Fractionation of secondary organic carbon in aerosol in relation to the trafficborne emission of semivolatile organic compounds

The environmental behavior of particle-bound secondary organic carbon (SOC) was investigated with respect to its fractionation at four urban sites in Seoul, a megacity in Korea from Feb to Dec 2009. Empirical estimates of SOC formation were comparatively evaluated using the multiple linear regression and constrained mass balance (i.e., CO and EC tracers) methods. The SOC fraction estimates were significantly different depending on the applied methods. The multiple linear regression method used for the estimation of SOC fraction was more reliable than the constrained mass balance approach due to the limited number of available daily PM measurement during each season. Seasonal and spatial patterns in the SOC fractions were examined at the four urban sites. Seasonally averaged SOC fractions ranged from 15 to 65% of the total organic carbon concentration. According to this study, the SOC fractions were significantly high in the spring and summer relative to other seasons.