Polycyclic aromatic hydrocarbons (PAHs) in sediments of the Baltic Sea and of the German coastal waters

Samples of surface sediments (0-2 cm) and sediment cores (0-45 cm, 1 cm slices) were collected in the Belt Sea and Arkona Sea as well as in the internal and external coastal waters of Vecklenburg-Vorpommern. The concentrations of PAHs were analysed by HPLC and fluorescence detection. The results were verified by GC/MS. The sum of PAHs varied between 11 ng/g dry weight for sandy sediments and 1900 ng/g for muddy sediments in the Belt Sea and Arkona Sea. Elevated concentrations up to 17000 ng/g 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 the significant contribution of river discharge to the contamination of sediments with PAHs, The distribution of the individual PAHs in sediments vary widely depending on their structure and molecular weight. The higher molecular 4 to 6 ring aromatics predominate due to their higher persistence. Vertical profiles of PAH-concentrations are characterised by a maximum at depth between 1 cm and 8 cm and by an almost constant background level at depth below 22-24 cm. These patterns may be explained by changes in the anthropogenic release of PAHs. The sedimentological properties also affect the accumulation of PAHs. Strong correlation's between concentrations of PAHs and the content of organic carbon could be established.