Original Articles
Beibei Chai, Yajiao Li, Tingli
Abstract
Reservoirs are important water sources for most lar ge cities. Many problems are attributed to their th ermal stratification and inherent pollution characteristi cs. So the pollution characteristics of a typical t hermally-stratified reservoir in Xi’an City, China were studied by fiel d investigation and laboratory simulation. The resu lts showed that: (1) The Heihe Reservoir was stably thermally strati fied, particularly during summer months and that th e deeper the water layer, the lower the oxygen concentration. Th us, the bottom layer became completely devoid of ox ygen. (2) The water quality problems of this reservoir were m ainly caused by internal pollutant release from the sediments. (3) The simulation experiment in the laboratory proved that the pollutants in the Heihe Reservoir sediment could be easily released into the overlying water. (4) The s tratification broke up at seasonal changes. Hence, the pollutants released from the sediment transported to the upper layer as the layer became mixed. The pollutants su pplied algae with sufficient nutriment, and harmful algae bloome d accordingly, especially in summer. Thus to destro y the stratification, aerate the bottom layer would be ef fective method to solve the water quality problems for thermally-stratified reservoir.