Cavelan Amélie, Faure Pierre, Lorgeoux Catherine, Colombano Stéfan, Deparis Jacques, Davarzani Dorian, Enjelvin Noële, Oltean Constantin, Tinet Anne-Julie, Domptail Fabien, Golfier Fabrice
Université de Lorraine, CNRS, LIEC, France; BRGM, France.
Université de Lorraine, CNRS, LIEC, France.
J Contam Hydrol. 2024 Mar;262:104319. doi: 10.1016/j.jconhyd.2024.104319. Epub 2024 Feb 9.
Light-Non-Aqueous phase liquids (LNAPLs) are important soil contamination sources, and groundwater fluctuations may significantly affect their migration and release. However, the risk assessment remains complex due to the continuous three-phase fluid redistribution caused by water table level variations. Hence, monitoring methods must be improved to integrate better the LNAPL multi-compound and multi-phase aspects tied to the groundwater level dynamics. For this purpose, a lysimetric contaminated soil column (2 m) combining in-situ monitoring (electrical permittivity, soil moisture, temperature, pH, Eh), direct water and gas sampling and analyses (GC/MS-TQD, μGC) in monitoring well, gas collection chambers, and suction probes) were developed. This experiment assesses in an integrated way how controlled rainfalls and water table fluctuation patterns may affect LNAPL vertical soil saturation distribution and release. Coupling these methods permitted the investigation of the effects of rainwater infiltration and water table level fluctuation on contaminated soil oxygen turnover, LNAPL contaminants' soil distribution and remobilization towards the dissolved and the gaseous phase, and the estimate of the LNAPL source attenuation rate. Hence, 7.5% of the contamination was remobilized towards the dissolved and gaseous phase after 120 days. During the experiment, groundwater level variations were responsible for the free LNAPL soil spreading and trapping, modifying dissolved LNAPL concentrations. Nevertheless, part of the dissolved contamination was rapidly biodegraded, leaving only the most bio-resistant components in water. This result highlights the importance of developing new experimental devices designed to assess the effect of climate-related parameters on LNAPL fate at contaminated sites.
轻质非水相液体（LNAPLs）是重要的土壤污染源，地下水位波动可能会显著影响其迁移和释放。然而，由于地下水位变化导致的三相流体持续重新分布，风险评估仍然很复杂。因此，必须改进监测方法，以便更好地整合与地下水位动态相关的LNAPL多化合物和多相方面。为此，开发了一种渗压计污染土壤柱（2米），结合原位监测（介电常数、土壤湿度、温度、pH值、氧化还原电位）、在监测井、气体收集室和吸力探头中进行直接水和气体采样及分析（气相色谱/质谱-三重四极杆、微型气相色谱）。本实验以综合方式评估了受控降雨和地下水位波动模式如何影响LNAPL在土壤中的垂直饱和度分布和释放。将这些方法结合起来，可以研究雨水入渗和地下水位波动对污染土壤中氧气周转、LNAPL污染物在土壤中的分布以及向溶解相和气相的再迁移的影响，以及估算LNAPL源衰减率。因此，120天后，7.5%的污染物向溶解相和气相再迁移。在实验过程中，地下水位变化导致了游离LNAPL在土壤中的扩散和截留，改变了溶解态LNAPL的浓度。然而，部分溶解态污染物迅速被生物降解，水中仅留下最具生物抗性的成分。这一结果凸显了开发新的实验装置以评估气候相关参数对污染场地中LNAPL归宿影响的重要性。
