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

Abstract

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 sedimentsThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Geochemistry and Weathering Indices of Yedoma and Alas Deposits beneath Thermokarst Lakes in Central Yakutia

“…Relatively few OM was deposited, which could then be decomposed comparatively quickly. Despite the low OC content of the Yukechi Yedoma IC sediments, Jongejans et al (2021a) found substantial greenhouse gas production from sediments upon thawing. Their findings showed that the OM quality and turnover history are the main driver for GHG production (Jongejans et al, 2021a).…”

“…Strauss et al (2017) calculated an amount of 398 Gt OC for the total circum-Arctic Yedoma domain (1.4 million km 2 , including thermokarst lakes and basins). However, recent carbon inventory studies of Central Yakutian Yedoma deposits show significantly lower levels of OC (Ø 0.4-0.7 wt%; Windirsch et al, 2020;Jongejans et al, 2021a).…”

Temperature sensitivity of anaerobic methane oxidation versus methanogenesis in paddy soil: Implications for the CH4 balance under global warming

“…The modern global net emission to the atmosphere is ~580 Tg CH 4 year −1 (He et al, 2020) and increasing by ~5 Tg CH 4 year −1 (Saunois et al, 2016). CH 4 is produced in the last step of anaerobic organic carbon reduction (methanogenesis; Megonigal et al, 2004) by various methanogenic archaea (including hydrogenotrophs, formatotrophs, acetotrophs, methylotrophs, and alcoholotrophs; Bridgham et al, 2013;Chen et al, 2013;Jongejans et al, 2021;McNicol et al, 2020;Serrano-Silva et al, 2014). In turn, CH 4 itself can serve as a carbon and energy source for specialized aerobic and anaerobic microorganisms (methanotrophs) in sediments and soils (see Knittel & Boetius, 2009;Serrano-Silva et al, 2014 for reviews).…”

14,000-year Carbon Accumulation Dynamics in a Siberian Lake Reveal Catchment and Lake Productivity Changes

“…A significant portion of the Lake Malaya Chabyda sediment core is classified as organic sediment, which is predicted to lose comparatively high percentages of their OC upon potential exposure. Jongejans et al (2021) found that although the OC content of the Yukechi Yedoma ice complex sediments was relatively low, there was substantial greenhouse gas release upon thawing. These findings point to OM quality and decomposition history and more important drivers of greenhouse gas release than OM content alone (Jongejans et al, 2021).…”