Monitoring and Prediction of Tributyltin in the Elizabeth River and Hampton Roads, Virginia

Tributyltin (TBT) concentrations were measured in the Elizabeth River and Hampton Roads regions of Virginia 13 times at 9 stations over a 21-month period. Concentrations of TBT were highly variable over the study period suggesting intermittent kilogram cfaantity inputs from commercial drydocks or other sources. In general, concentrations were low in the Hampton Roads/Naval Station area (<10 ng TBT/l), increasing up-river to maximum levels in the vicinity of a commercial shipyard and then decreasing further up-river. Highest levels were observed during December, 1985 (mean river concentration of 87 ng/l), while lowest values were observed in June, 1986 (mean TBT concentration 2 ng/l). Dynamic Estuary Model (DEM) results predict TBT concentrations at/or below 1 ng/l in Hampton Roads and generally less than 25 ng/l in the Elizabeth River based on estimated TBT releases from hulls and drydocks in the vicinity of Hampton Roads and Elizabeth River. These are generally consistent with measured concentrations. Intermittent higher concentrations in the Elizabeth River suggest that improved commercial drydock cleanup procedures would reduce the flux of TBT into the estuary.