This study investigated the nitrate formation process, and mass closure of Particulate Matter (PM) were calculated over the urbanized area of Jeju Island. The data for eight water-soluble inorganic ions and nineteen elements in PM2.5 and PM10 were used. The results show that the nitrate concentration increased as excess ammonium increased in ammonium-rich samples. Furthermore, nitrate formation was not as important in ammonium-poor samples as it was in previous studies. According to the sum of the measured species, approximately 45~53% of gravimetric mass of PM remained unidentified. To calculate the mass closure for both PM2.5 and PM10, PM chemical components were categorized into secondary inorganic aerosol, crustal matter, sea salt, trace matter and unidentified matter. The results by the mass reconstruction of PM components show that the portion of unidentified matter was decreased from 52.7% to 44.0% in PM2.5 and from 45.1% to 29.1% in PM10, despite the exclusion of organic matter and elemental carbon.

Abstract
1. 서 론
2. 재료 및 방법
    2.1. 측정 지점 및 시료 채취
    2.2. 시료의 분석
3. 결과 및 고찰
    3.1. 미세먼지 질량농도 및 성분별 특성
    3.2. 질산염의 생성
    3.3. 미세먼지의 질량 재구성
4. 결 론
REFERENCES

• 이기호(제주대학교 환경공학과) | Ki-Ho Lee (Department of Environmental Engineering, Jeju National University)
• 김수미(제주특별자치도 보건환경연구원 대기환경과) | Su-Mi Kim (Air Environmental Division, Jeju Special Self-Governing Province Research Institute of Health & Environment)
• 김길성(제주특별자치도 보건환경연구원 대기환경과) | Kil-Seong Kim (Air Environmental Division, Jeju Special Self-Governing Province Research Institute of Health & Environment)
• 허철구(제주대학교 환경공학과) | Chul-Goo Hu (Department of Environmental Engineering, Jeju National University) Corresponding author