Characterization of metal aerosols in PM10 from urban, industrial, and Asian Dust sources.

Metallic elements (As, Be, Ca, Cd, Co, Cr, Fe, K, Mn, Ni, Pb, Sb, Se, and Zn) in PM10 aerosols were determined at urban and industrial sites, which are affected by traffic and residential sources, metallurgical activity, and petrochemical and steel works. The effect of the long-range transported Asian Dust on the metal content of aerosols was also examined. At the urban sampling site, concentrations of As, Cd, Pb, Se, and Zn were assigned to road traffic and combustion sources, Ca and Fe to soil dust sources from long-range transported Asian Dusts, and Cr and Ni to metallurgical sources transported from the nearby industrial complex, based on Principal Component Analysis (PCA). Enhanced Cr and Ni concentrations at the metallurgical industrial site suggest that local emissions from metal-assembly facilities and manufacture of alloys contributed to elevated levels of those metals. We also observed that petrochemical activities contributed to increased levels of Sb and Zn. When Asian Dust events occurred, Ca, Fe, K, and Zn concentrations dramatically increased compared to values without the Asian Dust. Two different types of Asian Dust events were observed. For the Asian Dust event 1 (4/1/2007), the Fe and K concentrations were much higher by a factor of 2-3 than those for the Asian Dust event 2 (3/2/2008), while As, Mn, and Zn concentrations were significantly higher on the Asian Dust event 2. Backward trajectory analysis showed that for the Asian Dust event 2, the air mass had passed over the heavily industrialized zones in China during long-range transport to the current sampling site, suggesting that the As, Mn, and Zn may have originated from industrial sources.