Jan Magnusson

Modeling the fate of polychlorinated biphenyls in the inner Oslofjord, Norway.

A dynamic, segmented, multimedia fate and transport model has been developed, evaluated, and applied to gain insight regarding the behavior of seven polychlorinated biphenyl (PCB) congeners in the Inner Oslofjord (Norway). A comparison with a dated sediment core reveals that the model is not capable of reproducing some key features of the observed, historical, long-term trend in sediments, although better agreement is observed for six of seven PCB congeners over the last two decades. The model also underestimates the concentrations of PCBs in surface sediments in areas adjacent to the city of Oslo (Norway). In general, deviations between modeled and observed concentrations indicate that the historical emissions and discharges of PCBs are not sufficiently characterized and described. Net fluxes predicted by the model suggest that several congeners may have experienced a reversal of air-water and seawater-sediment exchange during the last decade or even earlier. The present study further suggests that the benefit of the proposed removal of the most contaminated sediments of the Inner Oslofjord needs to be assessed, with consideration of the relative contribution of current atmospheric inputs as well as the leaching of PCBs from less contaminated sediments.

Sea level oscillations with super-tidal frequency in a coastal embayment of western Norway

Abstract In a coastal embayment near the headland Stad in the northwest of Norway, recent measurements of sea water current and sea level revealed permanent barotropic oscillations with a mean period of 48 min. The sea level oscillations that are superimposed on the signal of the dominating semi-diurnal tide have a mean range of 3–5 cm, while maximum observed values exceed 20 cm. The character of the oscillation is different from numerously reported bay oscillations and seiches of comparable period, which are all transient. In this paper these observations are presented and analysed. Possible artifacts caused by sampling or analysis are investigated, and may be ruled out as an explanation. Due to its permanent character, the only possible energy source for the oscillations seems to be the regular semi-diurnal tide or one of its close constituents.