Butyltin compounds in marine sediments : sorption and BC-inclusive models of butyltin compounds

Abstract

TBT has been widely used for decades as the dominant composition of antifouling paints. The toxicity of TBT on aquatic life is very serious and many studies have shown that TBT can be lethal to aquatic organisms at quite low concentration. Imposex phenomena have been detected on some organisms such as dogwhelks and snails, which is an important reason for the sterility of some groups of organisms. TBT shows a strong tendency of bioaccumulation, which can be a threat to both aquatic organisms.

TBT can be broken down to less toxic butyltin compounds DBT and MBT mainly through biodegradation. It is a complicated process and difficult to control. But it is the most effective way to degrade TBT. As the metabolic substances of TBT, it is still necessary to pay attention to DBT and MBT. Sorption is an appropriate way to reduce the concentration of TBT as well. In this study, POM was used to do the measurement of organotin compounds in spiked artificial seawater. The sediment sample, from Hovedøya harbour, Oslo was extracted to find how much TBT, DBT and MBT there. The concentration of three compounds indicated a good degradation condition in the harbour.

Sorption models with BC were run using the concentration of three butyltin compounds, TBT, DBT and MBT. The results implied a strong sorption ability of BC to hydrophobic organic matter. With the increasing water concentration, the sorption went down. BSAF values were calculated with BC models. BSAF values considering of BC were apparently lower than those without BC, which indicates that BC could be a good sorbent for these three compounds, especially for TBT. However, the water concentration of TBT in Hovedøya harbour was 0.0137 ug/l that was not an ideal situation for BC sorption. DBT and MBT are more hydrophilic than TBT, BC sorption will not be so effective.