Methane Emissions From the Qinghai‐Tibet Plateau Ponds and Lakes: Roles of Ice Thaw and Vegetation Zone

Abstract

Abstract Comprehensive seasonal observation is essential for accurately quantifying methane (CH 4 ) emissions from ponds and lakes in permafrost regions. Although CH 4 emissions during ice thaw are important and highly variable in high‐latitude freshwater ponds and lakes (north of ∼50°N), their contribution is seldom included in estimates of aquatic‐atmospheric CH 4 exchange across different alpine ecosystems. Here, we characterized annual CH 4 emissions, including emissions during ice thaw, from ponds and lakes across four alpine vegetation zones in the Qinghai‐Tibet Plateau (QTP) permafrost region. We observed significant spatial variability in annual CH 4 emission rates (8.44−421.05 mmol m −2 yr −1 ), CH 4 emission rates during ice thaw (0.26−144.39 mmol m −2 yr −1 ), and the contribution of CH 4 emissions during ice thaw to annual emissions (3−33%) across different vegetation zones. Dissolved oxygen concentration under ice, along with substrate availability and water salinity, played critical roles in influencing CH 4 flux during ice thaw. We estimated annual CH 4 emissions from ponds and lakes in the QTP permafrost region as 0.04 (0.03−0.05) Tg CH 4 yr −1 (median (first quartile−third quartile)), with approximately 20% occurring during ice thaw. Notably, the average areal CH 4 emission rate from ponds and lakes in the QTP permafrost region amounts to only 8% of that from high‐latitude waterbodies, primarily due to the dominance of large saline lakes with lower CH 4 emission rates in the alpine permafrost region. Our findings emphasize the significance of incorporating comprehensive seasonal observation of CH 4 emissions across different vegetation zones in better predicting CH 4 emissions from alpine ponds and lakes.