Characteristic levels of chlorinated hydrocarbons and trace metals in fish from coastal waters of North and Baltic sea.

During investigations on the occurrence and distribution of contaminants in coastal waters of the North Sea and the Baltic organochlorine compounds such as hexachlorobenzene (HCB), octachlorostyrene (OCS), hexachlorocyclohexane isomers (HCH), dichlorodiphenyltrichloroethane (p,p'-DDT) and its metabolites and polychlorinated biphenyls (PCBs) and heavy metals such as mercury, cadmium and lead were determined in a selected flatfish species (flounder, Platichthys flesus L.). The sampling network covered the outer estuaries of the rivers Weser and Elbe, the German Bight, the Danish North Sea coast and coastal regions of the south-western Baltic. Organochlorine compounds were determined by high-resolution glass capillary gas chromatography with electron capture detector after sample pretreatment and clean up. For the determination of heavy metals a multi-stage analytical procedure was used, in which graphite furnace (for Cd and Pb) resp. cold vapour (for Hg) atomic absorption spectrometry was combined with pre-instrumental separation and enrichment techniques. Evaluation of the data from the programme made obvious significant geographical differences in the levels and the pattern with regard to the substances involved. For HCB, OCS and Hg a crucial point of contamination within the German Bright was recognized that was apparently influenced to a large extent by the inflow of waters from the Elbe.