EDTA, Water-extractable Lead and Bioavailability of Lead in Soils/Tailings: The Effects of Zeolite and Beringite Amendment

Abstract

A study of the effects of varying rates of zeolite and beringite on water soluble Pb and EDTA-extractable Pb, pH and bioavailability of Pb in non-mined soil/tailings was undertaken. Water-extractable Pb, EDTA-extractable Pb were monitored for 0–12 weeks after amendment and bioavailability of Pb was evaluated by growing lettuce (Lactuca sativa) on amended soil/tailings for 4–12 weeks after incubation. Zeolite was more effective amendment in immobilizing Pb in soil/tailings. Application of zeolite led to decrease in the levels of water soluble Pb by 14–32%, 21– 44% and 32–51% in the non-mined soil, capped and uncapped tailings respectively at week 12. Similarly, EDTA-extractable Pb decreased by 14–33%, 11–19% and 41–48%. In non-mined soil, the application of zeolite resulted in lower concentration of Pb in lettuce (0.2 mg kg-1) while the capped tailings recorded higher Pb (0.33 mg kg-1) value than the FAO/WHO limit. The uncapped tailing recorded 0.67 mg kg-1 Pb.