In-situ partitioning of butyltin compounds in estuarine sediments

Abstract

The in-situ solid/pore-water partitioning of tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) was determined for an estuarine sediment profile collected from a commercial marina. Total butyltin levels exceeded sediment quality guideline values, and were 2208750 ¼g/kg for TBT, 1505450 ¼g/kg for DBT and 1304250 ¼g/kg for MBT. Pore-water butyltin concentrations ranged from 0.05 to 2.35 ¼g/l for TBT, 0.073.25 ¼g/l for DBT, and 0.050.53 ¼g/l for MBT. The partitioning of butyltin compounds between the sediment solid-phase and pore-water was described by an organic carbon normalised distribution ratio (DOC). The observed DOC values were similar for TBT, DBT and MBT, and were 105106 l/kg. Values for the Butyltin Degradation Index (BDI) were larger than 1 at depths greater than 10 cm below the sediment/water-column interface. This indicates that substantial TBT degradation has occurred in the sediments, and suggests that natural attenuation may be a viable sediment remediation strategy.