Change of coastal environment which accompanies with human activity obtained from radioactivity in seaweed

2014 Fiscal Year Final Research Report

• Project/Area Number: 24686098
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Partial Multi-year Fund
• Research Field: Earth system and resources enginnering
• Research Institution: Hokkaido University
• Principal Investigator: OHTA TOMOKO 北海道大学, 工学(系)研究科(研究院), 助教 (30373020)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 環境放射能 / 海藻 / AMS / I-129 / 核実験 / 原子力災害

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.

Free Research Field

環境放射能