This report describes the technical progress made on the Pittsburgh Air Quality Study (PAQS) during the period of September 2004 through February 2005. Significant progress was made this project period on the analysis of ambient data, source apportionment, and deterministic modeling activities. The major experimental achievement this project period was the characterization of the mercury and fine particle emissions from two modern, large, commercial pulverized coal boilers. This testing completes the field work component of the Source Characterization Activity. This report highlights results from mercury emission measurements made using a dilution sampler. The measurements clearly indicate that mercury is being transformed from an oxidized to an elemental state within the dilution. This report highlights results from mercury emission measurements made using a dilution sampler. The measurements clearly indicate that mercury is being transformed from an oxidized to an elemental state within the dilution. This report also presents results from an analysis that uses spherical aluminum silicate (SAS) particles as a marker for primary PM2.5 emitted from coal combustion. Primary emissions from coal combustion contribute only a small fraction of the PM2.5 mass (less than 1.5% in the summer and less than 3% in the winter) at the Pittsburgh site. This report also presents results from applying the Unmix and PMF models to estimate the contribution of different sources to the PM2.5 mass concentrations in Pittsburgh using aerosol composition information. Comparison of the two models shows similar source composition and contribution for five factors: crustal material, nitrate, an Fe, Mn, and Zn factor, specialty steel production, and a cadmium factor. PMF found several additional factors.
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