Conclusions

Analysis of the chemical "metabolism" of modern industrialized societies is very complex, requiring a sophisticated systems approach. Nevertheless, studies tracking the flow of toxic materials through the economy and into the environment can be an indispensable tool for environmental management.

Studies of the Rhine Basin are of particular interest because the region has passed through the phase in which high productivity is associated with correspondingly high levels of polluting emissions, into a phase where production has been partially decoupled from pollution. Understanding the societal, economic, and technological driving forces that stimulated this transition could provide a blueprint for the clean-up of river basins that are currently trapped in the coupled production-pollution syndrome - and there are many of them in the world today. The insights provided by our study, together with studies of the industrial metabolism of highly polluted regions such as Eastern Europe, could provide a basis for the rational prioritization of actions required for restoring the environment to an acceptable level.

Furthermore, the Rhine Basin study has demonstrated that even regions in a more advanced stage of environmental management could benefit from such studies. Indeed, "input management" (e.g. Odum, 1989), rather than "fire brigade actions," will be of increasing importance in formulating action alternatives that are better integrated and more directed toward the goals of long-term economic and ecological sustainability.

Finally, it should be noted that one of the most useful functions of soils and sediments is their ability to serve as a "sink" for the retention of toxic chemicals. This sink, however, usually has a finite sorption capacity, the size of which is governed by fundamental chemical properties such as pH, organic matter content, etc. So far, hardly any information is available regarding the long-term. broad-scale cumulative loadings of toxic chemicals into the environmental sinks, and on whether, and under what conditions, the sorption capacity might be transgressed beyond a threshold value considered safe for the environment and for human health. We believe that the analysis presensed in this chapter illustrates the usefulness of our approach in evaluating long-term environmental impacts.