Chemical Speciation of PM_(2.5) and PM_(10) in South Phoenix, AZ

摘要

Phoenix, AZ, experiences high particulate matter (PM) episodes, especially in the wintertime. The spatial variation of the PM concentrations and resulting differences in exposure is of particular concern. In this study, PM_(2.5) (PM with aerodynamic diameter <2.5μm) and PM_(10) (PM with aerodynamic diameter <10 μm) samples were collected simultaneously from the east and west sides of South Phoenix and at a control site in Tempe and analyzed for trace elements and bulk elemental and organic carbon. Measurements showed that although PM_(2.5) concentrations had similar trends in temporal scale across all sites, concentrations of PM_(10) did not. The difference in PM_(10) concentrations and fluctuation across the three sites suggest effects of a local soil source as evidenced by high concentrations of Al, Ca, and Fe in PM_(10). K and anthropogenic elements (e.g., Cu, Pb, and Zn) in PM_(2.5) samples on January 1 were strikingly high, suggesting the influence of New Year's fireworks. Concentrations of toxic elements (e.g., Pb) in the study presented here are not different from similar studies in other U.S. cities. Application of principal component analysis indicated two broad categories of emission sources-soil and combustion-together accounting for 80 and 90% of variance, respectively, in PM_(2.5) and PM_(10). The soil and combustion components explained approximately 60 and 30% of the variance in PM_(10), respectively, whereas combustion sources dominated PM_(2.5) (>50% variance). Many elements associated with anthropogenic sources were highly enriched, with enrichment factors in PM_(2.5) an order of magnitude higher than in PM_(10) relative to surface soil composition in the study area.