Tributyltin in seawater: speciation and octanol-water partition coefficient

Analysis of chloroform extracts of tributyltin (TBT) dissolved in seawater using nuclear magnetic resonance indicated that the equilibrium mixture was composed of tributyltin chloride, tributyltin hydroxide, the aquo complex and a tributyltin carbonato species. The species present were influenced by pH, chloride and dissolved carbon dioxide. Octanol-water partition coefficients (Kow) for tributyltin varied with salinity. The Kow values were higher by a factor of 2 than published values. This was attributed to the presence of redistribution products, notably dibutyltin. The Kow values were in agreement with published bioaccumulation measurements for tributyltin assuming partitioning processes were responsible.