Diurnal Variations Of Greenhouse Gas Fluxes From The Marsh In The Min River Estuary

Minjiang River Estuary wetland is an important natural tidal estuary wetland in China. The characteristic environmental factor of the study area is the tide.The emission of CO2,CH4,N2O in the wetland have been widespread concerned. Minjiang River Estuary was chose as the study area.The diurnal variation of CO2,CH4,N2O in different tidal status were determined and analyzed by static chamber and gas chromatography method or suspension chamber and gas chromatography method.The effect of tidal level and other environmental factors on the fluxs of the three greenhouse gases.The results showed that:(1)During the low tide day in april,the daily mean flux of CO2 was 41.03 mg-m-2-h-1.The daily mean fluxs of CO2 during the high tide day in april and September were 11.95 and -22.68 mg-m-2·h-1,respectively,the nighttime fluxs were higher than that of daytime.when the site was submerged by tide water,the CO2 flux was larger than the time exposure to the air during the daytime, the opposite rusult was got in the night time.(2) The daily mean fluxs of CH4 during the low tide day in april and september were 4.43 and8.13 mg·m-2·h-1,respectively. The daily mean fluxs of CH4 during the hige tide day in april and September were 1.39 and 3.25 mg·m-2·h-1,,respectively. The daytime fluxs were higher than that of nighttime. when the site was submerged by tide water,the mean CH4 flux was lower than the time exposure to the air.(3) The daily mean fluxs of N2O during the low tide day in april and september were-1.87 and 128.76μg·m-2·h-1,respectively. The daily mean fluxs of N2O during the hige tide day in april and september were 45.04 and -9.19μg·m-2·h-1,respectively.The mean fluxs during the submerge period were higher than the exposure period expect the nighttime in april.(4) Tidal level,temperature,wind speed has great influence on the CO2,CH4,N2O fluxs.