Methane Emission In Reed Marsh Of Minjiang River Estuary And The Discussing Of Environmental Influencing Factors

The Minjiang River Estuary wetland is one of the most representative and typical Estuary wetlands in southeast seashore of China.Methane production,oxidation, emission,methane concentrations from different soil layers in the reed marsh of Minjiang River Estuary were measured using laboratory incubation,the enclosed chamber technique and gas chromatograph methods.The effects of environmental factors on methane emission flux were also discussed.The results showed:(1)The range of soil methane production rates were 0.0018～0.2007μg·g^-1·d^-1;the range of soil methane oxidation rates were 0.0240～0.0516μ·g·g^-1·d^-1;the range of pore water methane production rates were 0.29～2.38μg·L^-1·d^-1.(2)Methane emission fluxes were separated into three periods that is before flood tide,in the period of flood and ebb and after ebb.The range of methane emission flux were 1.42～11.86 mg·m^-2·h^-1,0.84～13.21mg·m^-2·h^-1 and 0.31～12.72mg·m^-2·h^-1, respectively.There were significant seasonal variations,the peak and low values were appeared on July,December;July,March and June,December,respectively.Situ observation didn't find significant difference from the three periods.(3)The peak and low values ofdiel variation of methane emission fluxes appeared on 9～10 h and 5～6 h in summer;diel variations appeared two peak values,9～10 h and 21～22 h in winter,the low values also appeared on 5～6 h.(4)The range of soil methane concentrations were from 0.08%to 0.72%;the range of pore water methane cocentrations were 1.47～234.65μmol/L.(5)Air temperature and soil(tidal water) temperature were the most important factors controlling methane emission,the soil salinity only correlated with methane emission fluxes after ebb.(6)The total annual methane emission flux was 39.46 g·m^-2·a^-1.