氧化乐果对土壤酶活性的影响

 【目的】氧化乐果是当今世界农业生产上施用的主要农药之一,为粮食增产提供了重要保障。但大量施用带来的环境污染、农产品品质降低等问题愈来愈受到人们的关注,因此开展其土壤生态毒理效应研究在理论和实践上具有重要意义。【方法】采用室内模拟方法,分析了不同氧化乐果污染浓度（0.0、0.5、1.0、5.0、10.0 g a.i.•kg-1）下,土壤中影响碳、氮、磷循环的三大水解酶（转化酶、脲酶和碱性磷酸酶）活性。【结果】氧化乐果可显著抑制土壤脲酶活性,关系达到显著或极著负相关;土壤脲酶活性可作为监测土壤污染程度的指标之一;模型U=A/(1+B×C)的较好拟合揭示出氧化乐果对土壤脲酶机理为完全抑制作用;从土壤脲酶角度计算获得土壤受氧化乐果轻微、中度和严重污染的临界含量分别为0.32、2.88和11.43 g a.i.•kg-1;而在供试氧化乐果浓度下,转化酶和碱性磷酸酶的最大变幅分别不超过18.61%和8.36%,揭示出转化酶和碱性磷酸酶对氧化乐果不敏感。【结论】在表征土壤氧化乐果的污染程度方面土壤脲酶最适;土壤酶与农药之间关系受到酶种类、农药品种、土壤性质等因素的影响。

Effect of Omethoate on Soil Enzyme Activities

Objective] Omethaoate is a major pesticide that is widely used in agricultural production in the world,and it has made an important contribution to grain production increase.Its negative influence of widely use on environment pouation has been concerned by peoples as the environment is worse and the quality of agricultural products are reduced.It is necessary and important to study soil ecological toxicity of pesticides in theory and application. Method ] By indoor simulation,soil enzyme activities,for example,soil invertase,urease and alkaline phosphatase,which catalyze carbon,nitrogen and phosphate nutrient cycling,were assayed in soil samples polluted by different omethaoate concentrations.Result] Omethaoate could remarkably inhibit soil urease activity,their relationship reached significant and remarkable significant correlation between soil urease activity and omethaoate conentration.Soil urease activity could be one of the indexes to monitor soil pollution by omethaoate.The model U=A/(1+B×C) was a better regression equation and it showed their reaction mechanism was a full inhibition between soil urease and omethaoate.The acquired critical concentrations were 0.32,2.88 and 11.43 g a.i.·kg~(-1) respectively with soils polluted slightly,medium and seriously by omethaoate.The maximum change was less than 18.61% and 8.36% for soil invertase and alkaline phosphatase activity respectively.Soil invertase and alkaline phosphatase were not sensitive to omethaoate.Conclusion]Soil urease is better than invertase and alkaline phosphatase to be one of indexs of soil polluted by omethaoate.The relationship between soil enzymes and pesticides is influenced by many factors such as enzyme types,pesticide variety and soil properties.