Occurence and transport of organic micro-contaminants in sediments of the Odra river estuarine system

Over ninety surface sediment samples (0...3 cm) were collected in the Odra river estuarine system - from the Oderhaff, the Pomeranian Eight, the Peenestrom, the Greifswald Bodden - and the Arkona Basin between 1994 and 1996 and analysed for polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/F) and biphenyls (PCB), and p,p'-dichlorodiphenyl-trichloroethane (DDT) including their metabolites. The contents of all investigated organochlorines in the sediments of the western part of the Oderhaff (Kleines Haff) were only slightly higher and more homogenously distributed compared to the values of the Pomeranian Eight and the Greifswald Bodden. PCB contents (sum of 23 congeners) in surface sediments ranged between <130 and 9 550 pg/g (given for dry weight, dw). The results of individual PCB congeners showed that high contents of hexa- and heptachlorinated com-pounds (PCB 138, 153, 180) were present in the entire area investigated. Generally, low levels of PCDD/F were found in surface sediments of the Odra river estuarine system due to small industrial activities in the catchment area. Contents off PCDF (sum) and PCDD (sum) varied from 2.5 to 820 pg/g (dw) and from 13 to 2 991 pg/g (dw), respectively. The congener contents of PCDF showed a nonuniform picture between the Oderhaff and the Arkona Basin. In contrast, the congener profiles of PCDD showed approximately similar patterns at nearshore and offshore stations, with highest values of OCDD (octa CDD). We assume that most of the particulate-bound micro-contaminants (PCB, PCDD/F) are deposited in the eastern part of the Oderhaff(Stettin Lagoon), which acts as a temporary trap and 'purification' basin for the suspended particulate matter (SPM). One pathway for further transport of the particles seems to be the way on a small sedimentation strip along the island of Usedom via the 'Sassnitz-trough' into the deeper parts of the western Baltic Sea.