In medium sand and coarse sand, almost 90% of the chlorobenzene was removed from the system after 24 h, while more than 30% of the chlorobenzene within the silt still remained.These differences are caused by various reasons. Firstly the adsorption capacity of the soils to the contaminant is different [15], forsilt, it has a large surface area and NOM content which makes the contaminant hard for desorption from the silt compared with that in other two soils