A field injection experiment was performed in an anoxic sandy aquifer over 6 days to assess sorption characteristics of 7 commonly applied pesticides in agriculture and 2 frequently detected metabolites. Pesticide use changed considerably in the last decades, and there is insufficient knowledge of the fate of currently used pesticides in aquifers. Injected water arrival was monitored at 6 depth intervals of 1 m ranging from 11.4 to 32.2 m-below surface level with varying organic carbon contents (0.057–0.91%d.w.) to examine intra-aquifer variations in sorption. Observed pesticide concentrations were fit using a non-linear least squares routine to an advection-dispersion equation, from which retardation factors (R) were obtained. Pesticide degradation did not significantly influence the simulated R during the experiment. We observed that bentazon and cycloxydim were most mobile with R < 1.1 at all depths. Desphenyl chloridazon, methyl desphenyl chloridazon, and imidacloprid were, on average, less mobile, with maximum R of 1.5. Boscalid, chloridazon, fluopyram, and flutolanil showed a larger range of R, and R > 2.0 were observed in the shallowest part of the aquifer. Largest R were observed at the top of the aquifer and decreased with depth. K_oc values varied similarly, which indicates that sorption is not only influenced by sedimentary organic matter (SOM) content but also by its sorption reactivity. Obtained sorption parameters were substantially lower than reported in a widely used pesticide sorption database, which suggests that sorption parameters are influenced by methodological differences and variations in the sorption reactivity of SOM. The large intra-aquifer variations in pesticide sorption highlights that aquifer heterogeneity should be considered in groundwater risk assessments.

在缺氧的沙质含水层中进行了为期 6 天的现场注入实验，以评估 7 种农业常用农药和 2 种经常检测到的代谢物的吸附特性。在过去的几十年里，农药的使用发生了很大的变化，对含水层中目前使用的农药的去向知之甚少。以 1 m 的 6 个深度间隔监测注入水到达，范围从地表以下 11.4 到 32.2 m，具有不同的有机碳含量（0.057-0.91%dw），以检查含水层内的吸附变化。使用非线性最小二乘法将观察到的农药浓度拟合到平流扩散方程，从中获得延迟因子 (R)。在实验过程中，农药降解对模拟 R 没有显着影响。R  < 1.1 在所有深度。去苯基氯唑酮、甲基去苯基氯唑酮和吡虫啉的平均流动性较低，最大 R 为 1.5。啶酰菌胺、氯硝唑、氟吡菌酰胺和氟唑菌胺的R值范围较大， 含水层最浅部分的R值>2.0。在含水层顶部观察到最大的 R 并随着深度而减小。_考克值变化相似，这表明吸附不仅受沉积有机物 (SOM) 含量的影响，还受其吸附反应性的影响。获得的吸附参数大大低于广泛使用的农药吸附数据库中的报告，这表明吸附参数受方法学差异和 SOM 吸附反应性变化的影响。含水层内农药吸附的巨大变化突出表明，在地下水风险评估中应考虑含水层的异质性。