Ecological Effect of Combined Cd-Pb Pollution on Soil-tobacco System

A potted experiment was carried out to investigate the effects of combined pollution,migration and accumulation of heavy metals in soil-tobacco systems.The results showed that normal growth of tobacco in single element treatment and Cd-Pb treatment was seriously affected.The crop was 17.70 cm shorter in height and 38.44% less in yield than that in controlled trials.And there was significant decrease(p0.01).,The normal growth of tobacco in the five-heavy metals treatment was not affected clearly.In terms of distribution of Cd in the leaf of tobacco,the treatments were in the order: Cd-Pb treatment single element treatment.In terms of distribution of Pb in the leaf of tobacco,the order of the treatments was contrary to that of Cd.In the two elements treatment or the five elements treatment,the presence of Pb stimulated the plant to absorb Cd,but the presence of Cd inhibited the absorption of Pb by tobacco.Moreover,the elements of Cd and Pb tended to be accumulated in the aerial parts of tobacco,while Cd was more mobile than Pb to migrate upward.