| Since the Industrial Revolution, the concentration of the greenhouse gases such as carbon dioxide(CO2), methane(CH4), nitrous oxide (N2O) in the atmosphere were ascended for the humankind activities and the petrifaction fuel burning. This phenomenon will cause the globe warmer and warmer. It will also bring many bad influences.Taihu Lake is one of the five largest fresh water lakes in china. It is in the south of the delta of the Yangtze River and it is a typical shallow lake with flat bottom in the middle and low reaches of the Yangtze River. In this paper, through observing and analyzing the carbon dioxide(CO2), methane(CH4), nitrous oxide (N2O) fluxes of the water-air interface in the Lake Taihu, we found that changes of those fluxes of water-air interface have some rule. (1) Carbon dioxide flux: There is a clear daily change rule that the water of Taihu Lake is a sink of carbon dioxide of air in the daytime while at night the water is source in sunshine day. The average CO2 fluxes of spring , summer, autumn , winter are respectively -0.81 mg/(m2·h), -5.12 mg/(m2·h), -5.29 mg/(m2·h), -1.81 mg/(m2·h) in sunshine day in Meiliang Bay. And in the Dongtaihu Lake the average CO2 fluxes is 11.36 mg/(m2·h) in spring in cloudy day and -2.45 mg/(m2·h) in summer in sunshine day. CO2 flux has good relationship with temperature, pH, dissolve oxygen, alkalinity, chlorophyll.(2) Methane(CH4) flux: There isn't obvious daily change rule of CH4 flux. CH4 flux is related to aquatic plants category , water quality , weather condition , seasonal alteration. A rule has been found that flux of float-leaf plant is bigger than macrophytes, and the flux of macrophytes is bigger than phytoplankton. (3) N2O flux: Sometime the lake is source and sometime the lake is sink. The daily average N2O flux of Taihu Lake is between -0.002 mg/(m2· h) and 0.066 mg/(m2· h). |
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