Air quality related values (AQRVs) for Appalachian Highlands Network (APHN) parks: Effects from ozone; visibility reducing particles; and atmospheric deposition of acids, nutrients and toxics

Sullivan, Timothy

This report describes the Air Quality Related Values (AQRVs) of the Appalachian Highlands Network (APHN). AQRVs are those resources sensitive to air quality and include streams, lakes, soils, vegetation, fish and wildlife, and visibility. The APHN parks that are included in the NPS Inventory and Monitoring (I&M) Program, and discussed in this report, are Great Smoky Mountains National Park (GRSM), Big South Fork National River and Recreation Area (BISO), Blue Ridge Parkway (BLRI), and Obed Wild and Scenic River (OBRI). GRSM is designated as Class I, giving it a heightened level of protection against harm caused by poor air quality under the Clean Air Act (CAA). Sullivan et al. (2011a, 2011b) and Kohut (2007a) conducted risk assessments for acidification, eutrophication, and ozone (O3) for all of the NCCN parks; their results are described in this report. This report also describes air pollutant emissions and air quality, and their effects on AQRVs. The primary pollutants likely to affect AQRVs include nitrogen (N) and sulfur (S) compounds (nitrate [NO3-], ammonium [NH4+], and sulfate [SO42-]); ground-level O3; haze-causing particles; and airborne toxics. Background for this section can be found in “Air Quality Related Values (AQRVs) in National Parks. Effects from Ozone; Visibility Reducing Particles; and Atmospheric Deposition of Acids, Nutrients and Toxics – Main Report” (Sullivan 2016). Air pollution is an important concern in the APHN, and effects have been well-studied, especially within GRSM. Upwind emissions and deposition of both S and N are high in and around the APHN. In particular, S and N deposition are high at the upper elevations (especially above about 1,500 m) in GRSM, where cloud deposition contributes substantial amounts of S and N to acid-sensitive spruce-fir forests. Wet deposition of mercury (Hg) is also fairly high. The most important air pollution concerns in the APHN include visibility, O3 exposure , and acidification of soil and surface water. Pollution-caused haze levels are very high in GRSM. Ozone has harmed sensitive plant species. Many streams have acidified. There are known biological effects of acidification on acid-sensitive vegetation and aquatic biota in higher elevation, low-order stream watersheds. Although acidic deposition has declined substantially over the past two decades in this network, effects of S deposition may intensify in the future even under further reduced S loading. This is because soils in GRSM have adsorbed significant amounts of S over time, limiting acidification under relatively high levels of S deposition. As this adsorption capacity is exhausted, however, continued S input, albeit at lower levels, will trigger delayed acidification responses in soils and drainage waters. Ozone exposures and risk to sensitive vegetation reported by Kohut (2007a) were moderate to high within the APHN, depending on the park unit and choice of exposure index on which to base the assessment. Based on both O3 cumulative exposure and Kohut’s (2007a) risk ranking index, concern for O3 effects on vegetation is high in all of the I&M parks that occur in the APHN, except BLRI. GRSM contains some of the largest tracts of old-growth forest in the eastern United States. Old-growth spruce-fir forests predominate at elevations above 1,500 m in the park. Mixed hardwood forests cover the lower slopes. Although atmospheric deposition of both S and N has been high in the park, deposited N has the largest influence on stream chemistry because watershed retention of atmospherically deposited S has been high (Flum and Nodvin 1995). Streams in GRSM draining old-growth coniferous forests commonly have had NO3- concentrations above 50 µeq/L, which has been higher than at most lower elevation sites. File size: 2.9 MB

Air quality related values (AQRVs) for Appalachian Highlands Network (APHN) parks: Effects from ozone; visibility reducing particles; and atmospheric deposition of acids, nutrients and toxics

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