title: Arsenic mobilization in the aquifers of three physiographic settings of West Bengal, India: understanding geogenic and anthropogenic influences.
abstract: A comparative hydrogeochemical study was carried out in West Bengal, India covering three physiographic regions, Debagram and Chakdaha located in the Bhagirathi-Hooghly alluvial plain and Baruipur in the delta front, to demonstrate the control of geogenic and anthropogenic influences on groundwater arsenic (As) mobilization. Groundwater samples (n = 90) from tube wells were analyzed for different physico-chemical parameters. The low redox potential (Eh = -185 to -86 mV) and dominant As(III) and Fe(II) concentrations are indicative of anoxic nature of the aquifer. The shallow (<100 m) and deeper (>100 m) aquifers of Bhagirathi-Hooghly alluvial plains as well as shallow aquifers of delta front are characterized by Ca(2+)HCO3(-) type water, whereas Na(+) and Cl(-) enrichment is found in the deeper aquifer of delta front. The equilibrium of groundwater with respect to carbonate minerals and their precipitation/dissolution seems to be controlling the overall groundwater chemistry. The low SO4(2-) and high DOC, PO4(3-) and HCO3(-) concentrations in groundwater signify ongoing microbial mediated redox processes favoring As mobilization in the aquifer. The As release is influenced by both geogenic (i.e. geomorphology) and anthropogenic (i.e. unsewered sanitation) processes. Multiple geochemical processes, e.g., Fe-oxyhydroxides reduction and carbonate dissolution, are responsible for high As occurrence in groundwaters.
authors.affiliation: Faculty of Sciences, University of Girona, Campus de Montilivi, 17071 Girona, Spain; Department of Chemistry, University of Kalyani, Kalyani 741235, West Bengal, India. Electronic address: subhamoy081984@gmail.com.
authors.forename: Subhamoy
authors.initials: S
authors.lastname: Bhowmick
authors.forename: Bibhash
authors.initials: B
authors.lastname: Nath
authors.forename: Dipti
authors.initials: D
authors.lastname: Halder
authors.forename: Ashis
authors.initials: A
authors.lastname: Biswas
authors.forename: Santanu
authors.initials: S
authors.lastname: Majumder
authors.forename: Priyanka
authors.initials: P
authors.lastname: Mondal
authors.forename: Sudipta
authors.initials: S
authors.lastname: Chakraborty
authors.forename: Jerome
authors.initials: J
authors.lastname: Nriagu
authors.forename: Prosun
authors.initials: P
authors.lastname: Bhattacharya
authors.forename: Monica
authors.initials: M
authors.lastname: Iglesias
authors.forename: Gabriela
authors.initials: G
authors.lastname: Roman-Ross
authors.forename: Debendranath
authors.initials: D
authors.lastname: Guha Mazumder
authors.forename: Jochen
authors.initials: J
authors.lastname: Bundschuh
authors.forename: Debashis
authors.initials: D
authors.lastname: Chatterjee
mesh_terms: D001151:Arsenic / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D002254:Carbonates / Q000737:chemistry; D002384:Catalysis; D004784:Environmental Monitoring / Q000379:methods; D005296:Ferrous Compounds / Q000737:chemistry; D005618:Fresh Water / Q000737:chemistry; D005843:Geography; D019015:Geologic Sediments; D005844:Geology; D060587:Groundwater / Q000032:analysis* / Q000737:chemistry*; D006878:Hydroxides / Q000737:chemistry; D007194:India; D007501:Iron / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D011891:Rain; D045483:Rivers; D012621:Seasons; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000032:analysis; D018508:Water Purification / Q000379:methods*
chemical_list: D002254:Carbonates; D005296:Ferrous Compounds; D006878:Hydroxides; D014874:Water Pollutants, Chemical; D002244:Carbon; D007501:Iron; D001151:Arsenic; D010100:Oxygen