The activity concentrations of natural radionuclides40K, 226Ra and 232Th in soil samples taken from the tin mining area in Gura topp Jos were measured by gamma spectrometry using Sodium Iodide detector. The average specific activity concentrations of 40K, 226Ra and 232Th determined in the soil sample ranged from 543.35±0.64Bq/Kg to 11.26±3.16Bq/Kg with mean activity concentration of 161.96±7.56Bq/Kg for 40K, that of 226Ra ranged from 144.20±10.18Bq/Kg to 7.19±1.23Bq/Kg with the mean activity of 46.47±5.19Bq/Kg while232Th ranged from 1267.91±15.37Bq/Kg to 76.08±3.38Bq/Kg, with mean activity concentration of 396.17±7.69Bq/Kg. The results indicate that the activity concentration of 40K was found to be below the world average while that of 232Th and 226Ra were detected to be above the world average value. This suggested that the level of exposure to radiation in the study area has excess thorium and radium activities which pose significant health hazard and is considered radio-logically unsafe for human to cultivate on the land.
Key words: Activity concentration, Gamma spectrometry, Natural radionuclides and Sodium
Iodide detector.
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