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MOLECULAR COMPOSITION OF ORGANICS IN PM 2.5 AT THE NEW YORK CITY SUPERSITE WINTER 2004
Citation:
LI, M., M. MAZUREK, S. R. MCDOW, J. SCHWAB, K. DEMERJIAN, AND D. FELTON. MOLECULAR COMPOSITION OF ORGANICS IN PM 2.5 AT THE NEW YORK CITY SUPERSITE WINTER 2004. Presented at American Association of Aerosol Research 2005, Atlanta, GA, February 07 - 11, 2005.
Impact/Purpose:
1) Develop a TOA protocol that meets the basic assumptions of the method and peer review of the method, 2) understand the role of sampling, analysis, and blank subtraction on the differences between the IMPROVE and STN OC and EC results 3) Evaluate the use of light absorbance methods to estimate EC on human exposure samples, 4) develop a sensitive analytical method suitable for analysis of STN and micro-environmental samples for organic molecular markers, and 5) develop an optimum list of organic molecular markers for source apportionment of particulate matter.
Description:
Organic compounds in PM2.5 were studied at the New York City Supersite at Queens College, NYC as part of the NYC Supersite Winter 2004 Intensive from January 15 to February 5, 2004. The Queens fine particle samples were collected on a daily basis. Eight composites containing 3 to 4 filters were generated to provide sufficient organic carbon (OC) mass for the determination of individual organic molecular tracers within the OC fraction. A field blank composite (extracted exactly as the ambient PM2.5 filters) and a trip blank composite were analyzed to monitor sampling and analytical background levels of the OC molecular constituents. The filter composites were extracted with organic solvent (1:1 methylene chloride:acetone) and analyzed for 52 molecular marker compounds by gas chromatography/ion trap mass spectrometry (GC/IT MS). Normal alkanes (C25 to C32), n-alkanoic acids (C10 to C30), dicarboxylic acids (C3 to C9) and hopanes (C27 to C32) were identified in most sample composites. Ambient mass concentrations for these molecular marker groups were determined. Ratios of the ambient mass concentrations of the molecular markers to the EC and the OC fractions were established to study wintertime variation of urban emission sources in the metropolitan New York City area. Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.