USGS/DON CAMPBELL

WACAP investigators make their way into park backcountry at Sequoia and Kings Canyon national parks in midwinter to collect snow samples for airborne contaminant analysis.

TRANSPORT AND DEPOSITION OF ATMOSPHERIC CONTAMINANTS have been recognized as a possible threat to aquatic and terrestrial ecosystems for several decades. Studies in the 1970s and 1980s on air quality and acidic precipitation first demonstrated the concept of long-range transport of airborne contaminants in the United States. Numerous other airborne contaminant threats to ecosystems and humans that depend upon them were subsequently identified. The presence of contaminants in remote Arctic ecosystems with no local or watershed sources of contaminants confirmed the risk of long-range atmospheric transport. High-elevation and high-latitude areas were identified as areas of particular peril due to the tendency of contaminants, such as some pesticides, to migrate to colder alpine and Arctic areas and deposit with the annual snowpack.

Given the above concerns, as well as the persistence and toxicity of these contaminants in the environment, the bioaccumulative properties of many compounds that magnify concentrations at higher levels of the food chain, and federal legislation that requires protection of the natural parks in perpetuity, the National Park Service (NPS) conducted the multiagency Western Airborne Contaminants Assessment Project (WACAP) from 2002 to 2007 to determine the risk from airborne toxic compounds to national park ecosystems and food webs. Concentration of contaminants in air, snow, water, lake sediment, lichen, conifer needles, and fish was determined from sampling two sites/lakes in eight core park units: Denali National Park and Preserve (Alaska), Gates of the Arctic National Park and Preserve (Alaska), Glacier National Park (Montana), Mount Rainier National Park (Washington), Noatak National Preserve (Alaska), Olympic National Park (Washington), Rocky Mountain National Park (Colorado), and Sequoia and Kings Canyon National Parks (California). More limited assessments focusing on vegetation and air were conducted in 12 secondary parks (fig. 1).