A review of the properties and processes determining the fate of engineered nanomaterials in the aquatic environment

Proper understanding of the basic processes and specific properties of engineered nanomaterials (NMs) that modify the fate and effects of NMs is crucial for NM-tailored risk assessment. This in turn requires developers of NMs and for regulators to consider the most important parameters governing the properties, behaviour and toxicity of NMs. As fate and effect studies are commonly performed in laboratory settings, mimicking to a varying extent realistic exposure conditions, it is important to be able to extrapolate results of fate and effect studies in synthetic media to realistic environmental conditions. This requires detailed understanding of the processes controlling the fate and behaviour of NMs in terrestrial and aquatic media, as dependent on the composition of the medium. It is the aim of this contribution to provide background reading to the NM and media specific properties and processes that affect the fate and behaviour of NMs in aquatic environments, focussing on the specific properties of NMs that modulate the interactions in the aquatic environment. A general introduction on the dominant fate determining processes of NMs is supplemented by case studies on specific classes of NMs: metal NMs, stable oxides, iron oxides, and carbon nanotubes. Based upon the synthesis of the current knowledge base towards essential data and information needs, the review provides a description of the particle specific properties and the water characteristics that need monitoring in order to allow for future quantification and extrapolation of fate and behaviour properties of NMs in freshwater compartments of varying composition.