| Popis: |
This contribution summarizes a sediment-water model that is used as a part of a water quality model in a third contribution of this series (Chapter 23). Fluxes of oxygen, ammonia, and nitrate are described between the water column and aerobic, anoxic, and anaerobic zones of the sediments. In the aerobic zone, oxidation of organics and nitrification occurs. In the second layer, denitrification occurs, while in the third layer, anaerobic processes occur. Ammonia sources of nitrification include diffusion from the water column; and internal sediment sources associated with the aerobic oxidation of organics, anoxic nitrate reduction via denitrification, and anaerobic decay. Diffusion of oxygen, ammonia, and nitrate occurs across the sediment-water interface. Temperature effects are modelled using the Arrhenius concept. A combination of zero-order kinetics for nitrate or oxygen consumption with diffusion results in a half-order reaction, with respect to the water column loss rate to sediments. Verification studies are summarized. |
