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Be deposition in Hokuriku, JapanYoshida, Keisuke; Kato, Shingo; Okuyama, Shinichi; Nakano, Masanao; Ishimori, Yuu; Uchida, Kengo*; Inoue, Mutsuo*
Hoken Butsuri (Internet), 60(1), p.40 - 47, 2025/04
Monthly Be depositions were examined at four sites in Hokuriku, Japan, from 1992 to 2021. The amounts of Be depositions in Hokuriku from October to March differed locally: Depositions at Kanazawa were high (4400 Bq/m
), a site along the foot of the mountains. Be depositions in the plain of Fukui city, along Wakasa Bay, and along the coast of the Noto Peninsula (3300, 2800, and 2500 Bq/m, respectively) were equivalent to those of other areas along the coast of the Sea of Japan. The local variation in Be depositions in Hokuriku is predominantly ascribed to precipitation, topographic feature, and Be concentrations.
Yoshida, Keisuke; Kato, Shingo; Okuyama, Shinichi; Ishimori, Yuu; Inoue, Mutsuo*
Journal of Nuclear and Radiochemical Sciences (Internet), 24, p.1 - 12, 2024/08
Kato, Shingo; Yoshida, Keisuke; Inoue, Mutsuo*; Yamashita, Masahiro; Okuyama, Shinichi; Ishimori, Yuu
no journal, ,
no abstracts in English
Hagiwara, Hiroki; Yoshida, Keisuke; Ishimori, Yuu; Nakano, Masanao; Tsunokawa, Shoji*; Yamashita, Masahiro; Inoue, Mutsuo*; Ochiai, Shinya*
no journal, ,
no abstracts in English
Be depositions in Hokuriku, JapanYoshida, Keisuke; Kato, Shingo; Uchida, Kengo*; Yamashita, Masahiro; Okuyama, Shinichi; Inoue, Mutsuo*
no journal, ,
In winter, Be deposition profile shows wide variation in Hokuriku region. Temporal and regional variations of Be deposition data during 30 years (Apr. 1991 to Mar. 2021) were analyzed and material transport mechanisms from arctic region were studied. Due to pressure pattern around Japan in winter and inhomogeneous precipitation in Hokuriku region caused by topography, characteristic seasonal variation was found and highest Be deposition was observed in mountainous area in Kanazawa City. In addition, the period of high Be deposition observed approximately agreed with that of minimum sunspot number or maximum precipitation. Therefore, sunspot number and precipitation affect temporal variations of Be deposition.
Be and 
Na deposition in the Hokuriku region in winterYoshida, Keisuke; Tsunokawa, Shoji; Umeda, Masayuki; Yamashita, Masahiro; Nakano, Masanao; Ishimori, Yuu; Inoue, Mutsuo*
no journal, ,
no abstracts in English
Yoshida, Keisuke*; Inoue, Mutsuo*; Minakawa, Masayuki*; Nakano, Yusuke*; Kofuji, Hisaki*; Otosaka, Shigeyoshi; Kiyomoto, Yoko*; Shiomoto, Akihiro*; Hamajima, Yasunori*; Yamamoto, Masayoshi*
no journal, ,
The authors have developed an analytical method for Th-228, Ra-226 and Ra-228 measurements in seawater using an ultra-low background 
-ray detector. In this study, the authors measured the three radionuclides in surface seawater obtained from 16 stations in the Japan Sea, East China Sea and Okhotsk Sea. Concentrations of Ra-228 and Th-228 in surface waters in the southern Japan Sea were lower than those in the northern regions. Considering that the Th-228/Ra-228 activity ratios were not different between the northern and southern regions of the Japan Sea, we could conclude that (1) input of terrestrial materials from the East China Sea has not affected the distribution of the radionuclides in the Japan Sea, and (2) the efficiency of scavenging was not different between the regions.
Na and Be depositions in Tsuruga cityYoshida, Keisuke; Kato, Shingo; Inoue, Mutsuo*; Ishizuka, Akihiro; Okuyama, Shinichi
no journal, ,
Na is observed for environmental monitoring of Monju fast breeder reactor because Monju reactor contains Na in primary coolant. But Na is produced in upper atmosphere, therefore, Na is detected in assembled deposition sample. To increase accuracy of environmental monitoring, it is necessary to understand transport and supply process of Na and Be depositions from high latitude region where a lot of Na is produced. We collect deposition samples at Tsuruga city to measure Na and collect Be deposition data in 5 sites in Fukui prefecture and Ishikawa prefecture. Because Na and Be shows good correlation, Na have same behavior with Be. Be deposition is maximum at Kanazawa city and minimum at Shika town, but Be deposition is maximum in Winter season at all sites. Be deposition and precipitation shows correlation. From the above, Winter monsoon transport Be and Na from high latitude region and precipitation provide these nuclides to ground surface at Tsuruga city. The deference of Be deposition in Winter season is likely owing to height of mountain and distance of sampling sites.
