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Biogeosciences An interactive open-access journal of the European Geosciences Union
doi:10.5194/bg-2017-89
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
17 Mar 2017
Review status
This discussion paper is under review for the journal Biogeosciences (BG).
Substrate potential of Eemian to Holocene permafrost organic matter for future microbial greenhouse gas production
Janina G. Stapel1, Georg Schwamborn2, Lutz Schirrmeister2, Brian Horsfield1, and Kai Mangelsdorf1 1GFZ, German Research Centre for Geoscience, Helmholtz Centre Potsdam, Organic Geochemistry, Telegrafenberg, 14473 Potsdam, Germany
2Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Research Unit Potsdam, Department of Periglacial Research, Telegrafenberg, A43, 14473 Potsdam, Germany
Abstract. Multiple permafrost cores from Bol'shoy Lyakhovsky Island in NE Siberia comprising deposits from Eemian to modern time are investigated to evaluate the stored potential of the freeze-locked organic matter (OM) to serve as substrate for the production of microbial greenhouse gases from thawing permafrost deposits. Deposits from Late Pleistocene glacial periods (comprising MIS 3 and MIS 4) possess an increased aliphatic character and a higher amount of potential substrates, and therefore higher OM quality in terms of biodegradation compared to interglacial deposits from the Eemian (MIS 5e) as well as from the Holocene (MIS 1). To assess the potential of the individual permafrost deposits to provide substrates for microbially induced greenhouse gas generation, concentrations of free and bound acetate as an excellent substrate for methanogenesis are used. The highest free (in pore water and segregated ice) and bound (bound to the organic matrix) acetate-substrate pools of the permafrost deposits are observed within the interstadial MIS 3 and stadial MIS 4 period deposits. In contrast, deposits from the last interglacial MIS 5e show only poor substrate pools. The Holocene deposits reveal a significant bound-acetate pool, representing at least a future substrate potential upon release during OM degradation. Biomarkers for past microbial communities (branched and isoprenoid GDGTs) show also highest abundance of past microbial communities during the MIS 3 and MIS 4 deposits, which indicates higher OM quality with respect to microbial degradation during time of deposition. On a broader perspective, Arctic warming will increase permafrost thaw and favour substrate availability from freeze-locked older permafrost deposits. Therefore, especially those deposits from MIS 3 and MIS 4 show a high potential for providing substrates relevant for methanogenesis.

Citation: Stapel, J. G., Schwamborn, G., Schirrmeister, L., Horsfield, B., and Mangelsdorf, K.: Substrate potential of Eemian to Holocene permafrost organic matter for future microbial greenhouse gas production, Biogeosciences Discuss., doi:10.5194/bg-2017-89, in review, 2017.
Janina G. Stapel et al.
Janina G. Stapel et al.
Janina G. Stapel et al.

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Short summary
Climate warming in the Arctic results in thawing of permafrost deposits with different bio- and geochemical properties reflecting changing past climatic and environmental conditions during the time of accumulation. Permafrost deposits from the last glacial period, especially from the MIS 3, possess the highest potential to provide organic substrates for future microbial greenhouse gas production and therefore indicate to have the strongest carbon-climate feedback potential.
Climate warming in the Arctic results in thawing of permafrost deposits with different bio- and...
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