This project continues a collobaration with the EPFL (Switzlerland), focusing on the description of physical control mechanisms (near-bottom turbulence) for the oxygen fluxes at the sediment-water interface, taking Lake Geneva as an example. While the colleagues from the EPFL investigate these processes with the help of basin-scale oxygen budgets and local oxygen microprofiling approaches, we attempt to clarify the basic mechanisms with the help of idealized and realistic numerical models. The basic idea is that near-bottom turbulence directly controls the thickness of the diffusive boundary layer, and thus may have a crucial impact on the net oxygen flux into the sediment. Such physical control mechanisms had been largely ignored in previous modeling studies of this type.