Seasonal Variation of PM2.5 and Its Major Ionic Components in an Urban Monitoring Site

The ionic composition of PM2.5 samples was investigated by their datasets of cationic (Na+, NH4+, K+, Mg2+, and Ca2+) and anionic components (Cl-, NO3-, and SO42-) along with relevant environmental parameters collected from an urban monitoring site in Korea at hourly intervals in 2010. The mean (and SD) annual concentration of PM2.5 was computed as 25.3 μg m-3 with the wintertime maximum. In addition, sum concentrations (neq m-3) of five cationic species (291) were slightly lower than 3 anionic species (308). Most cations exhibited the highest seasonal values in spring, while anions showed more diversified seasonal patterns. According to PCA, five major source categories were apparent with the relative dominance of secondary inorganic aerosols (SIA). The results of our study suggest consistently that the distribution of ionic constituents in an urban area is affected by the combined effects of both natural and anthropogenic processes.