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An active layer detachment slide (ALDS) in the interior portion of the Qinghai-Tibet Plateau (QTP) was investigated within 2 days of its formation on September 21, 2018. The ALDS developed on a relatively gentle slope (4.8 to 9 ) at an elevation of 4,850 m above sea level (asl) and was about 145 m long and 45 m wide, with a headscarp 2.2-2.5 m high. Analyses of meteorological data and soil temperatures indicated that it was probably triggered by a record thaw depth which intersected a layer with high ice content at the base of the active layer and in the top of the permafrost. Based on the time window, the minimum downslope velocity of the main slide mass was about 20 m/h which is higher than previously reported values. The ALDS ran into the embankment of the Qinghai-Tibet Railway (QTR) but did not damage the railbed. However, extensive rehabilitation of the slope was needed subsequent to the failure to clear the slide mass and as minor headscarp recession and thaw settlement continued on the slope. In this work, we describe this feature and the most likely mechanisms of development.

Permafrost thaw can bring negative consequences in terms of ecosystems, resulting in permafrost collapse, waterlogging, thermokarst lake development, and species composition changes. Little is known about how permafrost thaw influences microbial community shifts and their activities. Here, we show that the dominant archaeal community shifts from Methanomicrobiales to Methanosarcinales in response to the permafrost thaw, and the increase in methane emission is found to be associated with the methanogenic archaea, which rapidly bloom with nearly tenfold increase in total number. The mcrA gene clone libraries analyses indicate that Methanocellales/Rice Cluster I was predominant both in the original permafrost and in the thawed permafrost. However, only species belonging to Methanosarcinales showed higher transcriptional activities in the thawed permafrost, indicating a shift of methanogens from hydrogenotrophic to partly acetoclastic methane-generating metabolic processes. In addition, data also show the soil texture and features change as a result of microbial reproduction and activity induced by this permafrost thaw. Those data indicate that microbial ecology under warming permafrost has potential impacts on ecosystem and methane emissions.

A Gram-reaction-negative bacterial strain, designated F4 T , was isolated from a subsurface sediment core of Qiangtang Basin permafrost in China. Cells were catalase-and oxidasepositive and rods. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain F4T was a member of the family Hyphomicrobiaceae and was most closely related to members of the genera Pelagibacterium, Vasilyevaea and Devosia with 93.8-96.2 % sequence similarities. The major cellular fatty acids were C 16 : 0 , C 18 : 0 , 11-methyl C 18 : 1 v7c, C 19 : 0 cyclo v8c and summed feature 8 (C 18 : 1 v7c and/or C 18 : 1 v6c). The major respiratory quinone was Q-10 and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and two unknown glycolipids. The DNA G+C content was 60.7 mol%. Based on the phenotypic, phylogenetic and genotypic data, strain F4 T is considered to represent a novel species of a new genus in the family Hyphomicrobiaceae, for which the name Youhaiella tibetensis gen. nov., sp. nov. is proposed. The type strain is F4 T (5CGMCC 1.12719 T 5JCM 19854 T ).