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Impact of the mineralogy on petroleum‐contaminated soil combining mineral and organic geochemistry and microbiology approaches

Abstract : Among soil minerals, clays are particularly known to interact with organic matter and organic contaminants and impact degradation processes. They can (i) sorb the pollutant and reduce their bioavailability (ii) stabilize the contamination through catalysis of condensation reaction and (iii) influence the selection of microbial consortia. The aim of this study is to investigate the role of clay minerals - in comparison with other minerals - in petroleum degradation of a natural forest soil. This work focuses on (i) elucidating to what extent the selection of microorganism and their activity is controlled by the presence of clay or other minerals in soil and/or by the nature of the pollution, and (ii) understanding the impact of clay mineral on petroleum contamination fate. A forest soil, impacted by petroleum seepage for several centuries, where microbial communities are adapted to petroleum contamination, was sampled in the Haguenau forest (Alsace, France). Batch incubation was carried out with the soil, and a series of enriched soil with bentonite (20%wt), Fontainebleau sand (20%wt) and goethite (10%wt), all spiked with petroleum (5%wt) sampled on site. Mineralogy and textural properties, total microbial community and functional population abundance, and petroleum composition were determined for the initial samples and at the end of incubation (62 days). The CO2 production through carbon mineralization was monitored throughout the incubation. The first results revealed that the clay minerals affect microbial activity, as shown by the evolution of CO2 production (Figure 1). Hydrocarbon molecular analyses (GC-MS – GC-FID) showed that soil and soil/sand mixture reached higher degradation level than soil mixed with goethite and bentonite. For the latter, the degradation was very limited suggesting a possible strong sorption of hydrocarbons on bentonite surface leading to lower contaminant availability. The bacterial and fungal abundances (rDNA genes) increased during the experiment for all the conditions. The abundance of genes involved in aromatic compound degradation increased as well for all the modalities except for the soil/bentonite mixture, which tend to support the previous findings. These first results suggest that clay minerals tend to limit the hydrocarbon degradation which could have significant consequences for the remediation of some contaminated soils. However, additional data that are currently being acquired, will implement this first conclusion.
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Submitted on : Tuesday, March 23, 2021 - 11:29:29 AM
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  • HAL Id : hal-03177541, version 1


Axel Lebreton, Coralie Biache, Catherine Lorgeoux, Aurélie Cébron, Thierry Beguiristain, et al.. Impact of the mineralogy on petroleum‐contaminated soil combining mineral and organic geochemistry and microbiology approaches. Euroclay, Jul 2019, Paris, France. ⟨hal-03177541⟩



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