Hydrological control of As concentrations in Bangladesh groundwater

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Read Full Article (file size: 1845577 bytes) Cited by WATER RESOURCES RESEARCH, VOL. 43, W09417, doi:10.1029/2005WR004499, 2007 Hydrological control of As concentrations in Bangladesh groundwater M. Stute Department of Environmental Science, Barnard College, New York, New York, USA Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, USA Y. Zheng Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, USA School of Earth and Environmental Science, Queens College, City University of New York, Flushing, New York, USA P. Schlosser Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, USA Departments of Earth and Environmental Engineering and Earth and Environmental Sciences, Columbia University, New York, New York, USA A. Horneman Departments of Earth and Environmental Engineering and Earth and Environmental Sciences, Columbia University, New York, New York, USA R. K. Dhar School of Earth and Environmental Science, Queens College, City University of New York, Flushing, New York, USA S. Datta Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, USA M. A. Hoque Department of Geology, University of Dhaka, Dhaka, Bangladesh A. A. Seddique Department of Geology, University of Dhaka, Dhaka, Bangladesh M. Shamsudduha Department of Geology, University of Dhaka, Dhaka, Bangladesh K. M. Ahmed Department of Geology, University of Dhaka, Dhaka, Bangladesh A. van Geen Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, USA Abstract The elevated arsenic (As) content of groundwater from wells across Bangladesh and several other South Asian countries is estimated to slowly poison at least 100 million people. The heterogeneous distribution of dissolved arsenic in the subsurface complicates understanding of its release from the sediment matrix into the groundwater, as well as the design of mitigation strategies. Using the tritium-helium (³H/³He) groundwater dating technique, we show that there is a linear correlation between groundwater age at depths <20 m and dissolved As concentration, with an average slope of 19 μg L⁻¹ yr⁻¹ (monitoring wells only). We propose that either the kinetics of As mobilization or the removal of As by groundwater flushing is the mechanism underlying this relationship. In either case, the spatial variability of As concentrations in the top 20 m of the shallow aquifers can to a large extent be attributed to groundwater age controlled by the hydrogeological heterogeneity in the local groundwater flow system. Received 11 August 2005; accepted 24 May 2007; published 26 September 2007. Keywords: arsenic; Bangladesh; tritium; helium; groundwater; reaction kinetics. Index Terms: 1832 Hydrology: Groundwater transport; 1834 Hydrology: Human impacts; 1880 Hydrology: Water management (6334). Read Full Article (file size: 1845577 bytes) Cited by Citation: Stute, M., et al. (2007), Hydrological control of As concentrations in Bangladesh groundwater, Water Resour. Res., 43, W09417, doi:10.1029/2005WR004499. Copyright 2007 by the American Geophysical Union.

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