MOBILIZATION OF PAH FROM POLLUTED SEABED AND UPTAKE IN THE BLUE MUSSEL (MYTILUS-EDULIS-L)

In several Norwegian fjords that have received effluents from smelters , there are significant accumulations of polycyclic aromatic hydrocarb ons (PAH) in the sediments; near the outfalls, concentrations may reac h several hundred mu g total PAH g(-1). As the smelters are now implem enting measures to clean up and reduce discharges, the accumulations f rom previous discharges could assume greater relative importance as a potential source. In order to give an assessment of the significance o f sedimentary PAH 'hot spots' in Norwegian smelter-affected fjords, an experiment was performed in which seabed sediment sections (0.5x0.5 m , 1.3 to 543 mu g total PAH g(-1)) were collected from the Oslo-, Saud a- and Sunndalsfjords and placed in an experimental set-up in which Os lofjord water taken from a depth of 40 m was passed over the sediment surfaces. The mobilization experiments indicated that a natural seabed containing 100 mu g PAH g(-1), and with a resuspension (due to biotur bation) within an expected natural range, might give an annual contrib ution to the overlying water of the order of 20 kg PAH km(-2). Mussels continuously exposed to the water from the test sediments accumulated PAH in a clear response to concentrations in sediments and water and to the degree of resuspension. PAH from the Saudafjord were apparently more bioavailable than those from the Sunndalsfjord, and it is argued that a more rapid accumulation in the former case was stimulated by a n elevated organic carbon content in the sediment.