Greenhouse gas production and lipid biomarker distribution in Yedoma and Alas thermokarst lake sediments in Eastern Siberia

• Published in: Global Change Biology
• Main Authors: Jongejans, Loeka L., Liebner, Susanne, Knoblauch, Christian, Mangelsdorf, Kai, Ulrich, Mathias, Grosse, Guido, Tanski, George, Fedorov, Alexander N., Konstantinov, Pavel Ya, Windirsch, Torben, Wiedmann, Julia, Strauss, Jens
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: anaerobic; greenhouse gases; incubation experiments; lipid biomarkers; organic matter degradation; permafrost thaw; talik; Yakutia; /dk/atira/pure/sustainabledevelopmentgoals/climate_action; name=SDG 13 - Climate Action; /dk/atira/pure/sustainabledevelopmentgoals/life_below_water; name=SDG 14 - Life Below Water; Arctic; Talik; Ice; permafrost; Thermokarst; Siberia
• Online Access: https://research.vu.nl/en/publications/1a25e646-c243-46c4-9395-6796fe6dda97; https://doi.org/10.1111/gcb.15566; https://hdl.handle.net/1871.1/1a25e646-c243-46c4-9395-6796fe6dda97; http://www.scopus.com/inward/record.url?scp=85103168975&partnerID=8YFLogxK; http://www.scopus.com/inward/citedby.url?scp=85103168975&partnerID=8YFLogxK

Permafrost thaw leads to thermokarst lake formation and talik growth tens of meters deep, enabling microbial decomposition of formerly frozen organic matter (OM). We analyzed two 17-m-long thermokarst lake sediment cores taken in Central Yakutia, Russia. One core was from an Alas lake in a Holocene thermokarst basin that underwent multiple lake generations, and the second core from a young Yedoma upland lake (formed ~70 years ago) whose sediments have thawed for the first time since deposition. This comparison provides a glance into OM fate in thawing Yedoma deposits. We analyzed total organic carbon (TOC) and dissolved organic carbon (DOC) content, n-alkane concentrations, and bacterial and archaeal membrane markers. Furthermore, we conducted 1-year-long incubations (4°C, dark) and measured anaerobic carbon dioxide (CO 2 ) and methane (CH 4 ) production. The sediments from both cores contained little TOC (0.7 ± 0.4 wt%), but DOC values were relatively high, with the highest values in the frozen Yedoma lake sediments (1620 mg L −1 ). Cumulative greenhouse gas (GHG) production after 1 year was highest in the Yedoma lake sediments (226 ± 212 µg CO 2 -C g −1 dw, 28 ± 36 µg CH 4 -C g −1 dw) and 3 and 1.5 times lower in the Alas lake sediments, respectively (75 ± 76 µg CO 2 -C g −1 dw, 19 ± 29 µg CH 4 -C g −1 dw). The highest CO 2 production in the frozen Yedoma lake sediments likely results from decomposition of readily bioavailable OM, while highest CH 4 production in the non-frozen top sediments of this core suggests that methanogenic communities established upon thaw. The lower GHG production in the non-frozen Alas lake sediments resulted from advanced OM decomposition during Holocene talik development. Furthermore, we found that drivers of CO 2 and CH 4 production differ following thaw. Our results suggest that GHG production from TOC-poor mineral deposits, which are widespread throughout the Arctic, can be substantial. Therefore, our novel data are relevant for vast ice-rich permafrost deposits vulnerable to ...