Effects of carbon tetrachloride contamination on enzyme activities in soil

Using the method of stimulation experiment, the effects of carbon tetrachloride (CT) concentrations on the three main enzyme activities in the soil: protease, urease, catalase were studied. Copper salts assay, Nessler's reagent spectrophotometer method and potassium permanganate titrimetric method were taken to detect the activities of protease, urease and catalase. The results show that increasing initial concentration resulted in higher inhibition to protease activity and urease activity. The process was inhibited firstly and then recovered. The protease activity was more obviously inhibited by CT of 3.2 × 10-6 but wasn't inhibited by CT of 1.6 × 10-6, this inhibition was 7.90%-38.86% first day and the inhibition term was about 5 days; Above 1.6 × 10-6 of CT had highly significant inhibition (51%-72%) to urease activity first day, the inhibition term was about 1 day. CT of 1.6 × 10-6 - 16.0 × 10-5 hasn't obvious inhibition to catalase activity and even had a little activation. It showed that catalase had great capacity from peroxidation. Soil urease was the most sensitive to CT. The different effects of different enzyme could affect the properties and function of the CT contamination soil.