Dynamic Fugacity Application in Modeling Contaminant Fate and Transport in Rivers

Contaminant transport models in rivers have been studied by many scientists and researchers. Rivers are dynamic systems, with moving water, changing depth and all the interactions occurring within the water column such as; volatilization into air, diffusion between sediment and water column, wet and dry deposition from air to water, deposition of suspended particles onto sediments, resuspension of settled particles back into the water to name some. Generally, concentration has been the choice of parameter to use in these models, but with the addition of sediment and air phases, use of concentration necessitates the use of many partition coefficients and can become very hard to follow as concentration does not follow a continuous profile among phases. However, fugacity follows a continuous profile from one phase to another. Models, which use fugacity as the main parameter, are formulated as a function of the temporal variable ignoring the spatial variations that exists in these applications. The focus of this study is on the incorporation of spatial variability along with temporal variability when fugacity approach is used. The well known advection dispersion equation has been solved with fugacity being the primary unknown in all phases considered. The velocity and depth variability in the river system have been addressed through the solution of Saint-Venant Equations and using the velocity and depth values for each reach as an input into the fugacity based contaminant transport model the fate and transport analysis is completed. The end result is a totally dynamic fugacity water quality model.