Abstract:In six structurally packed columns (two homogeneous and four heterogeneous) constructed with two kinds of glass beads, we studied the effect of media heterogeneous on the transport behaviors of tracer and montmorillonite colloids in saturated condition. The results showed that the breakthrough curves of tracer were similar in two homogeneous columns, and the mobility of montmorillonite colloids in coarse media was stronger than that in fine media. For the column containing macroporous channel, the presence of preferential flow path resulted in an earlier breakthrough of tracer and montmorillonite colloids, and larger contact area between macroporous channel and fine grains caused a lower breakthrough peak and a stronger tailing. In column packed with homogeneous mixture of coarse and fine grains, the shape of tracer breakthrough curves were similar to that in homogeneous columns, and the mobility of montmorillonite colloid was between that in the homogeneous columns (coarse and fine grain). More montmorillonite colloids were retained at coarse-fine grain interface in the layered column. The results have shown that heterogeneity has an important effect on the transport of the tracer and montmorillonite colloid in soil and underground environment.