Multiphase Distribution of Cohesive Sediments and Heavy Metals in Estuarine Systems

Abstract

Characterization of the types and concentrations of heavy metals in their various phases is needed to assess potential adverse effects on the aquatic environment and its ecosystems, and thereby to assure cost-effective 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 and erosion, heavy metal adsorption and desorption, and the governing hydromechanical transport mechanisms were incorporated in an existing sediment transport model. Formulation and validation of a new relationship for deposition was based on data derived from experiments carried out by previous investigators. The fate and transport of cohesive sediments and associated nickel was simulated for south San Francisco Bay. The comparison of model performance against field observations indicated that the model is capable of representing important phenomena governing the fate of cohesive sediments and associated nickel.