LONG TERM STUDY OF Cs-137 CONCENTRATIONS IN LICHENS AND MOSSES

Several studies carried out after the Chernobyl nuclear accident in 1986 showed that lichens and mosses are suitable bioindicators of the fall-out, given their long life expectancy. Cs-137 activities were measured in different mosses, epigeic and epiphytic lichens, collected from three sampling sites from Koppl, in the Salzburg province and the effective and biological half-time of Cs-137 were determined. The concentrations of Cs-137 ranged from 1765±13 to 7345±33 Bq kg dry weight in selected lichens (Cladonia fimbriata, Cladonia squamosa, Pseudevernia furfuracea, Hypogymnia physodes) and from 1145±16 to 14092±46 Bq kg dry weight in moss species (Leucobryum glaucum, Sphagnum papillosum, Dicranodontium denudatum, Polytrichum strictum, Sphagnum fallax). Earlier measurements on the same lichens and mosses species, sampled from the same spots by one of the authors (R.Türk), allow us to determine the biological half-time of Cs for these perennial plants. For the epiphytic lichen, Pseudevernia furfuracea, it was found a biological half-time of 12.9±0.9 years.