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PM 2.5 CHEMICAL SPECIATION SAMPLER EVALUATION FIELD PROGRAM: RESULTS FROM THE FOUR CITY STUDY
Citation:
Solomon, P A., W J. Mitchell, D B. Gemmill, M P. Tolocka, R W. Wiener, S. I. Eberly, J. Rice, J. P. Homolya, AND A. H. Miguel. PM 2.5 CHEMICAL SPECIATION SAMPLER EVALUATION FIELD PROGRAM: RESULTS FROM THE FOUR CITY STUDY. Presented at American Association for Aerosol Science, Tacoma, WA, October 11-15, 1999.
Description:
The objective of this sampler intercomparison field study is to determine the performance characteristics for the collection of the chemical components of PM2.5 by the chemical speciation monitors developed for the national network relative to each other, to the Federal Reference Method (FRM), and to other historically accepted monitors. While the FRM is the standard for mass, there are no such standards for the chemical components of PM2.5. Thus, this intercomparison will establish which methods are equivalent to each other on a species by species basis. For volatile species (e.g., ammonium nitrate and semi-volatile organic compounds), the FRM provides only a lower limit on the expected mass loading for that species, as there is potential for loss of these species from the inert Teflon filters. For stable species, the FRM should provide an accurate estimate of the mass loading for those species. The historical samplers will provide an additional set of samples for comparison; however, they still can only be compared on an equivalent basis as none represent a reference method sampler.
The chemical speciation monitors have been developed and manufactured by three vendors under the National PM Sampler procurement, the need for which was described under 40 CFR, Part 58, Appendix C. The three samplers are the Reference Ambient Air Sampler (RAAS) developed by Andersen, Mass Aerosol Speciation Sampler (MASS) developed by University Research Glassware (URG), and Spiral Ambient Speciation Sampler (SASS) developed by MetOne. Two FRM samplers were operated at each site and collected aerosol samples on Teflon and quartz-fiber filters to allow for chemical characterization, similar to the chemical speciation monitors. Historically accepted methods include the IMPROVE sampler, the Versatile Air Pollution Sampler, and the South Coast Air Quality Management District's PTEMP sampler. Chemical characterization included, sulfate, nitrate, ammonium, and chloride by ion chromatography, elements by XRF, OC/EC by TOR, and mass by gravimetric analysis. Appropriate filter media were used to allow for chemical analysis by these routine methods. Because of statistical and practical considerations, four locations were chosen: Philadelphia, PA, Phoenix, AZ, Rubidoux, CA, and Research Triangle Park, NC. Statistical analysis of the data involved comparisons among the different samplers to examine differences in the determined chemical components due to sampler design characteristics. The results of this limited four-city intercomparison study will be presented and eventual differences found among the samplers discussed in light of known aerosol collection processes and site characteristics.
This work has been funded wholly or in part by the United States Environmental Protection Agency. Portions of the work were performed under Contract No. 68-D5-0040 by Research Triangle Institute. It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.