Factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment
The carbon isotopic composition of methane produced in anoxic marine sediment is controlled by four factors: (1) the pathway of methane formation, (2) the isotopic composition of the methanogenic precursors, (3) the isotope fractionation factors for methane production, and (4) the isotope fractionat...
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ftcarolinadr:cdr.lib.unc.edu:6d5706100 2023-09-05T13:21:45+02:00 Factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment Alperin, M. J. Blair, N. E. Albert, D. B. Hoehler, T. M. Martens, C. S. Institute of Marine Sciences 1992 https://doi.org/10.17615/e7s6-jy71 https://cdr.lib.unc.edu/downloads/vm40z231r?file=thumbnail https://cdr.lib.unc.edu/downloads/vm40z231r English eng https://doi.org/10.17615/e7s6-jy71 https://cdr.lib.unc.edu/downloads/vm40z231r?file=thumbnail https://cdr.lib.unc.edu/downloads/vm40z231r http://rightsstatements.org/vocab/InC/1.0/ Global Biogeochemical Cycles, 6(3) Isotope stable carbon dioxide Sédiment marin C 13-C 12 oxidation marine sediments methane anaerobic environment lagoonal environment Atlantic Ocean North Carolina C-13/C-12 United States Milieu lagunaire stable isotopes North America sediment-water interface Méthane experimental studies North Atlantic Milieu anaérobie North American Atlantic Article 1992 ftcarolinadr https://doi.org/10.17615/e7s6-jy71 2023-08-19T22:24:01Z The carbon isotopic composition of methane produced in anoxic marine sediment is controlled by four factors: (1) the pathway of methane formation, (2) the isotopic composition of the methanogenic precursors, (3) the isotope fractionation factors for methane production, and (4) the isotope fractionation associated with methane oxidation. The importance of each factor was evaluated by monitoring stable carbon isotope ratios in methane produced by a sediment microcosm. Methane did not accumulate during the initial 42-day period when sediment contained sulfate, indicating little methane production from "noncompetitive" substrates. Following sulfate depletion, methane accumulation proceeded in three distinct phases. First, CO2 reduction was the dominant methanogenic pathway and the isotopic composition of the methane produced ranged from -80 to -94 0/00. The acetate concentration increased during this phase, suggesting that acetoclastic methanogenic bacteria were unable to keep pace with acetate production. Second, acetate fermentation became the dominant methanogenic pathway as bacteria responded to elevated acetate concentrations. The methane produced during this phase was progressively enriched in 13C, reaching a maximum δ13C value of -42 0/00. Third, the acetate pool experienced a precipitous decline from >5 mM to <20 μM and methane production was again dominated by CO2 reduction. The δ 13C of methane produced during this final phase ranged from -46 to -58 0/00. Methane oxidation concurrent with methane production was detected throughout the period of methane accumulation, at rates equivalent to 1 to 8% of the gross methane production rate. Thus methane oxidation was too slow to have significantly modified the isotopic signature of methane. A comparison of microcosm and field data suggests that similar microbial interactions may control seasonal variability in the isotopic composition of methane emitted from undisturbed Cape Lookout Bight sediment. Article in Journal/Newspaper North Atlantic Carolina Digital Repository (UNC - University of North Carolina) Cape Lookout ENVELOPE(156.450,156.450,-83.050,-83.050) Lookout ENVELOPE(77.955,77.955,-68.605,-68.605) |
institution |
Open Polar |
collection |
Carolina Digital Repository (UNC - University of North Carolina) |
op_collection_id |
ftcarolinadr |
language |
English |
topic |
Isotope stable carbon dioxide Sédiment marin C 13-C 12 oxidation marine sediments methane anaerobic environment lagoonal environment Atlantic Ocean North Carolina C-13/C-12 United States Milieu lagunaire stable isotopes North America sediment-water interface Méthane experimental studies North Atlantic Milieu anaérobie North American Atlantic |
spellingShingle |
Isotope stable carbon dioxide Sédiment marin C 13-C 12 oxidation marine sediments methane anaerobic environment lagoonal environment Atlantic Ocean North Carolina C-13/C-12 United States Milieu lagunaire stable isotopes North America sediment-water interface Méthane experimental studies North Atlantic Milieu anaérobie North American Atlantic Alperin, M. J. Blair, N. E. Albert, D. B. Hoehler, T. M. Martens, C. S. Factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment |
topic_facet |
Isotope stable carbon dioxide Sédiment marin C 13-C 12 oxidation marine sediments methane anaerobic environment lagoonal environment Atlantic Ocean North Carolina C-13/C-12 United States Milieu lagunaire stable isotopes North America sediment-water interface Méthane experimental studies North Atlantic Milieu anaérobie North American Atlantic |
description |
The carbon isotopic composition of methane produced in anoxic marine sediment is controlled by four factors: (1) the pathway of methane formation, (2) the isotopic composition of the methanogenic precursors, (3) the isotope fractionation factors for methane production, and (4) the isotope fractionation associated with methane oxidation. The importance of each factor was evaluated by monitoring stable carbon isotope ratios in methane produced by a sediment microcosm. Methane did not accumulate during the initial 42-day period when sediment contained sulfate, indicating little methane production from "noncompetitive" substrates. Following sulfate depletion, methane accumulation proceeded in three distinct phases. First, CO2 reduction was the dominant methanogenic pathway and the isotopic composition of the methane produced ranged from -80 to -94 0/00. The acetate concentration increased during this phase, suggesting that acetoclastic methanogenic bacteria were unable to keep pace with acetate production. Second, acetate fermentation became the dominant methanogenic pathway as bacteria responded to elevated acetate concentrations. The methane produced during this phase was progressively enriched in 13C, reaching a maximum δ13C value of -42 0/00. Third, the acetate pool experienced a precipitous decline from >5 mM to <20 μM and methane production was again dominated by CO2 reduction. The δ 13C of methane produced during this final phase ranged from -46 to -58 0/00. Methane oxidation concurrent with methane production was detected throughout the period of methane accumulation, at rates equivalent to 1 to 8% of the gross methane production rate. Thus methane oxidation was too slow to have significantly modified the isotopic signature of methane. A comparison of microcosm and field data suggests that similar microbial interactions may control seasonal variability in the isotopic composition of methane emitted from undisturbed Cape Lookout Bight sediment. |
author2 |
Institute of Marine Sciences |
format |
Article in Journal/Newspaper |
author |
Alperin, M. J. Blair, N. E. Albert, D. B. Hoehler, T. M. Martens, C. S. |
author_facet |
Alperin, M. J. Blair, N. E. Albert, D. B. Hoehler, T. M. Martens, C. S. |
author_sort |
Alperin, M. J. |
title |
Factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment |
title_short |
Factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment |
title_full |
Factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment |
title_fullStr |
Factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment |
title_full_unstemmed |
Factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment |
title_sort |
factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment |
publishDate |
1992 |
url |
https://doi.org/10.17615/e7s6-jy71 https://cdr.lib.unc.edu/downloads/vm40z231r?file=thumbnail https://cdr.lib.unc.edu/downloads/vm40z231r |
long_lat |
ENVELOPE(156.450,156.450,-83.050,-83.050) ENVELOPE(77.955,77.955,-68.605,-68.605) |
geographic |
Cape Lookout Lookout |
geographic_facet |
Cape Lookout Lookout |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Global Biogeochemical Cycles, 6(3) |
op_relation |
https://doi.org/10.17615/e7s6-jy71 https://cdr.lib.unc.edu/downloads/vm40z231r?file=thumbnail https://cdr.lib.unc.edu/downloads/vm40z231r |
op_rights |
http://rightsstatements.org/vocab/InC/1.0/ |
op_doi |
https://doi.org/10.17615/e7s6-jy71 |
_version_ |
1776202333769695232 |