SEASONAL-VARIATIONS IN CONCENTRATIONS AND RADIAL-DISTRIBUTION PATTERNS OF CD, PB AND ZN IN STEM WOOD OF BEECH TREES (FAGUS-SYLVATICA L)

Radial distribution patterns of Cd, Pb and Zn in stem wood of beech tr ees (Fagus sylvatica L.) in Germany were determined before, during and after the growing season. Element concentrations differed significant ly between the sampling dates. Concentrations of Cd and Pb were higher in December and April than during the growing season in June and Sept ember. Highest levels of Zn were found in April and lowest in Septembe r or December. Shifts in mineral composition of stem wood are discusse d in relation to physiological processes during the annual cycle of gr owth. Radial distributions of Cd showed increasing concentrations from the cambium towards the pith. Pb levels had a peak near the sapwood-h eartwood boundary. Highest Zn levels were found near the cambium and t he pith. The shapes and levels of these patterns were not stable durin g the annual growth cycle, i.e. they are not reliable sources of infor mation about former pollution levels.