A soil and plant survey was carried out in a tailing heap afforested 30 years ago to gain information about the changes in the tailing and metal uptake by plants. A poor development of Technosol was found. It was observed accumulation of OM spatio temporarily. Metal concentrations in the soil profile varied between plots. Extractable Pb concentrations ranged from 0.4 to 2.9%; extractable Cd varied 9.7-46% of the total concentration. PCA analysis shows DTPA-Zn and DTPA-Cu, Na, K, and OM have the widest concentrations range between soil layers. Casuarina equisetifolia and Pennisetum clandestinum formed a pristine uniform litter layer, whereas Eucalyptus camaldulensis did not form a litter layer. Casuarina equisetifolia has a higher population density (756 p ha-1) compared to Populus nigra (528 p ha-1) and E. camaldulensis (621 p ha-1). Pennisetum clandestinum grew successfully and covered the tailing, but Cd and Pb concentrations were above the domestic animal toxicity limits, 0.5 and 10 mg kg-1, respectively. Populus nigra absorbed more Zn than Casuarina equisetifolia and Eucalyptus camaldulensis. Trees species did not accumulate high foliar Cu and Zn concentrations, but Pb (47.7-124.3 mg kg-1) and Cd (5.7-26.8 mg kg-1) concentrations are over those reported for mature leaf tissues. HighlightsPennisetum clandestinum formed soil cover on remediated plots.Casuarina equisetifolia was efficient in forming a litter soil horizon.Trasdescantia fluminensis accumulated Pb.Populus nigra accumulated Zn and Cd from the tailing heap.
Keywords: Mine residues; Technosols; phytoremediation; soil rehabilitation.