PhD: Mixing in turbidity currents in experiments and submarine canyons

The Department of Earth Sciences is looking for a highly motivated PhD candidate with an MSc background in Earth Sciences, Civil or Hydraulic Engineering, or other appropriate fields. You will work on the project: DEEP-FLUX: Journey of low-density particles to the DEEP ocean floor – terrestrial organic carbon and microplastics FLUX through submarine canyons.

Your job
More than 10,000 submarine canyons connect the continents to the deep ocean. These canyons are the conduits for transport of land-derived materials to the ocean floor in avalanche-like events called turbidity currents. Turbidity currents transport enormous amounts of sediment and Particulate Organic Carbon (POC) and bury this in deposits below the ocean floor. They additionally convey abundant nutrients and oxygenated water masses, which together with the POC (as food) support conditions for abundant life at unexpected depths in the absence of light for photosynthesis. Submarine canyons are also called the ‘human connection to the deep sea (Dissanayaka et al., 2023)’. Unfortunately, this connection brings land-derived pollutants (microplastics, pesticides, pharmaceuticals) into the very heart of these ecodiverse hotspots, making them vulnerable to far-field human interference. While this general knowledge is now firmly established, the processes of transport and burial during turbidity current events remain poorly understood.

The DEEP-FLUX project aims to establish a new physical framework for quantifying fluxes of POC and microplastics from land to the ocean floor. The project team will eventually consist of 4 PhD candidates and the PI (Joris Eggenhuisen). Together they will:

1. perform scaled-down laboratory experiments that will reveal the physical mechanisms of transport and burial of microplastics and POC in turbidity currents down submarine canyons;
2. incorporate these mechanisms into an existing computer model for sediment flux through submarine canyons; and
3. validate the model on monitored submarine canyons.

The responsibility of the PhD position advertised here will mainly involve experiments on mixing in turbidity currents, and experimental tests of turbulent diffusion characteristics of microplastics and POC.

Training
A personalised training programme will be set up reflecting your training needs and career objectives. About 20% of your time will be dedicated to this training component, which includes following courses and/or workshops (some of which are mandatory), as well as training on the job in assisting in the bachelor’s and master’s degrees programmes of the department at Utrecht University.