- Air quality at North Cascades National Park
- Related references
Air quality at North Cascades National Park
Most visitors expect clean air and clear views in parks. North Cascades National Park (NP), Washington, is in close proximity to the fast-growing Seattle and Vancouver metropolitan areaslies. The park is downwind of air pollution from the Puget Sound lowlands and Fraser River Valley of British Columbia and sometimes is affected by air masses originating in Asia. Air pollutants blown into the park can harm natural and scenic resources such as soils, surface waters, plants, wildlife, and visibility. The National Park Service works to address air pollution effects at North Cascades NP, and in parks across the U.S., through science, policy and planning, and by doing our part.
Nitrogen and sulfur
Nitrogen and sulfur compounds deposited from the air may have harmful effects, including acidification, on soils, lakes, ponds, and streams. High elevation lakes and streams in the park are sensitive to atmospheric deposition of sulfur and nitrogen pollutants due to a limited ability to neutralize acid deposition (Sullivan et al. 2011c; Sullivan et al. 2011d). North Cascades NP also has numerous plants that are sensitive to acidification (search for acid-sensitive plant species). The park’s high elevation ecosystems are also sensitive nitrogen deposition due to limited ability to absorb excess nitrogen. Excess nitrogen can lead to nutrient enrichment, a process that changes nutrient cycling and alters plant communities.
Healthy ecosystems can naturally buffer a certain amount of pollution, but as nitrogen and sulfur accumulate, a threshold is passed where the ecosystem is harmed. “Critical load” is a term used to describe the amount of pollution above which harmful changes in sensitive ecosystems occur (Porter 2005). Nitrogen deposition in the park is approaching levels known to affect alpine lakes and plant communities. North Cascades NP receives elevated nitrogen deposition compared to other sites in the region, resulting in increased surface water nitrate concentration (Clow and Campbell 2008). The largest regional sources of nitrogen and sulfur include agriculture, refineries, aluminum smelters, and automobiles (Basabe et al. 1989a).
Nitrogen and sulfur effects:
- Spring snowmelt, late summer storms, or rain-on-snow can release acids accumulated in snow that are harmful to aquatic life and amphibians (Clow and Campbell 2008).
- Increased nitrate concentrations in alpine lakes as elevation increases, suggest that atmospheric deposition contributes to the increasing levels of nitrogen in high elevation lakes (Larson et al. 1999).
- In the Columbia River Gorge and the Willamette Valley, sensitive lichen species important to wildlife have declined and been replaced by pollution-tolerant species (Geiser and Neitlich 2007; Geiser et al. 2010).
- Nitrogen deposition exceeds the critical load for one or more park ecosystems (NPS ARD 2018).
Visit the NPS air quality conditions and trends website for park-specific nitrogen and sulfur deposition information. North Cascades NP has been monitoring nitrogen and sulfur since 1984. Explore air monitoring »
Mercury and toxics
Airborne mercury, and other toxic air contaminants, when deposited are known to harm birds, salamanders, fish and other wildlife, and cause human health concerns. These substances enter the food chain and accumulate in the tissue of organisms causing reduced reproductive success, impaired growth and development, and decreased survival.
Air currents transport toxics from their sources and deposit them in rain, snow, and dryfall at North Cascades NP. Human activities greatly increase the amount of mercury in the environment through processes such as burning coal for electricity and burning waste. Other toxics of concern include pesticides, industrial by-products, and emerging chemicals. Some of these toxics are also known or suspected to cause cancer or have serious chronic health effects in humans and wildlife.
Mercury and toxics effects:
- Contaminants including mercury, current-use pesticides, historic-use pesticides, and industrial by-products have been found in air, vegetation, and fish in the park (Moran et al. 2007; Landers et al. 2010; Landers et al. 2008);
- Fish from lakes with elevated mercury and toxics contaminant levels in North Cascades NP display changes in metabolic, endocrine, and immune response-related genes, compared to fish from uncontaminated lakes (Moran et al. 2007);
- Elevated concentrations of current-use pesticides found in park vegetation (Landers et al. 2010; Landers et al. 2008);
- Elevated levels of current-use pesticides and other toxics in air and vegetation samples compared to other national parks (Landers et al. 2010; Landers et al. 2008).
- Dragonfly larvae collected by citizen scientists from some sites at the park have elevated mercury levels. See project results.
Explore an interactive map of contaminant sampling in the Pacific Northwest.
At ground level, ozone is harmful to human health and the environment. Ground-level ozone does not come directly from smokestacks or vehicles, but instead is formed when other pollutants, mainly nitrogen oxides and volatile organic compounds, react in the presence of sunlight.
Over the course of a growing season, ozone can damage plant tissues making it harder for plants to produce and store food. It also weakens plants making them less resistant to disease and insect infestations. Ozone concentrations in the region are generally low, and ozone injury to plants in the park has not been evaluated. Still, some plants are more sensitive to ozone than others. Several species in the park, including Pinus ponderosa (ponderosa pine) and Populus tremuloides (quaking aspen), are known to be sensitive to ozone. Search for more ozone-sensitive plant species found at North Cascades NP.
Visit the NPS air quality conditions and trends website for park-specific ozone information.
Many visitors come to North Cascades NP to enjoy views of the “American Alps,” including jagged spires, sheer cliffs, and glaciers. Unfortunately, these vistas are sometimes obscured by haze. Visibility reducing haze is caused by tiny particles in the air, and these particles can also affect human health. Many of the same pollutants that ultimately fall out as nitrogen and sulfur deposition contribute to this haze. Organic compounds, soot, dust, and wood smoke reduce visibility as well. Significant improvements in park visibility have been documented since the 2000’s. Overall, visibility in the park still needs improvement to reach the Clean Air Act goal of no human caused impairment.
- Reduction of the average natural visual range from about 155 miles (without the effects of pollution) to about 140 miles because of pollution at the park;
- Reduction of the visual range from about 110 miles to below 75 miles on high pollution days.
- A 1990 study called PREVENT (Pacific Northwest Regional Visibility Experiment Using Natural Tracers) found that sulfur (largely from nearby power plants and urban sources) is the largest contributor to reduced visibility at North Cascades NP. Nitrates also contribute to visibility reduction at the park and are mostly from emissions from pulp and paper mills, fires, power plants, and transportation (Malm et al. 1994).
Visit the NPS air quality conditions and trends website for park-specific visibility information. North Cascades NP has been monitoring visibility since 1997. View a live air quality webcam, and explore air monitoring »
Barna, M., Lamb, B., O’Neill, S., Westberg, H., Figueroa-Kaminsky, C. Otterson, S., Bowman, C., and DeMay, J. 2000. Modeling Ozone Formation and Transport in the Cascadia Region of the Pacific Northwest. Journal of Applied Meteorology 39: 349–366.
Basabe, F. A., Edmonds, R. L., Chang, W. L., and Larson, T. V. 1989a. Fog and cloudwater chemistry in Western Washington. In: Olson, R. K. and Lefohn, A. S. (eds.) Symposium on the effects of air pollution on western forests. June 1989. Anaheim, CA. Air and Waste Management Association. pp. 33–49.
Brace, S. and Peterson, D. L. 1998. Spatial Patterns of Tropospheric Ozone in the Mount Rainier Region of the Cascade Mountains, U.S.A. Atmospheric Environment 32(21): 3629–3637.
Clow, D. W. and Campbell, D. H. 2008. Atmospheric deposition and surface-water chemistry in Mount Rainier and North Cascades National Parks, U.S.A., water years 2000 and 2005–2006: U.S. Geological Survey Scientific Investigations Report 2008—5152, 37 pp. Available at https://irma.nps.gov/DataStore/Reference/Profile/664042.
Eilers, J. M., Rose, C. L., Sullivan, T. J. 1994. Status of Air Quality and Effects of Atmospheric Pollutants on Ecosystems in the Pacific Northwest Region of the National Park Service. NPS Final Report. 255 pp. Available at https://irma.nps.gov/DataStore/Reference/Profile/118233.
Fenn, M., Geiser, L., Peterson, J., Waddell, E., and Porter, E. 2003. Why Federal Land Managers in the Northwest are Concerned about Nitrogen Emissions. National Park Service. 18 pp. Available at https://irma.nps.gov/DataStore/Reference/Profile/606872.
Geiser, L. H., Jovan, S. E., Glavich, D. A., Porter, M. K. 2010. Lichen-based critical loads for atmospheric nitrogen deposition in Western Oregon and Washington Forests, USA. Environmental Pollution 158: 2412–2421.
Geiser, L. and Neitlich, P. 2007. Air pollution and climate gradients in western Oregon and Washington indicated by epiphytic macrolichens. Environmental Pollution 145: 203–218.
Jaffe, D., McKendry, I., Anderson, T., Price, H. 2003. Six ‘new’ episodes of trans-Pacific transport of air pollutants. Atmos. Envir. 37: 391–404.
Kohut R.J. 2007. Ozone Risk Assessment for Vital Signs Monitoring Networks, Appalachian National Scenic Trail, and Natchez Trace National Scenic Trail. NPS/NRPC/ARD/NRTR—2007/001. National Park Service. Fort Collins, Colorado. Available at https://www.nps.gov/articles/ozone-risk-assessment.htm
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 https://irma.nps.gov/DataStore/Reference/Profile/660829.
Larson, G. L., Lomnicky, G., Hoffman, R., Liss, W. J., and Deimling, E. 1999. Integrating physical and chemical characteristics of lakes into the glacially influenced landscape of the Northern Cascade Mountains, Washington State, U.S.A. Environmental Management 24(2): 219–228.
Malm, W. C., Gebhart, K. A., Molenar, J., Eldred, R., Harrison, H. 1994. Pacific Northwest Regional Visibility Experiment Using Natural Tracers—PREVENT. National Park Service Final Report. Available at http://vista.cira.colostate.edu/Improve/final-report-prevent/.
Moran P. W., Aluru, N., Black, R. W., Vijayan, M. M. 2007. Tissue contaminants and associated transcriptional response in trout liver from high elevation lakes of Washington. Environ Sci Technol. 41(18): 6591–6597
Porter, E., Blett, T., Potter, D.U., Huber, C. 2005. Protecting resources on federal lands: Implications of critical loads for atmospheric deposition of nitrogen and sulfur. BioScience 55(7): 603–612. https://doi.org/10.1641/0006-3568(2005)055[0603:PROFLI]2.0.CO;2
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 https://www.nps.gov/articles/nitrogen-risk-assessment.htm
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: North Coast and Cascades Network (NCCN). Natural Resource Report NPS/NRPC/ARD/NRR—2011/330. National Park Service, Denver, Colorado. Available at https://irma.nps.gov/DataStore/Reference/Profile/2168709.
Sullivan, T. J., McPherson, G. T., McDonnell, T. C., Mackey, S. D., Moore, D. 2011c. Evaluation of the sensitivity of inventory and monitoring national parks to acidification effects from atmospheric sulfur and nitrogen deposition: main report. Natural Resource Report NPS/NRPC/ARD/NRR—2011/349. National Park Service, Denver, Colorado. Available at https://www.nps.gov/articles/acidification-risk-assessment.htm.
Sullivan, T. J., McPherson, G. T., McDonnell, T. C., Mackey, S. D., Moore, D. 2011d. Evaluation of the sensitivity of inventory and monitoring national parks to acidification effects from atmospheric sulfur and nitrogen deposition: North Coast and Cascades Network (NCCN). Natural Resource Report NPS/NRPC/ARD/NRR—2011/349. National Park Service, Denver, Colorado. Available at https://irma.nps.gov/DataStore/Reference/Profile/2170593.
Sullivan T.J. 2016. Air quality related values (AQRVs) in national parks: Effects from ozone; visibility reducing particles; and atmospheric deposition of acids, nutrients and toxics. Natural Resource Report. NPS/NRSS/ARD/NRR—2016/1196. National Park Service. Fort Collins, Colorado. Available at https://www.nps.gov/articles/aqrv-assessment.htm.
Last updated: September 27, 2018