Measurement of Butyltins in San Diego Bay, CA: A Monitoring Strategy

A monitoring survey of butyltin concentrations was conducted in San Diego Bay in February, 1986. Intensive sampling was designed to differentiate tidal, vertical and regional variability components. Yacht harbors and marinas had by far the highest concentration of tributyltin within San Diego Bay, ranging from 0.027 to 0.235 ug/l. The lowest tributyltin concentrations, frequently below detection, were found in the southern part of the bay, where water residence time was longest. Navy berthing areas and the northern part of the bay had intermediate values, usually in the range of 0.005-0.015 ug/l. Compared to data from a 1984 baseline survey, 1986 tributyltin concentrations decreased in all regions, however, total butyltin increased slightly, suggesting accumulation of degradation products. Tide and depth were important in determing tributyltin concentration variability but the degree of effect was sample station dependent. Yacht harbors and marinas can regionally be considered a tributyltin source while the southern bay can regionally be considered a sink.