Casali Center of Applied Chemistry, The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
Casali Center of Applied Chemistry, The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel; Mekorot, Israel National Water Company. LTD., Israel.
Chemosphere. 2018 Jan;190:383-392. doi: 10.1016/j.chemosphere.2017.10.010. Epub 2017 Oct 3.
Trace organic compounds in effluents, water streams and aquifers are amply reported. However, the mobile pool of Emerging Organic Contaminants (EOCs) in the deep parts of the vadose zone is hard to estimate, due to difficulties in extraction of sufficient quantity of pore water. Here, we present a new methodology for depth profiling of EOCs in pore water by Positive Displacement Extraction (PDE): Pore water extraction from unsaturated soil samples is carried out by withdrawal of soil cores by direct-push drilling and infiltrating the core by organics free water. We show that EOC concentrations in the water eluted in the plateau region of the inverse breakthrough curve is equal to their pore water concentrations. The method was previously validated for DOC extraction, and here the scope of the methodology is extended to pore water extraction for organic pollutants analysis. Method characteristics and validation were carried out with atrazine, simazine, carbamazepine, venlafaxine, O-desmethylvenlafaxine and caffeine in the concentration range of several ng to several μg/liter. Validation was carried out by laboratory experiments on three different soils (sandy, sandy-clayey and clayey). Field studies in the vadose zone of a SAT system provided 27 m deep EOC profiles with less than 1.5 m spatial resolution. During the percolation treatment, carbamazepine remained persistent, while the other studied EOCs were attenuated to the extent of 50-99%.The highest degradation rate of all studied EOCs was in the aerobic zone. EOC levels based on PDE and extraction by centrifugation were compared, showing a positive bias for centrifugation.
废水中、水流中和含水层中的痕量有机化合物已有大量报道。然而，由于难以从非饱和土壤样品中提取足够数量的孔隙水，很难估计包气带深部易流动新兴有机污染物（EOCs）的移动池。在这里，我们提出了一种通过正置换萃取（PDE）对孔隙水中 EOC 进行深度剖析的新方法：通过直接推钻提取非饱和土壤样品中的孔隙水，并使核心渗透无有机物水。我们表明，反向突破曲线平台区洗脱的水中的 EOC 浓度与其孔隙水浓度相等。该方法之前已通过 DOC 提取进行了验证，在此将方法的范围扩展到用于有机污染物分析的孔隙水提取。采用莠去津、西玛津、卡马西平、文拉法辛、O-去甲文拉法辛和咖啡因在几纳克到几微克/升的浓度范围内进行了方法特征和验证的实验室实验。在三种不同的土壤（沙质、沙质-粘质和粘质）上进行了验证实验。SAT 系统包气带中的现场研究提供了 27 米深的 EOC 剖面，空间分辨率小于 1.5 米。在渗滤处理过程中，卡马西平保持持久性，而其他研究的 EOCs 则衰减了 50-99%。所有研究的 EOCs 中降解率最高的是好氧区。基于 PDE 和离心提取的 EOC 水平进行了比较，离心提取显示出正偏。
