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Published May 15, 1999 | public
Journal Article

Measurement of Emissions from Air Pollution Sources. 2. C_1 through C_(30) Organic Compounds from Medium Duty Diesel Trucks


Gas- and particle-phase tailpipe emissions from late-model medium duty diesel trucks are quantified using a two-stage dilution source sampling system. The diesel trucks are driven through the hot-start Federal Test Procedure (FTP) urban driving cycle on a transient chassis dynamometer. Emission rates of 52 gas-phase volatile hydrocarbons, 67 semivolatile and 28 particle-phase organic compounds, and 26 carbonyls are quantified along with fine particle mass and chemical composition. When all C_1−C_(13) carbonyls are combined, they account for 60% of the gas-phase organic compound mass emissions. Fine particulate matter emission rates and chemical composition are quantified simultaneously by two methods:  a denuder/filter/PUF sampler and a traditional filter sampler. Both sampling techniques yield the same elemental carbon emission rate of 56 mg km^(-1) driven, but the particulate organic carbon emission rate determined by the denuder-based sampling technique is found to be 35% lower than the organic carbon mass collected by the traditional filter-based sampling technique due to a positive vapor-phase sorption artifact that affects the traditional filter sampling technique. The distribution of organic compounds in the diesel fuel used in this study is compared to the distribution of these compounds in the vehicle exhaust. Significant enrichment in the ratio of unsubstituted polycyclic aromatic hydrocarbons (PAH) to their methyl- and dimethyl-substituted homologues is observed in the tailpipe emissions relative to the fuel. Isoprenoids and tricyclic terpanes are quantified in the semivolatile organics emitted from diesel vehicles. When used in conjunction with data on the hopanes, steranes, and elemental carbon emitted, the isoprenoids and the tricyclic terpanes may help trace the presence of diesel exhaust in atmospheric samples.

Additional Information

© 1999 American Chemical Society. Received for review January 27, 1998. Revised manuscript received January 19, 1999. Accepted February 4, 1999. We thank Rapheal Susnowitz, Thu Vo, Pons Lazo, and the staff at the California Air Resources Board's Haagen-Smit Laboratory in El Monte, CA, for their assistance and cooperation in conducting the diesel truck source tests, Eric Grosjean and Daniel Grosjean (DGA, Inc.) for preparation and analysis the C_(18) cartridges used for carbonyls, Rei Rasmussen (Oregon Graduate Institute) for preparation and analysis of the SUMA canisters used for measurement of C10 and smaller vapor-phase hydrocarbons, Judy Chow and Cliff Frazier at the Desert Research Institute for X-ray fluorescence measurements, Bob Cary at Sunset Labs for EC/OC measurements, and Lynn Salmon (Caltech) for conducting the ion chromatography and atomic absorption spectroscopy analyses. This research was supported by the California Air Resources Board under Agreement number A93-329.

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