Simulated Bioavailability of Heavy Metals (Cd, Cr, Cu, Pb, Zn) in Contaminated Soil Amended with Natural Zeolite Using Diffusive Gradients in Thin-Films (DGT) Technique

The aim of this study was to investigate the effect of natural zeolite amendment to contaminated soil on the heavy metal (Cd, Cr, Cu, Pb and Zn) simulated bioavailability over a three-month period of storage. Two pot experiments were created by amending soil with two different amounts of natural zeolite (3 and 6 wt.%). During the experiment, pH level, metal concentrations in soil solution (C-sol) and metal concentrations in soil by the diffusive gradients in thin-films technique (C-DGT) were determined. When the zeolite was added to the soil, a significant decrease (p = 95%, n = 3) for Cd and Pb concentrations, both in C(sol )and in C-DGT, was observed. The Cu, Cr and Zn concentrations also showed a decreasing trend, but the changes in their concentrations were not statistically significant. The R ratio between C-DGT and C(sol )was calculated for each metal in order to assess the resupply of metals from the soil solid phase to soil solution. The R values significantly decreased for Cd and Pb, showing a low resupply from the solid phase in the samples with added zeolite.