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Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 10, issue 6 | Copyright

Special issue: Interactions between the land and sea in the Lena Delta...

Biogeosciences, 10, 3507-3524, 2013
https://doi.org/10.5194/bg-10-3507-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 03 Jun 2013

Research article | 03 Jun 2013

Organic carbon and total nitrogen stocks in soils of the Lena River Delta

S. Zubrzycki1, L. Kutzbach1, G. Grosse2, A. Desyatkin3, and E.-M. Pfeiffer1 S. Zubrzycki et al.
  • 1Institute of Soil Science, KlimaCampus, University of Hamburg, Hamburg, Germany
  • 2Geophysical Institute, University of Alaska Fairbanks, Fairbanks, Alaska, USA
  • 3Institute for Biological Problems of Cryolithozone, SB RAS, Yakutsk, Russia

Abstract. The Lena River Delta, which is the largest delta in the Arctic, extends over an area of 32 000 km2 and likely holds more than half of the entire soil organic carbon (SOC) mass stored in the seven major deltas in the northern permafrost regions. The geomorphic units of the Lena River Delta which were formed by true deltaic sedimentation processes are a Holocene river terrace and the active floodplains. Their mean SOC stocks for the upper 1 m of soils were estimated at 29 kg m−2 ± 10 kg m−2 and at 14 kg m−2 ± 7 kg m−2, respectively. For the depth of 1 m, the total SOC pool of the Holocene river terrace was estimated at 121 Tg ± 43 Tg, and the SOC pool of the active floodplains was estimated at 120 Tg ± 66 Tg. The mass of SOC stored within the observed seasonally thawed active layer was estimated at about 127 Tg assuming an average maximum active layer depth of 50 cm. The SOC mass which is stored in the perennially frozen ground at the increment 50–100 cm soil depth, which is currently excluded from intense biogeochemical exchange with the atmosphere, was estimated at 113 Tg. The mean nitrogen (N) stocks for the upper 1 m of soils were estimated at 1.2 kg m−2 ± 0.4 kg m−2 for the Holocene river terrace and at 0.9 kg m−2 ± 0.4 kg m−2 for the active floodplain levels, respectively. For the depth of 1 m, the total N pool of the river terrace was estimated at 4.8 Tg ± 1.5 Tg, and the total N pool of the floodplains was estimated at 7.7 Tg ± 3.6 Tg. Considering the projections for deepening of the seasonally thawed active layer up to 120 cm in the Lena River Delta region within the 21st century, these large carbon and nitrogen stocks could become increasingly available for decomposition and mineralization processes.

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