Study on the Co-Migration of Pb with Soil Colloids under Rainfall

Abstract

In this experiment, clay loam, fine sandy loam and silty loam collected from the farmland (FL), floodplain (FP) and Loess platform (LP) in Changchun separately were chosen to study the role of rainfall on the migration of heavy metal (Pb)-colloid complexes quantitively through soil column simulation in laboratory. The purpose of this study is to illuminate the tendency for colloid-Pb co-migrating to deep soil and groundwater. The study shows whether how the mechanism between colloid and heavy metal acts, the processes exist in common. First, through some sort of adsorption, heavy metal form complexes with colloids, and co-migrate in the underground environment, which is called a co-migration mechanism. And Pb migrated out the FL, LP, and FP soil column contain 28.4%、25.7% and 22.6% complexes separately. Second, the heavy metal complexes with colloids have a certain stability and mobility. Third, in migrating process, the presence of colloids increases the migration concentration and amount of heavy metal (Pb). And the quantitative of Pb migrated out the FL, LP and FP soil column which added colloids are 1.37、1.36 and 1.25 double control columns separately. Forth, the presence of colloids reduces the reduction ability heavy metal (Pb), and shortens the consumption time for heavy metal (Pb) migrating to a certain depth of groundwater. And the time consuming of Pb migrating to groundwater with same deep is Loess horizon>floodplain horizon>farmland horizon.