Effects of Increasing Dosages of Acid Mining Wastes in Metal Uptake by Lygeum spartum and Soil Metal Extractability

Mine tailings are an environmental problem in southern Spain because wind and water erosion of bare surfaces results in the dispersal of toxic metals over nearby urban or agricultural areas. Revegetation with tolerant native species may reduce this risk. We grew the grass Lygeum spartum under controlled conditions in pots containing a mine tailings mixed into nonpolluted soil to give treatments of 0%, 25%, 50%, 75%, and 100% mine tailings. We tested an acidic (pH 3) mine tailings which contained high concentrations of Cd, Cu, Pb, and Zn. Electrical conductivity and pH of the control soil were dramatically affected by the addition of the acid tailings (pH 2 dS m−1 in all treatments). Water extractable metal concentrations increased in proportion to the amount of tailings added (up to 1,000 mg kg−1 Zn). L. spartum survived, but only in the 25% treatment. In all treatments and for all metals, the plants accumulated higher concentrations in the roots than in shoots.