Preprints
https://doi.org/10.5194/os-2020-95
https://doi.org/10.5194/os-2020-95

  19 Oct 2020

19 Oct 2020

Review status: a revised version of this preprint was accepted for the journal OS and is expected to appear here in due course.

Sinking microplastics in the water column: simulations in the Mediterranean Sea

Rebeca de la Fuente1, Gábor Drótos1,2, Emilio Hernández García1, Cristóbal López1, and Erik van Sebille3,4 Rebeca de la Fuente et al.
  • 1IFISC (CSIC-UIB), Campus Universitat de les Illes Balears, Palma de Mallorca, Spain
  • 2MTA–ELTE Theoretical Physics Research Group, Budapest, Hungary
  • 3Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, the Netherlands
  • 4Centre for Complex Systems Studies, Utrecht University, Utrecht, the Netherlands

Abstract. We study the vertical dispersion and distribution of negatively buoyant rigid microplastics within a realistic circulation model of the Mediterranean sea. We first propose an equation describing their idealized dynamics. In that framework, we evaluate the importance of some relevant physical effects: inertia, Coriolis force, small-scale turbulence and variable seawater density, and bound the relative error of simplifying the dynamics to a constant sinking velocity added to a large-scale velocity field. We then calculate the amount and vertical distribution of microplastic particles on the water column of the open ocean if their release from the sea surface is continuous at rates compatible with observations in the Mediterranean. The vertical distribution is found to be almost uniform with depth for the majority of our parameter range. Transient distributions from flash releases reveal a non-Gaussian character of the dispersion and various diffusion laws, both normal and anomalous. The origin of these behaviors is explored in terms of horizontal and vertical flow organization.

Rebeca de la Fuente et al.

 
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Status: closed
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Rebeca de la Fuente et al.

Rebeca de la Fuente et al.

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Short summary
Plastic pollution is a major environmental issue affecting the world’s oceans. The amount of floating and sedimented pieces has been quantified by several studies. But their abundance in the water column remains mostly unknown. As a step to fill this gap we model the dynamics of a particular type of particles, rigid microplastics sinking rapidly in open sea. We find that they represent a small but appreciable fraction of the total sea plastic, and discuss characteristics of their sinking motion.