Leachates of anti-fouling paints for use on ships and leisure boats are examined for their ecotoxicological potential. Paint leachates were produced in both 7‰ artificial (ASW) and natural seawater (NSW) and tested on three organisms, the bacterium Vibrio fischeri, the macroalga Ceramium tenuicorne, and the crustacean Nitocra spinipes. Generally, leaching in ASW produced a more toxic leachate and was up to 12 times more toxic to the organisms than was the corresponding NSW leachate. The toxicity could be explained by elevated concentrations of Cu and Zn in the ASW leachates. Of the NSW leachates, those from the ship paints were more toxic than those from leisure boat paints. The most toxic paint was the biocide-free leisure boat paint Micron Eco. This implies that substances other than added active agents (biocides) were responsible for the observed toxicity, which would not have been discovered without the use of biological tests.

The most effective biocide used historically in antifouling paints is tributyltin (TBT). However, due to its extreme toxicity to non-target organisms and its persistence in the environment, the use of TBT and other organotin compounds (OTCs) was restricted in EU on leisure boats and ships in 1989 and 2003, respectively. Nevertheless, studies worldwide still report TBT to be released from both ships and leisure boats. Here, we present a new application for a field portable X-ray fluorescence spectrometer (XRF) used for screening for organotin paint through measurements of tin (Sn) on leisure boats and ships. Measurements on ships built after the restrictions showed concentrations of up to 68 mu g Sn/cm(2), likely due to impurities of inorganic Sn, as shown through chemical analysis of 21 organotin-free paints. A threshold value of 100 mu g Sn/cm(2) is suggested, where exceedance indicates presence of OTCs. Screening with the XRF method showed 10% of the commercial vessels (n = 30) and 23-29% of leisure boats (n = 693, investigated in this and in a previous study) to hold concentrations exceeding 100 mu g Sn/cm(2). The XRF technique presented here provides a useful tool for quick screening and identification of vessels holding banned organotin paint.

Antifouling paints are biocidal products applied to ship and boat hulls in order to prevent the growth and settlement of marine organisms, i.e. fouling. The release of biocides from the surface of the paint film act to repel or poison potential settling organisms. Currently, the most commonly used biocide in antifouling paints is cuprous oxide. In the EU, antifouling products are regulated under the Biocidal Products Regulation (BPR), which states that the recommended dose should be the minimum necessary to achieve the desired effect. For antifouling products, the dose is measured as the release rate of biocide(s) from coating. In this study, the release rates of copper and zinc from eight different coatings for leisure boats were determined through static exposure of coated panels in four different harbors located in Swedish waters along a salinity gradient ranging from 0 to 27 PSU. The results showed the release rate of copper to increase with increasing salinity. Paints with a higher content of cuprous oxide were also found to release larger amounts of copper. The coatings' ability to prevent biofouling was also evaluated and no significant difference in efficacy between the eight tested products was observed at the brackish and marine sites. Hence, the products with high release rates of copper were equally efficient as those with 4 - 6 times lower releases. These findings suggest that current antifouling paints on the market are leaching copper in excess of the effective dose in brackish and marine waters. Additionally, the results from the freshwater site showed no benefit in applying a copper-containing paint for the purpose of fouling prevention. This indicates that the use of biocidal paints in freshwater bodies potentially results in an unnecessary release of copper. By reducing the release rates of copper from antifouling paints in marine waters and restricting the use of biocidal paints in freshwater, the load of copper to the environment could be substantially reduced.

The aim of this doctoral thesis was to investigate and improve the risk assessment of anti-fouling paints. A new method, the Petri-dish method, was developed to determine release rates of copper and zinc from anti-fouling paints (Paper I). The release rates of zinc were substantially higher from the biocide-free leisure boat paints than from the biocide-leaching paints. In Paper II, the potential toxicity of paint leachates was assessed and the biocide-free paint proved to be the most toxic paint investigated. Zinc, a supposedly non-biocidal ingredient in copper-based and other antifouling paints, was found to contribute significantly to the observed toxicity of all leisure boat paints investigated. This means that risk assessment of an anti-fouling paint based on only the active biocidal ingredient in the formula is insufficient. A more holistic approach, based on hazard identification and dose-response assessment of anti-fouling paint leachate, with all ingredients taken into consideration, is recommended. This can be achieved by the Petri-dish method, which combines chemical analysis with ecotoxicological tests of paint leachates. In Paper III and IV, the effects of salinity and organic matter on copper bioaccumulation and toxicity to the red macroalga Ceramium tenuicorne were studied. Salinity had only a minor effect in ameliorating copper toxicity, whereas the organic matter concentration had a significant effect in reducing the bioavailability and hence copper toxicity at all salinities tested. Copper uptake and bioaccumulation by C. tenuicorne showed that the macroalga could access a sizeable fraction of organically-complexed copper in addition to Cu²⁺, when Cu²⁺ concentration to the cell membrane is diffusion limited. This observation implies that the setting of environmental quality standards (EQSs) for copper and other metals through the Biotic Ligand Model (BLM) is inappropriate in predicting copper uptake and hence toxicity to C. tenuicorne.

Quantification of release rates of Cu and Zn from biocide-containing and biocide-free antifouling paints, used on ships and leisure boats, were conducted in brackish artificial and natural seawater (ASW and NSW). To determine the toxicity of Cu and Zn, toxicity tests were performed with organisms from three trophic levels. Generally, the release rates of both Cu and Zn were higher in ASW than in NSW for the tested paints. The release rate of Cu in NSW was higher from the ship paints (3.2–3.6 μg cm-2d-1) than from the leisure boat paint (1.1 μg cm-2d-1). Biocide-free paints leached more Zn (4.4–8.2 μg cm-2d-1) than the biocide-containing paints (0.7–3.0 μg cm-2d-1). In conclusion, both Cu and Zn may be toxic to non-target organisms in areas with high boat density. To account for ecological risk associated with anti-fouling paints, Zn as wells as the active ingredients should be considered.

Current water quality criteria (WQC) regulations on copper toxicity to biota are still based on total dissolved (<0.4 μm membrane filter) copper concentrations with a hardness modification for freshwaters. There are however ongoing efforts to incorporate metal speciation in WQC and toxicity regulations (such as the biotic ligand model-BLM) for copper and other metals. Here, we show that copper accumulation and growth inhibition of the Baltic macroalga Ceramium tenuicorne exposed to copper in artificial seawater at typical coastal and estuarine DOC concentrations (similar to 2−4 mg/L-C as fulvic acid) are better correlated to weakly complexed and total dissolved copper concentrations rather than the free copper concentration [Cu²⁺]. Our results using a combination of competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV) measurements and model calculations (using visual MINTEQ incorporating the Stockholm Humic Model) show that copper accumulation in C. tenuicorne only correlates linearly well to [Cu²⁺] at relatively high [Cu²⁺] and in the absence of fulvic acid. Thus the FIAM fails to describe copper accumulation in C. tenuicorne at copper and DOC concentrations typical of most marine waters. These results seem to indicate that at ambient total dissolved copper concentration in coastal and estuarine waters, C. tenuicorne might be able to access a sizable fraction of organically complexed copper when free copper concentration to the cell membrane is diffusion limited.

Cu is a major active component in anti-fouling paints, which may reach toxic levels in areas with intense boat traffic and therefore is a metal of environmental concern. The bioavailability of metals is influenced by factors such as salinity and organic matter measured as total organic carbon (TOC). The influence of these two factors was studied, with a focus on brackish water conditions, by exposing a marine and a brackish water clone of the red macroalga Ceramium tenuicorne to Cu in different combinations of artificial seawater (salinity 5–15‰) and TOC (0–4 mg/L) in the form of fulvic acid (FA). In addition, the toxicity of Cu to both clones was compared in salinity 10‰ and 15‰. The results show that by increasing TOC from 0 to 2 and 4 mg/L, Cu was in general less toxic to both algal clones at all salinities tested (p<0.05). The effect of salinity on Cu toxicity was not as apparent, both a positive and negative effect was observed. The brackish water clone showed generally to be more sensitive to Cu in salinity 10‰ and 15‰ than the marine counterpart. In conclusion, FA reduced the Cu toxicity overall. The Cu tolerance of both strains at different salinities may reflect their origin and their adaptations to marine and brackish water.

To ensure sustainable use of antifouling paints, the European Union have developed a new environmental risk assessment tool, which a product must pass prior to its placement on the market. In this new tool, environmental concentrations are predicted based on estimated release rates of biocides to the aquatic environment and risk characterization ratios are calculated in regional spreadsheets. There are currently two methods in use to predict release rates of biocides; a calculation method and a laboratory method. These methods have been believed to overestimate environmental release of biocides and therefore fixed correction factors to reduce the release rate can be applied. An alternative method, known as the XRF method, has recently been developed and used to derive field release rates from antifouling paints. The aim of this study was to review the new environmental risk assessment tool and assess how the choice of release rate method and application of correction factors impact the approval of antifouling paint products. Eight coatings were environmentally risk assessed for usage in four European marine regions; Baltic, Baltic Transition, Atlantic and Mediterranean; by applying release rates of copper and zinc determined with the different methods. The results showed none of the coatings to pass the environmental risk assessment in the Baltic, Baltic Transition and the Mediterranean if field release rates were used. In contrast, most of the coatings passed if the correction factors were applied on the release rates obtained with the calculation or laboratory method. The results demonstrate the importance of release rate method choice on the outcome of antifouling product approval in EU. To reduce the impact of antifouling paints on the marine environment it is recommended that no correction factors should be allowed in the environmental risk assessment or preferably that site-specific field release rates are used. If the regulation in the European Union (and elsewhere) continues to allow correction factors, the pressure of biocides to the environment from leisure boating will result in degradation of marine ecosystems.

Despite the ban of applying TBT coatings on leisure boats in the late 80s, recent studies show an ongoing spread of TBT from leisure boats, particularly during hull cleaning events. Therefore, countries in EU have adopted expensive measures to clean this wash water. A more cost-efficient measure is to focus directly on the source, i.e. identify leisure boats with high concentrations of TBT and prescribe boat owners to remove the paint. We have developed a new antifouling paint application for a handheld X-ray fluorescence (XRF) analyzer to be used for identifying boats with high area concentrations (mu g/cm(2)) of Sn (indication that the hull contains TBT paint residues). Copper and zinc are also included in the application since these metals are used in the vast majority of today's paints. A blind test with up to four layers of TBT-, copper- and zinc-based paints showed good correlation between XRF-measured area concentrations and chemically analyzed concentrations. Future usage of the applications involves identification of boat hulls in particular with high Sn concentrations and also with high Cu and Zn concentrations. This method has the potential to become a useful tool in regulatory management of existence and use of toxic elements on boat hulls.