Putzlocher R, Kueper B H, Reynolds D A
Department of Civil Engineering, Queen's University, Kingston, Ontario, Canada K7L 3N6.
J Contam Hydrol. 2006 Dec 15;88(3-4):321-36. doi: 10.1016/j.jconhyd.2006.07.009. Epub 2006 Sep 18.
Numerical simulation is used to examine the relative velocities of DNAPL and aqueous phase plumes in sandy aquifers where lateral spreading of DNAPL has occurred at the base of the aquifer. The scenario being modeled is one where a permeable aquifer is underlain by a sloping aquitard, which results in lateral migration of the DNAPL down the slope, in addition to lateral migration of an aqueous phase plume subject to a specified hydraulic gradient. A sensitivity analysis is presented to the impacts of both DNAPL properties and geologic properties. The most important chemical properties governing the relative velocities of the DNAPL and the shallow aqueous phase plume are the DNAPL viscosity and the aqueous component soil-water partition coefficient (Kd). The dip of the underlying aquitard was found to be relatively unimportant, at least for the range of values studied. The scenario under consideration can be important in conceptual model development and remedial design, as in certain cases DNAPL could be migrating in areas without the evidence of a well-developed aqueous phase plume. The implication of this work is that the absence of a shallow aqueous phase plume directly downgradient of a DNAPL source zone does not rule out the possibility of deep occurrences of DNAPL beyond the shallow monitoring well network. A further finding of this study is that the occurrence of a highly sorbing compound in groundwater at virtually any concentration may indicate the immediate upgradient presence of residual or pooled DNAPL.
数值模拟用于研究砂质含水层中重质非水相液体（DNAPL）和水相羽流的相对速度，在该含水层底部已发生DNAPL的横向扩散。所模拟的场景是，一个渗透性含水层位于倾斜的隔水层之上，这导致DNAPL沿斜坡向下横向迁移，此外，水相羽流在指定水力梯度作用下也会横向迁移。针对DNAPL性质和地质性质的影响进行了敏感性分析。控制DNAPL和浅层水相羽流相对速度的最重要化学性质是DNAPL粘度和水相组分的土壤-水分配系数（Kd）。发现下层隔水层的倾角相对不太重要，至少在所研究的值范围内是这样。所考虑的场景在概念模型开发和修复设计中可能很重要，因为在某些情况下，DNAPL可能在没有发育良好的水相羽流证据的区域迁移。这项工作的意义在于，在DNAPL源区直接下游没有浅层水相羽流，并不排除在浅层监测井网络之外深层存在DNAPL的可能性。本研究的另一个发现是，地下水中几乎任何浓度的高吸附性化合物的出现，可能表明在其上游紧邻处存在残留或聚集的DNAPL。
