title: Addressing the complexity of water chemistry in environmental fate modeling for engineered nanoparticles.
abstract: Engineered nanoparticle (ENP) fate models developed to date - aimed at predicting ENP concentration in the aqueous environment - have limited applicability because they employ constant environmental conditions along the modeled system or a highly specific environmental representation; both approaches do not show the effects of spatial and/or temporal variability. To address this conceptual gap, we developed a novel modeling strategy that: 1) incorporates spatial variability in environmental conditions in an existing ENP fate model; and 2) analyzes the effect of a wide range of randomly sampled environmental conditions (representing variations in water chemistry). This approach was employed to investigate the transport of nano-TiO2 in the Lower Rhône River (France) under numerous sets of environmental conditions. The predicted spatial concentration profiles of nano-TiO2 were then grouped according to their similarity by using cluster analysis. The analysis resulted in a small number of clusters representing groups of spatial concentration profiles. All clusters show nano-TiO2 accumulation in the sediment layer, supporting results from previous studies. Analysis of the characteristic features of each cluster demonstrated a strong association between the water conditions in regions close to the ENP emission source and the cluster membership of the corresponding spatial concentration profiles. In particular, water compositions favoring heteroaggregation between the ENPs and suspended particulate matter resulted in clusters of low variability. These conditions are, therefore, reliable predictors of the eventual fate of the modeled ENPs. The conclusions from this study are also valid for ENP fate in other large river systems. Our results, therefore, shift the focus of future modeling and experimental research of ENP environmental fate to the water characteristic in regions near the expected ENP emission sources. Under conditions favoring heteroaggregation in these regions, the fate of the ENPs can be readily predicted.
authors: Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich, Switzerland.
authors: Nicole
authors: N
authors: Sani-Kast
authors: Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich, Switzerland; Institute for Sustainable and Environmental Chemistry, Leuphana University Lüneburg, D-21335 Lüneburg, Germany. Electronic address: scheringer@chem.ethz.ch.
authors: Martin
authors: M
authors: Scheringer
authors: Aix-Marseille Université, CNRS, IRD, CEREGE UMR 7330, 13545 Aix-en-Provence, France; International Consortium for the Environmental Implications of Nanotechnology, iCEINT, Aix-en-Provence, France.
authors: Danielle
authors: D
authors: Slomberg
authors: Aix-Marseille Université, CNRS, IRD, CEREGE UMR 7330, 13545 Aix-en-Provence, France; International Consortium for the Environmental Implications of Nanotechnology, iCEINT, Aix-en-Provence, France.
authors: Jérôme
authors: J
authors: Labille
authors: Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich, Switzerland.
authors: Antonia
authors: A
authors: Praetorius
authors: BRGM, 3 Avenue C. Guillemin, BP 36009, 45060 Orléans, France.
authors: Patrick
authors: P
authors: Ollivier
authors: Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich, Switzerland.
authors: Konrad
authors: K
authors: Hungerbühler
mesh_terms: D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis*; D005602:France; D008956:Models, Chemical; D053758:Nanoparticles / Q000032:analysis*
chemical_list: D004785:Environmental Pollutants
keywords: Engineered nanoparticles; Environmental fate modeling; Environmental variability; Nanoparticle fate assessment; River systems; TiO(2)