Methane Fluxes in Cold Season: Assessment by Closed Chamber Method

Resumo

The results of field studies of methane emission to the atmosphere from different landscape elements of West Siberian oligotrophic bog (Mukhrino test plot, Khanty–Mansi autonomous okrug) in the cold season are discussed. The statistical parameters of the process are estimated, and the high variability of methane fluxes and their deviation from the normal distribution are shown. From October to May, the mean arithmetic and median values of methane fluxes were equal to 0.06 ± 0.01 and 0.02 mg С/(m² h), respectively, with the sampling ranging from–0.3 to 0.5 mg С/(m² h). In 22% of cases, the negative fluxes (gas consumption) were observed with the average intensity of–0.03 ± 0.01 mg С/(m² h) and the median of–0.01 mg С/(m² h). At the same time, a considerable underestimation of emission values cannot be excluded, because of the methodological problems of the routine calculation of fluxes by the linear approximation of trends in the gas concentration dynamics in the chamber. The alternative calculation models are provided, and the possible reasons for the experimentally observed phenomenon of methane sink recorded in the chambers on the snow cover surface, including photochemical processes, are discussed.