PDF(Pubmed)
Abstract：
Recalcitrant groundwater contamination is a common problem at hazardous waste sites worldwide. Groundwater contamination persists despite decades of remediation efforts at many sites because contaminants sorbed or dissolved within low-conductivity zones can back diffuse into high-conductivity zones, and therefore act as a continuing source of contamination to flowing groundwater. A review of the available literature on remediation of plume persistence due to back diffusion was conducted, and four sites were selected as case studies. Remediation at the sites included pump and treat, enhanced bioremediation, and thermal treatment. Our review highlights that a relatively small number of sites have been studied in sufficient detail to fully evaluate remediation of back diffusion; however, three general conclusions can be made based on the review. First, it is difficult to assess the significance of back diffusion without sufficient data to distinguish between multiple factors contributing to contaminant rebound and plume persistence. Second, high-resolution vertical samples are decidedly valuable for back diffusion assessment but are generally lacking in post-treatment assessments. Third, complete contaminant mass removal from back diffusion sources may not always be possible. Partial contaminant mass removal may nonetheless have potential benefits, similar to partial mass removal from primary DNAPL source zones.
摘要：
顽固的地下水污染是全球危险废物场所的常见问题。尽管在许多地点进行了数十年的补救工作，但地下水污染仍然存在，因为在低电导率区域内吸附或溶解的污染物可能会扩散到高电导率区域，因此成为流动地下水的持续污染源。对由于反向扩散而导致的羽流持久性修复的现有文献进行了综述，并选择了四个地点作为案例研究。现场的修复包括泵和治疗，强化生物修复，和热处理。我们的审查强调，已经对相对较少的站点进行了足够详细的研究，以全面评估反扩散的补救；但是，根据审查，可以得出三个一般性结论。首先,如果没有足够的数据来区分导致污染物反弹和羽流持久性的多个因素，很难评估反向扩散的重要性。第二,高分辨率垂直样品对于反向扩散评估无疑是有价值的，但通常缺乏后处理评估。第三，从反向扩散源完全去除污染物质量可能并不总是可能的。尽管如此，部分污染物质量去除可能会有潜在的好处，类似于主要DNAPL源区的部分质量去除。
