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CHARACTERIZATION OF PARTICULATE MATTER FROM PHOENIX, ARIZONA, USING RAY FLUORESCENCE AND COMPUTER-CONTROLLED SCANNING ELECTRON MICROSCOPY
Citation:
Norris, G A., T L. Conner, M S. Landis, AND R B. Zweidinger. CHARACTERIZATION OF PARTICULATE MATTER FROM PHOENIX, ARIZONA, USING RAY FLUORESCENCE AND COMPUTER-CONTROLLED SCANNING ELECTRON MICROSCOPY. Presented at Third Colloquium on Particulate Matter and Human Health, Chapel Hill, NC, June 6-8, 1999.
Description:
Numerous epidemiological studies have found associations between airborne particulate matter measured at community monitors and increased mortality and morbidity. Chemical and physical characteristics of particulate matter (e.g., elemental composition, size) and source identification are required to help understand the observed health associations and to provide information for particulate matter toxicology studies. The sources and composition of particulate matter in Phoenix, Arizona were investigated by analyzing PM2.5 and PM10-2.5 filters with energy dispersive x-ray fluorescence (XRF) and scanning electron microscopy with energy dispersive x-ray fluorescence (SEM/EDX). Samples used in this analysis were from the EPA National Exposure Research Platform in central Phoenix, which collected dichotomous samples every third day and PM2.5 samples every day for 3 years. This study analyzed a subset of the PM10-2.5 samples from a modified dichotomous sampler (VAPS) which has approximately 10 percent of the PM2.5 fraction on the PM10-2.5 sample. A subset of samples was evaluated using SEM/EDX in the manual mode. Computer-Controlled Scanning Electron Microscopy (CCSEM) was applied to two of the samples representing two different air masses. CCSEM allows unattended analysis of particle size, shape, and chemistry. Particle classification rules were developed for the PM2.5 and PM10-2.5 fractions and applied to the CCSEM data. Factor analyses of the PM2.5 and PM10-2.5 XRF elemental concentrations were compared to SEM/EDX results to show the benefit of evaluating samples with SEM/EDX. In addition, back trajectory analysis was used to evaluate the SEM/EDX and XRF results.
This paper has been reviewed in accordance with the U.S. Environmental Protection Agency's peer and administative review policies and approved for presentation. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.