Effects Of Different Modifiers On Plant Growth And Pb-Cd-Contaminated Soil

The differences in the activity of SOD and accumulation of MAD in plant max seeding, production of plants, metal adsorption, soil pH, morphology of soil metals etc were studied through pot culture experiment, which used yellow-brown earth from lion mountain in Wuhan, followed by adding different level of Cd, Pb solution into the soil, after 2 fortnight's equilibrium, adding lime, calcium magnesium phosphate, La, and citric acid respectively. The results show that:1 .The Cd, Pb contaminated soils decrease the production of cabbage and bean, and more production is decreased, as the concentration of heavy metal is higher. However, adding lime, calcium magnesium phosphate, La, and citric acid can increase the production significantly compared the comparison, while the effects of La and citric acid are better than the others'.2.The Cd, Pb contaminated soils increase the contents of Cd, Pb in the body of cabbages and bean, the more contaminant are, the more contents of them adsorbed by the plants. The contents of Cd, Pb is decreased significantly when lime, calcium magnesium phosphate, La, and citric acid are added respectively. The effect of lime on Cd, Pb contaminant soils that grow cabbages is the best, the effect of calcium magnesium phosphate on Cd contaminant soils that grow bean is also the best, and the effect of citric acid on Cd contaminant soils which grow bean is the best.3. The MDA content and the activity of SOD in the cabbage and bean are increased under Cd, Pb stress. Adding lime, calcium magnesium phosphate, La, and citric acid can decrease the MDA content and increase the activity of SOD in the body of plants. 4.The uptake of Cd, Pb by plant is increased significantly on Cd-Pb-Contaminated soils, while decreased significantly by adding the four modifiers. The uptake of Cd, Pb by roots is higher than that by leaves. This shows that the accumulation of Cd, Pb adsorbed by plants is mainly in roots, and the amounts of contaminants translated from roots to leaves are lower than that from soils to roots. The uptake of Cd is increased significantly higher than that of Pb; this shows that Cd is more available than Pb in the soil-plant system. 5.The content of Cd, Pb adsorbed by plants is related positively to the content of available Cd, Pb in soils, and the latter is influenced by the soil pH.