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Air Pollution Impacts

Theodore Roosevelt National Park

Natural and scenic resources in Theodore Roosevelt National Park (NP) are susceptible to the harmful effects of air pollution. Fine particles, nitrogen, ozone, and mercury impact scenic resources such as visibility, and natural resources such as surface waters and vegetation. Click on the tabs below to learn more about air pollutants and their impacts on natural and scenic resources at Theodore Roosevelt NP.

  • Visibility
  • Nitrogen & Sulfur
  • Ozone
  • Toxics & Mercury
Images of good and poor visibility at Theodore Roosevelt National Park, North Dakota
Air pollutants can affect visibility at Theodore Roosevelt NP, North Dakota (clear to hazy from top to bottom).

Many visitors come to Theodore Roosevelt NP to enjoy views of the rugged badlands terrain, wildlife, and other idyllic landscape scenes that charmed Theodore Roosevelt in the 1880s. Unfortunately, nowadays, such vistas are sometimes obscured by haze caused by fine particles in the air. Many of the same pollutants that ultimately fall out as nitrogen and sulfur deposition contribute to this haze and visibility impairment. Organic compounds, soot, and dust reduce visibility as well.

Visibility effects at Theodore Roosevelt NP include:

  • Reduced visibility on some days due to human-caused haze and fine particles of air pollution;
  • Reduction of the average natural visual range from about 140 miles (without the effects of pollution) to about 65 miles because of pollution at the park;
  • Reduction of the visual range to below 40 miles on high pollution days.

(Source: IMPROVE 2010)

Explore scenic vistas through a live webcam at Theodore Roosevelt National Park!

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Little Missouri River at Theodore Roosevelt NP in North Dakota
Surface waters and soils at Theodore Roosevelt NP in North Dakota are considered well-buffered against the acidification effects of nitrogen and sulfur deposition.

Nitrogen and sulfur compounds deposited from air pollution can harm vegetation, soils, and surface waters. Large power plants in Montana and North Dakota, nearby oil and gas well fields, and agriculture are significant sources of airborne nitrogen and sulfur to the park. While soils and surface waters are susceptible to acidification from nitrogen and sulfur deposition, the high buffering capacity of soils in and around Theodore Roosevelt NP and consequent high concentrations of base cations and acid neutralizing capacity in surface waters indicate these ecosystems are not likely to be acidified by atmospheric deposition (Peterson et al. 1998 [pdf, 3.0 MB]). In addition to acidification effects, however, nutrient effects from nitrogen deposition can cause changes to soil nutrient cycling and the species composition of plant communities in some ecosystems. This unwanted fertilization encourages the growth of weedy, invasive plants that out-compete native species and as a result affect biodiversity (Fenn et al. 2003). Current rates of nitrogen deposition are relatively low compared to levels found to affect prairie grass ecosystems (Pardo et al., In Press).

Effects of sulfur and nitrogen deposition at Theodore Roosevelt NP include:

  • Elevated sulfur levels in lichens as compared to soil, suggesting that the atmosphere is a contributing source (Bennett and Wetmore 2001);
  • Comparatively high concentrations of ammonium in wet deposition, often
    an indicator of nearby agricultural sources (NPS 2010 [pdf, 2.8 MB]).

Get Nitrogen & Sulfur Data »


Photo of Saskatoon serviceberry (Amelanchier alnifolia) at Theodore Roosevelt NP in North Dakota.
Saskatoon serviceberry (Amelanchier alnifolia), an ozone-sensitive plant species at Theodore Roosevelt NP in North Dakota.

Naturally-occurring ozone in the upper atmosphere absorbs the sun’s harmful ultraviolet rays and helps to protect all life on earth. However, in the lower atmosphere, ozone is an air pollutant, forming when nitrogen oxides from vehicles, power plants, and other sources combine with volatile organic compounds from gasoline, solvents, and vegetation in the presence of sunlight. In addition to causing respiratory problems in people, ozone can injure plants. Ozone enters leaves through pores (stomata), where it can kill plant tissues, causing visible injury, or reduce photosynthesis, growth, and reproduction.

Ozone concentrations are relatively low but have been worsening at Theodore Roosevelt NP (NPS 2010 [pdf, 2.8 MB]). There are several ozone-sensitive plants in Theodore Roosevelt NP including Populus tremuloides (quaking aspen), Prunus virginiana (choke cherry), and Amelanchier alnifolia (saskatoon serviceberry), although assessments have not documented ozone injury to any sensitive vegetation in the park (Peterson et al. 1998 [pdf, 3.0 MB]).

Search the list of ozone-sensitive plant species (pdf, 184 KB) found at each national park!

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Photo of lichen on a tree at at Theodore Roosevelt NP in North Dakota.
Mercury levels are elevated in lichens at Theodore Roosevelt NP, North Dakota.

Toxic air pollutants include pesticides, industrial by-products, heavy metals like mercury, and flame retardants for fabrics. Lichens, a group of non-vascular plants that accumulate such contaminants and are sensitive to airborne pollutants, can be used as indicators of urban pollution and point-source emissions like oil and gas wells that emit these pollutants.

Mercury levels are elevated in lichens at Theodore Roosevelt NP as compared to levels in soil at the park, suggesting that the atmosphere is a contributing source. Coal-burning power plants are the major sources of mercury to the atmosphere. The heavy metal cadmium and other elements have also been detected in lichens, indicators of the anthropogenic influence (Bennett and Wetmore 2001; Gough et al. 1985).

Once such toxic contaminants enter the food chain, effects in wildlife and humans can include reproductive problems, impaired growth and development, behavioral abnormalities, reduced immune response, chronic illness, cancer, and death.


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Studies and monitoring help the NPS understand the environmental impacts of air pollution. Access air quality data and see what is happening with Studies and Monitoring at Theodore Roosevelt NP.

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Last Updated: December 30, 2016