Interaction between hydrodynamics and mass-transfer at the sediment-water interface

Modeling mass-transfer across the sediment-water interface is a significant issue in environmental hydraulics. In fact diffusional exchanges of solutes between the bed sediment and the overlying water column could greatly affect water quality. Particularly, diffusional flux of dissolved oxygen (DO) towards the bed sediments from the water column could be responsible for low and unacceptable levels of DO in the ecosystem. This flux depends both on sediment and flow characteristics. The objective of the present paper is to investigate the interaction between flow hydrodynamics and dimensionless fluxes of dissolved substances across the sediment-water interface. Therefore, some literature predictive models are compared with experimental laboratory data collected both in flumes and benthic chambers. Also, the influence of turbulent flow features on mass-transfer process is investigated using the available data. These data demonstrated a significant influence of the friction velocity u* on solutes flux for both data sets supporting the assumption that vortices in the near-wall region would affect that flux.