Chronic dosing of a simulated pond ecosystem in indoor aquatic mesocosms: fate and transport of CeO2nanoparticlesElectronic supplementary information (ESI) available: Physico-chemical characterization of the nanoparticles and the kaolinites, characterization of the water column and sediments of the mesocosms (picoplankton, algae, physico-chemical parameters, and suspended matter), geochemical modeling, biovolume calculations, XANES of Ce in the water column, and HERFD-XAS set-up. See DOI: 10.1039/c5en00092k

Indoor aquatic mesocosms were designed to mimic pond ecosystems contaminated by a continuous point-source discharge of cerium oxide nanoparticles (CeO2-NPs). Bare and citrate-coated CeO2-NPs exhibited different chemical and colloidal behaviors in the aquatic mesocosms. Bare CeO2-NPs were chemically stable but quickly homo-aggregated and settled out of the water column. Citrate-coated NPs both homo- and hetero-aggregated but only after the several days required to degrade the citrate coating. While they were more stable as a colloidal suspension, coated CeO2-NPs dissolved faster due to surface complexation with citrate, which resulted in the release of dissolved Ce into the water column. The different distributions over time between water/sediment or dissolved/particulate forms of Ce controlled the availability of Ce to benthic grazers (mollusk Planorbarius corneus) and planktonic filter feeders (copepod Eudiaptomus vulgaris).