Envlron. Scl. Technol. zyxwvuts 1991, 25, 1311-1325 article has been funded in part by the zyxwvutsrqp U.S. Environmental Protection Agency under Assistance Agreement R-815709 to Montana State University through the Hazardous Substance Research Center for zyxwvutsrq US. EPA regions 7 and zyxwvutsrq 8 headquartered at Kansas State University, it zyxwvutsrqp has not been subjected to the Agency’s peer and administrative review and, therefore, may not necessarily reflect the views of the Agency, and no official endorsement should be inferred. This research was also sup- ported by the US. Geological Survey (Project zyx 14-08-0001- G1284). Quantitative Characterization of Urban Sources of Organic Aerosol by High-Resolution Gas Chromatography Lynn M. Hlldemann,?Monica A. Mazurek,s and Glen R. Caw” Environmental Engineerlng Science Department and Environmental Quality Laboratory, California Institute of Technology, Pasadena, California zyxwvuts 91125 Bernd R. T. Slmonelt College of Oceanography, Oregon State University, Corvallis, Oregon 9733 1 ~ ~~~~ ~~ ~ ~ ~ Fine aerosol emissions have been collected from a va- riety of urban combustion sources, including an industrial boiler, a fireplace, automobiles, diesel trucks, gas-fired home appliances, and meat cooking operations, by use of a dilution sampling system. Other sampling techniques have been utilized to collect fine aerosol samples of paved road dust, brake wear, tire wear, cigarette smoke, tar pot emissions, and vegetative detritus. The organic matter contained in each of these samples has been analyzed via high-resolution gas chromatography. By use of a simple computational approach, a quantitative, 50-parameter characterization of the elutable fine organic aerosol emitted from each source type has been determined. The organic mass distribution fingerprints obtained by this approach are shown to differ significantly from each other for most of the source types tested, using hierarchical cluster analysis. Introduction Most of the existing data on organic aerosol emissions from sources are derived from bulk chemical analyses that quantify the total amount of organic carbon present. Total aerosol emissions of organic carbon have been measured by combustion techniques for a large variety of sources (e.g., refs 1 and 2). Gravimetric procedures have been used to quantify the amount of extractable organic material emitted from sources such as boilers (e.g., refs zyxwvut 3-5), motor vehicles (e.g., refs 6-9), and fireplaces (e.g., refs 10 and 11). Some separation of the organic species based on vapori- zation temperature also has been achieved by using thermal evolution analysis to produce “thermograms” (12-17). These approaches provide little or no information about the underlying molecular structure of the organic aerosol compounds emitted. Other researchers have used costly, time-consuming procedures to identify specific organic compounds (e.g., polycyclic aromatic hydrocarbons) through approaches such as gas chromatography coupled with mass spectrom- etry (GC/MS) and high-pressure liquid chromatography with fluorescence detection. Daisey and co-workers (18) have published a thorough review of the literature between 1972 and 1986 that identifies specific organic compounds in various source emissions. The individual compounds identified typically account for only a few percent of the ‘Present address: Department of Civil Engineering, Stanford t Present address: Environmental Chemistry Division, Bldg. 426, University, Stanford, CA 94305-4020. Brookhaven National Laboratory, Upton, NY 11973. total organic mass emitted. Hence these data are of limited use in designing pollution abatement programs that must achieve changes in the total amount of aerosol present. Aerosol carbon emissions arise from a large number of different source types. Recent studies of Los Angeles (19, 20) have shown that at least a dozen different source types must be considered in order to account for close to 80% of the primary organic aerosol emissions in that airshed. To determine the effect of these emission sources on am- bient air quality via receptor modeling techniques, at the very least there must be more distinctive attributes of the organic aerosol than there are different source types. The predictions of transport-oriented models in relating source contributions to the ambient organic aerosol likewise re- quire detailed characterization of the emission sources for model verification. In both air quality modeling ap- proaches, a procedure is needed for characterizing the organic aerosol emission sources that is more economical than GC/MS analysis, but provides a fuller description of the differences between the source types than is possible from bulk carbon analysis. In the present study, gas chromatography (GC) analyses alone are used to characterize the organic aerosol emissions from a variety of sources in a way that reveals the dis- tinctive features of the different source types using a quantitative, multiparameter description. This approach shows promise as a tool for characterizing organic emissions in a way that can be used to better support air quality modeling studies. Experimental Section Sample Collection. Fine organic aerosol (particle di- ameter d, C 2 ,urn) was collected from combustion sources by a dilution stack sampling system, and other sources were sampled by grab sampling techniques. The source types tested and the number of samples analyzed are itemized in Table I. Details of the sampling procedures used for each of the sources have been described elsewhere (191, and the design of the stack sampler has been docu- mented previously (21). Briefly, hot stack gases were diluted many-fold with purified dilution air that had passed through an activated carbon bed and an absolute filter. During the dilution process, the source effluent was cooled to ambient tem- perature and kept at near-ambient pressure, causing the aerosol-forming organic vapors present to condense onto preexisting aerosol as would normally occur in the plume downwind of the stack. The diluted emissions passed through a 2-pm size-cut cyclone, and the fine particulate 0013-936X/91/0925-1311$02.50/0 @ 1991 American Chemical Soclety Environ. Sci. Technol., Vol. 25, No. 7, 1991 1311