Effects of the combined pollution of Pb2+ and Cd2+ on soil urease activity were shown in Table 2.
Compare with the controls, the enzymes activities were decreased with the increasing concentrations of
Cd2+ and the incubation periods except for treatments of 0.5 mg/kg Cd2+ only and 0.5 mg/kg Pb2+ and 0.5
mg/kg Cd2+ combined. Urease activities were found to be sensitive to the inhibition effect of heavy metals.
After 45 days incubation under the concentrations of 100.0 mg/kg Pb2+ and 0.5 mg/kg Cd2+ combined, the
inhibition rates of soil urease activity was determined at 73.1 % compared to the control.