Cas du tétrachlorométhane (CCl4) détecté dans l’air ambiant : étude fondée sur des données acquises en bureau d’études spécialisé en sites et sols pollués

Abstract : Thanks to sampling campaigns carried out as part of the national methodology for managing polluted sites and soils (Ministry of Environment, Energy and the Sea, 2018), the study office IDDEA found that Carbon Tetrachloride (CCl4) was detected in ambient air at some polluted sites but also at the level of the local control sample. So why is CCl4 regularly detected? Is its presence solely related to the historical activities of the sites or is it ubiquitous? Is there a local background noise in CCl4? Although CCl4 has been banned since 1995, there are still indirect discharges via chloromethane and perchloroethylene plants. Thus, they can be found ubiquitously in the ambient air. The results of this study showed that the concentration measured in CCl4 at different selected sites are all of the same order of magnitude and range from approximately 0.2 and 0.6 μg/m3, Control samples have a concentration similar to those measured on site and are within the range of ubiquitous concentrations provided by INERIS (0.5 to 1 μg/m3). It would be due to indirect discharges but also to unknown pathways. The surveyed sites showing these trends are distributed heterogeneously in the North-West quarter of France. In addition, the sampling season can play a role in the volatility of the compounds and thus in the measured concentrations. At the health level, the methodology for polluted sites and soils is based mainly on the R1 threshold in health risk studies, but the latter is based solely on the toxicology of the molecule and does not take into account background noise. This is much lower (0.24 μg/m3) than the ubiquitous value (0.5-1 μg/m3). Thus, there may be a local and heterogeneous background noise, but many uncertainties must be taken into account: field manipulations, laboratory methods of analysis, limit of quantification, sampling time, very low representativeness of results. The data acquired by IDDEA thus make it possible to meet the expectations of its customers but not to make a clear decision on the existence of background noise.
Document type :
Master thesis
File URL :
http://docnum.univ-lorraine.fr/ulprive/BUS_M_2019_CLESSE_MARGAUX.pdf
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https://hal.univ-lorraine.fr/hal-02319642
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Submitted on : Friday, October 18, 2019 - 10:36:38 AM
Last modification on : Friday, October 18, 2019 - 10:36:38 AM

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Margaux Clesse. Cas du tétrachlorométhane (CCl4) détecté dans l’air ambiant : étude fondée sur des données acquises en bureau d’études spécialisé en sites et sols pollués. Sciences de la Terre. 2019. ⟨hal-02319642⟩

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