Abstract: 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.

Key words: drying wetting cycle, fine particle, heavy metal, porous media, release and transport