This study observed particulate matter (PM2.5 and PM10) in the downtown area of Jeju City, South Korea, to understand the chemical composition of particulates based on an analysis of the water-soluble ionic species contained in the particles. The mass fraction of the ionic species in the sampled PM10 and PM2.5 was 44.3% and 42.2%, respectively. In contrast, in Daegu City and Suwon City, the mass fraction of the ionic species in PM2.5 was higher than that in PM10. The chloride depletion percentage of PM10 and PM2.5 in Jeju City was higher than 61% and 66%, respectively. The contribution of sea-salt to the mass of PM10 (5.9%) and PM2.5 (2.6%) in Jeju City was similar to that in several coastal regions of South Korea. The mass ratio of Cl- to Na+ in the downtown area of Jeju City was comparable to that in some coastal regions, such as the Gosan Area of Jeju Island, Deokjeok Island, and Taean City. The mass fraction of sea-salt in PM10 and PM2.5 was very low, and the concentration of sodium and chloride ions in PM10 was not correlated with those in PM2.5 (R2 < 0.2), suggesting that the effects of sea-salt on the formation of particulate matter in Jeju City might be insignificant. The relationship between NH4 + and several anions such as SO4 2-, NO3 -, and Cl-, as well as the relationship between the measurement and calculation of ammonium ion concentration, suggested that sea-salts may not react with H2SO4, and (NH4)2SO4 may be a major secondary inorganic aerosol component of PM2.5 and PM10 in Jeju City.

Abstract
 1. 서 론
 2. 연구 방법
  2.1. 시료의 채취
  2.2. 시료의 분석
 3. 결과 및 고찰
  3.1. 분석 자료의 정도관리
  3.2. 미세입자의 이온 조성 특성
  3.3. 이온의 오염원 추정
  3.4. 이온의 존재 형태 추정
 4. 결 론
 REFERENCES

• 허철구(제주대학교 환경공학과) | Chul-Goo Hu (Department of Environmental Engineering, Jeju National University)
• 이기호(제주대학교 환경공학과) | Ki-Ho Lee (Department of Environmental Engineering, Jeju National University) Corresponding author