An Integrated Approach for Identifying Sources of Pollution: The Example of Cadmium Pollution in the Rhine River Basin

IIASA' s project, Sources of Chemical Pollution in the Rhine Basin, is a comprehensive analysis of the sources of toxic materials in the Basin 1950–2010. The study employs the concept of industrial metabolism. This approach provides a comprehensive view of production and consumption processes and their effects on the environment. It entails a systematic analysis of all sources of a given material, its pathways through the industrial economy, and the mechanisms by which it is transformed into outputs to be adsorbed and processed by the environment. Losses to air, water and soil are estimated. In this paper we present the results obtained for the historical development of cadmium pollution. The historical evolution of cadmium pollution is more or less representative of the overall trends for the other heavy metals. The results indicate that the Rhine river has experienced a significant decline in the load of cadmium over the last 20 years. Another observed trend is that while the absolute load to the river has decreased, the relative shares of the load contributed by point sources and diffuse sources have been reversed compared to 20 years ago. While point sources dominated emissions in the early 1970s, now diffuse sources are more important. These sources may be more difficult to control, however, since they are much more numerous than point sources, are related to dissipative consumptive uses which cannot be easily monitored or regulated, and in many cases the pathways and sources of emissions have not been identified