Distribution and fate of polycyclic aromatic hydrocarbons (PAHs) in sediments and fluffy layer material from the Odra river estuary

The distribution and fate of polycyclic aromatic hydrocarbons (PAHs) were i nvestigated in surface sediments (0...2 cm) and fluffy layer material of th e internal and external coastal waters of the Odra river estuary (north-eas tern Germany). The area includes the Odra Lagoon (Oderhaff), the Greifswald er Bodden, the Pomeranian Eight, and the Arkona Basin. Elevated concentrations were observed in the surface sediments of the inter nal coastal waters with highest concentrations in the Odra Lagoon. This ind icates a significant contribution of river discharge to the contamination o f sediments with PAHs. During the exceptional Odra flood in the summer of 1 997 significantly higher concentrations of PAHs were-found in the fluffy la yer material of the Odra Estuary. The distribution of the individual PAH compounds varies widely depending on their structure and molecular weight. A concentration gradient of the lowe r molecular weight PAHs was found from the Odra Lagoon to. the open sea are as. The concentrations decreased rapidly fi-om the Oder Haff to the Arkona Basin. These results were found in both sediments and fluffy layer material . This is attributed to the degradation of the lower molecular weight PAHs during transport from the urban regions to the sedimentation basins. A decr ease of this magnitude was not found for the higher molecular weight PAHs ( i.e. benzo(a)pyrene) due to their higher persistence. An enrichment of thes e compounds was measured in the Arkona Basin.