Distribution and Fate of Organotin Compounds in Japanese Coastal Waters

摘要

In order to elucidate the details of both the distribution and fate of organotin compounds (OTs) in the costal ecosystem, the concentrations of butyltin compounds (BTs) and phenyltin compounds (PTs) were determined in seawater, sediment and blue mussels Mytilus galloprovincialis collected in Maizuru Bay, Japan. The concentrations of tributyltin (TBT) in seawater, sediments and mussels ranged from 3.9 to 27 ng l~(-1), from 1.2 to 19 ng g~(-1) dry wt and from 0.77 to 11 ng g~(-1) wet wt, respectively. Although the levels of TBT in seawater, sediments and mussels from Maizuru Bay were lower than those reported previously at other sites in Japan, the levels can still be toxic to susceptible organisms. Trace amounts of PTs were also found in seawater, sediment and mussel samples, indicating that there is a slight input of triphenyltin (TPT) into the seawater in the bay at present. The highest TBT concentration in seawater among all sites measured in the bay was found near a glass factory, and the lowest concentrations were observed at the center of the bay. The highest concentration of TBT in sediment was detected near a shipyard. In mussels, a high concentration of TBT was detected near a cement plant and timberyard. These results indicate that the major sources of contamination of OTs in the bay are considered to be from those facilities and ships. The proportion of TBT in seawater and mussels showed that, of total BTs, it was the predominant compound at most sites. These results suggested that there is a continuous input of TBT into the seawater and thereafter an accumulation of TBT in mussels due to their low metabolic capacity to degrade TBT. In sediment, the proportion of monobutyltin (MBT) was the highest of BTs at most sites. This could reflect a previous contamination by TBT used before the regulation of its usage in the bay.