Redox control of arsenic mobilization in Bangladesh groundwater

Y. Zheng, M. Stute, A. Van Geen, I. Gavrieli, R. Dhar, H. J. Simpson, Peter Schlosser, K. M. Ahmed

Research output: Contribution to journalArticle

283 Citations (Scopus)

Abstract

Detailed hydrochemical measurements, δ34SSO4 and 3H analyses were performed on 37 groundwater samples collected during February 1999, January and March 2000 from 6 locations in eastern and southeastern Bangladesh to examine redox processes that lead to As mobilization in groundwater. The study sites were chosen based on available nation-wide As surveys to span the entire spectrum of As concentrations in Bangladesh groundwater, and to represent 3 of 5 major geological units of the Ganges-Brahmaputra Delta: uplifted Pleistocene terrace, fluvial flood plain and delta plain. Arsenic was found to be mobilized under Fe-reducing conditions in shallow aquifers (<35 m depth), presumably of Holocene age. It remained mobile under SO4-reducing conditions, suggesting that authigenic sulfide precipitation does not constitute a significant sink for As in these groundwaters. The redox state of the water was characterized by a variety of parameters including dissolved O2, NO3 -, Mn2+, Fe2+ concentrations, and SO4 2-/Cl- ratios. High dissolved [As] (> 50 μg/l; or > 0.7 μM ) were always accompanied by high dissolved [HCO3 -] (> 4 mM), and were close to saturation with respect to calcite. Groundwater enriched in As (200-800 μg/l; or 2.7-10.7 μM) and phosphate (30-100 μM) but relatively low in dissolved Fe (5-40 μM) probably resulted from re-oxidation of reducing, As and Fe enriched water. This history was deduced from isotopic signatures of δ34SSO4 and 3H2O (3H) to delineate the nature of redox changes for some of the reducing groundwaters. In contrast, As is not mobilized in presumed Pleistocene aquifers, both shallow (30-60 m) and deep (150-270 m), because conditions were not reducing enough due to lack of sufficient O 2 demand.

Original languageEnglish (US)
Pages (from-to)201-214
Number of pages14
JournalApplied Geochemistry
Volume19
Issue number2
DOIs
StatePublished - Jan 1 2004
Externally publishedYes

Fingerprint

Arsenic
mobilization
Groundwater
arsenic
groundwater
Aquifers
aquifer
Pleistocene
Calcium Carbonate
Calcite
terrace
Phosphates
calcite
phosphate
Oxidation-Reduction
saturation
oxidation
Oxidation
Water
history

ASJC Scopus subject areas

  • Environmental Chemistry
  • Pollution
  • Geochemistry and Petrology

Cite this

Zheng, Y., Stute, M., Van Geen, A., Gavrieli, I., Dhar, R., Simpson, H. J., ... Ahmed, K. M. (2004). Redox control of arsenic mobilization in Bangladesh groundwater. Applied Geochemistry, 19(2), 201-214. https://doi.org/10.1016/j.apgeochem.2003.09.007

Redox control of arsenic mobilization in Bangladesh groundwater. / Zheng, Y.; Stute, M.; Van Geen, A.; Gavrieli, I.; Dhar, R.; Simpson, H. J.; Schlosser, Peter; Ahmed, K. M.

In: Applied Geochemistry, Vol. 19, No. 2, 01.01.2004, p. 201-214.

Research output: Contribution to journalArticle

Zheng, Y, Stute, M, Van Geen, A, Gavrieli, I, Dhar, R, Simpson, HJ, Schlosser, P & Ahmed, KM 2004, 'Redox control of arsenic mobilization in Bangladesh groundwater', Applied Geochemistry, vol. 19, no. 2, pp. 201-214. https://doi.org/10.1016/j.apgeochem.2003.09.007
Zheng Y, Stute M, Van Geen A, Gavrieli I, Dhar R, Simpson HJ et al. Redox control of arsenic mobilization in Bangladesh groundwater. Applied Geochemistry. 2004 Jan 1;19(2):201-214. https://doi.org/10.1016/j.apgeochem.2003.09.007
Zheng, Y. ; Stute, M. ; Van Geen, A. ; Gavrieli, I. ; Dhar, R. ; Simpson, H. J. ; Schlosser, Peter ; Ahmed, K. M. / Redox control of arsenic mobilization in Bangladesh groundwater. In: Applied Geochemistry. 2004 ; Vol. 19, No. 2. pp. 201-214.
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