Deposits from historic events in the Aurlandsfjord, Western Norway, over the last 40 years : the pollution record

Abstract

Flåm at the Aurlandsfjord, Western Norway, is a popular destination for cruise tourism. The main attraction of Flåm is the Flåmbane, a railroad that runs between Flåm and Myrdal. The railroad attracted 920.000 tourists in 2016 and 171 cruise ships will arrive at Flåm in 2017. The prediction is that The growth of the cruise ship industry increases the risk of pollution in the Aurlandsfjord. To investigate this, sediments cores were taken and investigated from three marine basins near Flåm. These basins are the Cruise Ship Harbor at 37 m, the Kistadypet at 64 m, and at Stampa at 60 m water depth. The assumption was made that an increased amount of cruise ships would have led to an increased amount of sediment pollution. The sediments were dated using sediment signals of local building activity (completion of the cruise ship quay in 1985) and the century flood of 2014, resulting in a linear sedimentation rate from 0,27 to 0,75 cm/year. Samples from the sediment surface and from about 10 cm sediment depth were compared regarding the contents of PAHs, PCBs, TBT, Cu, Cr, Ni, Zn, Hg, Cd, Pb and As. The results showed that the sediments in the Cruise Ship Harbor were polluted with up to 5,6 μg/kg TBT, falling in Class V ‘Heavily Polluted’ of the Norwegian Environmental Directorate sediment classification of 2016. No TBT was detected in the Kistadypet and at Stampa. All other contaminants in the sediments of the Cruise Ship Harbor, the Kistadypet and at Stampa fell in Class II ‘Good’. No major changes were detected between the surface subsample and the 10 cm subsample at either station and the sedimentation rates increased by a factor of 2,78. The use of TBT has been completely prohibited since 2008 and terms of site management, this indicates that action against TBT pollution should be taken in the Flåm Cruise Ship Harbor. Further studies need to be done on the TBT to gathering more information and monitoring the conditions of TBT in the Aurlandsfjord.