EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Microplastic transport, deposition and burial in seafloor sediments by turbidity currents

Florian Pohl1, Joris Eggenhuisen2, Ian Kane3, and Michael Clare4
Florian Pohl et al.
  • 1Department of Earth Sciences, Durham University, United Kingdom (
  • 2Faculty of Geosciences, Utrecht University, The Netherlands
  • 3School of Earth and Environmental Sciences, University of Manchester, United Kingdom
  • 4National Oceanography Centre, University of Southampton Waterfront Campus, United Kingdom

Plastic pollution of the world’s oceans represents a threat to marine eco-systems and human health and has come under increasing scrutiny from the general public. Today the global input of plastic waste into the oceans is in the order of 10 million tons per year and predicted to rise by an order of magnitude by 2025; much of this plastic ends up on the seafloor. Plastics, and microplastics, are known to be concentrated in submarine canyons due to their proximity to terrestrial plastic sources, i.e. rivers. Plastics are transported in canyons by turbidity currents, mixtures of sediment and water which flow down-canyon due to their density; these flows can also ‘flush’ canyons, eroding and entraining the sediment lining the canyon walls and bottom. A single turbidity current can last for weeks and transport more sediment than the annual flux of all terrestrial rivers combined. Although it is known that these flows play a critical role in delivering terrestrial sediment and organic carbon to the seafloor, their ability to transport and bury plastics is poorly-understood. Using flume experiments we investigate turbidity currents as agents for the transport and burial of microplastic fragments and fibers. Microplastic fragments are focused at the flow base, whereas fibers are more homogeneously distributed throughout the flow. Surprisingly though, the resultant deposits show the opposite trend with fibers having a higher concentration that fragments. We explain this observation with a depositional mechanism whereby fibers are dragged out of suspension by settling sand grains, are trapped in the aggrading sediment bed and are buried in the deposits. Conversely, fragments may remain suspended in the flow and are less likely to be trapped on the bed. Our results suggest that turbidity currents can transport microplastics over long distances across the ocean floor, and that turbidity currents potentially distribute and bury large quantities of microplastics in seafloor sediments.

How to cite: Pohl, F., Eggenhuisen, J., Kane, I., and Clare, M.: Microplastic transport, deposition and burial in seafloor sediments by turbidity currents, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2303,, 2020