Nuclear Chemistry and Environmental Research Centre, National Nuclear Research Institute, Ghana Atomic Energy Commission, Box LG 80, Legon-Accra, Ghana.
Graduate School of Nuclear and Allied Sciences, Box AE 1, Atomic Energy Commission, Accra, Ghana.
J Contam Hydrol. 2020 Aug;233:103658. doi: 10.1016/j.jconhyd.2020.103658. Epub 2020 May 24.
The rising food production to meet the growing human population has led to increased anthropogenic inputs of nutrients such as NO in groundwater and aquatic environments. Nitrate concentrations, hydrochemistry, and isotope data (δO-HO, δH-HO, N-NO, and δO-NO) from boreholes (BH), hand dug wells (HDW), and surface water (SW) were analyzed. The objectives of the study were to identify potential nitrate sources and their proportional contributions using an isotope mixing model (SIAR). The results showed that NO concentrations in the BH, HDW, and SW were heterogeneous and controlled by localized anthropogenic activities. The hydrochemistry and dual isotope (N-NO and O-NO) identified manure/sewage as the dominant source of NO in the groundwater, while the SW showed a complex signature overlapping in the areas of manure/septic, chemical fertilizer, and soil nitrogen. The SIAR analysis showed that sewage/manure contributed about 66%, 68%, and 55% of NO in the BH, HDW, and SW, respectively. In the study area, the NO source contribution based on the mean probable estimate (MPE) were in the order S&M > SN > CF > P. Shortcomings and the uncertainties associated with the SIAR to guide future studies have also been discussed. The study also highlighted the use of hydrochemistry, environmental isotopes, and Bayesian isotope mixing models for NO source identification and apportionment. This is to enable effective planning, farming practices, and sewage disposals to safeguard groundwater quality and control the eutrophication in rivers to meet safe drinking water demand.
为了满足不断增长的人口对粮食的需求，人类活动向地下水和水生环境中输入了大量营养物质，如硝酸盐。本研究分析了钻孔（BH）、手挖井（HDW）和地表水（SW）中的硝酸盐浓度、水化学和同位素数据（δO-HO、δH-HO、N-NO 和 δO-NO）。本研究的目的是利用同位素混合模型（SIAR）确定潜在的硝酸盐来源及其比例贡献。结果表明，BH、HDW 和 SW 中的硝酸盐浓度不均匀，受局部人为活动控制。水化学和双同位素（N-NO 和 O-NO）确定了粪肥/污水是地下水硝酸盐的主要来源，而 SW 则显示出一个复杂的特征，在粪肥/污水、化肥和土壤氮等地区重叠。SIAR 分析表明，污水/粪肥分别为 BH、HDW 和 SW 中的硝酸盐贡献了约 66%、68%和 55%。在研究区域中，基于平均可能估计（MPE）的硝酸盐源贡献顺序为 S&M > SN > CF > P。还讨论了 SIAR 在指导未来研究方面的局限性和不确定性。该研究还强调了水化学、环境同位素和贝叶斯同位素混合模型在硝酸盐源识别和分配中的应用。这是为了实现有效的规划、农业实践和污水处理，以保护地下水质和控制河流富营养化，以满足安全饮用水需求。
