For more information about National Park Service air resources, please visit http://www.nature.nps.gov/air/.


Studies on Toxic Contaminants

Including Mercury

Photograph of NPS staff and volunteers netting fish from the shore of Lake McDonald, Glacier NP, MT
Fish sampling for the USGS-NPS mercury study at Lake McDonald, Glacier National Park, MT

Toxics, including heavy metals like mercury, accumulate in the tissue of organisms and may alter key ecosystem processes.

"Air toxics" or airborne contaminants (such as persistent organic pollutants—POPs and heavy metals) have the potential to cause ecosystem impairment in national parks, because the compounds are long-lasting, can accumulate in biological tissue of organisms, and may alter key ecosystem processes.

The National Park Service began a coordinated effort in 2002 to understand bioaccumulation of toxics to NPS areas, and developed a strategy for an air toxics monitoring network in the western U.S. and Alaska, the Western Airborne Contaminants Assessment Project (WACAP). The geographic focus on the west was based on concerns over trans-Pacific transport and accumulation of these toxics in Arctic, near-Arctic, and mid-latitude mountain snowpack. In addition, monitoring of air toxics such as dioxin and mercury has been ongoing in a few selected parks in the eastern U.S., including the Great Lakes area, for several years.

The studies described below represent several of the airborne toxics and mercury projects initiated by the National Park Service.

Mercury in Fish from 21 Western and Alaskan National Parks

National parks contained levels of mercury in some fish that exceeded health thresholds for potential impacts to fish, birds, and humans, according to a U.S. Geological Survey (USGS) and National Park Service (NPS) study (pdf, 6.6MB) published in April, 2014. The project report presents findings on mercury concentrations in more than 1,400 freshwater fish from 86 sites across 21 national parks in 10 western U.S. states, from Alaska to Arizona. The large area covered by this study helps to create a more complete understanding of mercury bioaccumulation patterns in fishes of national parks. Results suggest that while risk is low in many locations, there are significant concerns about the impact of mercury on ecological health in others. Neither the USGS nor the National Park Service regulates environmental health guidelines, but the NPS is coordinating with state officials regarding potential fish consumption advisories. The NPS Office of Public Health is also engaged. For more information, access the 4-page fact sheet (screen/letter [pdf, 1.78 MB] or printer/tabloid [pdf, 784 KB]), NPS/USGS joint press release, USGS Top Story, and/or contact Colleen Flanagan (303-969-2806).

Dragonflies, Mercury, and Citizen Scientists in Parks

The citizen scientist study of mercury in dragonfly larvae project engages students, teachers, and park visitors in the collection of dragonfly larvae for mercury analysis. Up to 50 national parks across the U.S. will be participating in the study in 2014 and 2015. Study results from previous years indicate that dragonfly larvae can describe fine-scale differences in mercury risk, with levels highest in the Northeast U.S. The expanded effort will help better describe the variability of mercury in dragonfly larvae. The study continues to enlighten a new generation of citizen scientists about the connection of all living things and the influence humans have upon natural systems, and how environmentally-responsible decisions can protect our parks and the planet.

Pacific Northwest Contaminant Mapper

A new, interactive map is available to access contaminant sampling locations in the Pacific Northwest, and links to associated fact sheets and reports. These studies provide data on the presence of airborne contaminants such as mercury, pesticides, and other toxics in sediment, water, fish, lichen, and other ecosystem components in the region. This information is important for land managers and scientists to assess ecosystem health. It also provides insight about study gaps and can help identify areas for future research.

Western Airborne Contaminants Assessment Project (WACAP):

The Western Airborne Contaminants Assessment Project (WACAP) was initiated by the NPS in 2002. Sampling continued through 2007 and the final report, "The Fate, Transport, and Ecological Impacts of Airborne Contaminants in Western National Parks (USA)", was released in 2008. The objective of the 6 year project was to inventory airborne contaminants in national park ecosystems using a network of sites in parks of the western US to provide spatially extensive, site specific, and temporally resolved information regarding the exposure, accumulation, and impacts of airborne toxic compounds. NPS is concerned about airborne contaminants because they can pose serious health threats to wildlife and humans, as some of these compounds tend to bioaccumulate in the food chain. EPA, USGS, US Forest Service, University of Washington, and Oregon State University worked with the NPS on this assessment. Dr. Dixon Landers, an EPA scientist, led the project. Snow, lake water, sediment, vegetation, fish, and moose meat were sampled in 8 western parks over the life of this project.


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Last Updated: May 07, 2014