Typical Reservoir Pollution Source Analysis

Exogenous and endogenous pollutions are the two main kinds of pollution sources that result in the deterioration of water quality in reservoirs. Exogenous pollution is derived from the environment surrounding reservoirs, including industrial wastewater, sewage runoff, solid waste, meteoric waters, and surface runoffs from urban, agriculture, and pastoral areas. Endogenous pollution is mainly caused by the pollutants released from sediments, the fecundity and death of phytoplankton and aquatic plants, and aquaculture. The pollution source analysis contributes to a deep research on the mechanism, process, and control of reservoir pollution, and provides basic theory and technology supports for improving the water quality. In recent years in China, with the further understanding about the importance of water protection, especially with the significant progress of water protection, the exogenous pollution of water sources has been or is being effectively controlled. Endogenous pollution becomes the dominant factor affecting water quality. In this chapter, the exogenous and endogenous pollution sources, classification, and status in China are concretely discussed and four reservoirs in China named Jinpen, Shibianyu, Zhoucun, and Fenhe were examined to elaborate these issues. For exogenous pollution, the pollution sources, main pollutants, and the load of every kind of exogenous pollutant in Shibianyu Reservoir were shown to indicate that runoff after rainfall scour was one of the main reasons for TN and TP increase. For endogenous pollution, pollutants release from sediment caused by forward temperature stratification in Heihe Reservoir and backward temperature stratification in Fenhe Reservoir were analyzed. The results showed that temperature stratification would result in the release of nitrogen and phosphorus from sediment. Moreover, endogenous pollution caused by algae reproduction and aquaculture in Zhoucun Reservoir were also discussed point for point and the data indicated that the algae in this reservoir were highly correlated with temperature, pH, turbidity, and total phosphorus, but inversely correlated with the ratio of nitrogen and phosphorus. Decades of cage culture was one main reason for the heavy pollution in sediment of Zhoucun Reservoir.