Abstract
A mismatch in the awareness of actual ecological effects in the field and predicted effects of chemical stressors is causing erosion in public acceptance of expensive environmental management actions. One should realize that although the pollution peaks in surface waters in the 1970s have now largely subsided due to strict chemical regulations, the problem of pollutants is still with us today. Current total metal concentrations measured in water often predict effects. However deleterious ecological effects are hardly seen in the field. There is a need for models that account for true ecological effects. One of the most promising models in this respect is the recently developed Biotic Ligand Model (BLM) that links water chemistry to the effect concentration of the metal at the target site of toxic action. However, the present BLM has limited applications for multiple metal mixtures and the incorporation of biology lags behind. Therefore, the proposed research aims to develop BLMs for multiple metals, incorporating field-relevant parameters with which to distinguish impaired from healthy aquatic communities. The parameterisation of these multiple-metal models will be done using the latest techniques. The predictions will be underpinned on theoretical grounds, accounting for predominant extrinsic habitat and environmental factors as well as biological factors (intrinsic metal-handling strategies). Comparisons between predictions and field observations will be made and divergences examined. The predictive capacity of the multiple-metal BLM will be validated and lines of evidence are used for results interpretation. The results will ultimately be a basis for environmental risk management. Firstly by underpinning environmental criteria incorporating scientifically sound information on both environmental chemistry and biology. Secondly by exploring active management measures in order to challenge water-quality problems caused by metals in the field and to show the effectiveness of expensive environmental management options.
Netherlands