TY - JOUR
T1 - Differences of natural radioactivity and radon emanation fraction among constituent minerals of rock or soil
AU - Sakoda, Akihiro
AU - Nishiyama, Yuichi
AU - Hanamoto, Katsumi
AU - Ishimori, Yuu
AU - Yamamoto, Yuki
AU - Kataoka, Takahiro
AU - Kawabe, Atsushi
AU - Yamaoka, Kiyonori
PY - 2010/6/1
Y1 - 2010/6/1
N2 - We examined differences in the radioactive characteristics among the main minerals forming granite materials. Using a non-toxic high-density agent, minerals were separated from rock (granite-gneiss) and soil (weathered granite) samples. The natural radioactivity (238U and 226Ra) and radon emanation fraction of the minerals were then studied by gamma-ray spectrometry. The radon emanation fractions (27-43%) of the minerals from the soil were much higher than those (0.6-4.6%) of the rock minerals. Additionally, the emanation fractions differed greatly among the minerals separated from both the bulk rock and soil. These results were discussed in terms of the differences of surface area and radium distribution in the mineral grains. It was noticeable that a higher emanation fraction than expected for quartz was commonly observed in the rock and soil samples. We then estimated the contribution of each constituent mineral to the total radon exhalation from the bulk samples. The result depended not only on the radon emanation fraction, but also on the 226Ra activity and the mineral content. Furthermore, using the obtained data, we also discussed the effect of grain size on radon emanation and why this has been reported to vary markedly in previous studies.
AB - We examined differences in the radioactive characteristics among the main minerals forming granite materials. Using a non-toxic high-density agent, minerals were separated from rock (granite-gneiss) and soil (weathered granite) samples. The natural radioactivity (238U and 226Ra) and radon emanation fraction of the minerals were then studied by gamma-ray spectrometry. The radon emanation fractions (27-43%) of the minerals from the soil were much higher than those (0.6-4.6%) of the rock minerals. Additionally, the emanation fractions differed greatly among the minerals separated from both the bulk rock and soil. These results were discussed in terms of the differences of surface area and radium distribution in the mineral grains. It was noticeable that a higher emanation fraction than expected for quartz was commonly observed in the rock and soil samples. We then estimated the contribution of each constituent mineral to the total radon exhalation from the bulk samples. The result depended not only on the radon emanation fraction, but also on the 226Ra activity and the mineral content. Furthermore, using the obtained data, we also discussed the effect of grain size on radon emanation and why this has been reported to vary markedly in previous studies.
KW - Heavy liquid separation
KW - Mineral
KW - Ra
KW - Radon emanation fraction
KW - Rock
KW - Soil
KW - Specific surface area
KW - U
UR - http://www.scopus.com/inward/record.url?scp=77649275094&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=77649275094&partnerID=8YFLogxK
U2 - 10.1016/j.apradiso.2009.12.036
DO - 10.1016/j.apradiso.2009.12.036
M3 - Article
C2 - 20117007
AN - SCOPUS:77649275094
SN - 0969-8043
VL - 68
SP - 1180
EP - 1184
JO - Applied Radiation and Isotopes
JF - Applied Radiation and Isotopes
IS - 6
ER -