砂质壤土中农药阿特拉津阻滞因子的研究

采用批量平衡法和流动平衡法对农药阿特拉津在砂质壤土中的吸附特性进行了研究 ,获得表征其在水 土间分配的吸附常数 ,计算出阿特拉津在该质地土壤中运移的阻滞因子 ;同时 ,由易混合置换实验中测定的阿特拉津出流动态 ,通过求解对流 弥散方程的反问题 ,获得了砂质壤土对该农药的吸附特性参数 .此外 ,还利用阿特拉津的若干物化参数 ,求取了它的阻滞因子 .研究表明 ,实验方法与理论计算的结果具有较好的一致性

A study on retardation factor of atrazine in a sandy loamy soil

Adsorption is an important process of atrazine transport in soil. The objective of this study is to characterize the adsorption property of atrazine in sandy loamy soil from Changping Shahe. In this paper, adsorption isotherms were determined using the batch and flow equilibrium procedure. With the different values of linear distribution coefficient determined from laboratory experiments, we obtained the values of the retardation factor of atrazine in the soil. To verify the accuracy of the adsorption parameters, using the effluent data from a pulse-change input miscible displacement experiments, by solving inverse problems of the equilibrium and chemical nonequilibrium convection-dispersion equation with the computer code (CXTFIT 2.0), we estimated the optimized values of the retardation factor. It is shown that the conventional batch equilibration method gave superior precision to the flow equilibration method. On the other hand, we also estimated the organic carbon distribution coefficient of atrazine through its physical and chemical properties, i.e., the octanol-water partition coefficient, the melting point and aqueous solubility, and then calculated its distribution coefficient and retardation factor. These results indicate that the adsorption parameters calculated by our experimental data are in agreement with those estimated by the empirical formula.