pH对汞镉与土壤脲酶活性关系的影响

以土娄土为供试土壤 ,设置不同 p H及汞、镉浓度处理 ,研究 p H对汞镉与土壤脲酶活性关系的影响。结果表明 :在供试 p H范围内 ,脲酶活性在 p H5 .5～ 6 .0和 8.0～ 9.0时最大 ;汞镉加入几乎没有改变土壤脲酶最适p H;重金属生态毒性呈现 Hg>>Cd的规律性变化。统计分析表明 ,土壤脲酶活性、最大反应速度和反应速度常数均可在一定程度上表征土壤汞镉污染的程度 ;随重金属浓度增加 ,土壤脲酶 Km 基本不变 ,Vmax降低 ,表明土壤脲酶受汞镉作用机理主要为非竞争性抑制 ;在较宽 p H范围内 ,土壤严重污染的临界汞、镉浓度分别为 2 .0 98和 30 2 .83mg/ kg。

Effect of pH on relationship between soil urease activity and Hg,Cd

The relationship between Lou soil urease activity and Hg,Cd was tested under different pH.The result shows as followings:the optimum pH of soil urease is 5.5-6.0 and 8.0-9.0 among pH tested,and the optimal pH of soil urease would not change when soil was polluted by heavy metals,the order of ecological toxicity is Hg>>Cd,soil urease activity,reaction maximum velocity and reaction velocity constant can be indexes of pollutant by Hg and Hg+Cd,the reaction mechanism is mainly non competition inhibition because urease K m and V max is unvaried and decreased respectively.This paper also proposed the critical concentration of Hg and Cd is 2.098 and 302.83 mg/kg respectively under different pH tested.