Three-dimensional contaminant transport/fate model

Management of estuarine and coastal waters requires prediction of contaminant transport and fate with relatively high spatial resolution and complete process descriptions. A recently developed model, referred to as CE-QUAL-ICM/TOXI, combines parts of two previously existing models to satisfy these needs. The transport framework of the eutrophication model, CE-QUAL-ICM, was combined with the toxic substance fate routines of EPA's WASP model. The result is an improved contaminant model that exhibits accurate transport capabilities with widely used fate process descriptions. Additionally, a benthic sediment module was formulated using variable numbers of layers and layer thicknesses to provide improved capabilities for simulating long-term benthic contaminant fate. The contaminant model is indirectly linked to a three-dimensional, hydrodynamic model, CH3D-WES, to drive the water column transport terms of the contaminant model. A dynamic solids balance for the water column and bed can be simulated within the model or read in from a sediment transport model, such as CH3D-COSED. For validation purposes, the model was applied to a flooded limestone quarry dosed with DDE. The model compared favorably against observed data and results from another simpler contaminant model. An application of the model to the New York-New Jersey harbor-estuary system for total PCBs is presented.