Ecotoxicological profiling of transect river Elbe sediments

During the river Elbe flood in August 2002, large amounts of suspended organic matter were transported and settled in the course of the river. The aim of this study was to assess the quality of river Elbe sediments using chemical and biological methods. For this purpose 11 samples from river Elbe and 2 from tributaries were investigated. Two contact biotest systems, used to identify the ecotoxic potential of sediments, showed toxic effects in all sediments. Exposure was assessed by quantification of priority pollutants; however, no causal link to biological effects could be established. Effect qualities were characterised by testing organic sediment extracts in a biotest battery consisting of 8 test systems. Test systems varied in sensitivity to detect effects in the samples. Furthermore, samples differed in their ecotoxic potential. An effect-directed analysis was conducted in order to identify compounds responsible for the biological effects. Cause-effect relationships were established for mixtures of polycyclic aromatic hydrocarbons being partially responsible for toxic effects on algal reproduction; however the majority of the cause for toxicity remained unclear. Overall, it has to be concluded that Elbe sediments are not in accord with current quality goals. The chemical and the biological transect profile of the sediments indicate toxicant inputs from Czech Republic, river Mulde and diverse source.