To study the relations between soil enzyme activities and heavy metal pollution, the combined effects of Cu, Zn and Pb on the three hydrolase activities, including invertase(IN), urease(U)and alkaline phosphatase(ALP)were investigated via an orthogonal experiment. Results showed as the following:When the concentration of Cu was 400 mg·kg-1, the U and ALP activities were decreased 51%and 44%, separately;When Zn was at 500 mg·kg-1, IN and ALP activities were only decreased 3%and 9%, while U activity was increased;When Pb was at 500 mg·kg-1, IN and U activities were increased, while ALP activity was decreased 13%. As a whole, Cu was considered as the most remarkable influence factor for IN, U and ALP activity regardless of interactions among the heavy metals, Zn came second, and Pb mainly showed activation. Considering interactions, Cu×Zn could significantly influence U activity(P﹤0.05), effects of Cu×Pb and Cu×Zn on ALP activity were remarkable(95%confidence interval). The response of ALP activity was more sensitive than the other two enzymes. Soil ALP activity might be a sensitive tool for assessing the pollution degree of Cu.%为研究土壤酶活性变化和重金属污染的关系，通过室内正交实验，考察重金属Cu、Zn和Pb复合污染对转化酶、脲酶和碱性磷酸酶3种水解酶活性的影响。结果发现：Cu浓度为400 mg·kg-1时，脲酶和碱性磷酸酶活性分别是对照样品的49%和56%；Zn为500 mg·kg-1时，与对照样品酶活性相比，转化酶和碱性磷酸酶活性分别是对照样品的97%和91%，脲酶活性有所增加；Pb为500 mg·kg-1时，转化酶和脲酶活性比对照升高，碱性磷酸酶活性降低，是对照样品酶活性的87%。Cu对3种酶都有抑制作用，效果最显著，Zn次之，Pb主要体现为激活效应；考虑交互作用时，Cu×Zn对脲酶活性有显著影响（P﹤0.05），在95%置信区间下，Cu×Zn、Cu×Pb对碱性磷酸酶酶活性影响显著；3种水解酶中以碱性磷酸酶活性对重金属的影响反应最敏感，表明碱性磷酸酶活性可以表征土壤重金属Cu的污染程度。
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