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Bo Barker Jørgensen

Control on rate and pathway of anaerobic organic carbon degradation in the seabed

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The degradation of organic matter in the anoxic seabed proceeds through a complex microbial network in which the terminal steps are dominated by oxidation with sulfate or conversion into methane and CO2. The controls on pathway and rate of the degradation process in different geochemical zones remain elusive. Radiotracer techniques were used to perform measurements of sulfate reduction, methanogenesis, and acetate oxidation with unprecedented sensitivity throughout Holocene sediment columns from the Baltic Sea. We found that degradation rates transition continuously from the sulfate to the methane zone, thereby demonstrating that terminal steps do not exert feedback control on upstream hydrolytic and fermentative processes, as previously suspected. Acetate was a key intermediate for carbon mineralization in both zones. However, acetate was not directly converted into methane. Instead, an additional subterminal step converted acetate to CO2 and reducing equivalents, such as H-2, which then fed autotrophic reduction of CO2 to methane.

Original languageEnglish
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue2
Pages (from-to)367-372
Number of pages6
ISSN0027-8424
DOIs
Publication statusPublished - 9 Jan 2018

    Research areas

  • marine sediment, organic matter mineralization, sulfate reduction methanogenesis, syntrophic acetate oxidation, MOLAL THERMODYNAMIC PROPERTIES, SYNTROPHIC ACETATE OXIDATION, SULFATE-REDUCING BACTERIA, ANOXIC MARINE SEDIMENT, VOLATILE FATTY-ACIDS, METHANE PRODUCTION, BALTIC SEA, HYDROGEN CONCENTRATIONS, TRANSPORT-PROPERTIES, HIGH-PRESSURES

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