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| Titel |
Allocation of atmospheric CO2 into labile sub-surface carbon pools: a stable isotope labelling approach in a tundra wetland |
| VerfasserIn |
Norman Rüggen, Christian Knoblauch, Eva-Maria Pfeiffer |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250101770
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| Publikation (Nr.) |
 EGU/EGU2015-1000.pdf |
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| Zusammenfassung |
| Greenhouse gas emissions from permafrost-affected wetlands are intensively studied due to
their important role in the global carbon cycle. There are concerns of increasing methane and
carbon dioxide fluxes from tundra wetlands due to permafrost degradation and hydrology
changes in a warming Arctic. Understanding the sub-surface carbon pool interactions will
improve the prediction on how trace gas fluxes from these ecosystems will respond to
changing environmental conditions.
Partitioning the sources of greenhouse gas fluxes will help to evaluate the quantitative role
of recently produced plant photosynthates. Furthermore, partitioning allows separating
respiration of long-term stored organic matter and freshly produced plant products. This
knowledge is crucial for understanding the response of greenhouse gas fluxes in such
wetlands to environmental changes.
An in situ 13CO2 pulse-labelling experiment has been conducted in the northeast Siberian
tundra (Samoylov island, Lena river delta) in August 2013 to quantify interactions
among sub-surface carbon pools (DIC, DOC, CH4) in three depths (6, 16 and 36 cm)
of the active layer. The experimental site was a low-centred polygon centre in a
polygonal tundra landscape, with a sedge-moss (Carex-Scorpidium) plant association.
The water table was at the soils’ surface and the permafrost table in a depth of 50
cm.
After the system has been 13CO2 pulse labelled, all three studied subsurface carbon pools
(CH4, DIC and DOC) were clearly 13C-enriched, which accounts for atmospheric C
incorporated into these pools. One day after the labelling, in 6 cm depth 1.5 percent of DIC
and 0.1 percent of CH4were replaced by label C, which then steadily declined over a ten days
period. The label C content of DOC increased gradually over the same period. In 16
cm depth, the label C increased gradually after labelling in both DIC and CH4.
Label C was found in DIC and CH4 even in a depth of 36 cm, although in less
pronounced concentrations. Carex material, exposed to the label, also substantially
incorporated the label. Deduced from the results, we will present carbon exchange fluxes
among sub-surface DIC, DOC and CH4 in a sedge-moss covered polygon-centre. |
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