title: Influences of groundwater extraction on the distribution of dissolved As in shallow aquifers of West Bengal, India.
abstract: Here we report temporal changes of As concentrations in shallow groundwater of the Bengal Delta Plain (BDP). Observed fluctuations are primarily induced by seasonally occurring groundwater movement, but can also be connected to anthropogenic groundwater extraction. Between December 2009 and July 2010, pronounced variations in the groundwater hydrochemistry were recorded in groundwater samples of a shallow monitoring well tapping the aquifer in 22-25 m depth, where Astot concentrations increased within weeks from 100 to 315 μg L(-1). These trends are attributed to a vertically shift of the hydrochemically stratified water column at the beginning of the monsoon season. This naturally occurring effect can be additionally superimposed by groundwater extraction, as demonstrated on a local scale by an in situ experiment simulating extensive groundwater withdrawal during the dry post-monsoon season. Results of this experiment suggest that groundwater extraction promoted an enduring change within the distribution of dissolved As in the local aquifer. Presented outcomes contribute to the discussion of anthropogenic pumping influences that endanger the limited and yet arsenic-free groundwater resources of the BDP.
authors: Institute of Mineralogy and Geochemistry, Karlsruhe Institute of Technology, Adenauerring 20b, D-76133 Karlsruhe, Germany. Electronic address: haraldneid@googlemail.com.
authors: Harald
authors: H
authors: Neidhardt
authors: Zsolt
authors: Z
authors: Berner
authors: Dominik
authors: D
authors: Freikowski
authors: Ashis
authors: A
authors: Biswas
authors: Josef
authors: J
authors: Winter
authors: Debashis
authors: D
authors: Chatterjee
authors: Stefan
authors: S
authors: Norra
mesh_terms: D001151:Arsenic / Q000032:analysis* / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D002980:Climate; D004784:Environmental Monitoring / Q000379:methods*; D019015:Geologic Sediments; D005844:Geology; D060587:Groundwater / Q000737:chemistry*; D007194:India; D010084:Oxidation-Reduction; D011188:Potassium / Q000737:chemistry; D011891:Rain; D012621:Seasons; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification; D014881:Water Supply
chemical_list: D014874:Water Pollutants, Chemical; D014867:Water; D002244:Carbon; D001151:Arsenic; D011188:Potassium
keywords: Arsenic; As(tot); BDP; Bengal Delta Plain; DARPs; DOC; FeRB; GMWL; Groundwater; K; LMWL; Monitoring; Pearson correlation coefficient; Pumping; Spatiotemporal trends; TA; TEA; TOC; coefficient of hydraulic conductivity; dissimilative arsenate respiring prokaryotes; dissolved organic carbon; global meteoric water line; iron-reducing bacteria; local meteoric water line; m bls; meters below land surface; r; terminal electron acceptor; total As concentration; total alkalinity; total organic carbon