Chemical Characterization and Bioavailability of Cadmium in Artificially and Naturally Contaminated Soils

Total concentration of cadmium in soil is often a poor indicator of cadmium availability to plants. In some Korean agricultural lands, cadmium concentration is steadily increasing due to the agricultural activities. But, it is still unknown whether this will lead to a concomitant increase of cadmium in plants grown on the soils. The objective of this research was to compare the cadmium availability of plants growing on the two contrasting soils with similar total cadmium concentration. The sequential extraction revealed that most of cadmium existed as immobile form (non-available fraction) in the naturally contaminated soil, while about 70% of cadmium existed as mobile form (available fraction) in the artificially contaminated soil. Spiking methods varying cadmium concentration, soil to solution ratio, and cadmium source had no effects on the 0.1 N HCl-extractable concentration of cadmium in soils. Aging of the spiked soils for 60 days also showed no difference in cadmium concentration in the artificially contaminated soil. To investigate the cadmium bioavailability by plant, Artemisia princeps var. orientalis was grown in the artificially and naturally contaminated soils and cadmium concentration was determined in the plant. Data showed that plant accumulated about five times higher concentrations of cadmium in the artificially contaminated soil as than that in the field contaminated soil as in the shoot. The overall result revealed that not the total concentration but the chemical form influenced the cadmium availability to plant.