Article in peer-reviewed journal
October 2016, Scientific Reports 6, Article number: 33882

Merel Kooi, Julia Reisser, Boyan Slat, Francesco F. Ferrari, Moritz S. Schmid, Serena Cunsolo, Roberto Brambini, Kimberly Noble, Lys-Anne Sirks, Theo E. W. Linders, Rosanna I. Schoeneich-Argent and Albert A. Koelmans

  • Publication type: Article in peer-reviewed journal
  • Journal: Scientific Reports 6, Article number: 33882 (2016)
  • Collaborators: Wageningen University & Research (The Netherlands), Université Laval (Canada), Aalborg University (Denmark), Roger Williams University (USA), CABI Europe-Switzerland (Switzerland), University Oldenburg (Germany), IMARES - Institute of Marine Resources & Ecosystem Studies (The Netherlands)
  • DOI: 10.1038/srep33882
  • Submitted: 13.06.2016
  • Accepted: 05.09.2016
  • Published: 10.10.2016


Most studies on buoyant microplastics in the marine environment rely on sea surface sampling. Consequently, microplastic amounts can be underestimated, as turbulence leads to vertical mixing. Models that correct for vertical mixing are based on limited data. In this study we report measurements of the depth profile of buoyant microplastics in the North Atlantic subtropical gyre, from 0 to 5 m depth. Microplastics were separated into size classes (0.5–1.5 and 1.5–5.0 mm) and types (‘fragments’ and ‘lines’), and associated with a sea state. Microplastic concentrations decreased exponentially with depth, with both sea state and particle properties affecting the steepness of the decrease. Concentrations approached zero within 5 m depth, indicating that most buoyant microplastics are present on or near the surface. Plastic rise velocities were also measured, and were found to differ significantly for different sizes and shapes. Our results suggest that (1) surface samplers such as manta trawls underestimate total buoyant microplastic amounts by a factor of 1.04–30.0 and (2) estimations of depth-integrated buoyant plastic concentrations should be done across different particle sizes and types. Our findings can assist with improving buoyant ocean plastic vertical mixing models, mass balance exercises, impact assessments and mitigation strategies.

  • Hydrology, Marine biology, Marine chemistry, Physical oceanography