Article in peer-reviewed journal
February 2015, Biogeosciences 12

Julia Reisser, Boyan Slat, Kim Noble, K. du Plessis, Meredith Epp, Maira Proietti, Jan de Sonneville, Thomas Becker and Charitha Pattiaratchi

  • Publication type: Article in peer-reviewed journal
  • Journal: Biogeosciences 12, 1249-1256 (2015)
  • Collaborators: University of Western Australia (Australia), Roger Williams University (USA), Pangaea Exploration (USA), Universidade Federal do Rio Grande (Brazil)
  • DOI: 10.5194/bg-12-1249-2015
  • Submitted: 31.10.2014
  • Accepted: 16.02.2015
  • Published: 26.02.2015


Millimetre-sized plastics are numerically abundant and widespread across the world’s ocean surface. These buoyant macroscopic particles can be mixed within the upper water column by turbulent transport. Models indicate that the largest decrease in their concentration occurs within the first few metres of water, where in situ observations are very scarce. In order to investigate the depth profile and physical properties of buoyant plastic debris, we used a new type of multi-level trawl at 12 sites within the North Atlantic subtropical gyre to sample from the air–seawater interface to a depth of 5 m, at 0.5 m intervals. Our results show that plastic concentrations drop exponentially with water depth, and decay rates decrease with increasing Beaufort number. Furthermore, smaller pieces presented lower rise velocities and were more susceptible to vertical transport. This resulted in higher depth decays of plastic mass concentration (milligrams m−3 ) than numerical concentration (pieces m−3 ). Further multilevel sampling of plastics will improve our ability to predict at-sea plastic load, size distribution, drifting pattern, and impact on marine species and habitats.

  • Marine debris, Vertical distribution