| Budget Amount *help |
¥25,740,000 (Direct Cost: ¥19,800,000、Indirect Cost: ¥5,940,000)
Fiscal Year 2014: ¥7,410,000 (Direct Cost: ¥5,700,000、Indirect Cost: ¥1,710,000)
Fiscal Year 2013: ¥7,280,000 (Direct Cost: ¥5,600,000、Indirect Cost: ¥1,680,000)
Fiscal Year 2012: ¥11,050,000 (Direct Cost: ¥8,500,000、Indirect Cost: ¥2,550,000)
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| Outline of Final Research Achievements |
The initial value for iodine derived from past marine sediments is said to be 1.5×10-12. However, when seaweed samples of known collection date, which were stored in the Hokkaido University Museum, were dated, values lower than 1.5×10-12 were obtained from pre-World War Two samples. This suggests that the initial value that a sample should have may have been overestimated because of emission and environmental pollution with artificial iodine 129 released through nuclear tests since 1945, and other sources.
The 129I /127I ratios in algae samples collected in the pre-nuclear era were 10-13 - 10-12, whereas the ratio measured for present algae sample was more than 10-10, thus showing that the 129I /127I ratio in post-nuclear-era algae was 100 - 1000 times as high as that of pre-nuclear-era algae. This drastic increase in the 129I /127I ratio in the algae was attributed to human activity.
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