The use of biocidal antifouling (AF) paints is the most common way to prevent fouling on leisure boat hulls. The main aim of this thesis was to investigate the pathways through which AF biocides, past and present, may reach the environment through their use on leisure boats and to improve the risk assessment of biocidal AF paints intended for amateur use. The work presented focuses mainly on the Baltic Sea, with emphasis on regulation and risk assessment procedures in Sweden. A new method was developed for the quantification of nowadays banned organotin compounds (OTCs) such as tributyltin (TBT) in paint flakes (paper I). OTCs were detected in hull paint scrapings from three countries around the Baltic Sea. Thus, historic layers of organotin paint on leisure boats may constitute as sources of TBT to the marine environment. Total tin was identified as an indicator for the presence of OTCs on boat hulls, allowing for quicker identification of vessels in need of remediation. Nowadays, most AF paints tend to contain high amounts of copper (Cu) and zinc (Zn). The use of AF paints was shown to cause exceedance of guideline values for these two metals in soil, sediment and water in various investigated marinas (papers II and IV). The pollution of boatyard soil was linked to hull maintenance activities carried out over unprotected ground (paper II). AF paints were also found to impact both the concentration and speciation of dissolved Cu and Zn in two Baltic Sea marinas, with increased concentrations as well as an increased proportion of bioavailable species as a function of an increased number of moored boats (paper IV). A new method utilizing X-Ray Fluorescence (XRF) was used to derive the release rates of Cu and Zn in the field for five commercially available AF paints for amateur use (paper III). Salinity and paint properties were found to be important parameters affecting the release. The in situ release rates were also found to exceed those derived with current standardized release rate methods. Given the high release rates, none of the studied paints should have been approved for the Swedish market. This finding likely explains the exceedance of guideline values for dissolved Cu and Zn in investigated Baltic Sea marinas (paper IV). In conclusion, there is a need for caution when authorizing new biocides as the phasing out of banned substances can be a lengthy process due to their continued presence in historic paint layers. Additionally, paint-specific release rates determined under conditions reflecting the intended use of the product should be used for a more realistic environmental risk assessment of AF paints.

The seasonal variations of dissolved and bioavailable copper (Cu) and zinc (Zn) were studied in two recreational marinas in Sweden and Finland. The time series from the two marinas were characterized by rising concentrations during the spring boat launching, elevated concentrations all through the peak boating season, and decreasing concentrations in autumn when boats were retrieved for winter storage. This pattern shows a clear link between Cu and Zn concentrations and boating activity, with antifouling paints as the principal source. The leaching from antifouling paints was also found to significantly alter the speciation of dissolved Cu and Zn in marina waters, with an increase of the proportion of metals that may be considered bioavailable. This change in speciation, which occurred without any change in dissolved organic carbon (DOC), further increases the environmental risk posed by antifouling paints. In the Swedish marina, dissolved Cu and Zn exceed both Environmental Quality Standards (EQS) and Predicted No Effect Concentrations (PNEC), indicating that the current Swedish risk assessment (RA) of antifouling paints is failing to adequately protect the marine environment. An evaluation of the RA performance showed the underlying cause to be an underestimation of the predicted environmental concentration (PEC) by factors of 2 and 5 for Cu and Zn, respectively. For both metals, the use of inaccurate release rates for the PEC derivation was found to be either mainly (Cu) or partly (Zn) responsible for the underestimation. For Zn, the largest source of error seems to be the use of an inappropriate partitioning coefficient (K-D) in the model. To ensure that the use of antifouling coatings does not adversely impact the sensitive Baltic Sea, it is thus recommended that the K-D value for Zn is revised and that representative release rates are used in the RA procedure.

Antifouling paints are environmentally risk assessed based on their biocidal release rates to the water phase. In situ release rates of copper (Cu) and zinc (Zn) were derived for five commercial paints in two recreational marinas with different salinities (5 and 14 PSU) using an X-Ray Fluorescence spectrometer (XRF). Salinity was found to significantly affect the Cu release, with twice the amount of Cu released at the higher salinity, while its influence on the Zn release was paint-specific. Site-specific release rates for water bodies with salinity gradients, e.g. the Baltic Sea, are therefore necessary for more realistic risk assessments of antifouling paints. Furthermore, the in situ release rates were up to 8 times higher than those generated using standardized laboratory or calculation methods. The environmental risk assessment repeated with the field release rates concludes that it is questionable whether the studied products should be allowed on the Swedish market.

The application of a field portable X-ray fluorescence spectrometer (FPXRF) to measure Cu, Zn, and Pb in soil and sediments at recreational boatyards by Lake Malaren in Sweden was investigated. Confirmatory chemical analysis on freeze-dried samples shows that, ex situ, the FPXRF produces definitive level data for Cu and Zn and quantitative screening data for Pb, according to USEPA criteria for data quality. Good agreement was also found between the ex situ measurements and the in situ screening. At each of the two studied boatyards, >40 in situ soil measurements were carried out. Statistical differences in soil concentration based on land use were consequently found: the areas used for boat storage and maintenance were significantly higher in Cu and Zn than the areas used for car parking and transportation. The metal pollution in the boat storage areas is therefore shown to be directly linked to hull maintenance activities during which metal-containing antifouling paint particles are shed, end up on the ground, and consequently pollute the soil. In the boat storage areas, the Cu and Zn concentrations often exceeded the national guideline values for soil. In this study, they were also shown to increase with increasing age of the boatyard operation. Pb soil concentrations were only elevated at a few measurement points, reflecting the phasing out of Pb compounds from antifouling products over the past 2 decades. In the surface sediments, concentrations of Cu and Zn were 2-3 times higher compared to deeper levels. No decrease in metal concentration with time was found in the sediments, indicating that boat owners are not complying with the ban of biocide-containing paints in freshwater introduced over 20 years ago.

Despite their ban on small vessels in 1989 in the EU, organotin compounds (OTCs) are still being released into the environment due to their presence in historic paint layers on leisure boats. 23 paint samples scraped from recreational boats from three countries around the Baltic Sea were analyzed for total tin (Sn) and OTCs. Two antifouling paint products were also subjected to the same analyses. A new method for the detection of Sn in paint flake samples was developed and found to yield more accurate results compared to four different acid digestion methods. A new method was also developed for the extraction of OTCs from ground paint flakes. This endeavor revealed that existing methods for organotin analysis of sediment may not have full recoveries of OTCs if paint flakes are present in the sample. The hull paint samples had Sn concentrations ranging from 25 to 18,000 mg/kg paint and results showed that tributyltin (TBT) was detected in all samples with concentrations as high as 4.7 g (as Sn)/kg paint. TBT was however not always the major OTC. Triphenyltin (TPhT) was abundant in many samples, especially in those originating from Finland. Several other compounds such as monobutyltin (MBT), dibutyltin (DBT), tetrabutyltin (TeBT), monophenyltin (MPhT) and diphenyltin (DPhT) were also detected. These could be the result of degradation occurring on the hull or of impurities in the paint products as they were also identified in the two analyzed paint products. A linear correlation (r(2) = 0.934) was found between the total tin content and the sum of all detected OTCs. The detection of tin can therefore be used to indicate the presence of OTCs on leisure boats. (C) 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.

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 release of copper (Cu) and zinc (Zn) from vessels and leisure crafts coated with antifouling paints can pose a threat to water quality in semi-enclosed areas such as harbors and marinas as well as to coastal archipelagos. However, no reliable, practical and low-cost method exists to measure the direct release of metals from antifouling paints. Therefore, the paint industry and regulatory authorities are obliged to use release rate measurements derived from either mathematical models or from laboratory studies. To bridge this gap, we have developed a novel method using a handheld X-Ray Fluorescence spectrometer (XRF) to determine the cumulative release of Cu and Zn from antifouling paints. The results showed a strong linear relationship between XRF K_α net intensities and metal concentrations, as determined by ICP-MS. The release of Cu and Zn were determined for coated panels exposed in harbors located in the Baltic Sea and in Kattegat. The field study showed salinity to have a strong impact on the release of Cu, i.e. the release increased with salinity. Contrary, the effect of salinity on Zn was not as evident. As exemplified in this work, the XRF method also makes it possible to identify the governing parameters to the release of Cu and Zn, e.g. salinity and type of paint formulation. Thus, the XRF method can be used to measure environmentally relevant releases of metallic compounds to design more efficient and optimized antifouling coatings.