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CHARACTERIZATION OF AMBIENT PM2.5 AEROSOL AT A SOUTHEASTERN US SITE: FOURIER TRANSFORM INFRARED ANALYSIS OR PARTICLE PHASE
Citation:
Weathers, W S. CHARACTERIZATION OF AMBIENT PM2.5 AEROSOL AT A SOUTHEASTERN US SITE: FOURIER TRANSFORM INFRARED ANALYSIS OR PARTICLE PHASE. Presented at American Association of Aerosol Research, Charlotte, NC, October 7-11, 2002.
Impact/Purpose:
1. Using laboratory and field study data generated during FY99-FY04, develop a science version of a PM chemistry model for predicting ambient concentrations of water, inorganics, and organics in PM2.5 samples. The model will include the Aerosol Inorganic Model for predicting concentrations of inorganic compounds and a computational chemistry-based method for predicting concentrations of organic compounds.
2. Identify and evaluate methods for analyzing the polar fraction of PM2.5 samples.
3. Carry out short term field studies in Research Triangle Park, North Carolina in the summer and the winter to determine the composition of the organic fraction of ambient PM2.5 samples, with special emphasis placed on identifying and determining ambient concentrations of polar compounds.
4. Conduct laboratory studies to establish the chemical composition of secondary organic aerosol (SOA) and to determine source signatures for aromatic and biogenic SOA.
5. Conduct laboratory and theoretical investigations of thermodynamic properties of polar organic compounds.
6. Evaluate the science version of the PM chemistry model using laboratory and field data generated under this task as well as other available data in the literature.
7. Conduct PM chemistry-related special studies for OAQPS
Description:
During a field study in the summer of 2000 in the Research Triangle Park (RTP), aerosol samples were collected using a five stage cascade impactor and subsequently analyzed using Fourier Transform Infrared Spectroscopy (FTIR). The impaction surfaces were stainless steel disks. The FTIR analysis involved a unique technique in which the impactor disks were examined, first, by reflectance, followed by attenuated total reflectance (ATR) analysis of solvent extracts of the deposits on the disks. In the ATR analysis, each disk was rinsed with a few microliters of hexane, acetone, ethanol, and water, respectively. Each solvent rinse was added to a horizontal ATR where the solvent was allowed to dry and the residue analyzed. Results from the study of the aerosol at this site show that the aerosol consists overwhelmingly of polar constituents. Carbonyls were a major constituent of the organic fraction while ammonium sulfate predominated in the inorganic fraction of the aerosol. This poster presentation will explain the analysis procedure in detail and will report on the results of the 2000 field study.
This work has been funded wholly by the United States Environmental Protection Agency. It has been subject to Agency review and approved for publication.