As a drinking water source of 26 millions people of Seoul metropolitan region, Han river is one of the most important basin.
Managing the Non-point source pollution which is regarded as the main cause of water pollution including refractory
organic matter is important thing. This research investigates the runoff characteristics of organic matters from main 3 rivers
(South Han, North Han, Kyungan). Water quality measurement items include not only carbon-based TOC (Total Organic
Carbon), DOC (Dissolved Organic Carbon), POC (Particulate Organic Carbon) but also R-TOC (Refractory Total Organic
Carbon), R-DOC (Refractory Dissolved Organic Carbon), R-POC (Refractory Particulate Organic Carbon) is researched.
The research shows that R-TOC takes approximately 61∼83% of TOC. Most of the R-TOC is consist of R-DOC (72∼
77%). Refractory organic matter have a stable runoff characteristics compared to other organic matter. The organic matter
concentrations of South Han river and Kyungan river are the highest in spring time and show a gradual decline. The
concentrations of Kyunan river is the highest. Kyungan river’s small area and the high city land use ratio seem to be the
reason. Loading of organic matter in summer time takes the most loading (62∼84%). TOC loadings per unit area of each
river is Kyungan river (1.22 ton/km2), South Han river (1.01 ton/km2), North Han river (0.91 ton/km2).