In 1990 the Dutch government banned the use of tributyltin-containing
antifouling paint for ships up to 25 m long. Concentrations of dissolv
ed (<0.45 mum) tributyltin and its degradation products di- and mono-b
utyltin were determined in six selected marinas during three consecuti
ve years with a frequency of five times a year, starting in 1990. The
highest butyltin concentrations were found in Scharendijke located in
the salt-water lake Grevelingen: up to 2500 ng dm-3. In tidal-water ma
rinas butyltin concentrations were in the order of 50-300 ng dm-3, dep
ending on the boating and dredging activity. In some marinas higher bu
tyltin concentrations were found during the summer period, probably in
dicating the illegal use of tributyltin-containing antifouling paints.
No clear trend of decrease in dissolved tributyltin concentrations in
the different marinas has been found. Due to the equilibrium between
the butyltins dissolved in the water and the butyltins adsorbed onto t
he sediment, water concentrations will remain more or less constant.