IMMISCIBLE CONTAMINANT TRANSPORT IN SOILS AND GROUNDWATER WITH AN EMPHASIS ON PETROLEUM-HYDROCARBONS - SYSTEM OF DIFFERENTIAL-EQUATIONS VS SINGLE CELL MODEL

A generalized mathematical model, incorporating the physical, chemical and biological processes which collectively describe the transport of a reactive and immiscible contaminant in soils and groundwater, is presented. The problem is one of multiphase transport, that is, the contaminant can be transported as solutes in water, vapors in air and as unreacted constituents in an immiscible phase. As an alternative, a single cell model as a simplified version of this generalized system is also presented. The whole system is represented by a single element. Such an approach yields conservative estimates of a single constituent contaminant as only advective solute transport is allowed. The model has been applied to study the fate and transport of individual hydrocarbon constituents in an unsaturated zone. Application results are discussed.