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210 results on '"Takaku, Yuichi"'

4. Chemical form of volatilized iodine obtained from orchard grass (Dactylis glomerata L.).

Author

Yanai, Masumi, Kawabata, Hitoshi, and Takaku, Yuichi

Abstract

Japan's first commercial nuclear fuel reprocessing plant is expected to release radioiodine into the atmosphere, and orchard grass plants grown in the vicinity of this plant may absorb this radioiodine. In this study, we investigated the mechanism underlying the absorption and volatilization of iodine in the leaves of orchard grass. Our findings suggest that iodine can be transferred from the leaves of this grass to the atmosphere via two routes: direct volatilization and absorption followed by volatilization. Previous studies on rice and oats also show that iodine can be absorbed by the roots and volatilized from the plant's body. Although orchard grass absorbs iodine via the leaves, the chemical form of volatilized iodine may differ from that absorbed via the roots. We applied a NaI solution to the leaves of orchard grass and analyzed the volatilized iodine. The experimental results showed that the iodine was volatilized as methyl iodide. [ABSTRACT FROM AUTHOR]

Published
2024
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5. Absorption and translocation to fruit for cesium applied on apple tree leaf surface.

Author

Kawabata, Hitoshi, Yanai, Masumi, Takaku, Yuichi, and Hisamatsu, Shun'ichi

Abstract

We investigated the behavior of stable Cs+ ions contained in droplets applied directly on the leaf surfaces of plumleaf crab apple trees (2–3 years old Malus domestica 'Alps Otome') at three different fruit growing stages: before bearing fruit, early fruit development and late fruit development stages. Most of the Cs was rapidly transferred from the leaf surfaces into the applied leaves after application, and then gradually transferred to the fruit through the branches. The mean proportion of Cs transferred to fruit by harvest time ranged from 11 to 30% not directly depending on the fruit growing stages. Cs absorption from leaf surfaces was faster at early and late fruit development stages than before bearing fruit stage, and Cs transfer from leaf surfaces to the fruit was faster as the fruit growing stage progressed. To describe the transfer of Cs, we constructed a compartment model using the datasets of obtained for each fruit growing stage. However, it did not well reproduce the measured values, showing that further studies are necessary. [ABSTRACT FROM AUTHOR]

Published
2024
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31. ICP-MS Applications

Author

Morton, Jackie, primary, Quinn, Zoë A., additional, Baranov, Vladimir I., additional, Tanner, Scott D., additional, Spence, Bill, additional, Wray, David, additional, Takaku, Yuichi, additional, Collard, Jean-Marie, additional, and Kishi, Yoko, additional

Published
2009
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37. ²⁴⁰Pu/²³⁹Pu and ²⁴²Pu/²³⁹Pu atom ratios of Japanese monthly atmospheric deposition samples during 1963–1966

Author

Ohtsuka, Yoshihito, Aoyama, Michio, Takaku, Yuichi, Igarashi, Yasuhito, Hattori, Michinari, Hirose, Katsumi, and Hisamatsu, Shun’ichi

Abstract

Global fallout plutonium isotopic ratios from the 1960s are important for the use of Pu as environmental tracers. We measured the ²⁴⁰Pu/²³⁹Pu and ²⁴²Pu/²³⁹Pu atomic ratios of monthly atmospheric deposition samples collected in Tokyo and Akita, Japan during March 1963 to May 1966. To our knowledge, our results represent the first data measured for actual atmospheric deposition samples collected continuously during the 1960s. Both atomic ratios increased rapidly from March 1963 to June 1963, followed by a gradual increase until September 1963. Then, both ratios declined with a half-life of approximately 5.6 months. The observed temporal changes of the ratios were likely caused by the upper-stratospheric input of nuclear debris from high-yield atmospheric nuclear weapon testing during 1961–62, followed by its downward transport to the troposphere.

Published
2019

38. ²⁴⁰Pu/²³⁹Pu and ²⁴²Pu/²³⁹Pu atom ratios of Japanese monthly atmospheric deposition samples during 1963–1966

Author

90343897, Ohtsuka, Yoshihito, Aoyama, Michio, Takaku, Yuichi, Igarashi, Yasuhito, Hattori, Michinari, Hirose, Katsumi, Hisamatsu, Shun’ichi, 90343897, Ohtsuka, Yoshihito, Aoyama, Michio, Takaku, Yuichi, Igarashi, Yasuhito, Hattori, Michinari, Hirose, Katsumi, and Hisamatsu, Shun’ichi

Abstract

Global fallout plutonium isotopic ratios from the 1960s are important for the use of Pu as environmental tracers. We measured the ²⁴⁰Pu/²³⁹Pu and ²⁴²Pu/²³⁹Pu atomic ratios of monthly atmospheric deposition samples collected in Tokyo and Akita, Japan during March 1963 to May 1966. To our knowledge, our results represent the first data measured for actual atmospheric deposition samples collected continuously during the 1960s. Both atomic ratios increased rapidly from March 1963 to June 1963, followed by a gradual increase until September 1963. Then, both ratios declined with a half-life of approximately 5.6 months. The observed temporal changes of the ratios were likely caused by the upper-stratospheric input of nuclear debris from high-yield atmospheric nuclear weapon testing during 1961–62, followed by its downward transport to the troposphere.

Published
2019

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