High-Arsenic Groundwater in the Southwestern Bengal Basin Caused by a Lithologically Controlled Deep Flow System

M. R. Khan, H. A. Michael, B. Nath, B. L. Huhmann, C. F. Harvey, A. Mukherjee, I. Choudhury, M. Chakraborty, M. S. Ullah, K. M. Ahmed, S. L. Goodbred, P. Schlosser, B. C. Bostick, B. J. Mailloux, T. Ellis, A. van Geen

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Elevated arsenic in Bengal Basin aquifers threatens human health. Most deep (>150 m) groundwater in Pleistocene aquifers is low in arsenic; however higher concentrations have been reported in the southwest border region. Here, we establish that this extensive arsenic contamination at depth is not associated with well failure. A combination of geochemistry and flow modeling constrains the factors that contribute to arsenic contamination at depth in this region. Deep groundwater in the affected area is younger (2.0 ± 0.6 kyr) than deep, low-arsenic groundwater elsewhere (12.0 ± 4.0 kyr) based on radiocarbon. Stratigraphic data indicate pre-Holocene deposition of the contaminated aquifers, but few low-permeability strata. Numerical modeling indicates that this stratigraphic anomaly permits a natural flow system that transports shallow groundwater to depth. Thus, in areas lacking low-permeability layers, arsenic contamination can occur in pre-Holocene aquifers and is probably not an early sign of future deep contamination in regions with interbedded low-permeability strata.

Original languageEnglish (US)
Pages (from-to)13062-13071
Number of pages10
JournalGeophysical Research Letters
Volume46
Issue number22
DOIs
StatePublished - Nov 28 2019
Externally publishedYes

Keywords

  • arsenic
  • Bengal Basin
  • groundwater
  • groundwater dating
  • groundwater modeling
  • water resources

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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    Khan, M. R., Michael, H. A., Nath, B., Huhmann, B. L., Harvey, C. F., Mukherjee, A., Choudhury, I., Chakraborty, M., Ullah, M. S., Ahmed, K. M., Goodbred, S. L., Schlosser, P., Bostick, B. C., Mailloux, B. J., Ellis, T., & van Geen, A. (2019). High-Arsenic Groundwater in the Southwestern Bengal Basin Caused by a Lithologically Controlled Deep Flow System. Geophysical Research Letters, 46(22), 13062-13071. https://doi.org/10.1029/2019GL084767