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PM2.5 Organic Composition from Several Sites in the United States

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Abstract: Organic constituents make up an important component of fine particulate matter (PM2.5) in ambient environments. While part of the composition of organic aerosol results from emissions of primary sources, an additional component appears to come from gas-to-particle conversion of photooxidation products of natural and anthropogenic hydrocarbons. These secondary products have been measured in simulated atmospheres in this and other laboratories. However, except under specialized circumstances, many of the oxidation products of anthropogenic origin are rarely reported in the fine particle fraction of ambient aerosols.

A study was conducted to examine the summertime composition of PM2.5 at four locations along the Mid-Atlantic portion of the United States: a semi-rural field site in Research Triangle Park, North Carolina and urban sites in Baltimore, Maryland, Philadelphia, Pennsylvania, and New York, New York. Measurements were made for the inorganic and organic constituents of the fine particulate mass. Detailed analysis of the organic carbon was also undertaken using a double derivatization technique with PFBHA for the derivatization of carbonyl groups and BSTFA for hydroxyl groups. Inorganic ion (sulfate and nitrate) measurements, liquid water, and gravimetric measurements were also made from an aerosol collections on Teflon filters. Organic and elemental carbon were measured using a thermo-optical technique from aerosol collections onto quartz filters.

The study was carried out over a three week period from 10 July - 02 August 2001. Samples for seven 24-hour and four 48-hour sampling periods were taken. Gravimetric results indicated that total mass loadings ranged from 5.7 to 42 ?g m-3 for the sampling periods during that time frame. At the rural site, the organic mass was estimated to comprise 57% of the total gravimetric mass. By contrast, at the urban site on average, the organic mass was estimated to comprise 32% of the total mass. The detailed analysis of the organic fraction from each of the urban sites showed chemical markers related to photooxidation products of aromatic hydrocarbons; oxygenated products from the rural site indicated the presence of biogenic precursors. In general, the aerosol was highly oxygenated and a wide range of substituted diacids appeared to be some of the dominant compounds found by this analysis approach.

This work has been funded fully, or in part, by the United States Environmental Protection Agency, under Contract Number 68-D5-0049 to ManTech Environmental Technology, Inc. It has been subjected to Agency review and approved for publication.
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Citation:Edney, E. O., R. E. Speerand, W. S. Weathers, T. E. Kleindienst, E. W. Corse, and C. D. Mciver. PM2.5 Organic Composition from Several Sites in the United States. Presented at American Association for Aerosol Research, Charlotte, Nc, October 7-11, 2002.
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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: Atomospheric Chemistry & Physics Branch
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Product Type: Abstrct/Oral
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Presented: 10/07/2002
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Related Entries:
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Bullet Item Science Version of PM Chemistry Model
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Last Updated on Monday, October 22, 2007
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