... increase of the amount of HWCs while there is a slight change of the peak concentration in Andisol (Fig. 2 (b)) except for the more pronounced tailing of the BTCs with the increase of HWCs. The peak ... reflects that the solutes spread larger during the course of transport in Andisol. On the other hand, opposite results are shown in unsaturated columns since the degree of spreading of solutes ... indicated that the retardation factor increased with the increase in the amount of HWCs and reached up to 3.3 and 1.7 in silica sand and Andisol, respectively. In particular, the effect of HWCs on...