Hydrogen thresholds and steady-state concentrations associated with microbial arsenate respiration
| Autor: | Flemming Larsen, Mai Thanh Duc, Christian Blodau, Axel Colin Heimann, Pham Quy Nhan, Dieke Postma, Rasmus Jakobsen, Nguyen Thi Hue, Pham Hung Viet, Søren Jessen |
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| Rok vydání: | 2007 |
| Předmět: |
Geologic Sediments
Molar concentration Chromatography Gas Population Mineralogy chemistry.chemical_compound Respiration Environmental Chemistry education Arsenite education.field_of_study Chemistry Arsenate General Chemistry Anoxic waters Biodegradation Environmental Vietnam Environmental chemistry Arsenates Thermodynamics Environmental Pollutants Epsilonproteobacteria Steady state (chemistry) Anaerobic exercise Methane Hydrogen |
| Zdroj: | Environmental sciencetechnology. 41(7) |
| ISSN: | 0013-936X |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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