I-129/I-127, I-129/Cs-137 and I-129/Tc-99 in the Norwegian coastal current from 1980 to 1998

Discharges of the nuclides I-129, Cs-137 and Tc-99 from the nuclear reprocessing facilities at Sellafield (UK) and La Hague (France) are very useful as oceanic tracers. On the basis of I-129/I-127, Cs-137 and Tc-99 measurements in archived seaweeds,the ratios of I-129/I-127, I-129/Cs-137 and I-129/Tc-99 have been estimated in seawater at two locations (Utsira and Kiberg) in the Norwegian Coastal Current from 1980 to 1998. These ratios, which vary up to two orders of magnitude over this period, are potentially very interesting for determining "transit times" in the Arctic and North Atlantic oceans. While the long-term trends in these ratios are quite clear, measurements in monthly and bimonthly samples show considerable structure. Further studies are required to determine the exact origin of this structure, which may be a limiting factor in the time resolution that can be obtained with these parameters.