A Determination 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 contnbutions from coal combustion, cement and limestone, mobile sources, refuse incineration, soil, and steel industries to the ambient particulate matter in Chicago. Twenty-four hour average measurement were made of inhalable particulate (IP) matter consisting of fine particles (FP) diameter < 2.5 μm and coarse particles (CP) diamerer > 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 size 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 JP 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.