| Title |
Phosphorus loadings from watershed and fishfarms into Lake Daechung and the phosphorus budget |
| Authors |
이기종 ; 허우명 ; 김범철 ( Ki Jong Lee ; Woo Myung Heo ; Bom Chul Kim ) |
| Abstract |
Phosphorus loading into Lake Daechung was estimated by determining the phosphorus input via runoff from drainage basin and the phosphorus discharge from floating-net fishfarms. The loading from drainage basin was determined by measuring total phosphorus concentration in the four main inflowing streams on the monthly base. Phosphorus loading was concentrated in rainy seasons due to higher phosphorus concentration and higher flow rate. Phosphorus discharge from the dam was also high in August and September because of the discharge of intermediate turbid layer formed by storm runoff. P loading via four sites were 52, 32, 27, and 4 tP/yr for Kumkang, Suhwachun, Bochungchun, and Kusin, respectively. Phosphorus discharge of fishfarms was estimated from the amount of fishfeed applied annually and the unit rate of phospohrus excretion per feed weight. The loading from the watershed and fishfarms were calculated to be 138 and 35 tP/yr, respectively. The phosphorus loading of Lake Daechung far exceeded the critical loading for eutrophication. The amount of phosphorus discharge through outflowing water was 46 tP/yr. Thus the retention rate of phosphorus was 0.73. |