Partitioning of selected antifouling biocides in the aquatic environment

Following a ban on the use of tributyltin in antifouling products on small boats, a number of organic booster biocides have been utilised in conjunction with copper in antifouling paints as alternative treatments. The fate of organic compounds in the aquatic environment is closely linked to their partitioning between aqueous media and sediment. In this study, experiments were designed to investigate the partitioning and sorptive behaviour of Irgarol 1051, chlorothalonil, dichlofluanid and diuron in the aquatic environment. Factorial experiments were undertaken to determine the importance of pH, particulate matter concentration and salinity to their sorption. A Mackay fugacity model was also applied. Results demonstrated that dichlofluanid had the stronger adsorption characteristics and was predicted to bind more strongly to sediments than Irgarol or chlorothalonil. Diuron exhibited the least preference for sorptive behaviour. Sorption appeared to be enhanced by increased suspended matter, whilst salinity does not seem to play a significant role in the partitioning behaviour of these biocides.