Natural radioactivity in coastaline area soil of Ado-Odo/Ota has been carried out to ascertain the presence of radionuclides using gamma-ray spectroscopy (HPGe detector). The result showed that U-238, Th-232 and K-40 ranged from 24 ± 7-49 ± 10; 67 ± 6-120 ± 9 and 88 ± 17-139 ± 20 Bqkg-1 respectively. The radium equivalent for the samples ranged from 132.51 to 230.91 Bqkg-1 with mean value of 185.89 Bqkg-1. The mean value for the gamma dose rate for the soil samples was estimated to be 81.32 nGyh-1. The estimated values of annual effective dose equivalent ranged from 0.61 to 1.07 mSv y-1. The estimation of alpha index representative (Iα) ranged from 0.12 to 0.24 with mean value of 0.21 while the gamma representative index ranged between 0.465 and 0.810. The activity utilization index of the soil samples ranged from 1.09 to 1.89 with mean value of 1.53. The radiological implication in the study area has shown that the soil samples with gamma dose rate value of 89.99 nGyh-1, 94.39 nGyh-1, 97.40 nGyh-1 and 101.04 nGyh-1 respectively are higher than the recommended value of 80 nGyh-1 and may pose health implication for long term exposure.
The activity levels of 238U, 232Th and 40K in soil surrounding major office complexes in Covenant University were analyzed for radiological hazards to determine the safety of the residents in such environment. Sixteen (16) soil samples were collected, prepared and sent to Acme laboratory in Canada for analysis with the use of high purity germanium detector. The mean activity concentrations of 238U, 232Th and 40K were found to be 45 ± 10, 135 ± 8 and 195 ± 20 respectively. The concentrations of 238U and 232Th were found to be higher than the world recommended standard of 35 and 30, while the result for 40K was noted to be lower than the world safe limit. The average values of Raeq, D, AED, Iyr, Hex and ELCR in this study were estimated to be 252.33 Bq/kg, 110.15 nGy/h, 0.13 mSv/y, 1.78, 0.68 and 0.47 × 10-3 respectively. It was noticed that none of the measured parameters was higher than the internationally recommended safe limits. 232Th was found to be the major contributor to the environmental radionuclides in the area of study. Therefore, the inhabitants of the office complexes whose environment was assessed are considered not be exposed to any radiological hazards.
The risk of natural terrestrial radioactivity on human health is often underestimated, and environmental safety awareness is necessary. Hence, this study aims to assess natural sources of gamma radiation emitter in coastal urban-environment using the radiometric technique. The dosage of gamma radiation from a parent radionuclide such as Uranium-238 (238U), Thorium-232 (232Th) and Potassium-40 (40K) and were measured using portable gamma spectroscopy. The result showed that the measured value of 238U activity was between 10.81 [Formula: see text] 0.69 and 46.31 [Formula: see text] 1.43 Bqkg-1. The mean value was estimated to be 35.44 [Formula: see text] 0.97 Bqkg-1 which is slightly higher than the world average. Meanwhile, 232Th activity ranges from 28.42 [Formula: see text] 1.12 to 69.43 [Formula: see text] 1.76 Bqkg-1 with the calculated mean value of 92.57 [Formula: see text] 1.17 Bqkg-1 while 40K activity ranged between 31.30 ± 1.32 and 328.65 ± 2.32 Bqkg-1 with the estimated mean 137.59 [Formula: see text] 2.42 Bqkg-1. Radiological parameters such as radium equivalent (Req), internal hazard (Hint) and external hazard (Hext) assessment were in the range of 66.00 Bqkg-1 to 141.76 Bqkg-1, 0.232 to 0.452 and 0.178 to 0.383, respectively. The measured values of gamma dose-rates ranged between 54.283 ± 0.78 and 117.531 ± 1.14 nGyh-1 with the calculated mean value of 84.770 ± 0.97 nGyh-1.
In this study, we evaluated the activity concentration of natural radionuclides (226Ra, 232Th and 40K) for fifteen (15) different brands of tile samples used for building purposes in Nigeria. The tile samples were analyzed using High purity Germanium gamma detector. The mean activity concentrations of 226Ra, 232Th, and 40K were observed to be 61.1 ± 5.5 Bq/kg, 70.2 ± 6.08 Bq/kg and 514.7 ± 59.8 Bq/kg respectively. Various hazard indices such as absorbed dose rate, external and internal hazard index, annual effective dose rate, Gamma activity Index (Iγ) and Alpha Index (Iα) were calculated. The obtained results showed that the mean radium equivalent activity (Raeq), the absorbed dose rate (D), external and internal hazard index, the annual effective dose (AEDR) equivalent, Gamma activity Index (Iγ) and Alpha Index (Iα) were: 204.42 Bq/kg, 177.61 nGyh-1, 0.55, 0.77, 0.96 mSvyr-1, 0.74 and 0.32 respectively. The average value of radium equivalent obtained in this study is less than that of the recommended value of 370 Bq/kg but the average values of the other radiological hazards for some samples are found to be slightly above international recommended values except Hex, Hin and AEDE which are within the international reference value of unity. The measured concentrations of these radioactive materials were correlated with other previous result obtained from similar tile materials used in other countries and found to be in good agreement with the international standard, however, the tiles are recommended for decoration purposes in Nigeria.