In Situ Adsorptlon and Desorption of Butyltin Compounds from Pearl Harbor, Hawaii Sediment

An in situ method to determine adsorption and desorption of butyltin compounds at the sediment-water interface is described. A recirculating dome system enclosing approximately 0.8 m of sediment surface area and 100 liters of water acts as a closed system to allow periodic removal of water to document changes over time of butyltin concentrations within the system. Concentration changes over time yield adsorption and desorption rates and knowledge of both sediment and water concentrations yields partitioning coefficients. Butyltin concentrations appear to be at or near equilibrium across the Sediment-water interface in Pearl Harbor, Hawaii both before and after a large vessel was painted with TBT-containg paint. TBT did not significantly desorb from the sediment, but adsorbed at a rate of 0.57 ng TBT/cm²/day. DBT desorbed from the sediment at rates between 0.16 and 0.55 ng DBT/cm²/day. MBT adsorption or desorption trends were not statistically significant.