New experimentations to assess the effect of groundwater level fluctuations on light petroleum contaminants (LNAPLs) mobilization in contaminated soils and groundwaters in the climate change context - Université de Lorraine Accéder directement au contenu
Communication Dans Un Congrès Année : 2022

New experimentations to assess the effect of groundwater level fluctuations on light petroleum contaminants (LNAPLs) mobilization in contaminated soils and groundwaters in the climate change context

Catherine Lorgeoux
  • Fonction : Auteur
  • PersonId : 1127449
Anne-Julie Tinet
Constantin Oltéan
  • Fonction : Auteur
Noële Enjelvin
Fabrice Golfier

Résumé

Context: Light-non-aqueous phase liquids (LNAPLs) are an important source of soil and groundwater pollution worldwide, but their remediation remains complex and not always successful. At contaminated sites, significant fluctuations of the soil bio/geochemical properties and spatial-temporal variations of the pollutant saturation occur, depending on the LNAPL phase (pure phase above the groundwater, dissolved plume, residual droplets). Hence, the real pollutant soil saturation often differs from the LNAPL thickness measured in monitoring wells, and gaps exist between results from modeling and site monitoring. Furthermore, the multiple imbibition/drainage cycles caused by seasonal (or pump-induced) groundwater level variations also affect the spreading of the contaminants across the soil, favoring the LNAPL release to the air and groundwater. The relation between the groundwater variation dynamic and the LNAPL mobilization mechanisms needs to be further understood, especially in the climate change context where increased groundwater fluctuations are expected (increasing groundwater use, extreme events, changes in precipitation, and recharge patterns). Innovation: In this context, we present a new experimental system combining geophysical (electrical conductivity and permittivity), in-situ physical-chemical (pH, temperature, RedOx), and geochemical monitoring (gas and water analysis: µGC, GC-MS, COD) of two soil columns (2m3) contaminated by diesel fuel during different climatic scenarios to assess the effect of groundwater level fluctuations on light petroleum contaminants (LNAPL) mobilization in the climate change context. One of the scenarios is based on regional climate records of precipitations and groundwater table fluctuations intensity while the other is based on the most extreme IPCC climate predictions. Objectives: This work aims to introduce an intermediate scale between laboratory experiments and the real complexity of contaminated sites to meet two major objectives: (i) evaluate and compare the different monitoring methods that can be used at contaminated sites. (ii) Allow a better characterization and prediction of the LNAPL dynamics at contaminated sites in current and future climatic conditions. This project will make it possible to strengthen the recommendations concerning the characterization and monitoring programs for hydrocarbons polluted sites. Results: The first months of monitoring reveal for example a decrease in the floating LNAPL thickness in monitoring wells as the groundwater table fluctuates, suggesting a spreading of the pollutants through the fluctuation zones. This phenomenon is accompanied by an increase in the gaseous surface emissions, especially for the most extreme scenario. This indicates a more important LNAPL remobilization towards the gas phase under climate change conditions. Water samples analyses (GC-MS, DOC) and geophysical data processing should soon lead to a better understanding of the effect of the intensity of groundwater table fluctuations on LNAPLs mobilization processes in the climate change context. These results will be presented to show the potential of the device and the first conclusions will be given about the effect of climate change on LANPL mobilization processes at contaminated sites.
Fichier non déposé

Dates et versions

hal-03752664 , version 1 (17-08-2022)

Identifiants

  • HAL Id : hal-03752664 , version 1

Citer

Amélie Cavelan, Stéfan Colombano, Hossein Davarzani, Jacques Deparis, Catherine Lorgeoux, et al.. New experimentations to assess the effect of groundwater level fluctuations on light petroleum contaminants (LNAPLs) mobilization in contaminated soils and groundwaters in the climate change context. Intersol 2022, Jun 2022, Lyon, France. ⟨hal-03752664⟩
87 Consultations
0 Téléchargements

Partager

Gmail Facebook X LinkedIn More