Over the last years, much attention has been paid to the radioactive contamination in the Norwegian marine environment. The fact that radioactive discharges from the British reprocessing plant Sellafield are transported with ocean currents to Norwegian waters, and that several potential sources in the Russian Arctic constitute a threat to our marine environment, has resulted in extensive monitoring programmes in Norway so as to document the radioactivity levels in our waters, fish and seafood.
This documentation has been important for the fish export industries as well as the Norwegian consumption of fish and seafood. Norwegian fish products are also being used as fish feed in fish farms. Fish feed used for this purpose is based on several different products and consists of approximately 60-70% of marine products, basically originating from fish such as capelin, herring, sandeel, Norwegian Pout etc. These fishes are hunted in the North Sea, the Norwegian Sea and the Barents Sea, among other sea areas.
Are the northern marine environments and fish contaminated by radioactivity or is it clean?
The most important sources that have contributed to the contamination of these waters are global fallout from atmospheric nuclear weapons tests conducted during the fifties and sixties, fallout from the Chernobyl nuclear accident (1986) and from Sellafield. It is important to stress that dilution as a result of mixing processes in huge amounts of water masses and radioactive decay has resulted in the fact that the levels in seawater, fish and seafood from these historic sources are in general low.
Recently published results (for samples collected in 1999) from the Norwegian national programme for monitoring Radioactivity in the Marine Environment can be summarised as follows: The concentration of caesium-137 (Cs-137) in surface water from the southern Barents Sea, ten different Norwegian fjords and in Kattegat, ranged from 3-23 Bq/m3 (maximum concentration in Kattegat).
The concentration of Cs-137 in fish species such as cod, polar cod, haddock, capelin, redfish, flatfishes, herring, mackerel etc. caught in the Barents Sea, the Norwegian Sea and 9 different Norwegian fjords was in general low, with a maximum concentration at a level of 1 Bq/kg (wet weight). The concentration of strontium-90 (Sr-90) in fish meat ranged from 9-25 mBg/kg (wet weight).
The concentration of Cs-137 in shrimps, crabs, lobsters and mussels was very low (or below the detection limit), with a maximum concentration at a level of 0.4 Bq/kg (wet weight).
Based on these results, and previously published data, the radioactive contamination of the northern marine environment is in generally low, this is also valid for the levels in fish and other seafood in general. This fact is clearly underlined when compared to the actual limits of Cs-137 for consumption as recommended by the EU and the Norwegian authorities, respectively: 600 Bq/kg for food articles (with the exception of milk and baby food which is 370) and 3000 Bq/kg for game, reindeer and wild, fresh water fish.
The fact that the present radioactive contamination, resulting from historic releases, is in general low, is made evident when compared to the high levels of Cs-137 which were exceeding 120 Bq/m3 in surface water of the North Sea in the late seventies.
Although the radioactive discharges from Sellafield has been reduced since the mid-seventies, when the discharges where high, the discharge of technesium-99 (Tc-99) has increased considerably since the mid-nineties. As a result of this, great opposition has been addressed to the British Nuclear Fuels Ltd. (BNFL, the owners of the Sellafield plant) and to the British authorities to stop the discharges into the sea.
This fact raises the question whether the enhanced discharges of Tc-99 from Sellafield have resulted in enhanced radioactivity levels in our marine environment.
Enhanced levels of Tc-99 were reported by the Norwegian national programme in surface water of the North Sea, the northern Norwegian Sea and the Barents Sea and this can be related to the enhanced discharges of this isotope from Sellafield. The concentrations ranged from 0.1 7 Bq/m3. The highest levels were observed in the North Sea.
Out of the numerous samples of crustacea and molluscs, Tc-99 was only detected in mussels and lobsters. The highest Tc-99 concentration was observed in lobster and ranged from 12-26 Bq/kg (wet weight).
Bellona has previously documented a maximum concentration at a level of 33 Bq/kg Tc-99 (wet weight) in lobster caught off the southern coast of Norway in 2001. Furthermore, in 1998, the Norwegian Radiation Protection Authority reported a maximum concentration of Tc-99 in lobster mounting to 42 Bq/kg (wet weight).
Another issue is the high levels of Tc-99 in seaweed, resulting from the increased discharges of this isotope from Sellafield over the last years. Up to 510 Bq/kg (dry weight) Tc-99 was observed in seaweed off the southern coast of Norway in 1999.
Although the Norwegian waters, fish and other seafood in general can be considered clean, the seaweed and lobsters can not. This clearly demonstrates the actual environmental problems caused by Sellafield, and there should be no doubt that this source must cease.
This fact is partly the result of much effort that has been made to reduce and stop the radioactive discharges from Sellafield and the extensive work to disclose and secure the potential sources of radioactive contamination in the Russian Arctic. Bellona has been working with these issues for more than ten years. Although the present radioactive contamination situation is in general low, the situation in the future will depend on how international authorities will handle these issues in the following.
- NRPA Bulletin, 2002. StrålevernInfo 2002:6. Norwegian Radiation Protection. Østerås, Norway, 2002.
- Radioactivity in the marine environment 1999. StrålevernRapport 2001:9. Norwegian Radiation Protection Authority and Institute of Marine Research. Østerås, Norway, 2001.
- Grøttheim S., 2000. Artificial radionuclides in the Northern European Marine Environment in 1995. Distribution of radiocaesium, plutonium and americium in sea water and sediments. StrålevernRapport 2000:1. Norwegian Radiation Protection Authority. Østerås, Norway, 2000.
- Brown J. et al., 1998. Technesium-99 contamination in the North Sea and in Norwegian coastal areas 1996 and 1997. StrålevernRapport 1998:3. Norwegian Radiation Protection Authority. Østerås, Norway, 1998.
- Kershaw and Baxter, 1995. The transfer of reprocessing wastes from north-west Europe to the Arctic. Deep-Sea Research II, Vol. 42, No.6, pp. 1413-1448, 1995. Elsevier Science Ltd.