- The London Arsenic Group, in collaboration with the University of
Delhi and IIT Kharagpur, makes available its latest research in the
journal "Water Resources Research".
How paleosols influence groundwater flow and arsenic pollution: a
model from the Bengal Basin and its worldwide implication.
J.M. McArthur, P. Ravenscroft, D.M. Banerjee, J. Milsom, K.A.
Hudson-Edwards, S. Sengupta, C. Bristow, A. Sarkar, S. Tonkin, R. Purohit.
Water Resour. Res., 44, W11411, doi:10.1029/2007WR006552.
Abstract. In the Bengal Basin, the land surface exposed during the
last lowstand of sea-level around 20 ka, and now buried by Holocene
sediment, is capped by an impermeable clay palaeosol that we term the
Last Glacial Maximum Palaeosol (LGMP). The palaeosol strongly affects
groundwater flow and controls the location of arsenic pollution in
the shallow aquifers of our study site in southern West Bengal and,
by implication, in shallow aquifers across the Bengal Basin and
As-polluted deltaic aquifers worldwide. The presence of the LGMP
defines palaeo-interfluvial areas; it is absent from palaeo-channel
areas. A palaeosol model of pollution proposed here predicts that
groundwater in palaeo-channels is polluted by arsenic, whilst that
beneath palaeo-interfluvial areas is not: palaeo-interfluvial
aquifers are unpolluted because they are protected by the LGMP from
downward migration of arsenic, and from downward migration of organic
matter that drives As-pollution via reductive-dissolution of
As-bearing iron oxyhydroxides. Horizontal groundwater flow carries
arsenic from palaeo-channels towards palaeo-interfluvial aquifers, in
which sorption of arsenic minimizes the risk of pollution.
Professor of Geochemistry
University College London
London WC1E 6BT
phone +44 (0)20 7679 2376
Fax +44 (0)20 7679 4166
London Arsenic Group