Assessing the fate of micro and nano plastics in freshwaters

High concentrations of plastic debris of micro and nanoscale sizes have been observed in the oceans, and microplastics are increasingly being detected in freshwaters of Europe, North America, and Asia (Eerkes-Medrano et al, 2015). The first organismal studies are finding that freshwater fauna across a range of feeding guilds ingest microplastics. Three possible toxic effects of plastic particles have been recognised: first due to the plastic particles themselves, second to the release of persistent organic pollutant adsorbed to the plastics, and third to the leaching of additives of the plastics (Bouwmeester et al; 2015). Given their highly specific composition, and persistence in the environment, micro and nano plastics have been proposed as efficient 'natural' tracers, with the idea that certain plastics could be attributed to specific flow paths.
The current project aims to draw together cross-disciplinary expertise from across the School of Geography, Earth and Environmental Science (from two research hotspots), regarding detection and characterisation of micro and nanoparticles in the environment, hydrological cycles and flow of microplastics from source to sinks, ecosystems impacts, including uptake by and toxicity to Daphnia magna (representing the freshwater column), or C. elegans as a sediment feeder. Factors considered will include physical damage to organisms that ingest them, and potential for chemical transfer of other toxicants/pollutants present in freshwater systems (e.g. pesticides, fertilisers etc.) and possibly (depending on types of microplastics sampled) the potential for release from microplastics of plasticisers or other toxic components.
The combined experimental and modelling approach will also important insights into strategies for reducing the ecosystems impacts of microplastics through selection of composition to facilitate environmental degradation / capture in wastewater treatment plants or tailoring of surface to reduce "stickiness" of other physical aspects of interactions with organisms.
Methodology:
Sample collection, fractionation (sieving, separation) and identification of microplastics from UK rivers / canals. Analysis of composition of the separated microplastic types by range of chemical analysis approaches, including FTIR, Raman spectroscopy, thermogravimetric analysis, pyrolytic GC-MS etc.
Stability and interactions in freshwater will be assesssed using light scattering, Quartz crystal microbalance, column chromatorgraphy etc. Inpacts on test species (e.g. daphnia) will be assessed via modified OECD tests for mobility and reproduction, supplemented with confocal microscopy and Transmission Electron Microscopy analysis to determine localisation of microparticles (stuck on surface, in gut, internalised into organism). Modelling of micro and nanoplastic fate in the environment will be undertaken using SimpleBox adaptions for particles and via parameters such as Deybe screening lengths.