Change of Bioavailability in Heavy Metal Contaminated Soil by Chemical Amendment

Abstract

Crop safety in heavy metal contaminated agricultural field has been a critical issue in Korea and various remediation methods are proposed for minimizing heavy metal transfer from soil to crops. The main objective of this research was to evaluate remediation efficiency of two chemical amendments, lime and steel slag, and to decide extractant for assessing bioavailability of heavy metals. In order to select optimum extractant for evaluating bioavailability of heavy metals, four different single extractants, HCl, DTPA, CaCl2, NH4NO3, and sequential extraction method were examined. Both chemical amendments showed high immobilization effect for Cd (66%, 33.62 mg kg-1) and Pb (74%, 27.65 mg kg-1) in soil by HCl extractant. In terms of heavy metal concentration in rice grains, concentrations for Cd (77%, 0.023 mg kg-1) and Pb (82%, 0.039 mg kg-1) decreased, with addition of chemical amendments. HCl, DTPA, and sequential extractant showed the higher correlation between heavy metal concentration in soil and crops than others. These results indicated that they could be used for assessing bioavailability of heavy metals.