The distribution of artificial radionuclides in the waters of the Norwegian-Greenland Sea in 1985

Abstract In the summer of 1985, sea water samples were taken to determine 3 H, 90 Sr, 134 Cs, 137 Cs and transuranics within a grid of 165 stations including 16 depth series down to the seafloor, covering all ice-free areas. The distribution of the activity concentrations and the nuclide ratios reveal the contamination pathway into the surface and deeper layers of the Norwegian-Greenland Sea from nuclear weapon fallout and civil nuclear technology. Moreover, the investigations show that: (1) a yearly discharge of 1 TBq (10 12 Bq) 90 Sr into the Irish Sea (English Channel) is diluted on its way to the southern Norwegian Sea, raising the concentration by about 0.04 mBq l −1 ; (2) the drift time to this sea area is around 4 years; (3) about 40% of the 137 Cs discharged does not reach the Norwegian Sea and (4) a further 30% leaves the Norwegian-Greenland Sea via the North Cape and flows into the Barents Sea. Investigations into the vertical distribution and stratification of the radioactivity indicate the time scale on which the radionuclides travel to the deeper layers.