Chen X, Jawitz J W
Soil and Water Science Department, University of Florida, Gainesville, Florida 32611, USA.
Environ Sci Technol. 2008 Jul 15;42(14):5285-91. doi: 10.1021/es7029653.
Reactive tracer tests were conducted to evaluate the relationship between contaminant mass reduction, Rm, and flux reduction, Rj, in laboratory experiments with porous media contaminated with a dense nonaqueous phase liquid (DNAPL). The reduction in groundwater contaminant flux resulting from partial mass removal was obtained from continuous and pulsed cosolvent and surfactant flushing dissolution tests in laboratory flow chambers packed with heterogeneous porous media. Using the streamtubes concept a Lagrangian analytical solution was applied to study the contaminant dissolution. The analytical solution was independently parametrized using nonreactive and reactive tracertests and the predicted dissolution was compared to the observed data. Analytical solution parameters related to aquifer hydrodynamic heterogeneities were determined from a nonreactive tracer, while those related to DNAPL spatial distribution heterogeneity were obtained from a reactive tracer. Reactive travel time variance, derived from this combination of tracers, was used to predict the relationship between Rm and Rj. Predictions based on the tracer tests closely matched measured dissolution data, suggesting that tracers can be used to characterize the DNAPL spatial distribution heterogeneity controlling the dissolution behavior. Experimental results demonstrated that increased reactive travel time variance led to greater flux reduction for a given partial mass removal.
进行了反应性示踪剂试验，以评估在含有致密非水相液体（DNAPL）的多孔介质实验室实验中，污染物质量减少量（Rm）与通量减少量（Rj）之间的关系。通过在填充有非均质多孔介质的实验室流动室中进行连续和脉冲共溶剂及表面活性剂冲洗溶解试验，获得了因部分质量去除导致的地下水污染物通量减少量。利用流管概念，应用拉格朗日解析解来研究污染物溶解。该解析解通过非反应性和反应性示踪剂试验独立参数化，并将预测的溶解情况与观测数据进行比较。与含水层水动力非均质性相关的解析解参数由非反应性示踪剂确定，而与DNAPL空间分布非均质性相关的参数则从反应性示踪剂获得。由这种示踪剂组合得出的反应性运移时间方差，用于预测Rm与Rj之间的关系。基于示踪剂试验的预测与实测溶解数据紧密匹配，表明示踪剂可用于表征控制溶解行为的DNAPL空间分布非均质性。实验结果表明，对于给定的部分质量去除，反应性运移时间方差增加会导致通量减少量更大。
