ИСТИНА

Mires are the main natural source of methane. West Siberia gains the especial importance in this respect as one of the most paludified region in the world with the mire area of 68.5 Mha or 27% of this region area. However, different investigations conducted in 1993-2007 did not clarify the question about the regional flux: received estimations varied widely from 2 to 22 MtCH4•yr-1. Close examination of these researches revealed a lack of measurements as a main reason of this uncertainty. Aiming at the reliable estimation of the regional emission from West Siberia mire systems, long-term and large-scale investigation was organized. Final estimation proved to be stable (3-4 MtCH4•yr-1), but its dispersion was still high. Probably, seasonal trends of such important methane emission factors as water table level, air and peat temperature adversely affect the estimation uncertainty. To take the seasonal dynamic into account, 164 methane flux measurements at 2 poor fens in West Siberia subtaiga zone were made during the summer 2011. Seasonal increase of methane flux rates was found at both sites. Methane fluxes at the first poor fen were 0.71/1.31/1.52 mgCH4•m-2•h-1 (medians for 9 July/27 July/21 August) while at the second poor fen they were 1.17/2.89/3.14 mgCH4•m-2•h-1 (medians for 12 July/28 July/20 August). This dynamic appeared to be closely related to the seasonal trend of water table level as well as to the air and peat temperature changes (R2 is between 0.5 and 0.7).