Differences in uptake and tolerance to heavy metals in Salix from unpolluted and polluted areas

Differences in tolerance to and accumulation of heavy metals between different Salix clones, grown on heavy metal polluted and unpolluted areas, were investigated. The concentrations of Cd, Cu and Zn in total and exchangeable fractions of the soils were 6-100 times higher in polluted than in unpolluted areas. Stems of different clones of 5 Salix species were collected and analysed for Cd, Cu and Zn, and investigated for tolerance and uptake properties. There were no differences between the unpolluted and the polluted areas, either in concentrations of Cd, Cu and Zn in the collected stems, or in the tolerance of Salix to the metals. Clones from the polluted area had higher accumulations of Cd, Cu and Zn in their roots and a lower transport of heavy metals to the shoots than clones from the unpolluted area. (C) 1996 Elsevier Science Ltd