Comparable Study on the Chemical Characteristics of PM_2.5 Measured in Chuncheon and Wonju, Gangwon-do

In this study, PM_2.5 and its major chemical constituents were measured in two different cities in South Korea. One monitoring site is located in Chuncheon, where there are no large anthropogenic sources, and the other monitoring site is located in Wonju, where the emission rates of most air pollutants including PM_2.5 are higher than those in Chuncheon. During the study period, concentrations of PM_2.5 mass and ionic compounds were higher in Wonju while carbonaceous compounds were more abundant in Chuncheon. NO₃ ^- and organic carbon (OC) showed the highest concentration in Wonju and Chuncheon, respectively. There was statistically significant correlation between OC and elemental carbon (EC) in Chuncheon, but no correlation was observed between two species in Wonju. In Wonju, OC was enhanced with northerly winds while EC increased with westerly winds, suggesting that OC and EC were emitted (or secondarily produced) from different sources. For high concentration episodes (HCEs) observed in Chuncheon, NO₃ ^- and OC increased the most, and their increment ratios were much higher than in Wonju, indicating that secondary inorganic and organic formation was significant for enhancing PM_2.5 concentration in Chuncheon. In Wonju, NO₃ ^- 49 was the most important species during HCEs, but the increment of OC was not notable.