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| Titel |
Stable carbon isotopes as indicators for environmental change in palsa peats |
| VerfasserIn |
C. Alewell, R. Giesler, J. Klaminder, J. Leifeld, M. Rollog |
| 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. 7 ; Nr. 8, no. 7 (2011-07-08), S.1769-1778 |
| Datensatznummer |
250006041
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| Publikation (Nr.) |
 copernicus.org/bg-8-1769-2011.pdf |
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| Zusammenfassung |
Palsa peats are unique northern ecosystems formed under an arctic climate
and characterized by a high biodiversity and sensitive ecology. The
stability of the palsas are seriously threatened by climate warming which
will change the permafrost dynamic and induce a degradation of the mires.
We used stable carbon isotope depth profiles in two palsa mires of Northern
Sweden to track environmental change during the formation of the mires.
Soils dominated by aerobic degradation can be expected to have a clear
increase of carbon isotopes (δ13C) with depth, due to
preferential release of 12C during aerobic mineralization. In soils
with suppressed degradation due to anoxic conditions, stable carbon isotope
depth profiles are either more or less uniform indicating no or very low
degradation or depth profiles turn to lighter values due to an enrichment of
recalcitrant organic substances during anaerobic mineralisation which are
depleted in 13C.
The isotope depth profile of the peat in the water saturated depressions
(hollows) at the yet undisturbed mire Storflaket indicated very low to no
degradation but increased rates of anaerobic degradation at the Stordalen
site. The latter might be induced by degradation of the permafrost cores in
the uplifted areas (hummocks) and subsequent breaking and submerging of the
hummock peat into the hollows due to climate warming. Carbon isotope depth
profiles of hummocks indicated a turn from aerobic mineralisation to
anaerobic degradation at a peat depth between 4 and 25 cm. The age of these
turning points was 14C dated between 150 and 670 yr and could thus
not be caused by anthropogenically induced climate change. We found the
uplifting of the hummocks due to permafrost heave the most likely
explanation for our findings. We thus concluded that differences in carbon
isotope profiles of the hollows might point to the disturbance of the mires
due to climate warming or due to differences in hydrology. The
characteristic profiles of the hummocks are indicators for micro-geomorphic
change during permafrost up heaving. |
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