Hydrogen thresholds and steady-state concentrations associated with microbial arsenate respiration

Axel C. Heimann, Christian Blodau, Dieke Postma, Flemming Larsen, Pham H. Viet, Pham Q. Nhan, Søren Jessen, Mai T. Duc, Nguyen T.M. Hue, Rasmus Jakobsen

Research output: Contribution to journalArticleResearchpeer-review

22 Citations (Scopus)


H2 thresholds for microbial respiration of arsenate (As(V)) were investigated in a pure culture of Sulfurospirillum arsenophilum. H2 was consumed to threshold concentrations of 0.03-0.09 nmol/L with As(V) as terminal electron acceptor, allowing for a Gibbs free-energy yield of 36-41 kJ per mol of reaction. These thresholds are among the lowest measured for anaerobic respirers and fall into the range of denitrifiers or Fe(III)-reducers. In sediments from an arsenic-contaminated aquifer in the Red River flood plain, Vietnam, H2 levels decreased to 0.4-2 nmol/L when As(V) was added under anoxic conditions. When As(V) was depleted, H2 concentrations rebounded by a factor of 10, a level similar to that observed in arsenic-free controls. The sediment-associated microbial population completely reduced millimolar levels of As(V) to arsenite (As(III)) within a few days. The rate of As(V)-reduction was essentially the same in sediments amended with a pure culture of S. arsenophilum. These findings together with a review of observed H2 threshold and steady-state values suggest that microbial As(V)-respirers have a competitive advantage over several other anaerobic respirers through their ability to thrive at low H2 levels.

Original languageEnglish
Pages (from-to)2311-2317
Number of pages7
JournalEnvironmental Science and Technology
Issue number7
Publication statusPublished - 1 Apr 2007
Externally publishedYes

Programme Area

  • Programme Area 2: Water Resources


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