Organotin and Irgarol-1051 contamination in Singapore coastal waters

The seas surrounding Singapore are principally utilized by the shipping industry but are now also increasingly used for a variety of other purposes, including desalination for supplies of drinking water and intensive aquaculture of food fish. While stringent environmental pollution standards are in place for industrial effluents, there is currently no legislative control over pollution from antifouling paints in Singapore. In this study, the concentrations of toxic antifouling agents tributyltin (TBT), triphenyltin (TPhT) and Irgarol-1051 (2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine) were determined from seawater obtained from 26 locations along and off the coast of Singapore in October and November 2000. These compounds were isolated by liquid-liquid extraction derivatized under controlled microwave heating and quantified by gas chromatography-mass spectrometry. TBT concentrations in seawater ranged between 0.43 and 3.20 μgl^-1 with a mean value of 1.40±0.60 μgl^-1. The mean values of DBT and MBT were 1.07±0.80μgl^-1 and 0.34±0.50μgl^-1 respectively, while TPhT concentrations of up to 0.40 μgl^-1 were found. Monophenyltin and diphenyltin were not detected in all samples analysed. Irgarol-1051 was found to be present at concentrations of between 3.02 μgl^-1 and 4.20 μgl^-1 in seawater with a mean value of 2.00±1.20μgl^-1.