AN INTEGRAL APPROACH TO SUPPORT MANAGERIAL ACTIONS ON MICROPOLLUTANTS IN THE SOUTHERN NORTH-SEA

During the last decades the southern part of the North Sea has been exposed to high inputs of micropollutants from various sources. Within the framework of the project Management Analysis North Sea (MANS), studies have been carried out to quantify the impact of anthropogenic pollution inputs on coastal water quality, sediments and biota. In order to study the effects of different managerial actions an integrated modelling framework has been developed to enable a spatial evaluation. In this regard special attention has been given to: the reduction of river inputs, as a result of domestic and industrial waste water treatment the storage of dredging sludge from the Rhine-Meuse estuary. It is shown by the results of this study that input reductions of heavy metals since 1980 have resulted in a significant reduction of concentrations in Dutch coastal waters. Long-term simulation of accumulation of pollutants in the sediment, however, showed that due to the long time scale the reduction of the seabed can take several decades. Similar conclusions can be drawn for organic micropollutants, although the input reductions seem to be less pronounced. Based on bioaccumulation modelling, the pollution of the sediment proved to be an important source for uptake of micropollutants in the food web. This study also made clear that significant reductions of North Sea pollution can be established if combined actions are taken. Reduction of pollutants from the Rhine-Meuse estuary, together with the storage of polluted dredging sludge from the Rotterdam harbours, will result in a significant reduction of the state of pollution of the coastal waters of the Netherlands.