Dissolved organic matter (DOM) is a key component in the biogeochemical cycling in freshwater ecosystem. However, it has been rarely explored, particularly complex river watershed dominated by natural and anthropogenic sources, such as various effluent facility and livestock. The current research developed a new analytical method for TOC/TN (Total Organic Carbon/Total Nitrogen) stable isotope ratio, and distinguish DOM source using stable isotope value (δ13C-DOC) and spectroscopic indices (fluorescence index [FI] and biological index [BIX]). The TOC/TN-IR/MS analytical system was optimized and precision and accuracy were secured using two international standards (IAEA-600 Caffein, IAEA-CH-6 Sucrose). As a result of controlling the instrumental conditions to enable TOC stable isotope analysis even in low-concentration environmental samples (<1 mgC L-1), the minimum detection limit was improved. The 12 potential DOM source were collected from watershed, which includes top-soils, groundwater, plant group (fallen leaves, riparian plants, suspended algae) and effluent group (pig and cow livestock, agricultural land, urban, industry facility, swine facility and wastewater treatment facilities). As a result of comparing characteristics between 12 sources using spectroscopic indices and δ13C-DOC values, it were divided into four groups according to their characteristics as a respective DOM sources. The current study established the TOC/TN stable isotope analyses system for the first time in Korea, and found that spectroscopic indices and δ13C-DOC are very useful tool to trace the origin of organic matter in the aquatic environments through library database.

서 론
분석 원리 및 정도관리
    1. TOC/TN-IR/MS (Total Organic Carbon/Nitrogen -Isotope Ratio Mass Spectrometry, 총 유기탄소/질소 안정동위원소 질량분석기) 소개
    2. 표준물질을 이용한 TOC/TN-IR/MS 분석기기의정밀/정확도 연구
결과 및 고찰: 환경시료에의 적용
    1. 시료 농도 변화에 따른 안정동위원소비의 정밀 · 정확도연구
    2. 기원조사 연구 및 형광 기법과의 비교 검토
적 요
REFERENCES

• 박시영(국립환경과학원 환경기반연구부 환경측정분석센터) | Si-yeong Park (Environmental Measurement and Analysis Center, National Institute of Environmental Research, Incheon 22689, Republic of Korea)
• 최희주(한국산업기술시험원 디지털산업본부 글로벌 시험인증센터) | Heeju Choi (Global Testing and Certification Center, Testing Laboratory, Seoul 08389, Republic of Korea)
• 홍서연(국립환경과학원 환경기반연구부 환경측정분석센터) | Seoyeon Hong (Environmental Measurement and Analysis Center, National Institute of Environmental Research, Incheon 22689, Republic of Korea)
• 임보라(국립환경과학원 환경기반연구부 환경측정분석센터) | Bo Ra Lim (Environmental Measurement and Analysis Center, National Institute of Environmental Research, Incheon 22689, Republic of Korea)
• 최서영(공주대학교 환경과학부) | Seoyeong Choi (Department of Environmental Science, Kongju National University, Kongju 32588, Republic of Korea)
• 김은미(국립환경과학원 환경기반연구부 환경측정분석센터) | Eun-Mi Kim (Environmental Measurement and Analysis Center, National Institute of Environmental Research, Incheon 22689, Republic of Korea)
• 허유정(국립환경과학원 환경기반연구부 환경측정분석센터) | Yujeong Huh (Environmental Measurement and Analysis Center, National Institute of Environmental Research, Incheon 22689, Republic of Korea)
• 이수형(국립환경과학원 환경기반연구부) | Soohyung Lee (Fundamental Environmental Research Department, National Institute of Environmental Research, Incheon 22689, Republic of Korea)
• 김민섭(국립환경과학원 환경기반연구부 환경측정분석센터) | Min-Seob Kim (Environmental Measurement and Analysis Center, National Institute of Environmental Research, Incheon 22689, Republic of Korea) Corresponding author