School of Earth Sciences and Engineering, Hohai University, Nanjing, 210098, China.
Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, N2L 3G1, Canada.
Environ Sci Pollut Res Int. 2024 Jul;31(33):46061-46072. doi: 10.1007/s11356-024-34284-9. Epub 2024 Jul 9.
Research on the migration behaviors of contaminants in the aquitard has been deficient for an extended period. Clay is commonly employed as an impermeable layer or barrier to stop the migration of contaminants. However, under certain conditions, the clay layer may exhibit permeability to water, thereby allowing contaminants to infiltrate and potentially contaminate adjacent aquifers. Consequently, it holds immense importance to scrutinize and investigate the migration characteristics of light non-aqueous phase liquid (LNAPL) within the aquitard for the purposes of groundwater pollution control and remediation. To evaluate the environmental risk posed by organic contaminants in the aquitard, an experimental model was formulated and devised to monitor the LNAPL concentration in the aquitard under pumping conditions. The correlation between pumping rate and LNAPL concentration was investigated. A self-developed plexiglass sandbox model was used to simulate the migration characteristics of LNAPL in the aquitard under pumping conditions. Four experimental scenarios were designed, varying pumping rates, aquitard thicknesses, and groundwater level changes. The LNAPL concentration curve was derived by systematically tracking and analyzing LNAPL levels at various locations within the aquitard. The results indicated that higher pumping rates corresponded to increased migration of LNAPL, resulting in greater LNAPL ingress into the pumping well during extraction. A thicker aquitard demonstrated a more pronounced inhibitory effect on LNAPL, leading to an extended penetration time of LNAPL within the aquitard. The drawdown within the aquitard exerted a discernible influence on LNAPL migration, with the LNAPL concentration continuing to decrease in tandem with declining water levels during pumping. These research findings can establish a scientific foundation for the control and remediation of contaminants within aquitards.
含水层阻滞中污染物迁移行为的研究长期以来一直存在不足。黏土通常被用作防渗层或阻挡层，以阻止污染物的迁移。然而，在某些条件下，黏土层可能会表现出对水的渗透性，从而允许污染物渗透并可能污染相邻的含水层。因此，仔细研究和调查含水层中轻质非水相液体（LNAPL）的迁移特征对于地下水污染控制和修复至关重要。为了评估含水层中有机污染物带来的环境风险，构建并设计了一个实验模型，以监测在抽水条件下含水层中 LNAPL 的浓度。研究了抽提速率与 LNAPL 浓度之间的相关性。使用自行研制的有机玻璃沙箱模型模拟了在抽水条件下 LNAPL 在含水层中的迁移特征。设计了四个实验场景，改变了抽提速率、含水层厚度和地下水位变化。通过系统地跟踪和分析含水层中各个位置的 LNAPL 水平，得出了 LNAPL 浓度曲线。结果表明，较高的抽提速率对应于 LNAPL 的更大迁移，导致在提取过程中有更多的 LNAPL 进入抽水井。较厚的含水层对 LNAPL 表现出更明显的抑制作用，导致 LNAPL 在含水层中的穿透时间延长。含水层中的水位下降对 LNAPL 迁移有明显的影响，随着水位下降，在抽水过程中 LNAPL 浓度持续下降。这些研究结果可以为含水层中污染物的控制和修复提供科学依据。
