Abstract:
Pot experiment was conducted and Tessier′s five-step sequential extraction procedure was used to study the accumulation and migration of cadmium (Cd ) and zinc (Zn ) in the celery planted in the contaminated arid oasis soil in northwest of China. The results showed that Cd and Zn fractionations in the uncontaminated oasis soil existed almost in the residual fractionation, with Cd and Zn concentrations added increased Cd and Zn contents of the total amount and all fractionations also increased in the soil, moreover, Cd and Zn contents of the exchangeable fractionation (F1)and the carbonate-bound fractionation (F2) increased significantly, and those of the organic-bound fractionation (F3) increased slightly, those of the residual fractionation (F5) was almost unchanged; and with Cd and Zn concentrations added increased, the Cd and Zn contents of the carbonate-bound fractionation (F2) and the Fe-Mn oxide-bound fractionation (F3) gradually occupied the absolute superiority. With Cd and Zn concentrations added increased, Cd and Zn contents in celery roots and leaves increased correspondingly. And doing correlation analysis found that there was significant correlation between the content of the organic-bound fractionation Cd in the soil and Cd contents in the leaves and the roots, which showed that the organic-bound fractionation Cd had the greatest contribution to Cd on the accumulation in the celery leaves and roots. Similarly, there was significant correlation between the contents of the organic-bound fractionation Zn and the carbonate-bound fractionation Zn in the soil and the contents in the celery roots and leaves, respectively, which suggested that the organic-bound fractionation Zn and the carbonate-bound fractionation Zn had the greatest contribution to Zn on the accumulation in celery roots and leaves, respectively. The Bio-concentration Factors (BCF) in the celery leaves and roots were all greater than 1, moreover the BCF of Cd was greater than Zn, and, the BCF of the two metals in the roots were greater than leaves, which showed that uptake capacity to Cd was greater than Zn for the celery, and the toxicity of Cd is also greater than the corresponding Zn for the celery. However, the bio-translocation factors (BTF) of the two metals were all lower than 1, indicating that the migration capacity of Cd and Zn in the celery was weaker, and the two metals in the edible leaves of the celery had less accumulation.
