Chemical characteristics of principal PM2.5 species in Chongju, South Korea

Fine particles were collected over four seasons from October 1995 to August 1996 to evaluate the chemical characteristics of principal PM2.5 components in Chongju, South Korea. The annual mean concentrations of PM2.5 (dp 2.5 μm), sulfate, nitrate, ammonium, elemental carbon (EC) and organic carbon (OC) were 44.2, 8.22, 3.63, 2.84, 4.44 and 4.99 μg m−3, respectively. The sum of the species measured from this study accounted for 50–62% of the PM2.5 mass. Sulfate was the most abundant species and constituted 13–23% of the PM2.5 mass. The EC and OC accounted for 17–28% of PM2.5. The correlation between OC and EC was strong, and the annual mean ratio of OC/EC was 1.12, suggesting that OC measured in the Chongju area may be emitted directly in particulate form as a primary aerosol.