Distribution of arsenic and its mobility in shallow aquifer sediments from Ambikanagar, West Bengal, India
2011 (English)In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 26, no 4, 505-515 p.Article in journal (Refereed) Published
Sediments from a core retrieved during installation of a shallow drinking water well in Ambikanagar (West Bengal, India) were analyzed for various physical and chemical parameters. The geochemical analyses included: (1) a 4-step sequential extraction scheme to determine the distribution of As between different fractions, (2) As speciation (As(3+) vs. As(5+)), and (3) C, N and S isotopes. The sediments have a low percentage of organic C and N (0.10-0.56% and 0.01-0.05%, respectively). Arsenic concentration is between 2 and 7 mg kg(-1), and it is mainly associated with the residual fraction, less susceptible to chemical weathering. The proportion of As(3+) in these sediments is high and ranges from 24% to 74%. Arsenic in the second fraction (reducible) correlates well with Mn, and in the residual fraction As correlates well with several transition elements. The stable isotope results indicate microbial oxidation of organic matter involving SO(4) reduction. Oxidation of primary sulfide minerals and release of As from reduction of Fe(oxy)hydroxides do not seem important mechanisms in As mobilization. Instead, the dominance of As(3+) and presence of As(5+) reducing microorganisms in this shallow aquifer imply As remobilization involving microbial processes that needs further investigations.
Place, publisher, year, edition, pages
2011. Vol. 26, no 4, 505-515 p.
Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:su:diva-68808DOI: 10.1016/j.apgeochem.2011.01.009ISI: 000289384200009OAI: oai:DiVA.org:su-68808DiVA: diva2:474562
authorCount :22012-01-092012-01-072012-01-09Bibliographically approved