Methane Content in Ground Ice and Sediments of the Kara Sea Coast

Geosciences

DmitryA. Streletskiy¹  GlebE. Oblogov²  AlexanderA. Vasiliev²  IrinaD. Streletskaya³ 

[1] George Washington University, Department of Geography, Washington, DC 20052, USA;Institute of the Earth’s Cryosphere of Tyumen Scientific Center of Siberian Branch of Russian Academy of Sciences, 625000 Tyumen, Russia;Moscow State University, Faculty of Geography, Department of Cryolitology and Glaciology, 119991 Moscow, Russia;

关键词: ground ice;    permafrost;    methane;    Kara Sea;    Arctic;   

DOI  :  10.3390/geosciences8120434

来源: DOAJ

【 摘 要 】

Permafrost degradation of coastal and marine sediments of the Arctic Seas can result in large amounts of methane emitted to the atmosphere. The quantitative assessment of such emissions requires data on variability of methane content in various types of permafrost strata. To evaluate the methane concentrations in sediments and ground ice of the Kara Sea coast, samples were collected at a series of coastal exposures. Methane concentrations were determined for more than 400 samples taken from frozen sediments, ground ice and active layer. In frozen sediments, methane concentrations were lowest in sands and highest in marine clays. In ground ice, the highest concentrations above 500 ppmV and higher were found in massive tabular ground ice, with much lower methane concentrations in ground ice wedges. The mean isotopic composition of methane is −68.6‰ in permafrost and −63.6‰ in the active layer indicative of microbial genesis. The isotopic compositions of the active layer is enriched relative to permafrost due to microbial oxidation and become more depleted with depth. Ice-rich sediments of Kara Sea coasts, especially those with massive tabular ground ice, hold large amounts of methane making them potential sources of methane emissions under projected warming temperatures and increasing rates of coastal erosion.

【 授权许可】

Unknown