Greenhouse gases fluxes at water-air interface of aquaculture ponds and influencing factors in the Min River estuary

Variations of CO2, CH4 and N2O fluxes at water-air interface in the daytime were determined using a floating chamber- gas chromatography method in a mixed culture pond of fish and shrimp from September 2011 to January 2012 in the Shanyutan Wetland of the Min River estuary, southeast China. Meanwhile, the meteorological indicators in ground surface and the physical, chemical and biological indicators of surface water were also measured. The fluxes of CO2, CH4 and N2O at the water-air interface showed an obvious temporal variations during observation. CO2, CH4 and N2O fluxes ranged from -22.15 to 74.79 mg · m-2 · h-1, 0.08 to 6.62 mg · m-2 · h-1 and -9.82 to 47.16 μg · m-2 · h-1, respectively, with the average values of 21.04, 3.15 and 16.58 μg · m-2 · h-1, respectively. The mixed culture pond of fish and shrimp functioned as a source of CO2, CH4 and N2O. The greenhouse gases fluxes at water-air interface were influenced by many factors, including human activities (water quality management and bait launch), growth of fish and shrimp, meteorological factors, and physical and chemical properties of water.