PARENT SESSION

2F - Site Specific Testing
Poster Hall
8:30 AM - Monday, 28 April 2003

(MOP/103) Investigations of the Ecotoxicological Hazard Potential and Risk of Erosion of Contaminated Sediments in Lock-Regulated Rivers.

Hollert, H.¹, Duerr, M.², Haag, I.³, Erdinger, L.⁴, Braunbeck, Th.¹, ¹ University of Heidelberg, Dept of Zoology, Heidelberg, Germany² University of Halle, Dept of Hygiene, Halle, Germany³ University of Stuttgart, Dept Hydraulic Engineering and Water Mgnt, Stuttgart, Germany⁴ University of Heidelberg, Dept of Hygiene, Heidelberg, Germany

ABSTRACT- Particle-bound pollutants accumulate in river bottom sediments, which results in a significant decrease of the ecotoxicological availability of toxicants for the majority of aquatic organisms. Under normal hydrologic conditions the release of contaminants from bottom sediments is usually of minor importance. In contrast, flood events may remobilize highly contaminated sediments by in-stream erosion. The objective of this study was to develop a combined ecotoxicological and hydraulic approach to elucidate the ecotoxicological implications associated with the risk of erosion of contaminated sediments. This integrated strategy was applied to the lock-regulated river Neckar in Southern Germany. Both bottom sediment cores and suspended matter of two strong flood events were investigated. Sediment samples below an erosional unconformity showed a sharp increase in the ecotoxicological load. Moreover, it was found that major flood events (HQ5 and higher) could possibly erode even very old, well consolidated and highly contaminated sediments. The suspended matter of the high discharge events investigated (return periods of 15 to 20 years) exerted significantly higher cytotoxicity and mutagenicity than a moderate flood with a 1 year return period. These findings support the conclusion that the observed ecotoxicological effects during major floods may at least partly be due to in-stream erosion of highly contaminated bottom sediments.The study was funded by the state of Baden-Württemberg (FZK-BWPLUS) and supported by the DAAD and a personal grant to H. H. by the Scholarship Foundation of the German People.

Key words: endocrine disruption, cytotoxicity, mutagenicity, erosion risk