毒死蜱在农田土壤中的迁移能力研究

Migration Ability of Chlorpyrifos in Different Agricultural Soil Profiles

【目的】掌握不同深度剖面土壤对毒死蜱的吸附特征以及土壤理化性质与毒死蜱吸附程度的关系,全面准确地评价毒死蜱在土壤中的迁移能力及其对地下水污染风险。【方法】采用批量吸附实验考察南北方3个不同农业区(常州、天津和寿光)不同深度剖面土壤对毒死蜱的吸附特征,并使用Linear模型、Freundlich模型对吸附动力学与吸附等温数据进行拟合,同时采用Spss 13.0软件分析土壤对毒死蜱的吸附能力与土壤理化性质的相关性。【结果】土壤对毒死蜱的吸附符合二级动力学吸附规律(R^2=0.95~0.99),常州表层土壤对毒死蜱的吸附速率最低。Freundlich方程能较好地对土壤吸附毒死蜱的动力学进行拟合(R^2=0.93~0.99),3个研究区表层土壤对毒死蜱容量均明显高于下层土壤。毒死蜱对3个研究区地下水的污染风险为常州>寿光>天津。土壤对毒死蜱的吸附能力主要与有机质含量有关,其次是矿物含量。【结论】土壤对毒死蜱的吸附是一种快吸附慢平衡过程;研究所得的线性回归方程能被用于估算风险评价中的相关指标值,可为毒死蜱污染地下水风险评价中相关指标值的获得提供简单可行的方法。

【Objective】This study was aimed to analyze the migration ability of chlorpyrifos in different kinds of agricultural soil profiles,as well as the corresponding pollution risk of groundwater.【Methods】The sorption characteristics of chlorpyrifos in different depth of soils from the north and south agricultural regions,including Changzhou,Shouguang,and Tianjin cities,were investigated using the batch sorption test.The adsorption kinetic and isotherm data were fitted by Linear and Freundlich models.The correlation between chlorpyrifos adsorption ability and physicochemical properties of soils was analyzed using the Spss 13.0software.【Results】Chlorpyrifos sorption by soils with different depth can be described by the pseudo-secondorder（R^2=0.95 ~ 0.99）kinetics equation,and the topsoil of Changzhou exhibited lowest sorption rate towards chlorpyrifos.The sorption process can be well described by the Freundlich model（R^2=0.93~0.99）.All of the topsoil in the three agricultural regions exhibited high-er sorption capacity for chlorpyrifos than that of the subsoil.The groundwater pollution risk of chlorpyrifos was estimated as follows：Changzhou〉Shouguang〉Tianjin.The results of correlation analysis showed that soil sorption capacity of chlorpyrifos was mainly depended by the content of soil organic matter and then the minerals.【Conclusion】The adsorption behavior ofchlorpyrifos to soils with depth can be described by two stages：Initial rapid adsorption and slow equilibrium process.The linear regression equation obtained by correlation analysis can be used to calculate the parameters such as Kf,nand Koc,which provides a simple and feasible method for obtaining values of indexes in groundwater pollution risk assessment.