Influence of rainfall infiltration on soil colloids-heavy metals co-release and co-migration in infiltration column

A simulated infiltration column filling with the soil collected from infiltration facilities was used to investigate the effect of rainfall infiltration on the co-release and co-migration of soil colloids with Pb, Cu and Cd. The results showed that rainfall infiltration caused the simultaneous release and migration of soil colloids and heavy metals (Cu, Pb and Cd). The results of Zeta potential and RMV values indicated that the movement and migration ability of soil colloids are weakened. The phenomenon of co-release and co-migration of soil colloids and heavy metals were obvious at the beginning of rainfall, and then gradually decreased to stable with the increase of rainfall duration. The co-release and co-migration content of soil colloids and heavy metals increased with the increase of rainfall intensity and the decrease of Na+ concentration in infiltrated water, and firstly increased and then decreased with the increase of pH values of infiltrated water. The soil colloids with small particle size were more capable of carrying heavy metals to migrate.