Protection of groundwater quality from various natural and anthropogenic forces is a prime concern in Bangladesh. In this study, we utilized groundwater geochemistry of shallow and deeper aquifers to investigate the hydrogeochemical processes controlling water quality, and the sources and mechanism of Arsenic (As) release to water and associated human health risks in the Faridpur district, Bangladesh. Analysis of hydrochemical facies indicated that groundwaters were Ca–Mg–HCO₃ type and that water–rock interactions were the dominant factors controlling their major-ion chemical composition. The dissolution of calcite, dolomite, and silicates, as well as cation exchange processes regulated the major ions chemistry in the groundwater. Dissolved fluoride (F⁻) concentrations (0.02–0.4 mg/L) were lower than the drinking water standard of 1.5 mg/L set by the World Health Organization (WHO). Arsenic contamination of groundwater is among the biggest health threats in Bangladesh. The measured As concentration (0.01–1.46 mg/L with a mean of 0.12 mg/L) exceeded the maximum permissible limit of Bangladesh and WHO for drinking water. The estimated carcinogenic risk of As exceeded the upper benchmark of 1 × 10^–4 for both adult and children, and health threats from shallow groundwater were more severe than the deeper water. The vertical distribution of As resembled Fe and Mn with their higher concentrations in shallow Holocene aquifers and lower in deeper Pleistocene aquifers. Speciation calculation indicated the majority of groundwater samples were oversaturated with respect to siderite, calcite, and dolomite, while undersaturated with respect to rhodochrosite. The saturation state of the minerals along with other processes may exert kinetic control on As, Fe, and Mn distribution in groundwater and lead to their lack of statistically significant correlations. Microbially mediated reductive dissolution of Fe and Mn oxyhydroxides is envisaged as the primary controlling mechanism of As mobilization in Faridpur groundwater. Pyrite oxidation was not postulated as a plausible explanation of As pollution.

在孟加拉国，保护地下水质量免受各种自然和人为因素的影响是首要考虑的问题。在这项研究中，我们利用浅层和深层含水层的地下水地球化学来研究控制水质的水文地球化学过程，以及孟加拉国Faridpur地区向水中释放的砷（As）的来源和机理以及相关的人类健康风险。对水化学相的分析表明，地下水为Ca–Mg–HCO ₃类型，水-岩石相互作用是控制其主要离子化学组成的主要因素。方解石，白云石和硅酸盐的溶解以及阳离子交换过程调节了地下水中主要离子的化学性质。溶解氟（F ^-）浓度（0.02–0.4 mg / L）低于世界卫生组织（WHO）设定的饮用水标准1.5 mg / L。地下水的砷污染是孟加拉国最大的健康威胁之一。所测得的砷浓度（0.01–1.46 mg / L，平均值为0.12 mg / L）超过了孟加拉国和世界卫生组织对饮用水的最大允许限值。砷的估计致癌风险超过了最高基准1×10 ^–4对成人和儿童而言，浅层地下水对健康的威胁要比深层水严重。As的垂直分布类似于Fe和Mn，在浅全新世含水层中浓度较高，而在较新世含水层中浓度较低。形态计算表明，大多数地下水样品中的菱铁矿，方解石和白云石都过饱和，而菱锰矿则过饱和。矿物的饱和状态以及其他过程可能会对地下水中的As，Fe和Mn分布施加动力学控制，并导致它们缺乏统计上显着的相关性。微生物介导的Fe和Mn羟基氧化氢氧化物的还原溶解被认为是Faridpur地下水中As迁移的主要控制机制。