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Anoxic oxidation of arsenite linked to denitrification in sludges and sediments.

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Water research

Elsevier BV

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      Abstract

      In this study, denitrification linked to the oxidation of arsenite (As(III)) to arsenate (As(V)) was shown to be a widespread microbial activity in anaerobic sludge and sediment samples that were not previously exposed to arsenic contamination. When incubated with 0.5mM As(III) and 10mM NO(3)(-), the anoxic oxidation of As(III) commenced within a few days, achieving specific activities of up to 1.24mmol As(V) formed g(-1) volatile suspended solids d(-1) due to growth (doubling times of 0.74-1.4d). The anoxic oxidation of As(III) was partially to completely inhibited by 1.5 and 5mM As(III), respectively. Inhibition was minimized by adding As(III) adsorbed onto activated aluminum (AA). The oxidation of As(III) was shown to be linked to the complete denitrification of NO(3)(-) to N(2) by demonstrating a significantly enhanced production of N(2) beyond the background endogenous production as a result of adding As(III)-AA to the cultures. The N(2) production corresponded closely the expected stoichiometry of the reaction, 2.5mol As(III) mol(-1)N(2)-N. The oxidation of As(III) linked to the use of common-occurring nitrate as an electron acceptor may be an important missing link in the biogeochemical cycling of arsenic.

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      Affiliations
      [1 ] Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, USA.
      Journal
      Water Res.
      Water research
      Elsevier BV
      0043-1354
      0043-1354
      Nov 2008
      : 42
      : 17
      18762312 S0043-1354(08)00322-9 10.1016/j.watres.2008.08.004 2614353 NIHMS75462

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