Estimation of Background Radiation from A Soil Sample from A Barley Farm Area and Malt Factory in East Arsi, Ethiopia

Abstract

The aim of this work is to estimate the background radiation of a soil sample from the barley farm area and Malt factory in East Arsi, Ethiopia. The technique of gamma-ray spectrometry with a high-purity germanium (HPGe) gamma-ray detector and a PC-based MCA was used. The activity concentration levels due to 40K, 137Cs, 238U, and 232Th were measured within the study area at a depth of 30 cm. The soils of the study region are used as construction material by many farmers. The measured specific activity of those radionuclides was compared with the data reported worldwide. The specific activity of radionuclides was estimated in both study locations. The specific activity 238U of soil samples ranged from 41.0 Bq kg-1 to 30.7 Bq kg-1 in the barley farm, with a mean value of 37.7 Bq kg-1, and for malt ranged from 23.8 Bq kg-1 to 40.6 Bq kg-1, with a mean value of 32.5 Bq kg-1. The specific activity of 232Th in soil samples ranged from 89.9 Bq kg-1 to 156.0 Bq kg-1, with a mean value of 118.6 Bq kg-1, whereas for the Malt factory ranged from 121.0 Bq kg-1 to 128.0 Bq kg-1, with a mean value of 123.7 Bq kg-1. In barley soil samples, the specific activity of 40K ranged from 401.0 Bq kg-1 to 530.0 Bq kg-1 with a mean value at the Malt plant ranged from 518 Bq kg-1 to 598.0 Bq kg-1, with a mean value of 553.6 Bq kg-1. Similarly, the specific activity of 137Cs was determined in both the barley farm and the malt Factory. In barley farm soil samples, it ranged from 3.3 ±0.6 Bq kg-1 to 5.34±0.6 Bq kg-1, and with a mean value of 4.3 Bq kg-1 whereas, in the Malt factory it varied from 3.1 ±0.7 Bq kg-1 to 5.3 ±0.7 Bq kg-1, and with a mean value of 4.5 Bq kg-1. The absorbed dose rate within the barley farm ranged from 24.6 ±2.9 nGyh-1 to 34.1 ±2.9 nGy h-1, and with a mean value of 30.6 nGyh-1, whereas, in the Malt factory, it varied from 31.3 ±1.3 nGy h-1 to 35.5 ±1.3 nGyh-1, and with a mean value of 33.5 nGy h-1. The annual effective radiation dose for BSS and MFSS was calculated to be 37.6 mSv y-1and 41.1mSv y-1. This study revealed that this region lies within a medium radiation background when compared with the world's average. The marginal value of dose is higher within the Malt factory area because of fertilizer consumption for cultivation. Since these estimated background and radiological impact factors are below the recommended values, it seems that there is no potential radiological health hazard related to the soils from both BSS and MFSS in Arsi Asella, Oromia, Ethiopia.