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 investigate atmospheric scavenging of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). Particle scavenging was the dominant contributor to the total concentrations in snow and was less important in rain. Gas scavenging was only important for low molecular weight PCB congeners and PAHs. Enrichment of dissolved-phase concentrations over levels predicted from temperature-corrected Henry's Law constants was observed for low molecular weight compounds in both rain and snow. The particulate fraction (φ) of atmospheric PCBs and PAHs was the best indicator of total scavenging ( W T ) by snow according to the equations log W T = 0.71 (±0.08) log φ + 5.34 (±0.08) for PCB congeners ( r = 0.62) and log W T = 0.89 (±0.12) log φ + 6.07 (±0.13) for PAHs ( r = 0.73).