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Journal Article: Release and transport of As into aquifers BGD

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  • Suiling Wang
    http://snipurl.com/l456 [redirects to full URL
    Message 1 of 1 , Dec 28, 2005
      http://snipurl.com/l456 [redirects to full URL

      Processes conducive to the release and transport of arsenic into
      aquifers of Bangladesh. ML Polizzotto, CF Harvey, SR Sutton, and S
      Fendorf, Environ Sci, 2005, 102, 18819-18823.

      Abstract: Arsenic is a contaminant in the groundwater of Holocene aquifers in
      Bangladesh, where around 57 million people drink water with arsenic levels
      exceeding the limits set by the World Health Organization. Although arsenic is
      native to the sediments, the means by which it is released to groundwater
      remains unresolved. Contrary to the current paradigm, ferric (hydr)oxides
      appear to dominate the partitioning of arsenic in the near surface but have a
      limited impact at aquifer depths where wells extract groundwater with high
      arsenic concentrations. We present a sequence of evidence that, taken together,
      suggest that arsenic may be released in the near surface and then transported
      to depth. We establish that (i) the only portion of the sediment profile with
      conditions destabilizing to arsenic in our analysis is in the surface or
      near-surface environment; (ii) a consistent input of arsenic via sediment
      deposition exists; (iii) retardation of arsenic transport is limited in the
      aquifers; and (iv) groundwater recharge occurs at a rate sufficient to
      necessitate continued input of arsenic to maintain observed concentrations. Our
      analyses thus lead to the premise that arsenic is liberated in surface and
      near-surface sediments through cyclic redox conditions and is subsequently
      transported to well depth. Influx of sediment and redox cycling provide a
      long-term source of arsenic that when liberated in the near surface is only
      weakly partitioned onto sediments deeper in the profile and is transported
      through aquifers by groundwater recharge.
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