A laboratory study on revegetation and metal uptake in native plant species from neutral mine tailings

Lygeum spartum, Zygophyllum fabago and Piptatherum miliaceum are typical plant species that grow in mine tailings in semiarid Mediterranean areas. The aim of this work was to investigate metal uptake of these species growing on neutral mine tailings under controlled conditions and their response to fertilizer additions. A neutral mine tailing (pH of soil solution of 7.1-7.2) with high total metal concentrations (9,100 and 5,200 mg kg(-1) Zn and Pb, respectively) from Southern Spain was used. Soluble Zn and Pb were low (0.5 and < 0.1 mg l(-1), respectively) but the major cations and anions reached relatively high levels (e.g. 2,600 and 1,400 mg l(-1) Cl and Na). Fertilization caused a significant increase of the plant weight for the three species and decreased metal accumulation with the exception of Cd. Roots accumulated much higher metal concentrations for the three plants than shoots, except Cd in L. spartum. Shoot concentrations for the three plants were 3-14 mg kg(-1) Cd, 150-300 mg kg(-1) Zn, 4-11 mg kg(-1) Cu, and 1-10 mg kg(-1) As, and 6-110 mg kg(-1) Pb. The results indicate that neutral pH mine tailings present a suitable substrate for establishment of these native plants species and fertilizer favors this establishment. Metal accumulation in plants is relatively low despite high total soil concentrations.