Fine, ultrafine and nanoparticle trace element compositions near a major freeway with a high heavy-duty diesel fraction

Trace elements and metals in the ultrafine (-3), Na (129 ng m^-3), and Fe (89 ng m^-3) while S (35 ng m^-3) and Fe (35 ng m^-3) were the most abundant in the ultrafine mode. The concentrations of several trace elements, including Mg, Al, and Zn, and in particular Ca, Cu, and Pb, did not uniformly increase with size within fine PM, an indication that various roadway sources exist for these elements. Calculation of crustal enrichment factors for the two sites indicates that the freeway traffic contributed to enriched levels of ultrafine Cu, Ba, P and Fe and possibly Ca. The results of this study show that trace elements constitute a small fraction of PM mass in the nanoparticle size range, but these can and should be characterized due to their likely importance to human health. © 2007 Elsevier Ltd. All rights reserved.