Measurements and Modeling of Regional Air Quality in three Southeast United States National Parks

Abstract

Since the passage of the 1970 Clean Air Act (CAA), regulatory efforts to comply with the 0.12-ppmv National Ambient Air Quality Standard (NAAQS) for O₃ have proved inadequate [(NRC); Dimitriades, 1989]. O₃ nonattainment continues to be a problem, especially in the southeast United States. This is attributed to the oxidation of NO_x in the presence of excessive amounts of biogenically emitted VOCs such as isoprene [Trainer et al., 1987; Chameides et al., 1988]. The new 8- hour O₃ National Ambient Air Quality Standard (NAAQS) (0.08 ppm) is likely to bring more suburban and rural locations into noncompliance [Chameides et al., 1997]. Biogenic VOCs emitted by vegetation [Fuentes et al., 2000; Fehsenfeid et al., 1992; Lamb et al., 1993] and anthropogenic VOCs emitted by human activities are both widely present in rural aTeas [Kang et al., 2001; Hagerman et al., 1997]. Previous studies indicate that the influence of these VOCs on important aspects of atmospheric chemistry such as O₃ production can be significant [Trainer et al., 1987; Chameides et al., 1988]. Clearly, if O₃ concentrations are to be successfully controlled by implementation of control on primary pollutant emissions, the roles of both natural and anthropogenic VOCs in these rural areas must be thoroughly understood. However, our understanding of O₃ and VOC budgets in rural areas is still very limited. Emissions of biogenic VOCs as well as the roles of both biogenic and anthropogenic VOCs in O₃ production in rural areas are largely uncharacterized [Guenther et al., 2000].