铜对三叶草土壤酶系统的影响

通过盆栽实验研究了重金属Cu污染对植物（三叶草） 土壤酶（脲酶、蔗糖酶、过氧化氢酶和多酚氧化酶）系统的影响.结果表明,随着Cu浓度增加，脲酶、蔗糖酶、过氧化氢酶和多酚氧化酶活性均逐渐减小，与Cu浓度有高度相关性，蔗糖酶>多酚氧化酶>脲酶>过氧化氢酶.在处理浓度不变情况下，酶活性随时间而变化，且呈现低Cu浓度（<500 mg·kg^-1）时4种酶活性均有所上升，而Cu浓度增高（500～3 000 mg·kg^-1）时各酶活性逐渐下降的趋势.统计分析表明,在每一梯度浓度上,4种酶在Ⅰ、Ⅱ、Ⅲ组内均存在显著差异性(P<0.01),与植物受重金属Cu污染时的生长情况一致.随着Cu浓度增加，土壤pH值逐渐下降，而电导率上升；同一Cu浓度下的pH值和电导率均随时间呈缓慢上升趋势，统计分析显示,二者在Ⅰ、Ⅱ、Ⅲ组内均存在显著差异性(P<0.01).土壤pH值和电导率与4种土壤酶活性有高度相关性，多酚氧化酶>蔗糖酶>过氧化氢酶>脲酶.这4种酶同时可作为检测土壤环境质量的指标.

Effects of copper pollution on Trifolium repens growth and soil enzyme activities

The study with pot experiment showed that with increasing Cu concentration, soil urease, invertase, catalase and polyphenol oxidase activities decreased gradually. There was a significant correlation between Cu concentration and soil enzyme activities, with the correlated degree followed the order of invertase > polyphenol oxidase > urease > catalase. Under a fixed Cu concentration, soil enzyme activities changed with time, and the changes were different between high and low Cu concentrations, being increased slightly under low Cu concentration (< 500 mg x kg(-1)), but decreased gradually as Cu concentration increased (500-3000 mg x kg(-1)). Statistical analysis indicated that within the range of test Cu concentrations, the activities of test soil enzymes were significantly different among different Cu concentration (P < 0.01), which was accorded with the seedlings growth status. Soil pH was decreased, while electric conductivity was increased with increasing Cu concentration (500-3000 mg x kg(-1)), but they were increased with time under a fixed Cu concentration, with significant difference among different Cu concentration (P < 0.01) . Soil pH and electric conductivity were highly related to soil enzyme activities, with the order of polyphenol oxidase > invertase > catalase > urease. The test soil enzyme activities could be used as the indices of soil environment quality.