In Japan, approximately 64% of municipal solid waste incineration bottom ash (MSWI BA) is landfilled. Because landfills in Japan are operated without capping, the landfill body is directly exposed to climatic events. Increased frequency of heavy rain is predicted to affect the chemical stabilization of bottom ash (BA) landfill, as rainwater seeps into and interacts with landfill components. This study examined the effect of normal rainfall (15 mm/h) and heavy rainfall (25, 50, and 100 mm/h) events on the leaching behavior of ions (Cl⁻, Na⁺, K⁺, and Ca²⁺) and total organic carbon (TOC) in BA (<10 mm particle size) using a percolation column test. The results showed the decreased leaching of leachate components after heavy rainfall and increased leaching after normal rainfall. In addition, the pH fluctuated around 11–12 after heavy rainfall but decreased to 7–9 after normal rainfall. The carbonation of the leachate and BA layers appears to be the main factor in lowering the pH value. Changes in the TOC and ion concentrations can be explained by dissolution, dilution, and the contact time of water molecules and BA particles. The data showed that the cumulative TOC and ion release rates were not affected by heavy rain intensities. The release rate of leachate components during normal rainfall was higher than that in heavy rainfall in all the scenarios. Significant correlations were found between the leachate components (TOC, Cl⁻, Na⁺, K⁺, and Ca²⁺ concentrations) and rainfall variation.

在日本，约有64％的城市固体废物焚烧底灰（MSWI BA）被填埋。由于日本的垃圾填埋场没有封顶操作，因此垃圾填埋场直接暴露于气候事件中。预计大雨频率的增加会影响底灰（BA）垃圾填埋场的化学稳定性，因为雨水会渗入垃圾填埋场组件并与其相互作用。本研究正常降雨量（15毫米/小时）和暴雨（25，50，和100毫米/小时）上的离子的浸出行为事件（CL的效果^- ，钠⁺，K ⁺，和Ca ²⁺）和BA（<10毫米粒径）中的总有机碳（TOC）（使用渗滤柱测试）。结果表明，暴雨后渗滤液组分的浸出减少，而正常降雨后则增加。此外，暴雨后pH值在11–12左右波动，而正常降雨后pH降至7–9。渗滤液和BA层的碳酸化似乎是降低pH值的主要因素。TOC和离子浓度的变化可以通过水分子与BA颗粒的溶解，稀释和接触时间来解释。数据表明，累积的TOC和离子释放速率不受暴雨强度的影响。在所有情况下，正常降雨期间渗滤液组分的释放速率均高于大降雨。^-，Na ⁺，K ⁺和Ca ²⁺浓度）和降雨变化。