INFLUENCE OF ORGANIC-ACIDS ON LEACHING OF HEAVY-METALS FROM CONTAMINATED MINE TAILINGS

Runoff and leachate from heavy-metal contaminated mining areas may be reduced through the establishment of vegetation; however, metal concentration in the leachate may increase as a result of acidification and complexation by organic acids generated in the rhizosphere by soil microorganisms and plant roots. In this research, the effects of formic, acetic, and succinic acids on the leaching of zinc from mine waste under saturated pulse flow and constant hydraulic head conditions were evaluated. Under saturated pulse conditions in moderately contaminated soil covered with mine tailings, leachate zinc concentrations decreased as the amendment acid concentration increased. Maintaining constant hydraulic head conditions, highly contaminated mine tailings were leached with neutralized solutions of formate and succinate. The zinc in the leachate of columns receiving 1000 mu mol/L of succinate was greater than in the leachate of columns receiving 0 and 250 mu mol/L concentrations.