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Studies and Monitoring

Big Bend National Park

Big Bend National Park (NP), Texas, has its own unique environmental concerns based on its particular ecology. Air quality studies and monitoring programs at Big Bend NP focus on the deposition of nitrogen and sulfur compounds, toxic contaminants, ozone, and visibility assessments. Click on the tabs below to review air quality studies and key scientific references at Big Bend NP, as well as to access information on air quality monitoring in the park.

  • Studies & Projects
  • Monitoring & Data
  • Key References

Ongoing research in Big Bend NP, Texas:

Visibility Impacts

Big Bend NP visitors often experience reduced visibility of the park’s scenic views. The NPS and the Environmental Protection Agency (EPA) conducted the Big Bend Regional Aerosol and Visibility Observational (BRAVO) study to explore this obstructive haze (NPS 2004; BRAVO Fact sheet [pdf, 157 KB]). The primary objective of this intensive study was to determine the chemical composition of haze, emission sources, and major local and regional contributions. The BRAVO study found that sulfate particles are the single largest contributor to haze in the park. Sulfate emission sources frequently associated with the park’s haze include coal-fired power plants, metal smelters, refineries, other industrial sources, and volcanoes. BRAVO results further indicated that emission sources from eastern Texas and eastern states in the U.S. on average contribute 55 percent to the haziest days at Big Bend NP (Pitchford et al. 2004). Current federal regulations that reduce sulfur dioxide emissions should make progress toward improving visibility at the park. While sources in Mexico were also shown to contribute to visibility impairment at Big Bend NP, the U.S. government has no jurisdiction there. Partnerships between agencies in Mexico and the U.S., such as Border 2012, have been established to address the transport of pollution.

Nitrogen & Sulfur Impacts

Previous work has documented the potential effects of nitrogen and sulfur deposition on arid landscapes in the park. Compounded with climate change, nitrogen deposition has the ability to increase fuel loading and affect the biodiversity of soil microbes (Zak 2006). Elevated levels of nitrogen have been found in the terrestrial ecosystem. Future work in the park will quantify nitrogen and sulfur deposition in the park and further assess the microbial responses to such atmospheric pollutants.

Airborne Toxic Contaminants Impacts

Air currents transport contaminants (e.g., pesticides, industrial pollutants, and heavy metals) from their sources and deposit them through rain, snow, and dry deposition at Big Bend NP. Elevated levels of airborne contaminants have been documented in air and vegetation samples from the park (Landers et al. 2010; Landers et al. 2008; Cleverly et al. 2000 [pdf, 110 KB]). Additionally, DDE and mercury were found in birds (e.g., peregrine falcons), at levels possibly associated with impaired reproduction (Mora et al. 2002). Big Bend NP is one of 33 sampling sites throughout the U.S. in EPA’s National Dioxin Air Monitoring Network (NDAMN), a project established to determine atmospheric levels of dioxin-like compounds (e.g., PCBs) at rural and non-impacted locations of the U.S.

Air quality monitoring information and data access:

Air Pollutant/Impact

Monitoring Program

Sites and Data Access

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

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
    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 Big Bend NP.

Cleverly, D. H., D. Winters, J. Ferrario, J. Schaum, G. Schweer, J. Buchert, C. Greene, A. Dupuy, C. Byrne. The National Dioxin Air Monitoring Network (NDAMN): Results of the First Year of Atmospheric Measurements of CDDs, CDFs, and Dioxin-Like PCBs in Rural and Agricultural Areas of the United States: June 1998–June 1999. Presented at Dioxin ’00, 20th International Symposium on Halogenated Environmental Organic Pollutants & POPS, held Aug 13–17 at Monterey, CA. Short paper in, Organohalogen Compounds 45: 248–251. Available at (pdf, 110 KB).

[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

Mora, M., Skiles, R., McKinney, B., Paredes, M., Buckler, D., Papoulias, D., Klein, D. 2002. Environmental contaminants in prey and tissues of the peregrine falcon in the Big Bend Region, Texas, USA. Environ Pollut. 116 (1): 169–176.

[NPS] National Park Service. 2004. Understanding Haze in Big Bend National Park—Big Bend Regional Aerosol and Visibility Observational (BRAVO) Study. Fact sheet. Available at (pdf, 157 KB).

Pitchford, M. L., Tombach, I., Barna, M., Gebhart, K. A., Green, M. C., Knipping, E., Kumar, N., Malm, W. C., Pun, B., Schichtel, B. A., Seigneur, C. 2004. Big Bend Regional Aerosol and Visibility Observational Study Final Report. Available at

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: Chihuahuan Desert Network (CHDN). Natural Resource Report NPS/NRPC/ARD/NRR—2011/330. National Park Service, Denver, Colorado. Available at (pdf, 7.4 MB).

Zak, J. 2006. Impacts of Atmospheric Nitrogen Deposition and Climate Change on Desert Ecosystems. Big Bend National Park. NPS Final Report. 15 pp.

Featured Content

Impacts icon

Pollutants including fine particles, nitrogen, sulfur, ozone, and mercury affect resources such as streams, soils, and scenic vistas. Find out how on our Big Bend NP Air Pollution Impacts web page.

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Last Updated: January 03, 2017