Scientific Publications - The Ocean Cleanup

At The Ocean Cleanup we face the unique challenge that we don’t only have to develop technology to solve a problem, but at the same time also have to work on understanding the problem itself. Understanding the properties of ocean plastic pollution is critical in developing efficient cleanup systems, determining optimal deployment locations and creating suitable recycling processes.

Collaborations between our in-house research team and various scientific institutions have so far resulted in the following publications:

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Featured publications

Evidence that the Great Pacific Garbage Patch is Rapidly Accumulating Plastic

Article in peer reviewed journal
March 2018, Scientific Reports

Laurent CM Lebreton, Boyan Slat, Francesco Ferrari, Bruno Sainte-Rose, Jen Aitken, Bob Marthouse, Sara Hajbane, Serena Cunsolo, Anna Schwarz, Aurore Levivier, Kim Noble, Pavla Debeljak, Hanna Maral, Rosanna Schoeneich-Argent, Roberto Brambini and Julia Reisser
- Publication type: Article in peer-reviewed journal
- Journal: Scientific Reports
- Collaborators: The Ocean Cleanup Foundation (NL), The Modelling House (NZ), Teledyne Optech (USA), School of Civil, Engineering and Surveying, Faculty of Technology, University of Portsmouth (UK), Department of Biology, Marine Biology and Environmental Science, Roger Williams University (USA), Laboratoire d'Océanographie Microbienne (LOMIC), Sorbonne Universités, Paris (FR), Department of Civil, Geo and Environmental Engineering, Technical University Munich, (DE), ICBM-Terramare, Carl von Ossietzky University Oldenburg, (DE), Civil Engineering Department, Aalborg University, (DK)
- DOI: 10.1038/s41598-018-22939-w
- Submitted: 17.10.2017
- Accepted: 05.03.2018
- Published: 22.03.2018
Abstract

Ocean plastic can persist in sea surface waters, eventually accumulating in remote areas of the world’s oceans. Here we characterize and quantify a major ocean plastic accumulation zone formed in subtropical waters between California and Hawaii: The Great Pacific Garbage Patch (GPGP). Our model, calibrated with data from multi-vessel and aircraft surveys, predicted at least 79 (45-129) thousand tonnes of ocean plastic are floating inside an area of 1.6 million km2; a figure four to sixteen times higher than previously reported. We explain this difference through the use of more robust methods to quantify larger debris. Over three-quarters of the GPGP mass was carried by debris larger than 5 cm and at least 46% was comprised of fishing nets. Microplastics accounted for 8% of the total mass but 94% of the estimated 1.8 (1.1-3.6) trillion pieces floating in the area. Plastic collected during our study has specific characteristics such as small surface-to-volume ratio, indicating that only certain types of debris have the capacity to persist and accumulate at the surface of the GPGP. Finally, our results suggest that ocean plastic pollution within the GPGP is increasing exponentially and at a faster rate than in surrounding waters.
- Computational science, Great Pacific Garbage Patch, Marine debris, Oceanography, Plastic pollution
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Challenges in modelling detailed surface circulation on the Korea / Tsushima Strait

Conference presentation
February 2016, Ocean Sciences Meeting

Joao Lima Rego, Firmin Zijl, Bruno Sainte-Rose, Frank Kleissen and Wouter Kranenbourg
- Publication type: Conference
- Conference: Ocean Sciences Meeting
- Collaborators: Deltares (Netherlands)
- Submitted: 13.02.2016
- Published: 23.02.2016
Abstract

A detailed three-dimensional hydrodynamic model was set up to study surface circulation around Tsushima Island (Japan) located in the middle of the Korea / Tsushima Strait (KTS). This detailed 3D model was forced by a regional depth-averaged model covering the entire KTS, a shallow channel (sill depth of about 140 m) connecting the broad, shallow East China Sea (depths of 50-1000m) to the much deeper Sea of Japan (depths exceeding 2000m). Detailed surface currents were needed for a study supporting The Ocean Cleanup Foundation, investigating a floating barrier to capture floating litter affecting the southwest coast of Tsushima island. The Tsushima Warm Current (TWC) transports heat and materials through the KTS, from the East China Sea to the southern Japan Sea; tidal currents are of similar magnitude to the TWC in this shallow strait. The island of Tsushima distorts these currents and the winds over the strait drive the wind-driven flow near the surface. Winter-time cooling induces convection down to the bottom, eliminating summer-time density stratification. Consequently, various kinds of current variations are expected in the KTS. The TWC in the Western Channel is stronger than in the Eastern Channel, and it is stronger in summer and autumn than in winter and spring. The current intensities are greater in the Western Channel, where seasonal variability is also greater: January/February current residuals are of order 0.2 m/s and July/August current residuals of order 0.4 m/s. The ERA Interim dataset (ECMWF) was used to determine relevant temporal patterns in wind speed and direction, and to force both the regional and the detailed models. Off the southwest coast of Tsushima island, the two prevailing wind conditions are from the northeast (August/September with typical counter-current winds) or from the northwest (December/January with typical onshore winds). The regional tidal model was enhanced by adding residual oceanic currents and by including wind forcing. The detailed baroclinic model was nested from the larger model and representative density profiles forced along its boundaries providing realistic stratifications for the different scenarios. Both models were based on the Delft3D-FLOW code. Here we present some of the challenges in this model application and describe major findings.
- Circulation modeling, Hydrodynamics, Numerical modeling
Cetacean Sightings within the Great Pacific Garbage Patch

Scientific note
April 2019, Marine Biodiversity

Susan E. Gibbs, Chandra P. Salgado Kent, Boyan Slat, Damien Morales, Leila Fouda and Julia Reisser
- Publication type: Scientific note
- Journal: Marine Biodiversity
- Collaborators: The Ocean Cleanup Foundation (NL), Centre for Marine Science and Technology, Curin University (AUS), Oceans Blueprint (AUS), Centre for Marine Ecosystems Research (AUS), Blue Planet (AUS), Minderoo Foundation (AUS), School of Biological and Chemical Studies, Queen Mary University (UK), UWA Oceans Institute, University of Western Australia (AUS).
- DOI: 10.1007/s12526-019-00952-0
- Submitted: 12.07.2018
- Accepted: 15.03.2019
- Published: 09.04.2019
Abstract

Here, we report cetacean sightings made within a major oceanic accumulation zone for plastics, often referred to as the ‘Great Pacific Garbage Patch’ (GPGP). These cetacean records occurred in October 2016 and were made by sensors and trained observers aboard a Hercules C-130 aircraft surveying the GPGP at 400 m height and 140 knots speed. Four sperm whales (including a mother and calf pair), three beaked whales, two baleen whales, and at least five other cetaceans were observed. Many surface drifting plastics were also detected, including fishing nets, ropes, floats and fragmented debris. Some of these objects were close to the sighted mammals, posing entanglement and ingestion risks to animals using the GPGP as a migration corridor or core habitat. Our study demonstrates the potential exposure of several cetacean species to the high levels of plastic pollution in the area. Further research is required to evaluate the potential effects of the GPGP on marine mammal populations inhabiting the North Pacific.
- Aerial survey, Cetaceans, Great Pacific Garbage Patch, Marine mammals, Plastic pollution
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Using Numerical Model Simulations to Improve the Understanding of Micro-plastic Distribution and Pathways in the Marine Environment

Article in peer reviewed journal
January 2017, Frontiers Marine Sciences

Britta D. Hardesty, Joseph Harari, Atsuhiko Isobe, Laurent Lebreton, Nikolai Maximenko, James T. Potemra, Erik van Sebille, Dick Vethaak and Chris Wilcox
- Publication type: Article in peer-reviewed journal
- Journal: Frontiers Marine Sciences (2017)
- Collaborators: Commonwealth Scientific and Research Organization (Australia), São Paulo University (Brazil), Kyusshu Universoty (Japan), The Modeling House (New Zealand), University of Hawaii (USA), Imperial College London (United Kingdom), Deltares (The Netherlands), Vrije University (The Netherlands)
- DOI: 10.3389/fmars.2017.00030
- Submitted: 01.11.2016
- Accepted: 25.01.2017
Abstract

Numerical modelling is one of the key tools with which we can gain insight into the distribution of marine litter, especially micro-plastics. Over the past decade, a series of numerical simulations have been constructed that specifically target floating marine litter, based on ocean models of various complexity. Some of these models include the effects of currents, waves and wind as well as a series of processes that impact how particles interact with ocean currents, including fragmentation and degradation. Here, we give an overview of these models, including their spatial and temporal resolution, limitations, availability, and what we have learned from them. Then we focus on floating marine micro-plastics (<5mm diameter) and we make recommendations for experimental research efforts that can improve the skill of the models by increasing our understanding of the processes that govern the dispersion of marine litter. In addition, we highlight the importance of knowing accurately the sources or entry points of marine plastic debris, including potential sources that have not been incorporated in previous studies (e.g. atmospheric contributions). Finally, we identify information gaps and priority work areas for research. We also highlight the need for appreciating and acknowledging the uncertainty that persists regarding the movement, transportation and accumulation of anthropogenic litter in the marine environment.
- Accumulation modeling, Fluxes, Fragmentation, Marine debris, Microplastics, Numerical modeling
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Publications

Future Scenarios of Global Plastic Waste Generation and Disposal

Article in peer reviewed journal
January 2019, Nature, Palgrave Communications

Laurent Lebreton and Anthony Andrady
- Publication type: Article in peer-reviewed journal
- Journal: Nature, Palgrave Communications
- Collaborators: The Ocean Cleanup Foundation (NL), The Modelling House Limited (NZ), North Carolina State University (USA).
- DOI: 10.1057/s41599-018-0212-7
- Submitted: 05.07.2018
- Accepted: 13.12.2018
- Published: 29.01.2019
Abstract

The accumulation of mismanaged plastic waste (MPW) in the environment is a global growing concern. Knowing with precision where litter is generated is important to target priority areas for the implementation of mitigation policies. In this study, using country-level data on waste management combined with high-resolution distributions and long-term projections of population and the gross domestic product (GDP), we present projections of global MPW generation at ~1 km resolution from now to 2060. We estimated between 60 and 99 million metric tonnes (Mt) of MPW were produced globally in 2015. In a business-as-usual scenario, this figure could triple to 155–265 Mt y−1 by 2060. The future MPW load will continue to be disproportionately high in African and Asian continents even in the future years. However, we show that this growth in plastic waste can be reduced if developing economies significantly invest in waste management infrastructures as their GDP grows in the future and if efforts are made internationally to reduce the fraction of plastic in municipal solid waste. Using our projections, we also demonstrate that the majority of MPW (91%) are transported via watersheds larger than 100 km2 suggesting that rivers are major pathways for plastic litter to the ocean.
- land-based plastic pollution, plastic pollution projection, river pollution, waste management
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A Methodology to Characterize Riverine Macroplastic Emission Into the Ocean

Article in peer-reviewed journal
October 2018, Frontiers in Marine Science

Tim van Emmerik, Thuy-Chung Kieu-Le, Michelle Loozen, Kees van Oeveren, Emilie Strady, Xuan-Thanh Bui, Matthias Egger, Johnny Gasperi, Laurent Lebreton, Phuoc-Dan Nguyen, Anna Schwarz, Boyan Slat and Bruno Tassin
- Publication type: Article in peer-reviewed journal
- Journal: Frontiers in Marine Science
- Collaborators: The Ocean Cleanup Foundation (NL), CARE, Ho Chi Min University of Technology (VN), Faculty of Geology and Petroleum Engineering, Ho Chi Minh City University of Technology (VN), CNRS, IRD, Grenoble INP, IGE, University of Grenoble Alpes (FR), Faculty of Environment and Natural Resources, Ho Chi Minh City University of Technology (VN), Laboratoire Eau, Environnement, Systèmes Urbains (LEESU), Université Paris-Est (FR), The Modelling House Limited (NZ).
- DOI: 10.3389/fmars.2018.00372
- Submitted: 25.06.2018
- Accepted: 25.09.2018
- Published: 17.10.2018
Abstract

Land-based macroplastic is considered one of the major sources of marine plastic debris. However, estimations of plastic emission from rivers into the oceans remain scarce and uncertain, mainly due to a severe lack of standardized observations. To properly assess global plastic fluxes, detailed information on spatiotemporal variation in river plastic quantities and composition are urgently needed. In this paper, we present a new methodology to characterize riverine macroplastic dynamics. The proposed methodology was applied to estimate the plastic emission from the Saigon River, Vietnam. During a 2-week period, hourly cross-sectional profiles of plastic transport were made across the river width. Simultaneously, sub-hourly samples were taken to determine the weight, size and composition of riverine macroplastics (>5 cm). Finally, extrapolation of the observations based on available hydrological data yielded new estimates of daily, monthly and annual macroplastic emission into the ocean. Our results suggest that plastic emissions from the Saigon River are up to four times higher than previously estimated. Importantly, our flexible methodology can be adapted to local hydrological circumstances and data availability, thus enabling a consistent characterization of macroplastic dynamics in rivers worldwide. Such data will provide crucial knowledge for the optimization of future mediation and recycling efforts.
- research methodology, river pollution
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Sensing Ocean Plastics with an Airborne Hyperspectral Shortwave IR Imager

Article in peer reviewed journal
September 2018, Environmental Science & Technologys

Shungudzemwoyo P. Garaba, Jen Aitken, Boyan Slat, Heidi M. Dierssen, Laurent Lebreton, Oliver Zielinski and Julia Reisser
- Publication type: Article in peer-reviewed journal
- Journal: Environmental Science & Technology
- Collaborators: The Ocean Cleanup Foundation (NL), Department of Marine Sciences, University of Connecticut (US), Marine Sensor Systems Group, Carl von Ossietzky University of Oldenburg (DE), Teledyne Optech (USA), The Modelling House (NZ), Australian Institute of Marine Science, Indian Ocean Marine Research Centre (AUS), Red Sea Research Center, King Abdullah University of Science and Technology (SA).
- DOI: 10.1021/acs.est.8b02855
- Submitted: 28.05.2018
- Accepted: 20.08.2018
- Published: 25.09.2018
Abstract

Here, we present a proof-of-concept on remote sensing of ocean plastics using airborne shortwave IR (SWIR) imagery. We captured red, green, and blue (RGB) and hyperspectral SWIR imagery with equipment mounted on a C-130 aircraft surveying the “Great Pacific Garbage Patch” at a height of 400 m and a speed of 140 knots. We recorded the position, size, color, and type (container, float, ghost net, rope, and unknown) of every plastic piece identified in the RGB mosaics. We then selected the top 30 largest items within each of our plastic type categories (0.6−6.8 m in length) to investigate SWIR spectral information obtained with a SASI-600 imager (950−2450 nm). Our analyses revealed unique SWIR spectral features common to plastics. The SWIR spectra obtained (N = 118 items) were quite similar both in magnitude and shape. Nonetheless, some spectral variability was observed, likely influenced by differences in the object optical properties, the level of water submersion, and an intervening atmosphere. Our simulations confirmed that the ∼1215 and ∼1732 nm absorption features have potential applications in detecting ocean plastics from spectral information. Our study also explores the potential of SWIR remote sensing technology for detecting and quantifying ocean plastics, thus providing relevant information to those developing better monitoring solutions for ocean plastic pollution. Ocean plastic can persist in sea surface waters, eventually accumulating in remote areas of the world’s oceans. Here we characterize and quantify a major ocean plastic accumulation zone formed in subtropical waters between California and Hawaii: The Great Pacific Garbage Patch (GPGP). Our model, calibrated with data from multi-vessel and aircraft surveys, predicted at least 79 (45-129) thousand tonnes of ocean plastic are floating inside an area of 1.6 million km2; a figure four to sixteen times higher than previously reported. We explain this difference through the use of more robust methods to quantify larger debris. Over three-quarters of the GPGP mass was carried by debris larger than 5 cm and at least 46% was comprised of fishing nets. Microplastics accounted for 8% of the total mass but 94% of the estimated 1.8 (1.1-3.6) trillion pieces floating in the area. Plastic collected during our study has specific characteristics such as small surface-to-volume ratio, indicating that only certain types of debris have the capacity to persist and accumulate at the surface of the GPGP. Finally, our results suggest that ocean plastic pollution within the GPGP is increasing exponentially and at a faster rate than in surrounding waters.
- Aerial survey, Marine debris, Oceanography, Plastic pollution, Remote sensing
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Pollutants in Plastics within the North Pacific Subtropical Gyre

Article in peer reviewed journal
December 2017, Environmental Science & Technology

Qiqing Chen, Julia Reisser, Serena Cunsolo, Christiaan Kwadijk, Michiel Kotterman, Maira Proietti, Boyan Slat, Francesco F. Ferrari, Anna Schwarz, Aurore Levivier, Daqiang Yin, Henner Hollert and Albert A. Koelmans
- Publication type: Article in peer-reviewed journal
- Journal: Environmental Science & Technology
- Collaborators: The Ocean Cleanup Foundation (NL), Department of Ecosystem Analysis, Institute for Environmental Research, ABBt – Aachen Biology and Biotechnology, RWTH Aachen University (DE), State Key Laboratory of Estuarine and Coastal Research, East China Normal University (CN), School of Civil Engineering and Surveying, Faculty of Technology, Wageningen Marine Research, Wageningen University & Research (NL), Instituto de Oceanografia, Universidade Federal do Rio Grande (BR), State Key Laboratory of Yangtze River Water Environment, College of Environmental Science and Engineering (CN), Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University & Research (NL)
- DOI: 10.1021/acs.est.7b04682
- Submitted: 11.09.2017
- Accepted: 29.11.2017
- Published: 21.12.2017
Abstract

Here we report concentrations of pollutants in floating plastics from the North Pacific accumulation zone (NPAC). We compared chemical concentrations in plastics of different types and sizes, assessed ocean plastic potential risks using sediment quality criteria, and discussed the implications of our findings for bioaccumulation. Our results suggest that at least a fraction of the NPAC plastics is not in equilibrium with the surrounding seawater. For instance, ‘hard plastic’ samples had significantly higher PBDE concentrations than ‘nets and ropes’ samples, and 29% of them had PBDE composition similar to a widely used flame-retardant mixture. Our findings indicate that NPAC plastics may pose a chemical risk to organisms as 84% of the samples had at least one chemical exceeding sediment threshold effect levels. Furthermore, our surface trawls collected more plastic than biomass (180 times on average), indicating that some NPAC organisms feeding upon floating particles may have plastic as a major component of their diets. If gradients for pollutant transfer from NPAC plastic to predators exist (as indicated by our fugacity ratio calculations), plastics may play a role in transferring chemicals to certain marine organisms.
- Bioaccumulation, Chemical oceanography, Ecotoxicology, Marine debris, Microplastics, Persistent organic pollutants, Plastic pollution, Risk analysis
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Quantification of Medium and Large Debris in the Great Pacific Garbage Patch Using Visual Observations from Aerial Surveys

Technical Report
September 24, 2017

Salgado Kent C, Reisser J, Gibbs SE, Fouda L, Morales D and Kniest H
- Type: Technical report
- Collaborators: Centre for Marine Science and Technology, Curtin University (Australia), The Ocean Cleanup (The Netherlands), University of New Castle (Australia)
- Support provided from: Teledyne Optech, International Air Response, and Moffett Federal Airfield.
- DOI: 10.13140/RG.2.2.10025.29287
Abstract

The Ocean Cleanup Aerial Expedition used visual observation teams and sensors installed on the aircraft to detect floating debris within the so-called Great Pacific Garbage Patch. This document specifically reports on the visual observations conducted during these aerial surveys in October 2016.
- Aerial survey, Great Pacific Garbage Patch, Plastic pollution, Visual observation
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River Plastic Emissions to the World’s Oceans

Article in peer reviewed journal
June 2017, Nature Communications

Laurent C. M. Lebreton, Joost van der Zwet, Jan-Willem Damsteeg, Boyan Slat, Anthony Andrady and Julia Reisser
- Publication type: Article in peer-reviewed journal
- Journal: Nature Communications
- Collaborators: The Modelling House (New Zealand), HKV Consultants (The Netherlands), North Carolina State University (USA)
- DOI: 10.1038/NCOMMS15611
- Submitted: 27.10.2017
- Accepted: 11.04.2017
- Published: 07.06.2017
Abstract

Plastics in the marine environment have become a major concern because of their persistence at sea, and adverse consequences to marine life and potentially human health. Implementing mitigation strategies requires an understanding and quantification of marine plastic sources, taking spatial and temporal variability into account. In this study, we present a global model of plastic inputs from rivers into oceans based on waste management, population density and hydrological information. Our model is calibrated against measurements available in the literature. We estimate that between 1.15 and 2.41 million tonnes of plastic waste currently enters the ocean every year from rivers, with over 74% of emissions occurring between May and October. The top 20 polluting rivers, mostly located in Asia, account for 67% of the global total. The findings of this study provide baseline data for ocean plastic mass balance exercises, and assist in prioritising future plastic debris monitoring and mitigation strategies.
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Extracting DNA from ocean microplastics: a method comparison study

Article in peer reviewed journal
November 2016, Analytical Methods 9

Pavla Debeljak, Maria Pinto, Julia Reisser, Francesco F. Ferrari, Ben Abbas, Mark C. M. van Loosdrecht, Boyan Slat and Gerhard J. Herndl
- Publication type: Article in peer-reviewed journal
- Journal: Analytical Methods 9, 1521-1526 (2017)
- Collaborators: University of Vienna (Austria), Universidade Federal do Rio Grande (Brazil), Delft University of Technology (The Netherlands), NIOZ Netherlands Institute of Sea Research (The Netherlands)
- DOI: 10.1039/C6AY03119F
- Submitted: 17.11.2016
- Accepted: 20.11.2016
- Published: 21.11.2016
Abstract

The ubiquity of plastics in oceans worldwide raises concerns about their ecological implications. Suspended microplastics (<5 mm) can be ingested by a wide range of marine organisms and may accumulate up the food web along with associated chemicals. Additionally, plastics provide a stable substrate to a wide range of organisms and, owing to their widespread dispersal, may function as vectors for harmful and invasive species. Despite the growing application of molecular techniques to study ocean microplastic colonizers, to date there is no comparative study on DNA extraction methods for ocean plastic biofilms. The present study aims to fill this gap by comparing DNA yield, amplification efficiency, costs and processing time of different DNA extraction techniques applied to oceanic microplastics. DNA was extracted with five methods (four extraction kits, and standard phenol:chloroform purification) using two mechanical lysis techniques (bead beating and cryogenic grinding with liquid nitrogen) applied to three plastic quantities (1, 15, and 50 fragments per extraction) and size classes (0.05–0.15 and 0.15–0.5 mm). All methods resulted in DNA suitable for downstream applications and were successfully amplified. Overall, the Qiagen Puregene Tissue kit yielded relatively high DNA concentrations for most sizes and amounts of plastics at relatively low costs and short processing time. This study provides a detailed evaluation of DNA extraction methods from ocean plastics, and may assist future research using molecular techniques to study ocean plastic biofilms.
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The Effect of Particle Properties on the Depth Profile of Buoyant Plastics in the Ocean

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
Abstract

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
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The vertical distribution of buoyant plastics at sea

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
Abstract

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.
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Hydrodynamics and Capture Efficiency of Plastic Cleanup Booms: Part 1, Experiments and Dynamic Analysis

Conference with peer-reviewed proceedings
February 2017, ASME International Conference on Offshore Mechanics & Arctic Engineering

Roberto Brambini, Benedicte Dommergues, Hannah Maral and Bruno Sainte-Rose
- Publication type: Conference with peer reviewed proceedings
- Conference: Conference on Ocean Offshore & Arctic Engineering
- Collaborators: Technische Universität Munchen (Germany)
- Submitted: 06.01.2017
- Accepted: 27.02.2017
Abstract

To reduce the threatening consequences of plastic pollution on marine ecosystems and global economy, The Ocean Cleanup (TOC) Foundation develops technologies to extract, prevent, and intercept plastic debris from coastal and oceanic environments. The core technology being optimized is the use of floating booms placed perpendicular to the main ocean plastic flow so it can concentrate plastic debris to a point where it can be extracted, shipped and processed in a cost-effective manner. To better understand the behavior of such a system in the vertical plane and to calibrate dynamic analysis models as well as Computational Fluid Dynamics (CFD) models, TOC conducted model tests of a portion of the boom at 1:5 scale. These tests were carried out in the Concept Basin at the Maritime Research Institute of the Netherlands (MARIN). The aim of this paper is to present those tests along with the assessment of the dynamics of the boom and the validation of a dynamic analysis model to predict the mooring loads on the system.
- Hydrodynamics, Model testing, Numerical modeling, Offshore engineering
Hydrodynamics and Capture Efficiency of Plastic Cleanup Booms: Part II, 2D Vertical Capture Efficiency and CFD Validation

Conference with peer reviewed proceedings
February 2017, ASME International Conference on Offshore Mechanics & Arctic Engineering

Benedicte Dommergues, Roberto Brambini, Rene Mettler, Zaki Abiza and Bruno Sainte-Rose
- Publication type: Conference with peer-reviewed proceedings
- Conference: Conference on Ocean Offshore & Arctic Engineering
- Collaborators: ETH Zurich (Switzerland), XFlow - a Dassault Systemes company (Madrid)
- Submitted: 06.01.2017
- Accepted: 27.02.2017
Abstract

To mitigate the growing impact of plastic pollution on marine ecosystems and global economy, The Ocean Cleanup (TOC) Foundation develops technologies to extract, prevent, and intercept plastic debris from coastal and oceanic environments. The core technology being optimized is the use of floating booms placed perpendicular to the main ocean plastic flow so it can concentrate plastic debris to a point where it can be extracted, shipped and processed in a cost-effective manner. To investigate the capture efficiency of such a system, TOC conducted model scaled tests at the Dutch research institute MARIN. The objective of this paper is to present those tests along with the assessment of an hydrodynamic model and a CFD model to predict the dynamics of a rigid boom on one hand and the validation of this CFD model to predict the capture efficiency of such a boom.
- CFD, Lagrangian particles, Model testing, Offshore engineering
Multi-scale Numerical Analysis of the Field Efficiency of an Ocean Plastic Cleanup Array

Conference with peer-reviewed proceedings
June 2016, ASME International Conference on Offshore Mechanics & Arctic Engineering

Bruno Sainte-Rose, Laurent Lebreton, Joao Lima Rego, Frank Kleissen and Julia Reisser
- Publication type: Conference with peer-reviewed proceedings
- Conference: Conference on Ocean Offshore & Arctic Engineering
- Collaborators: Deltares (The Netherlands)
- DOI: 10.1115/OMAE2016-54926
- Submitted: 01.01.2016
- Accepted: 25.02.2016
- Published: 24.06.2016
Abstract

The impact of plastic pollution on marine ecosystems and global economy has been drawing public concern since the end of the 20th century. To mitigate this issue, The Ocean Cleanup (TOC) Foundation is developing technologies to extract, prevent, and intercept plastic debris from coastal and oceanic environments. The core technology being optimized is the use of floating booms placed perpendicular to the main ocean plastic flow so it can concentrate plastic debris to a point where it can be extracted, shipped and processed in a cost-effective manner. In order to optimize the system’s field efficiency (i.e. mass of ocean plastic captured per length of floating boom), a multiscale approach has been elaborated, where temporal and spatial scales span over several orders of magnitude. Here we introduce this general multi-scale method alongside its assumptions and multi-scale models. We then describe two application examples, the first corresponding to our coastal pilot in the Japanese island of Tsushima and the second related to our main cleanup target area: the so-called Great Pacific Garbage Patch, situated between Hawaii and the US west coast.
- CFD, Circulation modeling, Lagrangian particles, Multi-scale models, Numerical modeling
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Modelling floating plastic origin, transport and accumulation in the world’s ocean

Conference presentation
March 2017, Association for the Sciences of Limnology and Oceanography

Laurent C. M. Lebreton, Julia Reisser and Bruno Sainte-Rose
- Publication type: Conference presentation
- Conference: (ASLO) Association for the Sciences of Limnology and Oceanography
- Session number: 050
- Date: 03.03.2017
Abstract

Marine debris and particularly plastic litter represent a major threat for ecosystems, human health and the economy. Understanding the origin, transport and accumulation of floating ocean plastics is critical to assess global risks and impacts. Here we present a global dispersal model for the simulation of marine debris trajectories allowing for variation of debris floatability and shape. Lagrangian particles are advected by multiple environmental forcing terms including sea surface currents, sea surface winds and waves. A leeway drift coefficient is applied to balance hydrodynamic and atmospheric forcing terms. Our model is validated against Surface Velocity Program (SVP) drifter position data. SVP drifters are equipped with a drogue that significantly reduce the atmospheric drag and wave-induced Stokes drift. Most drifters are equipped with a submergence sensor which helps in detecting if the drogue is still attached. We present the comparison between modelled and observed velocities for 2 million daily positions recorded by drogued and undrogued drifters. Further validation is conducted by comparing sightings of debris originating from the 2011 ToHoku tsunami and model-predicted arrival time on North American and Hawaiian shores. Our dispersal model is currently used to simulate the transport and accumulation of plastic marine debris at global scale from multiple particle source scenarios. Model predictions are compared against quantifications of floating plastic debris derived from maritime and airborne in-situ observations.
How the oceans can clean themselves: a feasibility study

Independently published book
June 2014, The Ocean Cleanup

Boyan Slat et al.
- Publication type: Independently published book
- Published: June 2014
Abstract

The research described in this feasibility report indicates that The Ocean Cleanup Array is a feasible and viable method to remove large amounts of plastic pollution from a major accumulation zone known as the Great Pacific Garbage Patch. Computer simulations have shown that floating barriers are suitable to capture and concentrate floating plastic debris. Combined with ocean current models to determine how much plastic would encounter the structure, a cleanup efficiency of 42% of all plastic within the North Pacific gyre can be achieved in ten years using a 100 km Array. In collaboration with offshore experts, it has been determined that this Array can be made and installed using current materials and technologies. The estimated costs are €317 million in total, or €31.7 million per year when depreciated over ten years, which translates to €4.53 per kilogram of collected ocean debris.