title: Fate of engineered cerium oxide nanoparticles in an aquatic environment and their toxicity toward 14 ciliated protist species.
abstract: The potential environmental impacts of engineered cerium oxide nanoparticles (CeO2 NPs) on aquatic organisms have remained largely unknown. Therefore, the laboratory study featured herein was performed to determine the fate of CeO2 NPs in an aquatic environment and their toxicity towards 14 different ciliated protist species at a specified population level. An investigation of 48 h aggregation kinetics in the Dryl's solution showed the CeO2 NPs to be relatively stable. The pH values in three test medium were too far away from PZC, which explained the stability of CeO2 NPs. CeO2 NPs generally elicited more toxicity with increasing NP concentration, following certain dose-response relationships. Nano-CeO2 resulted in greater toxicity in a particle state than when added as bulk material. LC50 values showed a negative correlation with the surface-to-volume ratio for these protists, suggesting that surface adsorption of CeO2 NPs might contribute to the observed toxicity. Additionally, acute toxic responses of 14 ciliated protist species to CeO2 NPs were not significantly phylogenetically conserved. The results of these observations provide a better insight into the potential risks of CeO2 NPs in an aquatic environment.
authors.affiliation: State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China; School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta 30332, USA; School of Biology, Georgia Institute of Technology, Atlanta 30332, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: School of Biology, Georgia Institute of Technology, Atlanta 30332, USA.
authors.forename: Zhichao
authors.initials: Z
authors.lastname: Pu
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta 30332, USA.
authors.forename: Songyan
authors.initials: S
authors.lastname: Du
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta 30332, USA. Electronic address: yongsheng.chen@ce.gatech.edu.
authors.forename: Yongsheng
authors.initials: Y
authors.lastname: Chen
authors.affiliation: School of Biology, Georgia Institute of Technology, Atlanta 30332, USA. Electronic address: lin.jiang@biology.gatech.edu.
authors.forename: Lin
authors.initials: L
authors.lastname: Jiang
mesh_terms: D000327:Adsorption; D002563:Cerium / Q000737:chemistry / Q000633:toxicity*; D016798:Ciliophora / Q000187:drug effects*; D017753:Ecosystem; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D013045:Species Specificity; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D002563:Cerium; C030583:ceric oxide
keywords: Acute toxicity; CeO(2) NPs; Ciliated protist; Environmental fate; Phylogenetic conservatism