EMISSION OF CARBON DIOXIDE IN THE COASTAL WETLANDS OF THE LIAOHE DELTA, CHINA

Carbon dioxide is likely the major greenhouse gas in the coastal wetland as the availability of sulfate inhibits CH₄ release. Therefore, the study of the CO₂ emission mechanism in the eco-system of the coastal wetland is of significance to carbon cycle and its budget. For this purpose, the LI-8100A soil respiration system was adopted to measure the soil CO₂ flux in the Liaohe Delta during May, 2012, and the method of enclosure chamber measurement was used to explore wetland CO₂ emission mechanism for three types of coastal wetlands: unvegetated wetlands, Suaeda salsa and Phragmites australis wetlands. It discovered that during this season of a year the Phragmites wetland has a higher respiration rate(3 041.59±320.66 mg·m^-2·h^-1)than the Suaeda wetland(534.09±56.06 mg·m^-2·h^-1), and both are higher than relevant records of CO₂ flux from literatures. Aboveground biomass has a positive liner correlation with the plant respiration rate. In the wetland ecosystem, CO₂ released from the soil accounts for ~60% of total CO₂ emission. It is also observed that the CO₂ emission will be significantly increased after wetland vegetation being destroyed, that means that the harvest of wetland plants is the cause of significant release of greenhouse gas CO₂.