This paper studies the influence of Cd~ 2+ at different
concentrations on the biological activities and the enzyme activities
in cole soil under laboratory conditions.The results show that the effects of different
concentrations of Cd~ 2+ on soil biochemical process are significantly different.The soil basal respiration and nitrification are promoted by Cd~ 2+ at lower concentrations while they are
inhibited at higher concentrations.What's more,the higher the concentration of cadmium is applied,the more significant the inhibition to observed activities.The soil polyphenol oxidase activity is mainly inhibited by Cd~ 2+,and the inhibition has no relation with the concentration of cadmium.The soil catalase activity is promoted by Cd~ 2+,and the promotion has no relation with the concentration of cadmium.The soil urease activity and the soil sucrase activity are promoted by Cd~ 2+ at lower concentrations,but they are inhibited at higher concentrations.The soil protease activity is promoted by Cd~ 2+ at very high or very low concentrations,while it is inhibited at appropriate concentrations.