Environmenral Toxicology and Chemrsfry zyxwvutsrqponm Vol zyxwvutsrqponm 12, pp i115-1i84 1993 Printed in the USA Pergamon Press Ltd zyxwvutsrqpon 0130 7268/93 $6 zyxw 00 zyxw + 00 Copyright zyxw 0 1993 SETAC DISTRIBUTIONS OF BUTYLTINS IN THE SURFACE SEDIMENT OF ISE BAY, JAPAN YOSHITAKA YONEZAWA, * t KISABURO NAKATA, 7 YOSHIKAZU MIYAKOZAWA, $ AKIKO OCHI, $ TAKAO KOWATA,$ HIROAKI FUKAWA,$ YUUJI SATO,$ SHIGEKI MASUNAGA~ and YOSHIKUNI URUSHIGAWA~ ?National Institute for Resources and Environment, 16-3 Onogawa, Tsukuba, Ibaraki, 305 Japan $International Trade and Industry Inspection Institute, 2-49-10 Nishihara, Sibuya, Tokyo, 151 Japan zyxwvu (Received 11 March 1992; Accepted 22 October 1992) Abstract-Concentrations of tri-n-, di-n-, and mono-n-butyltin (TBT, DBT, and MBT) were deter- mined for surface sediments collected from 44 sites within Ise Bay, Japan The concentrations of TBT, DBT, and MBT ranged from not detected (ND) to 0 11, ND to 0.073, and ND to 0.098 pg g-: dry sediment, respectively, excluding one site near a shipyard (TBT concentration 0.54-1.1 pg g dry sediment) The distribution patterns of the three butyltins were similar to each other. The concen- tration of TBT correlated to the organic carbon (OC) content of the sediment and did not correlate to the sediment particle size. The area with high concentration of butyltin extended from the east- ern side of the middle of the bay toward the southwest to Tsu-Matsuzaka Port. This area had a high organic content area and corresponded to the downwelling zone simulated by a baroclinic three- dimensional hydrodynamic model. Another area with high butyltin concentrations, near Yokkaich Port, was also located in the simulated downwelling zone The area near Nagoya Port, which is in the simulated upwelling zone, had low butyltin concentrations, although the amount of TBT load- ing in Nagoya Port was estimated to be several times greater than that in Yokkaichi Port The ratio of TBT to MBT decreased along the direction of surface flow from Yokkaichi Port to the middle of the bay These results suggested that the amount of the TBT loading could not explain all of the distribution of the TBT concentration in the sediment, and that tidal bay circulations, hydrodynam- ically up- and downwelling, and surface flow affected it strongly. Keywords -Butyltins Distributions Surface sediments Ise Bay Tidal flow INTRODUCTION Pollution by tri-n-butyltin (TBT) is widespread in the coastal areas, and its effects on marine or- ganisms are of great concern [l-61. In Japan, al- though the level of TBT concentration IS low, it has been reported that not only the cultivated fish and bivalves but also the fish within coastal areas accu- mulateTBT zyxwvutsr [7-151. In January 1991, the Japanese government designated 14 TBT compounds as spec- ified chemical substances whose production, import, and use are regulated. In October 1990, the govern- ment announced that antifouling paint containing TBT compounds must not be used for coastwise vessels and pleasure boats, except for aluminum- bottom ones, but that they can still be used for the bottomside of ocean liners. The use of TBT compounds for fish culture nets was given up vol- *To whom correspondence may be addressed. untarily in 1989. About 2,000 tons of TBT com- pounds (as TBT moiety) were produced in Japan in 1989. Tributyltin compounds are used as anti- foulants in paint for ship hulls (about 70%; most are copolymers of TBT- and alkyl-methacrylate) and for fishing nets (about 30%). The amounts of TBT used as preservatives or fungicides are very minimal. Numerical models simulating behaviors of TBT in the coastal areas are becoming essential tools for controlling its pollution of the aquatic environ- ments. The authors surveyed distributions and be- haviors of chlorobenzenes in Ise Bay, Japan [16,17] and have been developing a numerical model sim- ulating the behaviors based on the survey data [18]. Sources of TBT, most of them ship paint [I ,2,6], are considered as linear or area sources, whereas those of chlorobenzenes are considered as point sources along the bay coast. As types of TBT sources are quite different from those of chloroben- 1175