Oldenburg University scientists have found that protective ship coatings cause microplastic pollution in oceans.
Coatings and paints used on ships contain heavy metals and other additives that are toxic to many organisms. These anti-fouling components are used to protect ships’ hulls from barnacles and other subaquatic organisms and are constantly rubbed off by the wind and waves.
“Our hypothesis is that ships leave a kind of ‘skid mark’ in the water which is of similar significance as a source of microplastics as tire wear particles from cars are on land,” notes lead scientist Dr. Barbara Scholz-Boettcher.
In the autumn of 2016 and 2017, Scholz-Boettcher and her two colleagues Christopher Dibke and Marten Fischer, took water samples from various locations in the German Bight with the research vessel Heincke.
They used stainless steel sieves to filter plastic particles of much less than one millimeter in diameter out of the seawater and then analyzed the chemical composition of the collected particles.
Onshore, the scientists first heated these plastic molecules to temperatures of almost 600 degrees Celsius to break them down into smaller, characteristic fragments.
They were later separated and assigned to different polymer groups based on their mass and chemical properties.
According to Scholz-Boettcher, the results surprised them as the samples contained indicators for polyvinyl chloride (PVC), polymers known as acrylates and polycarbonates.
Their mass accounted for about two-thirds of the total microplastic content in the mean and up to 80 percent in certain samples.
Packaging plastics such as polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET), which were previously estimated to make up the bulk of microplastics in the sea, accounted for a much smaller percentage!
“We believe that these particles originate from ship coatings, where these plastics are used as binders in acrylic paints or epoxy resins, for example,” says Scholz-Boettcher.
These results suggest that far larger quantities of microplastics are produced directly at sea than previously thought.
Image and content: Pexels/University of Oldenburg