LONG TERM STUDY OF 137Cs IN LICHENS AT DIFFERENT LOCATIONS IN AUSTRIA

S u m m a ry : Previous studies have demonstrated that lichens can accumulate high amounts of radioactivity. Because of their long life expectancy they are suitable and inexpensive biological detectors of the nuclear fallout. In this study, liehen samples were collected from diffe­ rent locations in Austria over a period of more than 15 years. Samples were taken before, immediately after and a few years after the nuclear accident of Chernobyl. As a result of the accident, all species showed a very high increase in the 137Cs activity concentration. Again, lichens appeared to be suitable detectors of local fallout pattems. The obtained data enabled us to estimate the biological half-life of 137Cs in the soil liehen species Cetraria cucullata, Cetraria islandica and Cladonia arbuscula. For the Alpine region in the Province of Salzburg, the biologi­ cal 137Cs half-life in Cetraria islandica is about 2 years; the other two species showed similar results, but with much higher uncertainty.