Distribution and Origin of Organotin Species in Seawater of the Seto Inland Sea, Japan

Organotin species in seawater, collected by using a ferry between Osaka and Beppu, were determined by gas chromatography combined with inductively coupled plasma mass spectrometry after the ethylation with sodium tetraethylborate. Distributions of 9 organotin species below 1 ng Sn/l in the Seto Inland Sea were clarified for the first time. The concentrations of tributyltin (TBT) and triphenyltin (TPhT) were in the range of 0.21-1.02 ng Sn/l and 0.021.0.096 ng Sn/l, respectively. Three unknown species among them were identified as mono-, di-, and tri-octyltin species, which were used as plastic stabilizers. Butyltin and phenyltin species except for TPhT were found to occur as dissolved form, but di- and tri-octyltin species were found to occur as particular form. Principal component analysis revealed the origin of pollution at each sampling station, i.e., whether it come from antifouling paints or from plastic stabilizers.