Reasons of Water Quality Variation and Eutrophic of a New Reservoir

After water storage of Laohutan reservoir, nitrogen (TN), total phosphorus (TP) and ammonia nitrogen (NH₃-N) are the main pollutants. In the first month of water collection, the vertical distribution of TN, TP and NH₃-N concentrations is increased distinctly from the surface layer to the bottom layer. It shows that the reservoir water quality is affected by pollutants released from submersed soil. However, the soil release ability decreased with run of the reservoir and a new balance came into being. The water quality of the inflowing stream is main factor to affect Laohutan reservoir. After water storage, the concentrations of TN and TP exceeded the national standard for drink water in 1# stream, which deteriorated the reservoir water quality. Just about four months later, the high concentration of TP in 1# stream caused eutrophic of the reservoir and cyanobacteria bloom. Therefore, the control and improvement of inflowing water quality are dominant measure to prevent the eutrophication of reservoir and to assure the water supply safety.