Zijin School of Geology and Mining, Fuzhou University, Fuzhou City, Fujian Province, China; Key Laboratory of Geohazard Prevention of Hilly Mountains, Ministry of Natural Resources (Fujian Key Laboratory Of Geohazard Prevention), Fuzhou City, Fujian Province, China.
Zijin School of Geology and Mining, Fuzhou University, Fuzhou City, Fujian Province, China.
Waste Manag. 2024 Dec 15;190:370-381. doi: 10.1016/j.wasman.2024.09.034. Epub 2024 Oct 10.
Soil column tests were conducted to investigate methane oxidation efficiency in three configurations of earthen landfill cover under two drying stages separated by an applied rainfall, including the monolithic evapotranspiration (ET) cover, the cover with capillary barrier effect (CCBE) and the three-layer cover. Comprehensive measurements were also documented for water-gas response in soil for analyzing the experimental outcomes. The maximum methane oxidation efficiency of three-layer cover, monolithic ET cover, and CCBE were about 71 %, 62 % and 58 %, respectively. This was because the three-layer cover had the largest oxygen (O) concentration in soil above depth of 400 mm, where methane oxidation mainly occurred. This was due to the good airtightness of the bottom hydraulic barrier layer, which led to the lowest air pressure above depth of 400 mm, thereby promoting the entry of atmospheric O into the soil. The monolithic ET cover generally had a larger methane oxidation efficiency than CCBE during the first drying stage by up to 12 %, while the trend reversed overall during the second drying stage, likely due to the enhanced air-tightness of CCBE caused by higher soil water content after rainfall induced by the capillary barrier effects. The methane oxidation efficiency for each landfill cover became lower by up to 30 % during the second drying stage than that during the first drying stage, owing to the higher water content during the second drying stage after rainfall, leading to a larger gas pressure and hence a lower O concentration at shallow soil.
进行了土柱试验，以研究在两次降雨间隔的两个干燥阶段下，三种类型的封场覆盖层（整体蒸发蒸腾覆盖层、具有毛细屏障效应的覆盖层和三层覆盖层）中甲烷氧化效率。还记录了土壤中的水气响应综合测量数据，以分析实验结果。三层覆盖层、整体蒸发蒸腾覆盖层和具有毛细屏障效应的覆盖层的最大甲烷氧化效率分别约为 71%、62%和 58%。这是因为在主要发生甲烷氧化的 400 毫米深度以上的土壤中，三层覆盖层具有最大的氧气（O）浓度。这是由于底部水力屏障层具有良好的气密性，导致在 400 毫米深度以上的气压最低，从而促进大气 O 进入土壤。在第一个干燥阶段，整体蒸发蒸腾覆盖层的甲烷氧化效率一般比具有毛细屏障效应的覆盖层高 12%，而在第二个干燥阶段则相反，这可能是由于降雨后毛细屏障效应导致土壤含水量增加，从而增强了具有毛细屏障效应的覆盖层的气密性。由于第二个干燥阶段降雨后的含水量较高，导致气体压力较大，浅层土壤中的 O 浓度较低，每个封场覆盖层在第二个干燥阶段的甲烷氧化效率比第一个干燥阶段低 30%。
