Occurrence, Sedimentation, and Spatial Variations of Organochlorine Contaminants in Settling Particulate Matter and Sediments in the Northern Part of the Baltic Sea

Abstract

Sediment trap sampling of settling particulate matter (SPM) was carried out in remote coastal and offshore stations in the Bothnian Bay (BB) and the Bothnian Sea (BS) located in the northern Baltic Sea. This was done to investigate occurrence, composition profiles, sedimentation, and spatial differences of PCBs, HCHs, hexachlorobenzene, DDTs, chlordane compounds, and dieldrin. The contamination load at the coastal stations was compared to that of surface bottom sediments. At one coastal station, sediment samples were collected in two different seasons (autumn and spring) in order to compare seasonal variations. All compound groups were found in the SPM and sediment samples analyzed. The contaminant concentrations in SPM at the coastal stations ranged, on dry weight basis, from 0.41 to 8.6 ng/g for chlordanes and HCHs and at the offshore stations from 3.2 to 31 ng/g for hexachlorobenzene and PCBs. The levels in SPM at the offshore stations were 10 times higher (on the average) than the coastal stations, li...