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Studies and Monitoring

Denali National Park & Preserve

Denali National Park & Preserve (NP & Pres), Alaska, has its own unique environmental concerns based on its particular ecology. Air quality studies and monitoring at Denali NP & Pres focus on toxics/mercury, nitrogen, sulfur, ozone, fine particles and haze. Click on the tabs below to review air quality studies and key scientific references at Denali NP & Pres, as well as to access information on air quality monitoring in the park.

  • Studies & Projects
  • Monitoring & Data
  • Key References

Ongoing research in Denali NP & Pres, Alaska:

International Transport of Airborne Pollutants to
Denali NP & Pres

Alaska sites such as Denali NP & Pres serve as good sentinels for determining the extent and type of contaminants originating from international or global sources because the sites are remote and local/regional contaminant inputs are minimal. Winds can transport contaminants across the Pacific to Alaska in 5 days or less with dominant wind patterns originating both in Siberia and also in British Columbia. For example, Landers et al. (2008) found that pesticides (e.g., dieldrin, chlordane) banned in the U.S. for several decades are present in snow and plants at Denali NP & Pres and other Alaska sites. This is likely due to atmospheric transport from countries that continue to use these chemicals. Concentrations of some of these banned pesticides in fish in Alaska parks were generally above those found in parks in the lower 48, indicating that these banned chemicals are accumulating in fish over time.

Visibility Impacts

Air quality and visibility in Denali are usually excellent, although small amounts of pollution are measured in the park each year. Haze-causing pollutants in Denali show a strong seasonal pattern, with a peak in the late winter and spring. The peak coincides with intercontinental transport of pollutants primarily from industrial sources, and can be seen throughout interior Alaska. In the summer, it is not uncommon for smoke from naturally-occurring wildland fires to obscure the view. Arctic and subarctic research continues with regard to the presence of transboundary pollutants in the region.

Toxics/Mercury Impacts

The ecological effects of mercury deposition and the deposition of other toxic airborne contaminants including persistent organic pollutants (POPs) in Denali NP & Pres has been assessed in recent years by the Western Airborne Contaminants Assessment Project (WACAP) and the Arctic Monitoring and Assessment Programme (AMAP). Study findings indicate the presence of contaminants at relatively low concentrations in vegetation, lake water, snow, sediments, and air. Concentrations of PCBs, mercury, and dieldrin, however, were higher than expected in some park fish. Measured contaminants in fish did not exceed human health thresholds adopted by the State of Alaska, nor did they exceed human health thresholds established by the EPA for consumers eating fewer than 19 meals of fish per month (Ackerman et al. 2008; Landers et al. 2010; Landers et al. 2008; Schwindt et al. 2008). find data »

Arctic and subarctic ecosystems like Denali NP & Pres are particularly susceptible to accumulating POPs and other toxic airborne contaminants. In warmer climates, POPs are deposited from the atmosphere, but tend to revolatilize back into the air. In colder parts of the world such as Denali NP & Pres, POPs—once deposited—tend to remain in an ecosystem because revolatilization is slower. Over time, this can lead to the accumulation of POPs and other toxic airborne contaminants. is a forum established to facilitate collaboration in the development of an effective framework and monitoring strategy for contaminants in Alaska.

Ground-Level Ozone Impacts

Ozone concentrations have been continuously measured at Denali NP & Pres since 1987. Concentrations are generally very low and unlikely to affect vegetation. find data »

Nitrogen & Sulfur Impacts

Nitrogen and sulfur compounds in deposition have been continuously measured at Denali NP & Pres since 1980. Measured amounts are generally very low and unlikely at current levels to affect soils, streams, lakes, or vegetation at the park. find data »

Air quality monitoring information and data access:

Air Pollutant/Impact

Monitoring Program

Sites and Data Access

Visibility IMPROVE
Toxics WACAP
Nitrogen Wet deposition NADP/NTN
Dry deposition CASTNet

Abbreviations in the above table:

    CASTNet: EPA Clean Air Status and Trends Network
    GPMP: Gaseous Pollutant Monitoring Program
    IMPROVE: Interagency Monitoring of Protected Visual Environments
    NADP: National Atmospheric Deposition Program
    NP & Pres: National Park & Preserve
    NPS: National Park Service
    NTN: National Trends Network
    VIEWS: Visibility Information Exchange Web System
    WACAP: Western Airborne Contaminants Assessment Project

For more information regarding monitoring and data assessments conducted by the National Park Service, link to the NPS Air Quality Monitoring Program or to the NPS Air Quality Monitoring History Database for a history of active and inactive monitoring sites at Denali NP & Pres.

Key air quality related references from Denali NP & Pres, Alaska:

Ackerman, L. K., Schwindt, A. R., Massey Simonich S. L., Koch, D. C., Blett, T. F., Schreck, C. B., Kent, M. L., Landers, D. H. 2008. Atmospherically Deposited PBDEs, Pesticides, PCBs, and PAHs in Western U.S. National Park Fish: Concentrations and Consumption Guidelines. Environmental Science & Technology 42: 2334–2341.

Hageman, K. J., Simonich, S. L., Campbell, D. H., Wilson, G. R., Landers, D. H. 2006. Atmospheric deposition of current-use and historic-use pesticides in snow at national parks in the Western United States. Environmental Science & Technology 40: 3174–3180

[IMPROVE] Interagency Monitoring of Protected Visual Environments. 2010. Improve Summary Data. Available at

Landers, D. H., Simonich, S. M., Jaffe, D., Geiser, L., Campbell, D. H., Schwindt, A., Schreck, C., Kent, M., Hafner, W., Taylor, H. E., Hageman, K., Usenko, S., Ackerman, L., Schrlau, J., Rose, N., Blett, T., Erway, M. M. 2010. The Western Airborne Contaminant Assessment Project (WACAP): An Interdisciplinary Evaluation of the Impacts of Airborne Contaminants in Western U.S. National Parks. Environmental Science and Technology 44: 855–859.

Landers, D. H., S. L. Simonich, D. A. Jaffe, L. H. Geiser, D. H. Campbell, A. R. Schwindt, C. B. Schreck, M. L. Kent, W. D. Hafner, H. E. Taylor, K. J. Hageman, S. Usenko, L. K. Ackerman, J. E. Schrlau, N. L. Rose, T. F. Blett, and M. M. Erway. 2008. The Fate, Transport, and Ecological Impacts of Airborne Contaminants in Western National Parks (USA). EPA/600/R—07/138. U.S. Environmental Protection Agency, Office of Research and Development, NHEERL, Western Ecology Division, Corvallis, Oregon. Available at

Nelson, P., Walton, J. and Roland, C. 2009. Erioderma pedicellatum (Hue) P. M. Jorg., New to the United States and Western North America, Discovered in Denali National Park and Preserve and Denali State Park, Alaska. Evansia 25: 19–23.

Oltmans S. J., Lefohn, A. S., Harris, J. M., Tarasick, D. W., Thompson, A. M., Wernli, H., Johnson, B. J., Novelli, P. C., Montzka, S. A., Ray, J. D., Patrick, L. C., Sweeney, C., Jefferson, A., Dann, T., Davies, J., Shapiro, M., Holben, B. N. (In Press 2010). Enhanced ozone over western North America from biomass burning in Eurasia during April 2008 as seen in surface and profile observations. Atmospheric Environment.

Schwindt, A. R., Fournie, J. W., Landers, D. H., Schreck, C. B., Kent, M. 2008. Mercury Concentrations in Salmonids from Western U.S. National Parks and Relationships with Age and Macrophage Aggregates. Environmental Science & Technology 42 (4): 1365–1370.

Sullivan, T. J., McDonnell, T. C., McPherson, G. T., Mackey, S. D., Moore, D. 2011a. Evaluation of the sensitivity of inventory and monitoring national parks to nutrient enrichment effects from atmospheric nitrogen deposition: main report. Natural Resource Report NPS/NRPC/ARD/NRR—2011/313. National Park Service, Denver, Colorado. Available at

Sullivan, T. J., McDonnell, T. C., McPherson, G. T., Mackey, S. D., Moore, D. 2011b. Evaluation of the sensitivity of inventory and monitoring national parks to nutrient enrichment effects from atmospheric nitrogen deposition: Central Alaska Network (CAKN). Natural Resource Report NPS/NRPC/ARD/NRR—2011/330. National Park Service, Denver, Colorado. Available at (pdf, 7.4 MB).

Featured Content

Impacts icon

Pollutants including mercury, ozone, sulfur, nitrogen, and fine particles affect resources such as forests, streams, wildlife, and scenic vistas. Find out how on our Denali NP & Pres Air Pollution Impacts web page.

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Last Updated: January 03, 2017