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 KP–log PLo, log KP–log KOA, Junge–Pankow, and KOA-based models. The slopes obtained from regressing log KP versus log PLo (log KP versus log KOA) were smaller than − 1 (or 1). The particle-bound fraction (φ) and KP of the dl-PCB congeners were estimated using the Junge–Pankow and KOA-based models. Both models tended to overestimate the φ and KP values of the dl-PCB congeners compared to those obtained from field measurements. Nevertheless, the coefficients of determination (r2) between the experimental and modeled KP values were 0.74 to 0.84 and 0.76 to 0.84 for the Junge–Pankow and KOA-based models, respectively.

Research highlights
► The predominance of gas-phase PCBs in the atmosphere was more significant in summer.
► The particle-bound fraction (φ) and KP of the dl-PCBs congeners were estimated.
► The KP values and the correlation between log KP and log PLo were evaluated.