Status and Trend of Tributyltin Contamination in Sediments from a Shipyard and its vicinity

Abstract

Fisherman’s association sued a large shipbuilding industry in southern Korea for its possible adverse effects on surrounding environments and fisheries. One of suspicious pollutants to cause harmful effects on fisheries in this case is a highly toxic tributyltin (TBT) compound used in antifouling paint during shipbuilding process. Thus, an extensive survey, including multimedia monitoring (sea water, effluents, sediments, biota and ship hulls), has been conducted to identify TBT input sources and pathways. Three sediment cores were analyzed for understanding of historical trend of TBT input and its relationship with past shipbuilding activity. Mussels from pristine area were transplanted to seven sites in the study area for up to 120 days to evaluate input sources and accumulation pattern of TBT. In addition, sediment toxicity was assessed using Microtox and amphipod for toxic effects of sediment bound TBT on organisms. Exceptionally elevated TBT and its degradation products, dibutyltin and monobutyltin, concentrations were found in all the matrices analyzed near shipyard. However, 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. Two sediment toxicity tests 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. The extent of environmental impact and areas of concern are tentatively estimated based on this study.