Sorption of toluene and trichloroethylene to vadose zone soils at different depths

Toluene and trichloroethylene(TCE) were frequently detected in groundwater in the North China Plain.In this study,the sorption of toluene and TCE to soils of vadose zones was studied in batch experiments.The soil samples were taken from three different sites along the waste water rivers in the study area.The highest soil organic carbon content was 1.01%.The soils taken near ground surface showed a higher sorption capacity for toluene and TCE than that of the deep soils.In the experimental concentration range,sorption of organic contaminants,especially TCE,plays an important role in the overall sorption.Sorption of toluene to soils showed high nonlinearity,but linear sorption of trichlorobenzene to soils was observed.There was a closer relationship between sorption affinity and soil organic carbon content for toluene than that for TCE.This indicated that sorption process was also significantly influenced by the properties(e.g.,molecular structure,hydrophobicity).