| Budget Amount *help |
¥5,330,000 (Direct Cost: ¥4,100,000、Indirect Cost: ¥1,230,000)
Fiscal Year 2014: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2013: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
Fiscal Year 2012: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
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| Outline of Final Research Achievements |
We investigated effects of Fukushima disaster in fish. Ayu were collected from Fukushima and Hiroshima in July 2013. Cesium concentrations were measured with a germanium semiconductor detector. As an index of the cesium elimination delay, Sr/Ca ratios in otoliths from the two sites were compared using laser ablation inductively coupled plasma mass spectrometry. As an index of radiostrontium contamination, beta ray emissions from the otoliths were measured using an imaging plate.
Radiocesium was not detected in Hiroshima ayu but was in Fukushima ayu (6.2 ± 3.5 Bq/Kg-wet of 134Cs plus 137Cs). No differences in Sr/Ca ratio was found between otoliths from the two sites, and otoliths did not emit beta rays. Examination of otoliths revealed that Fukushima and Hiroshima ayu grew under environments of near-identical salinity, suggesting that the former exhibited no delay in radiocesium elimination. Overall, contamination of ayu after the Fukushima nuclear power plant accident appears slight.
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