| Budget Amount *help |
¥10,100,000 (Direct Cost: ¥10,100,000)
Fiscal Year 1999: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1998: ¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 1997: ¥5,000,000 (Direct Cost: ¥5,000,000)
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| Research Abstract |
Organochlorine (Ocs) and butyltin residues (BTs) were detected in deep-sea and shallow water organisms collected from Suruga Bay, Japan. Among Ocs, residue levels of PCBs (polychlorinated biphenyls) were the highest in deep-sea organisms with upto 2800 ng/g lipid wt. Total BTs concentrations in deep-sea organisms were found with 980 ng/g wet wt at a maximum levels. Residue levels of Ocs in both deep-sea and shallow water organisms from Suruga Bay were lower than those in industrialized areas like Tokyo Bay, whereas residue levels of BTs were comparable or higher. These facts clearly indicate the expansion of BTs pollution in deep-sea ecosystems. Interestingly, TBT (tributyltin) as a parent compound of BTs was predominant in deep-sea organisms, suggesting ,a fresh input of TBT into the deep-sea environment.
Ocs and BTs residues were also determined in mesopelagic myctophid fishes collected from the western north Pacific, in order to elucidate the contamination status, accumulation patter
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ns and distribution. Among Ocs, concentration levels of PCBs and DDTs (DDT and its metabolites) were the highest in myctophids (at maximum concentrations of 370 ng/g and 310 ng/g fat wt, respectively). CHLs (chlordane compounds) or HCHs (hexachlorocyclohexanes) were the next abundant Ocs and HCB (hexachlorobenzene) was the lowest. The maximum concentration of total BTs in fish was found with 46 ng/g wet wt. Concentrations of PCBs, CHLs and BTs were lower in oceanic myctophids than those in Japanese coastal waters. The residue pattern of Ocs and BTs showed a specific trend according to diet vertical migration types of myctophids. Relatively high concentrations of PCBs, DDTs and CHLs were found in non-migratory species living in deeper waters, whereas concentrations of HCHs, HCB and BTs were high in migratory species, which migrate upto the upper 100 m at night for feeding. These patterns can influence the vertical distributions of Ocs and BTs in the subarctic and transitional waters of the western North Pacific, where intrusion of water-mass from the Okhotsk Sea has been suggested. This hypothesis can be supported by the differences in DDT composition among myctophids ; I.e. Higher proportions of p, p-DDT in non-migratory mesopelagic fish than in migrants. Temporal variation in the residue level and composition of Ocs found in myctophids indicated a significant recent decrease in the input of DDTs into the marine environment while HCHs decline at a slower rate. Less
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