Heavy metal release from phosphorite tailings into seawater: a simulated laboratory study

A number of laboratory experiments were carried out to assess the desorptio n of trace metals from sedimentary phosphorite samples into artificial seaw ater. Shaking and percolation experiments have been performed on phosphorit e samples from the Cd-rich phosphorite deposits of Hahotoe-Kpogame (Togo, W est Africa) using artificial seawater in the ratio 1:10. The results show t hat elevated concentrations of trace elements Cd (17-256 mu g/l), Ni (12-19 3 mu g/l), Zn (21-200 mu g/l) and major elements Al (6-1915 mu g/l) and Fe (30-1264 mu g/l) are released into seawater by desorption processes. Maxima of trace metals with high mobility are reached within 4 h indicating the f ast desorption kinetics in seawater. Thus, the direct disposal of potential ly toxic metal-rich mine tailings may lead to regional coastal water pollut ion. (C) 1999 Elsevier Science B.V. All rights reserved.