著者

吉岡 勝廣 飯田 孝夫

出版者

日本保健物理学会

雑誌

保健物理 (ISSN:03676110)

巻号頁・発行日

vol.42, no.1, pp.53-62, 2007 (Released:2010-08-05)

参考文献数

39

被引用文献数

2 4

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We compared the periodic characteristics of the atmospheric radon concentration on the land and ocean, using data simultaneously measured at Oki Island in the Sea of Japan and Matsue, which is located 70km south of the island and on the Shimane peninsula. The radon concentration was the highest in the fall at Matsue and in the winter at Oki Island and the lowest during the summer at both locations. The frequency distributions and the annual periodic variations of the arriving pathways of the air masses and these radon concentrations at Matsue and Oki Island showed the same tendency. At Matsue, the monthly average of diurnal minimum of the radon concentration was highest in the winter that was three month late from the maximum season of the monthly average of all measurements. The monthly average of radon concentration at Matsue showed the positive correlation between the monthly occurrence times of temperature inversion. The annual periodic variation of the radon concentration at Oki Island depends on the long-term variation of the distribution of arriving pathways of the air masses.

著者

吉岡 勝廣

出版者

日本エアロゾル学会

雑誌

エアロゾル研究 (ISSN:09122834)

巻号頁・発行日

vol.17, no.4, pp.267-275, 2002-12-20 (Released:2008-03-27)

参考文献数

16

著者

吉岡 勝廣 湊 進

出版者

公益社団法人 日本アイソトープ協会

雑誌

RADIOISOTOPES (ISSN:00338303)

巻号頁・発行日

vol.53, no.7, pp.427-433, 2004-07-15 (Released:2011-03-01)

参考文献数

14

被引用文献数

3 3

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To study the relation between the terrestrial γ-ray dose rate and subsurface geology, the γ-ray dose rate has been surveyed at 213 points in Okinoshima, an island situated in the Japan Sea, with a γ-ray survey meter. The results of this observation are the mean value of terrestrial γ-ray dose rate at 213 points = 57.1 nGyh-1, the standard deviation =15.2 nGyh-1, the maximum value =107.2 nGyh-1, and the minimum value=23.1 nGyh-1. On the soil of the basement rock in Okinoshima, the terrestrial γ-ray dose rate of Oki-gneiss is 72±15 nGyh-1, which is about 1.6 times as big as the reported value for metamorphic rock and others are the same in the literatures. It is considered that the terrestrial γ-ray dose rate of Okigneiss has been more strongly affected by the granitic magma which has been interpenetrated in the process of this formation. In Okinoshima, it is suggested that the geological features of the basement rock remain in the surface soil, due to a good correspondence between the geographical distribution of terrestrial γ-ray dose rate and the subsurface geology. And then, in the relation between the terrestrial γ-ray dose rate and the atmospheric 222Rn concentration, the magnitude of 222Rn concentration is smaller than this of place on large land area. Because of a small land area in Okinoshima, this is caused that the land air is mixed with the sea air by the advection for a long time except the time from the sunset to around the midnight. It is suggested that the time and space change characteristic of the diffusion and mixture process is different in contrast to a place of large land area.