In situ measurements of thoron exhalation rate in Okinawa, Japan.
Thoron exhalation rates from the ground surface were measured at 57 sites on Okinawa Island, Japan, using a ZnS(Ag) scintillation detector equipped with photomultiplier. The arithmetic means ± SD, median ± SD, minimum and maximum of the rates (unit: Bq m(-2) s(-1)) were estimated to be 1.9 ± 1.4, 1.6 ± 0.3, 0.04 and 6.2, respectively. The soils distributed on the island are generally classified into dark red soils, residual regosols, as well as red and yellow soils. While it was assumed that the soils were originated from the bedrock, recent studies suggested that the main material of dark red soils is the East Asian eolian dust. In the dark red soils area, the exhalation rate is relatively higher than that in the other areas. This suggested that the eolian dust was an enhancer for the environmental thoron concentration on Okinawa Island.
Shiroma
Y
Y
Department of Physics and Earth Sciences, Faculty of Science, University of the Ryukyus 1 Senbaru, Nakagami-gun, Okinawa, Japan.
Isa
N
N
Hosoda
M
M
Sorimachi
A
A
Ishikawa
T
T
Tokonami
S
S
Furukawa
M
M
D000392:Air Movements; D000396:Air Pollutants, Radioactive; D016902:Air Pollution, Indoor / Q000032:analysis*; D004781:Environmental Exposure; D005740:Gases; D005843:Geography; D006813:Humidity; D007564:Japan; D011834:Radiation Monitoring / Q000295:instrumentation*; D011874:Radiometry; D011886:Radon / Q000032:analysis*; D017687:Radon Daughters / Q000032:analysis*; D012306:Risk; D012987:Soil
D000396:Air Pollutants, Radioactive; D005740:Gases; D017687:Radon Daughters; D012987:Soil; D011886:Radon