Dynamic responses of soil enzymatic activities to oxytetracycline in soil

Effects of oxytetracycline (OTC) on soil enzymes including soil catalase, phosphatase, urease, sucrase, and dehydrogenase activities were studied under laboratory incubation conditions in the present paper. During the entire period of incubation, the activities of catalase, and phosphatase were significantly inhibited by OTC added. The inhibition of activities of soil sucrase and dehydrogenase by OTC was dependent on the retention time of OTC in soil. The activities of soil sucrase and dehydrogenase were slightly decreased until 56 days after OTC application (DAA), and were significantly decreased at 122 DAA. The adverse effect of OTC on soil urease was also noted. The activity of soil urease was siginificantly stimulated by OTC at the rate of 100 mg/kg added at 1 DAA, however, no significant effects of OTC on soil urease were observed during the remaining period of incubation time. Soil catalase and phosphatase were more sensitive to OTC in soil than other soil enzymes such as soil urease, sucrase, and dehydrogenase. Therefore, soil catalase and phosphatase can indicate soil contamination caused by OTC.