Comparison of Extractants for Prediction of Bioavailability of Cd in Soil to Green Onion in the Mining Affected Areas of Korea.

Bioaccumulation of Cd in crops from agricultural soils becomes major environmental and health concerns in Korea. This study was conducted to assess the prediction of Cd bioavailability in soil to green onion grown in the contaminated areas by evaluating metal extraction methods and Cd transfer factor to crops using statistical approach. Mean concentration of Cd in green onion was 0.422 mg/kg (0.048~3.245 mg/kg) indicating Cd levels exceeded the criteria set by FAO/WHO (0.06mg/kg) and EU (0.1mg/kg). The multiple stepwise regressions revealed that clay and 0.1N HCl extraction were major parameters for Cd translocation into green onion. The results supported that the current official method using 0.1N HCl extraction might still be a reasonable method to predict transfer factor for Cd in crops. Cluster analysis showed that among the extraction methods evaluated, the total contents of Cd in soil extracted by aqua regia were most suitable extractant for the prediction of the Cd availability to green onion in the contaminated soil.