毒性金属Cd和Pb对土壤酶活性的胁迫效应研究

Assessment of Soil Enzyme Activity under Cd and Pb Stress

通过在土壤中添加外源重金属的室外盆栽试验,并运用相关分析和通径分析的方法,综合评价土壤基本化学性质及重金属Pb,Cd浓度对土壤酶活性的影响,取得如下一些研究结果:重金属Cd,Pb对土壤脲酶活性均表现出一定的抑制作用,脱氢酶对重金属的投加更为敏感,呈现显著的抑制作用。随着重金属浓度的提高,脲酶和脱氢酶活性总体上呈下降趋势,而酸性磷酸酶对重金属Pb,Cd的反应不敏感。因此用脱氢酶和脲酶活性来指示重金属Pb和Cd对土壤的污染是可行的。通径分析显示,土壤中Pb,Cd浓度、全磷含量与脲酶活性有较高的直接通径系数,直接作用是此3种因素影响脲酶活性的主要途径;土壤中Pb,Cd浓度对脱氢酶活性表现出强烈的直接作用,但被其反向间接作用减弱;土壤有机质含量和土壤全磷含量对酸性磷酸酶活性表现出较强的正向直接作用。

Based on the laboratory incubation and outdoor pot experiments of adding exogenous heavy metal in the soil,this study investigated the effect of lead and cadmium pollution on soil urease, dehydrogenase and acid phosphatase activities, Soil properties,content of heavy metals and soil enzyme activity were tested on the first 10 days, 22 days, 35 days.There was a certain inhibitory influence of single contamination of Pb,Cd on soil ur＇ease and dehydrogenase. The dehydrogenase was more sensitive to heavy metal pollution while the acid phosphatase showed no response with the adding of Pb and Cd. Stress of heavy metals on soil enzyme was most apparent in about ten days,and then stabilized after after thirty days. Urease and dehydrogenase was more sensitive to Cd than Pb. And urease activity showed some positive correlation with soil nitrogen content. Soil acid phosphatase activity positively responsed to the soil organic matter and soil total phosphorus content. Direct path coefficient reflecting the direct effects on soil enzyme and indirect path coefficients reflecting the activity variation with time of soil.