Abstract: With pot culture and sequential extraction, this paper studied the effects of different added concentrations of cadmium (Cd) and lead (Pb) on the distribution of Cd and Pb forms in black soil and on the Cd and Pb uptake by cole plant. The results showed that with the increasing concentration of added Cd and Pb, there was a remarkable increase in the contents of exchangeable Cd and carbonate- and Fe-Mn oxide-bound Pb in soil. The exogenous Cd in soil was mainly existed in residual and exchangeable forms, while Pb was mainly in residual form but relatively low in exchangeable form. Lower concentration of added Cd and Pb had positive effects on cole growth, while their higher concentration inhibited the growth significantly. The concentrations of Cd and Pb were greater in root than in shoot, and less Pb was transferred to shoot, compared with Cd. The contents of all forms Cd and Pb in soil were positively correlated with those in cole shoot and root, but negatively correlated with cole dry mass. Among all the chemical forms of Cd and Pb, exchangeable form played an important role in the decrease of cole dry mass, and carbonate-bound form contributed most to the absorption of Cd and Pb by cole.

Key words: Soil organic carbon pool, Soil carbon density, Spatial distribution pattern, The Circum-Bohai Region