中文摘要：

三峡水库温室气体效应近年来备受关注．为揭示三峡水库典型支流澎溪河水－气界面CO2和CH4通量的昼夜动态规律，明晰短时间尺度下该水域温室气体释放的影响因素，在2010年6月至2011年5月的一个完整水文周年内，选择4个具有代表性的时段（2010年8、11月和2011年2、5月）对澎溪河高阳平湖水域开展昼夜跟踪观测．结果表明：2010年8、11月和2011年2、5月4次采样的CO2日总通量值分别为一8．34、73．94、28．13和一20．12mmol／（m2·d），相应的CH4日总通量值分别为2．22、0．11、0，32和7，16mmol／（m2·d），不同时期昼夜变化明显．研究水域CO2和CH4通量过程不具同步性：CO2昼夜通量变化可能更显著地受到水柱光合／呼吸过程的影响，但瞬时气象过程（水汽温差、瞬时风速等）在高水位时期亦可对CO2通量产生显著影响；CH4昼夜通量变化与水温条件改变更为密切．

英文摘要：

There is a wide concern on the greenhouse gases emission due to dam construction in recent years. However, dial variation of reservoir greenhouse gases fluxes was seldom reported. To track the diel dynamics of greenhouse gases fluxes in the backwater area of the Pengxi River, Three Gorges Reservoir and elucidate the controlling factors of the fluxes, four 24-h monitoringcampaigns in Aug. , Nov. of 2010 and Feb. , May of 2011 were carried out in a whole reservoir operation year in Lake Gaoyang. We h）und that the daily total emission of CO2 were -8.34, 73.94, 28.13 and -20.12 mmol/（ m2 ·d） in the above periods, respectively. While the fluxes of CH4 during these 4 monitoring campaigns were 2.22, 0.11, 0.32 and 7.16 mmol/（ m2 · d）, respectively. The diel varied among the campaigns. The emission of CO2 and CH4 were showed to have different pathways for their asynchronous fluxes during the study. A correlation analysis revealed that photosynthesis and respiration in water column was a key controlling process for CO2 fluxes in this area. Furthermore, instantaneous meteorological parameters, i.e. wind speed, waterair temperature differences, were also significant factors that impact the fluxes of CO2 in high water level operation period of the reservoir. However, the variations of CH4 might be regulated by water temperature changes.