Partitioning of Dichloro-diphenyl-trichloroethane and Its Metabolites Between Artificial Solid Media and Air

Soil–air partitioning is an important diffusive process affecting the environmental fate of organic compounds. In this study, the soil–air partition coefficients (K SA) for dichloro-diphenyl-trichloroethane and its metabolites (designated as DDTs, the sum of p, p′- and o, p′-isomers of DDT, DDD, and DDE) over a temperature range from 5 to 50 °C in artificial solid media were determined by a solid–fugacity meter. The results showed that log K SA gradually increased with soil organic carbon content (f OC). A reversed relationship was observed between log K SA values and the environmental temperatures (T). The enthalpy changes (ΔH SA) indicated that o, p′-isomers required more energy to release from artificial solid media to the gas phase. Moreover, with increasing temperature, the slope of the regression line of log K SA vs. log K OA (octanol–air partition coefficient) was approaching to 1. Based on factors influencing soil–air partitioning and the experimental data, a multiple parameter (T, f OC, and K OA) model was used to predict the K SA values for DDTs.