We use a realistic fracture along with pore-scale reactive transport simulations to investigate the impact of fracture filling minerals and water-mineral reactions on in-plane groundwater flow patterns and on contaminant uptake by matrix diffusion. The results of the simulations show that sparsely distributed fracture filling calcite patches provide a significant buffering capacity against the infiltration of acidic water. The advance of the geochemical perturbation is characterized by channeling, which is partly smeared out when low Peclet numbers are used. Mineral patches have a significant impact on groundwater flow patterns as shown by the computed distributions of groundwater travel time, which are characterized by long tails. The ability of the fracture to retain contaminants by uptake due to matrix diffusion is investigated by means of two metrics: the Eulerian quantity denoted as F-factor and the Lagrangian variable known as transport resistance. F-factor is shown to provide an average single estimate of the bulk retention capacity of the fracture whereas transport resistance is characterized by a distribution, whose very long tail is related to streamlines forced to travel through very narrow throats. A reduction of up to 70% in the mean travel time and 85% in the mean transport resistance is observed as a consequence of geochemical dissolution reactions, which also lead to an overall reduction of their variability.

中文翻译：

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平移的单一现实裂缝中的水-矿物反应：基质扩散对污染物吸收的后果

我们使用真实的裂缝以及孔隙尺度的反应输运模拟来研究裂缝填充矿物和水-矿物反应对平面内地下水流动模式和基质扩散对污染物吸收的影响。模拟结果表明，稀疏分布的裂缝填充方解石斑块对酸性水的渗透具有显着的缓冲能力。地球化学扰动的推进以沟道为特征，当使用低佩克莱特数时，沟道会被部分涂抹。矿物斑块对地下水流动模式有重大影响，如计算的地下水传播时间分布所示，其特征是长尾。F因子和称为传输阻力的拉格朗日变量。显示 F因子可提供裂缝体积保持能力的平均单一估计，而传输阻力的特征在于分布，其非常长的尾部与被迫穿过非常狭窄的喉道的流线有关。由于地球化学溶解反应，平均旅行时间减少了70%，平均传输阻力减少了85%，这也导致它们的变异性总体减少。