Comparison between the distribution of 137Cs and 40K in fir-tree (abies alba)

This study investigated and compared the distribution of 137Cs and 40K in different parts of the fir (Abies alba). Samples consisted of needles removed from branch sections of different age, of bark and of tree rings at the height of 8 m. Both isotopes showed a very similar behaviour. The behaviour of 137Cs was more regular than that of 40K. The activities of 137Cs and 40K were higher in needles grown on younger branches and were the highest in needles from the tips of the branches. The distribution of 137Cs and 40K was compared between needles and the bark as well as between tree rings and the bark. The ascending trend of both isotope activities in younger samples was observed for needles and the bark. A regular interdependence between 137Cs activity in needles and the bark was also observed. In all tree rings 137Cs activities were even and with small variations. Compared to the tree rings, the bark showed a great rise in 137Cs and 40K activities, which was more prominent for 137Cs than for 40K.(author)