Influence of H(2)  and O(2)  on sulphate-reducing activity of a subterranean community and the coupled response in redox potential.
Deep Fennoscandian groundwater is anaerobic, reducing in character and populated by a large diversity of obligate and facultative anaerobic microorganisms. Concentrations of H(2) and carbon monoxide are often 0.01-1 μM and of dissolved organic carbon (DOC) and methane 0.01-1 mM. Microbial activity involving these electron and energy donors may help keep deep groundwater anaerobic and reduced. H(2) was added in concentrations of 0.1-10 mM to a sulphate-reducing community attached to crushed rock in groundwater under a pressure of 2.0 MPa and in situ geochemical conditions. Experiments reported a threshold concentration of approximately 1 μM H(2) at which sulphate reduction ceased, despite the presence of DOC and acetate, suggesting that H(2) was needed for sulphate-reducing activity. δ(13)C values of acetate and DOC data suggested that organic material was degraded to acetate by means of a heterotrophic process. New pressure-resistant micro-sensors for measuring E(h) indicated an H(2)-concentration-dependent decrease in E(h). The investigated community rapidly mitigated the increase in E(h) caused by repeated additions of 0.1-0.2 mM pulses of O(2) as long as H(2) was available. The results imply that sulphate reduction to sulphide with H(2) may dominate sulphate-rich groundwater, which may have implications for metallic underground constructions.
Microbial Analytics Sweden AB, Mölnlycke, Sweden. kap@micans.se
Karsten
K
Pedersen
D001419:Bacteria / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism; D060587:Groundwater / Q000737:chemistry* / Q000382:microbiology*; D052836:Heterotrophic Processes; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000378:metabolism; D010084:Oxidation-Reduction; D013431:Sulfates / Q000378:metabolism*; D013440:Sulfides / Q000378:metabolism
D013431:Sulfates; D013440:Sulfides; D002244:Carbon; D008697:Methane