草甘膦的土壤酶效应研究

Effect of Glyphosate on Soil Enzyme

为了探讨当今世界使用量最大的除草剂——草甘膦的土壤环境效应,本文采用室内模拟方法,较为系统地研究了我国4类土壤:褐土、黄绵土、风沙土和红壤,共11个土样中4种主要酶类(脲酶、转化酶、磷酸酶以及脱氢酶)活性与草甘膦间的关系,计算并得到了能够表征土壤轻度污染的生态剂量值ED10。结果表明:非缓冲液法较好地反映了土壤酶的实际情况;草甘膦总体上激活土壤脲酶、转化酶和脱氢酶活性,最大增幅分别为190%、1372%和42%;抑制磷酸酶活性,最大幅度为35%;磷酸酶与草甘膦间为完全抑制作用机理;激活脱氢酶活性揭示出草甘膦导致了土壤中微生物活性增强,从侧面反映出草甘膦是一种毒性较低的农药。计算获得4类供试土壤褐土、黄绵土、风沙土和红壤ED10值分别为168.3、438.5、35.1和141.4mg·kg-1;在一定程度上用土壤酶活性比生物来表征土壤污染程度更敏感。土壤性质对草甘膦的毒性有重要影响。

Glyphosate was one of the largest amount pesticides used in the world. It is an important scientific project to study its environmental toxicity. By simulation, the relationship between glyphosate and enzymatic activity（ such as urease, invertase, phosphatase and dehydrogenase ）in four tested soil types（cinnamon soil, loessal soil, sandy soil and red soil） was studied in this paper. And the ecological dose value （ED10） was calculated for assessing light contamination of soil. The results showed as follow, the non-buffer method was better to reflect real soil enzymatic activity than buffer method. Glyphosate activated the activities of urease,invertase and dehydrogenase as a whole and the most increasing rates were 190%, 1 372% and 42% respectively. While the activity of phosphatase in soil had been inhibited,and the drop rate was 35%. The reaction mechanism between phosphatase and glyphosate was fully inhibited. Glyphosate could strengthen the microbe activity because of activation of dehydrogenase, it was induced that glyphosate was a less toxicity pesticide. Ecological dose EDj0 of the four soil types were 168.3, 438.5, 35.1 and 141.4 mg·kg^-1, respectively. Soil enzymatic activity was more sensitive than that of biology to monitor soil polluted by glyphosate. Soil properties had a considerable influence on the toxicity of glyphosate.