Simulating the Fate of Polycyclic Aromatic Hydrocarbons (PAHs) in the Sunndalsfjord

Abstract

As part of the ongoing discussion on remedial actions against PAH contaminated sediments in the Sunndalsfjord, the SedFlex-Tool was applied to the Sunndalsfjord system in order to investigate the magnitude PAH transport from the inner Sunndalsfjord (i.e. near Sunndalsøra) to outer fjord areas (e.g. the Tingvollfjord), concentrations of PAHs in blue mussels in the Tingvollfjord if future emissions from the Sunndal plant are assumed to be zero, and how the concentrations of PAHs in the sediments in the Sunndalsfjord and Tingvollfjord will change with time. Maine conclusions are: - The transport of PAHs from the inner Sunndalsfjord to outer fjord areas in 2000 was initially estimated to be approximately 1000 kg year-1, dominated by the flux from the contaminated sediments. - The total PAH and Benzo[a]Pyrene concentrations in blue mussels inhabiting the surface layer (0 – 5 m) in the Tingvollfjord will fall rapidly once direct emissions to the system cease. The model also demonstrated that inputs from background atmospheric and riverine sources control the long-term levels of PAHs in blue mussels, rather than remobilization of contaminants from the sediments The initial total PAH levels in sediments (surface, intermediate and deep) in the Sunndalsfjord and Tingvollfjord were estimated to be approximately 11 720 µg kg-1 and 1035 µg kg-1 respectively. The model indicated that these levels decline relatively quickly and reach levels approximately 2-3 orders of magnitude lower over the simulation period