Flushing History as a Hydrogeological Control on the Regional Distribution of Arsenic in Shallow Groundwater of the Bengal Basin

Whereas serious health consequences of widespread consumption of groundwater elevated in As have been documented in several South Asian countries, the mechanisms responsible for As mobilization in reducing aquifers remain poorly understood. We document here a previously unrecognized and consistent r...

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Bibliographic Details
Published in:Environmental science & technology 2008-04, Vol.42 (7), p.2283-2288
Main Authors: van Geen, A, Zheng, Y, Goodbred, S, Horneman, A, Aziz, Z, Cheng, Z, Stute, M, Mailloux, B, Weinman, B, Hoque, M. A, Seddique, A. A, Hossain, M. S, Chowdhury, S. H, Ahmed, K. M
Format: Article
Language:English
Subjects:
Applied sciences
Aquifers
Arsenic
Arsenic - analysis
Asia
Characterization of Natural and Affected Environments
Environmental science
Exact sciences and technology
Geologic Sediments - chemistry
Geological Phenomena
Geology
Groundwater
Hydrology
Iron - analysis
Oxidation-Reduction
Pollution
Water Pollutants, Chemical - analysis
Water supply
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Summary:Whereas serious health consequences of widespread consumption of groundwater elevated in As have been documented in several South Asian countries, the mechanisms responsible for As mobilization in reducing aquifers remain poorly understood. We document here a previously unrecognized and consistent relationship between dissolved As concentrations in reducing groundwater and the phosphate-mobilizable As content of aquifer sediment for a set of precisely depth-matched samples from across Bangladesh. The relationship holds across nearly 3 orders of magnitude in As concentrations and suggests that regional as well as local patterns of dissolved As in shallow groundwater are set by the solid phase according to a remarkably constant ratio of ∼250 μg/L dissolved As per 1 mg/kg P-mobilizable As. We use this relationship in a simple model of groundwater recharge to propose that the distribution of groundwater As in shallow aquifers of the Bengal Basin could primarily reflect the different flushing histories of sand formations deposited in the region over the past several thousand years.
ISSN:0013-936X
1520-5851
DOI:10.1021/es702316k