Detection and activity of iodine-131 in brown algae collected in the Japanese coastal areas.
Iodine-131 (physical half-life: 8.04 days) was detected in brown algae collected off the Japanese coast. Brown algae have been extensively used as bioindicators for radioiodine because of their ability to accumulate radionuclides in high concentration factors. The maximum measured specific activity of (131)I in brown algae was 0.37 + or - 0.010 Bq/kg-wet. Cesium-137 was also detected in all brown algal samples used in this study. There was no correlation between specific activities of (131)I and (137)Cs in these seaweeds. The specific activity of (137)Cs ranged from 0.0034 + or - 0.00075 to 0.090 + or - 0.014 Bq/kg-wet. Low specific activity and minimal variability of (137)Cs in brown algae indicated that past nuclear weapon tests were the source of (137)Cs. Although nuclear power stations and nuclear fuel reprocessing plants are known to be pollution sources of (131)I, there was no relationship between the sites where (131)I was detected and the locations of nuclear power facilities. Most of the sites where (131)I was detected were near big cities with large populations. Iodine-131 is frequently used in diagnostic and therapeutic nuclear medicine. On the basis of the results, we suggest that the likely pollution source of (131)I, detected in brown seaweeds, is not nuclear power facilities, but nuclear medicine procedures.
Morita
Takami
T
Fisheries Research Agency, 15F Queen's Tower B, Minato Mirai Nishi-ku, Yokohama, Kanagawa 220-6115, Japan. takam@affrc.go.jp
Niwa
Kentaro
K
Fujimoto
Ken
K
Kasai
Hiromi
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Yamada
Haruya
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Nishiutch
Kou
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Sakamoto
Tatsuya
T
Godo
Waichiro
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Taino
Seiya
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Hayashi
Yoshihiro
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Takeno
Koji
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Nishigaki
Tomokazu
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Fujiwara
Kunihiro
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Aratake
Hisamichi
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Kamonoshita
Shingo
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Hashimoto
Hiroshi
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Kobayashi
Takuya
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Otosaka
Sigeyoshi
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Imanaka
Tetsuji
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D007457:Iodine Radioisotopes / Q000032:analysis*; D007564:Japan; D000459:Phaeophyceae / Q000737:chemistry*
D007457:Iodine Radioisotopes