Molecular biogeochemistry of sulfate reduction, methanogenesis and the anaerobic oxidation of methane at Gulf of Mexico cold seeps

Orcutt, B.; Boetius, Antje; Elvert, Marcus; Samarkin, V.; Joye, Samantha B.

doi:10.1016/j.gca.2005.04.012

Cited by 206 publications

(237 citation statements)

References 102 publications

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“…Rates were sustained over a range of in situ temperatures (Table 1 and Supplementary Table 1), suggesting this process is widespread in FWW systems throughout the year. Strikingly, the FWW rates are comparable in magnitude with those documented in marine systems 35,52 . AOM rates were similar to or exceeded rates of methane production from acetate and hydrogen (the two major methanogenic substrates 53 ) within the depth range assayed (Table 1).…”

Section: Discussionsupporting

confidence: 55%

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High rates of anaerobic methane oxidation in freshwater wetlands reduce potential atmospheric methane emissions

et al. 2015

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The role of anaerobic oxidation of methane (AOM) in wetlands, the largest natural source of atmospheric methane, is poorly constrained. Here we report rates of microbially mediated AOM (average rate ¼ 20 nmol cm À 3 per day) in three freshwater wetlands that span multiple biogeographical provinces. The observed AOM rates rival those in marine environments. Most AOM activity may have been coupled to sulphate reduction, but other electron acceptors remain feasible. Lipid biomarkers typically associated with anaerobic methane-oxidizing archaea were more enriched in 13 C than those characteristic of marine systems, potentially due to distinct microbial metabolic pathways or dilution with heterotrophic isotope signals. On the basis of this extensive data set, AOM in freshwater wetlands may consume 200 Tg methane per year, reducing their potential methane emissions by over 50%. These findings challenge precepts surrounding wetland carbon cycling and demonstrate the environmental relevance of an anaerobic methane sink in ecosystems traditionally considered strong methane sources.

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Section: Discussionsupporting

confidence: 55%

“…Rates of hydrogenotrophic methanogenesis ( 14 CH 4 from H 14 CO 3 À ) and acetoclastic methanogenesis ( 14 CH 4 from 2-14 CH 3 COO À ) were performed, processed and calculated using previously published methods 52 . The recovery rate of labelled methane was 495%.…”

Section: (Hplc)mentioning

confidence: 99%

High rates of anaerobic methane oxidation in freshwater wetlands reduce potential atmospheric methane emissions

et al. 2015

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“…6) provide evidence for methanogenesis in Batumi surface sediments. Methanogenesis in sulfate-bearing sediments was previously verified in the Pacific Ocean (Parkes et al, 2005), in the Gulf of Mexico (Orcutt et al, 2005(Orcutt et al, , 2008, and in the Northwestern Black Sea (Knab et al, 2008), as well as during in vitro studies on AOM-performing microbial consortia under the presence of methane and sulfate (Seifert et al, 2006;Treude et al, 2007). Therefore, we conclude that AOM in surface sediments of the Batumi seep area is spatially accompanied by microbial formation of 13 C-depleted methane, which in type I ss gas over-compensates a general 13 C-enrichement in methane left from the AOM.…”

Section: Methane Consumption and Production In Shallow Sedimentsmentioning

confidence: 84%

Molecular and isotopic partitioning of low-molecular-weight hydrocarbons during migration and gas hydrate precipitation in deposits of a high-flux seepage site

et al. 2010

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Detailed knowledge of the extent of post-genetic modifications affecting shallow submarine hydrocarbons fueled from the deep subsurface is fundamental for evaluating source and reservoir properties. We investigated gases from a submarine high-flux seepage site in the anoxic Eastern Black Sea in order to elucidate molecular and isotopic alterations of low-molecular-weight hydrocarbons (LMWHC) associated with upward migration through the sediment and precipitation of shallow gas hydrates. For this, nearsurface sediment pressure cores and free gas venting from the seafloor were collected using autoclave technology at the Batumi seep area at 845 m water depth within the gas hydrate stability zone. Vent gas, gas from pressure core degassing, and from hydrate dissociation were strongly dominated by methane (> 99.85 mol.% of ∑[C 1 -C 4 , CO 2 ]). Molecular ratios of LMWHC (C 1 /[C 2 + C 3 ] > 1000) and stable isotopic compositions of methane (δ 13 C = − 53.5‰ V-PDB; D/H around − 175‰ SMOW) indicated predominant microbial methane formation. C 1 /C 2+ ratios and stable isotopic compositions of LMWHC distinguished three gas types prevailing in the seepage area. Vent gas discharged into bottom waters was depleted in methane by > 0.03 mol.% (∑[C 1 -C 4 , CO 2 ]) relative to the other gas types and the virtual lack of 14 C-CH 4 indicated a negligible input of methane from degradation of fresh organic matter. Of all gas types analyzed, vent gas was least affected by molecular fractionation, thus, its origin from the deep subsurface rather than from decomposing hydrates in near-surface sediments is likely. As a result of the anaerobic oxidation of methane, LMWHC in pressure cores in top sediments included smaller methane fractions [0.03 mol.% ∑(C 1 -C 4 , CO 2 )] than gas released from pressure cores of more deeply buried sediments, where the fraction of methane was maximal due to its preferential incorporation in hydrate lattices. No indications for stable carbon isotopic fractionations of methane during hydrate crystallization from vent gas were found. Enrichments of 14 C-CH 4 (1.4 pMC) in short cores relative to lower abundances (max. 0.6 pMC) in gas from long cores and gas hydrates substantiates recent methanogenesis utilizing modern organic matter deposited in top sediments of this high-flux hydrocarbon seep area.

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“…Sulfatereduction rates determined at such sites often exceeded the rates attributed to anaerobic oxidation of methane by several fold (Bowles et al, 2011), and have been proposed to be due to oxidation of hydrocarbons other than methane, including shortchain alkanes Kallmeyer and Boetius 2004;Orcutt et al, 2005Orcutt et al, , 2010Niemann et al, 2006;Kleindienst et al, 2012). Propane-and butane-degrading sulfate reducers may contribute significantly to the excess sulfate-reduction rates, and could have an important role for the in situ carbon and sulfur cycling.…”

Section: Discussionmentioning

confidence: 99%

Anaerobic degradation of propane and butane by sulfate-reducing bacteria enriched from marine hydrocarbon cold seeps

et al. 2012

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The short-chain, non-methane hydrocarbons propane and butane can contribute significantly to the carbon and sulfur cycles in marine environments affected by oil or natural gas seepage. In the present study, we enriched and identified novel propane and butane-degrading sulfate reducers from marine oil and gas cold seeps in the Gulf of Mexico and Hydrate Ridge. The enrichment cultures obtained were able to degrade simultaneously propane and butane, but not other gaseous alkanes. They were cold-adapted, showing highest sulfate-reduction rates between 16 and 20 1C. Analysis of 16S rRNA gene libraries, followed by whole-cell hybridizations with sequence-specific oligonucleotide probes showed that each enrichment culture was dominated by a unique phylotype affiliated with the Desulfosarcina-Desulfococcus cluster within the Deltaproteobacteria. These phylotypes formed a distinct phylogenetic cluster of propane and butane degraders, including sequences from environments associated with hydrocarbon seeps. Incubations with 13 C-labeled substrates, hybridizations with sequence-specific probes and nanoSIMS analyses showed that cells of the dominant phylotypes were the first to become enriched in 13 C, demonstrating that they were directly involved in hydrocarbon degradation. Furthermore, using the nanoSIMS data, carbon assimilation rates were calculated for the dominant cells in each enrichment culture.

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Molecular biogeochemistry of sulfate reduction, methanogenesis and the anaerobic oxidation of methane at Gulf of Mexico cold seeps

Cited by 206 publications

References 102 publications

High rates of anaerobic methane oxidation in freshwater wetlands reduce potential atmospheric methane emissions

High rates of anaerobic methane oxidation in freshwater wetlands reduce potential atmospheric methane emissions

Molecular and isotopic partitioning of low-molecular-weight hydrocarbons during migration and gas hydrate precipitation in deposits of a high-flux seepage site

Anaerobic degradation of propane and butane by sulfate-reducing bacteria enriched from marine hydrocarbon cold seeps

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