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  • 1 Institute for Environmental Sciences Department of Radioecology Ienomae 1-7, Rokkasho-mura, Kamikita-gun, Aomori-ken 039-3212 Japan
  • | 2 Institute for Environmental Sciences Department of Radioecology Department of Radioecology Ienomae 1-7 Rokkasho-mura, Kamikita-gun, Aomori-ken 039-3212 Japan
  • | 3 University of Shiga Prefecture Limnological Laboratory, School of Environmental Science Yasaka-cho 3165, Hikone-shi, Shiga-ken 522-0057 Japan
  • | 4 Shimane University Department of Material Science, Faculty of Science and Engineering Nishikawatsu-cho 1060, Matsue-shi, Shimane-ken 090-8504 Japan
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Abstract  

We investigated the distribution of aquatic plants and the absorption of radionuclides by them in the brackish Lake Obuchi, Japan, which is bordered by nuclear fuel cycle facilities. We studied 5 species of submerged plants: Zannichellia palustris, Ruppia maritima, Potamogeton pectinatus, Zostera japonica, and Z. marina. The plants contained many elements, including radionuclides. The concentrations of 238U, 137Cs, and 90Sr in Z. marina were 11.3-12.4, 0.000-0.144, and 0.151-0.202 Bq.kg-1 dw, respectively. Those in Z. japonica were 5.2-8.8, 0.000-0.267, and 0.081-0.175 Bq.kg-1 dw, respectively. The concentrations of these radionuclides in the plants tended to be higher in higher-salinity regions than in lower-salinity regions of the lake. We found a close relationship between photosynthetic activity and the absorption of stable Sr by plants in the laboratory. Salinity, illumination, and water temperature influenced the photosynthetic activity of the plants and the consequent absorption of elements.