BASE-LINE CONCENTRATIONS OF COPPER AND ZINC IN SHOOT TISSUES OF A RANGE OF SALIX SPECIES

Background concentrations of Cu and Zn in bark, leaves, twigs and wood of eight species of Salix (willow) growing on the same soil type were investigated. It was found that the concentrations of Cu and Zn varie d between plant parts and between species. There was no consistent pat tern of metal concentration. Copper concentrations decreased in the or der twigs > leaves > wood, bark, and those of Zn in the order Leaves > bark > twigs > wood. The eight species did not show a common uptake p attern for the two metals. S. x sericans and S. cinerea had high conce ntrations of both metals; S. purpurea had high concentrations of Zn bu t low concentrations of Cu, whilst S. fragilis and S. viminalis had lo w concentrations of both metals. Concentration factors for both elemen ts in shoot tissues were consistent, despite the variations in associa ted metal concentrations. A general trend of exclusion of Cu and conce ntration of Zn was evident. More Cu than Zn was fixed in woody tissue. (C) 1997 Elsevier Science Ltd.