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| Titel |
Anaerobic methane oxidation may be more prevalent in surface soils than was originally thought |
| VerfasserIn |
Mathieu Gauthier, Robert L. Bradley, Miloslav Šimek |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250084846
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| Zusammenfassung |
| Anaerobic oxidation of methane (CH4) (AOM) is a process that was first reported to occur in
deep anoxic marine sediments. In this environment, CH4 is oxidized with sulphate (SO42-)
as the terminal electron acceptor. It is mediated by a syntrophic consortium formed by SO42-
reducing bacteria and anaerobic CH4 oxidizing Archaea, or by the latter alone. Since this
landmark discovery, AOM was found to occur in other environments including
freshwater lake sediments and water columns, mud volcanoes, landfill leachate,
deep buried Holocene sediments and hydrocarbon contaminated aquifers. All of
these situations are very specific and point to AOM as being primarily occurring
in highly reducing conditions. Thus, observations of AOM in surface soils with
fluctuating REDOX conditions are relatively scarce, although a few independent studies
have reported AOM in surface peatlands as well as in a forest soil. Furthermore,
AOM may follow different pathways, such as via the coupled oxidation of CH4 and
reduction of manganese (Mn(IV)) or iron (Fe(III)), or by a lone denitrifying species that
converts nitrite to nitric oxide in order to generate O2 that is then used internally
to oxidize CH4. Thus, the goal of our study was to determine whether AOM is
more prevalent than was thought in hydromorphic surface soils across different
environments, and whether the addition of NO3- or SO4= as alternative electron
acceptors may stimulate the process. We collected samples from 3 peatland soils in
Scotland, 2 acid-sulphate soils in Finland, and shore sediments of 15 drained fish
ponds in the Czech Republic. Subsamples were incubated in the absence of O2 and
amended with either NO3-, SO42-, or left unamended (control). The net flux of CH4
and CO2 were assessed by gas chromatography after 2, 20, 40 and 60 days. We
also used a 13C-CH4 isotope dilution technique to determine gross production and
consumption rates of CH4. We detected AOM in all of our soils, with oxidation
rates ranging between 0.001 and 37.28 nmol g-1 day-1, suggesting that AOM
may be more ubiquitous than was originally thought. On the other hand, no clear
patterns emerged as to the effects of NO3- or SO42- amendments on this process. |
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