Study On Methane Emission From Littoral Zone Of Huahu Lake, Zoige Plateau

The Zoige wetland on the eastern fringe of Qinghai-Tibetan Plateau, with averagealtitude between 3,400 and 3,600m, is the watershed of Yangtze River and YellowRiver. There are large area of peatland, subalpine meadow and lakes in this region.Due to its high elevation, transitional topology and high fluctuation of climate, theZoige wetlands represent one of the most fragile wetland ecosystems in China. And asa result of remote location and harsh environment conditions, the researches on theZoige wetland are relatively rare, especially the researches on the methane emissionfrom littoral zone of alpine lakes. Variations of methane emission rates as measuredby the method of static chamber-gas chromatography (GC) were detected fromlittoral zone of alpine lake on the Zoige Plateau. Relationships between methaneemission rates and environmental factors were analyzed. It is concluded that:1. The average methane emission rate in the littoral zone of Huahu Lake, ZoigePlateau is 0.315 mg·m^-2·h^-1, with evident spatial and temporal variations. The littoralzone has different methane effiuxes with-0.054, 0.471, and 0.493 mg·CH₄·m^-2·h^-1in June, July and August respectively. Different types of wetland have differentmethane emission rates, with value of 0.464, 0.477, and 0.005 mg·CH₄·m^-2·h^-1 forPolygonum amphibium wetland (PA), Shoal (S) and Kobresi tibetica meadow(KT), respectively.2. The soil temperature at 10cm is significantly correlated with the methane effiuxesin littoral zone of Huahu Lake, Zoige Plateau, and which is one of the most important factors influencing the methane emission from this district. The activities of soilmicroorganisms rise under higher soil temperature and increases oxygen consumptionand decreases Eh, which is in favor of the methanogensis, and enhances theproduction of methane in soil.3. The correlation between the standing water and methane effluxes from littoralzone of Huahu Lake is not significant. Because of the standing water, the anaerobicconditions of wetland soil have been enhanced, and are favor to the decomposition oforganic matter. And the anaerobic conditions strengthen the methanogensis' activities,thus the methane production, which release to the atmosphere by diffusion, ebullitionand aerenchymal plants. With the water level's increase, more methane produced insoil which is transferred by ebullitions or diffusion are oxidated, thus reduce themethane release to the atmosphere.4. The height and aboveground biomass of vegetation are not significant related tothe methane effluxes from littoral zone of Huahu Lake, Zoige Plateau. The vegetationprovides substrates for methanogensis by litter and root exudates; act as thetransportation way of methane between soil and atmosphere; influence the methaneemission of wetland ecosystems with other environment factors.