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 Basi n 1950-2010. The study employs the concept of industrial metabolism. T his approach provides a comprehensive view of production and consumpti on processes and their effects on the environment. It entails a system atic 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 res ults obtained for the historical development of cadmium pollution. The historical evolution of cadmium pollution is more or less representat ive of the overall trends for the other heavy metals. The results indi cate that the Rhine river has experienced a significant decline in the load of cadmium over the last 20 years. Another observed trend is tha t while the absolute load to the river has decreased, the relative sha res 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 ar e much more numerous than point sources, are related to dissipative co nsumptive uses which cannot be easily monitored or regulated, and in m any cases the pathways and sources of emissions have not been identifi ed.