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Impact of the soil mineralogy on the contamination and the microbial communities during lab-scale bioremediation of petroleum-contaminated soil

Abstract : Nearly one quarter of the sites requiring a monitoring, invento- ried in the French database BASOL, are impacted by petroleum contamination. During natural attenuation, these organic contami- nations evolve through abiotic and biotic processes as they are known to be sensitive to microbial degradation. In parallel to mineralization, the contamination transformation can cause an accumulation of refractory residual by-products (high molecular weight compounds, polar polyaromatic compounds) through time. Moreover, soil minerals can interact with the contamination and impact degradation processes. They have a role in the sorption of organic molecules, hence affecting their availability towards biota, especially microorganisms. They can (i) catalyze condensation reaction of some molecules, particularly during abiotic oxidation, and (ii) influence the selection of microbial consortia. The aim of this study is to clarify the interactions between the petroleum contamination, the soil minerals and the microorgan- isms. This work focuses especially on (i) elucidating to what extent the selection of microorganism is control by the nature of pollution and/or mineral in soil, and (ii) understanding the impact of mineral phases on petroleum contamination and on soil microorganism evolutions. To achieve this goal, a forest soil impacted by petroleum seepage since several centuries was sampled in the forest of Haguenau (Alsace, France). A batch microbial incubation was carried out in the laboratory according to several modalities: the soil, a mixture of soil and goethite (10%wt), a mixture of soil and Fontainebleau sand (20%wt), a mixture of soil and bentonite (20%wt). Addition- ally, these four modalities were also spiked with 5% wt of crude oil sampled on site. The initial and incubated samples were characterized in term of (i) mineralogy and surface properties, (ii) microbial abundance and structure, and (iii) petroleum composition through molecular and spectroscopic analyses. Additionally the CO2 production was monitored throughout the incubation and enzymatic activities (phosphatase, arylsulfatase...) were determined initially and for three intermediate sampling times. The first results reveal that the mineral phases and the petroleum spiking impacted the CO2 production. Molecular analyses showed that the petroleum spiked soil and soil mixed with sand reached a higher degradation level than the soil mixed with goethite and bentonite. For the latter, the degradation was very limited suggesting either a strong sorption of the hydrocarbons on the bentonite surface leading to lower contaminant availability, or a negative impact of the bentonite on the petroleum degrading microbial communities. In term of microbiology, a first screening showed only slight impact of the incubation on the microbial abundance whatever the modality. Additional data concerning the three studied compartments (mineral, petroleum and microorganisms) that are currently being acquired, will implement these first results.
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Submitted on : Tuesday, March 23, 2021 - 11:44:11 AM
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  • HAL Id : hal-03177579, version 1


Axel Lebreton, Coralie Biache, Catherine Lorgeoux, Aurélie Cébron, Thierry Beguiristain, et al.. Impact of the soil mineralogy on the contamination and the microbial communities during lab-scale bioremediation of petroleum-contaminated soil. Aquaconsoil, May 2019, Anvers, Belgium. ⟨hal-03177579⟩



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