Brief Communication: The reliability of gas extraction techniques for analysing CH4 and N2O compositions in gas trapped in permafrost ice wedges

• Published in: The Cryosphere
• Main Authors: Yang, Ji-Woong, Ahn, Jinho, Iwahana, Go, Han, Sangyoung, Kim, Kyungmin, Fedorov, Alexander, A.
• Other Authors: School of Earth and Environmental Sciences Seoul (SEES), Seoul National University Seoul (SNU), Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), International Arctic Research Center (IARC), University of Alaska Fairbanks (UAF), Tohoku University Sendai, North-Eastern Federal University, Melnikov Permafrost Institute, Siberian Branch of the Russian Academy of Sciences (SB RAS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Ice; permafrost; The Cryosphere; wedge*; Alaska; Siberia
• Online Access: https://hal.science/hal-02971262; https://hal.science/hal-02971262/document; https://hal.science/hal-02971262/file/tc-14-1311-2020.pdf; https://doi.org/10.5194/tc-14-1311-2020

International audience Methane (CH 4) and nitrous oxide (N 2 O) compositions in ground ice may provide information on their production mechanisms in permafrost. However, existing gas extraction methods have not been well tested. We tested conventional wet and dry gas extraction methods using ice wedges from Alaska and Siberia, finding that both methods can extract gas from the easily extractable parts of the ice (e.g. gas bubbles) and yield similar results for CH 4 and N 2 O mixing ratios. We also found insignificant effects of microbial activity during wet extraction. However, both techniques were unable to fully extract gas from the ground ice, presumably because gas molecules adsorbed onto or enclosed in soil aggregates are not easily extractable. Estimation of gas production in a subfreezing environment of permafrost should consider such incomplete gas extraction.