A model for diagnostic analysis of estuarine geochemistry

Abstract

A new numerical model for the fate and transport of nonconservative metals in an estuarine environment is introduced. ELAmet solves the depth‐averaged advection/dispersion/transformation equation on a two‐dimensional grid using a finite element formulation in an Eulerian‐Lagrangian framework. The model incorporates aqueous speciation and adsorption/desorption. Adsorption to any number of solid types can take place through linear (partitioning) reactions or nonlinear (complexation) reactions. The model accommodates chemical equilibria and kinetics simultaneously. Rate constants can span any range of time scales, as the computational time step for solving the chemical transformation equations has been decoupled from that dictated by the circulation. Verification of the model is included for a one‐dimensional channel and up to 15 chemical species. Preliminary applications are included which illustrate the concept of diagnostic modeling for a synthetic estuarine system in which the effects of source location, chemical kinetics, and sediment deposition on the mixing plot are examined.