The modelling part (activity 7) will result in a tool that describes the pathways of pollutants in our Belgium coastal zone. Pollutants are either dissolved in the water column, attached to small sediment particles (usually the silt fraction) or residing in the bed sediment (in particulate or dissolved form). The following scheme represents how pollutants shift between the three different states

The partition coefficient is an empirical derived parameter specific for our coastal zone and it determines the balance between dissolved and particulate phase. It is experimentally derived and delivered in the framework of activity 2, activity 3 and activity 4.  The balance between the phases is different for each pollutant type so the modelling scheme is adapted to the pollutant class in collaboration with the experts of the different activities. The balance between dissolved and bed sediment state is determined by diffusion processes. Between particulate and bed sediment state sinking and resuspension of particles plays a role

The dissolved phase of the pollutant moves according to hydrodynamic forces active on our coastal waters, the particulate phase behaves as sediment in water. Inside the bed sediment, dissolution and attachment processes play in the pores of the sediment, but this will only be modelled indirectly. To describe the dynamics of each phase, we make use of a coastal shelf sea model set up COHERENS.

In collaboration with activity 1 this conceptual view of pollutant pathways will be validated with real time measurements and if the model is strong enough it can be used as a predictive tool for pollution fate prediction or pollution origin prediction.