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Influence of traditional agricultural practices on mobilization of arsenic from sediments to groundwater in Bengal delta

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Title Influence of traditional agricultural practices on mobilization of arsenic from sediments to groundwater in Bengal delta
 
Creator FAROOQ, SH
CHANDRASEKHARAM, D
BERNER, Z
NORRA, S
STUBEN, D
 
Subject dissolved organic-matter
irrigated rice fields
west-bengal
sequential extraction
temporal variability
spatial-distribution
drinking-water
public-health
bangladesh
contamination
arsenic contamination
dissolved organic carbon (doc)
arsenic mobilization
bengal delta
 
Description In the wake of the idea that surface derived dissolved organic carbon (DOC) plays an important role in the mobilization of arsenic (As) from sediments to groundwater and may provide a vital tool in understanding the mechanism of As contamination (mobilization/fixation) in Bengal delta; a study has been carried out. Agricultural fields that mainly cultivate rice (paddy fields) leave significantly large quantities of organic matter/organic carbon on the surface of Bengal delta which during monsoon starts decomposing and produces DOC. The DOC thus produced percolates down with rain water and mobilizes As from the sediments. Investigations on sediment samples collected from a paddy field clearly indicate that As coming on to the surface along with the irrigation water accumulates itself in the top few meters of sediment profile. The column experiments carried out on a 9 m deep sediment profile demonstrates that DOC has a strong potential to mobilize As from the paddy fields and the water recharging the aquifer through such agricultural fields contain As well above the WHO limit thus contaminating the shallow groundwater. Experiment also demonstrates that decay of organic matter induces reducing condition in the sediments. Progressively increasing reducing conditions not only prevent the adsorption of As on mineral surfaces but also cause mobilization of previously sorbed arsenic. There seems to be a cyclic pattern where As from deeper levels comes to the surface with irrigational water, accumulates itself in the sediments, and ultimately moves down to the shallow groundwater. The extensive and continual exploitation of intermediate/deep groundwater accelerates this cyclic process and helps in the movement of shallow contaminated groundwater to the deeper levels.
 
Publisher PERGAMON-ELSEVIER SCIENCE LTD
 
Date 2011-08-25T08:27:46Z
2011-12-26T12:56:59Z
2011-12-27T05:46:39Z
2011-08-25T08:27:46Z
2011-12-26T12:56:59Z
2011-12-27T05:46:39Z
2010
 
Type Article
 
Identifier WATER RESEARCH, 44(19), 5575-5588
0043-1354
http://dx.doi.org/10.1016/j.watres.2010.05.057
http://dspace.library.iitb.ac.in/xmlui/handle/10054/10954
http://hdl.handle.net/10054/10954
 
Language en