ACCUMULATION AND DISTRIBUTION OF PAH AND PCB IN DIFFERENT PARTICLE SIZE FRACTIONS OF CONTAMINATED MARINE SEDIMENTS Akkumulering og fordeling av PAH og PCB i ulike partikkelstørrelsesfraksjoner av forurensede marine sedimenter

The accumulation and distribution of PAH and PCB in different size fractions of contaminated sediments from The Norwegian Fjord Sandefjord and the bioaccumulation of these contaminants in sediment reworkers have been studied using dredged sediments. The sediment reworker Corophium volutator (a sediment reworker included in OSPAR’s toxicity test battery for chemicals used and discharged offshore in the North Sea) was used in the bioaccumulation study. Centrifugation was used for fractionating the sediment into suitable fractions prior to exposing the sediment reworkers in laboratory tests. The distribution of PAH and PCB in sediments and organisms was monitored. The results showed that centrifugation was a suitable technology for separation of the relatively fine sediment, which is typical for Norwegian Fjords, into different sizes fractions where the majority of the PAH could be recovered from the dry solids from the centrifuge while the PCB still was equally distributed in the different size fractions of the dry solids and the water fraction from the centrifuge. The measured bioaccumulation concentration of PAH and PCB in Corophium volutator feeding on the dry solid from the centrifuge was almost twice the concentration found in the water phase from the centrifuge. The results confirm that a proper prestudy is necessary to determine the effect of a physical pretreatment. The results also show that the effect on the bioavailability may differ from the effect on the contaminant concentration. Therefore, determination of the bioavailability of contaminants in sediments may add valuable information to physical and chemical analysis. The results did not give reason to conclude that neither the concentrate nor the centrate could be regarded as considerably less contaminated than the original sediment.