Cadmium and lead immobilization in a calcareous contaminated soil using the cost-effective amendments

Abstract

The management of polluted soils is a major challenge for global environmental engineering. An incubation pot trial was conducted to assess the effectiveness of pumice (P), leca (LE), bentonite (BE), zeolite (Z), biochar 640 °C (BI1), and biochar 420 °C (BI2) as soil amendments to remediate a cadmium (Cd) and lead (Pb)-polluted soil. The DTPA- and EDTA-extractable Cd and Pb concentrations were measured to estimate the potential bioavailability of Cd and Pb in the calcareous soil. Additionally, Tessier’s fractionation procedure was used to determine various forms of Cd and Pb in non-amended and amended soils. Application of the amendments reduced the DTPA-extractable Cd by 51–68% and Pb by 12–32% compared with the control. The EDTA-extractable concentrations were decreased by 102–81 mg kg−1 (Cd) and 1202–792 mg kg−1 (Pb). All amendments decreased exchangeable fraction (F1) of Cd and Pb compared with the non-amended soil. Although the BI1 and BI2 exhibited the highest reducing rate of exchangeable fraction (F1) of Cd and Pb, respectively, they increased the oxide (F3) and organic (F4) fractions, which may be due to O-containing functional groups and high alkalinity leading to an enhance in the linking of Cd and Pb to organic compounds and mineral oxides.