Effects of temperature and relative humidity on soil−air partition coefficients of organophosphate flame retardants and polybrominated diphenyl ethers

Abstract

The soil−air partition coefficients (KSA) of polybrominated diphenyl ethers (PBDEs) and organophosphate flame retardants (OPFRs) is important for determining their fate in soil and air media. However, KSA values of OPFRs and PBDEs are not available from the current literature, and the effects of environmental factors such as temperature and relative humidity (RH) on KSA values are not clear. In this study, a solid-phase fugacity meter was used to measure the KSA values of PBDEs and OPFRs at different temperatures (25, 30, 35, 40, and 45 °C) and relative humidity (RH) conditions (<3 and 100% RH), the relationships between KSA and octanol−air partition coefficients (KOA) for OPFRs and PBDEs were analyzed. The results showed that an increase in temperature and RH resulted in a decrease of all KSA values for PBDEs and OPFRs. Furthermore, the effects of RH on the soil−air partitioning behavior of PBDEs were larger than that of OPFRs. In addition, a significant correlation (p < 0.0001) was observed between log KSA and log KOA. The experimental KSA values of OPFRs and PBDEs were quite different from the predicted KSA, when calculated with their KOA values. Overall, this study provides a better understanding for predicting the behavior and fate of OPFRs and PBDEs in soil−air systems.