Hypersulfidic deep biosphere indicates extreme sulfur isotope fractionation during single-step microbial sulfate reduction

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doi: 10.1130/0091-7613(2001)029<0647:HDBIES>2.0.CO;2
Author(s): Wortmann, Ulrich G.; Bernasconi, Stefano M.; Böttcher, Michael E.
Author Affiliation(s): Primary:
GEOMAR Research Center for Marine Geosciences, Kiel, Federal Republic of Germany
ETH-Zürich, Switzerland
Max-Planck Institute for Marine Microbiology, Federal Republic of Germany
Volume Title: Geology (Boulder)
Source: Geology (Boulder), 29(7), p.647-650. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613 CODEN: GLGYBA
Note: In English. Includes appendix. 33 refs.; illus., incl. sketch map
Summary: Coexisting dissolved sulfide and sulfate from hypersulfidic interstitial waters of a 380- m-long sediment core show a large isotopic difference of up to 72 per mil caused by in situ microbial sulfate reduction. This is considerably larger than the assumed biological maximum of 46 per mil derived from laboratory studies with pure cultures of sulfate-reducing bacteria. Similar high fractionations inferred from sedimentary metal sulfides have been previously explained by a multistage process, involving sulfide reoxidation and disproportionation of sulfur intermediates. Our data show that extreme isotopic differences between sulfate and the reduced sulfur species can also be generated during microbial single-step fractionation. This result indicates that the sulfate-reducing communities and/or their cellular metabolic activities in the deep biosphere may differ from those observed in near-surface sediments or the water column.
Year of Publication: 2001
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 07 Marine Geology and Oceanography; Bacteria; Biogenic processes; Biosphere; Chloride ion; Chlorine; Cores; Deep-sea environment; Geochemistry; Great Australian Bight; Halogens; Hydrochemistry; In situ; Indian Ocean; Isotope fractionation; Isotope ratios; Isotopes; Leg 182; Marine environment; Marine sediments; Microorganisms; Numerical models; ODP Site 1130; Ocean Drilling Program; PH; Pore water; Reduction; S-34/S-32; Sample preparation; Sediments; Solutes; Stable isotopes; Sulfate ion; Sulfides; Sulfur
Coordinates: S332512 S332512 E1273608 E1273608
Record ID: 2001051505
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