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Petrified Forest National Park Air Quality Information

Overview

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Petrified Forest National Park, Arizona
Petrified Forest National Park (NP), located in northeastern Arizona, Apache County, was first established as a national monument in 1906. The monument was created to protect and preserve the world’s largest concentration of petrified wood, as well as archeological ruins and petroglyphs, and portions of the Painted Desert. In 1962, this unique monument was converted to a national park and today comprises 93,533 acres of land including 50,260 acres of designated wilderness. The semi-arid environment of the park is dominated by grasslands with some conifer woodland communities.

Both local and distant air pollutant sources affect air quality in Petrified Forest NP. Large power plants in Navajo, Coconino, and Apache counties in Arizona and San Juan and McKinley counties in New Mexico are the largest nearby point sources of sulfur dioxide and nitrogen oxides. Pollutants also travel great distances to the park from industrial and urban areas of southern California, southern Arizona, and northern Mexico.

Air quality related values (AQRVs) of Petrified Forest NP are those resources that are potentially sensitive to air pollution, and include vegetation, wildlife, soils, and visibility. The park has no surface waters. At present, visibility has been identified as the most sensitive AQRV in the park. Small air pollution particles cause haze and obscure visibility in the park. The ability of visitors to see the subtle pastel colors of the Painted Desert may be particularly sensitive to changes in haziness.

As part of the Interagency Monitoring of Protected Visual Environments (IMPROVE) network, visual air quality in Petrified Forest NP has been monitored using an aerosol sampler (1988 through the present), transmissometer (1987 through the present), and 35mm camera (1987 to 1994). The U.S. Environmental Protection Agency’s new Regional Haze regulations require States to establish goals for each Class I air quality area to improve visibility on the haziest days and ensure no degradation occurs on the clearest days. An analysis of 1990-1999 data indicates that visibility in Petrified Forest NP has neither improved nor degraded significantly during that time.

There is little information available on the sensitivity of soils or vegetation in Petrified Forest NP to atmospheric deposition of sulfur and nitrogen. Soils are likely to be well-buffered from acidification effects; however, soils and vegetation may be sensitive to deposition of nitrogen compounds. In some parts of the country, nitrogen deposition has caused changes in soil nutrient cycling and vegetation species composition.

Wet deposition of sulfur and nitrogen compounds has been monitored in Petrified Forest NP since 2002 as part of the National Atmospheric Deposition Program/National Trends Network (NADP/NTN). Insufficient data are available to detect trends; however, at many sites on the Colorado Plateau, sulfur in wet deposition is decreasing and nitrogen is increasing. The site ID is AZ97. Dry deposition has been monitored at Petrified Forest NP since 2002 as part of the Clean Air Status and Trends Networks (CASTNet).

Several plant species that occur in Petrified Forest are known to be sensitive to atmospheric ozone (e.g., Rhus trilobata) although the specific genotypes found in the park have not been tested under controlled conditions for sensitivity. Plants in the park have not been evaluated systematically for ozone injury.

Ozone concentrations have been monitored in Petrified Forest NP from 1987-1991 and from late 2002 to the present. An analysis of the data indicates that, although average ozone concentrations were too low to cause any impact on sensitive species, the peak concentrations were sufficient to affect sensitive species. Cumulative exposures were near the lower threshold for effects on sensitive species. During the period 1987-1991, the park consistently had higher peak concentrations than any other park or monument on the Colorado Plateau. The data record from late 2002 to the present is not sufficient for trend analysis. However, an analysis of 1990-1999 ozone data from other parks on the Colorado Plateau (e.g., Mesa Verde, Canyonlands, and Grand Canyon ) shows a significant increasing trend in ozone concentrations. Recent estimates for Petrified Forest NP indicate that current ozone concentrations may be sufficient to induce injury on sensitive species. Sulfur dioxide concentrations were monitored from 1988 to 1993 and the measured values were far below any threshold of suggested sensitivity for any plants.

Additional information on in-park emissions at Petrified Forest NP is available in 2000 Air Emission Inventory- Petrified Forest National Park (September 2001). Disclaimer: Links within the above document were valid as of the date published.

Additional information relative to air quality and air quality related values at Petrified Forest NP is available in D. Binkley et al. 1997. Status of Air Quality and Related Values in Class I National Parks and Monuments of the Colorado Plateau. National Park Service. Denver, CO.

updated on 11/01/2006  I   http://nature.nps.gov/air/Permits/ARIS/pefo/index.cfm   I  Email: Webmaster