Department of Civil Engineering, Kwame Nkrumah University of Science and Technology (KNUST), Private Mail Bag, University Post Office, Kumasi, Ghana.
Department of Civil Engineering, Kwame Nkrumah University of Science and Technology (KNUST), Private Mail Bag, University Post Office, Kumasi, Ghana; Nuclear Chemistry and Environmental Research Center, National Nuclear Research Institute, GAEC, Box LG 80, Legon, Accra, Ghana.
Sci Total Environ. 2017 Dec 15;603-604:687-698. doi: 10.1016/j.scitotenv.2017.01.219. Epub 2017 Apr 21.
In this study, we present a first attempt on the use of integrated hydro-chemical and isotopic technique to trace the sources of groundwater nitrate contamination in the Upper East Region of Ghana to aid the sustainable management of this vital resource. The objectives of the study are (1) assess the present status and spatial distribution of the nitrate contamination (2) identify and distinguish the most likely sources of nitrate , (3) identify the relationship between H and NO and F, and (4) ascertain the potential human risk from exposure to nitrate contamination. The results showed that, nitrate concentrations varied from 0.42 to 431.17, 0.83 to 143.94, 0.03 to 28.94mg/l with mean values of 36.09, 21.54 and 5.01mg/l for boreholes, hand dug wells and the surface water respectively. These values showed that, about 95% of boreholes and hand dug wells and 45% of the surface water have nitrate concentration above the baseline value in the area. The NO/Cl ratio showed that, 98.4%, 95% and 64% of the NO in the borehole, hand dug wells and the surface water are from anthropogenic activities. The δNNO and δONO data confirmed that NO in the samples was predominantly derived from manure (human and animal waste) and denitrification occurring in some areas. The isotopic data further affirms the hydro-chemical interpretation that, chemical fertilizer and atmospheric deposition are unlikely sources of NO in the area. The relationship between H and NO concentrations showed that, higher NO values are associated with younger waters. Non carcinogenic health risk for adults and children posed by oral ingestion of the NO contaminated water revealed some degree of health risk, especially to children whose risk is about 72% higher. The study provides a conceptual model of the NO dynamics and some recommendation for groundwater management in the area.
在这项研究中，我们首次尝试将水化学和同位素技术综合应用于追踪加纳上东部地区地下水硝酸盐污染的来源，以帮助可持续管理这一重要资源。本研究的目的是：(1)评估硝酸盐污染的现状和空间分布；(2)识别和区分硝酸盐的最可能来源；(3)确定 H 和 NO 与 F 之间的关系；(4)确定接触硝酸盐污染的潜在人体风险。结果表明，钻孔、手挖井和地表水的硝酸盐浓度分别在 0.42 至 431.17mg/L、0.83 至 143.94mg/L 和 0.03 至 28.94mg/L 之间变化，平均值分别为 36.09mg/L、21.54mg/L 和 5.01mg/L。这些值表明，约 95%的钻孔和手挖井以及 45%的地表水的硝酸盐浓度高于该地区的基线值。NO/Cl 比值表明，钻孔、手挖井和地表水 98.4%、95%和 64%的 NO 来自人为活动。δNNO 和 δONO 数据证实，样品中的 NO 主要来自粪肥（人和动物废物）和一些地区的反硝化作用。同位素数据进一步证实了水化学解释，即化肥和大气沉降不太可能是该地区 NO 的来源。H 和 NO 浓度之间的关系表明，NO 值越高，与之相关的水龄越年轻。通过口服摄入受 NO 污染的水对成人和儿童造成的非致癌健康风险显示出一定程度的健康风险，尤其是儿童，其风险高出约 72%。该研究提供了一个关于 NO 动态的概念模型，并为该地区的地下水管理提出了一些建议。
