Measurements Of Natural Radioactivity Levels In The Soil Coffee And Zuwaye Lake Water Samples Collected From The Selected Area In Ethiopia By Using Gamma Ray Spectroscopy.

People are exposed to radioactivity in soil, plant and even in other environment that is raised fromrnuranium, thorium and potassium-40 radionuclides. Environmental radioactivity and the associatedrnexternal exposure due to gamma radiations depend primarily on the geological, geographical andrnhuman activities. In this study the activity concentration of 238U, 232Th and 40K radionuclides wererndetermined in 12 soil samples, Four coffee samples and Four Zuwaye lake water samplesrncollected from some parts West-Arsi Zone, Shashemane and Zuwaye, Ethiopia using High PurernGermanium Detector (HPGe). The average activity concentration of 238U, 232Th and40K in the soilrnsamples was 45.83, 100.525, 845.65Bq/Kg, respectively. These values were higher than thernaverage world recommended values for 238U , 232Th , 40K , respectively which are 35, 30 and 400rnBq/Kg for 238U , 232Th , 40K respectively [UNSCEAR, 2000].rnDuring our experimental activities our detector could identify only potassium-40 in the coffeernsamples. All coffee samples had 591.185 Bq/Kg average values of 40K concentrations that werernhigher than the acceptable value (412 Bq/kg) [UNSCEAR, 2010].rnActivity concentration of 238U in Lake Zuwaye Water was vary from 2.94±0.25 Bq/L torn3.02±0.27 Bq/L with an average value of 2.99±0.267 Bq/L, 232Th was vary from 6.9±0.73 Bq/L torn8.39±0.82 Bq/L also with an average value of 7.5 ±0.76 Bq/L and the activity concentration ofrn40K varies from 98.12 4.16154 to 101.99 4.91556 with an average value 99.77±4.80Bq/L.rnThe activity concentration from the studied areas were found to be below WHO guidelines of 10rnBq/L for 238U and higher than 1 Bq/L for 232Th. The World Health Organization recommendedrnlevel of 40K in water meant for drinking is unavailable.rnThe values of radium equivalent for different soil samples in area under investigated were rangedrnfrom 124.96 to 330.7 Bq/kg with average value 248.75Bq/kg which is lower than thernrecommended maximum value 370 Bq/kg [Gilmore, G.R.,2008].rnThe calculated values of Dr were found to vary from 96.64 to 191.02nGy h-1, with an averagernvalue of 149.5117nGy h-1. The measured average absorbed dose rate in the air and the measuredrnvii |rnaverage value of the representative level index are higher than the recommended internationalrnlevels of 55 nGy h-1. Such locations are not safe for human residency and agriculture.rnThe calculated values for Dout, Din, and Dtot respectively 0.185, 1.035, and 1.22 mSv/year tornglobal measured values, these values were all higher than the assigned worldwide values of 0.08,rn0.42, and 0.5 year-1, respectively [UNSCEAR,2000]. The locations from which the soil samplesrncollected were all not safe according to the Radiation Protection, and such locations cannot bernclassified as hazard free.rnThe external hazard index (Hex) and internal hazard index (Hin) due to the emitted -rays ofrnthe soil samples were calculated according to the following criterion: The value of Hex must bernlower than unity in order to keep the radiation hazard insignificant. The calculated externalrnhazard index values were found to vary between 0.43 and 0.78 with average value of 0.668 thesernvalues are less than unity, which is 33.2 % less than world recommended value. The calculatedrninternal hazard index values were found to vary between 0.5 and 0.93 with average value of 0.79,rnwhich is 11.0% less than world recommended value [Dabayneh K et al,.2008].rnRadioactivity level index vary from 1.19 to 2.395 Bq/Kg with average values is 1.917 Bq/Kg.rnThe average value of Radioactivity level index is higher than the recommended safe limit ≤ 1rn[Thabayneh K, Jazzar M.2012]. Therefore, the soils have radiation hazard and are harmful tornsociety living there.rnThe values of radium equivalent for different coffee samples in study area were vary from 42.5rnto 54.92 Bq/Kg with average value 47.44Bq/Kg which is lower than the world recommendedrnmaximum value 370 Bq/Kg [Gilmore, 2008].rnThe determined values of absorbed dose rate (Dr) were found to vary from 23.73 to 30.67nGy h-rn1, with an average value of 26.49nGy h-1. The measured average absorbed dose rate in the air wasrnlower than the recommended international levels of 55 nGy h-1[Turner J et al., 2007] and therncoffee was safe for use.rnThe determined average values for Dout, Din, and Dtot respectively 0.0325, 0.181, and 0.107rnmSv /year to global measured values, these values were all lower than the worldwide values ofrn0.08, 0.42, and 0.50 mSvyear-1, respectively [UNSCEAR, 2000].rnviii |rnThe external (Hex) and internal (Hin) hazard index due to the emitted -rays of the coffeernsamples were calculated and examined according to the following criterion: The value of Hexrnmust be lower than unity in order to keep the radiation hazard insignificant. This is the radiationrnexposure due to the radioactivity from a construction material, limited to 1.5 mGy•y−1. Thernmaximum values of Hex equal to unity correspond to the upper limit of Raeq (370 Bq/Kg) [48].rnThe calculated external hazard index values were found to vary between 0.115 and 0.148 withrnaverage value of 0.128 these values are less than unity, which is 87.2 % less than worldrnrecommended value. The calculated internal hazard index values were found to vary betweenrn0.115 and 0.148 with average value of 0.128, which is 87.2% less than world recommendedrnvalue [Knoll G.F, 2000].rnRadioactivity level index to vary between 0.36 to 0.475 Bq/Kg with average value is 0.4 Bq/Kg.rnThe average value of Radioactivity level index is lower than one the recommended safe limit ≤ 1rn[Van Rooyen T.J., 2002]. Therefore, the coffee had no health radiation hazard.rnHence it can be concluded that the radionuclide concentration of measured coffee samples posesrnno radiological health hazard to the community.rnThe annual effective dose calculated for the Zuwaye lake Water was varied from 0.081 to 0.09rnmSv/y with an average of 0.086 mSv/y. This value, when compared with the ICPR standardrnvalue of 1mSvyr-1 is very low, hence, it can be concluded that the radionuclide concentration ofrnZuwaye Lake water is negligible and poses no radiological health hazard to the community.

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