Anwendung differenzierter Untersuchungsmethoden zur Sedimentbewertung

The aquatic sediments have special significance as habitats of species-rich biocoenoses and as the place where manifold transformation processes occur. Because of their high potential for accumulation of contaminants, sediments are particularly sensitive to anthropogenic impacts, which may disturb the natural state of sediments. In order to protect the aquatic life community, such impacts must be identified, assessed, and the chemical causes of toxic effects must be found. Since the end of the 1980s, the interest for a possibly comprehensive assessment of sediments has increased. This problem can be tackled only by an integrated approach, which combines the detection of toxicity under standardized laboratory conditions with chemical data and biologicalin situ studies into a holistic view. The information value of the results depends essentially on the selection of a diversity of test methods, which are able to indicate contaminant effects differentially. This paper presents results from a comprehensive test approach, which integrates standardized methods (DIN) with pore waters and eluates, as well as tests using the whole sediment. To cover a wider variety of contaminants in the sediment, solvent extracts and fractions thereof were also examined by different bioassays. Chemical analyses examined the structural parameters and identified priority contaminants. Non-target screening could detect a variety of further substances and substance classes. The model organisms of the bioassays responded very differentially and sometimes very intensively to the contaminants in the various investigation media. Especially in sediment extracts, some fractions, and consequently also substances and groups of substances, proved to be particularly toxic. It could be shown that the selected chemical, ecotoxicological, and biological study methods contribute to a holistic assessment. Further, possibly very sensitive bioassays and benthos-biological parameters should be examined aiming to optimize the very wide battery of tests.