A numerical model is presented for simulating the transport of toxic pollutants in rivers, estuaries and seas. The numerical model is based on a finite volume approach and consists of different sub models:
A hydrodynamic module for describing river water flow, tidal flows, sea currents, etc.;
A module for simulating the transport of dissolved chemicals and suspended particles, including dispersive mixing due to turbulence; · A module for sediment transport, incorporating erosion and resuspension processes;
A module for simulating the transport of sorbing toxic pollutants, using simulation results and information obtained with previous modules.
The model is applied to the river Schelde (Belgium), the Schelde estuary (The Netherlands), and the sea along the Belgian coast. Simulation results are presented for several heavy metals and organic micro pollutants, as PCBs, proving the importance of particulate matter. In particular, it is shown that sorbing chemicals tend to accumulate in the estuarine sediments, while only little amounts are reaching the sea. In addition, it is found that the mobility of heavy metals is strongly influenced by salinity, and that the mobility of organic pollutants depends upon complexation with dissolved organic matter.
