Matallo Marcus B, Spadotto Claudio A, Luchini Luiz C, Gomes Marco A F
Centro Experimental Central do Instituto Biológico, Campinas, São Paulo, Brazil.
J Environ Sci Health B. 2005;40(1):39-43. doi: 10.1081/pfc-200034208.
A study in small outdoor lysimeters was carried out to determine the leaching of the herbicides tebuthiuron and diuron in different soil types, using undisturbed soil columns. Soil sorption and degradation for both herbicides were also studied in the laboratory. The multi-layered AF (Attenuation Factor) model was evaluated for predicting the herbicides leaching in undisturbed soil columns. Tebuthiuron leached in greater amounts than diuron in both soils. Sorption was well represented by linear and Freundlich equations, however parameters from the linear equations were used in the AF model. In general, both herbicides presented very low sorption, with diuron presenting lower values of sorption coefficient than tebuthiuron in the two soils. Chromatographic data indicated rapid late degradation of diuron and tebuthiuron in both soil types at two different depths. Simple exponential equation was not able to represent degradation, thus a bi-exponential equation was used, and some model adjusting was needed. Average measured amounts of each herbicide were compared with amounts predicted by the multi-layered-soil AF model. The AF model was able to predict leaching amounts in the sandy soil, especially for diuron, however it did not perform well in the clayey soil.
利用原状土柱在小型户外蒸渗仪中开展了一项研究，以测定不同土壤类型中除草剂特丁硫脲和敌草隆的淋溶情况。同时在实验室中研究了这两种除草剂的土壤吸附和降解情况。对多层衰减因子（AF）模型进行了评估，以预测原状土柱中除草剂的淋溶情况。在两种土壤中，特丁硫脲的淋溶量均高于敌草隆。线性方程和弗伦德利希方程能很好地描述吸附情况，但在AF模型中使用的是线性方程的参数。总体而言，两种除草剂的吸附都非常低，在两种土壤中，敌草隆的吸附系数值均低于特丁硫脲。色谱数据表明，在两种不同深度的土壤类型中，敌草隆和特丁硫脲在后期均迅速降解。简单指数方程无法描述降解情况，因此使用了双指数方程，且需要进行一些模型调整。将每种除草剂的平均实测量与多层土壤AF模型预测的量进行了比较。AF模型能够预测砂质土壤中的淋溶量，尤其是对于敌草隆，但在黏质土壤中表现不佳。
