Emissions from copper-based antifouling paints are a well-known environmental concern. Up to 40 percent of copper inputs into the Baltic Sea come from antifouling paints on ships and pleasure boats. This is completely unnecessary, according to a new study from the Chalmers University of Technology in Sweden. When the researchers compared copper-based antifouling to a biocide-free silicone-based paint, they found that the eco-friendly alternative was the best at keeping contamination away.
This means we now have a great opportunity to drastically reduce the release of heavy metals to our sensitive sea. “This is the first independent scientific study to show that silicone paint is more effective than copper-based paint in the Baltic Sea region,” says Maria Lagerström, marine environmental science researcher at Chalmers.
Maria Lagerström, with colleagues at the University of Gothenburg, the Swedish Environmental Institute IVL and Chalmers, investigated whether biocide-free silicone paints on the hulls of ships and pleasure boats are a viable alternative to copper-based dip paints to combat contamination. The study was carried out for one year at three facilities in the Baltic Sea region and Skagerrak, and the results are published in the scientific journal. Marine Pollution Bulletin.
Environmentally friendly paints are rarely used
The use of copper in antifouling paints is a known and widespread environmental problem for aquatic plants and organisms in the Baltic Sea. The heavy metal does not degrade in the environment and so it is common in marinas, ports and shipyards to contaminate water, sediment and soil and exceed environmental guideline values for copper. An earlier study by Chalmers shows that antifoulings account for 40 percent of the total copper input into the Baltic Sea.
Since the Baltic Sea is an inland sea, water changes take 25-30 years. This means that the heavy metal remains for a very long time. That’s why it’s important to be aware of the substances we release,’ says Maria Lagerström.
Despite the negative impact of heavy metals on the marine environment, the antifouling market for ships and pleasure craft is dominated entirely by copper-based paints. The market share of silicone-based paints for the marine industry increased from 1 percent in 2009 to 10 percent in 2014. It is estimated that the proportion of boats painted with silicone paint for the recreational boat industry is quite low. And while there are more environmentally friendly options on the market, making the change seem difficult.
Both the shipbuilding industry and the recreational boating industry have one thing in common: they are very traditional. People like to use familiar products and are skeptical as to whether alternative non-toxic solutions really work,’ says Maria Lagerström.
Effective even over a longer period of time
Although the study of the different antifoulings was completed after twelve months, the results proved to be permanent over time.
“We actually left our test panels in one of the test areas. These have been under the surface for over two years now. “We can see that the silicone paint still works well and more importantly, it works better than the copper paint,” says Maria Lagerström.
More on research and antifoulings
- Scientific article ‘Are silicone antifouling coatings a viable and environmentally sustainable alternative to biocidal antifouling coatings in the Baltic Sea region?‘ It was published in the journal Marine Pollution Bulletin.
- The work is led by Maria Lagerström, Anna-Lisa Wrange, Dinis Reis Oliveira, Lena Granhag, Ann I. Larsson and Erik Ytreberg.. The researchers are at Chalmers University of Technology, the University of Gothenburg and the Swedish Environment Institute IVL.
- Conventional antifouling paints prevent contamination by constantly filtering copper and/or other toxic substances that are toxic to marine organisms. For silicone paints, it is instead the smooth surface features that make it difficult for contamination to adhere to the body. The paints are also self-cleaning, meaning any impurities that manage to stick are removed as the hull moves through the water.
- Silicone paint is based on silicon material, which is produced using silicon oxide extracted from sand. The scientific article’s collection of ecotoxicological studies shows that silicone paints are significantly less harmful to the environment than copper paints. However, some silicone paints contain high levels of fluorinated substances known as PFAS, which are very resistant to biodegradation in the environment. However, the silicone dye tested in the study does not contain fluorine.
- The research was funded primarily by the Swedish Transport Administration, within the framework of the Lighthouse Swedish Maritime Competence Center and the Sustainable Maritime project.
materials provided by Chalmers University of Technology. Note: Content can be edited for style and length.