title: Snowmobile contributions to mobile source emissions in Yellowstone National Park.
abstract: Increases in the number of winter visitors to Yellowstone National Park during the past decade have raised concerns over the environmental impacts of snowmobiling in the park. During the 1998-99 season, more than 62,000 snowmobile and 1300 snow coach trips entered the park. Using the University of Denver's vehicle exhaust remote-sensing equipment, 1385 measurements of carbon monoxide (CO) and hydrocarbon (HC) emissions were collected from in-use snowmobiles at the west and south entrances to the park. Overall means of 392 +/- 4 g CO and 237 +/- 1 g HC were observed per kilogram of fuel consumed. In addition, using an ultraviolet monochromator, 460 measurements of toluene emissions were collected with a mean of 39 +/- 1 g toluene/kg of fuel. Using these data, a mobile source emissions inventory based on fuel use for Yellowstone National Park shows that snowmobiles account for 27% of the annual emissions of carbon monoxide and 77% of annual emissions of hydrocarbons using an equivalent best estimate for the summer mobile source emissions. Use of oxygenated fuels in snowmobiles was found to reduce CO emissions by 13.2 +/- 6.5% without an observed effect on HC emissions. Liquid-cooled sleds were found to have HC emissions 9.5 +/- 2.2% higher than those from fan-cooled sleds because of the increased intake and exhaust port sizes required in the larger liquid-cooled engines, which increases blowby in the 2-stroke engines.
authors.affiliation: Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, USA. gbishop@du.edu
authors.forename: G A
authors.initials: GA
authors.lastname: Bishop
authors.forename: J A
authors.initials: JA
authors.lastname: Morris
authors.forename: D H
authors.initials: DH
authors.lastname: Stedman
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002248:Carbon Monoxide / Q000032:analysis; D004784:Environmental Monitoring; D006801:Humans; D006838:Hydrocarbons / Q000032:analysis; D011998:Recreation; D012914:Snow; D001335:Vehicle Emissions / Q000032:analysis*; D014959:Wyoming
chemical_list: D000393:Air Pollutants; D006838:Hydrocarbons; D001335:Vehicle Emissions; D002248:Carbon Monoxide