Heavy metal distribution in a spruce ecosystem in the Solling mountains

In this investigation the distribution of Cr, Co, Cu, Zn, Cd and Pb was studied in a spruce forest. Heavy metal content was analysed in different compartments of the ecosystem. Inventory of these elements was calculated for tree layer, humus layer and upper soil. A decrease in meter concentration in wood from root to shoot showed strong immobilization of heavy metals in roots. Increasing content of Cu in wood of branches can be explained as storage of this micronutrient. Atmospherically deposited Cr, Cu and Pb were strongly adsorbed to organic substances and accumulate in bark, dead fine roots and humus layer. On the other hand Zn and Cd are more mobile in the ecosystem. High amounts of these elements were found in biomass. Accumulation in bark probably can be a strategy of the tree to store these elements in physiologically inactive forms. Increasing mobilization of Zn, Cd and Co in soil led to intensified root uptake and to higher seepage output. (orig.)