河流底泥冲刷悬浮对水质影响途径的实验研究

进入天然水体的大部分污染物会在河流，湖泊底部形成富含各种污染物的沉积物层，在一定的水流流速及紊动作用下发生底泥冲刷及再悬浮。大量的污染物被重新释放出来造成河湖水体的二次污染，这种情况是外源污染得到治理后影响水质的主要因素。建立这种影响条件下的水质模型需要对沉积物的污染释放机理有充分的认识。采用富含污染物的天然河湖底泥，通过衡温静态培养等手段，在不同的水力条件。瞬彰服，连续悬浮和静止状态下，研究了污染物的释放，并对实验结果进行了分析。确定了底泥冲刷悬浮影响水质的主要途径，即在底泥间隙水污染物浓度接近平衡时，其与上层大水体的混合作用是影响水质的主要作用，其次是下部底泥的静态释放，而悬浮颗粒的污染物扩散释放作用则较小，这为底泥冲刷悬浮影响下的水质模型的建立提供了理论依据。

EXPERIMENTAL INVERSTIGATION OF IMPACT WAY OF SCOURING AND SUSPENDING OF RIVER BOTTOM SEDIMENT ON WATER QUALITY

Most pollutants entering natural water system may be absorbed onto suspended solid particles and sediment.At the bottom sediment-containing contaminant layer is normally observed. At certain velocity of flow, the bottom sediment can be scoured and suspended and most pollutants released into water body. When the entrance of outside pollution resources become ceased,the release will become the most important factor influencing water quality. So, it is thus significant to establish mathematical models to distinctly understand the process of the pollutant releasing from bottom sediment.Some different hydraulic conditions were used for such purposes : instant mixing, continuous suspending and stilly being. Contaminant dispersion from river and lake bottom sediment was simulated and the main impact ways of sediment on water quality were ascertained. When bottom sediment suspending, the pore water in foregone sediment is released and mixed with the water body, and the water quality changes significantly. At same time, the sediment on water bottom will release contaminant steadily, but it is affected by many factors. Because the role of suspended sediment particle is much less than that of pore water in sediment, it can be ignored in developing the water quality model.