Root versus canopy uptake of heavy metals by birch in an industrially polluted area: contrasting behaviour of nickel and copper

We investigated root versus canopy uptake of nickel and copper by mountain birch, Betula pubescens subsp. czerepanovi, close to a nickel-copper smelte r on the Kola Peninsula, northwest Russia. To distinguish between aerial co ntamination of leaf surfaces by dust particles and root-derived contaminati on of leaves by soluble metals, we transplanted seedlings from a control si te to clean and metal-contaminated soils and exposed these seedlings both i n clean and polluted sites. Patterns of leaf surface contamination and root uptake were similar for nickel and copper; however, nickel but not copper was effectively translocated from roots to shoots and leaves. The majority (80-95%) of nickel and copper found in birch foliage in the heavily contami nated site was due to deposition of dust particles on leaf surfaces, 32-40% of foliar nickel and 9-19% of foliar copper were in water soluble Forms. W ashing of fresh leaves removed only a minor part of surface contaminants; b oiling of unwashed leaves in distilled water for 15 min removed >90% of sol uble nickel and copper. (C) 2000 Elsevier Science Ltd. All rights reserved.