SNOW SCAVENGING OF POLYCHLORINATED-BIPHENYLS AND POLYCYCLIC AROMATIC-HYDROCARBONS IN MINNESOTA

Snow and rain events were collected with concurrent air samples during the winter of 1991-1992 at a suburban site in Minnesota to investigat e atmospheric scavenging of polychlorinated biphenyls (PCBs) and polyc yclic aromatic hydrocarbons (PAHs). Particle scavenging was the domina nt contributor to the total concentrations in snow and was less import ant in rain. Gas scavenging was only important for low molecular weigh t PCB congeners and PAHs. Enrichment of dissolved-phase concentrations over levels predicted from temperature-corrected Henry's Law constant s was observed for low molecular weight compounds in both rain and sno w. The particulate fraction (phi) of atmospheric PCBs and PAHs was the best indicator of total scavenging ( W-T) by snow according to the eq uations log W-T = 0.71 (+/-0.08) log phi + 5.34 (+/-0.08) for PCB cong eners (r= 0.62) and log W-T = 0.89 (+/-0.12) log phi + 6.07 (+/-0.13) for PAHs (r= 0.73).