PAH Deposition to Snow Surface. Chemical Analysis and Interpretation of Results

The urban snowpack effectively acts as a collection device for atmospheric-deposited PAHs. When these PAHs are flushed out in a short time interval along with springtime snowmelt, these cause shockloading to receiving waters. In order to assess the PAH deposition and accumulation in urban snowpacks, a deposition survey of PAH for the winter months of 1991-92 from the city of Sault Ste. Marie, Ontario, Canada was undertaken. The results of the survey are interpreted in view of prevailing meteorology and various emission sources in the study area. The relative PAH deposition levels (to BaP) are compared with relative source emission fingerprints to examine consistency in sampling and analysis. While analyzing the PAH samples using the ASTM (1987) method, the problem of concentration levels being below the detection level was encountered. The ASTM method for PAH analysis was modified to enhance the detection limit of the PAHs by concentrating the PAH extract to very low volumes, on the order of 200-300 microL.