Organic matter composition and greenhouse gas production of thawing subsea permafrost in the Laptev Sea

Subsea permafrost represents a large carbon pool that might be or become a significant greenhouse gas source. Scarcity of observational data causes large uncertainties. We here use five 21-56 m long subsea permafrost cores from the Laptev Sea to constrain organic carbon (OC) storage and sources, deg...

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Bibliographic Details
Published in:Nature Communications
Main Authors: Wild, Birgit, Shakhova, Natalia, Dudarev, Oleg, Ruban, Alexey, Kosmach, Denis, Tumskoy, Vladimir, Tesi, Tommaso, Grimm, Hanna, Nybom, Inna, Matsubara, Felipe, Alexanderson, Helena, Jakobsson, Martin, Mazurov, Alexey, Semiletov, Igor, Gustafsson, Örjan
Format: Text
Language:English
Published: Nature Publishing Group UK 2022
Subjects:
Article
Laptev Sea
laptev
Ocean acidification
permafrost
Tundra
Online Access:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9420143/
http://www.ncbi.nlm.nih.gov/pubmed/36030269
https://doi.org/10.1038/s41467-022-32696-0
Description
Summary:Subsea permafrost represents a large carbon pool that might be or become a significant greenhouse gas source. Scarcity of observational data causes large uncertainties. We here use five 21-56 m long subsea permafrost cores from the Laptev Sea to constrain organic carbon (OC) storage and sources, degradation state and potential greenhouse gas production upon thaw. Grain sizes, optically-stimulated luminescence and biomarkers suggest deposition of aeolian silt and fluvial sand over 160 000 years, with dominant fluvial/alluvial deposition of forest- and tundra-derived organic matter. We estimate an annual thaw rate of 1.3 ± 0.6 kg OC m(−2) in subsea permafrost in the area, nine-fold exceeding organic carbon thaw rates for terrestrial permafrost. During 20-month incubations, CH(4) and CO(2) production averaged 1.7 nmol and 2.4 µmol g(−1) OC d(−1), providing a baseline to assess the contribution of subsea permafrost to the high CH(4) fluxes and strong ocean acidification observed in the region.

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