title: The chronic toxicity of CuO nanoparticles and copper salt to Daphnia magna.
abstract: In this study, the effects of CuO nanoparticles and CuCl2·2H2O were tested on Daphnia magna under chronic exposure scenarios. During a 21-day exposure to the nanoparticles and salt, the reproduction was followed by a daily count of the number of offspring. After the exposure, the adult Daphnia length and uptake of copper was measured. The dissolved, nanoparticle and aggregated fractions were distinguished in the exposure medium. The results showed that only a small fraction of the nanoparticles dissolved, while the majority of the particles formed large aggregates (>450 nm). The dissolved fraction of the nanoparticles corresponded with the dissolved fraction of the copper salt. The effects of the nanoparticles (reproduction EC10: 0.546 mg Cu/l, EC20: 0.693 mg Cu/l, EC50: 1.041 mg Cu/l) on reproduction and length were much lower than the effects of the copper salts (reproduction EC10: 0.017 mg Cu/l, EC20: 0.019 mg Cu/l, EC50: 0.022 mg Cu/l). Based upon total body analysis, the Daphnia copper concentration appeared much higher when exposed to the nanoparticles than when exposed to the salt. These combined results indicate that the toxicity of CuO nanoparticles to D. magna is caused by copper ions formed during dissolution of the nanoparticles in the exposure medium.
authors.affiliation: Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Antwerp, Belgium. Electronic address: nathalieadam12@gmail.com.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Adam
authors.affiliation: School of Chemistry, University of Leeds, Leeds, UK.
authors.forename: Alexander
authors.initials: A
authors.lastname: Vakurov
authors.affiliation: Physiology and Biochemistry of Domestic Animals, Department of Veterinary Sciences, University of Antwerp, Antwerp, Belgium.
authors.forename: Dries
authors.initials: D
authors.lastname: Knapen
authors.affiliation: Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Antwerp, Belgium.
authors.forename: Ronny
authors.initials: R
authors.lastname: Blust
mesh_terms: D000818:Animals; D003300:Copper / Q000633:toxicity*; D003621:Daphnia; D053768:Metal Nanoparticles / Q000633:toxicity*; D036401:Toxicity Tests, Chronic; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D003300:Copper; C029892:cupric chloride; C030973:cupric oxide
keywords: Aquatic; Copper; Length; Reproduction; Uptake