Atmospheric concentration characteristics and gas/particle partitioning of PCBs from the North Pacific to the Arctic Ocean

Abstract

Polychlorinated biphenyls (PCBs) were measured in atmospheric samples collected from the North Pacific to the Arctic Ocean between July and September 2012 to study the atmospheric concentration characteristics of PCBs and their gas/particle partitioning. The mean concentration of 26 PCBs (vapor plus particulate phase) (ΣPCBs) was 19.116 pg/m3 with a standard deviation of 13.833 pg/m3. Three most abundant congeners were CB-28, −52 and −77, accounting for 43.0% to ΣPCBs. The predominance of vapor PCBs (79.0% to ΣPCBs) in the atmosphere was observed. ΣPCBs were negative correlated with the latitudes and inverse of the absolute temperature (1/T). The significant correlation for most congeners was also observed between the logarithm of gas/particle partition coefficient (logKP) and 1/T. Shallower slopes (from −0.15 to −0.46, average −0.27) were measured from the regression of the logarithm of sub-cooled liquid vapor pressures (logpL○) and logKP for all samples. The difference of the slopes and intercepts among samples was insignificant (p>0.1), implying adsorption and/or absorption processes and the aerosol composition did not differ significantly among different samples. By comparing three models, the J-P adsorption model, the octanol/air partition coefficient (KOA) based model and the soot-air model, the gas/particle partitioning of PCBs in the Arctic atmosphere was simulated more precisely by the soot-air model, and the adsorption onto elemental carbon is more sensitive than the absorption into organic matters of aerosols, especially for low-chlorinated PCB congeners.