Abstract: To study the influence of silty loam interlayer on the migration of benzene and Br^- in unsaturated zone, we analyzed the laws of migration of Br^- and benzene in different soil columns by examining the adsorption of Br^-and benzene by silty loam and sand collected from a foundation pit in Jinniu District of Chengdu. Result showed that the adsorption of Br^- did not increase with the climbing of clay content; the adsorption of benzene increased linearly with the increase of clay content, hence weakening the migration of contaminants. The impact of the concentration of tracer bromide ion on the adsorption of benzene by soil sample was negligible. Moreover, the advancing of wetting front in homogeneous sand was nonlinear, almost consistent above the silty loam interlayer in both soil columns; once entering the silty loam interlayer, the advancing of wetting front weakened evidently. The results indicate that silty loam interlayer has an inhibition effect on infiltration by weakening the migration of Br^- and benzene downward and by adsorbing and purifying benzene.

Key words: silty loam interlayer, homogeneous fine sand, vadose zone, benzene, Br^-, migration rule