Assessment And Investigation Of Natural Radioactivity Levels In Leaves Of Khat And Agricultural Soil Samples Collected From Haramaya East Hararghe Ethiopia Using Gamma Spectrometry

The radiation released from natural radioactive materials (commonly, 40K,238 U, andrn232Th series) performing natural radioactivity, which is out of control, absorbed byrnthe human’s body, arising from a natural source such as cosmic ray, terrestrial, andrnexposure from inhalation or intake radiation sources. Those natural radionuclidesrnare typically present in rock and soil in different amounts and levels of activity, withrnsubsequent distribution to the environment and transfer to humans through inhalationrnand food ingestion (soil-plant-humans) causes health risks.rnThis study aims to assess and investigate radioactivity levels, radiological hazardrnindices in six samples of leaves of Khat plants, and six of its soil (0-30 cm deep)rnsamples collected from Haramaya University area. The measurement had been carriedrnout using a high-efficiency gamma-ray spectrometer with Digital Signal Analyser,rn(DSA) coupled with a High Purify Germanium (HPGe), p-type detector. The gammarayrnspectrometers are controlled by GENIE(2K)-high channel number performance,rncomputer software, and output result are displayed on personal computer. The investigationsrnidentify naturally occurring radionuclide’s from 238U, and 232Th series, andrn40K, in addition to those, 137Cs in agricultural soil and 54Mn in leaves of Khat samples.rnThe activity concentrations of 238U, 232Th, and 40K in Khat farm soils samples rangernfrom 21.43 } 0.98 to 30.77 } 0.62,Bqkg−1, with a mean value of 23.72 } 0.85Bqkg−1,rn69.27 }3.17 to 168.78 }7.55,Bqkg−1, with an average value of 111.50 }4.21Bqkg−1, andrn542.15 }22.73 to 1045.96 }43.4, 4Bqkg−1, with an average value of 794 }26.44Bqkg−1,rnrespectively. The activity concentrations of 40K and 232Th obtained in all samples ofrnthe soils are higher than the recommended reference levels. The radium equivalent activityrnrange from 221.61 }9.83 to 331.57 }13.81,BqKg−1, with an average value 244.31rnBqKg−1, which is relatively higher. Gamma-ray radiation hazards caused by primordialrnradionuclides of 40K, 238U and 232Th, evaluated were, the absorbed dose rate rangernfrom 76.52 }3.40 to 152.57 }6.7, nGyh−1, with a mean value of 113.74 }4.12nGyh−1,rnwhich is higher than the global mean value, annual effective dose range from 0.09 }0.00rnto 0.19 }0.01,mSvy−1, with an average value of 0.14 }0.01mSvy−1, which is above thernworld average. The calculated values of the external and internal index for agriculturalrnsoil samples range from 0.44 to 0.72, with a mean value of 0.63, and 0.51 to 0.96, withrna mean value of 0.72, respectively, which are relatively high but less than the worldrnpermissible value. Also the result of radioactivity level index (Iγ) in soils sample isrnranging from 0.61 } 0.03 to 1.21 } 0.05, with an average values of 0.90 } 0.03 , wherernestimated values of Iγ in some soil samples are higher than one and an average relativernivrnhigher.rnThe average concentrations of 238U, 232Th, and 40K in leaves of Khat samples werern1.32 } 0.24, 10.36 } 0.96, and 273.39 } 7.39,Bqkg−1, respectively. The radium equivalentrnactivity, and internal hazard indices calculated to this plant were varied fromrn25.20 } 2.471 to 39.50 } 2.137, BqKg−1 with average 34.44 } 2.186 BqKg−1 and fromrn0.05 to 0.11, with average 0.09, respectively. The average ingestion effective dose duernto intake this plant samples 238U, 232Th, and 40K calculated for adult is, 0.2 }0.04,rn1.31 }0.12, and 0.81 }0.03, mSv/y,respectively, with the total summation an average,rn2.32 }0.18 mSvy−1. These values are higher than the permissible limits of the world’srntotal average ingestion effective dose. The obtained results were compared with therninternational recommended values.

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