Choi, J; Heo, J; Ban, S; Yi, S; Zoh, K
We examined the characteristics, sources, and distribution of PM2.5 and carbonaceous species in particulate samples collected from June 2009 to May 2010 in Incheon, Korea. The average PM2.5 concentration (41.9 +/- 9.0 mu g m(-3)) exceeded the annual level set by the United States' National Ambient Air Quality Standards (15 mu g m(-3)). The major fraction of PM2.5 consisted of ionic species (accounting for 38.9 +/- 8.8%), such as NO3-, SO42-, and NH4+, as well as organic carbon (OC) (accounting for 18.9 +/- 5.1%). We also analyzed the seasonal variation in PM2.5 and secondary aerosols such as NO3- and SO42- in PM2.5. While SO42- concentrations were higher in spring and summer, the concentration of PM2.5 and NO3- were the highest in winter. SO42- concentrations were higher during the spring and summer, but PM2.5 and NO3- were highest during the winter. As an important aerosol indicator, water-soluble organic carbon (WSOC) (mean 4.7 +/- 0.8 mu g m(-3), 58.9 +/- 10.7% of total OC) showed a strong relationship with NO3-, SO42- and SOC (R-2 = 0.56, 0.67, and 0.65, respectively), which was indicative of favorable conditions for SOC formation during the sampling period. Among the individual organic aerosols measured, n-alkanes, n-alkanoic acids, levoglucosan, and phthalates were major components, whereas PAHs (polycyclic aromatic hydrocarbons), oxy-PAHs, hopanes, and cholestanes were minor components. The concentration of organic compounds during smoggy periods was higher than during non-event periods. The n-alkane and n-alkanoic acid species during the smoggy periods were 10-14 times higher than during the normal period. Using principal component analysis coupled with multiple linear regression analysis, we identified the primary sources of PM2.5 to be motor vehicle/sea salt, secondary organic aerosols, combustion, biogenic/meat cooking, and soil sources. (c) 2012 Elsevier Ltd. All rights reserved.