Effect of single eleLent and coLpound pollution of Cd，Zn，Pb on soil catalase activity

Pot experiment was conducted to study effect of single cadium，zinc and lead as well as compound pollution of the tree elements on soil catalase activity in medium loam meadow cinnamon soil.The results show that single element zinc exhibits an obvious inhibiting effect on catalase and there is a significant linear negative correlation between them，whereas lead has an activating function on it，there is a significant linear positive correlation between them.When the concentration of cadium is less than 10mg／kg，cadium exhibits an activating function on catalase.When the concentration of the element reaches 50mg／kg，the activity of the enzyme is inhibited.The toxicity order of the inhibiting effect of the three elements on catalase is Zn>Cd>Pb.Under the combination of the three elements，influence of Cd，Zn，Pb compound pollution on catalase activity differs from that of each single element treatment.The characteristics of Cd and Zn exhibit a synergistic inhibiting negative effect，whereas Pb for catalase exhibits a protective effect，especially the high concentration of Pb.The catalase activity of compound pollution is more than that of single element Cd under the same Cd concentration.Zn is the same as Cd，but Pb is different from the front elements.The catalase activity of compound pollution is less than that of single element Pb under the same Pb concentration.