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Thaw slumps can lead to considerable carbon loss in permafrost regions, while the loss of components from two major origins, i.e., microbial and plant-derived carbon, during this process remains poorly understood. Here, we provide direct evidence that microbial necromass carbon is a major component of lost carbon in a retrogressive permafrost thaw slump by analyzing soil organic carbon (SOC), biomarkers (amino sugars and lignin phenols), and soil environmental variables in a typical permafrost thaw slump in the Tibetan Plateau. The retrogressive thaw slump led to a similar to 61% decrease in SOC and a similar to 25% SOC stock loss. As evident in the levels of amino sugars (average of 55.92 +/- 18.79 mg g-1 of organic carbon, OC) and lignin phenols (average of 15.00 +/- 8.05 mg g-1 OC), microbial-derived carbon (microbial necromass carbon) was the major component of the SOC loss, accounting for similar to 54% of the SOC loss in the permafrost thaw slump. The variation of amino sugars was mainly related to the changes in soil moisture, pH, and plant input, while changes in lignin phenols were mainly related to the changes in soil moisture and soil bulk density.

来源平台：ENVIRONMENTAL SCIENCE & TECHNOLOGY