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Abstract

Summary

Thawing terrestrial permafrost has recently become a source of atmospheric methane (CH4). Concurrently, subsea permafrost is thawing at much faster rates, yet little is known about the consequences due to its inaccessibility. Elevated CH4 concentrations have been recorded in the Arctic shelf seas underlain by subsea permafrost, but the spatial extent of these emissions is highly variable due to the frequent occurrence of storms ventilating CH4 to the atmosphere. In this study, an integrated aerobic CH4 signal was assessed from geohopanoids (diploptene, hop-17(21)-ene, neohop-13(18)-ene) in surface sediments across the Laptev Sea. Furthermore, 16s-rRNA was used to investigate the potential hopanoid producers present in the sediments. Depleted d13C-C30 hopenes was observed across all sediments, indicative of aerobic methanotrophy, particularly in the outer Laptev Sea. However, in the vicinity of the Lena River delta high concentrations of geohopanoids more enriched in 13C suggests a mixed signal not solely related to aerobic methanotrophs. This was further assessed from 16s-rRNA by the abundance of non-methanotrophic hopanoid producers. Taken together, this study displays the possibility to assess long term CH4 aerobic methane activity in a region of highly variable CH4 concentrations through geohopanoids. However, a thorough system knowledge of different hopanoid producers is suggested.

© EAGE Publications BV
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2025-09-07
2026-02-11

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Geospatial Extent of Aerobic Methane Activity in the Laptev Sea Assessed through Geohopanoids in Surface Sediments
Conference Proceedings 2025, 1 (2025); https://doi.org/10.3997/2214-4609.202533199
/content/papers/10.3997/2214-4609.202533199
/content/papers/10.3997/2214-4609.202533199
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