The control of point and non-point source nitrogen to prevent eutrophication of the Nakdong River basin, Korea

Eutrophication of surface waters is commonly caused by excessive inputs of nutrients such as nitrogen and phosphorus. Nakdong River basin was chosen as the study area to investigate the effect of point and non-point source pollution of nitrogen on eutrophication in water body. Non-point source inputs of nitrogen accounted for approximately 84% in the total nitrogen input of the upper Nakdong river watershed, which mainly consists of agricultural land and forests. However, point source inputs of nitrogen accounted for 58~85% in the total nitrogen input of the middle and lower watersheds, including urban area. Therefore, for watershed near urban area, control of point source inputs of nitrogen may be an optimal method to control eutrophication. In this respect, the enforcing reduction of nitrogen in the final effluent of wastewater treatment facilities is needed. On the other hand, to enact more stringent nitrogen regulations, the LOT (limit of technology) and environmental impact should be considered. In this study nitrogen data were analyzed to propose new nitrogen regulations.