Univ. Lille CNRS, UMR 8516 - LASIRE, Equipe Physico-Chimie de l'Environnement, Lille F-59000, France; BRGM (French Geological Survey), 59810 Lesquin, France.
BRGM (French Geological Survey), 59810 Lesquin, France.
Sci Total Environ. 2021 Feb 25;757:143742. doi: 10.1016/j.scitotenv.2020.143742. Epub 2020 Nov 14.
The Chalk aquifer used for drinking-water production in the southwest of the Lille European Metropolis is threatened by the presence of chlorinated aliphatic hydrocarbons (CHCs), their concentrations in groundwater regularly exceeding the regulatory limits for drinking water in France. This hinders its use for drinking-water production. Understanding the dynamics and spatial distribution of CHC in the aquifer is a key factor for resource sustainability. For that purpose, an intensive monitoring was undertaken in several well fields and at different depths over eight years. To assess a possible migration and/or degradation of the compounds, the water column in several wells was sampled at various depths with passive samplers. Furthermore, CHC degradation mechanisms were investigated with compound-specific carbon-isotope analysis. The CHC concentrations and their distributions in the area depend on past and current industrial activity, causing plumes emphasized by pumping in the wells, such plumes being multi-source with no identified origin in most wells. In the south area of Les Ansereuilles, reductive dechlorination of tetrachloroethylene from a former industrial laundry highly impacted the surrounding area with its main degradation product cis-1,2-dichloroethylene. The same area is also affected by tetrachlroroethylene from several industrial laundries, textile factories and dyeing industries with also an anaerobic degradation. In the northern part of Les Ansereuilles, tetrachloroethylene, trichloroethane, trichloroethylene and 1,1-dichloroethylene were found as primary products, whereas cis-1,2-dichloroethylene appears to be an anaerobic degradation product of TCE. The other well fields (Houplin-Ancoisne, Seclin and Emmerin) are less impacted by CHC pollution, and it was shown that no CHC degradation occurred in the wells. However, the stratification of CHCs in the well-water columns, their constant concentration values over time caused by the large amount of available CHCs, and the minor degradation occurring in wells are of concern for water operators in the future.
西南里尔欧洲都会区用于饮用水生产的粉笔含水层受到氯化脂肪烃 (CHC) 的威胁，其地下水中的浓度经常超过法国饮用水的规定限值。这阻碍了它用于饮用水生产。了解含水层中 CHC 的动态和空间分布是资源可持续性的关键因素。为此，在八年的时间里，在几个井场和不同深度进行了密集监测。为了评估化合物的可能迁移和/或降解，使用被动采样器在几个井中不同深度采集水柱样品。此外，还通过化合物特异性碳同位素分析研究了 CHC 降解机制。该地区的 CHC 浓度及其分布取决于过去和当前的工业活动，导致在井中抽汲时强调的羽流，这些羽流是多源的，在大多数井中没有确定的来源。在 Les Ansereuilles 的南部地区，来自一家前工业洗衣店的四氯乙烯的还原脱氯强烈影响了周围地区，其主要降解产物顺式-1,2-二氯乙烯。同一地区还受到来自几个工业洗衣店、纺织厂和染整厂的四氯乙烯的影响，也存在厌氧降解。在 Les Ansereuilles 的北部，发现四氯乙烯、三氯乙烷、三氯乙烯和 1,1-二氯乙烯是主要产物，而顺式-1,2-二氯乙烯似乎是 TCE 的厌氧降解产物。其他井场（Houplin-Ancoisne、Seclin 和 Emmerin）受 CHC 污染的影响较小，并且表明在井中没有发生 CHC 降解。然而，CHC 在井水中柱中的分层、长时间内浓度保持不变，这是由于大量可用的 CHC，以及在井中发生的少量降解，这对未来的水运营商构成了关注。
