Université Paris-Saclay, CEA, Service d'Étude du Comportement des Radionucléides, 91191, Gif-sur-Yvette, France.
Andra, R&D Division, Parc de la Croix Blanche, 92298, Châtenay-Malabry, France.
Chemosphere. 2021 Jul;275:130048. doi: 10.1016/j.chemosphere.2021.130048. Epub 2021 Feb 22.
The migration of organic compounds in soils is a major concern in several environmental issues. Contaminants display distinct behaviours as regards to their specific affinities towards soils constituents. The retention mechanism of hydrophobic compounds by natural organic matter is well known. The retention of ionizable compounds is mainly related to oxides and clay minerals, even if less documented in reductive media. In this work, we investigated the migration of organic compounds in a soft clay-rich sedimentary rock (Tégulines clay, France). The aim was to determine the relative contributions of natural sorbents on retention, and eventual correlations with solutes properties. Both hydrophobic compounds (toluene, benzene, naphthalene) and hydrophilic species (adipate, oxalate, ortho-phthalate, benzoate) were investigated, using batch and diffusion experiments. The retention of neutral aromatic compounds correlates with their lipophilicity (log P), confirming that absorption mechanism prevails, despite a low content of natural organic matter (≤0.5%). A low retention of ionizable compounds was quantified on Tégulines clay. The eventual discrepancies between data acquired on crushed rock and solid samples are discussed. Low effective diffusion coefficients are quantified. These values hint on the relative contributions of steric and electrostatic exclusion, despite a large pore size in such "soft" clay-rock. Overall, the dataset illustrates a general scheme for assessing the migration over a wide variety of organic compounds. This approach may be useful for predictive modelling of the fate of organic compounds in environmental media.
有机化合物在土壤中的迁移是几个环境问题中的主要关注点。污染物表现出明显的行为，因为它们对土壤成分具有特定的亲和力。天然有机物对疏水性化合物的保留机制是众所周知的。可电离化合物的保留主要与氧化物和粘土矿物有关，尽管在还原介质中的记录较少。在这项工作中，我们研究了有机化合物在富含软粘土的沉积岩（法国 Tégulines 粘土）中的迁移。目的是确定天然吸附剂对保留的相对贡献，以及与溶质性质的可能相关性。使用批量和扩散实验研究了疏水性化合物（甲苯、苯、萘）和亲水物质（己二酸、草酸、邻苯二甲酸、苯甲酸）。中性芳香族化合物的保留与它们的亲脂性（log P）相关，这证实了吸收机制占主导地位，尽管天然有机物含量低（≤0.5%）。在 Tégulines 粘土上定量了对可电离化合物的低保留。还讨论了在粉碎岩石和固体样品上获得的数据之间的差异。低有效扩散系数被量化。这些值暗示了空间位阻和静电排斥的相对贡献，尽管在这种“软”粘土岩中孔径较大。总体而言，该数据集说明了评估各种有机化合物迁移的一般方案。这种方法可用于预测有机化合物在环境介质中的命运的建模。
