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Mobilization and transfer of PAC (Polycyclic Aromatic Compounds): laboratory and lysimeter column experiments

Abstract : In industrial sites historically contaminated by coal-tar (abandoned coking and manufactured-gas plants), other families of organic pollutants than the 16 PAHs (polycyclic aromatic hydrocarbons) classified by the US-EPA can occur and induce potential risk for groundwater resources. Polar PACs (polycyclic aromatic compounds), especially oxygenated PACs (O-PACs), are present in the initial pollution and can also be generated over time. Their aqueous solubility is much greater than those of the PAHs. For these reasons, we need to increase our knowledge on polar PACs in order to better predict their behavior and the potential on-site risk. Two different column experiments were carried out on coking plant soils under saturated (laboratory scale) and unsaturated (lysimeter column on the GISFI experimental station) conditions. On the laboratory scale, different conditions were applied on two different columns: a column with raw coking plant soil and a column with the same soil previously preheated (100°C) under inert atmosphere in order to increase the availability of the contaminants. Different nature (ionic strength, organic matter concentration) of the percolating solutions as well as the flow of the solution were tested in order to evaluate consequences on PAC mobilization. On the field scale (lysimetric column), leaching tests were performed on a lysimeter column (2 m3) filled with a contaminated soil sampled on a former coking plant site. An artificial rain was applied during 4 consecutive days (6 hours per day at 10L/h) twice. The solutions were collected at the bottom of the lysimeter (percolate) as well as at several depths of the column (porous candles). Our works confirm a preferential release of polar PACs compared with PAHs. Polar PACs and low molecular weight PAHs (LMW-PAHs) are mainly released according to a coal-tar dissolution mechanism (Raoult’s law). In the case of laboratory column tests, satisfactory predictions are obtained for polar PAC release when the pollution is “fresh” (available), it is not the case for the raw soil, suggesting that availability is a major parameter that needs to be taken into account for historical contamination impacted by aging. Leaching tests performed on the lysimeter column confirm a release of PACs according to a coal-tar dissolution mechanism, although PAC concentrations are much lower compared to those predicted by the Raoult’s law. Whatever the experimental scale (laboratory or lysimeter columns), a clear influence of the biological compartment has been evidenced. Once the PAHs and polar PACs are dissolved into water, they are highly biodegraded.
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https://hal.univ-lorraine.fr/hal-03178125
Contributor : Pierre Faure <>
Submitted on : Tuesday, March 23, 2021 - 3:35:46 PM
Last modification on : Wednesday, March 24, 2021 - 3:31:04 AM

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  • HAL Id : hal-03178125, version 1

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Marine Boulangé, Lucie Maurice, Catherine Lorgeoux, Coralie Biache, Noële Enjelvin, et al.. Mobilization and transfer of PAC (Polycyclic Aromatic Compounds): laboratory and lysimeter column experiments. TERENO International Conference, Oct 2018, Berlin, Germany. ⟨hal-03178125⟩

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