Towards predicting DNAPL source zone formation to improve plume assessment: Using robust laboratory and numerical experiments to evaluate the relevance of retention curve characteristics.
Towards predicting DNAPL source zone formation to improve plume assessment: Using robust laboratory and numerical experiments to evaluate the relevance of retention curve characteristics.
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DOI：
10.1016/j.jhazmat.2020.124741
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发表时间：
2020-12
影响因子：
13.6
通讯作者：
Christian Engelmann;Kaveh Sookhak Lari;Luísa Schmidt;C. Werth;M. Walther
中科院分区：
文献类型：
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作者：
Christian Engelmann;Kaveh Sookhak Lari;Luísa Schmidt;C. Werth;M. Walther
我们进行了多个实验室试验，在一个强大的和可重复的实验布局，以研究致密非水相液体（DNAPL）源区的形成。我们扩展了图像处理和分析框架，从反射光学成像数据中导出DNAPL饱和度分布，体积平衡偏差<5.07%。我们使用多相流模型来模拟源区形成的蒙特卡罗方法，其中参数空间由保留曲线参数的变化来定义。积分和几何措施被用来表征源区和实施到一个多标准的目标函数。后者表明，当DNAPL有效饱和度值> 0.04时，观测数据与模拟结果吻合较好，尤其是DNAPL运移的早期阶段。定义DNAPL-水保留曲线的参数随时间恒定的常见假设未得到证实。一旦DNAPL合并开始，参数空间中的最佳拟合与早期DNAPL迁移阶段相比显着不同。我们怀疑更复杂的过程（例如，毛细管滞后、吸附）在池形成期间变得相关。我们的研究结果显示，在灰度-DNAPL饱和度关系定义和实验室估计的DNAPL-水分保留曲线参数，以克服目前的局限性，描述DNAPL源区形成的赤字。
We conducted multiple laboratory trials in a robust and repeatable experimental layout to study dense non-aqueous phase liquid (DNAPL) source zone formation. We extended an image processing and analysis framework to derive DNAPL saturation distributions from reflective optical imaging data, with volume balance deviations < 5.07%. We used a multiphase flow model to simulate source zone formation in a Monte Carlo approach, where the parameter space was defined by the variation of retention curve parameters. Integral and geometric measures were used to characterize the source zones and implemented into a multi-criteria objective function. The latter showed good agreement between observation data and simulation results for effective DNAPL saturation values > 0.04, especially for early stages of DNAPL migration. The common hypothesis that parameters defining the DNAPL-water retention curves are constant over time was not confirmed. Once DNAPL pooling started, the optimal fit in the parameter space was significantly different compared to the earlier DNAPL migration stages. We suspect more complex processes (e.g., capillary hysteresis, adsorption) to become relevant during pool formation. Our results reveal deficits in the grayscale-DNAPL saturation relationship definition and laboratory estimation of DNAPL-water retention curve parameters to overcome current limitations to describe DNAPL source zone formation.