Abstract
The process of mass transfer across the interface between flowing water and bottom sediment is modeled to estimate the release flux of a dissolved substance in bottom sediment. Mass transfer through a diffusive boundary layer just above the sediment is analyzed using the theory of heat transfer. The distribution of solute concentration in the sediment as well as the mass flux at the sediment-water interface is formulated by considering adsorption/desorption between solute and sediment particles in sediment. These analyses yield the relationship of the release flux to flow velocity, adsorption/desorption parameters and physical properties of sediment. By using the values of adsorption/desorption parameters obtained from laboratory experiments, the present model has given satisfactory agreement between the release flux estimated by the model and the one observed in experiments.
