Aquatic contamination and ecological risk. An attempt to a conceptual framework

The aim of this paper has been to introduce a conceptual model concerning the causal relationships determining the “road between dose and response” of toxic substances in aquatic environments. The paper is focused on metals and utilizes mercury as a type element. The approach puts special emphasis on the environmental factors regulating the potential effects of contaminants and stresses the importance of sedimentology in ecotoxicology. The approach discusses concepts like ecological effect, dose and sensitivity. A potential ecological risk index to be used in practical environmental control programs must also be based upon tested and comparatively inexpensive standard methods. Such an index should account for “biological contact area”, “biological contact time” and “additive effects”. A fundamental concept in this approach is the residual term, which describes the fact that it is impossible in ecological contexts to reach a complete understanding.