Modelling the surface transport and spatio-temporal extent of microplastic pollution in the Southern Ocean and Antarctic waters

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Project Background: The Southern Ocean and Antarctic marine environment are often considered pristine and largely beyond the reach of human impact. However, of increasing concern is the presence of tiny floating plastic fragments (microplastics) found in Antarctic and sub-Antarctic waters and sediments [Waller et al., 2017]. Microplastics can be ingested by keystone filter feeder species such as Antarctic krill, with toxicological effects that can in turn accumulate through the food chain and impact larger predators such as seabirds, seals and whales [Cole et al., 2013; Kaposi et al., 2014; Lusher et al. 2015.]. The deposition of microplastics on the seabed will also likely impact benthic communities. Crucially, however, the extent, quantity, sources and impacts of marine plastics in Antarctica are largely unknown. Recent studies indicate that local sources such as shipping and scientific research stations do not account for recorded concentrations of microplastics indicating an influx of plastic from more remote regions [Waller et al., 2017]. This project will use models and field observations to better understand the sources, dispersal routes and timescales of microplastics that have reached Antarctic waters. Ultimately, this project will help to inform the future governance of polar marine pollution.Project Aims and Methods: The primary aim of this project is to better quantify the sources, pathways and distribution of marine microplastics in Antarctica and the surrounding Southern Ocean. The Southern Ocean acts as a confluence and upwelling zone for water masses from across the globe, and hence likely collects microplastics from far reaching sources. However, the strong circumpolar currents associated with the Southern Ocean can also act as barriers to the southward flux of particles into the Antarctic waters. The difficulty of collecting sufficient temporal and spatially distributed concentrations of microplastics across the Southern Ocean means that ocean models are an essential tool to 'fill in the gaps'. This project will use Lagrangian (i.e. particle tracking) models to map the pathways of microplastics that have reached Antarctic waters from both local and remote sources [e.g. Van Sebille et al. 2015]. In particular, model data will help to assess the role of smaller scale processes such as storms and eddies in facilitating the southward transfer of microplastic across the frontal barriers that encircle the Antarctic continent [Tamzitt et al., 2017; Fraser et al. 2018]. Model data will be initialised and validated by observations of marine microplastic distribution and concentrations collected by the British Antarctic Survey (BAS). Although largely theoretically based, there may be the opportunity for the student to participate in a BAS research cruise to the Southern Ocean to gain experience of fieldwork and microplastic data collection.The student will benefit from interaction and collaboration with the newly-formed Scientific Committee on Antarctic Research (SCAR) action group Plastics in Polar Environment.There will be some flexibility to adjust this PhD project to allow the successful applicant to direct their own research and cater for any specific interests - it will have to stay broadly within the current remit, be aligned with available data and remain within the expertise of project supervisors.