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Biogeosciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/bg-2018-225
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
14 May 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Biogeosciences (BG).
Greenhouse gas production in degrading ice-rich permafrost deposits in northeast Siberia
Josefine Walz1,2, Christian Knoblauch1,2, Ronja Tigges1, Thomas Opel3,4, Lutz Schirrmeister4, and Eva-Maria Pfeiffer1,2 1Institute of Soil Science, Universität Hamburg, Hamburg, 20146, Germany
2Center for Earth System Research and Sustainability, Universität Hamburg, Hamburg, 20146, Germany
3Permafrost Laboratory, Department of Geography, University of Sussex, Brighton, BN1 9RH, UK
4Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Periglacial Research Section, 14473 Potsdam, Germany
Abstract. Permafrost deposits have been a sink for atmospheric carbon for millennia. Thaw-erosional processes, however, can lead to rapid degradation of ice-rich permafrost and the release of substantial amounts of organic carbon (OC). The amount of the OC stored in these deposits and their potential to be microbially decomposed to the greenhouse gases carbon dioxide (CO2) and methane (CH4) depends on climatic and environmental conditions during deposition and the decomposition history before incorporation into the permafrost. Here, we examine potential greenhouse gas production in degrading ice-rich permafrost deposits from three locations in the northeast Siberian Laptev Sea region. The deposits span a period of about 55 kyr and include deposits from the last glacial and Holocene interglacial periods. Samples from all three locations were aerobically and anaerobically incubated for 134 days at 4 °C. Greenhouse gas production was generally higher in glacial than Holocene deposits. In permafrost deposits from the Holocene and the late glacial transition, only 0.1–4.0 % of the initially available OC could be decomposed to CO2, while 0.2–6.1 % could be decomposed in glacial deposits. Within the glacial deposits from the Kargin interstadial period (Marine Isotope Stage 3), local depositional environments, especially soil moisture, also affected the preservation of OC. Sediments deposited under wet conditions contained more labile OC and thus produced more greenhouse gases than sediments deposited under drier conditions. To assess the long-term production potentials, deposits from two locations were incubated for a total of 785 days. However, more than 50 % of the aerobically produced and more than 80 % of anaerobically produced CO2 after 785 days of incubation were already produced within the first 134 days, highlighting the quantitative importance of the slowly decomposing OC pool in permafrost. CH4 production was generally observed in active layer samples but only sporadically in permafrost samples and was several orders of magnitude smaller than CO2 production.
Citation: Walz, J., Knoblauch, C., Tigges, R., Opel, T., Schirrmeister, L., and Pfeiffer, E.-M.: Greenhouse gas production in degrading ice-rich permafrost deposits in northeast Siberia, Biogeosciences Discuss., https://doi.org/10.5194/bg-2018-225, in review, 2018.
Josefine Walz et al.
Josefine Walz et al.
Josefine Walz et al.

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Short summary
We investigate potential CO2 and CH4 production in degrading ice-rich permafrost in northeast Siberia deposited under different climatic conditions. With laboratory incubations, it could be shown that Late Pleistocene Yedoma deposits generally produced more CO2 than Holocene deposits. Thus, OM decomposability needs to be interpreted against the paleo-environmental background. However, OM decomposability cannot be generalized solely based on the stratigraphic position.
We investigate potential CO2 and CH4 production in degrading ice-rich permafrost in northeast...
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