Distribution and Geochemical Controls of Arsenic and Uranium in Groundwater-Derived Drinking Water in Bihar, India

Abstract

Chronic exposure to groundwater containing elevated concentrations of geogenic contaminants such as arsenic (As) and uranium (U) can lead to detrimental health impacts. In this study, we have undertaken a groundwater survey of representative sites across all districts of the State of Bihar, in the Middle Gangetic Plain of north-eastern India. The aim is to characterize the inorganic major and trace element aqueous geochemistry in groundwater sources widely used for drinking in Bihar, with a particular focus on the spatial distribution and associated geochemical controls on groundwater As and U. Concentrations of As and U are highly heterogeneous across Bihar, exceeding (provisional) guideline values in~16% and 7% of samples (n = 273), respectively. The strongly inverse correlation between As and U is consistent with the contrasting redox controls on As and U mobility. High As is associated with Fe, Mn, lower Eh and is depth-dependent; in contrast, high U is associated with HCO 3 − , NO 3 − and higher Eh. The improved understanding of the distribution and geochemical controls on As and U in Bihar has important implications on remediation priorities and selection, and may contribute to informing further monitoring and/or representative characterization efforts in Bihar and elsewhere in India.Vaishali, noting importantly that only sources within 10 km of the Ganga River were sampled) [77]. Most recently, it has been reported that 22 districts of Bihar are currently As-impacted, although no further details such as location, non-summarized data or the functional definition of "As-impacted" are included [78]. Further, wheat consumption has recently been identified as an emerging route of As exposure in Bihar [84]. Although thorough reviews of the status of As in the Gangetic Basin are published elsewhere [78,85], the estimated population at risk for As contamination in West Bengal is 26 million people, followed by Bihar (9 million), Uttar Pradesh (3 million), Assam (1.2 million), Manipur (1 million) and Jharkhand (0.4 million) [85]. Widespread in nature, U is a radionuclide which geogenically occurs in granite and other rock types. U in groundwater can occur due to natural mobilization processes under oxic conditions, and can also be associated with anthropogenic activities such as mining, coal and fuel combustion, emissions from the nuclear industry and the use of PO 4 -based fertilizers containing U [4]. As chronic exposure to U may lead to numerous adverse health impacts including bone toxicity and impaired renal function [86,87], WHO has set a provisional guideline value of 0.13 µM (30 µg.L −1 ), noting that Germany adopted a lower threshold of 0.04 µM (10 µg.L −1 ) in 2011 [88]. Elevated concentrations of U in groundwater have been identified across the globe, including in North America (e.g., Canada [89], the United States [90,91]), Europe (e.g., Finland [87], Sweden [92], Switzerland [93], the United Kingdom [94]) and Asia (e.g., Bangladesh [95], China [96,97], Korea [98], Mongolia [99], Pakistan [43] and in the...

Characterising groundwater-surface water connectivity in the lower Gandak catchment, a barrage regulated biodiversity hotspot in the mid-Gangetic basin

“…However, the prevailing oxic and alkaline conditions and carbonate complexation with U (VI) in the lower catchment zone can facilitate U mobilisation (Barnett et al, 2002;, and results in significantly higher U concentrations in the lower catchment compared to the other two catchment zones. These concentrations are comparable with concentrations found by Richards et al (2020), but are not as high as those detected by Lapworth et al (2017) and Coyte et al (2019) in north-west India, but aquifer redox conditions are comparable and concentrations are approaching the WHO guideline value of 30 g/L.…”

“…These exceedances were only found in the upper and mid catchment, and are linked to reducing conditions in the shallow aquifer, which facilitate the reductive dissolution of iron oxyhydroxides and the release of bound arsenic (e.g. Nickson et al, 2000;BGS/DHPE 2001;Richards et al, 2020). Shallow DOC concentrations were comparable for all three catchment zones (range 0.5-2.5 mg/L), but lower concentrations (c.0.5 mg/L) are found at depth in the Pleistocene deposits across the catchment.…”

Hydrochemical characteristics and distribution of uranium in groundwater of the Geum River Basin, South Korea

“…It has been reported that the U content is high in metamorphic rocks of granite origin, acidic igneous rocks, shale, and carbonate minerals [10]. The high U concentration is associated with HCO 3 − , NO 3 − , and oxic conditions rather than acidic or anoxic conditions [11]. The major species under oxidation conditions in groundwater is U(VI) in the UO 2 2+ form, which makes neutral complexes with high mobility.…”

“…U(IV) and U(V) predominate in anaerobic conditions. U(IV) has a strong precipitation trend similar to uraninite, but the U(V) species form soluble complexes [7][8][9][10][11].…”

Arsenic Induced Breast Cancer Risk in Population of Bihar, India

“…[10][11][12][13] In the recent times, due to geogenic cause, the arsenic poisoning in ground water has increased many folds in the state of Bihar in endemic proportions. [14][15][16][17][18] This has increased the disease burden in the arsenic exposed population of Bihar. Arsenic poisoning leading to cancer has been studied globally, and a relationship between arsenic and cancer has been established.…”