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Katahira, Kenshi*; Moriwaki, Hiroshi*; Ishitake, Miho*; Kokubu, Yoko; Yamazaki, Hideo*; Yoshikawa, Shusaku*
Soil and Sediment Contamination, 22(8), p.1003 - 1012, 2013/07
Times Cited Count：1 Percentile：2.80(Environmental Sciences)The objective of this study was to reveal historical changes in environmental pollution, including the influence of the Nagasaki atomic bomb, based on heavy metal concentrations in sediment core samples. Lead isotope ratios were used to determine the sources of Pb. A sediment core was sampled from a reservoir about 3 km east of the hypocenter of the Nagasaki atomic bomb. It was reported in a previous study that this sediment core contained high activities of 
Pu and 
Cs at the 1945 layer as a result of the Nagasaki atomic bomb. Concentrations of heavy metals and the Pb isotope ratios in sediments were measured using ICP-MS. The results show a spiked peak in the Pb concentrations in the same layer as that of the Pu and Cs. It is thought that the spiked peak is due to the loading of Pb by the Nagasaki atomic bombing, and this is supported by further results showing that the Pb isotope ratios in this layer were different from those in other layers.
Yamazaki, Hideo*; Yoshikawa, Shusaku*; Kokubu, Yoko
Reametaru Binran, 3, p.661 - 663, 2010/12
no abstracts in English
Cs released from Nagasaki atomic bomb in sediment of Nishiyama reservoir at NagasakiKokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Yamazaki, Hideo*; Yoshikawa, Shusaku*; Nagaoka, Shinji*; Mitamura, Muneki*; et al.
Journal of Environmental Radioactivity, 99(1), p.211 - 217, 2008/01
Times Cited Count：20 Percentile：40.82(Environmental Sciences)In a sediment core of Nishiyama reservoir at Nagasaki, depth profiles of 
Pu/
Pu ratio, Pu and Cs concentrations were determined. Sediments containing plutonium and Cs, which were fallout deposited immediately after a detonation of Nagasaki atomic bomb, were identified in the core. Observed below the sediments were macroscopic charcoals, providing evidence for initial deposit of the fallout. This is the first entire depositional records of plutonium and Cs released from the Nagasaki atomic bomb together with those from atmospheric nuclear tests.
Kokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Yamazaki, Hideo*; Yoshikawa, Shusaku*
Journal of Radioanalytical and Nuclear Chemistry, 273(1), p.183 - 186, 2007/07
Times Cited Count：7 Percentile：46.14(Chemistry, Analytical)no abstracts in English
Cs found in the surface soils of Nagasaki, JapanKokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Yamazaki, Hideo*; Mitamura, Muneki*; Yoshikawa, Shusaku*
Journal of Geosciences, Osaka City University, 50, p.7 - 13, 2007/03
no abstracts in English
Kokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Yamazaki, Hideo*; Yoshikawa, Shusaku*
KEK Proceedings 2006-5, p.36 - 40, 2006/11
no abstracts in English
Kokubu, Yoko; Magara, Masaaki; Usuda, Shigekazu; Shinohara, Nobuo; Yamazaki, Hideo*; Yoshikawa, Shusaku*; Murakami, Akiko*; Tsujimoto, Akira*; Nagaoka, Shinji*
no journal, ,
Depth profiles of concentration of Pu and Pu/Pu ratio in the cores collected from the center of the Nagasaki Bay were determined to find depositional records of plutonium released from Nagasaki atomic bomb and other nuclear tests. The ratio in sediment at the depth of about 50 cm was higher than that of the global stratospheric fallout, which might show that the plutonium has come from the nuclear tests carried out around the Marshall Islands. Deposition of plutonium from the Nagasaki atomic bomb will be also reported in the presentation.
Kokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Yoshikawa, Shusaku*; Yamazaki, Hideo*; Nagaoka, Shinji*
no journal, ,
no abstracts in English
Takasaka, Yuiko*; Katahira, Kenshi*; Moriwaki, Hiroshi*; Yamazaki, Hideo*; Kokubu, Yoko; Yoshikawa, Shusaku*
no journal, ,
Metal concentrations and lead isotope ratios in a bottom sediment core from Nagasaki-bay in Japan were measured by ICP-MS following the microwave extraction method. Before 1920s, metal concentrations in the sediment core samples were low and lead isotope ratios were near those of Japanese lead ore. From the middle of the 1930s, environmental pollution by heavy metals would become visible around Nagasaki-bay because the metal concentrations in the sediments increased and lead isotope ratios were changing. Spiked peaks for several metals in the sediment core samples were observed around 1960 when industry was developed rapidly. The amount of heavy metals released to the environment would have decreased by the law for the environmental pollution enforced in 1976. In this way, metal concentrations and lead isotope ratios in sediment core reflected the activations of industry and could reveal environmental changes for 100 years around Nagasaki-bay.
Yamazaki, Hideo*; Kawashima, Asami*; Kokubu, Yoko; Nagaoka, Shinji*; Tsujimoto, Akira*; Murakami, Akiko*; Yoshikawa, Shusaku*
no journal, ,
no abstracts in English
Kokubu, Yoko; Magara, Masaaki; Sakurai, Satoshi; Usuda, Shigekazu*; Kimura, Takaumi; Yamazaki, Hideo*; Yoshikawa, Shusaku*; Nagaoka, Shinji*
no journal, ,
Plutonium isotopes were released from Nagasaki atomic bomb which exploded on August 9, 1945. The isotopes are interesting in research on environmental radioactivity, because evident information of the plutonium release provide opportunities to simplify understanding of environmental behavior of Pu. The Nagasaki area is one of the oldest areas that were contaminated with the artificial Pu in the world. As the isotopic composition of Pu depends on its origin, Pu/Pu ratio is a useful tool for the identification of the source of Pu. This paper is intended to report the Pu/Pu ratios in sediments and surface soils and distribution of the Pu from the atomic bomb.
Kokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Yoshikawa, Shusaku*; Yamazaki, Hideo*
no journal, ,
no abstracts in English
Kokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Murakami, Akiko*; Inoue, Jun*; Yoshikawa, Shusaku*; Yamazaki, Hideo*; et al.
no journal, ,
no abstracts in English
Kokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Yoshikawa, Shusaku*; Yamazaki, Hideo*; Nagaoka, Shinji*
no journal, ,
no abstracts in English
Cs derived from Nagasaki atomic bomb; The Sedimentation in Nishiyama reservoir for the last 60 years and the distribution in surface soil at presentKokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Yamazaki, Hideo*; Yoshikawa, Shusaku*; Nagaoka, Shinji*
no journal, ,
In order to determine sedimentation of plutonium and Cs derived from Nagasaki atomic bomb for the last 60 years, we measured Pu/Pu ratio and Pu and Cs concentration in a sediment core collected at Nishiyama reservoir in Nagasaki city. A layer where plutonium and Cs deposited immediately after the detonation was specified in the core. Even at present, the plutonium and Cs from the atomic bomb are continuously being deposited together with those of the atmospheric nuclear tests. We also measured the ratios in soils collected at eastern part of Nagasaki prefecture and Kumamoto prefecture and so on to determine the detailed distributions of the plutonium. The ratios in soils collected in the Shimabara peninsula, Kumamoto city and Aso city were relatively lower than value of global fallout from atmospheric nuclear tests. It indicates that the atomic bomb plutonium was deposited between 2 km and about 100 km east from the hypocenter.
Yamazaki, Hideo*; Bessho, Keisuke*; Nishida, Hironori*; Yoshikawa, Shusaku*; Murakami, Akiko*; Tsujimoto, Akira*; Fujiki, Toshiyuki*; Kokubu, Yoko; Magara, Masaaki; Nagaoka, Shinji*
no journal, ,
no abstracts in English
