Source apportionment simulations of ground-level ozone in Southeast Texas employing OSAT/APCA in CAMx

Abstract

Ground-level ozone is a criteria air pollutant which can be transported into an area or produced locally through photochemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOCs) in the presence of sunlight. For an ozone nonattainment area, it is critically essential to know the sources of the observed ozone before a strategic implementation plan can be established for effective reduction of ozone pollution. In this study, source apportionment simulations of ground-level ozone were performed for the Beaumont-Port Arthur (BPA) Area in Southeast Texas employing CAMx (Comprehensive Air Quality Model with Extensions) through its two built-in tools, i.e., OSAT (Ozone Source Apportionment Technology) and APCA (Anthropogenic Precursor Culpability Assessment), involving the 2012 Ozone Episode developed by TCEQ (Texas Commission on Environmental Quality). The OSAT results have indicated that local emission sources play a major role (82%) in the observed local high ozone events in the BPA area; in the meantime, 14% and 4% of the observed ozone have been identified to have transported into the area from the Southwest Louisiana and Gulf of Mexico, respectively. The APCA results have indicated that the Elevated Point, On-road and Low Point emissions are three major anthropogenic sources contributed to the BPA ozone productions with 60%, 19.5% and 19.5%, respectively. The simulation results provide needed information for the development of an implementation plan for effective reduction of ozone pollution in an ozone nonattainment area.