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[D-2.2 Uptake of Pollutants by Marine Zooplankton and their Behavior in the Marine Food-Chain]

[Contact Person]

Takejiro Takamatsu
Section Director, Soil Science Section
Water and Soil Environment Div., National Inst. for Environmental Studies
Environmental Agency
16-2 Onogawa, Tsukuba, Ibaraki 305 Japan
Phone +81-298-50-2469, Fax +81-298-51-4732

[Total Budget for FY1993-1994]

21,618,000 Yen (FY1994 11,796,000 Yen)

[Abstract]

　Zooplankton, fry and pelagic eggs were collected from the Japan Sea, the Pacific Ocean, and some polluted bays including Tokyo, Osaka and Fukuoka Bays. Thirty-seven elements were analyzed in the samples by neutron activation and ICP-AES analyses. Although the zooplankton sometimes contained somewhat high concentrations of Al, Si, Sc, Ti and Fe resulted probably from the inorganic impurities incorporated in the digestive organs, approximate concentrations of elements in the planktonic tissue were estimated by the selective HNO₃-digestion of the samples. Concentrations of several major elements(e.g. P) was approximately constant regardless of variation in body weight of zooplankton(0.002-16.0mg), while those of heavy metals slightly increased with decreasing the weight. When the MKT-plot(plot of τ_R x CF_sw vs. CF_sw; τ_R: mean oceanic residence time of elements, CF_sw: concentration factors of elements from seawater to the sanlples) was applied to the plankton, slopes of the plots were clearly higher in the samples from the bays(av.=0.22) than those from the open-sea(av.=0.13), indicating the increased heavy metal contamination in the bay plankton. Slopes of the MKT-plots for fry samples were generally higher(0.12-0.30) than those for zooplankton. In addition, the slopes were much higher in the case of pelagic eggs(0.39). This may indicate the accumulation of heavy metals in fishes(zooplankton-eaters) through the marine food-chain.

[Key Words]

Zooplankton, Pollution, Heavy Metals, Marine Food-Chain