Laboratory Flushing Tests of Dissolved Contaminants in Heterogeneous Porous Media with Low-Conductivity Zones
Laboratory Flushing Tests of Dissolved Contaminants in Heterogeneous Porous Media with Low-Conductivity Zones
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低电导率区非均质多孔介质中溶解污染物的实验室冲洗试验
DOI：
10.1007/s11270-023-06236-5
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发表时间：
2023
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影响因子：
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通讯作者：
Inoue Kazuya
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作者：
Kurasawa Tomoki;Takahashi Yoshitaro;Suzuki Mariko;Inoue Kazuya
污染物滞留在粘土透镜体和弱透水层等低传导率区域内，会极大地影响地下水的补救过程。本研究的目的是实验研究的几何形状的低电导率区，电导率的对比度，和溶质冲洗的流动状态的影响。我们在包含圆柱形低电导率区（即，低K区）嵌入在高导电介质中（即，高K区）。考虑了七种模型，包括四种高电导率对比度（SL、SS、LL和LS）、一种中等对比度（LLM）、一种低对比度（LLL）和一种均匀（H）模型。在两个流速（Q= 0.6和26立方厘米/分钟）进行实验，为每个非均质模型（SL，SS，LL，LS，LLM，和LLL），以比较在不同的流动状态的冲洗过程。首先，我们验证了我们的实验的有效性，通过比较的H模型的结果从解析解与我们的实验。高对比度模型的结果表明，对于扩散为主的制度（Q= 0.6 cm 3/min），所需的孔隙体积注入（PVI）冲洗出溶质质量是远远小于在对流为主的制度（Q= 26 cm 3/min）。为了评估四种高对比度模型冲洗溶质所需的孔体积，我们引入了一个参数P0.01，定义为在低K区中部相对浓度变为0.01所需的PVI。对于扩散主导的区域，P0.01随着低K区比表面积的增加而减小，而在平流主导的区域，它随低K带长度的增加而增加。我们还确定的重要性的影响ofKcontrast溶质保留通过比较三种不同的模型ofKcontrast（LL，LLM，和LLL）的结果。
The retention of contaminants within low-conductivity regions such as clay lenses and aquitards can greatly affect groundwater remediation processes. The aim of this study was to experimentally investigate the effects of the geometry of low-conductivity zones, conductivity contrast, and flow regime on solute flushing. We conducted a series of flushing tests in cylindrical models containing a cylindrical low-conductivity zone (i.e., low-Kzone) embedded in a highly conductive medium (i.e., high-Kzone). Seven models comprising four high-conductivity-contrast (SL, SS, LL, and LS), one medium-contrast (LLM), one low-contrast (LLL), and one homogeneous (H) models were considered. Experiments were conducted at two flow rates (Q= 0.6 and 26 cm3/min) for each heterogeneous model (SL, SS, LL, LS, LLM, and LLL) to compare the flushing processes in different flow regimes. First, we verified the validity of our experiments by comparing the results of the H model from an analytical solution with our experiment. The results of the high-contrast models showed that for a diffusion-dominated regime (Q= 0.6 cm3/min), the pore volume injected (PVI) required to flush out solute mass was much smaller than that in an advection-dominated regime (Q= 26 cm3/min). To evaluate the pore volumes required to flush out solutes for the four high-contrast models, we introduced a parameterP0.01, which is defined as the PVI needed for the relative concentration to become 0.01 at the middle of the low-Kzone.P0.01decreases with increasing the specific surface area of the low-Kzone for diffusion-dominated regimes, while it increases with increasing the length of the low-Kzone for advection-dominated regimes. We also determined the importance of the effect ofKcontrast on solute retention by comparing the results of three different models ofKcontrast (LL, LLM, and LLL).