EJBR2019v9i1art34-44 ISSN 2449-8955 European Journal of Biological Research Research Article Eur. J. Biol. Res. 2019; 9(1): 34-44 http://www.journals.tmkarpinski.com/index.php/ejbr DOI: http://dx.doi.org/10.5281/zenodo.2603912 Removal of Hydrocarbons from Crude Oil Contaminated Agricultural Soil by Phytoremediation Using Mariscus alternifolius and Fimbristylis ferruginea C. C. Chukwuma, J. C. Ikewuchi*, M. O. Monanu Department of Biochemistry, Faculty of Science, University of Port Harcourt, P.M.B. 5239, Choba, Rivers State, Nigeria * Correspondence: E-mail: ecoli240733@yahoo.com Received: 23 January 2019; Revised submission: 22 February 2019; Accepted: 21 March 2019 Copyright: © The Author(s) 2019. Licensee Joanna Bródka, Poland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/) ABSTRACT: Crude oil extraction is one major route through which hydrocarbons are released into the environment and hydrocarbon contamination is highly hazardous to the ecosystem. This study investigated the removal of hydrocarbons from crude oil contaminated agricultural soils using Mariscus alternifolius Vahl. and Fimbristylis ferruginea plant species. Before planting, the polluted soil (negative control) had a total petroleum hydrocarbon concentration of 17962.11±1000.00 mg/kg and polycyclic aromatic hydrocarbon concentration of 440.97±1.00 mg/kg. Likewise, the soil oil and organic carbon contents were 3.25±0.10 ppm and 3.06±0.02% respectively. Results, 90 days after planting, indicated a significant decrease in the total petroleum hydrocarbon concentrations of M. alternifolius (100.82±46.31 mg/kg) and F. ferruginea (110.41±39.68 mg/kg) treated soils. Likewise, there was a significant decrease in the polycyclic aromatic hydrocarbon concentration of M. alternifolius treated soil (95.69±65.44 mg/kg). The oil content of the treated soils significantly decreased to 1.03±0.28 ppm and 0.84±0.33 ppm in M. alternifolius and F. ferruginea treated soils respectively, while the organic content of the treated soils significantly decreased to 2.16±0.09% and 2.20±0.20% in M. alternifolius and F. ferruginea treated soils respectively. Phytoremediation using M. alternifolius and F. ferruginea has proven to be potent in the remediation of hydrocarbon contaminated soil through enhancement and recovery of the polluted soil. These plant species which improved the cultivation and germination competence of the treated soils thus making the soil probable for agricultural and other related purposes are therefore recommended for used in the phytoremediation of crude oil contaminated soils. Keywords: Crude oil; Polluted soil; Hydrocarbons; Fimbristylis ferruginea; Mariscus alternifolius. 1. INTRODUCTION Crude oil is a complex mixture of organic compounds predominated by carbon and hydrogen atoms albeit containing smaller amounts of nitrogen, oxygen, sulfur and tinges of metallic constituents [1]. Its formation is a natural process resulting from geological deposits formed from organic decomposition products of ancient plants and animals under high temperature and pressure [2]. Crude oil extraction is one major route through which hydrocarbons are released into the environment. Such release sometimes emanates due to exploration, mining, transportation, pipeline rupture, or damage by saboteurs and hoodlums [3]. Hydrocarbon contamination is highly hazardous to the ecosystem and poses severe impact on plants and animals including human health [4]. This is because on reaching the environment, Chukwuma et al. Removal of hydrocarbons from crude oil contaminated agricultural soil by phytoremediation 35 Eur. J. Biol. Res. 2019; 9(1): 34-44 http://www.journals.tmkarpinski.com/index.php/ejbr petroleum hydrocarbons bind to soil components [5] causing biological damages by destructing the supply of water, nutrients, oxygen and light, hence, affecting soil fertility, plant growth and germination and making the soil unsuitable for agricultural and other investment purposes [4]. Pollution can result to imbalance in carbon- nitrogen ratio at site of spillage owing to the conglomeration of carbon and hydrogen in crude oil. Elevated levels of organic compounds on soil surface deplete oxygen reserves and diminish rates at which oxygen diffuses into deeper layers [6-7]. The fate and spread of petroleum hydrocarbons on subsurface is dependent on viscosity of the oil and its quantity. In soil, the fate of petroleum hydrocarbons is affected by the composition, chemical and physical properties of the soil as well as composition of the petroleum products. Likewise, the biodegradability of these petroleum hydrocarbons can be influenced by the availability and concentration of the contaminants. Petroleum hydrocarbons can be sequestered and fractionated within the soil via organic matter sorption or diffuse into the three dimensional structure of the organic matter. Thus, there is a proportional reduction in contaminant extraction and biodegradation as the interaction between particles of soil and pollutants increase [8]. Recently, the use of plants and associated microbes to decontaminate polluted soil has gained wide interest. This remediation technique, phytoremediation, established on the view of using nature to cleanse nature has been effectively used to tackle pollutants such as heavy metals and hydrocarbons [9]. Plants employ the mechanism of rhizospheric degradation of pollutants such as hydrocarbons that promote the increase in the microbial population in the root zone which sequentially breaks down pollutants [10]. Microorganisms are ubiquitously located almost in every part of the terrestrial ecosystem and are important in ecological and biodegradation functional processes in polluted soils [11]. They are furnished with metabolic machinery that enables them to utilize petroleum products as a carbon and energy source. There are enormous benefits of relying on indigenous microorganisms to degrade hydrocarbons. Foremost, natural populations must have evolved and developed through many years. These microorganisms adapt for survival and proliferation in that environment. Secondly, the capableness to utilize hydrocarbons is disseminated among a diverse microbial population. This population prevails in natural ecosystems and either independently or synergistically metabolizes several hydrocarbons [12]. This study was performed to ascertain the competence of Mariscus alternifolius Vahl. and Fimbristylis ferruginea in the removal of hydrocarbons from crude oil polluted agricultural soil. 2. MATERIALS AND METHODS 2.1. Experimental design Crude oil polluted agricultural farmland, with over 10 years oil spill history, was identified in Bodo community of Ogoniland, Nigeria. A portion of the farmland was mapped and assessed to ascertain prevailing and physicochemical factors inherent in the site. Likewise, the prevailing indigenous plant community of the site was determined following collection and identification of the plant species. Two species: Mariscus alternifolius Vahl. and Fimbristylis ferruginea, were selected after the identification based on existing literature on their effectiveness in surviving and proliferating in extremely harsh soil environment and the scanty report on their phytoremediation capability. Mature and viable seeds of M. alternifolius and F. ferruginea were collected from the wild for nursery. Unpolluted soil for nursery which also served as the negative control soil in the study was collected from an agricultural farmland located in the premise of the University of Port Harcourt with no history of pollution while the polluted soil (positive control) was collected from the spill site. Collection was carried out using sterile airtight plastic bags and taken to Ecological Centre of the University of Port Harcourt for pot experiment study. The propagated seeds for nursery, at seedling level, were transferred into 8 kg pots containing polluted soils set up in triplicate. Each pot contained 4 seedlings. Non-vegetated positive and negative controls were likewise set up in triplicate and Chukwuma et al. Removal of hydrocarbons from crude oil contaminated agricultural soil by phytoremediation 36 Eur. J. Biol. Res. 2019; 9(1): 34-44 http://www.journals.tmkarpinski.com/index.php/ejbr placed under same condition and in proximity with the treatment groups, totaling 12 pots employed for the study. 2.2. Laboratory analyses The total petroleum hydrocarbons (TPH) analysis followed EPA 8260c [13] and International Organization for Standardization ISO 16703 [14] standard methods. Polycyclic aromatic hydrocarbons (PAH) analysis followed EPA 8270 standard method as adopted [15-16]. Oil content was determined by the toluene extraction method [17-18]. Organic carbon was ascertained by loss of weight on ignition method while the pH of the soil samples was determined using a calibrated pH meter [19]. Moisture content determination followed the gravimetric method as described by [20]. Vapour phase transfer method [21-22] was employed for Hydrocarbon Utilizing Bacteria (HUB) and Fungi (HUF) estimation following decimal dilutions (10-fold) of the soil suspensions inoculated onto duplicate sterile Petri dishes containing mineral salt agar (MSA). The germination toxicity test was carried out by the method [22] using hydrocarbon sensitive plant seed, lettuce (Lactuca sativa L.). 2.3. Statistical analysis Statistical analysis was carried out using the MS Excel and SPSS 20.0. Sampling and chemical analyses were examined in triplicate in order to decrease the experimental errors and to increase the experimental reproducibility, with results expressed as means ± standard deviation of the triplicate determinations. Using One way analysis of variance (ANOVA), data between groups were determined by the Bonferroni test at 95% (p<0.05) confidence level while data between periods were determined by the Student t-test. 3. RESULTS AND DISCUSSION The total petroleum hydrocarbons (TPH) of M. alternifolius and F. ferruginea treated soils are presented in Table 1. The polluted soil (negative control) before planting had TPH concentration of 17962.11±1000.00 mg/kg. This value was within the range of 126 to 52,200 mg/kg reported by United Nations Environment Programme (UNEP) along Shell Petroleum Development company (SPDC) pipeline rights of way in Ogoniland, Rivers State, Nigeria but falls above regulatory limits [23] target values of 50 mg/kg in farmland. The TPH concentrations of the treated soils, ninety days after planting (90 DAP), indicated M. alternifolius treated soil had TPH concentration of 100.82±46.31 mg/kg while F. ferruginea treated soil had TPH concentration of 110.41±39.68 mg/kg. Likewise, the polycyclic aromatic hydrocarbons (PAH) concentration of the polluted soil before planting as shown in Table 2, revealed PAH concentration of 440.97±1.00 mg/kg. This value falls above regulatory limits [23] target value of 1 mg/kg in farmlands. The PAH of the treated soil groups, 90 DAP, further revealed M. alternifolius treated soil had PAH concentration of 95.69±65.44 mg/kg while F. ferruginea treated soil had PAH concentration of 184.09±180.29 mg/kg. These findings corroborate the report [24] of reduced hydrocarbon concentration of petroleum hydrocarbon in oil impacted soil using Axonopus sp. and associated microorganisms. Likewise, Nwaichi et al. [25] reported similar significant decrease in PAH using Fimbristylis littoralis, Hevea brasilensis, Cymbopogom citratus, and Vigna subterranean. This finding further agrees with the reports [26-27] that phytoremediation can be successfully used to manage soil contaminated with petroleum hydrocarbons. As could be observed in Tables 1 and 2, it may be pertinent to assert that natural biological processes could play important role in hydrocarbon reduction. If this is true, it may however account for the TPH concentration of 53.13±13.08 mg/kg and PAH concentration of 27.64±18.13 observed in the negative control 90 DAP albeit no significant difference (p<0.05) existed between this group and the others. This natural attenuation may have been hastened by atmospheric influence [26]. This finding agrees with previous reports Chukwuma et al. Removal of hydrocarbons from crude oil contaminated agricultural soil by phytoremediation 37 Eur. J. Biol. Res. 2019; 9(1): 34-44 http://www.journals.tmkarpinski.com/index.php/ejbr [28-32] on hydrocarbon degradation ability by natural attenuation. Similarly, pH, oxygen (aeration), soil nutrients, temperature, soil moisture, soil enzymes and various microorganisms can enhance hydrocarbon biodegradation [1] with previous reports [33-36] confirming this assertion. The percentage recovery [1, 3] of the polluted soil further revealed a failure in restoration as regards both TPH and PAH. The oil content of M. alternifolius and F. ferruginea treated soils are presented in Table 3. The polluted soil (negative control) before planting had oil content concentration of 3.25±0.10 ppm. Nonetheless, a significant decrease in oil content of the treated soils was recorded over time. The oil content of the treated soil groups, 90 DAP, revealed a decrease to 1.03±0.28 ppm and 0.84±0.33 ppm in M. alternifolius and F. ferruginea treated soils, respectively. This result corroborates the report [1] of a similar decrease in oil content over time. Such degradation process follows a shifting order (1-0) [37]. With regards to oil content, by 30 and 60 DAP, the treatments restored the polluted soils towards normalcy (14.12, 7.07 and 0.54%). By 90 DAP the treatment using F. ferruginea restored the polluted soil towards normal value (2.47%). However, the value for the treatment using M. alternifolius nosedived indicating a failure in restoration. Table 1. Total petroleum hydrocarbon (TPH) (in mg/kg) of the treated soils and their corresponding controls. Group BP 90 DAP % R 90 DAP Positive control 17.57±1.00a 33.32±0.10a,* NA Negative control 17962.11±1000.00b 53.13±13.08a,* NA M. alternifolius 17962.11±1000.00b 100.82±46.31a,* -240.74 F. ferruginea 17962.11±1000.00b 110.41±39.68a,* -289.148 Values are mean ± standard deviation of triplicate determination. Values in the same column with different letters (a, b...) are significantly different at p<0.05. *p<0.05 compared to the corresponding values before planting. Note: BP = Before Planting; WAP = Week(s) After Planting; NA = Not Applicable. Table 2. Polycyclic aromatic hydrocarbon (PAH) (in mg/kg) of the treated soils and their corresponding controls. Group BP 90 DAP % R 90 DAP Positive control 5.80±0.10a 9.0368±0.49a,* NA Negative control 440.97±1.00b 27.64±18.13a,* NA M. alternifolius 440.97±1.00b 95.69±65.44a,* -365.77 F. ferruginea 440.97±1.00b 184.09±180.29a -840.88 Values are mean ± standard deviation of triplicate determination. Values in the same column with different letters (a, b...) are significantly different at p<0.05. *p<0.05 compared to the corresponding values before planting. Note: BP = Before Planting; WAP = Week(s) After Planting; NA = Not Applicable. Table 3. Oil content (in ppm) of the treated soils and their corresponding controls. Group BP 30 DAP 60 DAP 90 DAP % R 30 DAP % R 60 DAP % R 90 DAP Positive control 0.13±0.01a 0.09±0.01a* 0.06±0.12a,* 0.05±0.01a,* NA NA NA Negative control 3.25±0.10b 2.71±0.40b* 1.90±0.17b,c,* 0.86±0.09b,c,* NA NA NA M. alternifolius 3.25±0.10b 2.34±0.20b* 1.77±0.42b,* 1.03±0.28b,* 14.12 7.07 -20.99 F. ferruginea 3.25±0.10b 2.34±0.24b* 1.89±0.03c,* 0.84±0.33c,* 14.12 0.54 2.47 Values are mean ± standard deviation of triplicate determination. Values in the same column with different letters (a, b...) are significantly different at p<0.05. *p<0.05 compared to the corresponding values before planting. Chukwuma et al. Removal of hydrocarbons from crude oil contaminated agricultural soil by phytoremediation 38 Eur. J. Biol. Res. 2019; 9(1): 34-44 http://www.journals.tmkarpinski.com/index.php/ejbr Note: BP = Before Planting; WAP = Week(s) After Planting; NA = Not Applicable. Table 4 reveals the Organic carbon (OC) content of the treated soils with their corresponding controls. The organic carbon content of the polluted soil (negative control) was significantly higher (p<0.05) than the unpolluted soil (positive control). This finding corroborates some previous reports [18, 38-40] and such observed difference may be due to metabolic processes following the oil spill that facilitate agronomical addition of organic carbon from petroleum hydrocarbon [38, 41]. The decrease in organic carbon content of the treated soils over time (see Table 4) agrees with the report [42] which showed similar changes in total organic carbon during bioremediation of crude oil impacted soil. According to Tanee and Albert [43], increased microbial population implies increased energy (carbon) demand since the microbial oil degraders use the carbon content for the provision of energy. With regards to organic carbon, the treatments, 30 DAP, nosedived indicating failure in restoration. However, by 90 DAP, treatments using M. alternifolius and F. ferruginea restored the polluted soil towards normalcy at 10.40 and 5.58% respectively. Table 4. Organic carbon (OC) (in %) of the treated soils and their corresponding controls. Group BP 30 DAP 90 DAP % R 30 DAP % R 90 DAP Positive control 1.64±0.10a 1.60±0.35a 1.35±0.15a,* NA NA Negative control 3.06±0.02b 2.69±0.23b 2.25±0.17b,* NA NA M. alternifolius 3.06±0.02b 2.77±0.23b 2.16±0.09b,* -7.03 10.40 F. ferruginea 3.06±0.02b 2.75±0.07b,* 2.20±0.20b,* -5.50 5.58 Values are mean ± standard deviation of triplicate determination. Values in the same column with different letters (a, b...) are significantly different at p<0.05. *p<0.05 compared to the corresponding values before planting. Note: BP = Before Planting; WAP = Week(s) After Planting; NA = Not Applicable. The pH of the treated soils and the corresponding controls (Table 5) revealed a significant decrease in the pH of the polluted soil (negative control) before planting when compared with the unpolluted soil (positive control). This finding corresponds with reports [44-45] on positive correlation between acidic pH and crude oil concentration in soil and opined that crude oil pollution could make soils acidic thereby increasing the toxicity of the soil. The pH values (5.50±0.42 and 5.50±0.04) of the treated soils obtained 90 DAP agrees with Hatami et al. [46] who reported a decrease in pH of soil samples treated with alfalfa powder and associated such a decrease with the release of organic acids during decomposition process. This is because organic matter is capable of lowering pH by releasing H+ associated with organic anions or through nitrification process [47]. Nonetheless, the obtained pH values fall within the standard limit of 5.5 to 6.5 as stipulated [23]. Table 5. pH of the treated soils and their corresponding controls. Group BP 30 DAP 60 DAP 90 DAP Positive control 6.75±0.10a 6.71±0.74a 6.43±0.32a,* 6.46±0.11a Negative control 5.69±0.10b 5.81±0.47a 5.71±0.30b 5.55±0.42b M. alternifolius 5.69±0.10b 6.08±0.78a 5.91±0.61a,b 5.50±0.42c F. ferruginea 5.69±0.10b 6.19±1.15a 5.72±0.34b 5.50±0.04b,c,* Values are mean ± standard deviation of triplicate determination. Values in the same column with different letters (a, b...) are significantly different at p<0.05. *p<0.05 compared to the corresponding values before planting. Note: BP = Before Planting; WAP = Week(s) After Planting; NA = Not Applicable. Chukwuma et al. Removal of hydrocarbons from crude oil contaminated agricultural soil by phytoremediation 39 Eur. J. Biol. Res. 2019; 9(1): 34-44 http://www.journals.tmkarpinski.com/index.php/ejbr The moisture content of the treated soils as shown in Table 6 revealed a significant decrease in moisture content of the polluted soil (negative control) when compared with unpolluted soil (positive control) before planting. This result agrees with Essien and John [48] who reported significantly low moisture content in polluted soil compared to unpolluted soil. It has also been reported that high crude oil concentrations in soil could clog soil pores and reduce water and oxygen penetration [49-50]. According to Abosede [51], crude oil might have negative effects on some soil physical properties such as decreased pore spaces. This may be due to the presence of less dissolved materials present for plant uptake and subsequent metabolism, as well as the blockage of soils emanating from crude oil contamination of the soil. It has been reported that crude oil spillage reduces soil moisture availability or holding capacity, or increase moisture deficit in agricultural soils thereby damaging plant growth and yield [52]. The observed increase in the moisture content of the treated soils agrees with the reports [44, 53, 54]. Since crude oil can bind soil particles together [44] and decrease water permeability, such an increase in moisture content may be a result of the decrease in hydrocarbon contents of the soil. Table 6. Moisture content (in %) of the treated soils and their corresponding controls. Group BP 30 DAP 60 DAP 90 DAP Positive control 10.33±0.10a 21.00±3.18a,* 7.55±2.34a 19.11±1.95a,* Negative control 9.67±0.01b 5.89±0.38b,* 17.11±1.64b,* 28.33±0.67b,* M. alternifolius 9.67±0.01b 13.44±1.84c,* 17.11±1.17b,* 16.33±2.52c,* F. ferruginea 9.67±0.01b 13.56±2.50c,* 15.89±2.27b,* 21.00±2.02a,c,* Values are mean ± standard deviation of triplicate determination. Values in the same column with different letters (a, b...) are significantly different at p<0.05. *p<0.05 compared to the corresponding values before planting. Note: BP = Before Planting; WAP = Week(s) After Planting; NA = Not Applicable. Table 7. Hydrocarbon utilizing bacteria (HUB) (in Log10 cfu/g) of the treated soils and their corresponding controls. Group BP 45 DAP 90 DAP Positive control 4.38±0.16 a 5.04±0.31 a 6.32±0.20 a,* Negative control 4.81±0.01 b 5.41±0.01 a,* 6.91±0.10 b,* M. alternifolius 4.81±0.01 b 5.67±0.25 a 6.87±0.06 b,* F. ferruginea 4.81±0.01 b 5.60±0.20 a* 6.85±0.06 b,* Values are mean ± standard deviation of triplicate determination. Values in the same column with different letters (a, b...) are significantly different at p<0.05. *p<0.05 compared to the corresponding values before planting. Note: BP = Before Planting; WAP = Week(s) After Planting; NA = Not Applicable. The microbiological profiles of the treated soils are presented in Tables 7 and 8. The polluted soil (negative control) before planting had hydrocarbon utilizing bacteria (HUB) of 6.50×104 cfu/g as compared to 2.42×104 cfu/g contained in the unpolluted soil (positive control) (Table 7). Likewise, the polluted soil (negative control) before planting had hydrocarbon utilizing fungi (HUF) of 6.45×104 cfu/g as against 3.20×103 cfu/g recorded in the unpolluted soil (positive control) (Table 8). These results agree with the findings [22, 55] which showed higher population of crude oil degrading microbes in the polluted soils than the unpolluted soils and associated such a difference with the presence of crude oil which could boost carbon supply in the soils and therefore favour the growth of the organisms including certain changes in the physicochemical properties of the soils especially the provision of essential nutrients required for microbial growth. According to Ataikiru et al. [21], it is known that colony forming unit (cfu) counts are higher in Chukwuma et al. Removal of hydrocarbons from crude oil contaminated agricultural soil by phytoremediation 40 Eur. J. Biol. Res. 2019; 9(1): 34-44 http://www.journals.tmkarpinski.com/index.php/ejbr polluted soil than unpolluted soil and microbial counting of a contaminated site is the easiest method that can be employed for bioremediation. As could be observed (See Tables 7 and 8), the significant increase in bacteria and fungi count over time agrees with some findings [1, 56, 57]. This may be an indication of increased biodegradation and utilization of the hydrocarbons by the microbial community [1]. Table 8. Hydrocarbon utilizing fungi (HUF) (in Log10 cfu/g) of the treated soils and their corresponding controls. Group BP 45 DAP 90 DAP Positive control 3.51±0.16 a 4.27±0.18 a,* 5.34±0.08 a,* Negative control 3.81±0.01 b 4.75±0.13 a,b,* 5.69±0.04 b,* M. alternifolius 3.81±0.01 b 4.80±0.08 b,* 5.65±0.14 b,* F. ferruginea 3.81±0.01 b 4.99±0.27 a 5.70±0.14 a,b,* Values are mean ± standard deviation of triplicate determination. Values in the same column with different letters (a, b...) are significantly different at p<0.05. *p<0.05 compared to the corresponding values before planting. Note: BP = Before Planting; WAP = Week(s) After Planting; NA = Not Applicable. The higher percentage germination recorded in the treated soils compared to the corresponding negative control (See Table 9) indicated that the treatment of the soils with the plants species improved the soil germination capacity. This finding corroborates Chukwuma et al. [1] who reported the germination of lettuce seed in crude oil polluted soil treated with Schwenkia americana L. and Spermacoce ocymoides Burm. f. Likewise, Abioye et al. [33] reported seed germination on remediated soil previously contaminated with lubricating oil. Although the TPH and PAH levels of the negative control were higher than those of the treated soils after the 90 days treatment, and given that lettuce is hydrocarbon sensitive, it could be that the treatment plants secreted exudates which potentially impacted the soil thus providing the treated soils with properties that enhanced the germination of the lettuce in the treated soils. It may however be that the removal of pollutants, other than hydrocarbons, was enhanced more in the treated soils. Table 9. Germination toxicity test of the treated soils and their corresponding controls. Group Percentage Germination (%) Percentage Germination Index (%) % R Percentage Germination (%) Positive control 95.00±5.00 a NA NA Negative control 68.33±2.89b NA NA M. alternifolius 80.00±5.00c 67.00±7.21b 43.75 F. ferruginea 80.00±5.00c 69.00±7.00b 43.75 Values are mean ± standard deviation of triplicate determination. Values in the same column with different letters (a, b...) are significantly different at p<0.05. *p<0.05 compared to the corresponding values before planting. Note: BP = Before Planting; WAP = Week(s) After Planting; NA = Not Applicable 4. CONCLUSION The application of M. alternifolius and F. ferruginea plant species has proven to possess the potential for remediation of hydrocarbon contaminated soil through the enhancement and recovery of the polluted soil and improved the cultivation and germination competence of the treated soils thus making the soil probable for agricultural and other related purposes. 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