杀虫双对土壤脲酶活性特征的影响

通过模拟方法研究杀虫双对土壤脲酶活性特征参数的影响。结果表明 :不同生态区域土壤脲酶特征具有明显差异。杀虫双明显抑制脲酶活性 ,且随浓度增加 ,脲酶活性、酶促反应的Vmax、Vmax/Km、k减小 ,Km 增大 ,除 6号土样的Km 处理外均达到显著或极显著相关 ,揭示出脲酶特征参数可从不同角度表征杀虫双对土壤脲酶活性的影响 ,获得其作用机理为混合型抑制。脲酶活性ED50 值与土壤有机质、全氮和全磷呈现显著或极显著正相关关系 ,表明高有机质含量的土壤可明显减轻杀虫双的污染。

EFFECT OF DIMEHYPO ON SOIL UREASE ACTIVITY

The relationship between the concentration of dimehypo and soil urease activity parameters was studied in this paper. The results showed that the characteristics of soil urease had remarkable divergence among the tested soils from different ecological zones. Dimehypo inhibited soil urease activity very significantly and the characteristic parameters of soil urease, such as its activity, maximum reaction velocity V max, V max/ K m and velocity constant k excluding K m, were decreased with increasing dimehypo concentrations. The correlation of urease activity and dimehypo concentration was in very significant level with few exceptions. To a certain extent, urease activity can be used as an index to characterize the soil polluted by dimehypo. The enzymatic reaction mechanism was mixed-inhibitory between soil urease and dimehypo. It was concluded from ED 50 values that the high content of organic matter as well as total N and total P alleviated the ecological toxicity of dimehypo in soils.