Air quality related values (AQRVs) for Sonoran Desert Network (SODN) parks: Effects from ozone; visibility reducing particles; and atmospheric deposition of acids, nutrients and toxics (revised, 2019)

Sullivan, Timothy

Note that this Sonoran Desert network specific report was originally published in 2016. The 2019 update reflects an error correction to estimated park rankings for nutrient nitrogen pollutant exposure and ecosystem sensitivity to nutrient nitrogen enrichment in the third paragraph on page 16 and in Table 3 on page 17. This report describes the Air Quality Related Values (AQRVs) of the parks in the Sonoran Desert Network (SODN). AQRVs are those resources sensitive to air quality and include streams, lakes, soils, vegetation, fish and wildlife, and visibility. The 11 SODN national park units that are included in the NPS Inventory and Monitoring (I&M) Program and discussed in this report are Casa Grande Ruins National Monument (CAGR), Chiricahua National Monument (CHIR), Coronado National Memorial (CORO), Fort Bowie National Historic Site (FOBO), Gila Cliff Dwellings National Monument (GICL), Montezuma Castle National Monument (MOCA), Organ Pipe Cactus National Monument (ORPI), Saguaro National Park (SAGU), Tonto National Monument (TONT), Tumacácori National Historic Park (TUMA), and Tuzigoot National Monument (TUZI). CHIR and SAGU are Class I air quality areas; the rest of the parks are Class II areas. Risk assessments are reported here for acidification, eutrophication and ozone (O3) for all of the SODN parks. However, because most of the air quality and AQRV data have been collected in the two Class I areas, those parks are the main focus of this report. This report also describes air pollutant emissions and air quality within the SODN region 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” (Sullivan 2016). The SODN generally receives relatively low levels of both S and N atmospheric deposition. Nevertheless, the Phoenix area is an N deposition hotspot that is not well represented in coarse scale atmospheric deposition modeling using models such as the Community Multiscale Air Quality (CMAQ) model. In the most exposed desert and forested areas downwind of Phoenix, N deposition can be many times higher than is estimated from the CMAQ simulations used to estimate regional N deposition for this assessment (Fenn et al. 2003b; http://www.wrapair2.org/WestJumpAQMS.aspx). Little work has been done on the ecological effects of acidification on arid land ecosystems in the SODN, and it is unlikely that such effects have occurred to any significant degree, except perhaps near large urban areas such as Phoenix and Tucson. Acidification effects have not been demonstrated in acid addition experiments at the Central Arizona-Phoenix Long Term Ecological Research (LTER) site within the SODN region, despite the very high levels of added acid deposition (almost 30 kg N/ha/yr). Similarly, there is no information available regarding the possible effects of acidic deposition on aquatic resources in the SODN. Such effects are unlikely in a desert environment. Nitrogen pollutants can also cause undesirable nutrient enrichment of natural ecosystems, leading to changes in plant species distribution and diversity. Nitrogen deposition to arid and semi-arid lands has a heightened potential to increase plant growth, enhance denitrification, alter plant community composition, and increase fire risk. Such changes could alter key ecosystem processes. The two largest parks in the SODN (SAGU and ORPI) are both desert parks. The predominant vegetation types within these parks that are known to be especially sensitive to nutrient N enrichment are.......

Air quality related values (AQRVs) for Sonoran Desert Network (SODN) parks: Effects from ozone; visibility reducing particles; and atmospheric deposition of acids, nutrients and toxics (revised, 2019)

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