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East Versus West in the US: Chemical Characteristics of PM 2.5 During the Winter of 1999

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Abstract:The chemical composition of PM2.5 was investigated at four sites (Rubidoux, CA, Phoenix, AZ, Philadelphia, PA, and RTP, NC) in January and February of 1999. Three samplers were used to determine both the overall mass and the chemical composition of the aerosol. Teflon filters were weighed for total mass. Ions were analyzed using ion chromatography. Elements were determined using X-Ray fluorescence. Organic and elemental carbon were measured using a thermo-optical method. At all of the sites, reconstructed mass was observed to be greater than or equal to the measured mass. Good ionic balance was found for ammonium, nitrate and sulfate at each of the sites. Overall, the chemical composition of the aerosol for each site was in good agreement with the expected composition based upon previous studies, with the exception of relatively high nitrate contribution to the total mass at Philadelphia. Good agreement was found between the predicted amount of sulfate by XRF analysis of sulfur and the sulfate measured by ion chromatography. As expected, sulfate was a more important contributor to the total mass at the East Coast sites. Nitrate contributed more to the total mass at the west coast sites and was an important factor in the highest observed mass concentration at Rubidoux. Teflon filters appear to lose nitrate to a greater extent than heat-treated quartz fiber filters. Organic carbon was also found to be the largest part of the aerosol mass on minimum days for all sites and a significant portion of the mass on other days with 25-50% of the total mass at all of the sites. At three of the sites, OC collected on denuded filters was less than that found on non-denuded samples, indicating an absorptive artifact on the quartz fiber filters. It was also found that the crustal component to PM2.5 was highest at Phoenix. PM2.5 was also found to contribute significantly to the PM10 particle mass at all the sites.

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.
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Citation:Tolocka, M. P., P. A. Solomon, W. J. Mitchell, G. A. Norris, D. B. Gemmill, R. W. Wiener, R. W. Vanderpool, J. P. Homolya, and J. Rice. East Versus West in the US: Chemical Characteristics of PM 2.5 During the Winter of 1999. AEROSOL SCIENCE AND TECHNOLOGY 34(1):88-96, (2001).
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Contact: Liz Hope - (919) 541-2785 or hope.elizabeth@epa.gov
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Division: Human Exposure & Atmospheric Sciences Division
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Branch: Atmospheric Methods & Monitoring Branch
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Product Type: Journal
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Published: 09/05/2001
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Related Entries:
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Bullet Item Heasd PM Research Methods: Particle Methods Evaluation and Development
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