太湖河道水深对底泥营养物质再释放过程的影响

河道中的底泥作为二次污染源,是影响河道水环境重要因素.太湖河口及调水区河流底泥氮磷的释放扩散受水动力条件的影响越来越受到人们的重视.本文用直水槽模拟河道的水动力条件改变,通过实验研究总磷、总氮在不同水深条件下水体中的浓度变化情况,探究底泥中营养物质在不同水深条件下的释放规律.本文从水流底部切应力和底部压强的角度,分析研究上覆水中总磷、总氮的平均释放速率.结果显示上覆水中的总磷随着底部切应力的增大,平均释放速率增大,随着底部压强的增大,平均释放速率减小,即与水深的变化成负相关;总氮则随着底部压强的增大,平均释放速率增大,即与水深的变化成正相关.

Water depth impact on nutrients re-release from sediment in Taihu River Channel

Sediment in the river channel as a secondary source of water pollution, is important for the river water quality. The release of nitrogen and phosphorus from the river sediment at the entrance of Taihu lake and in the diversion area where the hydrodynamic conditions vary the most, has received much attention recently. We developed a flume experiment to explore the impact of the river water depth on the nutrient release from the channel sediment. The concentration of total phosphorus and total nitrogen in the water on top of the sediment were observed over 180 minutes when the water depth in the flume changed from 7.8 cm to 19.2 cm. We found that the average release rate of the total phosphorus from the sediment increased with the increase of bottom shear stress, and decreased with the increase of bottom pressure, illustrating a negatively correlation with water depth. On the contrary, With the increase of the bottom pressure, the average release rate of total nitrogen increased, which was positively correlated with the water depth.