Effects of perchloroethylene soil pollution on soil enzyme activities

Simulated experiments were conducted to study the eco-toxicology effects of perchloroethylene (PCE) pollutant on three main soil enzyme activities: protease, urease and catalase. The results showed that, increasing the initial PCE concentration resulted in higher inhibition effect on both protease and urease activities. The process was inhibited firstly and then recovered. PCE had a significant inhibition effect on soil protease and urease activites when its concentration ≥0.15, and ≥3.0 mg/kg, respectively. The inhibition effect on soil protease and urease activites was indistinctive when PCE concentration <;0.05, and <;0.3 mg/kg, respectively. On the first day, the inhibitory rates for protease activity were 28.31%~63.64%, and reached the maximum levels. The inhibition term of PCE on protease was about 9~15 days. It had a high significant inhibition effect (49.7%~71.09%) to urease activity on the first day when PCE concentration was above 0.15 mg/kg. The inhibition term of PCE on urease was about 5-9 days. PCE had no obvious inhibition effect but a slight activation effect to catalase activity when its concentration was 0.05~30.0 mg/kg. Within the experimental concentration range, microbes in contaminated soil had great resistance to peroxidation. Soil protease and urease were the most sensitive to PCE. The different effects of PCE on different enzymes would affect the properties and functions of the PCE contaminated soil.