 to 65.65 vol.% of cpx, 23.27 to 46.37 vol.% of opx, 9.5 to 14.63 vol.% of ol and 0 to 1.11 vol.% of feldspars, meanwhile websterites enclose 71.95 to 86.84 vol.% of cpx, 12.16 to 24 vol.% of opx, 0.1 to 4 vol.% of ol, and <1 vol.% of apatite and calcite (~0.4 vol.% each). porphyroblasts of the three mineral phases are sub-automorphic and comparable in size (2 to 5 mm across). some cpx porphyroblasts exsolve opx as lamellae along their cleavages and/or enclose opx microcrysts forming string grains. besides, a few cpx crystals are poikilitic and enclose small rounded spinel grains and fine orthopyroxenes exsolution lamellae (figure 3i). opx porphyroblasts on their own show cpx lamellae and needle-like exsolutions often accompanied by randomly distributed microcrysts of the same nature. their neoblasts are subto circular and aligned along opx-cpx porphyroblast boundaries. olivine crystals are sometimes iddingsitized. apatite (0.39 to 0.52 mm) and calcite (0.52 mm) are the smaller crystals and they are most often anhedral and enclose in the websterite clinopyroxene crystals (figure 3j). host basaltic melt veins sometimes infiltrate the xenoliths. feldspar crystals (0.01-0.1 mm) are automorphic to xenomorphic and are either interstice or included in the other mineral phases. clinopyroxenites and olivine-clinopyroxenites differ mainly in their mineral modal proportions and the absence of orthopyroxene in olivine-clinopyroxenites. clinopyroxenites enclose 89.47 to 99.44 vol.% of clinopyroxene, 0.56 to 7.55 vol.% of orthopyroxene, 1.21 to 2.49 vol.% of olivine and 1.11 vol.% of feldspar. olivine-clinopyroxenites enclose 77.25 vol.% of clinopyroxene, 21.07 vol.% of olivine and 1.68 vol.% of feldspar. in both of them, cpx are poikilitic and enclose opx grains. few clinopyroxene crystals exhibit spongious rims in with small plagioclase grains are present (figure 3k). feldspar, olivine and oxide crystals are interstitial between pyroxene grains or present in the mineral pocket (figure 3l). they are porphyroclastic. however, few rocks exhibit cumulative texture. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 86 published by scholink inc. figure 3. photomicrographs of ultramafic xenoliths. (a) polygonal triple junction between ol grains. (b) fluid inclusions in ol. (c) biotite grain. (d) plagioclase and sanidine grains. (e) ol-opx interaction. (f) inclusion of spl crystal. (g) kink-bands in ol crystals. (h) spl with spongeous rims in contact with glass. (i) opx exsolution. (j) inclusion of cal crystals. (k) cpx with spongeous rims. (l) opx pocket 3.2 mineral chemistry 3.2.1 host lavas olivine phenocrysts (fo75.48-84.04) are always more forsteritic than microcrysts (fo75.48-76.70). cao and nio content vary from 1455 to 2182 wt.% and 0.1 to 0.3 wt.%. respectively (table 1). olivine xenocrysts are relatively more forsteritic (fo85.66) than those of the host lavas. cao and nio content are 1455 wt.% and 0.4 wt.%. respectively. clinopyroxenes are calcic and made up of diopside (wo45.07-48.57en39.16-43.43fs10.82-13.42; mg#: 0.75-0.80) and augite (wo43.30-44.42en39.77-44.92fs10.66-16.06; mg#: 0.71-0.81). al, cr, ca, na and ti content vary from 0.15 to 0.39 apfu, 0.01 to 0.02 apfu, 0.80 to 0.87 apfu, 0.04 to 0.07 apfu and 0.05 to 0.10 apfu respectively (table 3). feldspars are plagioclases. they are made up of labradorite (an50.13-62.20ab36.02-47.56or1.16-2.32). fe 2+ content varies from 0.03 to 0.04 apfu (table 5). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 87 published by scholink inc. 3.2.2 ultramafic xenoliths 3.2.2.1 peridotites olivine fo varies from 86 to 90 (table 1; figure 4a). these values are positively correlated with coexisting pyroxene mg#. nio and ca content are 0.03 wt.% and 727-1455 wt.% respectively. orthopyroxenes are enstatite (en83.15-87.77fs12.23-16.85). mg# values ranging from 0.83 to 0.92 (table 2; figure 4c). al content varies from 0.12 to 0.27 apfu and are negatively correlated with mg# values. cr content varies from 0.004 to 0.022 apfu. on contrary to al content, cr content are positively correlated with mg# values. clinopyroxenes are calcic and made up of augite (wo35.52-43.35en49.39-60.25fs5.49-10.59). mg# values vary from 0.84 to 0.93 (table 3; figure 4d). al content varies from 0.23 to 0.37 apfu and are negatively correlated with mg# values. cr content varies from 0.007 to 0.038 apfu and are positively correlated with mg# values. ca content varies from 0.63 to 0.85 apfu. na content varies from 0.06 to 0.15 apfu and are positively correlated with mg# values and al content. ti content varies from 0.007 to 0.030 apfu. spinels are aluminous (al2o3: 46.10-60.70 wt.%). cr# (cr#=cr/cr+al) and mg# (mg#=mg/mg+fe) vary from 0.10 to 0.23 and 0.67 to 0.71, respectively (table 4; figure 4b). fe 2+ content varies from 0.15 to 0.27 apfu. ti content varies from 0.001 to 0.016 apfu. micas are biotite with fe# (fe/fe+mg) ranging from 0.52 to 0.76 (table 4; figure 4e-f). si, ti and al content vary from 6.27 to 7.99 apfu, 0.04 to 0.16 apfu and 1.01 to 1.81 apfu respectively. feldspars are sanidine (or35.64-45.04ab51.13-56.98an3.32-7.60) and andesine-labradorite (an30.41-55.28ab42.99-64.49or1.73-5.09). fe 2+ content varies from 0.02 to 0.04 apfu (table 5). 3.2.2.2 pyroxenites olivine fo vary from 85 to 87 (table 1; figure 4a). nio and ca content are 0.03 wt.% and 727-2182 wt.% respectively. orthopyroxenes are enstatite (en83.15-87.77fs12.23-16.85). mg# values vary from 0.85 to 0.88 (table 2; figure 4c). al, cr, ca, na and ti content vary from 0.15 to 0.39 apfu, 0.01 to 0.02 apfu, 0.80 to 0.87 apfu, 0.04 to 0.07 apfu and 0.05 to 0.10 apfu, respectively. clinopyroxenes are calcic and made up of augite (wo35.52-43.35en49.39-60.25fs5.49-10.59; mg#: 0.83-0,87; table 3; figure 4d). al content varies from 0.23 to 0.37 apfu. on contrary, cr content varies from 0.007 to 0.038 apfu. ca content varies from 0.63 to 0.72 apfu. na content varies from 0.06 to 0.09 apfu. ti content varies from 0.007 to 0.030 apfu. feldspars are andesine-labradorite (an30.41-55.8ab42.99-64.49or1.73-5.09). fe 2+ content varies from 0.02 to 0.04 apfu (table 5). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 88 published by scholink inc. figure 4. variation diagram of mineral analyses. (a) relationship between nio and fo[%] content in olivine. (b) relationship between cr# and mg# in spinel. (c) relationship between al (apfu) and mg# in orthopyroxene. (d) relationship between al (apfu) and mg# in clinopyroxene. (e) and (f) relationships between fe# and si (apfu) and al (apfu) in biotite www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 89 published by scholink inc. table 1. selected olivine analyses types lher lher lher harz harz clin ol-clin ol-clin ol-clin basalt basalt oku11 oku11 oku12 oku17 oku18 oku38a oku4 oku4 oku4 oku39 oku39 1 2 3 4 5 6 7 8 9 10 11 sio2 40.2 39.9 40 40.1 40.6 39.4 39.3 39.5 39.4 39.4 39 feo 12.6 12.6 12.5 9.5 9.1 14.4 14.2 13.7 13.8 15.7 15.8 nio 0.3 0.3 0.3 0.3 0.3 0.2 0.3 0.3 0.3 0.3 0.2 mgo 46.7 47.1 47.1 49.7 50 45.9 46.1 46.3 46.3 44 44.6 cao 0.2 0.1 0.1 0.1 0.1 0.2 0.1 0.2 0.3 0.2 0.3 total 100 100 100 99.7 100.1 100.1 100 100 100.1 99.6 99.9 si 4+ 0.9987 0.9919 0.9937 0.9855 0.9921 0.9872 0.9853 0.9879 0.9855 0.996 0.9862 fe 2+ 0.2618 0.262 0.2597 0.1953 0.186 0.3017 0.2977 0.2865 0.2887 0.3319 0.3341 mn 2+ 0 0 0 0.0042 0 ni 2+ 0.006 0.006 0.006 0.0059 0.0059 0.004 0.0061 0.006 0.006 0.0061 0.0041 mg 2+ 1.7295 1.7455 1.7443 1.8209 1.8214 1.7145 1.723 1.7262 1.7263 1.6581 1.6813 ca 2+ 0.0053 0.0027 0.0027 0.0026 0.0026 0.0054 0.0027 0.0054 0.008 0.0054 0.0081 total 3.0013 3.0081 3.0063 3.0145 3.0079 3.0128 3.0147 3.0121 3.0145 2.9976 3.0138 fo% 86.8 86.9 87.0 90.1 90.7 85.0 85.2 85.7 85.6 83.0 83.4 ca (ppm) 1455 727 727 727 727 1455 727 1455 2182 1455 2182 table 2. selected orthopyroxene analyses types lher lher harz harz webs ol-webs clin clin oku11 oku12 oku17 oku18 oku38b oku6 oku38a oku7 1 2 3 4 5 6 7 8 sio2 52.4 52.8 53.6 54.1 52.7 53 53.4 53.2 tio2 0.4 0.4 0.2 0.2 0.4 0.3 0.3 0.4 al2o3 6.3 6.2 5.4 5 6.1 5.9 5.4 4.8 cr2o3 0.5 0.4 0.7 0.8 0.3 0.3 feo 7.8 8.2 6.2 5.7 9.4 8.4 8.9 9.1 mno 0.2 mgo 31.1 30.7 32.6 32.9 29.9 30.4 30.4 30.5 cao 1.5 1.4 1.3 1.4 1.5 1.5 1.6 1.6 total 100 100.1 100 100.1 100 100 100 99.9 si +4 1.7442 1.7575 1.7842 1.8008 1.7542 1.7642 1.871 1.7709 ti +4 0.01 0.01 0.005 0.005 0.01 0.0075 0.008 0.01 al +3 0.1854 0.1824 0.1589 0.1471 0.1795 0.1736 0.223 0.1412 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 90 published by scholink inc. cr +3 0.0099 0.0079 0.0138 0.0158 0.0059 0.0059 fe +2 0.1086 0.1141 0.0863 0.0793 0.1308 0.1169 0.261 0.1267 mn +2 0.0028 mg +2 0.7716 0.7617 0.8088 0.8163 0.7418 0.7542 1.588 0.7567 ca +2 0.0267 0.025 0.0232 0.025 0.0267 0.0267 0.06 0.0285 total 2.8564 2.8587 2.8802 2.8893 2.8431 2.852 4.0099 2.8399 mg# 0.8767 0.8697 0.9036 0.9114 0.8501 0.8658 0.8589 0.8566 table 3. selected clinopyroxene analyses types lher lher harz harz ol-webs clin clin ol-clin basalt basalt oku11 oku12 oku17 oku18 oku6 oku7 oku38a oku4 oku39 oku 39 1 2 3 4 5 6 7 8 9 10 sio2 50.2 50.2 51.6 51.8 51 51.6 51.3 50.8 48.1 48.5 tio2 0.9 0.9 0.4 0.4 0.8 0.7 0.5 0.9 1.8 1.8 al2o3 7.7 7.8 6.5 6.3 7.1 5.9 6.7 6.4 7 6.5 cr2o3 0.7 0.6 1.1 1.2 0.4 0.3 0.3 0.3 0.8 feo 5.4 4.7 3.6 3.3 4.9 6 5.9 4.7 7.8 6.3 mno 0.3 0.3 mgo 16.8 16.8 17.5 17.8 17.1 18 17.8 17.6 12.9 14.9 cao 17.3 17.8 18.2 18.1 17.6 16.4 16.3 19.1 21.8 20.5 na2o 1.1 1 1.2 1.1 1 1 1.1 0.6 0.6 total 100.1 100.1 100.1 100 99.9 99.9 99.9 100.1 100 99.9 si 4+ 1.8215 1.8197 1.861 1.8665 1.8473 1.8715 1.8592 1.8416 1.7928 1.7944 ti 4+ 0.0246 0.0245 0.0108 0.0108 0.0218 0.0191 0.0136 0.0245 0.0505 0.0501 al 3+ 0.3293 0.3332 0.2763 0.2675 0.3031 0.2522 0.2862 0.2734 0.3075 0.2834 cr 3+ 0.0201 0.0172 0.0314 0.0342 0.0115 0.0086 0.0086 0.0086 0 0.0234 fe 2+ 0.1639 0.1425 0.1086 0.0994 0.1484 0.182 0.1788 0.1425 0.2431 0.1949 mn 2+ 0.0092 0.0092 mg 2+ 0.9087 0.9078 0.9409 0.9561 0.9234 0.9732 0.9617 0.9511 0.7168 0.8218 ca 2+ 0.6726 0.6913 0.7033 0.6988 0.6831 0.6373 0.633 0.7419 0.8706 0.8126 na + 0.0774 0.0703 0.0839 0.0768 0.0702 0.0703 0.0773 0 0.0434 0.043 total 4.018 4.0157 4.0162 4.0102 4.0087 4.0142 4.0184 3.9929 4.0247 4.0237 mg# 0.8472 0.8643 0.8965 0.9058 0.8615 0.8425 0.8432 0.8697 0.7467 0.8083 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 91 published by scholink inc. table 4. selected spinel and micas analyses spinel micas types lher lher harz harz harz lher lher lher lher oku11 oku12 oku17 oku18 oku18 oku12 oku12 oku12 oku12 1 2 3 4 5 6 7 8 9 sio2 58.7 54.5 54.4 41.7 tio2 0.6 0.6 0.3 0.4 0.3 0.4 0.4 1.4 al2o3 53.1 54.5 50.2 46.6 46.5 6.9 7.7 7.4 10.2 cr2o3 11.1 9.4 16.3 20.4 20.6 0.8 feo 16.1 15.7 12.5 12.3 12.2 19.6 23.4 24.1 35.3 nio 0.3 0.5 mgo 19 19.7 20.4 20.3 20.4 8.9 7.9 7.1 6.2 cao 0.7 0.6 0.6 0.7 k2o 5.3 5.4 5.4 3.8 total 99.9 99.9 100 100 100 100.1 99.9 99.9 100.1 si 4+ 7.904 7.558 7.589 6.265 ti +4 0.012 0.012 0.006 0.008 0.006 0.042 0.042 0.158 al +3 1.653 1.681 1.565 1.472 1.469 1.095 1.258 1.217 1.806 cr +3 0.232 0.195 0.341 0.432 0.437 0.095 fe +2 0.356 0.344 0.277 0.276 0.273 2.207 2.714 2.811 4.435 ni +2 0.006 0.056 mg +2 0.748 0.769 0.805 0.811 0.815 1.786 1.633 1.476 1.389 ca 2+ 0.101 0.089 0.09 0.113 k + 0.91 0.955 0.961 0.728 total 3 3 3 3 3 14.004 14.249 14.242 14.99 fe +3 calc 0.092 0.101 0.082 0.079 0.083 fe +2 calc 0.264 0.243 0.195 0.197 0.191 mg/(mg+fe 2+ ) 0.739 0.76 0.805 0.805 0.81 0.447 0.376 0.344 0.238 mg/(mg+fetot) 0.678 0.691 0.744 0.746 0.749 cr# 0.123 0.104 0.179 0.227 0.229 fe# 0.553 0.624 0.656 0.762 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 92 published by scholink inc. table 5. selected feldspar analyses types lher ol-webs clin ol-clin basalt oku12 oku6 oku38a oku4 oku39 1 2 3 4 5 6 7 8 9 10 11 12 sio2 57.5 63.8 64.5 57.7 57.3 59 57.6 52.9 55.8 51.7 54.3 51.3 tio2 0.5 0.5 0.6 0.3 0.3 al2o3 26.9 20.7 19.9 25.7 26.7 25.5 26.7 29.6 27.8 30.6 28.6 29.4 feo 0.8 0.6 0.5 0.8 0.7 0.4 0.4 0.9 0.7 0.9 1 cao 7.6 1.6 0.8 7.4 7.9 6.5 7.8 11.4 8.8 12.5 10.3 16.7 na2o 6.8 6.6 5.9 7.1 7 7.4 6.8 4.9 6.4 4 5.4 0.6 k2o 0.5 6.3 7.9 0.7 0.4 0.8 0.7 0.3 0.5 0.3 0.4 0.2 total 100.1 100.1 100 100 100.3 99.9 100 100 100 100 100 98.2 si +4 2.58 2.874 2.916 2.598 2.57 2.644 2.587 2.404 2.518 2.354 2.461 2.37 ti +4 0.017 0.017 0.02 0.01 0.01 al +3 1.423 1.099 1.06 1.364 1.412 1.347 1.413 1.585 1.478 1.642 1.528 1.601 fe +2 0.03 0.023 0.019 0.03 0.026 0.015 0.015 0.034 0.026 0.034 0.038 ca +2 0.365 0.077 0.039 0.357 0.38 0.312 0.375 0.555 0.425 0.61 0.5 0.827 na + 0.592 0.576 0.517 0.62 0.609 0.643 0.592 0.432 0.56 0.353 0.474 0.054 k + 0.029 0.362 0.456 0.04 0.023 0.046 0.04 0.017 0.029 0.017 0.023 0.012 total 5.019 5.029 5.023 5.03 5.03 5.017 5.023 5.028 5.037 5.01 5.024 4.863 an (%) 37 8 4 35 38 31 37 55 42 62 50 93 ab (%) 60 56 51 61 60 64 59 43 55 36 48 6 or (%) 3 36 45 4 2 5 4 2 3 2 2 1 3.3 geochemistry 3.3.1 major elements major elements ranges as shown by table 6 portray the broad ultramafic rocks suite described here. mgo varies thus widely between 15.85 and 40.5 wt. %. the variation is however reasonable in each of the petrographic type: 29 to 40.5 wt. % in peridotites, 15.85 to 26.6 wt. % in pyroxenites. although peridotites display the highest deviation, it should be noted that one sample show an uncommon (29 wt. %) content for peridotites. the mg# varies between 82.7 and 89.9 for peridotites and 80.1 to 83.6 for pyroxenites. these peridotite mg# are rather low when compared to values so far recorded along the cvl. they however reveal their iron-rich nature, similarly to fe-rich lherzolites and wehrlites from tok, se siberia (ionov et al., 2005) or from horníbory, bohemian massif (ackerman et al., 2009). mgo correlates variably with the other major elements. figure 5 shows that, refractory lithophiles elements (rle) al2o3, cao and na2o and to a lesser extend sio2 display a negative correlation with www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 93 published by scholink inc. mgo. contrarily, feot and k2o exhibit a rough positive trend. al2o3 and cao alike mgo display a wide range of contents (2.25-7.55 wt. % and 1.57-16.5 wt. % respectively). peridotites show the smallest contents. two significant observations arise from the behavior of these two rle: (i) cao portrays a horizontal rather than the al2o3 negative trend, and (ii) al2o3 contents are typical of fertile lherzolites meanwhile cao contents are close (2.28 wt. %) or even similar (1.57-1.89 wt. %) to harzburgites compositions (palme and o’neill, 2014). p2o5and k2o contents range in the order of almost two magnitude (0.03-0.13 wt. % and 0.03-0.16 wt. % respectively), characterized by the greatest scatter in the mgo variation diagram. notwithstanding the broad suite contents, peridotites display pm comparable contents, except for feot, p2o5 and k2o which are slightly enriched. figure 5. variation diagram of selected oxides vs mgo. primordial mantle (pm) composition after mcdonough and sun (1995) www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 94 published by scholink inc. 3.3.2 trace and rare earth elements table 6 shows that over the rocks suite, trace elements display extensive concentrations and often, pyroxenites are richer: cr (740-2340 ppm in peridotites vs 1380-2640 ppm in pyroxenites) and v (60-110 ppm in peridotites vs 134-240 ppm in pyroxenites). rb however has similar values in both petrographic rock types. figure 6 which portrays variation of mgo vs a selected set of trace elements reveals that v is the sole element perfectly correlated to mgo. cr, zr, sr and ba despite their extensive concentrations are either vertically aligned (websterites) or scattered (olivine-websterites), likely as a result of the close range mainly of pyroxenites mgo contents. figure 6. variation diagram of selected traces elements vs mgo chondrite-normalized spidergram yields mirroring spectra for the two petrographic facies (figure 7a), though sections of overlapping or detachment may exist (figure 7b). rb, k and p depict severe negative anomalies of a factor of 45, 50 and 300 respectively, meanwhile ba exhibits a rough positive anomaly of a factor of 4.5. chondrite-normalized diagram (figure 7c and 7d) show an overall lree enrichment relative to hree. the (la/lu)n ratios vary between 4.2 and 10 for peridotites and between 2.9 and 9.52 for pyroxenites. it is obvious to note that the pyroxenites lree enrichment over hree is more spread. on the other hand, all the oku rocks are ree enriched with respect to chondrite but its order of magnitude is far beyond two units (35). the pyroxenites spectra have a more regular pattern than that of peridotites and moreover, they all have higher contents. some of the peridotites display rough ce and tm positive anomalies of a factor of 1.7 and 2 respectively. www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 95 published by scholink inc. figure 7. chondrite-normalized diagrams for the oku ultramafic rocks. (a) and (b) curves and redrawn shaded fields for the same rocks with the traces elements. (c) and (d) curves and redrawn shaded fields for the same rocks with the rare earth elements. normalization values after sun and mcdonough (1989) table 6. bulkrock major, trace and ree compositions of the oku mantle xenoliths peridotites pyroxenites wehrlite lherzolites olivine-websterites websterites samples t8 t9 t10 t3 t4 t7 t1 t2 t5 t6 sio2 42.1 48.4 40 46.3 49.9 43.9 48.7 50.1 49.8 47.6 tio2 0.25 0.36 0.39 0.56 0.62 0.89 0.69 0.78 0.79 1.09 al2o3 2.25 4.8 3.74 4.17 6.05 4.33 6.15 6.37 6.75 7.55 cr2o3 0.3 0.1 0.32 0.19 0.36 0.19 0.3 0.35 0.24 0.25 a feot 10.65 14.15 15.05 12.9 9.51 12.25 9.1 8.09 8.49 9.21 mno 0.14 0.21 0.21 0.17 0.16 0.16 0.16 0.14 0.15 0.16 mgo 40.5 29 35.5 26.6 20.7 26.2 17.5 17.65 16.65 15.85 cao 1.57 1.89 2.28 7.91 12.3 9.76 13.85 15.3 16.5 15.05 na2o 0.16 0.18 0.16 0.39 0.67 0.47 0.84 0.79 0.82 0.82 k2o 0.09 0.07 0.06 0.08 0.03 0.16 0.06 0.05 0.06 0.1 p2o5 0.03 0.04 0.07 0.05 0.04 0.13 0.03 0.03 0.05 0.11 b loi 0.7 0.44 1.63 1.05 0.98 1.25 0.72 0.9 1.07 1.47 total 98.74 99.64 99.41 100.37 101.32 99.69 98.1 100.56 101.37 99.26 mg# 89.9 82.7 84.6 82.8 83.6 83.3 81.8 83.6 82.1 80.1 nb 2.4 1.7 2.4 4 2.1 9.7 2.1 2.3 3.2 6.9 zr 12 13 17 25 20 43 28 31 29 48 sr 30.5 15 11.3 60.4 32 122 52.5 66.6 60.8 101 ga 3.4 7 6.1 6.6 8.3 7.1 8.6 8.6 8.6 10.8 cr 2180 740 2340 1440 2640 1380 2200 2580 1730 1870 v 60 110 100 139 212 145 240 225 254 260 ba 29.2 27.1 34.6 44.6 15.6 95.7 38.1 21.7 107 66.4 rb 1.9 2.9 3 2.1 1.2 2.3 1.9 1.9 2 1.4 www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 96 published by scholink inc. cs 0.02 0.05 0.06 0.1 0.02 0.05 0.07 0.06 0.08 0.11 y 2 1.8 3.8 6.3 7 8 9.3 8.7 9 12.8 hf 0.3 0.4 0.6 0.8 0.8 1.2 0.9 1.1 1.1 1.7 sn 1 1 1 1 1 1 1 1 1 3 ta 0.1 0.1 0.1 0.2 0.1 0.5 0.1 0.1 0.2 0.4 th 0.17 0.15 0.32 0.29 0.17 0.63 0.2 0.19 0.25 0.5 u 0.05 0.06 0.1 0.11 0.07 0.18 0.1 0.07 0.1 0.15 la 2.8 1.2 2.8 4.3 1.9 8 5.3 3.3 3.9 8.3 ce 4.5 3.4 6.2 7.6 5.3 15.9 6.5 7.9 9.3 16.2 pr 0.61 0.32 0.68 1.33 0.79 2.25 1.54 1.24 1.44 2.41 nd 2.6 1.2 2.9 6.5 4.4 10.3 7.4 6.8 7.1 11.8 sm 0.53 0.37 0.76 1.66 1.39 2.16 2.33 1.95 2.33 3.2 eu 0.17 0.1 0.21 0.55 0.53 0.81 0.62 0.66 0.68 1.02 gd 0.54 0.33 0.79 1.72 1.58 2.18 2.3 2.24 2.25 3.3 tb 0.07 0.06 0.12 0.26 0.27 0.31 0.35 0.37 0.34 0.47 dy 0.43 0.34 0.69 1.41 1.56 1.75 2.06 2 1.98 2.64 ho 0.08 0.07 0.16 0.26 0.3 0.33 0.37 0.37 0.39 0.51 er 0.18 0.18 0.38 0.64 0.73 0.75 0.99 0.87 0.97 1.22 tm 0.04 0.05 0.06 0.09 0.11 0.1 0.12 0.14 0.11 0.17 yb 0.24 0.18 0.35 0.49 0.58 0.59 0.73 0.68 0.63 0.89 lu 0.03 0.03 0.05 0.07 0.07 0.09 0.1 0.1 0.11 0.12 note. a feot: fe total; b loi: loss on ignition. 4. discussions the ibal-oku ultramafic rocks described here are included in dismantled basaltic flows. a few of these xenoliths are veined by the host basalt meanwhile the outer contact is sometimes reactive, leading to the development of augitic clinopyroxene. contrarily to the other ultramafic xenolith reservoirs along the cvl, pyroxenites are more represented than peridotites and although their textures are similar to the main ones recorded elsewhere in cameroon, their petrology and iron-rich signature are specific features that request thorough considerations. 4.1 petrographic evolution 4.1.1 origin of peridotites ultramafic xenolith sizes are very important. in fact, small size are problematic as far as their magmatic or mantellic origin is concerned. magmatic xenoliths have either to do with a precocious crystallization from the host lava or with the phenomenon at the origin of the host magma itself meanwhile mantellic origin is fragment detached either from the source region or from the wall rocks along the magma’s route to the surface. because the latter are accidentally sampled, not all depth intervals are necessarily represented in a xenolith population; nevertheless, their pressures and temperatures estimates provide some spatial context amongst samples within a xenolith population, which may perhaps be divisible according to their textures and/or compositions (pearson et al., 2014). one of the discriminative features of the two origins is their texture, cumulative in the first case, metamorphic in the broad sense since they result from the combination of thermo-barometric and differential stress conditions for the www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 97 published by scholink inc. second. magmatic ultramafic xenoliths have been described along cvl (caldeira & munha, 2002; ngounouno et al., 2006; wandji et al., 2009; matsukage & oya, 2010) and they all fit in this distinctive cumulative signature. the oku samples however display metamorphic textures and low whole rocks and silicate mg#. in the latter view, ionov et al. (2005) define two types of lherzolite series: (i) a lherzolite-wehrlite series (l-w) characterized by low mg# [mg/(mg+fe) at 0.84-0.89 in olivine, high modal olivine (66-84 vol.%) and cpx (7-22 vol.%) substituting for opx (0-12 vol.%) and for spinel and (ii) a lherzolite-harzburgite (l-h) series in which mg# are high (>0.89), with high opx and representing melting residues partially metasomatized. the ibal-oku peridotites mainly plot in osma (olivine spinel mantle area) and lw fields (figure 8-9), confirming their mantellic origin. furthermore, the two samples plotting in the lw field exhibit cr content of 2180 and 2340 ppm, far above critical value characteristic of mantle peridotites. figure 8. relationship between fo[%] content in olivine and cr-number in spinel. osma (olivine spinel mantle area) field from arai (1994) figure 9. co-variation plots of modal abundances of cpx (a) and opx (b) vs ol of the oku peridotites. lherzolite–wehrlite (l-w) series and lherzolite–harzburgite (l-h) series are after ionov et al. (2005). arrows outline inferred trends for transformation of refractory l-h series rocks into l-w series rocks (ionov et al., 2005) www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 98 published by scholink inc. 4.1.2 origin of pyroxenites pyroxenite origin and formation processes are challenging questions highly discuted. in this way, dantas (2007) summarized the literature major formation processes into four modes: (i) oceanic crust fragments recycling (dick & sinton, 1979; kornprobst et al., 1990), (ii) cumulates from early magmatic crystallization (frey, 1980; schiano et al., 2000; puziewicz et al., 2011), (iii) fluid/melt and upper mantle peridotite interaction (menzies, 1983; navon & stolper, 1987; smith & riter, 1997; ackerman et al., 2009), and (iv) high pressure segregation of mafic silicate melts yielding a fluid that later on crystallizes pyroxenites (debari et coleman, 1989; downes, 2005). along the cvl, several pyroxenites occurrences, mainly cumulative have been described (caldeira & munha, 2002; wandji et al., 2009; matsukage & oya, 2010; aziwo, 2015). the ibal-oku pyroxenites however display modal cpx/opx ratios in the range of 0.9 to 7.2, i.e., greater than 1, characteristic of mantle reactive pyroxenites (murad & shoji, 2007). alike the ksieginki (poland) websterite (puziewicz et al., 2011) and the tok lw series, the oku pyroxenites plot at the right of lw-lh line (figure 9), close to the curve modelling the melt-host reaction parameters of 0.99 liq0 + 0.01 opx fi 0.98 liqr+ 0.01782 cpx + 0.00198 ol (eq. 1) after ionov et al. (2005) and can indeed be considered as mantle metasomatic products from early magmatic crystallization, or cumulates. however, petrographic observations show that the majority of pyroxenite display cumulative texture. this characteristic means that they could also be cumulates from early magmatic crystallization. figure 10. a plot of whole-rock mg# vs modal cpx/opx (wt %) in oku peridotites compared with results of numerical modelling of mg# variations produced by interaction of a refractory peridotite (mg#=0.91; cpx/opx=0.32) with percolating basaltic liquids involving cpx-forming reactions at decreasing melt mass www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 99 published by scholink inc. the modelling was done using the ―plate model‖ of vernières et al. (1997) initially designed for trace-element applications and modified here for mg–fe modelling. olivine/melt and inter-mineral kd values for mg and fe were fixed for t=1,200 c and p=1.5 gpa from experimental calibrations (brey & köhler, 1990; ulmer, 1989). furthermore, the olivine/melt kd are adjusted as a function of melt composition. the initial peridotite composition (protolith) was obtained by averaging compositions of lh series rocks [with mg# >0.90 to avoid samples possibly affected by small degrees of melt–rock reaction (ionov et al., 2005)]. numerical experiments were performed with two extreme compositions for infiltrated melt: (1) a primitive, high-mg# (0.76) liquid in equilibrium with the protolith and (2) an evolved, low mg# (0.63) liquid similar to the host basalt. all modelling results obtained with the primitive melt composition plot in the shaded area. modelling results for the evolved melt compositions are shown for r values (mass ratio of crystallised minerals to infiltrated melt) ranging from 0.02 to 0.3. based on eq. 1 in text and constant ƒ (residual melt fraction)=0.99, the melt-host reaction parameters range from [0.99 liq0+0.01 opx fi 0.98 liqr+0.01782 cpx+0.00198 ol] for r=0.02 to [0.769 liq0+0.231 opx fi 0.761 liqr+0.215 cpx+0.023 ol] for r=0.3. after ionov et al. (2005). 4.2 textural evolution the ibal-oku wehrlites are protogranular, with as lherzolites few olivine crystals displaying straight boundaries that sometimes form triple junctions. lherzolites and harzburgites are either secondary protogranular or porphyroclastic. kink-bands are often observed on some olivine crystals. the typology of mantle rocks textures (mercier et nicolas, 1975; coisy et nicolas, 1978) reveal that xenoliths displaying protogranular textures derive from tectonically inactive mantle areas meanwhile porphyroclastic textures are typical of mantle active zones. as a consequence of the high deformation, a rock can experience a complete process of textural evolution leading to a secondary protogranular texture, characterized by mechanically dispersed spinel which may be included in the rock silicate mineral or form string-grains and/or atolls. such a secondary protogranular texture thus portrays active mantle areas. the oku sclm is likely active, a phenomenon which in the exception of the kumba sclm (teitchou et al., 2007) is almost general along the cvl. deformation textures are known to indicate the presence of shear zones in the mantle, likely resulting from (i) the replay of large horizontal shear zones during oceanic opening, (ii) asthenospheric diapirism within the lithosphere (coisy et nicolas, 1978; witt et seck, 1987) or (iii) the mechanic response to lithosphere/asthenosphere fluxes coupling (kennedy et al., 2002; tikoff et al., 2004). along the cvl where the crust in thin (36 km after tokam et al., 2010) however, the basal lithospheric erosion by the asthenosphere seems to explain the origin of the mantle shearing (elsheikh et al., 2014). in addition to protogranular and porphyroclastic textures in oku, poikilitic spongy microtextures are sometimes superimposed. such microtextures originate either from local melting through metasomatism prior to the sampling by the host magma or from melt/xenolith interaction during host magma ascent (ionov et al., 1994; qi et al., 1995; carpenter et al., 2002). poikilitic and spongy cpx are often associated to festooned border spinel and vugs, but unlike the dibi (dautria & girod, 1986), kapsiki (tamen et al., 2015), wum (aziwo, www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 100 published by scholink inc. 2015) and bafmeng xenoliths (chenyi et al., 2017) feldspar (plagioclase and sanidine) are from basalt or products of basaltic melt crystallisation, which percolated in xenoliths. 4.3 chemical and geochemical evolution using the degree of partial melting (f) from the relation of hellebrand et al. (2001; f=10×ln(cr#)+24), we obtain 14 to 15 vol.% in lherzolites and 17 to 18 vol.% in harzburgites. the ibal-oku peridotites show high al2o3 content (2.25 and 3.74 to 4.8 wt.% in wehrlites and lherzolites respectively), coupled with high cpx modal contents (16.26 and 20.95 to 22 vol.% in wehrlites and lherzolites respectively) and lherzolite spinel cr#, depicting a fertile mantle. contrarily, cao contents are relatively low (1.57-2.28 wt.%) and harzburgite spinel cr#, characteristic of refractory rocks. this refractory character is also confirmed on the al2o3-mgo-cao triangular diagram (figure 11) where the oku rocks evolve from primordial mantle composition to the mgo enriched edge. obviously, pyroxenites show an opposite trend, likely as a result of metasomatism. in this light it is worth recalling the modal composition of these rocks which include calcite and apatite. the portion of the mantle sampled at ibal-oku is strikingly veined by diversified pyroxenites. as we pointed out in a previous section, the origin of pyroxenites is highly debated. we have however, partially discarded the magmatic origin for our samples. the presence of numerous fluid inclusions in opx and cpx crystals together with the occurrence of calcite and apatite are strong arguments for mantle metasomatism. in fact, the presence of minerals such as biotite, apatite and calcite is characteristic of modal metasomatism (pearson et al., 2003 and references there in). along the cvl, phlogopite and pargasite on contrary to that last three mineral phases are usually discuted for modal metasomatism (nana, 2001; temdjim et al., 2004; matsukage et oya, 2010; temdjim, 2012). the nature of the agents involved in the metasomatism is of chief importance and the contribution of mineral compositions (trace, ree and isotope) is paramount in the modelling of this phenomenon. in the mantle, melt and fluids circulating are of various signatures, ranging from silicic to carbonate-rich with associated co2 and brines (stagno & frost, 2010; stagno et al., 2013; frezzotti & touret, 2014). these fluids/melts enrich the mantle and modify chemical compositions, cpx will react with carbonate to produce calcite (ackerman et al., 2012). in some cases, minerals of the same nature as those present in the primary rock may be added through metasomatism, like known as ―stealth metasomatism‖ (o’reilly & griffin, 2012) which is difficult to identify but is likely accountant for the genesis of a certain number of pyroxenites. in other respects, the oku xenoliths are rich in hfse (ti, nb, hf, zr, th, u and ce), lile (rb, ba and sr) and lree (figure 7) likely significant of cryptic metasomatism as it is the case for nunivak (brown et al., 1980; pearson et al., 2003), kumba (teitchou et al., 2007), ataq (al-malabeh, 2009), nyos (temdjim, 2012) and ngao bilta (temdjim et al., in press). www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 101 published by scholink inc. figure 11. al2o3-mgo-cao diagram. primordial mantle (pm) composition after mcdonough and sun (1995) calcite and apatite represent up to 0.5 vol. % of some ibal-oku rocks. the carbon form prevailing in the mantle is depth and oxygen fugacity dependent. from the lithospheric mantle down to ca. 150 km in the asthenospheric mantle, carbon is oxidized and is present as co2 in the lithospheric mantle and as carbonate either mineral or melt, depending on the thermal regime in the asthenosphere, between approximately 90 and 150 km. beneath 150 km, the high redox state favours diamond formation and/or reduced c-h fluids if sufficient hydrogen available (hammouda & keshav, 2016). carbonates and co2-bearing minerals such as apatite (especially type a apatite which is believed to result from metasomatism by co2and h2o-rich fluids derived from a primitive mantle source region, o’reilly & griffin, 2000) are significant of patent metasomatism through carbonatitic agents. moreover, carbonatitic fluids are able to modify the modal composition by adding of diopside and olivine through reactions such as: 2mg2si2o6+camg(co3)2=camgsi2o6+2mg2sio4+2co2, producing wehrlitic fronts or channels (lustrino et al., 2016). this likely explains the origin of the wehrlites described in ibal-oku on the one hand and their generation at great depth (since the carbonate inclusions are in the crystalline state) on the other hand. cpx crystallization directly from the metasomatic agent are also reported in mantle xenoliths from the calatrava volcanic district (spain), the phenomenon occurring plausibly at greater depths in the presence of residual garnet, from peridotite or eclogite starting materials (bianchini et al., 2010). the feo contents of the ibal-oku lherzolites are high (14.15-15.05 wt. %) compared to (i) the other oku xenoliths described either on the flank at wum with a range of 9.24 to 10.8 wt. % (aziwo, 2015) or at the foot at nyos where they vary between 8.02 and 8.88 wt. % (nana, 2001; liu et al., 2017) on the one hand and (ii) many other areas along the cvl namely kumba where they are comparable to the nyos contents (8.66-8.66 wt. %, asaah unpublished data), n’gaoundere (10.20-10.38 wt. %, nkouandou et al., 2015), kapsiki (8.09-13.25 wt. %, tamen et al., 2015) on the other hand. moreover, a lot of fluid inclusions are in mineral phases and biotite crystals (fe#: 0.52-0.76) are present in peridotites. these unusual feo contents are however comparable to that of the fe-rich www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 102 published by scholink inc. lherzolite-wehrlite xenoliths from tok (ionov et al., 2005) and likely result from fe-enrichment. various elements enrichments have been described in mantle rocks worldwide. fe-improvement in particular can be achieved through either solid-state diffusion by mg-fe equilibration between mantle rocks and fe-rich cumulus veins (kempton, 1987; abe et al. 2003) or exchange with percolating melts (navon & stolper, 1987; kelemen et al., 1990, 1992; takazawa et al., 1992; nielson & wilshire, 1993; ionov et al., 2005; ackerman et al., 2009, 2013). mg-fe solid-state equilibration of the oku peridotites with their veining pyroxenites as prospective origin of fe-enrichment is uncertain for the host rocks have feo contents slightly higher than that of the pyroxenites, unless they originate from different depths, the equilibrating rocks actually missing or yet to be sampled. melt-rocks interaction potentially fits well with fe-enrichment as witnessed by comparable amounts of feo in both the peridotites and their host basaltic lavas (12.96-14.99 wt. %, asaah et al., 2015, 2019). in this case, post-entrainment modification as well as in situ long-term impregnation and equilibration can be evoked. post-entrainment enrichments are often associated with textural modification such as spongy and sieve textures, reaction borders or compositional zoning on crystals (shaw & edgar, 1997; carpenter et al., 2002; wang et al., 2012), features almost absent in the ibal-oku samples. thus, fe-enhancement through melt percolation is more likely at the origin of high feo contents. if so doing, it appears preoccupying that such a process is restricted to ibal-oku, giving the ubiquitous melt/mantle rock time and the physical contact intimacy beneath the cvl. all the xenoliths plot in silicate metasomatism field, which is also an indicator of interaction between xenoliths and silicate melt (figure 12-13). figure 12. la/sm vs la plot of the oku nodules. also included are data from the kapsiki (tamen et al., 2015) for comparison. field boundaries after ionov et al. (2002) www.scholink.org/ojs/index.php/ees energy and earth science vol. 3, no. 2, 2020 103 published by scholink inc. figure 13. relationship between ratio ca/al and mg# in clinopyroxene. carbonatitic and silicate fields are from zong et liu (2018) 5. conclusion the ibal-oku sclm is heterogenous and veined by pyroxenites. major elements in general and al2o3/cao decoupling in particular are significant of mantle enrichment/depletion. alike several sections of the mantle underlining the cvl, this sector is tectonically active and metasomatized. the metasomatism here, probably carbonatitic and silicate has acted cryptically, modally and likely stealthily. hydrous (biotite) and anhydrous (apatite and calcite) metasomatic minerals are present, feature which together with the prevalence of pyroxenites on peridotites are specific of signatures of oku sclm that deserve further consideration. acknowledgements the authors are thankful to puziewicz jacek and matusiak-małek magdalena for mineralogical analyses. they also thankful the anonymous reviewers for their constructive comments. references abe, n., takami, m., & arai, s. 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