This multidisciplinary study aims to assess how different geological and oceanographic processes control the deposition of sediment and microplastics, and their control or influence on the benthic organisms living within deep marine sediments. Three key objectives will be addressed across a study area in the NE Atlantic: (1) Characterise the facies, sediment texture and benthic assemblages across different depositional environments and energy regimes influenced by alongslope ocean currents, downslope gravity flows and pelagic settling; (2) Identify the depositional environment control on microplastic accumulation; and (3) Assess the influence of microplastics on benthic organisms and their activities.
99% of the global marine plastic budget is unaccounted for in known surface waste patches (Koelmans et al. 2017). It is therefore thought that large volumes of waste are accumulating in the deep ocean. However, little is known of the source to sink cycle of plastics in deep marine settings. Recent research shows sediments deposited by deep ocean currents - named contourites (Rebesco et al. 2014) - are potential hot spots for deposition (Kane et al. 2020) and it is hypothesised that contourite sediment drifts are the ultimate sink of microplastics in the ocean. Contourites are characterized by heavily bioturbated sediment, owing to the diverse benthos feeding off the nutrient-rich ocean currents that control their deposition. Burrowing organisms, combined with the elevated sediment accumulation rates typical of contouritic sediments provides an opportunity for rapid sequestration of microplastics into the subsurface.
This project will use earth and marine science methods to test the control of depositional environment on microplastic accumulation and benthos in the deep ocean. The results will inform modelling of plastic distribution in the ocean basins and address the significant missing portion of the global plastic budget. It will also highlight if the influx of these artificial materials into the deep ocean are modifying benthic assemblages, and if so, which particle types are most damaging.
Research will be completed in the University of Aberdeen, with partners in Queens University Belfast. Sediment samples will be analysed for: (1) composition (using XRF and smear slide analysis); (2) textural characteristics (sediment grainsize distribution using laser particle analyser); (3) sediment microplastic fraction and composition; and (4) benthic foraminifera assemblages. Sample analysis will be supplemented by core logging to determine the environment of deposition and intensity of sediment reworking and bioturbation. Results will be analysed using multivariant statistical methods and will be integrated into seabed geological mapping to define the present-day environment of deposition in the study area.
This multi-disciplinary project offers a unique opportunity to link modern and ancient systems in a high-impact research area. As such we are seeking a PhD candidate with excellent analytical and numeracy skills who works with a strong attention to detail. Previous experience in lab techniques is desirable. Training in analytical sedimentology and microbiology lab techniques will be provided in Aberdeen and Belfast. Multiple data collection opportunities will be provided through visiting national and international core repositories, and potential ship-board time. As such the PhD candidate must be willing to travel.
More project details are available here: https://www.quadrat.ac.uk/quadrat-projects/
How to apply: https://www.quadrat.ac.uk/how-to-apply/
Continue with Facebook
