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| Titel |
Anaerobic oxidation of methane: an underappreciated aspect of methane cycling in peatland ecosystems? |
| VerfasserIn |
K. A. Smemo, J. B. Yavitt |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 8, no. 3 ; Nr. 8, no. 3 (2011-03-24), S.779-793 |
| Datensatznummer |
250005578
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| Publikation (Nr.) |
 copernicus.org/bg-8-779-2011.pdf |
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| Zusammenfassung |
| Despite a large body of literature on microbial anaerobic oxidation of
methane (AOM) in marine sediments and saline waters and its importance to
the global methane (CH4) cycle, until recently little work has
addressed the potential occurrence and importance of AOM in non-marine
systems. This is particularly true for peatlands, which represent both a
massive sink for atmospheric CO2 and a significant source of
atmospheric CH4. Our knowledge of this process in peatlands is
inherently limited by the methods used to study CH4 dynamics in soil
and sediment and the assumption that there are no anaerobic sinks for
CH4 in these systems. Studies suggest that AOM is CH4-limited and
difficult to detect in potential CH4 production assays against a
background of CH4 production. In situ rates also might be elusive due to
background rates of aerobic CH4 oxidation and the difficulty in
separating net and gross process rates. Conclusive evidence for the electron
acceptor in this process has not been presented. Nitrate and sulfate are
both plausible and favorable electron acceptors, as seen in other systems,
but there exist theoretical issues related to the availability of these ions
in peatlands and only circumstantial evidence suggests that these pathways
are important. Iron cycling is important in many wetland systems, but recent
evidence does not support the notion of CH4 oxidation via dissimilatory
Fe(III) reduction or a CH4 oxidizing archaea in consortium with an
Fe(III) reducer. Calculations based on published rates demonstrate that AOM
might be a significant and underappreciated constraint on the global
CH4 cycle, although much about the process is unknown, in vitro rates may not
relate well to in situ rates, and projections based on those rates are fraught with
uncertainty. We suggest electron transfer mechanisms, C flow and pathways,
and quantifying in situ peatland AOM rates as the highest priority topics for
future research. |
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