Effects of Cu, Zn, Cd and EDTA on Soil Enzyme Activities

Enzymatic activities in heavy metal polluted soil had been widely used to indicate the extent of pollution.In a pot experiment, the effects of Cd, Zn, and Cu on soil enzyme activities in rhizosphere and non-rhizosphere soils, and the effect of EDTA, as a soil amendment, on the heavy metal contaminated soils were studied. the activities of urease, alk-phosphatase, and inverstase activities in soils contaminanted by Cu, Zn, and Cd were measured. Wheat was used as the study crop and planted in the plastic pot. Root bags made of 300 mu nylon cloth were used to divide rhizosphere and non-rhizosphere soils. The results showed that soil enzyme activities were higher in the rhizosphere than that in the non-rhizosphere soil. In addition, compared with the untreated control, the contamination of Cu, Zn and Cd reduced soil enzyme activities, both in the rhizosphere and in the non-rhizosphere soil. After adding EDTA to these soils, the only inhibition of soil enzyme activities by Zn was significantly alleviated (P0.05). In conclusion, we can use soil urease?alk-phosphotase and invertase activities as indexes to indicate the degree of soil contamination by Cu, Zn and Cd.