HR: 15:25h
AN: H13L-08 [Abstracts]
TI: Hydrogeochemistry and adsorption behaviour of As-enriched sediment from Bengal Delta Plain, India
AU: * Nath, B
EM: bibhash12@yahoo.com
AF: Department of Earth Sciences, National Cheng Kung University
1 University Road, Tainan, 70101, Taiwan
AU: * Nath, B
EM: bibhash12@yahoo.com
AF: Department of Chemistry, University of Kalyani, Kalyani, WB 741235, India
AU: Chakraborty, S
EM: chakrabortysudipta@hotmail.com
AF: Department of Chemistry, University of Kalyani, Kalyani, WB 741235, India
AU: Chakraborty, S
EM: chakrabortysudipta@hotmail.com
AF: LGIT-OSUG, University of Grenoble-I, Grenoble Cedex 9, F-38041, France
AU: Jean, J
EM: jiinshuh@mail.ncku.edu.tw
AF: Department of Earth Sciences, National Cheng Kung University
1 University Road, Tainan, 70101, Taiwan
AU: Charlet, L
EM: bibhash12@yahoo.com
AF: LGIT-OSUG, University of Grenoble-I, Grenoble Cedex 9, F-38041, France
AU: Chatterjeee, D
EM: dbchat2001@yahoo.co.in
AF: Department of Chemistry, University of Kalyani, Kalyani, WB 741235, India
AB:
Sixty-six groundwater samples were collected from an area of 16 sq. km in Chakdaha block, West Bengal. High
arsenic (1 to 475 μg/l) in anoxic groundwater is associated with relatively high Fe and pCO2.
Groundwater redox potential is controlled by the Fe2+/Fe(OH)3 couple. X-ray fluorescence (XRF) analyses of 29
borehole sediments showed higher contents of As (8-14 mg/kg), Fe2O3 (5-9.6%) and MnO (0.07-0.15%) in silty
clay whereas fine to medium sand have lower content of As (<5 mg/kg), Fe2O3 (1.15-3.9%) and MnO (0.02-
0.06%). Acid extractable As does not correlate with ascorbate extractable Fe oxyhydroxide. However, high Fe
oxyhydroxide (10-12 g/kg) was obtained by ascorbate extraction in low As area. Organic carbon is low ~ 1% and
groundwater temperature (26-31oC) may facilitate microbial process that leads to increase local reducing
condition (redox traps). Speciation of Fe, Mn, HCO3- and As in groundwater samples was done by using
MINTEQA2. Arsenate adsorption study performed on sandy riverbank sediment indicates very low affinity for As at
pH ~7.5.
DE: 0792 Contaminants (0432)
DE: 1009 Geochemical modeling (3610, 8410)
DE: 1051 Sedimentary geochemistry
DE: 1065 Major and trace element geochemistry
DE: 1831 Groundwater quality
SC: Hydrology [H]
MN: 2007 Fall Meeting