单一及复合重金属污染对土壤酶活性的影响

采用外源添加重金属和室内培养的方法研究重金属Cd、Pb对滩涂盐渍土脲酶、过氧化氢酶活性的影响,为中国沿海地区土壤重金属污染的监测及重金属对潜在生态环境影响等方面的研究提供参考依据。重金属Cd添加至土壤的质量分数为0、0.5、1.0、2.0 mg.kg-1,重金属Pb添加至土壤的质量分数为0、100、200、400 mg.kg-1,采用完全随机区组设计,3次重复。结果表明：重金属质量分数较低时,单一重金属对土壤脲酶活性具有促进,对过氧化氢酶活性具有抑制作用;重金属质量分数较高时,对土壤脲酶活性具有抑制作用,对土壤过氧化氢酶具有促进作用。重金属Cd、Pb对土壤酶活性的影响存在交互作用,重金属Cd对土壤脲酶活的性影响起主导作用,重金属Pb对土壤过氧化氢酶活性的影响起主导作用。经逐步回归分析,有效态重金属的质量分数低水平时,土壤脲酶活性与重金属Cd呈现显著负相关;土壤过氧化氢酶活性与重金属Pb呈现显著正相关。

Influence of single and combined pollutions of heavy metal on soil enzyme activity

The influences of Cd,Pb addition on urease and catalase activities in reclaimed tidal flat soils were studied by indoor incubation,which supplied references for monitoring of potential heavy metal contamination and eco-environment in coastal region.The experiment was performed by completed randomized bloc design using three replications,consisting of 4 added doses for Cd（0,0.5,1.0,2.0 mg.kg-1） and 4 added doses for Pb（0,100,200,400 mg.kg-1）,respectively.The results from the experiment indicated that the urease activity was promoted by single heavy metal at low concentration,but the catalase activity was restrained;at higher concentration,the urease activity was restrained by single heavy metal,but the catalase activity was promoted.There were significantly interactions for soil enzyme activities between Cd and Pb,and the dominant factor was Cd for urease activity and was Pb for catalase activity.Using stepwise regression analysis,at low available heavy metal concentration,the urease activity was negatively related to Cd concentration,but catalase activity was positively related to Pb concentration at P≤0.05 level.