Ecotoxicological impact of re-mobilized sediments and flood events for lock regulated rivers and wetlands
Abstract: In recent years, sediments have become a central topic of scientific and public discussion as an important factor for determining water quality. While the quality of surface waters in Germany has significantly improved during the past years, highly contaminated sediments still create a considerable threat to the quality of several European catchment areas. For several European river basis, including Neckar, Rhine and Elbe, highly contaminated old sediments can be described as “potential chemical time bombs”. An important process which may remobilize such sediments and which is still of increasing importance in relationship to the global climate change is more often occurrence of stronger floods in Europe as well as in other parts of the world. To understand and predict possible toxicological and ecotoxicological consequences of contaminants mobilized from sediments by flood events it is necessary to develop scientific approaches for the assessment of regularly flooded rivers. The combination of hydrodynamics and ecotoxicological investigations is devolving to an emerging field of research. Recently, it was shown that hydrodynamic aspects can be involved as additional line-of-evidence in Weight-of-evidence studies assessing the impact of sediments. In the last decade several studies were published addressing the ecotoxicological impact of flood events or using combined approaches for evaluating flood events and the risk of erosion. Here, we summarize different concepts and case studies for the assessment of sediment quality and report on some novel integrative test methods for assessing sediment toxicity including contaminant re-mobilization during simulated re-suspension events. Within the talk several case studies addressing the ecotoxicological impact of re-mobilized sediments and flood events for look regulated rivers and wetlands are presented. Combined investigations of sediment contamination and mobility as well as acute and mechanism specific biotests in effect directed analyses/weight-of-evidence studies show great potential for the assessment of chemically polluted rivers and should be included into the 'programmes of measures' within future management concepts.