Identification of sources of aerosol in Chicago by chemical element mass balance

Abstract

A chemical element mass balance (CEB) receptor model was used to determine the contributions from coal combustion, cement and limestone, mobile sources, refuse incineration, soil and steel industries to the ambient particulate matter in Chicago. Twenty four hout average measurements were made of inhalable particulate (IP) matter consisting of fine particles (FP) diameter < 2.5 μm and coarse particles (CP) diameter > 2.5 μm but < 15 μm; sulfur (as SO4) and the concentration of Al, Br, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Se, Si, Ti, V and Zn for both fractions; and SO2, temperature, wind speed and wind direction on 17 days during a 4 month period from May to August 1984. The CEB was applied as an independent analysis to each sampling day. The average FP, CP and IP concentrations were 21.0 μg/m3, 28.4 μg/m3 and 49.4 μg/m3 respectively. Based on study period average, coal, limestone, mobile, refuse, soil and steel contributes 0.40 μg/m3, 7.7 μg/m3, 5.1 μg/m3, 7.8 μg/m3, 5.5 μg/m3 and 1.2 μg/m3 of the IP respectively. The contribution from the unexplained particulate matter were 16.3 μg/m3, 5.9 μg/m3 and 21.6 μg/m3 for the FP, CP and IP respectively. This suggests that the aerosol is concentrated in the small size fractions contributes by the secondary pollutants. On average, the model was able to explain 22.2%, 79.3% and 56.3% of the FP, CP and IP respectively for the Chicago site.