Dear Colleagues,Readers may be interested in the following publication, and the introduction to it given below.
It becomes increasingly clear that severe arsenic pollution of ground water in most alluvial aquifers worldwide is driven by the microbially-mediated metabolism of organic matter, with FeOOH acting as the source of oxygen: the oxyhydroxide is reduced during the process and its sorbed arsenic is released to ground water. Despite the widespread acceptance of this mechanism, much about it remains obscure.
In the paper available on-line from the journal 'Applied Geochemistry', the London Arsenic Group reveal more details of the process, and show why arsenic pollutes much of the shallow aquifer in West Bengal: the pollution appears to be related spacially to the distribution of organic matter in the aquifer. The authors also argue that tectonics influence arsenic pollution, and that peaky vertical profiles of arsenic pollution in ground water, seen widely across the Bengal Basin, show that abstraction of water, for domestic use and irrigation, is purging the shallow aquifer of arsenic pollution.
J.M. McArthur, D.M. Banerjee, K.A. Hudson-Edwards, R. Mishra, R. Purohit, P. Ravenscroft, A. Cronin, R.J. Howarth, A. Chatterjee, T. Talukder, D. Lowry, S. Houghton, and D.K. Chadha. Natural organic matter in sedimentary basins and its relation to arsenic in anoxic ground water: the example of West Bengal and its worldwide implications. Applied Geochemistry, 19(8), 1255-1293 (2004).
Sincerely,
John McArthur
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