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| Titel |
Organic Carbon and Nitrogen Storages of Soils Overlying Yedoma Deposits in
the Lena River Delta |
| VerfasserIn |
Sebastian Zubrzycki, Lars Kutzbach, Aleksei Desiatkin, Eva-Maria Pfeiffer |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250126897
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| Publikation (Nr.) |
 EGU/EGU2016-6691.pdf |
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| Zusammenfassung |
| The Lena River Delta (LRD) is located in northeast Siberia and extends over a soil covered
area of around 21,500 km2. LRD likely stores more than half of the entire soil organic
carbon (SOC) mass stored in deltas affected by permafrost. LRD consists of several
geomorphic units. Recent studies showed that the spatially dominating Holocene units of the
LRD (61 % of the area) store around 240 Tg of SOC and 12 Tg of nitrogen (N) within the
first meter of ground. These units are a river terrace dominated by wet sedge polygons
and the active floodplains. About 50 % of these reported storages are located in
the perennially frozen ground below 50 cm depth and are excluded from intense
biogeochemical exchange with the atmosphere today. However, these storages are likely to
be mineralised in near future due to the projected temperature increases in this
region.
A substantial part of the LRD (1,712 km2) belongs to the so-called Yedoma
Region, which formed during the Late Pleistocene. This oldest unit of the LRD is
characterised by extensive plains incised by thermo-erosional valleys and large thermokarst
depressions. Such depressions are called Alases and cover around 20 % of the
area.
Yedoma deposits in the LDR are known to store high amounts of SOC. However, within
the LRD no detailed spatial studies on SOC and N in the soils overlying Yedoma and
thermokarst depressions were carried out so far.
We present here our “investigation in progress” on soils in these landscape units of the
LRD. Our first estimates, based on 69 pedons sampled in 2008, show that the mean SOC
stocks for the upper 30 cm of soils on both units were estimated at 13.0 kg m2 ±
4.8 kg m2 on the Yedoma surfaces and at 13.1 kg m2 ± 3.8 kg m2 in the Alases. The
stocks of N were estimated at 0.69 kg m2 ± 0.25 kg m2and at 0.70 kg m2 ±
0.18 kg m2 on the Yedoma surfaces and in the Alases, respectively.
The estimated SOC and N pools for the depth of 30 cm within the investigated part of the
LRD add to 20.9 Tg and 1.1 Tg, respectively. The Yedoma surfaces (1,313 km2)
store 17.1 ± 6.3 Tg SOC and 0.9 ± 0.3 Tg N, whereas the Alases (287 km2)
store 3.8 ± 1.1 Tg SOC and 0.2 ± 0.05 Tg N within the investigated depth of
30 cm.
Further analyses of the soil core material collected in 2013 will provide SOC and N pool
estimates for a depth of 100 cm including both, the seasonally active layer and the
perennially frozen ground. With continuing advanced analyses of an available digital
elevation model, slopes will be designated with their extents and inclinations since the planar
extents of slopes derived from satellite imagery do not correspond to the actual slope soil
surface area, which is vital for spatial SOC and N storage calculations as well as trace gas
release estimates. The actual soil surface area of slopes will be calculated prior to result
extrapolations. |
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