Thermokarst lake drainage halves the temperature sensitivity of CH4 release on the Qinghai-Tibet Plateau
Mei Mu, Cuicui Mu, Hebin Liu, Pengsi Lei, Yanqi Ge, Zhensong Zhou, Xiaoqing Peng, Tian Ma
Abstract
Abstract Thermokarst lakes as hot spots of methane (CH 4 ) release are crucial for predicting permafrost carbon feedback to global warming. These lakes are suffering from serious drainage events, however, the impacts of lake drainage on CH 4 release remain unclear. Here, synthesizing field drilling, incubation experiments, and carbon composition and microbial communities, we reveal the temperature sensitivities (Q 10 ) and drivers of CH 4 release from drainage-affected lakes on the Qinghai-Tibet Plateau. We find that cumulative CH 4 release decreases with depth, where 0–30 cm-depth sediment accounts for 97% of the whole release. The Q 10 of surface sediment is 2 to 4 times higher than deep layers, but roughly 56% lower than the non-drainage lakes. The response of CH 4 release to warming is mainly driven by microbial communities (49.3%) and substrate availability (30.3%). Our study implies that drainage mitigates CH 4 release from thermokarst lakes and sheds light on crucial processes for understanding permafrost carbon projections.