Receptor modeling of VOCs, CO, NOx, and THC in Taipei

An empirical receptor model based on Markov Chain Monte Carlo simulation was applied to one-year measurements of eight VOCs, CO, NOx, and THC collected in Taipei during 1993. Ambient monitoring data were measured at four monitoring stations in Taipei metropolitan. Among five VOC-based sources (motorcycles, catalyst passenger cars, non-catalyst passenger cars, diesel vehicles, and gasoline vapor), non-catalyst passenger cars had the greatest contributions to eight VOCs (53–61%; 90.0–220.3 μgm−3). Among seven sources based on CO---NOx---THC emissions (catalyst and non-catalyst two-stroke motorcycles, four-stroke motorcycles, catalyst and non-catalyst passenger cars, diesel vehicles, and gasoline vapor), passenger cars had the greatest contributions to NOx (50–63%; 0.05–0.26 mg m−3), motorcycles had the greatest contributions to CO (70–76%; 0.81–4.97 mg m−3) and gasoline vapor contributed substantially to THC (17–58%; 0.35–0.85 mg m−3). Our empirical receptor models have successfully improved the estimation of source coefficients for VOCs, CO, NOx, and THC by partially solving the collinearity problems among various mobile source profiles. Such an improved methodology is useful for validating source inventory and managing air quality in metropolitan areas.