title: Partitioning-based dosing: an approach to include bioavailability in the effect-directed analysis of contaminated sediment samples.
abstract: One of the major challenges of effect-directed identification of hazardous chemicals in sediments is the appropriate consideration of bioavailability for a hazard-based prioritization of fractions and toxicants. The equilibrium partitioning approach is frequently used to estimate the bioavailability of sediment contaminants. To simulate partitioning ofthe constituents of complex sediment contaminations in the sediment-water-biota system, a new dosing technique based on silicone elastomer stirrer bars (silicone rods) for use in a growth inhibition test with the green algae Scenedesmus vacuolatus was developed. The dosing technique has a high loading capacity and a fast achievement of equilibrium (5-50 min) for a broad range of model compounds. The subsequent delivery of compounds stored by the silicone during the bioassay compensates possible losses of compounds and keeps the concentrations constant. Furthermore, a dose-dependent response is achieved for single compounds and complex mixtures from sediment extracts. The extracts of three sediment samples from the Elbe River Basin were fractionated using a multistep HPLC method and investigated in the bioassay using conventional DMSO dosing and loaded silicone rods. The results of the toxicity test clearly show that the toxicity patterns are quite different for the two dosing techniques, whereas the differences between the sampling locations are less pronounced. We suggestthat partitioning-based dosing better reflects exposure in sediments and thus provides a more realistic identification of key toxicants.
authors: Department of Effect-Directed Analysis, UFZ-Helmholtz Centre for Environmental Research, Permoserstrasse 15, 04315 Leipzig, Germany. nicole.bandow@ufz.de
authors: Nicole
authors: N
authors: Bandow
authors: Rolf
authors: R
authors: Altenburger
authors: Urte
authors: U
authors: Lübcke-Von Varel
authors: Albrecht
authors: A
authors: Paschke
authors: Georg
authors: G
authors: Streck
authors: Werner
authors: W
authors: Brack
mesh_terms: D001681:Biological Assay; D001682:Biological Availability; D056890:Eukaryota / Q000187:drug effects / Q000254:growth & development; D019015:Geologic Sediments / Q000032:analysis*; D007700:Kinetics; D012989:Soil Pollutants / Q000032:analysis* / Q000633:toxicity; D013997:Time Factors; D018675:Toxicity Tests
chemical_list: D012989:Soil Pollutants