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 sediments (0-2 cm) of the Belt Sea and Arkona Sea as well as of the internal and external coastal waters of north-eastern Germany (Mecklenburg-Vorpommern). 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 μg/kg TOC and 2,1 μg/kg TOC. The toxicity equivalents (TEQ according NATO/CCMS) ranged between 1,1 and 18,7. Elevated concentrations were observed in the surface sediments of the internal coastal waters with highest concentrations in the Warnow estuary and in the Oder Haff. This indicates a significant contribution of river discharge to the contamination of sediments with PCDDs. Elevated 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 predominates in the western Baltic sea and in the internal coastal waters.