title: Understanding the fate and biological effects of Ag- and TiO₂-nanoparticles in the environment: The quest for advanced analytics and interdisciplinary concepts.
abstract: Engineered inorganic nanoparticles (EINP) from consumers' products and industrial applications, especially silver and titanium dioxide nanoparticles (NP), are emitted into the aquatic and terrestrial environments in increasing amounts. However, the current knowledge on their environmental fate and biological effects is diverse and renders reliable predictions complicated. This review critically evaluates existing knowledge on colloidal aging mechanisms, biological functioning and transport of Ag NP and TiO2 NP in water and soil and it discusses challenges for concepts, experimental approaches and analytical methods in order to obtain a comprehensive understanding of the processes linking NP fate and effects. Ag NP undergo dissolution and oxidation with Ag2S as a thermodynamically determined endpoint. Nonetheless, Ag NP also undergo colloidal transformations in the nanoparticulate state and may act as carriers for other substances. Ag NP and TiO2 NP can have adverse biological effects on organisms. Whereas Ag NP reveal higher colloidal stability and mobility, the efficiency of NOM as a stabilizing agent is greater towards TiO2 NP than towards Ag NP, and multivalent cations can dominate the colloidal behavior over NOM. Many of the past analytical obstacles have been overcome just recently. Single particle ICP-MS based methods in combination with field flow fractionation techniques and hydrodynamic chromatography have the potential to fill the gaps currently hampering a comprehensive understanding of fate and effects also at a low field relevant concentrations. These analytical developments will allow for mechanistically orientated research and transfer to a larger set of EINP. This includes separating processes driven by NP specific properties and bulk chemical properties, categorization of effect-triggering pathways directing the EINP effects towards specific recipients, and identification of dominant environmental parameters triggering fate and effect of EINP in specific ecosystems (e.g. soil, lake, or riverine systems).
authors.affiliation: Universität Koblenz-Landau, Institute for Environmental Sciences, Group of Environmental and Soil Chemistry, Fortstr. 7, D-76829 Landau, Germany. Electronic address: schaumann@uni-landau.de.
authors.forename: Gabriele E
authors.initials: GE
authors.lastname: Schaumann
authors.affiliation: Universität Koblenz-Landau, Institute for Environmental Sciences, Group of Environmental and Soil Chemistry, Fortstr. 7, D-76829 Landau, Germany. Electronic address: philippe@uni-landau.de.
authors.forename: Allan
authors.initials: A
authors.lastname: Philippe
authors.affiliation: Universität Koblenz-Landau, Institute for Environmental Sciences, Group of Ecotoxicology and Environment, Fortstr. 7, D-76829 Landau, Germany; Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment, Lennart Hjelms väg 9, SE-75007 Uppsala, Sweden. Electronic address: mirco.bundschuh@slu.se.
authors.forename: Mirco
authors.initials: M
authors.lastname: Bundschuh
authors.affiliation: Universität Koblenz-Landau, Institute for Environmental Sciences, Group of Environmental and Soil Chemistry, Fortstr. 7, D-76829 Landau, Germany. Electronic address: metreveli@uni-landau.de.
authors.forename: George
authors.initials: G
authors.lastname: Metreveli
authors.affiliation: Albert-Ludwigs-Universität Freiburg, Institute of Forest Sciences, Chair of Soil Ecology, 79085 Freiburg i.Br., Germany; Berlin University of Technology, Institute of Ecology, Department of Soil Science, Ernst-Reuter-Platz 1, D-10587 Berlin, Germany. Electronic address: sondra.klitzke@tu-berlin.de.
authors.forename: Sondra
authors.initials: S
authors.lastname: Klitzke
authors.affiliation: Universität Koblenz-Landau, Institute for Environmental Sciences, Group of Environmental and Soil Chemistry, Fortstr. 7, D-76829 Landau, Germany. Electronic address: rakcheev@uni-landau.de.
authors.forename: Denis
authors.initials: D
authors.lastname: Rakcheev
authors.affiliation: Universität Koblenz-Landau, Institute for Integrated Natural Sciences, Dept. of Biology, Universitätsstr. 1, D-56070 Koblenz, Germany. Electronic address: alexg@uni-koblenz.de.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Grün
authors.affiliation: Helmholtz Centre for Environmental Research - UFZ, Department of Soil Physics, Theodor-Lieser-Strasse 4, D-06120 Halle, Germany. Electronic address: samuel.kumahor@ufz.de.
authors.forename: Samuel K
authors.initials: SK
authors.lastname: Kumahor
authors.affiliation: Technische Universität München, Institute of Hydrochemistry, Marchioninistr. 17, D-81377 Munich, Germany. Electronic address: melanie.kuehn@tum.de.
authors.forename: Melanie
authors.initials: M
authors.lastname: Kühn
authors.affiliation: Technische Universität München, Institute of Hydrochemistry, Marchioninistr. 17, D-81377 Munich, Germany. Electronic address: tbaumann@tum.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Baumann
authors.affiliation: Albert-Ludwigs-Universität Freiburg, Institute of Forest Sciences, Chair of Soil Ecology, 79085 Freiburg i.Br., Germany. Electronic address: friederike.lang@bodenkunde.uni-freiburg.de.
authors.forename: Friederike
authors.initials: F
authors.lastname: Lang
authors.affiliation: Universität Koblenz-Landau, Institute for Integrated Natural Sciences, Dept. of Biology, Universitätsstr. 1, D-56070 Koblenz, Germany. Electronic address: manz@uni-koblenz.de.
authors.forename: Werner
authors.initials: W
authors.lastname: Manz
authors.affiliation: Universität Koblenz-Landau, Institute for Environmental Sciences, Group of Ecotoxicology and Environment, Fortstr. 7, D-76829 Landau, Germany. Electronic address: schulz@uni-landau.de.
authors.forename: Ralf
authors.initials: R
authors.lastname: Schulz
authors.affiliation: Helmholtz Centre for Environmental Research - UFZ, Department of Soil Physics, Theodor-Lieser-Strasse 4, D-06120 Halle, Germany; Martin-Luther-University Halle-Wittenberg, Institute of Soil Science and Plant Nutrition, Von-Seckendorff-Platz 3, 06120 Halle/Saale, Germany. Electronic address: hans-joerg.vogel@ufz.de.
authors.forename: Hans-Jörg
authors.initials: HJ
authors.lastname: Vogel
mesh_terms: D004785:Environmental Pollutants; D053758:Nanoparticles; D018030:Silver Compounds; D013816:Thermodynamics; D014025:Titanium
chemical_list: D004785:Environmental Pollutants; D018030:Silver Compounds; C009495:titanium dioxide; D014025:Titanium
keywords: Aggregation; Aging; Analytics; Ecotoxicology; Environment; Transport