Japan Geoscience Union Meeting 2014

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Poster

Symbol A (Atmospheric, Ocean, and Environmental Sciences) » A-CG Complex & General

[A-CG36_30PO1] Science in the Arctic Region

Wed. Apr 30, 2014 6:15 PM - 7:30 PM Poster (3F)

Convener:*Saitoh Sei-Ichi(Faculty of Fisheries Sciences, Hokkaido University), Jun Inoue(National Instituteof Polar Resarch), Naomi Harada Naomi(Japan Agency for Marine-Earth Science and Technology), Rikie Suzuki(Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology)

6:15 PM - 7:30 PM

[ACG36-P16] Methane Oxidation Potential of Arctic Wetland Soil of a Taiga-Tundra Ecotone in Northeastern Siberia

*Jun MURASE1, Atsuko SUGIMOTO2, Ryo SHINGUBARA3, Trofim C. MAXIMOV4 (1.Grad. Sch. Bioagr. Sci., Nagoya Univ., 2.Fac. Earth Environ. Sci., Hokkaido Univ., 3.Grad. Sch. Environ. Sci., Hokkaido Univ., 4.Inst. Biol. Problems of Cryolithozone)

Keywords:Methane oxidation, tundra, peat

Arctic wetlands are significant sources of atmospheric methane and the observed accelerated warming of the arctic causes increased methane formation in water-saturated tundra soil with deepened permafrost thawing. Methane oxidation is regarded as the key process to regulate methane emission from wetlands. In this study we determined the potential methane oxidation rate of the wetland soils of a Taiga-Tundra transition zone in Northeastern Siberia with special reference of the spatial heterogeneity and response to environmental parameters. The surface peat soil samples (0-10 cm) were collected in the summer of 2012 and 2013 from depressions that were covered with tussocks of sedges and Sphagnum spp. and mounds vegetated with moss and larch trees. The potential methane oxidation rate was estimated by a bottle incubation experiment in which homogenized soil samples were incubated with methane at the initial concentration of 0.5-0.8 %v/v. Soil samples from the mounds showed no detectable methane oxidation, whilst the soils collected from depressions exhibited active methane oxidation with no lag. The potential methane oxidation rates at 15 oC were of 270 and 190 nmol h-1 g-1 dw in the moss- and sedge-dominated zones, respectively. Methane oxidation was active over the depths including the water-saturated anoxic layers, suggesting the resilience of methane oxidizing bacteria. The maximum methane oxidation rate was recorded in the layer above the water-saturated layer: the surface (0-2cm) layer in the sedge-dominated zone and in the middle (4-6 cm) layer in the moss-dominated zone. Temperature-dependent methane oxidation was observed at the range of temperature from 0 to 15 oC. The estimated threshold temperature of methane oxidation was -4 to -11 oC, which suggested methane oxidation at subzero temperatures. Treatment with inorganic nutrients and black carbon did not affect the potential methane oxidation rate.