A significant population within the Lower Volta River Basin of Ghana relies solely on untreated groundwater (GW) and surface water (SW) for various purposes. However, negative practices associated with increasing human activities pose threats to particularly GW quality in the basin. Using NO3- as a proxy, this study mainly focused on the status of GW contamination, origins of NO3- and potential human health risks through integrated hydrochemistry, correlation analysis, isotopes (15N, δ18O), Bayesian and USEPA human health risk models. Slightly acidic to alkaline GW and SW environments were observed. Electrical conductivity (EC) values above 1000 μS/cm were recorded in 45% of the GW with a maximum of 19370 μS/cm. NO3- in GW ranged from 0.12 to 733 mg/L with average 59.6 mg/L and positively correlated with K+, Ca2+, Mg2+, Cl-, Na+ and EC. In SW, a maximum of 5.3 mg/L of NO3- was observed. Largely, 75% of the GW exceeded local background NO3- value of 2.1 mg/L, while 35% were above the WHO recommended value of 50 mg/L. Bivariate and correlation relationships elucidated human contributions to sources of NO3-, Cl-, SO42- and K+ to GW in the basin. From NO3-/Cl- ratio, 43% of the GW and 21% of SW were affected by effluents and agrochemicals. Values for δ15N-NO3- and δ18O-NO3- ranged from +4.2‰ to +27.5‰ and +4.5‰ to +19.9‰ for GW, and from +3.8‰ to +14.0‰ and +10.7‰ to +25.2‰ for SW. Manure, septic effluents and mineralized fertilizers are sources of NO3- contamination of water in the basin. The Bayesian model apportioned 80% of GW NO3- contamination to sewage/manure. Hazard index indicated 70%, 50% and 48% medium to high-risk levels for infants, children and adults respectively, with 79% high-risk of SW NO2- contamination to infants. Immediate measures for GW and SW quality protection are recommended.

中文翻译：

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加纳下沃尔塔河流域地下水的硝酸盐污染：来源和相关的人类健康风险。

加纳下沃尔塔河流域中的大量人口仅出于各种目的而完全依赖未经处理的地下水（GW）和地表水（SW）。但是，与人类活动增加相关的负面做法对流域的GW质量尤其构成威胁。本研究以NO3-为代表，主要研究了GW污染的状况，NO3-的起源以及通过综合水化学，相关分析，同位素（15N，δ18O），贝叶斯和USEPA人类健康风险模型得出的潜在人类健康风险。观察到略微酸性至碱性的GW和SW环境。在45％的GW中记录到的电导率（EC）值超过1000μS/ cm，最大值为19370μS/ cm。GW中的NO3-在0.12至733 mg / L范围内，平均为59.6 mg / L，并且与K +，Ca2 +，Mg2 +，Cl-，Na +和EC正相关。在西南，观察到最多5.3 mg / L的NO3-。在很大程度上，有75％的GW超过了当地本底NO3-值2.1 mg / L，而35％的超出了WHO的建议值50 mg / L。双变量和相关关系阐明了人类对流域GW的NO3-，Cl-，SO42-和K +来源的贡献。从NO3- / Cl-比率来看，废水和农用化学品影响了43％的GW和21％的SW。GW的δ15N-NO3-和δ18O-NO3-的值介于+ 4.2‰至+ 27.5‰和GW的+ 4.5‰至+ 19.9‰，而SW的值介于+ 3.8‰至+ 14.0‰和+ 10.7‰至+ 25.2‰ 。粪便，化粪池污水和矿化肥料是流域水中NO3污染的来源。贝叶斯模型将80％的GW NO3-污染物分配给污水/粪便。危险指数表明婴儿，儿童和成人的中至高风险水平分别为70％，50％和48％，婴儿患SW NO2-的高风险为79％。建议立即采取措施保护GW和SW。