BEHAVIOUR AND UPTAKE OF ENGINEERED GOLD NANOP ARTICLES IN AQUATIC SYSTEMS

Nanotechnology is a rapidly growing industry of global economic importance. However, there is concern that the unique properties of engineered nanoparticles (ENPs) which can make them useful to society could mean that they pose a risk to the natural environment. There are still many uncertainties around the behaviour of ENPs in aquatic systems, their capacity to be taken up by aquatic organisms, and their potential toxic effects. This study therefore used four different surface functionalised gold (Au) nanoparticles as exemplars and explored their behaviour in various aquatic systems and their uptake into aquatic organisms. Studies into the behaviour of the study ENPs in standardized ecotoxicity test media showed that the particles exhibit very different aggregation behaviour depending on the test media type, the chemical composition of the test media and surface capping of the nanoparticles. Based on the results of the aggregation studies in a range of natural waters, a series of methods to predict size of Au particles in different water chemistries were developed. Results showed that there would likely be big differences in the aggregation of the different Au nanoparticle types in UK water types which implies that aggregation of ENPs will vary widely across surface waters. The uptake of the four Au nanoparticles into the aquatic invertebrate, Gammarous pulex, did not show obvious relationship between the aggregation state in a treatment and uptake suggesting that the widely accepted assumption that ENP uptake is related to particle size does not hold for the range of aggregation states studied. The results of this thesis showed that the degree of aggregation of ENPs and uptake into aquatic organisms would vary depending on the surface functionalisation of the ENPs and water chemistry. The results imply that aggregation of ENPs will vary widely across surface waters which make assessment of risks a challenge. Additionally, the uptake data indicate that factors other than particle size determine uptake of ENPs into organisms. Therefore, it may be necessary to develop new paradigms and models for risk assessment of ENPs.