Assessment of the annual diffusive methane emission from the southern tundra thermokarst lake of Western Siberia

Abstract

Lakes are among the most important natural sources of greenhouse gas methane (CH4). Although Western Siberia contains numerous thermokarst lakes, lake CH4 emissions from this region remain unknown. Here we report the results of field measurements of CH4 fluxes conducted by static chamber method in summer 2016 on thermokarst tundra lake "Ledyanoe". Based on the measured values, we estimated annual diffusive CH4 emission from the whole lake by using three approaches: one based on experimental data and two others utilizing modeled data and meteorological records. The quantified annual diffusive CH4 emission following first method was 135 kg C-CH4 year-1 (97-197 kg C-CH4 year-1 95% confidence interval), whereas annual CH4 emission according to next two approaches was 150 kg C-CH4 year-1 (148-151 kg C-CH4 year-1 95% confidence interval) and 131 kg C-CH4 year-1 respectively. Such convergence between the results of different methods can be attributed to compliance of estimates with real annual emission.