The ambient mass concentration and chemical composition of the PM2.5 were determined at the highland site with 1,100 m above sea level on Jeju Island from June 2013 to November 2014. Yearly averaged mass concentration of PM2.5 was 11.97±8.63 /m3. PM2.5 concentrations were highest during the spring, while they tended to be lowest during the summer. Eight water soluble ionic species attributed 45.5% to PM2.5 mass. SO4 2-, NO3 - and NH4 + were major ions, which occupied to 27.9%, 3.7% and 12.3%, respectively. The greatest contributors to total mass concentration of water-soluble ions contained in PM2.5 were sulfate, ammonium and nitrate. These three ions accounted for 96.6% in total ions mass concentration of PM2.5. We could infer that these three secondary ions exist mostly in the form of (NH4)2SO4 and NH4NO3. Ca2+ and Mg2+ had a good relationship and with r=0.9. The molar ratio of Mg2+/Ca2+ in this study was lower than the value observed in sea water and higher than that in soil dust, indicating that these two ions originated from other sources rather than ocean and soil dust in this study.

Abstract
 1. 서 론
 2. 재료 및 방법
  2.1. 시료채취지점
  2.2. 측정 및 분석
 3. 결과 및 고찰
  3.1. PM2.5의 질량농도
  3.2. 입자상물질에서의 수용성 이온의 조성
 4. 결 론
 감사의 글
 REFERENCES

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