苯噻草胺在土壤中的吸附与解吸行为研究

Sorption and Desorption Behavior of the Herbicide Mefenacet on Soils

采用批量平衡实验方法,研究了除草剂苯噻草胺在5种不同性质土壤中的吸附与解吸行为,并探讨了土壤有机质及溶液pH值对吸附的影响.结果表明,线性方程与Freundlich方程均能较好地拟合苯噻草胺在土壤中的吸附等温线.计算得到苯噻草胺在5种土壤中的碳标化分配系数Koc在849.5-1 818.8 L·kg^-1之间,说明土壤对苯噻草胺有较强的吸附能力.苯噻草胺在土壤中的分配系数KdF、reundlich常数Kf以及Kf（1/n）与土壤有机质含量均呈显著正相关.通过过氧化氢去除有机质后,土壤对苯噻草胺的吸附大大降低,说明土壤有机质是影响苯噻草胺在土壤中吸附的主要因素.对于同种土壤而言,苯噻草胺的吸附量随pH值的增大而减小.解吸实验表明,苯噻草胺在土壤中的解吸过程具有一定的滞后性,推测其在土壤中的迁移能力较差.

The sorption-desorption experiments of the herbicide mefenacet on five soils with different physieochemieal properties were conducted using bath equilibrium methods, and the effects of soil organic matter and pH value on sorption of this herbicide were also investigated. The results showed that the sorption and desorption behaviors of mefenacet on soils could be well described by beth the linear model and Freundlieh model. Sorption distribution coefficients Koo for five tested soil are between 849.5 L·kg^-1 and 1 818.8 L·kg^-1, which shows that mefenaeet can be well adsorbed on soils. It is found that the sorption coefficients, Kd, Kf, and Kt（1/n） had good correlation with organic matter content （OM） in soils. It is obviously suggested that organic matter was the dominant factor affecting the sorption of mefenaeet on soils. For the same soil, the sorption amount of mefenacet decreased with the increase of pH value. The desorption hysteresis of mefenacet was revealed in the single-cycle sorption and desorption experiments, which indicated a weak transferability of this herbicide in soils.