Chemical fractionations and bioavailability of cadmium and zinc to cole (Brassica campestris L.)grow

A pot experiment was conducted to study the relationship between distribution of cadmium(Cd)and zinc(Zn)and their availability.to cole(Brassica campestris L.)grown in the multi-metal contaminated oasis soil in northwest of China.The results showed that Cd and Zn in the unpolluted oasis soil was mainly found in the residual fractionation,however,with increasing contents of Cd and Zn in the oasis soil,the distribution of Cd and Zn changed significantly.The growth of cole could be promoted by low Cd and Zn concentration,but significantly restrained by high concentrations.There was antagonistic effect among Cd and Zn in the multi-metals contaminated oasis soil.Stepwise regression analysis between fractionations distribution coefficients of the two meals in the soil and their contents in cole showed that both Cd and Zn in the exchangeable fractionation in the oasis soil made the most contribution on the uptake of Cd and Zn in cole.The bio-concentration factor(BCF)of Cd was greater than Zn in cole,and BCFs of the two metals in leaves were greater than those in roots.The translocation factors of the two metals in cole were greater than 1,and the two metals mainly accumulated in the edible parts in cole.Therefore,cole is not a suitable vegetable for the oasis soil because of the plants notable contamination by heavy metals.