1 Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
2 Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), CH-8903 Birmensdorf, Switzerland
The elemental concentrations of K, Rb and Cs were determined in needles from individual spruce trees as a function of the needle age class. The concentrations are highest in current year´s needles and decrease smoothly in older needles, approaching a constant value. Rb and Cs show similar behaviour, whereas that of K differs in so far as its relative decrease with time is less pronounced. Intra- and intersite variation of the needle concentrations are largest for Cs and smallest for K. Individual trees show a highly significant correlation between the log (Cs) and log (Rb) values.
Total soil concentrations were determined at 9 sites with different parent material. Intra- and intersite variations of K are comparable for soils and for needles, whereas those for Rb and Cs are much smaller for soils than for needles. All three elements are correlated in soil samples.
There is no close connection between soil and needle concentrations at the various sites. However, the results suggest that needle concentrations of Rb and Cs, but not of K, are strongly dependent on the sorption properties of the associated soils.