134Cs and 137Cs in lichen (Cladonia stellaris) in southern Finland

The variation of the amounts of fallout radionuclides in reindeer lichen Cladonia stellaris (syn. Cladonia alpestris) and the underlying soil below the lichen was investigated in 1986-2004 at three locations in southern Finland. Samples from the lichen carpet were fractionated into three vertical layers and the distribution of radionuclides between the different fractions was investigated. The effective half-lives of 137 Cs in lichen were almost the same in all three layers and, as a whole, the effective half-life of lichen varied from 2.7 to 3.4 years.