| Carbon dioxide ?CO2?, methane ?CH4?, and nitrous oxide ?N2O? are the most important three parts in greenhouse gases. In recent years, with the emission load continued growth, it has brought serious challenges to the global ecological balance. As the most profound and controlled aquatic ecosystem, the study on the mechanism of greenhouse gas emission has an important significance for the realization of emission control. At present, there are few studies on the greenhouse gas in the urban water body. The effects of various meteorological factors and water quality parameters on the greenhouse gas emissions are not clear. This study is based on the researches in Xihe, Xiangyang reservoir, ditches and fish pond in Chongzhou city, Sichuan Province. It analysises CO2, CH4 and N2O emissions from temporal and spatial variation characteristics of different types of water-air interface in Chongzhou, and combined with the water quality parameters and environmental factors to further explore the mechanism of water greenhouse gas emission, in order to provide the scientific basis for water management, and greenhouse gas emissions regulation. The main conclusions include the following aspects:?1? The fluxes of CO2, CH4 and N2O are in the range of -46.41?155.46 mg·m-2·h-1?-711.61?9646.98?g·m-2·h-1 and-1.10?47.67?g·m-2·h-1. The time variation characteristics of CO2 and CH4 showed high in summer and low in winter. The N2O flux showed higher in spring and winter and lower in summer and autumn. Spatial distribution, the CO2 and N2O fluxes of industrial pollution urban settlements and agricultural pollution type rural settlements were higher than other sampling points, CH4 flux at the point of the urban settlements and urban settlements higher.?2? Ditches CO2, CH4 and N2O fluxes range between -2.26?1504.40 mg·m-2·h-1?689.28?40076.80?g·m-2·h-1 and -2.27?70.34?g·m-2·h-1.The characteristics of CO2, CH4 and N2O flux time variation are all shown as high in spring and low in winter. The greenhouse gas fluxes from agricultural and Life pollution ditch is the largest, the greenhouse gas flux of Life pollution ditch is second and the greenhouse gas flux of the agricultural pollution ditch is the least.?3? The CO2, CH4 and N2O flux ranges from -70.06?99.96 mg·m-2·h-1?23.00 ?347.61?g·m-2h-1and -8.01?33.62?·m-2·h-1.The time variation characteristics of CO2 and N2O fluxes were higher in winter and lower in summer than in winter. CH4 flux was higher in summer and lower in autumn and winter.?4? Fish pond CH4, CO2 and N2O flux range -74.30?220.41 mg·m-2·h-1? 14.00?1482.20g?·m-2·h-1 and-3.06?34.76?g·m-2·h-1. The time variation characteristics of CO2 and N2O were high in summer and low in winter, and the time variation of CH4 was high in spring and low in winter.?5? CO2 and CH4 emissions and water temperature, air temperature, rainfall and number of rainy days shows significant positive correlation, there's significant negative correlation between CO2?CH4 and dissolved oxygen, salinity.there's significant negative correlation between N2O emission and salinity,significant positive correlation between N2O emission and rainfall and number of rainy days. CO2 emissions and NH4+-N?TN?TP are significant positive correlation and are negatively correlated with the NO3--N and Chl-a. NH4+-N and Chl-a are negatively correlated with the CH4 emissions, TN?TP?NO3--N are significant positive correlation with CH4 emissions. N2O emissions and the NH4+-N has negarive correlation. |
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