Microsoft Word - 10-277-287-PJAEC-03082021-388-C-Revised Galley Pro Cross Mark ISSN-1996-918X Pak. J. Anal. Environ. Che m. Vol. 23, No. 2 (2022) 277 – 287 http://doi.org/10.21743/pjaec/2022.12.10 Valuation of Groundwater Contaminated with Nitrates and Human Health Risks (HHR) Between Villages of Sinjar and Tal Afar Districts, Iraq Mohammed Hazim Sabry Al-Mashhadany College of Education for Pure Sciences, University of Mosul, Mosul, Iraq. *Corresponding Author Email: Mohammedhazemm@uomosul.edu.iq Received 03 August 2021, Revised 28 October 2022, Accepted 01 November 2022 -------------------------------------------------------------------------------------------------------------------------------------------- Abstract Nitrates are one of the most common pollutants in groundwater. To assess the risk of exposure to nitrates in drinking water for age groups, we monitored the concentration of nitrates in the drinking water of the Al-Jazeera region. The climate of this region is characterized as dry and semi-arid, and its inhabitants depended on the water in the aquifers as a source of drinking for many years, without monitoring, treatment, or filtration system, as there is no public drinking water network. A model was also used to assess the risks of nitrate pollution in groundwater to human health. Samples were taken from 30 wells distributed equally over the three villages to collect water samples and measure the concentration of nitrate ions in groundwater. The concentration of nitrate ions in well water is less than 50 mgL-1 and ranged between (4.2 – 48.1) mgL-1. The mathematical model results showed that the ages under 11 years and pregnant wo men have a higher hazard quotient of nitrate value (HQ) than one except for wells No. 2 and 9, which are higher than the permissible limits for drinking. As for age groups above 11, well water was suitable for drinking, and the HQ value was mainly less than one. The reason for this age group's lower chronic daily intake (CDI). In other words, the groundwater was suitable for adults and not for children under 11 years and pregnant women. Keywords: HQ, CDI, Nitrate, Cancer, Drinking water. -------------------------------------------------------------------------------------------------------------------------------------------- Introduction The issue of the environment and environmental pollution has received the attention of specialists and global public opinion, and there have been many studies that dealt with groundwater pollution after it was contaminated with chemical, and biological pollutants, which has contributed greatly to the increase in diseases and the deterioration of environmental components [1]. The use of well water regardless of the degree of pollution and the severity of their use, leads to diseases that may be fatal, and these diseases may not appear when using water until some time has passed; pollution of groundwater with nitrates is an important problem for the rural population of the world, as there are hundreds of wells and tens of thousands of hectares of agricultural land whose groundwater cannot be used for drinking purposes due to nitrate pollution, as in Morocco [2], Germany [3], and France [4, 5]. Therefore cannot use its water to exceed the nitrate concentrations permissible limit [6]. From the above, we note the magnitude of the problem, considering the negative effects of pollution on general human health and infants in particular. The health effects of nitrates in humans are most closely related to Pak. J. Anal. Environ. Che m. Vol. 23, No. 2 (2022) 278 infants, as their consumption of water containing nitrates with milk leads to the transformation in the stomach that can combine with oxygen molecules in red blood cells leading to oxygen depletion and the possibility of suffocating the child. As for adults, drinking water containing higher concentrations of nitrates than infants may not pose a health risk [7, 8]. However, some studies indicate the possibility of bleeding in the spleen due to the ingestion of water containing large amounts of nitrates. World health organization (WHO) standards state that nitrate concentrations exceeding 50 mgL-1 can be dangerous for adults and children; also, a low nitrate content can become hazardous when the water containing it boils because nitrites and nitrates are not evaporable [9, 10]. The concentration of nitrates in groundwater and surface water is normally low. Still, it may reach High levels due to various nitrogen sources, whether (agricultural or animal) on the earth's surface, in the soil layer, or the shallow layers under the soil, which is transmitted by the filtration process, surface runoff, or others [11, 12]. When the added quantities of chemical fertilizers exceed certain proportions, this often happens through repeated, unexamined, and random additions in many countries, leading to many negative effects, directly or indirectly, on the biological system in particular and the environment in general. The direct repercussions of chemical fertilizers are Direct damage to the living components of the ecosystem, including human, animal, and plant health. As for the indirect effects, they negatively affect the vital parts of the ecosystem (water, air, and soil). They occur in a defect in the composition of these natural components and the natural balance between them. On the other hand, the leakage of nitrates into the groundwater is one of the most important risks of pollution with nitrogen fertilizers [13, 14]. In some countries where groundwater is the main source of drinking. Some reports indicate groundwater pollution increases the risk of cancer of the pancreas, brain, large intestine, bladder, and thyroid [15, 16]. Geospatial technology, such as satellite remote sensing, geographic information systems (GIS), and satellite navigation system, are widely used in groundwater research. The most common applications of geospatial technology in groundwater research include identifying and mapping groundwater exploration areas and producing spatial and sensitive groundwater quality for pollution maps using GIS [17]. Among the studies that were conducted was to measure the concentration of nitrates in groundwater, which are dangerous to human health: Noor and others studied the nitrate ion concentration in the groundwater of several wells in the city of Mosul, whose concentration ranged between (0.39-10.88 mgL-1) attributed this to pollution with wastewater [18], and the study of Al-Saffawi and Awad of the village of Abuwajnah Village in the Zammar sub-district in Nineveh Governorate indicated that there is no risk of drinking water by rural consumers due to its low concentrations, as its HQ value ranged between (0.0228 - 0.1125) [19]. The study aims to find out the suitability of drinking water for different age groups by applying the nitrate model. Material and Methods Description of the Study Area The study was conducted on groundwater in the northwestern part of Nineveh Governorate (Al-Jazirah region). It includes the Kakhirta village, the village of Ein Al-Hussan and the village of Shoueira, where various agricultural and animal activities are spread that depend on the groundwater sources in the area for drinking and various uses [1, 20]. Pak. J. Anal. Environ. Che m. Vol. 23, No. 2 (2022)279 Sample Collection Samples were collected regularly for five months to cover part of the area, and GPS determined the coordinates of each well. From there, they were projected onto the map as identified 30 wells. Table 1 shows the number of wells and samples collected from the sites according to geographical division. The total number of samples taken was 150 during the study period, with a sample from each well for each month. Table 1. Coordi nates (E, N) and al titude of the studied wells. Sample Preparation At 220 nm, the nitrate ion absorbs UV light, but not at 275 nm. Because dissolved organic stuff absorbs light at 220 nm, this is achieved by measuring the absorbance of a water sample at 275 nanometers, a wavelength at which organic matter can absorb electromagnetic radiation but not by nitrates. Once known, an experimental correction factor at 220 nm can discriminate between nitrate and organic matter. There are two phases to sample preparation. The sample will first be filtered to prevent UV light from being scattered by suspended particles in the water sample. To avoid interferences caused by the absorption of OH - or CO3 2- , both of which may absorb at 220 nm, the samples were acidified with 1 N HCl. Up to 1000 CaCO3 mgL -1 , acidification should preclude interference from these ions. Hydrochloric acid is employed because Cl- does not absorb light in the spectrum's 250 – 290 nm region. Samples were collected for five replicates of each sample in pyrex glass containers of 250 ml capacity and routinely followed the standard method for taking samples from the source as they filled the sample. The air was expelled inside the package, sealed after washing the container twice or three from the same source, and transferred to the Industrial Chemistry Lab at the University of Mosul. The measurement was carried out according to the (Ultraviolet screening method) by taking a known volume of the well-filtered sample, then adding to it (1 mL) of HCl (1 N) acid and measured at wavelengths of 220 and 275 nm using a UV spectrophotometer [21]. Assessment of the Human Health Risk of Nitrates (HHR) by Drinking Water for the Studied Wells Well water was evaluated for the studied area HHR, according to the United States Environmental Protection Agency Well E N Al titude (m) 1 42̊ 34ʹ88ʹʹ 36˚55ʹ90ʹʹ 406 2 42̊ 34ʹ71ʹʹ 36˚55ʹ87ʹʹ 406 3 42̊ 34ʹ93ʹʹ 36˚55ʹ73ʹʹ 407 4 42̊ 34ʹ45ʹʹ 36˚55ʹ68ʹʹ 406 5 42̊ 34ʹ59ʹʹ 36˚55ʹ45ʹʹ 407 6 42̊ 34ʹ95ʹʹ 36˚55ʹ60ʹʹ 407 7 42̊ 35ʹ01ʹʹ 36˚55ʹ34ʹʹ 407 8 42̊ 34ʹ68ʹʹ 36˚55ʹ31ʹʹ 407 9 42̊ 34ʹ70ʹʹ 36˚55ʹ12ʹʹ 407 K ak h ir ta v il la g e 10 42̊ 35ʹ00ʹʹ 36˚55ʹ06ʹʹ 407 11 42̊ 21ʹ79ʹʹ 36˚31ʹ16ʹʹ 335 21 42̊ 21ʹ53ʹʹ 36˚31ʹ43ʹʹ 335 13 42̊ 21ʹ42ʹʹ 36˚31ʹ64ʹʹ 335 14 42̊ 21ʹ47ʹʹ 36˚30ʹ26ʹʹ 332 51 42̊ 21ʹ26ʹʹ 36˚31ʹ26ʹʹ 332 61 42̊ 21ʹ11ʹʹ 36˚31ʹ11ʹʹ 342 71 42̊ 20ʹ87ʹʹ 36˚32ʹ02ʹʹ 348 81 42̊ 21ʹ13ʹʹ 36˚32ʹ08ʹʹ 348 91 42̊ 22ʹ19ʹʹ 36˚30ʹ54ʹʹ 327 E in A l- H us sa n vi ll ag e 20 42̊ 22ʹ18ʹʹ 36˚31ʹ02ʹʹ 335 12 42˚22'86'' 36˚28'61'' 324 22 42˚24'04'' 36˚29'34'' 313 23 42˚24'24'' 36˚28'75'' 317 24 42˚24'26'' 36˚27'66'' 318 25 42˚24'94'' 36˚26'57'' 310 26 42˚25'01'' 36˚25'01'' 308 27 42˚22'80'' 36˚26'08'' 320 28 42˚25'59'' 36˚30'07'' 325 29 42˚26'53'' 36˚29'59'' 319 S h o u ei ra v il la g e 30 42˚26'32'' 36˚26'80'' 304 Pak. J. Anal. Environ. Che m. Vol. 23, No. 2 (2022) 280 (USEPA), which is widely used to determine the risks of nitrates to human health. A special model was used to calculate the nitrate concentration in well water. This model calculates the CDI and the HQ or the following equations: CDI = Sw × IS × ES × DE / BZ × ZT HQ = CDI / DN CDI stands for chronic daily intake (mg/kg day), and Sw stands for nitrate content in drinking water (mgL -1 ). DE indicates the exposure period in years and IS represents the average daily intake of water (liters) for different ages of adults, children, and babies. The local population in the study region relies on groundwater for drinking. Therefore, the frequency of exposure (ES) is 365 days/year. BZ: Average body weight in kg, meantime values (ZT) in days, DN represents the reference dose of nitrates (1.6 mg/kg/d), and these data are obtained from Risk Information Systems. If the HQ values are more than one, then it is considered hazardous to human health, and water is not suitable for drinking, but when it is equal to or less than one, drinking water is not dangerous and can be used for drinking [22, 23]. Inverse Distance Weighting Used the (IDW) method to predict the spatial distribution of nitrates in the groundwater of 30 wells, one of the geostatistical methods and one of the most advanced techniques. Fig 2, 3 and 4 show the distribution of nitrates in groundwater over the area of each village [24]. Figure 1. Village sites i n the study area in Ni neveh Governorate [23, 24] Kakhirta village Ein Alhussan village Shawira village Tal Afar district Pak. J. Anal. Environ. Che m. Vol. 23, No. 2 (2022)281 Figure 2. Spati al distri bution of nitrates i n the Kakhi rta vill age Figure 3. Spati al distri bution of nitrates i n the Ei n Al -Hussan vill age Pak. J. Anal. Environ. Che m. Vol. 23, No. 2 (2022) 282 Figure 4. Spati al di stri bution of nitrates i n the Shoueira vill age Results and Discussion Nitrogen fertilization is one of the most important agricultural applications that contribute to the pollution of groundwater, which causes health risks, including the carcinogenic effect. So, the amount of nitrates that a person takes in a day should not exceed 200 mg, since nitrates in the body are transformed into nitrites and are toxic through the formation of amines (nitrosamines) [25], which in turn cause liver cancer or esophageal cancer, Nitroso compounds are formed in the human body due to the intake of nitrates [26]. After drinking water containing nitrates, about 20% is converted to nitrite by bacteria in the digestive system. The nitrates in the acid conditions of the stomach turn into nitroso- acid (HNO2), which reacts with the amines to form N-nitroso compounds (NOCs) that may cause cancer when present in high concentrations [27]. The results in this study showed values of nitrate concentration in well water, which ranged between (4.2 - 48.1) mgL -1 , and their means do not exceed 47 mgL-1, meaning it is less than 50 mgL -1 Table 2, The rise is due to the intrusion of animal and agricultural waste into the groundwater. As a result of the Pak. J. Anal. Environ. Che m. Vol. 23, No. 2 (2022)283 biodegradation processes by microorganisms, the amino acids are transformed into ammonia and then into nitrates by the nitrification process, as in the following equation: 42 NHRNH 324 NONONH Table 2. Ni trate ion val ues for the studied water wells (mgL-1). Wells Mi n Max Mean ± SD 1 19.3 48.0 40.7±12.0 2 4.2 31.0 24.5±11.4 3 20.0 47.0 41.1±11.8 4 18.9 45.2 37.4±10.5 5 20.2 48.0 41.5±11.9 6 20.0 48.0 41.4±11.9 7 17.6 45.2 38.9±11.9 8 20.0 45.8 36.9±12.1 9 6.5 34.8 26.8±12.0 K ak h ir ta v il la g e 10 19.9 46.5 40.7±11.6 11 45.5 47.7 46.6±0.8 12 45.5 47.6 46.7±0.8 13 45.7 47.1 46.4±0.6 14 46.1 47.4 46.7±0.6 15 43.0 45.4 44.4±1 16 39.6 45.8 43.4±2.9 17 43.8 46.8 45.1±1.2 18 44.2 46.2 45.1±0.9 19 45.5 47.2 46.3±0.7 E in A l- H u ss an V il la g e 20 45.8 47.0 46.4±0.6 21 43.2 46.3 44.8±1.3 22 43.3 46.5 45.2±1.3 23 46.1 47.6 46.8±0.6 24 45.6 47.4 46.6±0.7 25 45.7 47.6 46.5±0.8 26 45.0 47.7 46.5±1 27 46.1 48.1 47.0±0.8 28 45.3 47.6 46.7±0.9 29 45.3 47.7 46.6±0.9 S h o u ei ra V il la g e 30 44.2 45.9 44.9±0.8 These values are considered permissible for drinking according to the standards of the World Health Organization (WHO). The harmful effect of the nitrate ion appears through the presence of methemoglobinemia in the blood of infants. Thus nitrates are reduced to nitrite by the reductase enzyme, both inside and outside the human body; the formed nitrite binds with hemoglobin to form methemoglobinemia (MetHb), which cannot transport oxygen to various body tissues as a result of the oxidation of iron (Fe +2 to Fe +3 ), Fig. 5. This creates a health problem known as a blue baby syndrome. Children over three months old are more likely to have this disease, as they get large amounts of nitrates by consuming drinking water through artificial feeding; the effect of nitrates on this group of children appears more than on adults because of low concentrations of nitrates cause them disease. The study showed that all water samples from wells for ages under six years are not suitable for drinking due to exceeding the HQ value of one, which ranged between (1.0910 - 2.0939). The HQ value of more than one exceeded 80%. For ages between 6-11 years, it ranged between (0.6894 - 1.3242), which poses a threat to health safety, whereas, for ages above 11 years, the HQ value was less than one and varied between (0.5026 - 1.0145) and thus be suitable for drinking, shown in Table 3 [28-32]. Figure 5. Hemoglobi n converts to Methemoglobi nemi a i n the blood Pak. J. Anal. Environ. Che m. Vol. 23, No. 2 (2022) 284 Table 3. CDI and HQ val ues for well water. Age Groups Wells < 1.0 6 - 11 11-16 16-18 18-21 21 -65 > 65 CDI 2.8976 1.8326 1.3359 1.0919 1.4039 1.3525 1.3882 1 HQ 1.8110 1.1454 0.8349 0.6825 0.8775 0.8453 0.8676 CDI 1.7442 1.1031 0.8041 0.6573 0.8451 0.8141 0.8356 2 HQ 1.0901 0.6894 0.5026 0.4108 0.5282 0.5088 0.5223 CDI 2.9271 1.8512 1.3495 1.1031 1.4182 1.3663 1.4023 3 HQ 1.8294 1.1570 0.8434 0.6894 0.8864 0.8539 0.8765 CDI 2.6650 1.6854 1.2286 1.0043 1.2912 1.2439 1.2767 4 HQ 1.6656 1.0534 0.7679 0.6277 0.8070 0.7774 0.7980 CDI 2.9541 1.8683 1.3619 1.1132 1.4313 1.3788 1.4153 5 HQ 1.8463 1.1677 0.8512 0.6958 0.8945 0.8618 0.8845 CDI 2.9492 1.8652 1.3597 1.1114 1.4289 1.3766 1.4129 6 HQ 1.8432 1.1657 0.8498 0.6946 0.8931 0.8604 0.8831 CDI 2.7708 1.7524 1.2774 1.0442 1.3425 1.2933 1.3275 7 HQ 1.7318 1.0952 0.7984 0.6526 0.8391 0.8083 0.8297 CDI 2.6252 1.6603 1.2103 0.9893 1.2719 1.2253 1.2577 8 HQ 1.6407 1.0377 0.7564 0.6183 0.7949 0.7658 0.7860 CDI 1.9057 1.2052 0.8786 0.7181 0.9233 0.8895 0.9130 9 HQ 1.1911 0.7533 0.5491 0.4488 0.5771 0.5559 0.5706 CDI 2.8999 1.8340 1.3370 1.0928 1.4050 1.3536 1.3893 K ak hi rt a V il la g e 10 HQ 1.8125 1.1463 0.8356 0.6830 0.8782 0.8460 0.8683 CDI 3.3210 2.1003 1.5311 1.2515 1.6091 1.5501 1.5910 11 HQ 2.0756 1.3127 0.9569 0.7822 1.0057 0.9688 0.9944 CDI 3.3289 2.1053 1.5347 1.2545 1.6129 1.5538 1.5948 12 HQ 2.0805 1.3158 0.9592 0.7840 1.0080 0.9711 0.9968 CDI 3.3056 2.0906 1.5240 1.2457 1.6016 1.5429 1.5837 13 HQ 2.0660 1.3066 0.9525 0.7786 1.0010 0.9643 0.9898 CDI 3.3243 2.1024 1.5326 1.2527 1.6107 1.5517 1.5926 14 HQ 2.0777 1.3140 0.9579 0.7830 1.0067 0.9698 0.9954 CDI 3.1653 2.0019 1.4593 1.1928 1.5336 1.4774 1.5165 15 HQ 1.9783 1.2512 0.9121 0.7455 0.9585 0.9234 0.9478 CDI 3.0881 1.9530 1.4237 1.1637 1.4962 1.4414 1.4794 16 HQ 1.9300 1.2206 0.8898 0.7273 0.9351 0.9009 0.9247 CDI 3.2099 2.0301 1.4799 1.2096 1.5552 1.4983 1.5378 17 HQ 2.0062 1.2688 0.9249 0.7560 0.9720 0.9364 0.9611 CDI 3.2156 2.0337 1.4825 1.2118 1.5580 1.5009 1.5405 18 HQ 2.0097 1.2710 0.9266 0.7573 0.9737 0.9381 0.9628 CDI 3.2992 2.0866 1.5210 1.2433 1.5985 1.5399 1.5806 19 HQ 2.0620 1.3041 0.9507 0.7770 0.9991 0.9625 0.9879 CDI 3.3030 2.0889 1.5228 1.2447 1.6003 1.5417 1.5824 E in A l- H us sa n V il la ge 20 HQ 2.0643 1.3056 0.9517 0.7779 1.0002 0.9636 0.9890 CDI 3.1908 2.0180 1.4711 1.2024 1.5460 1.4894 1.528721 HQ 1.9943 1.2613 0.9194 0.7515 0.9662 0.9309 0.9554 CDI 3.2202 2.0366 1.4846 1.2135 1.5602 1.5030 1.5427 22 HQ 2.0126 1.2729 0.9279 0.7584 0.9751 0.9394 0.9642 CDI 3.3331 2.1080 1.5367 1.2560 1.6149 1.5557 1.5968 23 HQ 2.0832 1.3175 0.9604 0.7850 1.0093 0.9723 0.9980 CDI 3.3179 2.0984 1.5297 1.2503 1.6076 1.5487 1.5896 24 HQ 2.0737 1.3115 0.9560 0.7815 1.0047 0.9679 0.9935 CDI 3.3133 2.0955 1.5275 1.2486 1.6053 1.5465 1.5873 25 HQ 2.0708 1.3097 0.9547 0.7804 1.0033 0.9666 0.9921 CDI 3.3152 2.0967 1.5284 1.2493 1.6063 1.5465 1.5883 26 HQ 2.0720 1.3104 0.9553 0.7808 1.0039 0.9666 0.9927 CDI 3.3502 2.1188 1.5445 1.2625 1.6232 1.5637 1.6050 27 HQ 2.0939 1.3242 0.9653 0.7891 1.0145 0.9773 1.0031 CDI 3.3265 2.1038 1.5336 1.2536 1.6117 1.5527 1.5937 28 HQ 2.0790 1.3149 0.9585 0.7835 1.0073 0.9704 0.9960 CDI 3.3174 2.0981 1.5294 1.2501 1.6073 1.5484 1.5893 29 HQ 2.0734 1.3113 0.9559 0.7813 1.0046 0.9678 0.9933 CDI 3.1991 2.0233 1.4749 1.2056 1.5500 1.4932 1.5327 S h o u ei ra V il la g e 30 HQ 1.9995 1.2646 0.9218 0.7535 0.9688 0.9333 0.9579 Pak. J. Anal. Environ. Che m. Vol. 23, No. 2 (2022)285 Finally, the use of chemical fertilizers is increasing, resulting from the increase in the proportion of nitrogen and the lack of vegetation during the winter to the disruption of the nitrogen cycle. This led to groundwater supplies with high concentrations of nitrates, which slowly seep nitrates into the soil at a rate of 1 meter annually until it reaches the underground water level. However, a large amount of nitrogen enters groundwater through surface runoff and seepage every year [33, 34]. Good agricultural practices should be encouraged to avoid excessive nitrogenous fertilizers. Large quantities of nitrogen fertilizers will increase nitrate concentrations in groundwater by losing a large proportion of the fertilizer used by leaching into the soil [35, 36]. Conclusion Nitrate concentrations for all well water in the study area were within the permissible limits, less than 50 mgL -1 according to WHO standards. The study relied on the nitrate ion model, which requires age groups, body weight, exposure rate, and human consumption of drinking water containing nitrate concentrations. The study showed that the main HQ values were inappropriate for ages under 11 years and therefore posed a health risk to children, while older ages were good and safe to drink and did not pose a health risk in cancerous diseases. It also showed that the main reason for the high concentration of nitrates in groundwater is farmers' excessive use of nitrogen fertilizers, animal waste, and wastewater. We must try to keep the current nitrate levels from rising. By reducing agricultural fertilizers, future generations will pay the price for the current bad practices in agriculture. International water quality guidelines allow a maximum of 25 mgL -1 for infants and pregnant women and 50 mgL -1 for adults. 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