Source identification and apportionment of tributyltin compound in an enclosed bay including a shipyard

Abstract

To identify tributyltin (TBT) input sources and pathways in an enclosed bay which includes a large shipyard, multimedia monitoring (sea water, river water, effluents, sediments, sediment cores, biota and ship hulls) has been conducted. Exceptionally elevated TBT, dibutyltin and monobutyltin concentrations were found in all the matrices analyzed near shipyard. Their concentrations steeply decreased towards off coast. Vertical profile of TBT concentrations in age dated sediment cores revealed that increase of TBT is corresponding to gross tons of ships built in the shipyard during the past two decades, but apparent decreasing trend from the late 1990s. Sediment toxicity test using Microtox and amphipod demonstrated extreme toxicity in the site very close to a shipyard effluent outlet, and an obvious decreasing trend towards off coast. These results indicate that the shipyard plays an important role to input toxic TBT compound to receiving waters and environments. Emission scenario was constructed in the study area based on MAM-PEC model. A shipyard was estimated to contribute up to 43% of TBT loading in the study area.