A study to characterize particulate matter emissions from 195 in-use gasoline and diesel passenger vehicles was conducted during the summer of 1996 and the winter of 1997 in the Denver, Colorado region. Vehicles were tested as received on chassis dynamometers using the Federal Test Procedure (FTP) Urban Dynamometer Driving Schedule (UDDS). Both PM-10 and regulated emissions were measured for each phase of the UDDS. Approximately 88% of the PM-10 collected was carbonaceous material, of which the average organic fraction was 0.7 for gasoline vehicles and 0.4 for diesel vehicles. This suggests that the organic carbon (OC) to elemental carbon (EC) split may be useful in separating light-duty gasoline from diesel PM emissions. Sulfate emission rates averaged 0.45 and 3.51 mg/mi for gasoline and diesel vehicles, indicating that the EPA's mobile emissions model overpredicts sulfate emission rates. Elements identified by X-ray fluorescence averaged between 3 and 9% of the PM-10 mass. Polynuclear aromatic hydrocarbon (PAH) profiles developed may help distinguish between gasoline and diesel vehicles in source apportionment studies. Total PAH emissions, however, were not a good candidate as a tracer of gasoline PM emissions. Hopane and sterane emissions were very similar across the fleet and may be useful tracers for mobile source PM emissions. Overall, emission rates varied significantly with vehicle classification and driving condition, suggesting that a single profile representing the entire fleet will need to carefully reflect the local fleet composition and the local weighting of cold, hot, and hot-stabilized emissions.

Twenty-four properly functioning and six high carbon monoxide emission light-duty gasoline vehicles were emission tested in Denver, CO, using the Federal Test Procedure (FTP), a hot start Unified Cycle (UC), and the REP05 driving cycles at 35 degrees F. All were 1990-1997 model year vehicles tested on both an oxygenated and a nonoxygenated fuel. PM10 emission rates for the properly functioning vehicles using oxygenated fuel averaged 6.1, 3.6, and 12.7 mg/mi for the FTP, UC, and REP05, respectively. The corresponding values for the high emitters were 52, 28, and 24 mg/mi. Use of oxygenated fuel significantly reduces PM10 on the FTP, with all the reduction occurring during the cold start. MOUDI impactor samples showed that 33 and 69% of the PM mass was smaller than 0.1 microm for the FTP and REP05 cycles, respectively, when collected under standard laboratory conditions. Particle number counts were much higher on the REP05 than the FTP. Counts were obtained using secondary dilution of samples drawn from the standard dilution tunnel. FTP PM10 was mostly carbonaceous material, 36% of which was classified as organic. For the REP05, as much as 20% of the PM10 was sulfate and associated water. Forty-five percent of the REP05 PM carbon emissions was classified as organic. Driving cycle had a significant impact on the distribution of the emitted polynuclear aromatic hydrocarbons.

A study of particulate matter (PM) emissions from in-use, light-duty vehicles was conducted during the summer of 1996 and the winter of 1997 in the Denver, CO, region. Vehicles were tested as received on chassis dynamometers on the Federal Test Procedure Urban Dynamometer Driving Schedule (UDDS) and the IM240 driving schedule. Both PM 10 and regulated emissions were measured for each phase of the UDDS. For the summer portion of the study, 92 gasoline vehicles, 10 diesel vehicles, and 9 gasoline vehicles with visible smoke emissions were tested once. For the winter, 56 gasoline vehicles, 12 diesel vehicles, and 15 gasoline vehicles with visible smoke were tested twice, once indoors at 60 °F and once outdoors at the prevailing temperature. Vehicle model year ranged from 1966 to 1996. Impactor particle size distributions were obtained on a subset of vehicles. Continuous estimates of the particle number emissions were obtained with an electrical aerosol analyzer. This data set is being provided to the Northern Front Range Air Quality Study program and to the State of Colorado and the U.S. Environmental Protection Agency for use in updating emissions inventories.

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SummaryTwo groups of mafic dikes occur within a terrain of metasomatic granitic rocks and quartzofeldspathic gneiss in the central Bighorn Mountains of Wyoming. The younger group consists of dolerite dikes which possess ophitic, subophitic, hypidio morphic-granular and microporphyritic textures. Mineralogically, the dolerites consist primarily of plagioclase (average An 54), augite (average Ca: Mg: Fe = 41: 43: 16) and uralite. The older dikes are metadolerites which possess granoblastic margins that grade into interiors characterized by relict subophitic and locally, porphyriti texture. Dike margins consist of fresh plagioclase and hornblende primarily. Interiors are principally clouded plagioclase (average An 46), augite (average Ca: Mg: Fe = 39: 54: 7) and uralite and/or hornblende. Textural, mineralogic and chemical data indicate that the meta-dolerites were derived from an earlier generation of mafic dikes comparable to the unmeta-morphosed dolerites in the area. The dikes were metamorphosed under low amphibolite facies conditions during the last regional metamorphic event which affected the country rock. During their metamorphism, minimal amounts of water from the country rock facilitated the total recrystallization of the metadolerite margins and the complete or nearly complete replacement of pyroxene by hornblende in the margins. In general, dike interiors underwent no textural changes other than partial destruction of the original subophitic plagioclase–pyroxene relationship as the pyroxene was replaced peripherally by hornblende. This process was accompanied by diffusion of calcium from the plagioclase to form the hornblende, and by diffusion of iron from the augite to cause the clouding of adjacent plagioclase.