ИСТИНА

Lakes are among the most important natural sources of greenhouse gas methane (CH 4 ). Although Western Siberia contains numerous thermokarst lakes, lake CH 4 emissions from this region remain unknown. Here we report the results of field measurements of CH 4 fluxes conducted by static chamber method in summer 2016 on thermokarst tundra lake "Ledyanoe". Based on the measured values, we estimated annual diffusive CH 4 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 CH 4 emission following first method was 135 kg C-CH 4 year -1 (97-197 kg C-CH 4 year -1 95% confidence interval), whereas annual CH 4 emission according to next two approaches was 150 kg C-CH 4 year -1 (148-151 kg C-CH 4 year -1 95% confidence interval) and 131 kg C-CH 4 year -1 respectively. Such convergence between the results of different methods can be attributed to compliance of estimates with real annual emission.