Recording contaminants in snow data at Mount Rainier National Park. USGS photo.

The National Park Service recently released an important study on the impact of airborne contaminants on parks. The Western Airborne Contaminants Assessment Project (WACAP), a six-year, multi-agency study funded primarily by the National Park Service to evaluate the potential threats to park ecosystems and likely sources of these contaminants, found evidence of numerous airborne contaminants, including heavy metals and both current-use and historic-use pesticides, in 20 western U.S. and Alaska national parks from the Arctic to the Mexican border. While concentrations of most of these contaminants were below levels of concern, others appear to be accumulating in sensitive resources such as fish.

WACAP was undertaken in an effort to determine the risk from airborne contaminants to ecosystems and food webs in eight core parks – Denali, Gates of the Arctic, Glacier, Mount Rainier, Noatak, Olympic, Rocky Mountain, and Sequoia. More limited assessment was conducted in twelve secondary parks – Bandelier, Big Bend, Crater Lake, Glacier Bay, Grand Teton, Great Sand Dunes, Katmai, Lassen Volcanic, North Cascades, Stikine-LeConte Wilderness, Wrangell-St. Elias, and Yosemite.

Results indicate that out of over 100 organic contaminants tested, 70 were found at detectable levels in snow, water, lichen, conifer needles, lake sediment, and/or fish. For some contaminants, high concentrations in fish have exceeded fish-eating wildlife and/or human health consumption thresholds. While the extent of the effects on wildlife populations depending upon fish for survival is unknown, the risk to people is considered low and varies given location and frequency of fish consumption. Most people are not likely to eat enough of the contaminated fish to be at risk.

Evidence suggests that the contaminants found in this study are carried in air masses from sources as far away as Europe and Asia, and as near as the local county. According to Dr. Dixon Landers of the Environmental Protection Agency and the project’s science lead, the presence of contaminants in snow is well-correlated with the proximity of each park to agricultural areas, pointing to these areas as probable major sources of these contaminants.  In Alaska parks, with little nearby agriculture in the region, there are very low concentrations of most current-use compounds.  However, concentrations of historic-use chemicals in Alaska systems are similar to those in the other parks sampled, suggesting greater influence from global atmospheric transport.

Results from this project add considerably to the state of the science concerning contaminant transport and subsequent biological and ecological effects in remote ecosystems in the western U.S. 

“These well-documented and carefully analyzed data will provide a basis for evaluating future changes in the status of these ecosystems,” said Landers.

Among the key findings from the eight core parks are the following:

• measurable amounts of both current use and historic (banned in the U.S.) contaminants were found in snow, water, vegetation, fish and lake sediment;
• parks nearest agricultural areas (Sequoia, Rocky Mountain, Glacier) contained higher levels of both currently used pesticides and pesticides banned some decades ago; historical records of contaminants in lake sediments showed that the ban in the U.S. (in the 70s - 90s) of several key contaminants (e.g., DDTs, dieldrin, chlordanes) has served to reduce deposition of these compounds to lake sediments in some parks further away from agricultural sources, but they are continuing to accumulate in lake sediments of many parks close to agricultural sources;
• contaminants generally increased with elevation, so high elevation areas in parks may be at extra risk for contamination;
• contaminant concentrations of mercury in fish in many parks exceeded risk thresholds for health impacts to fish-eating birds and mammals, while concentrations of DDT in some fish at Sequoia and Glacier and chlordanes in one fish at Glacier exceeded risk thresholds for health impacts to fish-eating birds;
• concentrations of mercury, dieldrin, and/or DDT found in fish from all eight parks exceeded EPA human health thresholds;
• some "intersex" fish (male and female reproductive structures in the same fish) were found in Rocky Mountain and Glacier; and
• some "new" contaminants like PBDEs (flame retardants commonly applied to furniture fabric) show increases in deposition to park ecosystems.

The project, conducted from 2002 to 2007, was coordinated by NPS Air Resources Division staff members in Denver. Other participating institutions included the U.S. Environmental Protection Agency, the U.S. Geological Survey, the U.S. Forest Service, Oregon State University and the University of Washington. National park resource managers worked with scientists from the collaborating agencies to plan and conduct the WACAP study.

For access to the WACAP report and fact sheet, and other related documents and publications, click on the link below.

More Information...

Contact Information
Name: Colleen Flanagan, Air Resources Division