The potential environmental hazard of sediment samples from Copenhagen Harbour was investigated by a combination of chemical analyses and biological tests. The chemical analyses comprised determination of the content of heavy metals, polycyclic aromatic hydrocarbons and polychlorinated biphenyls, and the biological tests comprised whole sediment bioassays with the amphipod Corophium volutator, testing of a sediment suspension with the Microtox Solid Phase test, and testing of sediment pore water by the copepod Acartia tonsa and the alga Skeletonema costatum. For all sediment samples, the concentrations of contaminants exceeded the Probable Effect Levels and toxic effects should therefore be expected. However, various degrees of toxicity were determined by the biotests with the Microtox Solid Phase test system being the most sensitive, the amphipod and the copepod being intermediately sensitive, and no toxicity of the pore water was registered to the algae. Moreover, no direct correlation between the content of the contaminants in the sediment samples and the registered toxicity could be established. It is therefore concluded that the combination of biotesting and chemical analysis is a valuable tool for evaluating the environmental risks of sediments.

The environmental risk assessment of Holmen, a former naval base, included characterisation of the sediments with regard to pollution with xenobiotics, heavy metals, nutrients and bacteria, and ecotoxicity. A simple hydraulic model was established, and the release of substances from the sediment to the water was assessed. Sediment biotests with Corophium volutator and porewater biotests with Skeletonema costatum and Acartia tonsa were conducted. The sediment was characterised as strongly contaminated in the major parts of the investigated area. Based on the application of the acid volatile sulfide method it was concluded that practically none of the heavy metals were bioavailable. Both the sediment and the porewater from a number of stations were toxic. The toxicity did not appear to be attributable to the content of heavy metals, more likely to other contaminants. Furthermore, the sediment, which has served as a sink for accumulation of contaminants over a period of many years, also may constitute a source of contamination due to potential release of heavy metals and xenobiotics from the sediment to the water in some areas. The release appears to give rise to concentrations above the EU Water Quality Objectives at some stations.

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