OCCURRENCE AND DISTRIBUTION OF POLYCHLORINATED DIBENZO-P-DIOXINS AND DIBENZOFURANS IN SEDIMENTS OF THE WESTERN BALTIC SEA

The occurrence and distribution of polychlorinated dibenzo-p-dioxins ( PCDDs) and dibenzofurans (PCDFs) were investigated in surface sediment s (0-2 cm) of the Belt Sea and Arkona Sea as well as of the internal a nd external coastal waters of north-eastern Germany (Mecklenburg-Vorpo mmern). The concentrations of different PCDD/PCDF congeners especially of the most toxic congeners such as 2,3,7,8,-TCDD were measured. The sum of PCDDs varied between 66,2 mu g/kg TOC and 2,1 mu g/kg TOC. The toxicity equivalents (TEQ according NATO/CCMS) ranged between 1,1 and 18,7. Elevated concentrations were observed in the surface sediments o f the internal coastal waters with highest concentrations in the Warno w estuary and in the Oder Haff. This indicates a significant contribut ion of river discharge to the contamination of sediments with PCDDs. E levated concentrations of PCDFs were observed in the Wismar Bight. The distribution of the individual PCDD/PCDF congeners in sediments vary widely depending on their structure and molecular weight. OCDD predomi nates in the western Baltic sea and in the internal coastal waters. (C ) 1997 Elsevier Science Ltd.