3:30 PM - 4:45 PM
[ACG24-P14] Multi-year response of CH4 efflux to wetting at Indigirka Lowland in Northeastern Siberia
Keywords:methane flux, interannual variation, isotope ratio, taiga-tundra boundary
In this study we assessed interannual variation in chamber CH4 efflux and in delta-13C-, delta-D-CH4 near Chokurdakh (70.62 N, 147.90 E) over summers of 2009-2013 to understand relationship between CH4 efflux and environmental factors based on the 3 processes of CH4.
CH4 efflux was around the detection limit at dry tree mounds through the observation period, while large interannual variation was observed at wet areas of sphagnum moss and sedges. Wet event concurrent with the highest precipitation occurred in 2011 and CH4 efflux increased at wet areas in the same year. Although water level decreased from 2011 to 2013, large CH4 emission continued. Moreover, dissolved CH4 concentration in soil pore water (at 10-15 cm depth) increased by 1 order of magnitude from 2011 to 2012 and kept high till 2013. CH4 isotopes implies that CH4 oxidation was depressed in 2012 after the wetting in 2011, suggesting soil reduction induced by the wetting proceeded over multiple years, which may have affected dissolved CH4 concentration and CH4 efflux. Such variation in CH4 efflux and in dissolved CH4 concentration will be discussed in relation to the 3 processes in this presentation.