自然与引水因素对受纳水体自净作用的影响研究

Effects of Natural and Water Diversion Factors on Self-purification of The Receiving Waters

以嘉兴河道底泥和河水为研究对象,以上覆水中氮的存在形态及浓度作为考察指标,通过小试实验模拟了实际受纳水体在四种自然/引水条件(底泥是否存在、复氧与否、不同流速和温度)下的自净过程。结果表明:在无大气复氧条件下,厌氧微生物活性较高而好氧微生物活性较低,使得氨态氮在底泥中厌氧微生物的活动下大量释放积累并影响了其硝化作用及好氧反硝化作用。低温下底泥和上覆水中微生物的活性均较低,氮的释放及转化均受影响。因此,在引水工程中可增加跌水等工程以增加受纳水体的复氧能力,夏天引水时可适当减少引水时间和流量,延长引水周期。

In order to investigate the effect of the water diversion on the self-purification of the receivingwater, bench-scale experiments using the nitrogen nutrients as water quality index were conducted andfour influencing factors （sediment, reaeration, flow velocities and temperature） were evaluated. Thesediment and model water used in experiments were withdrawn from Jiaxing rivers. The results suggestthat river sediment can release the pollutants to the overlying water, which results in the accumulation ofnitrogen and reduction of the conversion efficiency, but decrease in TN content of the overlying watermay be obtained. Rearation can significantly promote the nitrogen transformation, revealing that waterfall could be a choice for improving the self-purification capacity of overlying water. Increasing velocityis able to improve dissolved oxygen in the overlying water, but also lead to the sediment resuspensionand pollutant release. The water temperature is positively related to the nitrogen conversion. It can beconcluded that short diversion time, a smaller water diversion flow rate and a longer diversion interval insummer benefit the self-purification of receiving water.