2023 Fiscal Year Final Research Report
Evaluation of radiocesium bioavailability in forest soils considering spatial heterogeneity
| Project/Area Number |
20K19951
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 63010:Environmental dynamic analysis-related
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| Research Institution | University of Tsukuba |
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Principal Investigator |
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | 選択流 / 人工降雨実験 / 染料トレーサー / 放射性セシウム / 深度分布 / 下方移行 |
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| Outline of Final Research Achievements |
It is reported that the deposited Cs-137 due to the Fukushima Daiichi Nuclear Power Plant accident has a very high spatial heterogeneity especially in forests. In this study, we focused on the preferential flow in soil as its factor, and conducted an artificial rainfall experiment using a dye tracer and physical and chemical analyses of soil samples.
As results of the artificial rainfall experiment, the dispersion (variability) of Cs-137 concentration in the dyed area was significantly larger than that in the unstained area, and also the concentration tended to be higher. Especially at 10-15 cm depth, there was a positive correlation between Cs-137 concentration and saturated hydraulic conductivity and porosity, and a negative correlation between Cs-137 concentration and bulk density. The similar trends were shown for the exchangeable Cs-137, indicating that the spatial heterogeneity and bioavailability of Cs-137 was enhanced by preferential flow, as initially hypothesized.
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| Free Research Field |
土壌環境化学
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| Academic Significance and Societal Importance of the Research Achievements |
福島第一原子力発電所事故の被災地における林業復興を進める上で、森林のCs-137動態の将来予測が求められている。しかしながら、森林土壌内のCs-137の分布は空間的不均一性が非常に高く、樹木による吸収量や土壌中の下方移行モデルの予測精度を低下させているという問題があった。本研究では、この空間的不均一性を生み出す要因として選択流の影響を明らかにしたものであり、種々のモデル精度向上に資することが期待される。
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