2020 Fiscal Year Final Research Report
Elucidation of Accumulation Mechanism of Radiocerium in Stem wood Based on Material Circulation in Trees
| Project/Area Number |
17K00635
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Environmental risk control and evaluation
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| Research Institution | Utsunomiya University |
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Principal Investigator |
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| Project Period (FY) |
2017-04-01 – 2021-03-31
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| Keywords | 放射性セシウム / 樹木 / 物質循環 / 集積・蓄積 / 辺材 / 心材 |
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| Outline of Final Research Achievements |
This study was conducted mainly in the northern part of Tochigi Prefecture.
As a result of examining the variation of Cs -137 concentration in the stem,especially the radial movement of the Japanese cedar, Cs -137 accumulated in the heartwood, and the movement speed in the xylem by the diffusion depended on the tree body. In addition, as a result of planting each 3 individuals of 10 clones of cedar produced in the polluted soil by the single tree mixing method, the concentration of branches and leaves was affected by the pollution level of the soil rather than the clone.
On the other hand, in Quercus serrata （Japanese oak）, the original wood for shiitake, Cs -137 did not tend to accumulate in heartwood, and the concentrations of bark and wood (core and sapwood) did not change significantly after 2016. The authors measured Cs -137 of fruiting body of shiitake cultivated in open field using collected raw wood, and evaluated its usability as food.
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| Free Research Field |
森林資源保全学
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| Academic Significance and Societal Importance of the Research Achievements |
本研究における調査は、主に栃木県県北で実施された。
① スギは、建築用や木質バイオマス用と多様な用途があり、日本において重要な造林樹修である。スギ樹幹木部の心材は、Cs-137を集積・蓄積する傾向があり、これはカリウム含有量と連動している。心材にCs-137が存在することで、芯持ち柱として使用される場合、木材の内部にCs-137を封印することになり、外部に放出される放射線がかなり低減される。このことは、使用に際しての安全性の担保になると考えられる。
② 現地のコナラで露地栽培された生シイタケのCs-137濃度は、事故後10年において、全てのサンプルで規制値100Bq/kg以下を示した。
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