MULTIPHASE DISTRIBUTION OF COHESIVE SEDIMENTS AND HEAVY-METALS IN ESTUARINE SYSTEMS

Characterization of the types and concentrations of heavy metals in th eir various phases is needed to assess potential adverse effects on th e aquatic environment and its ecosystems, and thereby to assure cost-e ffective mitigation and waste-allocation strategies. A two-dimensional vertically averaged finite-element model was extended to predict the spatial and temporal distribution of cohesive sediments and associated toxic heavy metals as a result of a pollutant input into an estuarine system. Constitutive relationships for cohesive sediment deposition a nd erosion, heavy metal adsorption and desorption, and the governing h ydromechanical transport mechanisms were incorporated in an existing s ediment transport model. Formulation and validation of a new relations hip for deposition was based on data derived from experiments carried out by previous investigators. The fate and transport of cohesive sedi ments and associated nickel was simulated for south San Francisco Bay. The comparison of model performance against field observations indica ted that the model is capable of representing important phenomena gove rning the fate of cohesive sediments and associated nickel.