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| Titel |
Methane oxidation associated to submerged brown-mosses buffers methane emissions from Siberian polygonal peatlands |
| VerfasserIn |
Susanne Liebner, Josef Zeyer, Christian Knoblauch |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250033001
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| Zusammenfassung |
| Circumpolar peatlands store roughly 18Â % of the globally stored carbon in soils [based on
1, 2]. Also, northern wetlands and tundra are a net source of methane (CH4), an
effective greenhouse gas (GHG), with an estimated annual CH4 release of 7.2% [3]
or 8.1% [4] of the global total CH4 emission. Although it is definite that Arctic
tundra significantly contributes to the global methane emissions in general, regional
variations in GHG fluxes are enormous. CH4 fluxes of polygonal tundra within
the Siberian Lena Delta, for example, were reported to be low [5, 6], particularly
at open water polygonal ponds and small lakes [7] which make up around 10Â %
of the delta’s surface. Low methane emissions from polygonal ponds oppose that
Arctic permafrost thaw ponds are generally known to emit large amounts of CH4
[8].
Combining tools of biogeochemistry and molecular microbiology, we identified sinks of
CH4 in polygonal ponds from the Lena Delta that were not considered so far in GHG studies
from Arctic wetlands. Pore water CH4 profiling in polygonal ponds on Samoylov, a small
island in the central part of the Lena Delta, revealed a pronounced zone of CH4 oxidation
near the vegetation surface in submerged layers of brown-mosses. Here, potential CH4
oxidation was an order of magnitude higher than in non-submerged mosses and in
adjacent bulk soil. We could additionally show that this moss associated methane
oxidation (MAMO) is hampered when exposure of light is prevented. Shading of plots
with submerged Scorpidium scorpioides inhibited MAMO leading to higher CH4
concentrations and an increase in CH4 fluxes by a factor of ~13. Compared to
non-submerged mosses, the submerged mosses also showed significantly lower δ13C
values indicating that they use carbon dioxide derived from methane oxidation for
photosynthesis. Applying stable isotope probing of DNA, type II methanotrophs were
identified to be responsible for the oxidation of CH4 in the submerged Scorpidium
scorpioides.
Our study gives first evidence for MAMO in submerged brown-mosses and in the
oligotrophic polygonal peatlands of the Lena Delta. It shows that MAMO might
effectively reduce methane fluxes to the atmosphere also in Arctic GHG emission hot
spots.
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