Radioactivity in seafood and sea plants

Radioactive caesium, strontium and technetium concentrations are continuously measured in samples of seaplants and seafood from Danish seas. The uptake of radiocaesium in seaweed is proportional to temperature and inversely proportional to the water salinity, which gives a seasonal variation with a maximum in the summer period, when the ice has melted. Seaweed concentrations of ¹³⁷Cs seem to generally decline with an effective half-life of 10-15 years, whereas the decline in ¹³⁴Cs concentrations is governed by the physical decay of this radionuclide (half-life of 2.06 years). The main source of ¹³⁷Cs in Danish seaplants and seafood after the Chernobyl accident has been the Baltic sea. Thus, fish from the Baltic sea have been measured to have 3-4 times higher levels of ¹³⁷Cs than those from inner Danish waters. In contrast, ⁹⁹Tc concentrations are highest in the waters nearest to the nuclear fuel reprocessing plants in Sellafield, UK, and Cap de la Hague, France.

	Caesium-137 in seaweed (Fucus vesiculosus and Fucus seratus) from February 1983 to June 2009 collected at Klint, Zealand (55°58’N, 11°35’E).
	Caesium-137 in flatfish from the sea near Zealand (Hundested) and Bornholm from 1968-2009
	Caesium-137 in herrings from the sea near Zealand (Hundested) and Bornholm from 1966-2009
	Caesium-137 in codfish from the sea near Zealand (Hundested) and Bornholm from 1966-2009

Page updated by 25.08.2009

Kasper Grann Andersson
Senior Scientist
Radiation Research (NUK)
Dir tel+45 46774173