Assessment of radiocaesium behaviour in an Austrian forest ecosystem

A monitoring program has been carried out since 1988 in Weinsberger Wald, an Austrian forest stand severely affected by the Chernobyl plume. Analyses of forest soils, understorey vegetation and mushrooms showed that 137Cs values decreased significantly between 1988 and 1993. In ferns, mosses and bilberry sprouts the concentrations did decrease to about 35% of the concentrations measured in 1988, however, seven years after the deposition event, the 137Cs contamination of edible forest products and game browse is still considerable. Derived ecological half-times are the longest in mushrooms (5.8 years), followed by values between 3.1-3.7 years in mosses, ferns and dwarf shrubs. Ecological half-times of 2.1 years were determined in grasses and the shortest values (1.9 years) were found in herbs (Oxalis acetosella). Annual measurements of 137Cs content in soil samples from different layers showed that the 137Cs values decreased in the litter layer, whereas they increased in mineral strata between 1988 and 1993. (author)