Role of competing ions in the mobilization of arsenic in groundwater of Bengal Basin: Insight from surface complexation modeling

WATER RESEARCH

卷:55

Article

Biswas, Ashis^1,2  Gustafsson, Jon Petter^1,3  Neidhardt, Harald⁴  Halder, Dipti^1,2  Kundu, Amit K.²  Chatterjee, Debashis²  Berner, Zsolt⁴  Bhattacharya, Prosun¹ 

[1] KTH Royal Inst Technol, Dept Sustainable Dev Environm Sci & Engn, Div Land & Water Resources Engn, KTH Int Groundwater Arsen Res Grp, SE-10044 Stockholm, Sweden

[2] Univ Kalyani, Dept Chem, Kalyani 741235, W Bengal, India

[3] Swedish Univ Agr Sci, Dept Soil & Environm, SE-75007 Uppsala, Sweden

[4] Karlsruhe Inst Technol, Inst Mineral & Geochem, D-76131 Karlsruhe, Germany

关键词: Bengal Basin;    Groundwater;    Arsenic mobilization;    Temporal variability;    Competing ions;    Surface complexation modeling;   

DOI  :  10.1016/j.watres.2014.02.002

来源: Elsevier

【 摘 要 】

This study assesses the role of competing ions in the mobilization of arsenic (As) by surface complexation modeling of the temporal variability of As in groundwater. The potential use of two different surface complexation models (SCMs), developed for ferrihydrite and goethite, has been explored to account for the temporal variation of As(III) and As(V) concentration, monitored in shallow groundwater of Bengal Basin over a period of 20 months. The SCM for ferrihydrite appears as the better predictor of the observed variation in both As(III) and As(V) concentrations in the study sites. It is estimated that among the competing ions, PO43- is the major competitor of As(III) and As(V) adsorption onto Fe oxyhydroxide, and the competition ability decreases in the order PO43- >> Fe(II) > H4SiO4 = HCO- (3.) It is further revealed that a small change in pH can also have a significant effect on the mobility of As(III) and As(V) in the aquifers. A decrease in pH increases the concentration of As(III), whereas it decreases the As(V) concentration and vice versa. The present study suggests that the reductive dissolution of Fe oxyhydroxide alone cannot explain the observed high As concentration in groundwater of the Bengal Basin. This study supports the view that the reductive dissolution of Fe oxyhydroxide followed by competitive sorption reactions with the aquifer sediment is the processes responsible for As enrichment in groundwater. (C) 2014 Elsevier Ltd. All rights reserved.

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