Mermoud A, Martins J M F, Zhang D, Favre A C
Inst. of Environmental Science and Technology, Swiss Federal Inst. of Technology, EPFL, ENAC, ISTE, HYDRAM, Station 2, 1015 Lausanne, Switzerland.
J Environ Qual. 2008 Aug 8;37(5):1929-36. doi: 10.2134/jeq2007.0298. Print 2008 Sep-Oct.
Soil sorption processes largely control the environmental fate of herbicides. Therefore, accuracy of sorption parameters is crucial for accurate prediction of herbicide mobility in agricultural soils. A combined experimental and statistical study was performed to investigate the small-scale spatial variability of sorption parameters for atrazine and dinoseb in soils and to establish the number of samples needed to provide a value of the distribution coefficient (K(d)) next to the mean, with a given precision. The study explored sorption properties of the two herbicides in subsurface samples collected from four pits distributed along a transect of an alluvial soil; two to four samples were taken at about 30 cm apart at each sampling location. When considering all the data, the distribution coefficients were found to be normally and log-normally distributed for atrazine and dinoseb, respectively; the CVs were relatively high (close to 50% for dinoseb and 40% for atrazine). When analyzed horizon by horizon, the data revealed distribution coefficients normally distributed for both herbicides, whatever the soil layer, with lower CVs. The K(d) values were shown to vary considerably between samples collected at very short distance (a few centimeters), suggesting that taking a single soil sample to determine sorption properties through batch experiments can lead to highly unrepresentative results and to poor sorption/mobility predictions.
土壤吸附过程在很大程度上控制着除草剂在环境中的归宿。因此，吸附参数的准确性对于准确预测除草剂在农业土壤中的迁移性至关重要。开展了一项结合实验与统计的研究，以调查土壤中莠去津和地乐酚吸附参数的小尺度空间变异性，并确定在给定精度下，为了获得分布系数（K(d)）均值附近的值所需的样本数量。该研究探讨了这两种除草剂在从沿冲积土样带分布的四个土坑采集的地下样本中的吸附特性；在每个采样位置，每隔约30厘米采集两到四个样本。考虑所有数据时，发现莠去津和地乐酚的分布系数分别呈正态分布和对数正态分布；变异系数相对较高（地乐酚接近50%，莠去津为40%）。按土层逐个分析时，数据显示无论土层如何，两种除草剂的分布系数均呈正态分布，变异系数较低。结果表明，在非常短的距离（几厘米）内采集的样本之间，K(d)值差异很大，这表明通过批量实验采集单个土壤样本以确定吸附特性可能会导致极不具代表性的结果以及对吸附/迁移性的预测不佳。
