Senbetu, Nigusu2021-11-152023-11-092021-11-152023-11-092021-10-27http://10.90.10.223:4000/handle/123456789/28662In this study, our objective was to measure the level of activity concentration and radiological hazards of soil samples from agricultural and virgin lands of Bale zone, Oromia, Ethiopia. The activity concentrations of naturally occurring radionuclides 238U, 232Th, and 40K were calculated total for of twelve(12) which is six(6) from agricultural and the other six(6) from virgin soil samples randomly collected from four kebele's of Bale zone southeastern part of Ethiopia by mixing equal masses of soil from three di_erent depths starting from 0 to 10cm,then 0 to 20cm, and 0 to 30cm. Gamma-ray spectrometer was applied using high-purity germanium (HPGe) gamma-ray detector and a PC-based MCA that uses Genie 2000 Spectroscopy Software. Additionally, in our some soil samples of two sites there is an arti_cial radionuclide of 137Cs that fallout from any nuclear accidents can be seen when the samples analyzed by Gamma-ray spectrometry using high-purity germanium. The mean value of radioactivity concentrations of 238U , 232Th, and 40K were found to be 21:74_0:569 with ranged from 6:565_0:206 to 41:15_0:748, 71:72_1:95 with ranged from 26:2_0:77 to 122_2:57 and 1111:5_3:39 Bq kg􀀀1 with ranged from 555_8:94 to 2180 _ 3:21 Bq kg􀀀1 , respectively, in agricultural soils and 18:89 _ 0:667 with ranged from 7:54_0:378 to 30:25_1:340, 69:93_2:38 with ranged from 36:2_0:96 to 121:0_2:55, and 642:83_4:39 Bq kg􀀀1 with ranged from 413_7:01 to 808_1:21 Bq kg􀀀1 , respectively, in virgin soils. The radioactivity concentrations in agricultural soils are higher than those in virgin soils as of phosphate fertilizers added to agricultural land soils. Out of twelve samples the activity concentrations of the arti _cial radionuclide 137Cs was measured by HPGe only in six samples. The mean value was 1:542 _ 0:635 Bq kg􀀀1 with ranged of 0:451 _ 0:507 to 2:19 _ 0:151 Bq kg􀀀1. The minimum activity concentration value of 137Cs was obtained for a soil sample collected from virgin land, similarly the maximum value was measured in a soil sample collected from virgin land site, which is no health e_ects on the people living around the sites where soil samples were collected. The Gamma-ray radiation of radiological hazards caused by speci_c radionuclides of 238U, 232Th, and 40K was evaluated using di_erent hazard indices. The mean values of radium equivalent activity (Raeq), absorbed dose rates (DR), annual e_ective dose(ADR), external hazard index(Hex), and internal hazard index(Hin) are 209:88 _ 3:617 Bqkg􀀀1 which ranged from 93:45 _ 2:110 to 296:46 _ 4:543 Bq kg􀀀1, 101:76 _ 1:873 nGy h􀀀1 which ranged from 45:85 _ 1:001 to 138:73 _ 1:988 iii nGy h􀀀1, 0:12 _ 0:002 mSvy􀀀1 with ranged from 0:06 _ 0:001 to 0:17 _ 0:002mSv y􀀀1, 0.57, ranged from 0.25 to 0.80, and 0.625, ranged from 0.29 to 0.91, respectively, were found in agricultural soils and 168:40_4:402 Bqkg􀀀1 with ranged from 98:92 _ 2:283 to 256:05 _ 4:147 Bqkg􀀀1, 79:28 _ 1:954 nGy h􀀀1 with ranged from 46:87 _ 1:058 to 119:01 _ 1:815 nGy h􀀀1, 0:098 _ 0:002 mSv y􀀀1 with ranged from 0:06 _ 0:001 to 0:15 _ 0:002 mSv y􀀀1, 0.46 with ranged from 0.27 to 0.69, and 0.51 with ranged from 0.31 to 0.75, respectively, were found in virgin soils samples. Further, the annual dose rate was calculated only for outdoor. In a comparison of the world wide average value calculated by UNSCEAR and ICRP with our results mean value for absorbed dose rates (DR),and annual e_ective dose(ADR) were out of the recommended mean values of 59nGy/h and 0.07mSv/y by these institutions. But, others like radium equivalent activity (Raeq), external hazard index(Hex), and internal hazard index(Hin) mean values were within the recommended value. Finally, in all radiological hazard indices when we compare two sites( agricultural and virgin lands), the mean values of agricultural soil were greater than the mean values of virgin soil samples.enNatural RadionuclidesActivity Concentration LevelRadiological Hazard and HPGe Gamma-Ray SpectrometryThesis