Century-scale time since permafrost thaw affects temperature sensitivity of net methane production in thermokarst-lake and talik sediments.

Autor: Heslop JK; Water and Environmental Research Center, University of Alaska, Fairbanks, USA. Electronic address: joannekheslop@gmail.com., Walter Anthony KM; Water and Environmental Research Center, University of Alaska, Fairbanks, USA., Grosse G; Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Potsdam, Germany; Institute of Earth and Environmental Sciences, University of Potsdam, Germany., Liebner S; GFZ German Research Centre for Geosciences, Section 3.7 Geomicrobiology, Helmholtz Centre Potsdam, Potsdam, Germany; University of Potsdam, Institute of Biochemistry and Biology, Germany., Winkel M; Water and Environmental Research Center, University of Alaska, Fairbanks, USA; GFZ German Research Centre for Geosciences, Section 3.7 Geomicrobiology, Helmholtz Centre Potsdam, Potsdam, Germany.
Jazyk: angličtina
Zdroj: The Science of the total environment [Sci Total Environ] 2019 Nov 15; Vol. 691, pp. 124-134. Date of Electronic Publication: 2019 Jul 02.
DOI: 10.1016/j.scitotenv.2019.06.402
Abstrakt: Permafrost thaw subjects previously frozen soil organic carbon (SOC) to microbial degradation to the greenhouse gases carbon dioxide (CO 2 ) and methane (CH 4 ). Emission of these gases constitutes a positive feedback to climate warming. Among numerous uncertainties in estimating the strength of this permafrost carbon feedback (PCF), two are: (i) how mineralization of permafrost SOC thawed in saturated anaerobic conditions responds to changes in temperature and (ii) how microbial communities and temperature sensitivities change over time since thaw. To address these uncertainties, we utilized a thermokarst-lake sediment core as a natural chronosequence where SOC thawed and incubated in situ under saturated anaerobic conditions for up to 400 years following permafrost thaw. Initial microbial communities were characterized, and sediments were anaerobically incubated in the lab at four temperatures (0 °C, 3 °C, 10 °C, and 25 °C) bracketing those observed in the lake's talik. Net CH 4 production in freshly-thawed sediments near the downward-expanding thaw boundary at the base of the talik were most sensitive to warming at the lower incubation temperatures (0 °C to 3 °C), while the overlying sediments which had been thawed for centuries had initial low abundant methanogenic communities (< 0.02%) and did not experience statistically significant increases in net CH 4 production potentials until higher incubation temperatures (10 °C to 25 °C). We propose these observed differences in temperature sensitivities are due to differences in SOM quality and functional microbial community composition that evolve over time; however further research is necessary to better constrain the roles of these factors in determining temperature controls on anaerobic C mineralization.
(Copyright © 2019. Published by Elsevier B.V.)
Databáze: MEDLINE
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