Department of Environmental Science, Stockholm University, 11418, Stockholm, Sweden.
Bolin Centre for Climate Research, Stockholm University, 11418, Stockholm, Sweden.
Nat Commun. 2022 Aug 27;13(1):5057. doi: 10.1038/s41467-022-32696-0.
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 in subsea permafrost in the area, nine-fold exceeding organic carbon thaw rates for terrestrial permafrost. During 20-month incubations, CH and CO production averaged 1.7 nmol and 2.4 µmol g OC d, providing a baseline to assess the contribution of subsea permafrost to the high CH fluxes and strong ocean acidification observed in the region.
海底永冻层代表了一个巨大的碳库，它可能成为或已经成为重要的温室气体源。由于观测数据的缺乏，存在着很大的不确定性。我们在这里使用来自拉普捷夫海的 5 个 21-56 米长的海底永冻土岩芯，以限制有机碳（OC）的储存和来源、降解状态以及解冻时潜在的温室气体产生。颗粒大小、光激发发光和生物标志物表明，在 16 万年的时间里，有风尘淤泥和河流砂的沉积，主要是森林和苔原来源的有机物质的河流/冲积物沉积。我们估计该地区海底永冻土的年解冻率为 1.3 ± 0.6 kg OC m，是陆地永冻土中有机碳解冻率的九倍。在 20 个月的培养过程中，CH 和 CO 的产量平均为 1.7 nmol 和 2.4 µmol g OC d，为评估海底永冻土对该地区观察到的高 CH 通量和强烈海洋酸化的贡献提供了基线。
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