title: Effects of silver nanoparticle properties, media pH and dissolved organic matter on toxicity to Daphnia magna.
abstract: Studies assessing the acute and chronic toxicity of silver nanoparticle (nAg) materials rarely consider potential implications of environmental variables. In order to increase our understanding in this respect, we investigated the acute and chronic effects of various nAg materials on Daphnia magna. Thereby, different nanoparticle size classes with a citrate coating (20-, ~30-, 60- as well as 100-nm nAg) and one size class without any coating (140 nm) were tested, considering at the same time two pH levels (6.5 and 8.0) as well as the absence or presence of dissolved organic matter (DOM; <0.1 or 8.0 mg total organic carbon/L). Results display a reduced toxicity of nAg in media with higher pH and the presence of DOM as well as increasing initial particle size, if similarly coated. This suggests that the associated fraction of Ag species <2 nm (including Ag(+)) is driving the nAg toxicity. This hypothesis is supported by normalizing the 48-h EC50-values to Ag species <2 nm, which displays comparable toxicity estimates for the majority of the nAg materials assessed. It may therefore be concluded that a combination of both the particle characteristics, i.e. its initial size and surface coating, and environmental factors trigger the toxicity of ion-releasing nanoparticles.
authors.affiliation: Institute for Environmental Sciences, Group of Ecotoxicology & Environment, University of Koblenz-Landau, Fortstrasse 7, 76829 Landau, Germany. Electronic address: seitz-f@uni-landau.de.
authors.forename: Frank
authors.initials: F
authors.lastname: Seitz
authors.affiliation: Institute for Environmental Sciences, Group of Ecotoxicology & Environment, University of Koblenz-Landau, Fortstrasse 7, 76829 Landau, Germany.
authors.forename: Ricki R
authors.initials: RR
authors.lastname: Rosenfeldt
authors.affiliation: Institute for Environmental Sciences, Group of Ecotoxicology & Environment, University of Koblenz-Landau, Fortstrasse 7, 76829 Landau, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Storm
authors.affiliation: Institute for Environmental Sciences, Group of Environmental and Soil Chemistry, University of Koblenz-Landau, Fortstrasse 7, 76829 Landau, Germany.
authors.forename: George
authors.initials: G
authors.lastname: Metreveli
authors.affiliation: Institute for Environmental Sciences, Group of Environmental and Soil Chemistry, University of Koblenz-Landau, Fortstrasse 7, 76829 Landau, Germany.
authors.forename: Gabriele E
authors.initials: GE
authors.lastname: Schaumann
authors.affiliation: Institute for Environmental Sciences, Group of Ecotoxicology & Environment, University of Koblenz-Landau, Fortstrasse 7, 76829 Landau, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Schulz
authors.affiliation: Institute for Environmental Sciences, Group of Ecotoxicology & Environment, University of Koblenz-Landau, Fortstrasse 7, 76829 Landau, Germany; Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Lennart Hjelms Väg 9, 75007 Uppsala, Sweden.
authors.forename: Mirco
authors.initials: M
authors.lastname: Bundschuh
mesh_terms: D000818:Animals; D019343:Citric Acid / Q000737:chemistry / Q000633:toxicity; D003621:Daphnia / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000633:toxicity*; D009930:Organic Chemicals / Q000633:toxicity*; D010316:Particle Size; D012834:Silver / Q000633:toxicity*; D018030:Silver Compounds / Q000737:chemistry / Q000633:toxicity; D023382:Toxicity Tests, Acute; D036401:Toxicity Tests, Chronic; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D009930:Organic Chemicals; D018030:Silver Compounds; D014874:Water Pollutants, Chemical; D019343:Citric Acid; D012834:Silver
keywords: Acute toxicity; Crustacean; Environmental conditions; Nanomaterial; Silver