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Home  >  Volume 31 (July 2015)

Measurement of Natural Radioactivity levels in the Topsoil of Abandoned Tantalite Mine in Southwestern, Nigeria by Olowookere C. J., Adeoje E.A., Jibiri N.N. and Igboama W.N. (pages 161-166)
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Activity concentration of naturally occurring radionuclides in the topsoil of an abandoned tantalite mine at Awo in Osun State was measured using gamma ray spectrometry method. The results indicate that activity concentration of 238U, 232Th and 40K vary from 36.91 ± 3.44 to 517.21 ± 30.24 Bq kg-1,  92.12 ± 21.06 to 261.61 ± 52.88 Bq kg-1, and 1001.06 ± 6.88 to 1902.25 ± 11.07 Bq kg-1 respectively. The mean activity concentration of radionuclide: 238U, 232Th and 40K are 282.86 ±17.44,164.29 ±34.73 and 1391.99 ±8.78 respectively. The mean radium equivalent activity concentration,   obtained in this study is 618.33 Bq kg-1. This is higher than the recommended reference value of 370 Bq kg-1 for safe use. Moreover, the mean external ( ) and internal ( ) health hazard indicesare greater than unity, indicating that intervention is necessary in the present study location. The result of  the average total external gamma dose rate (288.24 nGy h-1) is higher than Indian average value (90 nGy h-1) and the world average (86 nGy h-1) . The results of this study show that the soil of the study area contains a relatively higher activity concentration above the recommended reference value and could be considered unsafe for building construction.


Keywords: Natural radioactivity, activity concentration, radium equivalent activity, health hazard index,                     tantalite mine.