著者

吉川 周作 山崎 秀夫 井上 淳 三田村 宗樹 長岡 信治 兵頭 政幸 平岡 義博 内山 高 内山 美恵子

出版者

日本地質学会

雑誌

地質學雜誌 (ISSN:00167630)

巻号頁・発行日

vol.107, no.8, pp.535-538, 2001-08-15

参考文献数

20

被引用文献数

1

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The explosion of a plutonium atomic bomb over Nagasaki city took place on 9 August 1945. After the explosion, a cloud formed, which passed over the Nishiyama district, where 'black rain' fell. Thus, the Nishiyama reservoir, located approximately 3 km from the hypocenter, received the heaviest radioactive fallout from the Nagasaki atomic bomb. Sediment samples were collected from the bottom of the Nishiyama reservoir in 1999 and analyzed for their ^<137>Cs, ^<241>Am and charcoal concentrations. The stratigraphic distribution of ^<137>Cs and charcoal clearly indicate that the 'black rain' horizon is recognized in the Nishiyama reservoir sediments. The 'black rain' horizon contains anthropogenic radionuclides (^<137>Cs and ^<241>Am) and charcoal in high concentrations.