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The contribution of commercial shipping to global marine plastic pollution

Although sea-based sources are generally considered a minor source compared to land-based sources at global scale, shipping has been identified as a key source of plastic pollution in various geographic locations. In order to effectively address marine plastic litter and (micro-)plastics, it is necessary to understand the contribution of individual sources and the pathways from these sources to the environment.

Topic 1: Operational leakages from cargoes of plastic pellets during maritime transportation

A distinct form of marine microplastic pollution is that of pre-production plastic pellets, also called nurdles. These lentil-sized plastic resin particles constitute the most common form of raw materials out of which plastic products are produced. Plastic pellets form the second largest source of microplastics in the marine environment and are found around the world. These very light and small particles disperse very quickly and are extremely difficult to clean up. The origin of plastic pellet pollution is often linked to land-based industrial sites and transportation. However, recent spills resulting from accidents with ships have highlighted the significance of maritime shipping as a source of plastic pellet pollution. In addition, plastic pellets may be released from ships into the ocean as a result of operational leakages during maritime transportation. Unsupported claims are that one out of every ten containerized consignments involves leakages of plastic pellets. Considering the large volumes of primary plastics that are internationally shipped via maritime transport, the contribution of these operational spills and leakages to global plastic pellet pollution may be considerable.

The aim of the current MSc project is to assess the scale and causes of plastic pellet pollution from maritime shipping containers as a result of operational leakages and spills. Thereto you will collect data from logistics providers and cargo owners, in the form of interviews and observations, as well as company data on previous incidents.

Topic 2: Dumping and littering of plastic waste from global maritime shipping

The International Convention for the Prevention of Pollution from Ships (MARPOL) includes regulations aimed at preventing and minimizing different forms of pollution from ships. Annex V of the MARPOL Convention prohibits the discharge of any type of plastics into the marine environment. However, various recent studies on remote shorelines have highlighted significant plastic pollution deriving from shipping activities, presumably as a result of deliberate dumping of plastic waste. Although most items in these studies were found to be produced in China, it remains unclear what kinds of shipping activities are responsible for this illegal form of pollution, which drivers lead to ship-based plastic dumping, and what the scale of the problem is.

The aim of the current MSc project is to explore the shipping activities, drivers and scale of the dumping of plastic waste into the sea by ships. Thereto, different approaches may be considered, including:

  1. Linking observations of presumed ship-based plastic pollution to geospatial data on shipping routes and activities in the form of AIS data;
  2. Crew interviews or questionnaires on experiences with shipboard garbage management on longer journeys, as well as sightings of illegal activities.

Topic 3: Microplastic emissions from marine paints and coatings

Paint particles are a source of microplastics that, up to recently, have been largely overlooked in microplastic research. An emerging body of literature on the topic highlights the significant contribution to overall microplastic pollution and the specific hazards associated with these particles, due to their toxic components. Paints and coatings used on ships are one source of paint particles, that are emitted directly into the marine environment. Maritime paint applications include antifouling coatings, used on the underwater section of the hull to minimize the growth of biofouling, as well as anticorrosive coatings applied on other exterior and interior parts of the vessel and its equipment. Regarding antifouling coatings, most of the paint applications have self-polishing properties, meaning that these are designed to erode over the paint lifetime. Other release mechanisms of paint particles occur throughout the vessel lifetime and include newbuilding activities, paint application, general wear and tear, damage, periodic hull cleaning, maintenance and end of life. Although generic emission factors on paint emissions from above-water applications exist for some of these processes, these lack an empirical basis. To establish effective policies to address this issue, a comprehensive understanding is needed on the underlying processes and their contribution to marine microplastic emissions.

The aim of an MSc project would be to contribute to the general understanding of paint emissions from ships, which could be achieved by various types of research depending on the student’s interest, for instance:

  1. Collecting quantitative, empirical data on paint losses associated with one or more release mechanisms or paint applications, based on observations and/ or expert judgment;
  2. Conducting a stakeholder mapping in combination with modelling approaches, throughout the ship lifecycle, to provide a basis for transdisciplinary data collection and policy making;
  3. Assess possibilities to address plastic pollution from marine paints and coatings through a structured review of existing policy frameworks;
  4. Conducting experiments to assess the fate of eroded paint particles from self-polishing antifouling.

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Contact: Maartje Folbert and Ansje Lohr