Temperature-dependence of soil/air partition coefficients for selected polycyclic aromatic hydrocarbons and organochlorine pesticides over a temperature range of −30 to +30 °C

The soil/air partition coefficients (KSA) for two polycyclic aromatic carbons (PAHs) and six organochlorine pesticides (OCs) were determined by a solid-phase fugacity meter over a wide temperature range of −30 to +30 °C in a paddy field soil. Literature values for PAHs and OCs obtained by the same method were 1.9–5.1 times of present values at +20 °C. Experimentally determined KSA ranged over six orders of magnitude, with log KSA from 4.5 for α-hexachlorocyclohexane at +30 °C to 10.4 for trans-nonachlor at −20 °C. Separate linear regressions of log KSA and reciprocal absolute temperature were employed at temperatures above 0 °C and below 0 °C. The calculated enthalpies associated with the phase transfer from the soil to the air (ΔHSA) over 0 to +30 °C range from 78 to 108 kJ mol−1, which are in a good agreement with the literature values.