Effect of soil organic carbon on sorption and desorption of perchloroethylene in soils

The objective of this study was to elucidate the sorption and desorption behaviors of PCE (Perchloroethylene, C2Cl4) in seven soils with different organic carbon (OC) content. Sorption/desorption kinetic and serial dilution desorption experiments were conducted in batch slurries. The sorption distribution coefficient (Kd) of PCE ranged from 0.60 to 4.66 L kg−1. Kd tended to increase as the soil OC increased, but Koc tended to decrease, suggesting that adsorption into the mineral surface was not negligible in soils with low OC. Desorption kinetic data were analyzed by the two-site desorption model. The sorption/desorption of PCE was not reversible over short incubation times due to the presence of a non-desorbable site. The desorbable site fractions of PCE increased and non-desorbable site fractions decreased as the soil OC increased. It is suggested that partition of PCE into soil organic carbon is more reversible than adsorption on soil minerals.