Temperature-dependence of soil/air partition coefficient for polychlorinated biphenyls at subzero temperatures

Abstract: Soil/air partition coefficients (K SA) were measured experimentally on a silty clay loam soil spiked with polychlorinated biphenyls (PCBs) over a wide range of environmentally relevant temperatures (−30 to +30°C). Measured K SA-values ranged over 6.4 orders of magnitude, with log K SA from 4.3 for PCBs 10/4 at +30°C to 10.7 for PCBs 77/110 at −30°C. Higher than expected, K SA-values were observed at subzero temperatures (by up to one order of magnitude, at −30°C). The plots of log K SA vs. reciprocal absolute temperature show a change in slope at 0°C. A log–log linear regression of K SA vs. octanol/air partition coefficient (K OA) has a slope close to 1, indicating that K OA is a good descriptor of the interchemical variability in K SA. Further study showed that K OA-based Karickhoff-type equations can perfectly fit experimental K SA-values. [Copyright &y& Elsevier]