Effect of anthropogenic thorium on formation of cloud nuclei

• Project/Area Number: 26740012
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Environmental dynamic analysis
• Research Institution: Japan Atomic Energy Agency
• Principal Investigator: Okubo Ayako 国立研究開発法人日本原子力研究開発機構, 核不拡散・核セキュリティ総合支援センター, 研究職 (70415412)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Project Status: Completed (Fiscal Year 2016)
• Budget Amount: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000); Fiscal Year 2016: ¥520,000 (Direct Cost: ¥400,000、Indirect Cost: ¥120,000); Fiscal Year 2015: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2014: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
• Keywords: 雲粒核 / トリウム同位体 / 人為的影響 / 降水試料 / 人為的活動起源 / トリウム / 降水

Outline of Final Research Achievements

To elucidate the effect of anthropogenic thorium on formation of cloud nuclei, the concentration of trace metals and thorium isotopes in rainfall sample were measured. Thorium isotope ratios (230Th/232Th) were 5-6 order of magnitude higher than the average thorium isotopes ratio in crust, fractionation of uranium and thorium in industrial process was supposed. Thorium isotope ratios were clearly different between dissolved form and particulate form, indicating thorium in rainfall sample has several origins and which have different property of dissolution in the sample.