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Study: Eco-friendly Antifouling Paint Most Effective
According to a recent report, researchers have found that environmentally friendly alternatives to copper-based antifouling paint were best at keeping fouling at bay on ships and vessels.
A team of researchers from Chalmers University of Technology, the University of Gothenburg and the Swedish Environmental Institute IVL investigated whether biocide-free silicone paints are a viable alternative to copper-based bottom paints to combat fouling.
“This means that we now have a great opportunity to drastically reduce the release of the heavy metal into 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,” said Maria Lagerström, researcher in marine environmental science at Chalmers.
Research Findings
According to a previous study from Chalmers University, as much as 40% of copper inputs to the Baltic Sea come from antifouling paints on ships and leisure boats. The heavy metal materials reportedly do not degrade in the environment, contaminating water, sediment and soils in marinas, ports and shipyards.
Lagerström added that it takes 25 to 30 years for the water to be exchanged in the Baltic Sea, because it is inland. This means that the heavy metals can remain for a very long period of time.
However, despite this impact, the antifouling paint market is “dominated” by copper-based paints, with silicone-based paints in the shipping sector making up just 1% of the market in 2009 and raising to 10% by 2014. For the recreational boating sector, the proportion of boats painted with silicone paint is reportedly estimated to be significantly lower.
“Both the shipbuilding industry and the leisure boating sector have one thing in common: they are highly traditional. People like to use the products they are used to, and they are also skeptical as to whether non-toxic alternative solutions really work,’ said Lagerström.
The latest study, which was recently published in the scientific journal Marine Pollution Bulletin, was carried out over a year at three sites in the Baltic Sea region and the Skagerrak. Black painted surfaces were coated with biocide-free silicone-based paint, while red surfaces were coated with copper-based paint. The white surfaces had no antifouling treatment.
The silicone paint is based on silicone, produced using silicone oxide extracted from sand. The university notes that some silicone paints contain highly fluorinated substances, or PFAS, but the paint tested in the study was fluorine-free.
While the traditional antifouling paint continuously leached copper and other toxic substances, the silicone paint utilized its smooth surface properties to make it difficult for fouling to stick to the hull. The silicone is also self-cleaning, meaning any fouling that does stick is removed as the hull moves through the water.
According to the release, the scientific paper’s collection of ecotoxicological studies shows that silicone paints are significantly less harmful to the environment than copper paints.
Additionally, although the study was carried out over 12 months, the test panels were left at one of the test sites, showing that these results were found to persist over time.
“These have now been under the surface for over two years. We can see that the silicone paint still works well and, more importantly, works better than the copper paint,” said Lagerström.
Alongside Lagerström, the study was led by Anna-Lisa Wrange, Dinis Reis Oliveira, Lena Granhag, Ann I. Larsson and Erik Ytreberg. The research was primarily funded by the Swedish Transport Administration, within the framework of the Lighthouse Swedish Maritime Competence Centre and the Sustainable Shipping project.
Green Antifouling Initiatives, Research
Earlier this year, in May, environmental NGO Bellona Foundation, in partnership with marine and protective coatings company Jotun, launched a new initiative to define and implement a new ISO standard for proactive hull cleaning.
The Clean Hull Initiative calls on regulators, shipping companies, ports, coatings manufacturers, technology and service providers, as well as academic and research institutions to focus on biofouling management.
The most common way to combat biofouling, Bellona says, is by using antifouling coatings containing biocides. While coatings alone do not prevent all biofouling, in combination with IWC or dry docking, accumulated fouling can be physically removed.
Cleaning can be proactive (fouling at early stages) or reactive (at later stages), with reactive cleaning posing a higher risk of damaging the coating and further cause release of invasive species into the marine environment. As a result, reactive cleaning is often performed with technology to capture organic debris removed from the hull.
In March, Danish biotech company Cysbio announced it developed a new sustainable replacement for copper in antifouling paints. According to reports, the company has developed and patented a fermentation technology to produce eelgrass acid as a copper replacement.
To find an environmentally friendly alternative, the company looked to biobased materials. Eelgrass, which grows on very low shores and in depths of 10 meters (32.8 feet) deep, can reportedly be used to prevent microbes and other larger organisms from attaching themselves to surfaces.
According to Cysbio, Sweden has fully banned ships with copper paint in the Bay of Bothnia and freshwater lakes, while the Netherlands and California has introduced restrictions that prohibit the sale of ship paint with high concentrations of copper for yachts and recreational vessels.
In addition to concerns over copper, recent studies have shown that paint flakes in general are a large portion of microplastics and other harmful materials found in water. In October last year, a study conducted by the University of Plymouth and the Marine Biological Association (MBA) observed that paint flakes could be one of the most abundant types of microplastic particles found in the ocean.
“Paint particles have often been an overlooked component of marine microplastics, but this study shows that they are relatively abundant in the ocean. The presence of toxic metals like lead and copper pose additional risks to wildlife,” said Andrew Turner, the study’s lead author and associate professor in environmental sciences at the University of Plymouth, in an interview.
These paint flakes also contained high quantities of lead, iron and copper due to having anti-fouling or anti-corrosive properties. Researchers explained that this could pose a threat to the ocean and marine life if ingested.
Later, in December, a research team from the Department of Environmental Sciences at the University of Basel and the Alfred-Wegener Institute at the Helmholtz Centre for Polar and Marine Research on the island of Heligoland published a study analyzing microplastic particles and paint fragments in Antarctica.
Researchers collected 34 surface water samples and 79 subsurface water samples from the remote Weddell Sea in 2018 and 2019. The team took two expeditions in the research vessel, Polarstern. Once filtered, the approximately eight million liters of sea water contained microplastics.
Most recently, a study published in March by the Swiss-based Environmental Action found that paint accounts for 58% of microplastics in the world’s oceans and waterways. According to the research, 1.9 million tons of paint found in oceans and waterways each year outweighs other sources of microplastics, including textile fibers and tire dust.
The total leakage from paint is reportedly estimated to be between 5.2 to 9.8 metric tons per year, with the average being 7.4 metric tons annually and a 40% leakage rate. About a third, or 37%, of this leakage occurs as a result of waste mismanagement and about 18% stems from wear and tear or maintenance of ships and offshore rigs.
