Gas-particle partitioning and behavior of dioxin-like PCBs in the urban atmosphere of Gyeonggi-do, South Korea

To evaluate their behavior and gas-particle partitioning, the concentrations of dioxin-like polychlorinated biphenyls (dl-PCBs) in both gas and particle phases in ambient air were measured at urban sites in Gyeonggi-do, South Korea. The predominance of gas-phase PCBs in the atmosphere was more significant during summer at all sites. In July, approximately 92% of the total toxic equivalent quantity (TEQ) was in the gaseous phase, whereas in January, approximately 96% of the total TEQ was in the particle phase. The dl-PCBs can be transported over long ranges and accumulate rapidly in plants at warm temperatures. Partial vapor pressures of dl-PCBs were well correlated with temperature and the steep slopes obtained from Clausius-Clapeyron plots indicated that the volatilization of dl-PCBs from surfaces in the local surroundings of the sampling sites dominated the atmospheric concentrations. The gas-particle distribution was also examined through several different approaches such as the log K-P-log P-L(O), log K-P-log K-OA, Junge-Pankow, and K-OA-based models. The slopes obtained from regressing log K-P versus log P-L(O) (log K-P versus log K-OA) were smaller than - 1 (or 1). The particle-bound fraction (phi) and K-P of the dl-PCB congeners were estimated using the Junge-Pankow and K-OA-based models. Both models tended to overestimate the phi and K-P values of the dl-PCB congeners compared to those obtained from field measurements. Nevertheless, the coefficients of determination (r(2)) between the experimental and modeled K-P values were 0.74 to 0.84 and 0.76 to 0.84 for the Junge-Pankow and K-OA-based models, respectively. (C) 2011 Elsevier By. All rights reserved.