The relationship between volatile organic profiles and emission sources in ozone episode region—a case study in Southern Taiwan

This study investigates the relationship between volatile organic profiles in the atmosphere and emission sources in an ozone non-attainment in region Southern Taiwan. Dynamometer test of vehicles and stack sampling from industrial facilities were conducted to obtain the fingerprints of emissions from on-road mobile sources and stationary sources, respectively. In addition, field sampling of non-methane organic compounds (NMOC) concentration at monitoring stations during episode seasons were also collected by canisters. The influences of different emissions sources on airborne concentrations were estimated by back-trojectory analysis and chemical mass balance model (CMB 8.0) calculation. Field measurement data indicated that the daily average concentration of NMOC ranges between 26.4 and 69.8 ppb at different sites. The mass fraction for paraffins, oleffins and aromatics in airborne samples at these sites were 28–47%, 7–12% and 41–52%, respectively. Toluene was the dominant species among these species, followed by isopentane, n-butane and 1,2,4-trimethylbenzene. The source apportionment of airborne NMOC in the ozone non-attainment region, based on CMB simulation, is passenger cars (28–51%), motorcycles (9–24%), industrial sources (14–33%), solvent application (13–46%) and biogenic emissions (<1–2.4%), respectively. Both field measurement and model analysis showed that the vehicle exhaust and industrial emission are the dominant contributors of NMOC in the region.