Dynamique, réactivité et écotoxicité des nanoparticules d’oxydes métalliques dans les sols : impact sur les fonctions et la diversité des communautés microbiennes

Abstract : Manufactured metallic nanoparticles (NPs) are emerging pollutants of soils due to their increasing utilization in numerous commercial products (cosmetics, food, paint…). In vitro studies have demonstrated NPs toxicity on microorganisms but data are still scarce on the fate and ecotoxicity of these contaminants in soils. The objective of this thesis was to assess the influence of soil properties on (i) the physicochemical characteristics and the transport of NPs, and (ii) on the NPs toxicity on soil microbial communities, especially on microbial functional groups involved in carbon and nitrogen cycles. This work highlighted that soil properties influenced the aggregation and the surface charges of titanium dioxide NPs (TiO2-NPs) and copper oxide NPs (CuO-NPs). In the six agricultural soils studied, we observed a very low transport of the two NPs in a soil column experiment. We observed a low toxicity of TiO2-NPs for soil microbial communities, except in a silty-clay soil with a high organic matter content. In this soil, microbial activities (soil respiration, nitrification and denitrification) and nitrifier abundances were strongly decreased and archaeal and bacterial community structure were altered after 90 days of exposure. Furthermore in this soil, we observed decreases of nitrification activity, even for very low TiO2-NPs concentrations (0.05 mg kg-1) which were explained by a high sensitivity of ammonia-oxidizing archaea (AOA) involved in this process. Additional studies in soil columns demonstrated that chronic contamination with TiO2-NPs caused more deleterious effects on nitrification than acute contamination
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Marie Simonin. Dynamique, réactivité et écotoxicité des nanoparticules d’oxydes métalliques dans les sols : impact sur les fonctions et la diversité des communautés microbiennes. Ecotoxicologie. Université Claude Bernard - Lyon I, 2015. Français. ⟨NNT : 2015LYO10164⟩. ⟨tel-01272111⟩

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