Snowmobile exhaust emissions in the snowpack of Yellowstone National Park

Abstract

The use of snowmobiles within national park boundaries is a source of intense controversy. Exhaust emission levels of two-stroke engines used in snowmobiles are high in comparison to four-stroke engines, with as much as 30% of the fresh air-fuel mixture exiting the cylinder with the exhaust stream. In May of 1997, The Fund for Animals, Biodiversity Legal Foundation, Predator Project, Ecology Center, and five individuals filed suit against the National Park Service for failure to comply with the National Environmental Policy Act (NEPA), the Endangered Species Act (ESA), and other federal laws and regulations in connection with winter use in the three national parks. As a result, many investigations were initiated addressing issues such as air quality, exhaust emission levels in the snowpack due to snowmobiles, and emission reduction methods for snowmobiles. The purpose of this Masters thesis is to determine the levels of snowmobile exhaust products in the West Yellowstone snowpack. This research in combination with other completed and on-going investigations will determine the environmental impact of snowmobiles upon the West Yellowstone ecosystem. Analysis of snow samples was performed with a modified version of EPA method 525.2 originally developed for the determination of organic compounds in drinking water by liquid-solid extraction and GC/MS. N-Alkanes C15-22 were detected at concentrations of 0.2-3.7ppm in the snow. Organic Acids C-12,14,16, and 18 were also detected in the snow samples. Three PAH compounds were detected in the snow samples. fluorene and phenanthrene were identified at concentrations of 10-200ppt, and naphthalene was detected at concentrations of 5-25ppb. Data indicates that contamination is localized to the road with snowmobiles being the primary contributor to hydrocarbon contamination of the snowpack. The concentration of all analytes was observed to decrease rapidly with distance from the road. The concentration of N-Alkanes C15-22 decreased an average of 89% and Organic Acids C-12,14,16, and 18 decreased an average of 90%within 50 feet of the road. PAH concentrations were also noted to decrease with distance from the road.