Abstract
A model for diffsional mass transfer of dissolved substance from bottom sediment to flowing water is formulated as a function of flow velocity and characteristics of the sediment such as water content of sediment and amount of dissolved substances contained in sediment. Laboratory experiments are carried out in order to verify the proposed model. The experimental results have shown that the mass flux increases as the flow velocity increases. The mass flux is influenced by water content of sediment as well as amount of dissolved substances contained in sediment. It is also found that the adsorption process between methylene blue and kaolinite is expressed by Langmuir isotherm equation, and it enables us to estimate a concentration of dissolved substance at the sediment-water interface. The release rate of dissolved substances estimated by the present model is in good agreement with that observed in the experiments.
