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| Masayuki Kunugi | |
| Senior Researcher | |
| Marine Research Team | |
| Global Environmental Studies Group | |
| National Institute for Environmental Studies | |
| Environment Agency | |
| 16-2 Onogawa, Tsukuba 305-0053 Japan | |
| Tel: +81-298-50-2434 Fax: +81-298-50-2569 | |
| E-mail: kunugi@nies.go.jp |
¡¡17,080,000 Yen
¡¡(FY 1999; 8,840,000 Yen)
¡¡We developed a continuous-extraction system for sampling of hazardous chemicals in seawater, suitable for mounting on a merchant vessel. By mounting this system in the ferry "Sunflower Ivory", which navigated the Seto Inland Sea from December 1998 to March 2000, we observed the concentrations of hazardous chemicals in seawater a total of 11 times and confirmed the usefulness of the system. Using these observations, we analyzed the dynamics of hazardous chemical pollution in the Seto Inland Sea. In addition, from March 1999, we began to sample the levels of hazardous chemicals in the atmosphere on the Inland Sea. We detected ¦Á-HCH and ¦Â-HCH in seawater in almost all observations. In particular, ¦Â-HCH remained at a comparatively high concentration after September 1999. The spatial and seasonal fluctuations of ¦Á-HCH concentrations were greater than those of ¦Â-HCH, and the residence time of ¦Á-HCH in seawater was short. The abundance ratio of each isomer fluctuated greatly with observation point and time. We detected ¦Á-HCH and ¦Ã-HCH in the atmosphere in all samples, but ¦Â-HCH was undetected in most samples. The concentrations of chlordanes and nonachlores in seawater were under the detection limit on over half of the observations, and the concentrations fluctuated greatly in both seawater and the atmosphere.
¡¡The high concentrations of ¦Â-HCH observed after September 1999 were caused by typhoons greatly stirring the seawater and redistributing ¦Â-HCH accumulated in the sediment. The fluctuations of ¦Á-HCH, ¦Ã-HCH, chlordane and nonachlore concentrations in seawater were correlated to the concentrations of each in the atmosphere; thus, the sea-air exchange of these chemicals seems rapid.
¡¡From these results, it is clear that frequent observations are indispensable to gain a grasp of the dynamics of marine pollution by hazardous chemicals. By observing their concentrations at various times and locations, it was possible to estimate the dominant origins of HCHs and chlordanes.
¡¡Hazardous chemicals, POPs, Spatial distribution, HCHs, VOS