D10: Impact of Contaminants - Hydromod

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Integrated Water Resource Management for Important Deep European Lakes and their Catchment Areas EUROLAKES D10: Impact of Contaminants FP5_Contract No.: EVK1-CT1999-00004 Version: 4.0 Date: 25/07/01 File: D10-vers.4.0.doc Page 76 of 136 most toxic substances for aquatic organisms [BUWAL b]. In Switzerland no authorised agricultural pesticide containing TBT but it is still used for wood treatment and has other industrial applications [BECKER-VAN SLOOTEN AND TARRADELLAS, 1994]. On the 1 st of July 1988 a Swiss legalisation came into force banning the selling of antifouling paints containing trialcyl- or triaryltins. Importers and sellers were allowed two years of dispose of their stock. The selling of antifouling paint containing these compounds was illegal after 1 st of July 1990. In France the use of TBT-containing antifoulings has been forbidden since 1982 for vessels less than 25 m in length. [BECKER-VAN SLOOTEN AND TARRADELLAS, 1994/1995]. Nowadays antifouling products contain besides copper a triazine compound which is effective against algae [BUWAL b]. In the marina of Lake Geneva only every fourth boat is painted annually and the boats left in the water during winter [BECKER-VAN SLOOTEN AND TARRADELLAS, 1994]. [BECKER et al 1992] showed high organotin levels in Lake Geneva in 1988 just as the ban came into force. In this work it was shown that the TBT contamination of water, sediment and bivalves was higher in Swiss marinas of Lake Geneva than in the French marinas. This study of [BECKER et al 1992] was designed to compare the organotin concentrations in marinas within two countries - Switzerland and France - having different legislation. Water, sediment and mollusc samples were collected from three Swiss and two French marinas (Figure 10-8). As a reference, a natural site was chosen away from sources of organotin compounds, but presenting similar characteristics to a marina like a sheltered and shallow site. The results of the assessment of butyl- and phenyltin compounds in Lake Geneva are reported in Each value i a mean of 6 samples (3 stations each with one surface and one bottom sample) except for the reference point (2 stations). The range is indicated below in parantheses. TPT has not been detected. (nd = not detected, CH = Switzerland, F = France) Table 10-2, Table 10-3 and Table 10-4. the TBT concentrations ranged from not detected to 1.08 µg/l in water and from 0.03 to 4.76 µg/g dry weight in sediment. The Swiss marinas were up to 20 times more contaminated than the French ones. This difference was more pronounced for the water than for the sediment. Partly it can be explained by the fact that the use of antifouling paints is regulated in France since 1982. Furthermore, the values might reflect the degree of flushing as Geneva and Lausanne are the most enclosed marinas with the poorest water exchange. Generally the aqueous concentrations of DBT and TBT measured in June were higher than in September. This can result from the typical spring activities like hosing operations and launching of the yachts .
Integrated Water Resource Management for Important Deep European Lakes and their Catchment Areas EUROLAKES D10: Impact of Contaminants Figure 10-8: Sampling Locations in Lake Geneva [BECKER et al 1992] FP5_Contract No.: EVK1-CT1999-00004 Version: 4.0 Date: 25/07/01 File: D10-vers.4.0.doc Page 77 of 136 All water and sediment samples contained more TBT than DBT suggesting that degradation takes place assuming that the primary input of butyltin to these areas is from TBT-based antifouling paint. The organotin levels in water were lower than in sediment, which confirms that they appear to concentrate there. The natural site showed concentrations below those observed in the marinas, but nevertheless organotin compounds could be detected. This indicates that the contamination extends outside the marinas onto the banks of Lake Geneva. The possibility that other important TBT sources exist seems improbable. TPT has been detected in sediments of each location but it was always present at lower concentrations than TBT [BECKER et al 1992]. The measurements showed that the molluscs contained high levels of organotins, especially those collected in Swiss ports (Table 10-4). At Port d’Ouchy / Lake Geneva TBT was found in mussels in mean annual values (Jahresmittelwerte) of about 24 – 35 mg/kg dry weight. During the measuring period between 1990 – 1993 no reduction of the TBT concentrations at Lake Geneva could be recognised The study of [BECKER et al 1992] indicates an important organotin contamination of Lake Geneva marinas, which has reached a critical level for the most sensitive species. A study of [BECKER-VAN SLOOTEN AND TARRADELLAS, 1994] was designed to assess the effects of the new Swiss law. The tributyltin concentrations have been measured in the water of one station of Lake Geneva marina between May 1990 and October 1993. The maximum values with more than 700 ng/l have been measured in spring although - according a survey - 82 % of the boats staying in the water the whole year. Because of that it can be conjecturable that metabolism, sorption to particles and sedimentation having an influence to the reduction of the concentrations during the winter time. In general, concentrations rise in summer when the pleasure boat activities are most important and decrease in autumn. The organotin concentrations of Lake Geneva marina sediment did not decrease between 1990 and 1993. The sediment concentra-
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D10: Impact of Contaminants - Hydromod

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