干湿交替诱导含重金属细颗粒物在多孔介质中释放迁移的作用机制

为探究含重金属细颗粒引起土壤重金属污染的形成机制,以矿渣为对象，采用柱试验，研究了干湿交替诱导含重金属细颗粒在多孔介质中释放迁移的特征与机制。结果表明：干湿交替显著促进了粒径在342～955 nm的矿渣颗粒的释放迁移，该促进作用由3种作用机制联合引起，且与落干期时长有关，而与干湿交替次数和落干期排列顺序无关；释放迁移的矿渣颗粒在石英砂多孔介质中发生了累积，落干时间越长，累积质量越高，累积质量随介质深度的增加而减少，累积颗粒的粒径分布随介质深度无明显变化。细颗粒的释放迁移是含重金属细颗粒引起土壤重金属污染的主要原因，固应对干湿交替下含重金属细颗粒的环境行为给予重视。

Release and Transport Mechanisms of Metal-rich Fine Particles in Porous Media During Drying-Wetting Cycles

In order to explore the formation mechanism of heavy metal contamination in soil caused by metal-rich fine particles,we carried out column experiments with mine tailings as object,and investigated the release and transport mechanisms of metal-rich fine particles in porous media under drying-wetting cycles.Results show that drying-wetting cycles significantly enhance the release and transport of tailing particles ranged from 342 nm to 955 nm.This enhancing effect is resulted from the combined action of three mechanisms,and highly depends on the drying duration instead of the number or order of drying-wetting cycles.Furthermore,the released and transported tailing particles are accumulated in the porous media,namely quartz sands.The longer the drying duration is,the more the accumulative mass is.In particular,the accumulative mass decreases with the increase of media depth,but the size distribution of the accumulated tailing particles changes little with the increase of media depth.Finally,the release and transport of fine particles should be responsible for the heavy metal contamination in soil caused by metal-rich fine particles,and we should pay attention to the environmental behavior of metal-rich fine particle under drying-wetting cycles.