Water and sediment qualities were investigated in the Oncheon Stream and at the Wondong bridge of the Suyoung River, during the summer rainy season, 2019. Dissolved oxygen (DO) showed the lowest levels at 4.7 and 5.0 m/L, and biogeochemical oxygen demand (BOD) showed the highest at 5.3 mg/L downstream where the tributary flows into the main river. Chemical oxygen demand (COD) increased from 2.0 to 5.9 mg/L on average as it flowed downstream, The COD/BOD ratio decreased gradually as it flowed downstream, reaching 1.0. However, COD/BOD ratio at the Wondong bridge was 5.8-22.2, indicating that easily biodegradable and non-biodegradable organic matter flows into the Oncheon Stream and Suyoung River, respectively. Total nitrogen (T-N) / total phosphorus (T-P) ratio tended to decrease from 72 to 21 as it flowed downstream, measuring 71 to 86 at the Wondong bridge. The water quality index (WQI) generally improved better than grade IV after heavy rainfalls. However, DO and T-P were the parameters that deteriorated the WQI. Ignition loss (IL), COD, T-N, and T-P of sediments had distribution of 1.44 ± 1.01%, 0.35 ± 0.16%, 43 ± 63 mg/kg, and 10.9 ± 21.9 mg/kg, respectively. These were several times lower than the annual averages of IL, T-N, and T-P in 2017 before the dredging project was conducted in the first half of 2018.

Abstract
1. 서 론
2. 재료 및 방법
    2.1. 시료 채취
    2.2. 수질 항목 측정 및 분석
    2.3. 퇴적물 항목 분석
3. 결과 및 고찰
    3.1. 수질 분포 특성
    3.2. 수질지수평가
    3.3. 퇴적물 항목 분포 특성
4. 결 론
REFERENCES

• 이영형(부경대학교 해양학과, (주)대성기술단) | Young-Hyeong Lee (Department of Oceanography, Bukyung National University, Daesung Technology Engineering Co.)
• 문창호(부경대학교 해양학과) | Changho Moon (Department of Oceanography, Bukyung National University)
• 강현정((주)대성기술단) | Hyun-Jung Kang (Daesung Technology Engineering Co.)
• 최성률((주)대성기술단) | Seong-Ryul Choi (Daesung Technology Engineering Co.)
• 김석현(한국해양과학기술원 해양환경연구센터) | Suk-Hyun Kim (Marine Environmental Research Center, Korea Institute of Ocean Science & Technology) Corresponding author