Transfer and Behaviour of super(137)Cs in Two Finnish Lakes and Their Catchments

The long-term behaviour of super(137)Cs in two freshwater ecosystems in southern Finland in an area most loaded by the Chernobyl fallout in 1986 was studied. Samples were taken from water, sediments, aquatic plants and fish in the lakes and from soil, mushrooms and seed plants in the catchment. In the Siikajarvi area, the values in the soil samples were very close to the deposition value, whereas in the Vehkajarvi area the total amounts in soil were much higher than the average deposition. The effect of humic substances on the uptake and delay of caesium in fish could not be proved. Perch and pike were more efficient accumulators of caesium than the best indicators among the aquatic plants.