To investigate the distribution characteristics of grain size and organic matter of surface sediments from the Nakdong-Goryeong Mid-watershed, surface sediments were collected and analyzed. The samples were collected from six sited at four different times between May 2013 and May 2014. The were analyzed for grain size, water content, ignition loss, chemical oxygen demand, total organic carbon and total nitrogen. The surface sediments were mainly composed of medium sand (mean 44.7%) and coarse sand (mean 32.8%) and became coarser in May 2014. Fine sediments at the site NG-2 were poorly sorted and positively skewed, and occur in a tributary environment that is relatively low-energy compared with the other sites. The water content at the studied sites (15.3 ~ 34.9%) averaged 20.25%, and ignition loss (0.4 ~ 5.8%) and total nitrogen (274 ~ 2493 mg/kg) averaged 1.33% and, 696 mg/kg, respectively. These values indicated that the sediments were not seriously contaminated when compared with the sediment pollution evaluation standard of the National Institute of Environmental Research. The chemical oxygen demand (mean 0.17%) was at the non-polluted level compared with United States Environmental Protection Agency sediment quality standards. The total organic carbon (mean 0.18%) at all sites except site NG-2 (lowest effect level) was the no effect level of the Ontario sediment quality guidelines. The COD/IL (0.02 ~ 0.20) and C/N (0.73 ~ 6.76) were less than 1 and 10, respectively. Organic matter in the study area produced naturally from aquatic organisms. Results of principal component analysis showed that fine sediments (very fine sand and silt) were significantly affected by organic matters (ignition loss, chemical oxygen demand, total organic carbon and total nitrogen). In addition, the highest organic matters content in the study area occurred at the site with the finest sediments (NG-2).

Abstract
 1. 서 론
 2. 재료 및 방법
  2.1. 연구 지역
  2.2. 시료 채취 방법
  2.3. 시료 분석 방법
 3. 결과 및 고찰
  3.1. 입도 분포 변화
  3.2. 유기물질 분포 특성 변화
  3.3. 주성분 분석
 4. 결 론
 REFERENCES

• 김 신(국립환경과학원 낙동강물환경연구소) | Shin Kim (Nakdong River Environment Research Center, National Institute of Environmental Research)
• 안정민(국립환경과학원 낙동강물환경연구소) | Jungmin Ahn (Nakdong River Environment Research Center, National Institute of Environmental Research)
• 김형근(국립환경과학원 낙동강물환경연구소) | Hyounggeun Kim (Nakdong River Environment Research Center, National Institute of Environmental Research)
• 권헌각(국립환경과학원 낙동강물환경연구소) | Heongak Kwon (Nakdong River Environment Research Center, National Institute of Environmental Research)
• 김경훈(국립환경과학원 낙동강물환경연구소) | Gyeonghoon Kim (Nakdong River Environment Research Center, National Institute of Environmental Research)
• 신동석(국립환경과학원 유역총량 연구과) | Dongseok Shin (National Institute of Environmental research)
• 양득석(국립환경과학원 낙동강물환경연구소) | Deukseok Yang (Nakdong River Environment Research Center, National Institute of Environmental Research) Corresponding author