Abstract Greenhouse gas emissions from physical permafrost thaw disturbance and subsidence, including the formation and expansion of thermokarst (thaw) lakes, may double the magnitude of the permafrost carbon feedback this century. These processes are not accounted for in current global climate models. Thermokarst lakes, in particular, have been shown to be hotspots for emissions of methane (CH4), a potent greenhouse gas with 32 times more global warming potential than carbon dioxide (CO2) over a 100-year timescale. Here, we synthesize several studies examining CH4 dynamics in a representative first-generation thermokarst lake (Vault Lake, informal name) to show that CH4 production and oxidation potentials vary with depth in thawed sediments beneath the lake. This variation leads to depth-dependent differences in both in situ dissolved CO2:CH4 ratios and net CH4 production responses to additional warming. Comparing CH4 production, oxidation, and flux values from studies at Vault Lake suggests up to 99% of produced CH4 is oxidized and/or periodically entrapped before entering the atmosphere. We summarize these findings in the context of CH4 literature from thermokarst lakes and identify future research directions for incorporating thermokarst lake CH4 dynamics into estimates of the permafrost carbon feedback.

中文翻译：

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热岩溶湖环境中甲烷动力学的综合

摘要 物理永久冻土融化扰动和沉降产生的温室气体排放，包括热岩溶（融化）湖的形成和扩张，可能使本世纪永久冻土碳反馈的幅度增加一倍。当前的全球气候模型没有考虑这些过程。尤其是热岩溶湖泊，已被证明是甲烷 (CH4) 排放的热点，甲烷是一种强效温室气体，在 100 年的时间尺度内，其全球变暖潜力是二氧化碳 (CO2) 的 32 倍。在这里，我们综合了几项研究，考察了具有代表性的第一代热岩溶湖（Vault Lake，非正式名称）中的 CH4 动力学，以表明 CH4 的产生和氧化潜力随湖底解冻沉积物的深度而变化。这种变化导致原位溶解 CO2 的深度依赖差异：CH4 比率和净 CH4 产量对额外变暖的响应。比较来自 Vault Lake 研究的 CH4 生产、氧化和通量值表明，多达 99% 的 CH4 在进入大气之前被氧化和/或定期捕获。我们在来自热岩溶湖泊的 CH4 文献的背景下总结了这些发现，并确定了将热岩溶湖泊 CH4 动力学纳入永久冻土碳反馈估计的未来研究方向。