Dong Yanhui, Xia Teng, Meng Jian, Mao Deqiang
Key Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China.
College of Earth and Planetary Science, University of Chinese Academy of Sciences, Beijing, China.
Sci Rep. 2024 Aug 6;14(1):18268. doi: 10.1038/s41598-024-66782-8.
Light non-aqueous phase liquids (LNAPLs) that infiltrate into the subsurface are commonly described in two distinct zones: the source zone and the plume zone. A precise differentiation between these zones is essential for constraining further migration and selecting an effective remediation method. In this study, we employ the induced polarization (IP) method to characterize the contaminants. Six time domain IP survey lines were conducted at a former chemical plant contaminated with LNAPLs. Even though the contaminated areas corresponding to BTEX concentration above 180 mg/kg are less than 5 mS/m, the source and plume zones cannot be distinguished by conductivity alone. However, a noticeable difference in phase ( ) between the two zones is observed, and the threshold phase value corresponding to a critical concentration of 450 mg/kg is 20 mrad. Moreover, the normalized chargeability ( ) threshold for the source zone is 80 mS/m, and the corresponding differences between the source and plume zones are more significant than those in . These results illustrate that changes in polarization characteristics associated with BTEX concentrations can aid in further distinguishing between the source and plume zones. Ultimately, it is concluded that IP imaging is a well-suited method for LNAPL investigations that permits an improved characterization of different contaminated zones, which can facilitate the optimization of drillings for further site assessment and remediation.
渗入地下的轻质非水相液体（LNAPLs）通常在两个不同区域被描述：源区和羽流区。精确区分这些区域对于限制污染物进一步迁移和选择有效的修复方法至关重要。在本研究中，我们采用激发极化（IP）方法来表征污染物。在一个曾被LNAPLs污染的化工厂进行了六条时域IP测量线的测量。尽管对应于苯系物浓度高于180mg/kg的污染区域电导率小于5mS/m，但仅通过电导率无法区分源区和羽流区。然而，观察到两个区域之间在相位（ ）上有明显差异，对应于450mg/kg临界浓度的阈值相位值为20mrad。此外，源区的归一化充电率（ ）阈值为80mS/m，且源区和羽流区之间相应的 差异比 中的差异更显著。这些结果表明，与苯系物浓度相关的极化特性变化有助于进一步区分源区和羽流区。最终得出结论，IP成像对于LNAPL调查是一种非常合适的方法，它能够更好地表征不同的污染区域，这有助于优化钻探以进行进一步的场地评估和修复。
