Ambient Aerosol Concentrations of Elements Resolved by Size and by Source:  Contributions of Some Cytokine-Active Metals from Coal- and Oil-Fired Power Plants

Size-segregated aerosol samples were collected with Micro-Orifice Impactors in Baltimore, MD, a typical northeastern port city where air quality is influenced by urban and industrial sources. The size fractions were analyzed for up to 32 elements by Instrumental Neutron Activation Analysis and the results were used in a chemical mass balance model to resolve the contributions to ambient levels by size and by source. Resolution by size improves interpretation of the results as primary accumulation aerosol populations from different sources are frequently resolved in the size spectra of their marker species. With a 15-source model, agreement between measured and predicted concentrations was within 40% for all elements except Co, Cr, Cs, Ti, and W. The results suggest that coal-fired power plants are minor sources of the respirable fractions of several metals, including Cr (19%), V (5%), and Zn (