Gas-particle partitioning of polychlorinated naphthalenes and non- and mono-ortho-substituted polychlorinated biphenyls in arctic air

Gas-particle partitioning relationships were developed for partitioning of polychlorinated naphthalenes (PCNs) and non- and mono-ortho PCBs in arctic air by regressing observed gas-particle partition coefficients, K(P), at Alert and Dunai in the high Arctic with temperature-adjusted experimental vapor pressures (p(L) degrees ) and octanol-air partition coefficients (K(OA)). Slopes were near -0.5 and 0.5 for log p(L) degrees and log K(OA), respectively, at both sites, indicating that aerosol characteristics and partitioning processes were similar at the two sites. The K(OA) absorption model provided an adequate estimate of the percentage of PCNs and non-/mono-ortho PCBs associated with particulate matter, based on fraction of organic matter (f(OM)) ranging from 0.074 to 0.12, compared to the Junge-Pankow adsorption model, which slightly over-estimated the distribution on particles. There were no indications that partitioning to soot carbon influences the observed gas-particle distribution for PCNs and non-/mono-ortho PCBs in arctic air as has been observed for PAHs in recent studies at temperate locations.

Atmospheric particle evolution during a nighttime atmospheric mercury depletion event in sub-Arctic at Kuujjuarapik/Whapmagoostui, Québec, Canada

During a field experiment at Kuujjuarapik/Whapmagoostui (55.31 degrees N, 77.75 degrees W), Quebec, we observed increases of concentrations of particles with diameters larger than 0.3 microm in the ambient air during a nighttime atmospheric mercury depletion event (AMDE). These increases were strongly correlated with decreases of ozone and atmospheric mercury, and we also observed a change in the particle size distribution during this AMDE. Assuming that these phenomena imply either a chemical link or an association through transport, we also studied the nature of this AMDE. We hypothesize that the observed AMDE was a result of an influx of already depleted air masses and that it was not a product of local chemical reactions.