Journal of Hazardous Materials 283 (2015) 529–535

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Influence of soil properties on the toxicity of TiO2 nanoparticles on carbon mineralization and bacterial abundance Marie Simonin a,b,c,d , Julien P. Guyonnet a,b,c , Jean M.F. Martins d , Morgane Ginot a,b,c , Agnès Richaume a,b,c,∗ a

Université de Lyon, Lyon, France Université Claude Bernard Lyon 1, Villeurbanne, France c CNRS, UMR 5557, Ecologie Microbienne, Université Lyon 1, Villeurbanne, France d UJF-Grenoble/CNRS-INSU/G-INP/IRD, LTHE UMR 5564, Grenoble F-38041, France b

h i g h l i g h t s • • • •

We tested TiO2 -NPs effects on microbial communities in six contrasted soils. In all soils but one, TiO2 -NPs had no impact on microbial communities. A low dose of TiO2 -NPs decreases C-mineralization in a silty-clay soil. TiO2 -NPs toxicity is likely driven by soil pH and organic matter content.

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Article history: Received 16 May 2014 Received in revised form 27 September 2014 Accepted 3 October 2014 Available online 12 October 2014 Keywords: TiO2 nanomaterials Microbial community Microbial ecotoxicology Realistic exposure

a b s t r a c t Information regarding the impact of low concentration of engineered nanoparticles on soil microbial communities is currently limited and the importance of soil characteristics is often neglected in ecological risk assessment. To evaluate the impact of TiO2 nanoparticles (NPs) on soil microbial communities (measured on bacterial abundance and carbon mineralization activity), 6 agricultural soils exhibiting contrasted textures and organic matter contents were exposed for 90 days to a low environmentally relevant concentration or to an accidental spiking of TiO2 -NPs (1 and 500 mg kg−1 dry soil, respectively) in microcosms. In most soils, TiO2 -NPs did not impact the activity and abundance of microbial communities, except in the silty-clay soil (high OM) where C-mineralization was significantly lowered, even with the low NPs concentration. Our results suggest that TiO2 -NPs toxicity does not depend on soil texture but likely on pH and OM content. We characterized TiO2 -NPs aggregation and zeta potential in soil solutions, in order to explain the difference of TiO2 -NPs effects on soil C-mineralization. Zeta potential and aggregation of TiO2 -NPs in the silty-clay (high OM) soil solution lead to a lower stability of TiO2 -NP-aggregates than in the other soils. Further experiments would be necessary to evaluate the relationship between TiO2 -NPs stability and toxicity in the soil. © 2014 Elsevier B.V. All rights reserved.

1. Introduction Titanium dioxide nanoparticles (TiO2 -NPs) are engineered nanomaterials that are commonly used in diverse domains, such as cosmetics, sunscreens, paints, or coatings [1,2]. A large fraction of TiO2 -NPs in commercial products can reach natural ecosystems, especially the soil, which is one of the biggest sink for nanomaterials

∗ Corresponding author at: CNRS, UMR 5557, Ecologie Microbienne, Université Lyon 1, Villeurbanne, France. Tel.: +33 472432650; fax: +33 472431223. E-mail address: [email protected] (A. Richaume). http://dx.doi.org/10.1016/j.jhazmat.2014.10.004 0304-3894/© 2014 Elsevier B.V. All rights reserved.

[3–5]. The major pathways for TiO2 -NPs to enter soil are through agricultural amendments of sewage sludge or after an accidental spill during industrial production [6,7]. The increasing environmental release of TiO2 -NPs raises concerns about the potential effect on soil functioning and consequently on its capacity to fulfill essential ecosystem services. Soils are porous systems consisting in complex structured assemblies of mineral and organic particles combined with liquid and gaseous phases. Soil properties such as clay and organic matter (OM) contents or pH greatly influence the behavior and bioavailability of common pollutants like pesticides, heavy metals or polycyclic aromatic hydrocarbons [8–12]. However, little

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information is available on the influence of soil properties on the aggregation and surface charge of NPs, which will determine their mobility and bioavailability [13–15]. Vittori Antisari et al. [16] demonstrated that metal oxide NPs are localized in small size (2–53 and

Influence of soil properties on the toxicity of TiO₂ nanoparticles on carbon mineralization and bacterial abundance.

Information regarding the impact of low concentration of engineered nanoparticles on soil microbial communities is currently limited and the importanc...
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