title: Behavior and chronic toxicity of two differently stabilized silver nanoparticles to Daphnia magna.
abstract: While differences in silver nanoparticle (AgNP) colloidal stability, surface potential, or acute aquatic toxicity for differently stabilized AgNP have often been reported, these have rarely been studied in long-term ecotoxicity tests. In the current study, we investigated the chronic toxicity of AgNP to Daphnia magna over a 21-day period with two different stabilizers (citrate and detergent), representative for charge and sterical stabilizers, respectively. This was coupled with a series of short-term experiments, such as mass balance and uptake/depuration testing, to investigate the behavior of both types of AgNP during a typical media exchange period in the D. magna test for chronic toxicity. As expected, the sterically stabilized AgNP was more stable in the test medium, also in the presence of food; however, a higher uptake of silver after 24h exposure of the charge stabilized AgNP was found compared to the detergent-stabilized AgNP (0.046±0.006μgAgμgDW(-1) and 0.023±0.005μgAgμgDW(-1), respectively). In accordance with this, the higher reproductive effects and mortality were found for the charge-stabilized than for the sterically-stabilized silver nanoparticles in 21-d tests for chronic toxicity. LOEC was 19.2μgAgL(-1) for both endpoints for citrate-coated AgNP and >27.5μgAgL(-1) (highest tested concentration for detergent-stabilized AgNP). This indicates a link between uptake and toxicity. The inclusion of additional short-term experiments on uptake and depuration is recommended when longer-term chronic experiments with nanoparticles are conducted.
authors.affiliation: University of Bremen, Center for Environmental Research and Technology, General and Theoretical Ecology, Leobener Str., 28359 Bremen, Germany. Electronic address: yvonne.sakka@uni-bremen.de.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Sakka
authors.affiliation: Technical University of Denmark (DTU), Department of Environmental Engineering, Miljoevej 113, 2800 Kgs., Lyngby, Denmark. Electronic address: lams@env.dtu.dk.
authors.forename: Lars Michael
authors.initials: LM
authors.lastname: Skjolding
authors.affiliation: Technical University of Denmark (DTU), Department of Environmental Engineering, Miljoevej 113, 2800 Kgs., Lyngby, Denmark. Electronic address: aima@env.dtu.dk.
authors.forename: Aiga
authors.initials: A
authors.lastname: Mackevica
authors.affiliation: University of Bremen, Center for Environmental Research and Technology, General and Theoretical Ecology, Leobener Str., 28359 Bremen, Germany. Electronic address: filser@uni-bremen.de.
authors.forename: Juliane
authors.initials: J
authors.lastname: Filser
authors.affiliation: Technical University of Denmark (DTU), Department of Environmental Engineering, Miljoevej 113, 2800 Kgs., Lyngby, Denmark. Electronic address: abau@env.dtu.dk.
authors.forename: Anders
authors.initials: A
authors.lastname: Baun
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D003621:Daphnia / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D013058:Mass Spectrometry; D053768:Metal Nanoparticles / Q000633:toxicity*; D046529:Microscopy, Electron, Transmission; D012834:Silver / Q000032:analysis / Q000737:chemistry*; D036401:Toxicity Tests, Chronic; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D012834:Silver
keywords: Chronic toxicity; D. magna; Silver nanoparticle; Stabilizer effect; Uptake