Field-deployed lysimeters were used to measure the concentrations of poly- and perfluoroalkyl substances (PFASs) in soil porewater at a site historically impacted with aqueous film forming foam (AFFF). Samples collected over a 49-day period showed that perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) were the PFASs with the highest concentrations in porewater, with concentrations of approximately 10,000 and 25,000 ng L⁻¹, respectively. The corresponding average mass flux to underlying groundwater observed for PFOS and PFHxS was 28,000 ± 11,000 and 92,000 ± 32,000 ng m⁻² d⁻¹, respectively. Employing the use of batch desorption isotherms (soil:water slurries) to determine desorption K_d values resulted in an overestimation of PFAS porewater concentrations by a factor for 1.4 to 4. However, using the desorption K_d values from the batch desorption isotherms in combination with a PFAS mass balance that incorporated PFAS sorption at the air-water interface resulted in improved predictions of the PFAS porewater concentrations. This improvement was most notable for PFOS, where inclusion of air-water interfacial sorption resulted in a 58% reduction in the predicted PFOS porewater concentration and predicted PFOS porewater concentrations that were identical (within the 95% confidence interval) to the lysimeter measured PFOS porewater concentration. Overall these results highlight the potentially important role of air-water interfacial sorption on PFAS migration in AFFF-impacted unsaturated soils in an in situ field setting.

现场部署的蒸渗仪用于测量历史上受水成膜泡沫 (AFFF) 影响的土壤孔隙水中的多氟烷基物质和全氟烷基物质 (PFAS) 的浓度。在 49 天期间收集的样品表明，全氟辛烷磺酸 (PFOS) 和全氟己烷磺酸 (PFHxS) 是孔隙水中浓度最高的 PFAS，浓度分别约为 10,000 和 25,000 ng L ^-1。观察到的全氟辛烷磺酸和全氟己烷磺酸相应的下层地下水平均质量通量分别为 28,000 ± 11,000 和 92,000 ± 32,000 ng m ^-2 d ^-1。采用批量解吸等温线（土壤：水浆）来确定解吸 K _d值导致 PFAS 孔隙水浓度被高估了 1.4 到 4 倍。然而，使用批量解吸等温线的解吸 K _d值与结合了 PFAS 吸附的 PFAS 质量平衡在空气-水界面上，改进了对 PFAS 孔隙水浓度的预测。这种改进对于全氟辛烷磺酸最为显着，其中包含空气-水界面吸附导致预测全氟辛烷磺酸孔隙水浓度降低 58%，预测全氟辛烷磺酸孔隙水浓度与蒸渗仪测量的全氟辛烷磺酸孔隙水相同（在 95% 置信区间内）专注。总体而言，这些结果突出了原位现场环境中空气-水界面吸附对 AFFF 影响的非饱和土壤中 PFAS 迁移的潜在重要作用。