中文摘要：

为了探讨亚热带水库消落带CH4的排放规律,选取三峡库区王家沟一典型消落带内5个高程（180、175、165、155及140 m）为研究对象,其中175、165和155 m位于消落带上,180 m高程为永不淹水的陆地,140 m高程为永久淹水对照区.采用静态暗箱、浮箱/气相色谱法对各高程生态系统CH4的排放进行了为期两年的连续观测.结果表明,175 m和165 m高程在实验观测的第一年CH4排放通量变化不明显,而155 m和140 m高程处表现为单峰型的夏季CH4排放高峰;次年在三峡水库实现最高蓄水位175 m后,175 m高程在淹水期间CH4排放呈现单峰态,之后表现为源汇交替的无规律排放,而165m、155 m以及140 m高程均大致呈现出冬季高CH4排放的单峰态;在整个观测期间,180 m高程CH4排放通量较为稳定,未出现明显峰值.另外,位于消落带上的175、165和155 m高程均表现为淹水期CH4排放大于落干期.各高程处CH4年累积排放量为140 m（99.58 kg·hm^-2）〉155 m（82.98 kg·hm^-2）〉165 m（65.38 kg·hm^-2）〉180 m（6.32 kg·hm^-2）〉175 m（4.27 kg·hm^-2）,表明淹水时间越长的土壤,其环境更有利于CH4的产生.相关性分析显示,陆地与消落带落干期的CH4排放与土壤碳组分及pH无显著相关性,但CH4排放通量随土壤含水率的增加而增大;水-气界面上,140 m高程CH4排放通量与水深有显著线性负相关关系;表明土壤含水率是影响消落带落干期CH4排放的关键因子之一,而水-气界面上CH4的排放则受到淹水深度的调控.

英文摘要：

Five levels（ 180 m,175 m,165 m,155 m,and 140 m） in a typical drawdown area in Wangjiagou in the Three Gorges Reservoir were selected to study CH4 emissions from subtropical reservoirs. The experimental period lasted two years from September2010 to August 2012. The methods of static opaque chambers during the drainage period and floating chambers during flooding period were used in this study. The elevations of 175 m,165 m,and 155 m were all located in the drawdown area,whereas the 180 m elevation was located in the land and never flooded. The 140 m elevation was permanently flooded and used as a control area. The results showed that the CH4 fluxes showed no significant trends at 175 m and 165 m in the first year of the experiment,while the fluxes showed a single peak pattern with the climax in the summer at 155 m and 140 m. At 175 m,the CH4 emissions showed a single peak pattern with the climax during its flooding period,and then showed not regular CH4 emission sources or sinks alternately in the second year,whereas the CH4 fluxes at 165 m,155 m,and 140 m presented a single-peak shape with winter climax. During the entire observation period,the CH4 emission fluxes at 180 m were stable and showed no obvious peaks. In addition,CH4 fluxes were higher during the flooding period than in the drainage period at 175 m,165 m,and 155 m. The order of the annual CH4 cumulative emissions at the five elevations was 140 m（ 99. 58 kg·hm^-2） 155 m（ 82. 98 kg·hm^-2） 〉165 m（ 65. 38 kg·hm^-2） 〉180 m（ 6. 32 kg·hm^-2） 〉175 m（ 4. 27 kg·hm^-2）,suggesting that the soil was more conducive to CH4 production when the flooding period was longer.Correlation analysis indicated that there were no significant correlations between CH4 fluxes and the soil carbon component and pH on land and during the drainage period but CH4 fluxes increased with the increase in soil water content. There was a significant linear negative correlation between CH4 emissions from the gas-water interface at 140 m and in water. The soi