二氰蒽醌在几种典型土壤中的降解吸附和移动特性

采用室内模拟试验方法,研究了二氰蒽醌在国内3种典型土壤江西红壤、东北黑土和太湖水稻土中的降解、吸附和移动特性。结果表明,25℃下二氰蒽醌在江西红壤、东北黑土与太湖水稻土中的降解半衰期分别为5.614、1.939、4.767d,其在土壤中化学稳定性较弱,易于降解,且pH越高,降解越快。二氰蒽醌在江西红壤的吸附等温线可以Freundlich方程很好地拟合,在东北黑土和太湖水稻土中的则可用线性方程拟合,吸附系数Kd值分别为36.4、114.6和51.9,Koc值分别为3 661.9、6 741.1、4 119.0,二氰蒽醌在土壤中具有中等或较强的吸附性能,在环境中迁移扩散的能力较弱。采用土壤薄层试验得到二氰蒽醌在这三种土壤中的移动分配系数Rf均<0.1,属于难于淋溶的农药,对地下水影响较小。二氰蒽醌在我国的几种典型土壤中均表现出了易降解性,难迁移以及难淋溶的特性,在目前的使用情况下,二氰蒽醌的环境风险较低。

Degradation,Sorption,Desorption and Leaching Migration of Dithianon on Three Typical Soils in China

Dithianon is often used as a fungicide in crop pretection and brings an increasing direct exposion to environmental matrix,which is now attracted more attention in environmental research field.In this study,degradation and leaching of dithianon in Jiangxi red soil,Northeast black soil and Taihu paddy soil,three typical soils in china,as well as sorption and desorption were investigated.The results of the laboratory experiments showed that the degradation half-lives of dithianon in Jiangxi red soil,Northeast black soil and Taihu paddy soil were 5.614d,1.939d and 4.767d,respectively.Dithianon shows a weak stability in soils and a more rapid degradation will occur with the increasing pH value of the soil.The sorption isotherms of dithianon on Jiangxi red soil was well fitted the Freundlich model,while that on Northeast black soil and Taihu paddy soil were obeyed the linear model,with the Kd values of 36.4、114.6 and 51.9 respectively,which suggested that dithianon in soil was difficult to mobilize,due to its middle or high soption ability.The caculated thin layer migration test Rf values of dithianon on the three soils were also not more than 0.1,consequently,under the common condition,application of dithianon would seldom conduce the leaching probability to underground water.Resultedly,the environment effects from the utility of dithianon was unlikely prone to be at any significant risk of contamination in soil.