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The shape and speciation of Ag nanoparticles drive their impacts on organisms in a lotic ecosystem

Auffan M., Santaella C., Brousset L., Tella M., Morel E., Ortet P., Barakat M., Chaneac C., Issartel J., Angeletti B., Levard C., Hazemann J.L., Wiesner M., Rose J., Thiery A., Bottero J.Y.. 2020. Environmental Science. Nano, 7 (10) : p. 3167-3177.

DOI: 10.1039/d0en00442a

Silver nanomaterials with different shapes (spheres, plates, wires, rods, cubes) are valued by industries and scientists for their shape-dependent properties which make them useful for diverse applications. In a safer-by-design perspective, controlling the shape of Ag nanomaterials could be an option to increase their properties while lowering either their hazard or their exposure potentials. Nine indoor aquatic mesocosms reproducing a lotic ecosystem were contaminated with chronic low-level additions of Ag nanospheres (Sp-Ag) and nanoplates (Pl-Ag) for a month. A shape-dependent impact under such environmentally relevant exposure conditions was observed. Pl-Ag induced a moderate oxidative stress in adult Gammarus fossarum (after molting) and a hormesis effect on planktonic microbial communities, while Sp-Ag had no effect. In an environmental risk perspective, our results highlight which ecological niches of a lotic ecosystem would be more impacted by Pl-Ag: (i) >72% of the total Ag was found fully sulfidized in surficial sediment and had only a moderate impact on benthic macro-organisms, (ii) only 11% to 15% of the Ag remained in the water column after 1 month, but Ag was under a more reactive speciation that impacts the planktonic community.

Mots-clés : nanomaterials [en]; argent; plancton; impact sur l'environnement; bioaccumulation; milieu lotique; stress oxydatif; gammarus fossarum; mésocosme

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