| Summary: | The potential environmental impacts of engineered nanomaterials (ENMs) have received increased attention over the last decades. While the benefits of the development and use of ENMs are numerous (e.g., improved medical diagnostics, energy saving, improved environmental monitoring and remediation), there is also a risk of environmental release and potential negative effects to biota. Due to the well-known antibacterial properties of silver, Ag ENMs are amongst the most frequently used ENMs on the market and can be found in, for example, medical applications (e.g., wound dressings, surface coatings of medical devices) and consumer products (e.g., cosmetics, cloths, cleaning agents, and food additives). Silver is known to be highly toxic to aquatic organisms, and the toxicity is usually ascribed to the dissolved species of Ag. The toxicity of Ag ENMs has been extensively studied, however, linking the observed toxicity to exposure characteristics is not always possible due the lack of exposure characterization. Given the tendency of ENMs to aggregate and be removed from the water column by sorption to organisms and sediments, which may in turn be taken up by sediment dwelling organisms, exposure routes to aquatic organisms can include both waterborne and dietary sources. The overarching aim of this PhD research project has been to increase the understanding of the ways in which nanoparticle properties, and in turn their behaviour in toxicity testing media, influence accumulation and toxicity. To explore these issues, a range of experiments involving four different species (Caenorhabditis elegans, Raphidocelis subcapitata, Salmo salar and Salmo trutta) have been designed to test four interlinked hypothesis: 1. Changes in Ag ion and Ag nanoparticle speciation will cause a time dependent change in the nanoparticle/colloidal fraction in test media exposure solutions. 2. Variation in the size fractions of Ag ion and Ag nanoparticles in test media will result in different bioavailability and bioaccumulation in test ...
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