Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, Durham, NC 27708, USA.
Department of Geology, Mohanlal Sukhadia University, Udaipur, Rajasthan 313001, India.
Sci Total Environ. 2019 Oct 20;688:1216-1227. doi: 10.1016/j.scitotenv.2019.06.334. Epub 2019 Jun 23.
Northwest India suffers from severe water scarcity issues due to a combination of over-exploitation and climate effects. Along with concerns over water availability, endemic water quality issues are critical and affect the usability of available water and potential human health risks. Here we present data from 243 groundwater wells, representing nine aquifer lithologies in 4 climate regions that were collected from the Northwestern Indian state of Rajasthan. Rajasthan is India's largest state by area, and has a significant groundwater reliant population due to a general lack of surface water accessibility. We show that the groundwater, including water that is used for drinking without any treatment, contains multiple inorganic contaminants in levels that exceed both Indian and World Health Organization (WHO) drinking water guidelines. The most egregious of these violations were for fluoride, nitrate, and uranium; 76% of all water samples in this study had contaminants levels that exceed the WHO guidelines for at least one of these species. In addition, we show that much of the groundwater contains high concentrations of dissolved organic carbon (DOC) and halides, both of which are risk factors for the formation of disinfectant byproducts in waters that are treated with chemical disinfectants such as chlorine. By using geochemical and isotopic (oxygen, hydrogen, carbon, strontium, and boron isotopes) data, we show that the water quality issues derive from both geogenic (evapotranspiration, water-rock interactions) and anthropogenic (agriculture, domestic sewage) sources, though in some cases anthropogenic activities, such as infiltration of organic- and nitrate-rich water, may contribute to the persistence and enhanced mobilization of geogenic contaminants. The processes affecting Rajasthan's groundwater quality are common in many other worldwide arid areas, and the lessons learned from evaluation of the mechanisms that affect the groundwater quality are universal and should be applied for other parts of the world.
由于过度开采和气候影响，印度西北部面临严重的水资源短缺问题。除了对水资源供应的担忧外，地方性的水质问题也很关键，影响着可用水资源的可用性和潜在的人类健康风险。在这里，我们展示了来自印度拉贾斯坦邦西北部的 243 口地下水井的数据，这些水井代表了四个气候区的 9 种含水层岩性。拉贾斯坦邦是印度面积最大的邦，由于地表水普遍难以获取，因此依赖地下水的人口众多。我们表明，包括未经任何处理就用于饮用的地下水在内，都含有多种无机污染物，其浓度超过了印度和世界卫生组织（WHO）的饮用水标准。这些违规行为中最严重的是氟化物、硝酸盐和铀；在本研究的所有水样中，有 76%的水样至少有一种污染物浓度超过了 WHO 的标准。此外，我们还表明，大部分地下水都含有高浓度的溶解有机碳（DOC）和卤化物，这两者都是在使用化学消毒剂（如氯）处理水时形成消毒剂副产物的风险因素。通过使用地球化学和同位素（氧、氢、碳、锶和硼同位素）数据，我们表明，水质问题既源自地球成因（蒸发蒸腾、水-岩相互作用），也源自人为成因（农业、生活污水），尽管在某些情况下，人为活动（如富含有机物和硝酸盐的水的渗透）可能会导致地球成因污染物的持续存在和更易迁移。影响拉贾斯坦邦地下水质量的过程在世界上许多其他干旱地区都很常见，从评估影响地下水质量的机制中获得的经验教训是普遍适用的，应该应用于世界其他地区。
