Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, 8093, Zürich, Switzerland.
Department of Physical Chemistry, Faculty of Marine and Environmental Sciences, University of Cadiz, Campus of International Excellence of the Sea (CEI•MAR), Río San Pedro, Puerto Real, Cádiz, 11510, Spain.
Environ Pollut. 2021 Jan 15;269:116021. doi: 10.1016/j.envpol.2020.116021. Epub 2020 Nov 9.
Surfactants, after use, enter the environment through diffuse and point sources such as irrigation with treated and non-treated waste water and urban and industrial wastewater discharges. For the group of non-ionic synthetic surfactant alcohol ethoxylates (AEOs), most of the available information is restricted to the levels and fate in aquatic systems, whereas current knowledge of their behavior in soils is very limited. Here we characterize the behavior of different homologs (C12-C18) and ethoxymers (EO3, EO6, and EO8) of the AEOs through batch experiments and under unsaturated flow conditions during infiltration experiments. Experiments used two different agricultural soils from a region irrigated with reclaimed water (Guadalete River basin, SW Spain). In parallel, water flow and chemical transport were modelled using the HYDRUS-1D software package, calibrated using the infiltration experimental data. Estimates of water flow and reactive transport of all surfactants were in good agreement between infiltration experiments and simulations. The sorption process followed a Freundlich isotherm for most of the target compounds. A systematic comparison between sorption data obtained from batch and infiltration experiments revealed that the sorption coefficient (K) was generally lower in infiltration experiments, performed under environmental flow conditions, than in batch experiments in the absence of flow, whereas the exponent (β) did not show significant differences. For the low clay and organic carbon content of the soils used, no clear dependence of K on them was observed. Our work thus highlights the need to use reactive transport parameterization inferred under realistic conditions to assess the risk associated with alcohol ethoxylates in subsurface environments.
表面活性剂使用后，通过处理和未处理废水的灌溉以及城市和工业废水排放等弥散和点源进入环境。对于非离子合成表面活性剂醇乙氧基化物（AEOs）组，大多数可用信息仅限于水生系统中的水平和命运，而目前对其在土壤中的行为的了解非常有限。在这里，我们通过批处理实验和非饱和流动条件下的渗透实验来描述不同同系物（C12-C18）和乙氧基化物（EO3、EO6 和 EO8）的 AEOs 的行为。实验使用来自再生水灌溉地区（西班牙西南部瓜达莱特河流域）的两种不同农业土壤。同时，使用 HYDRUS-1D 软件包模拟水流和化学传输，并使用渗透实验数据进行校准。所有表面活性剂的水流和反应性传输估计值在渗透实验和模拟之间非常吻合。吸附过程对于大多数目标化合物都遵循 Freundlich 等温线。从批量和渗透实验中获得的吸附数据的系统比较表明，在环境流动条件下进行的渗透实验中，吸附系数（K）通常低于不存在流动的批量实验，而指数（β）则没有显示出显著差异。对于所用土壤的低粘土和有机碳含量，没有观察到 K 值对它们的明显依赖。因此，我们的工作强调需要使用在实际条件下推断的反应性传输参数化来评估地下环境中醇乙氧基化物相关的风险。
