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| Titel |
Soil controls on land-atmosphere methane fluxes from an arctic floodplain of the Lena River Delta, Siberia |
| VerfasserIn |
Benjamin Runkle, Alexander Sabrekov, Mikail Glagolev, Lars Kutzbach |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250100427
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| Publikation (Nr.) |
 EGU/EGU2014-16390.pdf |
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| Zusammenfassung |
| Accurately quantifying methane emissions from permafrost tundra landscapes into the
atmosphere is a major concern of the global climate modeling community. A better,
data-driven understanding of the drivers of soil-atmosphere CH4 fluxes could help constrain
the global methane balance, offer predictions in response to global climate change, and
advance understanding of these regions’ soil biogeochemistry and landscape ecology.
Previous research at our Lena River Delta research site (72° N, 126° E) has found relatively
low methane emissions (~18-30 mg m2d1) in the polygonal tundra of the delta’s Holocene
river terrace (Sachs et al., 2008; Wille et al., 2008). In fall 2013 we compare methane
emissions from this landscape type to the adjacent active river floodplain, a sandy, Equisetum
– Salix –Alopecurus alpinus community ecosystem. This landscape has backswamp regions
with higher organic matter accumulation though is generally dominated by soils with
high sand contents, low organic matter content, and lower water tables than the
Holocene terrace (Boike et al., 2013). The wet parts of a similar landscape unit in the
Indigirka lowlands (71° N, 147° E) have been demonstrated to have greater methane
emissions which were in part attributed to the annual deposition of nutrients via
flooding, increased primary productivity and associated root exudates, and higher soil
temperatures.
The results presented in this study compare methane fluxes derived from the closed
chamber technique from the two landscape units. In addition to descriptions of the inundation
height and vegetation cover, we examine soil chemical and physical characteristics to
test how these factors help control CH4 fluxes. We find, for example, relatively
high concentrations of dissolved organic carbon at sites with relatively high CH4
production.
As the modern floodplain landscape type covers 40% of the soil-covered area of the
Lena River Delta and is analogous to similar regions across the Arctic, increased
mechanistic understanding of its methane fluxes will provide valuable insights into
the functioning of the terrestrial-fluvial interface. Similarly, the Holocene river
terrace is representative of 22% of the Lena River Delta, and as the subject of a
longer-term measurement campaign offers the opportunity to contextualize this year’s
findings within a spectrum of multi-annual climate conditions. The work presented
here anticipates upcoming campaigns where the eddy covariance method will be
used to measure near continuous flux estimates from these landscapes in order to
significantly constrain methane flux estimates from lowland portions of the terrestrial
Arctic.
Works Cited
Boike, J., et al. (2003) Baseline characteristics of climate, permafrost and land cover from
a new permafrost observatory in the Lena River Delta, Siberia (1998–2011), Biogeosciences,
10(3), 2105–2128.
Sachs, T., et al (2008) Environmental controls on ecosystem-scale CH4 emission from
polygonal tundra in the Lena River Delta, Siberia, J Geophys Res, 113, G00A03.
Wille, C., et al. (2008) Methane emission from Siberian arctic polygonal tundra: eddy
covariance measurements and modeling, Glob. Change Biol., 14(6), 1395–1408. |
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