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Titel |
Soil Organic Carbon Stocks in Arctic Deltaic Sediments: Investigations in the Lena River Delta. |
VerfasserIn |
S. Zubrzycki, L. Kutzbach, A. Desyatkin, E.-M. Pfeiffer |
Konferenz |
EGU General Assembly 2012
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 14 (2012) |
Datensatznummer |
250067535
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Zusammenfassung |
The soil organic carbon stock (SSOC) of deltaic sediments in arctic permafrost regions is
known to be significant but is insufficiently investigated so far. Previous SSOC studies were
conducted mainly in the comparatively well studied Mackenzie River Delta (area:
13,000Â km2) in Canada. The few studies from other arctic delta regions report only the
gravimetric carbon (C) contents and are limited to the active layer depth at the time of
sampling.
Since C deposits in permafrost regions are likely to become a future C source,
more detailed investigations of the presently frozen likely carbon-rich sediment and
soil layers in other arctic delta regions are of importance. Our investigations were
performed on Samoylov Island in the southern-central part of the Lena River Delta
(32,000Â km2) which is the largest arctic delta and the fifth largest delta worldwide.
Samoylov Island is representative for the Lena River Delta’s first terrace and the active
floodplains.
Within this study a new portable Snow-Ice-Permafrost-Research-Establishment (SIPRE)
auger was used during a spring field session to obtain 1 m deep frozen soil cores (n = 37)
distributed over all known soil and vegetation units. These cores are analyzed for bulk
contents of nitrogen (N) and C, ice content and bulk density (BD) and to determine the SSOC
including the rarely investigated currently permanently frozen layers up to 1Â m depth on
Samoylov Island.
Our study provides evidence for high SSOC for a depth of 1Â m for the investigated
area ranging between 6 kg m2 and 54 kg m2. Considering the spatial extent of
different soil units on the two geomorphological units of Samoylov Island, the
area-weighted average SSOC were 31 kg m2 (n = 31) for the first terrace and
15 kg m2 (n = 6) for the active floodplain. For the correspondent soil units of
Turbels and Orthels in circumpolar permafrost regions, Tarnocai et al. 2009 reported
a mean SSOC of 27 kg m2 (min: 0.1 kg m2, max: 126 kg m2) for a depth of
1Â m.
For up-scaling over the soil-covered areas only, we excluded all water bodies from the
geomorphological units studied (first river terrace and the active floodplains) and additionally
corrected the extent of the first terrace’s land area by reducing it by the percentage of small
water ponds and cracks detected by high-resolution aerial photography for Samoylov Island.
We scaled the area-weighted SSOC averages estimated for the two geomorphological units of
Samoylov Island across the corrected total land areas of the Lena River Delta’s
first terrace (9,400Â km2) and the active floodplains (3,500Â km2) leading to total
organic soil carbon storage estimates for a depth of 1 m of 290 Tg C and 50 Tg C,
respectively.
References:
Tarnocai, C., Canadell, J.G., Schuur, E.A.G., Kuhry, P. Mazhitova, G. & Zimov, S., 2009.
Soil organic carbon pools in the northern circumpolar permafrost region. Global
Biogeochemical Cycles 23, GB2023: 11p. |
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