Origin of CO 2 , CH 4 , and N 2 O trapped in ice wedges in central Yakutia and their relationship

• Published in: Permafrost and Periglacial Processes
• Main Authors: Yang, Ji‐Woong, Ahn, Jinho, Iwahana, Go, Ko, Nayeon, Kim, Ji‐Hoon, Kim, Kyungmin, Fedorov, Alexander, Han, Sangyoung
• Other Authors: National Research Foundation of Korea
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2022
• Subjects: Ice; permafrost; Permafrost and Periglacial Processes; wedge*; Yakutia; Siberia
• Online Access: http://dx.doi.org/10.1002/ppp.2176; https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.2176; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/ppp.2176

Abstract Permafrost thawing as a result of global warming is expected to foster the biological remineralization of intact organic carbon and nitrogen and release greenhouse gas (GHG) into the atmosphere, which will have positive feedback for future global warming. However, GHG budgets and their controls in permafrost ground ice are not yet fully understood. This study aims to better understand the control mechanisms of GHG in ground ice by using new gas and chemistry data. In this study, we present new data on carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O) mixing ratios in three different ice wedges, Churapcha, Syrdakh, and Cyuie, located in central Yakutia, Siberia. The GHG mixing ratios in the studied ice wedges range from 0.0% to 13.8% CO 2 , 1.3–91.2 ppm CH 4 , and 0% and 0–1414 N 2 O. In particular, all three ice wedges demonstrate that ice‐wedge samples enriched in CH 4 were depleted in N 2 O mixing ratios and vice versa. N 2 –O 2 –Ar compositions indicate that the studied ice wedges were most likely formed by dry snow or hoarfrost, not by freezing of snow meltwater, and the O 2 ‐consuming biological metabolism was active. Most of the observed GHG mixing ratios cannot be explained without microbial metabolism. The inhibitory impact of denitrification products of nitrate (including N 2 O) could be an important control of the ice‐wedge CH 4 mixing ratio.