Stormwater runoff is a major source of nonpoint source pollution, contributing 22-40% of the total pollution load in 4 major rivers, which has a significant impact on aquatic ecosystems. The criteria for installation of nonpoint pollution abatement facilities in Korea focuses on the removal of suspended solids. Since the load of dissolved phosphorus and heavy metals in stormwater runoff is increasing, it is necessary to develop a method to reduce dissolved materials as well. In this study, the efficiency of using clay granule, zeolite, blast furnace, and basic oxygen furnace slag (from lab-and pilot-scale experiments) to remove SS, phosphorus, and heavy metals from surface waters was evaluated. Among the four types of filter media, the removal performance of clay granule for SS and basic oxygen furnace slag for phosphorus and heavy metals was excellent. As a result, the clay granule and basic oxygen furnace slag were selected as the filter media. In the pilot column test, 89.5% of SS, 77.6% of phosphorus, 87.3% of Zn, and 67.5% of Cu was removed, indicating stable removal efficiency, with a head loss of 3.8 cm. It satisfied the nonpoint pollution abatement facility installation criteria of functioning at a linear velocity 20 m/h. The clay granule and basic oxygen slag filter would be a useful addition to a nonpoint pollution abatement facility.

The seasonal variation of phytoplankton communities and its standing crops in accordance with environmental factors were investigated at Yeongrang-ho, Cheongcho-ho, Mae-ho and Hyang-ho which are located in the East coast of Korea during April to October 2011. High concentrations of T-N and T-P were observed in four lagoons due to the inflowing nutrients from farmlands and residential areas near lagoons. Nutrient salts mainly composed of nitrogen and phosphate caused the eutrophication of the lakes, leading to the robust growth of phytoplankton. During the period of investigation, 64 to 107 taxa of phytoplankton were observed in four lagoons. Diatoms were the most dominant species with high density. Non-point pollution source was estimated as the main cause of water pollution of lagoons. Trophic states of lagoons evaluated using the value of TSI and TSIKO indicated that all the investigated lagoons were in the eutrophication state.