Ozone Exposure and Potential for Vegetation Injury within the Atlanta, Georgia Metropolitan Area

Article excerpt

Ozone-induced vegetation injury may be prevalent within metropolitan areas in the southeastern United States. The purpose of this study is to explore the relationship between ozone exposure and potential foliar injury within the Atlanta, Georgia metropolitan statistical area (MSA). The main methods involve calculating seasonal ozone exposure at 11 monitoring stations in the Atlanta MSA for 2000-2005 and measuring ozone-induced visible foliar injury in the eastern portion of the MSA in August 2004. Ozone exposure within the Atlanta MSA probably was high enough to injure only highly sensitive species, and the 2004 survey did reveal foliar injury to highly sensitive species.

KEY WORDS: ozone, foliar injury, Atlanta

INTRODUCTION

High concentrations of ground-level ozone exist throughout the interior portion of the southeastern United States. Ground-level ozone is formed by photochemical reactions involving volatile organic compounds (VOCs) and nitrogen oxides ([NO.sub.x]) (Haagen-Smit 1952; Crutzen 1979). The interior Southeast has high ozone concentrations during the summer because of (1) the predominance of high-pressure systems and associated atmospheric conditions (i.e. high solar radiation, high temperatures, and poor ventilation) (Vukovich et al. 1977; Vukovich 1994); (2) abundant biogenic VOCs (BVOCs) (Chameides et al. 1988; Geron et al. 1994; Geron et al. 1995); and (3) large emissions of N[O.sub.x] from motor vehicles and from coal-fired power plants throughout the region (US EPA 2006a; Ryerson et al. 2001). Ozone nonattainment areas (i.e. areas exceeding the federal ozone standard) in the southeastern United States include the following metropolitan statistical areas (MSAs): Atlanta, Birmingham, Charlotte-Gastonia-Rock Hill, Chattanooga, Clarksville-Hopkinsville, Fayetteville, Greensboro-Winston Salem-High Point, Greenville-Spartanburg-Anderson, Hickory-Morganton-Lenoir, Johnson City-Kingsport-Bristol, Knoxville, Macon, Nashville, Raleigh-Durham-Chapel Hill, and Rocky Mount, (US EPA 2006b) (Figure 1).

Many plant species native to the southeastern United States may be sensitive to ozone. At least 20 species in Great Smoky Mountains National Park (GSMNP), part of which is located in the eastern portion of the Knoxville, Tennessee MSA (Figure 1), have been confirmed in Neufeld et al. (1992) as being sensitive to ozone, and those species include American sycamore (Platanus occidentalis L.), black cherry (Prunus serotina Ehrh.), blackeyed Susan (Rudbeckia hirta L.), cutleaf coneflower (Rudbeckia laciniata L.), eastern redbud (Cercis canadensis L.), flowering dogwood (Cornas florida L.), Great Smoky Mountain mannagrass (Glyceria nubigena W.A. Anderson), New York ironweed (Vernonia noveboracensis (L.) Michx.), poke milkweed (Asclepias exalta L.), red maple (Acer rubrum L.), Rugel's Indianplantain (Cacalia rugelia Shuttlw. ex Chapman), sassafras (Sassafras albidum (Nutt.) Nees), smooth blackberry (Rubus canadensis L.), sweetgum (Liquidambar styraciflua L.), Table Mountain pine (Pinus pungens Lamb.), whorled wood aster (Aster acuminatus Michx.), winged sumac (Rhas copallinum L.), yellow buckeye (Aesculas tiara Ait.), yellow crownbeard (Verbesina occidentalis (L.) Walt.), and yellow-poplar (Liriodendron tulipifera L.). The highly sensitive species are American sycamore, black cherry, blackeyed Susan, cutleaf coneflower, poke milkweed, red maple, sassafras, Table Mountain pine, winged sumac, and yellow crownbeard (Neufeld et al. 1992). Loblolly pine (Pinus taeda L.), a prevalent species in the Southeast, also may be sensitive to ozone. Kuehler and Flagler (1999) and Manning et al. (2003) note that seedlings of a half-sib family, S6PT2, are sensitive to ozone.

Despite the presence of ozone-sensitive species and potentially high ozone exposure in southeastern MSAs, no published studies have examined both ground-level ozone and its effect on vegetation in MSAs other than the eastern portion of the Knoxville MSA. …