Groundwater resources in the crystalline basement complex of India are crucial for supplying drinking water in both rural and urban settings. Groundwater depletion is recognised as a challenge across parts of India due to over-abstraction, but groundwater quality constraints are perhaps even more widespread and often overlooked at the local scale. Uranium contamination in basement aquifers has been reported in many parts of India, locally exceeding WHO drinking water guideline values of 30 μg/L and posing a potential health risk. In this study 130 water samples were collected across three crystalline basement catchments to assess hydrochemical, geological and anthropogenic controls on uranium mobility and occurrence in drinking water sources. Groundwaters with uranium concentrations exceeding 30 μg/L were found in all three study catchments (30% of samples overall), with concentrations up to 589 μg/L detected. There appears to be a geological control on the occurrence of uranium in groundwater with the granitic gneiss of the Halli and Bengaluru study areas having higher mean uranium concentrations (51 and 68 μg/L respectively) compared to the sheared gneiss of the Berambadi catchment (6.4 μg/L). Uranium – nitrate relationships indicate that fertiliser sources are not a major control on uranium occurrence in these case studies which including two catchments with a long legacy of intense agricultural land use. Geochemical modelling confirmed uranium speciation was dominated by uranyl carbonate species, particularly ternary complexes with calcium, consistent with uranium mobility being affected by redox controls and the presence of carbonates. Urban leakage in Bengaluru led to low pH and low bicarbonate groundwater hydrochemistry, reducing uranium mobility and altering uranium speciation. Since the majority of inhabitants in Karnataka depend on groundwater abstraction from basement aquifers for drinking water and domestic use, exposure to elevated uranium is a public health concern. Improved monitoring, understanding and treatment of high uranium drinking water sources in this region is essential to safeguard public health.

印度水晶地下室的地下水资源对于农村和城市环境中的饮用水供应至关重要。由于过度抽取，地下水枯竭被认为是印度部分地区的挑战，但地下水质量限制可能更为普遍，并且在当地范围内经常被忽视。印度许多地方都报告了地下室含水层中的铀污染，当地超过了世卫组织饮用水准则值 30 微克/升，并构成潜在的健康风险。在这项研究中，在三个结晶基底集水区收集了 130 个水样，以评估水化学、地质和人为控制对饮用水源中铀迁移和发生的控制。在所有三个研究集水区（总样本的 30%）都发现了铀浓度超过 30 微克/升的地下水，检测到的浓度高达 589 微克/升。与 Berambadi 集水区的剪切片麻岩（6.4微克/升）。铀 - 硝酸盐关系表明，在这些案例研究中，肥料来源不是对铀发生的主要控制，其中包括两个长期大量使用农业土地的集水区。地球化学模型证实铀的物种形成主要是碳酸铀酰物种，特别是与钙的三元配合物，与受氧化还原控制和碳酸盐存在影响的铀迁移率一致。班加罗尔的城市渗漏导致低 pH 值和低碳酸氢盐地下水水化学，降低了铀的流动性并改变了铀的形态。由于卡纳塔克邦的大多数居民依赖从地下室含水层抽取地下水用于饮用水和家庭用水，因此暴露于高浓度铀是一个公共卫生问题。改善对该地区高铀饮用水源的监测、了解和处理对于保障公众健康至关重要。由于卡纳塔克邦的大多数居民依赖从地下室含水层抽取地下水用于饮用水和家庭用水，因此暴露于高浓度铀是一个公共卫生问题。改善对该地区高铀饮用水源的监测、了解和处理对于保障公众健康至关重要。由于卡纳塔克邦的大多数居民依赖从地下室含水层抽取地下水用于饮用水和家庭用水，因此暴露于高浓度铀是一个公共卫生问题。改善对该地区高铀饮用水源的监测、了解和处理对于保障公众健康至关重要。