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

Abstract

Soil–air partitioning is an important diffusive process affecting the environmental fate of organic compounds. In this study, the soil–air partition coefficients (KSA) 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 KSA gradually increased with soil organic carbon content (fOC). A reversed relationship was observed between log KSA values and the environmental temperatures (T). The enthalpy changes (ΔHSA) 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 KSA vs. log KOA (octanol–air partition coefficient) was approaching to 1. Based on factors influencing soil–air partitioning and the experimental data, a multiple parameter (T, fOC, and KOA) model was used to predict the KSA values for DDTs.