ABSTRACT
The chemical 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is one of the most toxic compounds known to man. Soil samples collected from a number of sites in the US have been found to contain significant levels of TCDD. The sorptive and desorptive behavior of TCDD has been investigated using soils of various organic carbon contents and a range of equilibration periods from 1 to 90 days. These studies have employed water, methanol, toluene, and mixtures of water/methanol and water/toluene as the liquid phase. The presence in water of solvents — miscible and/or immiscible — may enhance liquid phase solubility and hence improve transport through soils. The equilibrium aspect of the transport of these latter solutes in soil and sediment systems can be expressed in terms of the water-soil partition coefficient. Soil concentrations of TCDD were determined by difference from total initial TCDD minus total TCDD in the liquid phase.
