Reducing antifouling toxins to the Baltic Sea
The coastal ecosystem is of utmost importance to the well-being of the whole of the Baltic Sea. It is vital as the spawning ground and nursery for a wide range of organisms, i.e., fish, algae and invertebrates. It is also important as feeding grounds for pelagic fish and a source of pleasure for the human population. Some 3.5 million leisure boats in the Baltic Sea use the coastal areas for recreational boating. A great majority of these boats use toxic compounds to prevent fouling organisms to attach to the boat hull (antifouling). Today, the most commonly used biocide in antifouling paints is copper oxide but other prohibited compounds such as TBT is still being released to the environment during hull cleaning and maintenance work.
The overall objective of the CHANGE project is to reduce to a minimum the supply of toxic compounds from antifouling paints used on leisure boats in the Baltic Sea. This will be achieved by changing antifouling practices on leisure boats into a sustainable consumption of antifouling products and techniques. For that purpose CHANGE will develop an interdisciplinary and integrated scientific platform of Business administration, environmental law and natural science that will work in close collaboration with stakeholders and end-users to identify the interrelated impacts and driving forces inherent in the problem.
Baltic Sea – a sensitive polluted sea area
Waste water and emissions from around 80 million people in 14 countries are discharged into the Baltic Sea making it a highly polluted sea area. The Baltic Sea is one of the largest brackish water environments in the world and was appointed by IMO in 2004 as a Particular Sensitive Sea Area (PSSA). The basis for the status as PSSA is the low biodiversity because of the brackish environment, the slow water exchange with the North Sea and a water retention time of ca 25 years.
Biofouling is the colonization and subsequent growth of sessile organisms on all manmade surfaces in the sea, including boat hulls. Marine biofouling is made up of a wide range of organisms, i.e., slime forming microorganisms, algae and invertebrates. The barnacle is considered to be the most serious fouler because of great difficulties in removing barnacle base plates from boat hulls. Biofouling increases drag and weight and thereby fuel consumption. Biofouling also decreases vessel manoueverability. Consequently, biofouling is a safety issue and a continual, heartfelt problem for any boat owner.
Lower fouling pressure in the Baltic Sea
The fouling pressure is lower in the Baltic Sea compared to fully marine conditions. However, the fouling pressure can vary substantially in the Baltic Sea. Thus it is important to perform evaluation tests on antifouling techniques in high resolution if the data shall be used for developing site-specific recommendation to boat owners.
Boating is contributing to the high levels of contaminants in the Baltic Sea
The use of biocide leaching antifouling paints continuously adds to the distribution of contaminants in the coastal ecosystem. In a recent survey we found that nearly 80 percent of the leisure boats in the Swedish Baltic use paints containing toxic heavy metals, i.e. copper and zinc to prevent biofouling on their hulls. Furthermore, nearly 30 percent of the Baltic Sea leisure boats use an overload of copper that is not necessary considering the relatively mild fouling pressure in the Baltic Sea.
New alarming results suggest that large amounts of TBT still is present in underlying paint layers on leisure boat hulls. Thus, TBT along with large amounts of copper are washed or scraped off to the ground during leisure boat maintenance, thereby contaminating soil, ground water and near coastal waters . In a recent questionnaire survey we found that as many as 80 percent of boat owners in Sweden leave paint disposals on the ground after scraping.
Biocide-free techniques is the solution?
Within CHANGE we will test and evaluate the environ- mental impact of different antifouling methods, including both biocide leaching paints and biocide-free techniques. Our research will be conducted at almost 20 sites and aims to:
- Map the spatial differences in fouling pressure in the Baltic Sea.
- In close collaboration with boat owners test and evaluate the efficiency of different antifouling techniques.
- Map consumer practices related to antifouling products.
- Produce site-specific recommendations to boat owners on effective antifouling technique with low environmental impact.
Coordinator Mia Dahlström Sjögren
Department of Chemistry, Materials and Surfaces
SP Technical Research Institute of Sweden
Phone: +46 (0)10 516 53 40