分层型城市水源水库水质污染及成因分析

By taking Heihe Reservoir, which is the uppermost water source of Xi’an city in China, as the main research object, and by taking the physiographic condition and hydraulic characteristics of the reservoir into consideration, water quality monitoring and analysis were carried out ranging from the representative sections of upper streams of the reservoir to the representative points in the reservoir. It was preliminarily determined that the water pollution of Heihe Reservoir was directly caused by the internal pollution, ie, by pollutants release from the sediment. Water quality monitoring and analytical results show that the water quality indexes, such as ammonia, total nitrogen, iron and manganese in upper streams did’t exceed the contemporaneous monitoring values of the reservoir, meanwhile the stable thermal stratification in Heihe Reservoir and the strong reduction conditions resulted from oxygen consumption of water body and sediments led to a significant release of pollutants from the reservoir sediments. Therefore, it can be concluded that the external pollution is the precondition of the internal pollution and the internal pollution directly leads to water pollution of Heihe Reservoir at present.