National Tomsk Research Polytechnic University, 30 Prospect Lenina, Tomsk, Alaska 634050, Russia.
International Arctic Research Center, University of Alaska Fairbanks, Akasofu Building, Fairbanks, Alaska 99775-7320, USA.
Nat Commun. 2017 Jun 22;8:15872. doi: 10.1038/ncomms15872.
The rates of subsea permafrost degradation and occurrence of gas-migration pathways are key factors controlling the East Siberian Arctic Shelf (ESAS) methane (CH) emissions, yet these factors still require assessment. It is thought that after inundation, permafrost-degradation rates would decrease over time and submerged thaw-lake taliks would freeze; therefore, no CH release would occur for millennia. Here we present results of the first comprehensive scientific re-drilling to show that subsea permafrost in the near-shore zone of the ESAS has a downward movement of the ice-bonded permafrost table of ∼14 cm year over the past 31-32 years. Our data reveal polygonal thermokarst patterns on the seafloor and gas-migration associated with submerged taliks, ice scouring and pockmarks. Knowing the rate and mechanisms of subsea permafrost degradation is a prerequisite to meaningful predictions of near-future CH release in the Arctic.
海底永久冻土退化和天然气迁移途径的出现是控制东西伯利亚北极大陆架（ESAS）甲烷（CH）排放的关键因素，但这些因素仍需要评估。据认为，在淹没后，永久冻土退化的速度会随着时间的推移而降低，而淹没的融湖层间冰会冻结；因此，数千年来不会有 CH 释放。在这里，我们介绍了首次全面科学重新钻探的结果，表明 ESAS 近岸区的海底永久冻土在过去 31-32 年中，冰结合的永久冻土表向下移动了约 14cm 年。我们的数据揭示了海底多边形热喀斯特图案以及与淹没的层间冰、冰侵蚀和麻坑有关的气体迁移。了解海底永久冻土退化的速度和机制是对北极地区近期 CH 释放进行有意义预测的前提。
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