Chai Xue-Si, Hao Qing-Ju, Huang Zhe, Fan Zhi-Wei, Jiang Chang-Sheng
Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, College of Resources and Environment, Southwest University, Chongqing 400715, China.
Huan Jing Ke Xue. 2017 Oct 8;38(10):4370-4379. doi: 10.13227/j.hjkx.201702003.
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 CH emissions from subtropical reservoirs. The experimental period lasted two years from September 2010 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 CH 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 CH emissions showed a single peak pattern with the climax during its flooding period, and then showed not regular CH emission sources or sinks alternately in the second year, whereas the CH fluxes at 165 m, 155 m, and 140 m presented a single-peak shape with winter climax. During the entire observation period, the CH emission fluxes at 180 m were stable and showed no obvious peaks. In addition, CH 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 CH cumulative emissions at the five elevations was 140 m (99.58 kg·hm) > 155 m (82.98 kg·hm) > 165 m (65.38 kg·hm) > 180 m (6.32 kg·hm) > 175 m (4.27kg·hm), suggesting that the soil was more conducive to CH production when the flooding period was longer. Correlation analysis indicated that there were no significant correlations between CH fluxes and the soil carbon component and pH on land and during the drainage period but CH fluxes increased with the increase in soil water content. There was a significant linear negative correlation between CH emissions from the gas-water interface at 140 m and in water. The soil moisture content was one of the key factors affecting the CH fluxes during the drainage period, while during flooding period, the CH fluxes were regulated by flooding depth.
在三峡水库王家沟典型的水位下降区选取了五个水位（180米、175米、165米、155米和140米）来研究亚热带水库的CH排放。实验期从2010年9月持续到2012年8月，为期两年。本研究采用了排水期的静态不透明箱法和洪水期的浮动箱法。175米、165米和155米的海拔均位于水位下降区，而180米的海拔位于陆地，从未被淹没。140米的海拔永久被淹没，用作对照区。结果表明，在实验的第一年，175米和165米处的CH通量没有显著趋势，而155米和140米处的通量呈现单峰模式，夏季达到峰值。在175米处，CH排放在其洪水期呈现单峰模式，然后在第二年交替出现不规则的CH排放源或汇，而165米、155米和140米处的CH通量呈现冬季峰值的单峰形状。在整个观测期内，180米处的CH排放通量稳定，没有明显峰值。此外，175米、165米和155米处洪水期的CH通量高于排水期。五个海拔高度的年度CH累积排放量顺序为140米（99.58千克·公顷）>155米（82.98千克·公顷）>165米（65.38千克·公顷）>180米（6.32千克·公顷）>175米（4.27千克·公顷），这表明洪水期越长，土壤越有利于CH的产生。相关性分析表明，在陆地和排水期，CH通量与土壤碳成分和pH值之间没有显著相关性，但CH通量随土壤含水量的增加而增加。140米处气-水界面的CH排放与水中的排放之间存在显著的线性负相关。土壤含水量是排水期影响CH通量的关键因素之一，而在洪水期，CH通量受洪水深度调节。
