摘要 | Vertical distribution processes of sediment contaminants in water were studied by flume experiments. Experimental results show that settling velocity of sediment particles and turbulence characteristics are the major hydrodynamic factors impacting pollutants distribution, especially near the bottom where particle diameter has similar size with vortex structure. Sediment distribution were slowly uniformed along the distance, while contaminants distribution was slightly lagging behind the former. The smaller the initial sediment concentration was, the more time to achieve a uniform concentration distribution for suspended sediment took. Contaminants transportation equation was established depending on mass conservation equations. Two mathematical estimation models of pollutant distribution in the overlying water considering adsorption and desorption were devised based on vertical distribution of suspended sediment: Equilibrium partition model and dynamic micro-diffusion model. The ratio of time scale between the sediment movement and the sorption can be used as the index of the models. When this ratio is large, the equilibrium assumption was reasonable, but when it is small, as the case might require dynamic micro-diffusion model. |