Plume persistence due to aquitard back diffusion following dense nonaqueous phase liquid source removal or isolation
Plume persistence due to aquitard back diffusion following dense nonaqueous phase liquid source removal or isolation
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DOI：
10.1029/2005wr004224
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发表时间：
2005-12-06
影响因子：
5.4
通讯作者：
Parker, BL
中科院分区：
文献类型：
--
作者：
Chapman, SW;Parker, BL
[1]1994年底，在康涅狄格州粘质淤泥含水层之上的砂质含水层上的一个工业现场，通过安装钢板桩围护结构，在含水层底部隔离了三氯乙烯稠密非水相液体区(DNAPL)。作为对DNAPL隔离的响应，位于约330米下坡的三个含水层监测井在接下来的2-3年内三氯乙烯浓度从5000到30,000微克/L之间的三氯乙烯浓度下降到200到2000微克/升之间的稳定值。这表明含水层的垂直后向扩散与水平平流和垂直横向扩散相结合，解释了TCE在含水层中的分布，含水层TCE将在几个世纪内保持在MCL之上。
[1] At an industrial site on a sand aquifer overlying a clayey silt aquitard in Connecticut, a zone of trichloroethylene dense nonaqueous phase liquid (DNAPL) at the aquifer bottom was isolated in late 1994 by installation of a steel sheet piling enclosure. In response to this DNAPL isolation, three aquifer monitoring wells located approximately 330 m downgradient exhibited strong TCE declines over the next 2 - 3 years, from trichloroethylene ( TCE) concentrations between 5000 and 30,000 mu g/L to values leveling off between 200 and 2000 mu g/L. TCE concentrations from analysis of vertical cores from the aquitard below the plume and also from depth-discrete multilevel systems in the aquifer sampled in 2000 were represented in a numerical model. This shows that vertical back diffusion from the aquitard combined with horizontal advection and vertical transverse dispersion account for the TCE distribution in the aquifer and that the aquifer TCE will remain much above the MCL for centuries.