TY  - JOUR
A1  - Heslop, J. K.
A1  - Anthony, K. M. Walter
A1  - Grosse, Guido
A1  - Liebner, Susanne
A1  - Winkel, Matthias
T1  - Century-scale time since permafrost thaw affects temperature sensitivity of net methane production in thermokarst-lake and talik sediments
T2  - The science of the total environment : an international journal for scientific research into the environment and its relationship with man
N2  - Permafrost thaw subjects previously frozen soil organic carbon (SOC) to microbial degradation to the greenhouse gases carbon dioxide (CO2) and methane (CH4). 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 CH4 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 CH4 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.
KW  - Carbon
KW  - Lake sediments
KW  - Methane
KW  - Permafrost
KW  - Talik
KW  - Temperature sensitivity
Y1  - 2019
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/47836
SN  - 0048-9697
SN  - 1879-1026
VL  - 691
SP  - 124
EP  - 134
PB  - Elsevier
CY  - Amsterdam
ER  -