Migration of As, and 3H/3He ages, in groundwater from West Bengal: Implications for monitoring

McArthur, J. M.; Banerjee, D. M.; Sengupta, S.; Ravenscroft, Peter; Klump, Stephan; Sarkar, Anindya; Disch, Benoit A.; Kipfer, Rolf

doi:10.1016/j.watres.2010.05.010

Cited by 87 publications

(63 citation statements)

References 27 publications

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“…The difference represents wells at the margins of palaeo-interfluves where local migration of As-polluted waters has brought As to marginal PI settings and is now polluting wells that previously were low in As, as has been documented elsewhere (McArthur et al 2010).…”

Section: Water Compositionmentioning

confidence: 78%

“…Push-pull, in situ, experiments in Bangladesh gave a value of 13 L/kg (Radloff et al 2011). Assuming K d value of 13 L/kg, a retardation factor 70 can be estimated for the brown sand of the Bengal Basin (taking 30 % porosity, 1.6 g/cm 3 bulk density), and this value is in the range of field-based estimates of a factor of>30 by McArthur et al (2010). Using this value in the OgataBanks solution (Ogata and Banks 1961), a well that is protected by a 50 m thickness of brown sand (e.g.…”

Section: Mitigationmentioning

confidence: 94%

“…Stollenwerk et al 2007). At such contacts, the concentrations of As in PI groundwaters are locally >5 μg/L because the sorption capacity of the brown sands is overwhelmed by As in the invading groundwater (McArthur et al 2010). …”

Section: Study Area and Its Sedimentological Developmentmentioning

confidence: 99%

“…Changes can be marked over a period as little as 2 years (McArthur et al 2010). LowAs wells become As-polluted and black well-stain becomes overprinted by red stain, making colour differentiation difficult.…”

Section: Mitigationmentioning

confidence: 99%

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Sources of low-arsenic groundwater in the Bengal Basin: investigating the influence of the last glacial maximum palaeosol using a 115-km traverse across Bangladesh

2014

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Pollution of groundwater in the Bengal Basin (Bangladesh and West Bengal, India) by arsenic (As) puts at risk the health of more than 100 million consumers. Using 1,580 borehole lithological logs and published hydrochemistry on 2,387 wells, it was predicted that lowAs (<10 μg/L) groundwater exists, in palaeo-interfluvial aquifers of brown sand capped by a protective palaeosol, beneath at least 45,000 km 2 of the Bengal Basin. The aquifers were predicted to be at a depth of as little as 25 m below ground level (mbgl), and typically no more than 50 mbgl. The predictions were confirmed along an eastwest traverse 115 km in length (i.e. across half of Bangladesh) by drilling 28 new boreholes to 91-m depth to reveal subsurface sedimentology, and by mapping As distribution in groundwater. The aquifers identified occur at typically <40 mbgl and so are accessible with local drilling methods. A protective palaeosol that caps the palaeo-interfluvial aquifers prevents downward movement into them of As-polluted groundwater present in shallower palaeo-channel aquifers and ensures that the palaeointerfluvial aquifers will yield low-As groundwater for the foreseeable future. Their use, in place of the shallower As-polluted palaeo-channel aquifers, would rapidly mitigate the health risks from consumption of As-polluted groundwater.

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Section: Water Compositionmentioning

confidence: 78%

Section: Mitigationmentioning

confidence: 94%

Section: Study Area and Its Sedimentological Developmentmentioning

confidence: 99%

Section: Mitigationmentioning

confidence: 99%

See 2 more Smart Citations

Sources of low-arsenic groundwater in the Bengal Basin: investigating the influence of the last glacial maximum palaeosol using a 115-km traverse across Bangladesh

2014

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“…Buried natural organic matter or peat is implicated as the fuel for reductive dissolution of arsenic-bearing iron (hydr)oxides, leading to As release in the Bengal Basin (McArthur et al, 2004;McArthur et al, 2010;McArthur et al, 2011;McArthur et al, 2008;McArthur et al, 2001). Peat may potentially drive arsenic release locally and/or produce dissolved organic carbon (DOC), which may stimulate As release down gradient in the aquifer (McArthur et al, 2008).…”

Section: Peat Formation Concentrates Arsenic Within Sediment Depositsmentioning

confidence: 99%

Peat formation concentrates arsenic within sediment deposits of the Mekong Delta

Stuckey

Schaefer

Kocar

et al. 2015

Geochimica et Cosmochimica Acta

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This is an author-produced, peer-reviewed version of this article. The final, definitive version of this document can be found online at Geochimica et Cosmochimica Acta, published by Elsevier. Copyright restrictions may apply. doi: 10.1016/j.gca.2014.10.021 Mekong River Delta sediment bears arsenic that is released to groundwater under anaerobic conditions over the past several thousand years. The oxidation state, speciation, and distribution of arsenic and the associated iron bearing phases are crucial determinants of As reactivity in sediments. Peat from buried mangrove swamps in particular may be an important host, source, or sink of arsenic in the Mekong Delta. The total concentration, speciation, and reactivity of arsenic and iron were examined in sediments in a Mekong Delta wetland by X-ray fluorescence spectrometry (XRF), X-ray absorption spectroscopy (XA S), and selective chemical extractions. Total solid-phase arsenic concentrations in a peat layer at a depth of 6 m below ground increased 10-fold relative to the overlying sediment. Extended X-ray absorption fine structure (EXAFS) spectroscopy revealed that arsenic in the peat was predominantly in the form of arsenian pyrite. Arsenic speciation in the peat was examined further at the micron-scale using XRF and X-ray absorption near-edge structure (XANES) spectroscopy coupled with principal component analysis. The multiple energy XRF mapping and XANES routine was repeated for both iron and sulfur phase analyses. Our XRF/ XANES analyses confirm arsenic association with pyrite -a less reactive host phase than iron (hydr)oxides under anaerobic conditions. The arsenian pyrite likely formed upon deposition/formation of the peat in a past estuarine environment (~ 5.5 ka BP), a process that is not expected under current geochemical conditions. Presently, arsenian pyrite is neither a source nor a sink for aqueous arsenic in our sediment profile, and under present geochemical conditions represents a stable host of As under the reducing aquifer conditions of the Mekong Delta. AbstractThis is an author-produced, peer-reviewed version of this article. The final, definitive version of this document can be found online at Geochimica et Cosmochimica Acta, published by Elsevier.

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A generalized regression model of arsenic variations in the shallow groundwater of Bangladesh

2015

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Localized studies of arsenic (As) in Bangladesh have reached disparate conclusions regarding the impact of irrigation‐induced recharge on As concentrations in shallow (≤50 m below ground level) groundwater. We construct generalized regression models (GRMs) to describe observed spatial variations in As concentrations in shallow groundwater both (i) nationally, and (ii) regionally within Holocene deposits where As concentrations in groundwater are generally high (>10 μg L−1). At these scales, the GRMs reveal statistically significant inverse associations between observed As concentrations and two covariates: (1) hydraulic conductivity of the shallow aquifer and (2) net increase in mean recharge between predeveloped and developed groundwater‐fed irrigation periods. Further, the GRMs show that the spatial variation of groundwater As concentrations is well explained by not only surface geology but also statistical interactions (i.e., combined effects) between surface geology and mean groundwater recharge, thickness of surficial silt and clay, and well depth. Net increases in recharge result from intensive groundwater abstraction for irrigation, which induces additional recharge where it is enabled by a permeable surface geology. Collectively, these statistical associations indicate that irrigation‐induced recharge serves to flush mobile As from shallow groundwater.

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Migration of As, and 3H/3He ages, in groundwater from West Bengal: Implications for monitoring

Cited by 87 publications

References 27 publications

Sources of low-arsenic groundwater in the Bengal Basin: investigating the influence of the last glacial maximum palaeosol using a 115-km traverse across Bangladesh

Sources of low-arsenic groundwater in the Bengal Basin: investigating the influence of the last glacial maximum palaeosol using a 115-km traverse across Bangladesh

Peat formation concentrates arsenic within sediment deposits of the Mekong Delta

A generalized regression model of arsenic variations in the shallow groundwater of Bangladesh

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