Radiation hazard in soil from Ajaokuta North-central Nigeria (original) (raw)
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Radioactivity of surface soils from Oyo state, South Western Nigeria
The ac vity concentra ons of some radionuclides in soil samples collected from 20 loca ons in 8 major towns in Oyo State, Southwestern Nigeria have been determined by gamma-ray spectrometry technique. Materials and Methods: The ac vity concentra ons were determined using high-purity germanium (HPGe) detector (Canberra Industries Inc.). The outdoor absorbed dose rates in air at about 1.0 m height were es mated from the ac vity concentra ons and dose rate conversion factors for the radionuclides. The annual outdoor effec ve dose equivalent rates were also es mated for urban and rural areas of the state using the calculated absorbed dose rates in air. Results: Determined specific ac vity concentra ons of the radionuclides ranged from 1±0.4 Bq kg -1 for 137 Cs to 1190±30 Bq kg -1 for 40 K. The es mated outdoor absorbed dose rates in air varied from 52 nGy h -1 in Egbeda (a rural area) to 414 nGy h -1 in Eruwa (also a rural area). The mean annual outdoor effec ve dose equivalent for the urban areas in the state was 0.1 mSv y -1 while that of rural areas was 0.3 mSv y -1 with a standard devia on of 0.02 mSv y -1 and 0.3 mSv y -1 respec vely. The mean for the study area was 0.2 mSv y -1 . Conclusion: The mean annual outdoor effec ve dose values for the urban and rural areas, for the whole study area are higher than the world average annual outdoor terrestrial radia on value of 0.07 mSv y -1 reported by the United Na ons Scien fic Commi ee on Effects of Atomic Radia on (UNSCEAR) for individual members of the public.
Assessment of radiological parameters of soil in Kogi State, Nigeria
Environmental Forensics, 2017
The natural radioactivity levels of soil samples collected from four local government areas in Kogi State, Nigeria were measured using a hyper-pure germanium detector, and the radiological hazard parameters associated with them were estimated. The measured concentration ranged from 7.82 § 0.63 to 82.22 § 1.99 Bq kg ¡1 for 238 U, 11.05 § 1.10 to 114.86 § 4.72 Bq kg ¡1 for 232 Th, and 3.38 § 0.50 to 1272.20 § 23.36 Bq kg ¡1 for 40 K. Omala local government was found to have the highest concentrations of 238 U (44.31 Bq kg ¡1) and 232 Th (52.13 Bq kg ¡1), while Ajaokuta has the highest concentration of 40 K (711.72 Bq kg ¡1). The lowest activity concentrations of 238 U and 232 Th were measured from soil samples collected from Ankpa local government area and 40 K from Dekina local government area. It was noted that the activity concentrations of 40 K were generally low for all the areas investigated except for Ajaokuta areas. The radium equivalents calculated for all the locations were observed to be lower than the radiation protection regulatory body reference value of 370 Bq kg ¡1. The radiological parameters estimated for most of the locations compared well with world average values, except for Odogba-okaba, Salem University, Forest, Nepa, Gerugu, Niger Bridge, Igaliwu, Ijeke-ogane, Bagana, and Abegikolo villages, whose values exceeded the recommended limit. This may suggest that those living or working in these areas may be exposed to higher radiation burden from the natural radionuclides.
Journal of African Earth Sciences, 2016
Ground investigations of the activity concentrations from primordial radionuclides (238 U, 232 Th and 40 K) were conducted in Akpabuyo, southeastern Nigeria. These investigations were aimed at assessing the magnitude and spatial distribution of activity concentrations from primordial radionuclides. Also, radiological hazard assessment and their associated risk to both human environmental healths and suitability of soils in the area for constructing dwellings places will be made. Instrument used for the investigations, which were conducted both randomly and along 6 profiles with inter-profile distance of 100 m, was a potable GRS-2 model of a Pico Envirotec spectrometer. Activity concentrations in the area, which vary with spatial distribution of soil texture, lithology, land use and topography, range between 2.22 and 116.09 Bq kg À1 (mean of 34.67 Bq kg À1) for 238 U, 3.65e87.41 Bq kg À1 (mean of 38.59 Bq kg À1) for 232 Th and 6.26e384.99 Bq kg À1 (mean of 114.66 Bq kg À1) for 40 K. The mean activity concentrations of 238 U and 232 Th are marginally higher than world averages of 30 and 39 Bq kg À1 respectively. However, the activity concentration of 40 K, which is the most abundant radionuclide (60.02%), is less than the world average of 400 Bq kg À1. Results obtained from skew and kurtosis analyses of the activity concentration data show that the distribution of 238 U and 232 Th radionuclides in the soils is nearly symmetrical. The radiological hazard indicators computed from the activity concentrations of the radionuclides are all below maximum permissible limits. For instance, values of radium equivalent, which vary from 41.72 to 171.02 Bq kg À1 (average of 98.68 Bq kg À1), are below the permissible limit of 370 Bq kg À1. External and internal hazard indices vary between 0.11 and 0.46 Bq kg À1 (mean of 0.27 Bq kg À1) and 0.14e0.72 Bq kg À1 (mean of 0.36 Bq kg À1) respectively. These results are below the 1 Bq kg À1 benchmark required for materials to be safe for use in constructing residential buildings. Absorbed dose, indoor and outdoor annual effective dose rates vary from 19.37 to 76.72 nGy h À1 (mean of 44.11 nGy h À1), 0.10e0.38 mSv yr À1 (mean of 0.22 mSv yr À1) and 0.02e0.09 (mean of 0.05 mSv yr À1) respectively. The mean absorbed dose rate is almost equal to the world average of 44 nGy hr À1 , but the means of the indoor and outdoor annual effective doses are below the 0.50 mSv yr À1 limit set for materials to be safe. Thus, the soils in Akpabuyo are safe for use in constructing dwelling places for the population. However, periodical monitoring of the radionuclides and radioisotopes should be performed.
Natural radiation levels and health hazard indices of soil in Owerri Nigeria
The natural radiation of soil samples from three local governments areas that make up Owerri city in Imo state, Nigeria were measured using gamma ray spectrometer. The mean values obtained were 167.2 ± 10.5 ( ), 19.7 ± 1.9 ( ) and 18.1 ± 3.3 ( ) for 40 K , 226 Ra and 232 Th respectively. These values were used to evaluate the radiological health hazard indices using standard analytical methods. The results showed that the mean value of radium equivalent activity is 58.5 , while the values of absorbed dose rate ( ) and annual effective dose equivalent ( ) are 27.1 and 132.78 respectively. The values of external and internal health hazard indices are 0.16 and 0.21 respectively. All these values obtained are lower than their world permissible United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR) values for such environment. This shows that the risk due to radiation contamination in the city of Owerri is low.
2017
Radionuclides are ubiquitous in nature and they emit energy in form of radiations to attain stability. The earth’s crust contains various radioactive isotopes such as uranium, thorium, radon, tritium, carbon, and potassium among others. These isotopes and their progenies have different half lives, which emit various types of radiations such as alpha, beta and gamma rays. Additionally, cosmic radiation from the sun contributes to gamma rays surrounding the human body. In other words, the controlled manmade-artificial background radiation results from several sources such as fallouts of weapons testing, radioactive waste, and the use of radioisotopes in radiation-therapy. (McGraw-Hill, 1980). Natural Radiation contributes to 80% of the total dosage the body may receive, while artificial radiation accounts for the other 20% dosage of human exposure (IAEA, 1986). Exposure to this radiation can cause damage to living cells resulting to either death as a result of exposure to large dose o...
International Journal of Low Radiation, 2009
Abeokuta and Jos Plateau, towns in the southwestern and northern parts of Nigeria, respectively, are situated in areas of high background radiation. The use of farm soil for the construction of dwellings by local residents and for agricultural purposes in these areas may present scenarios for both enhanced external and internal exposure pathways to the population. In order to assess the gamma radiation exposure levels, soil samples from 65 farms in Jos Plateau and 47 farms in Abeokuta were collected. Using gamma-ray spectroscopy the activity concentrations of 226 Ra, 232 Th and 40 K in the samples were determined. From the activity concentrations of these radionuclides, the absorbed gamma dose rates were calculated. The obtained mean total absorbed gamma dose rates varied between 194 ± 59 nGy h-1 and 350 ± 270 nGy h-1 in Jos Plateau, whereas in Abeokuta, it was 167 ± 140 nGy h-1. These results, along with the results of the estimated annual effective dose rates, radium equivalent (Ra eq), external hazard index (H ex), internal hazard index (H in) and gamma index (I γ), are presented in this paper. The results of this study indicate that the populations in the investigated areas are likely subjects for high radon burden in their dwellings.
Environmental Forensics, 2013
Gamma ray spectrometric technique has been used to determine activity concentrations of some primordial radionuclides in the naturally occurring uranium, actinium and thorium series and of non-series 40 K in soil samples collected from five major towns in Oyo State, Southwestern Nigeria. Activity concentration determination was done using a high purity germanium (HPGe) detector. It ranged from 85.83 ± 4.04 Bq kg −1 to 1,850.60 ± 36.83 Bq kg −1 for 40 K; 5.23 ± 0.34 Bq kg −1 to 198.31 ± 4.10 Bq kg −1 for 208 Tl (indicator for 232 Th) and 7.82 ± 0.42 Bq kg −1 to 64.65 ± 2.00 Bq kg −1 for 214 Bi (indicator for 238 U). The outdoor absorbed dose rate in air due to each of the primordial radionuclides was calculated from the mean values of the activity concentration in each sample. Values ranged from 3.60 ± 0.17 nGy h −1 to 77.73 ± 1.55 nGy h −1 for 40 K, 3.48 ± 0.23 nGy h −1 to 132.07 ± 2.73 nGy h −1 for 208 Tl and 3.35 ± 0.21 nGy h −1 to 27.73 ± 0.86 nGy h −1 for 214 Bi. The absorbed dose rate in air was the highest for rocky areas, while the lowest value came from non-rocky, non-industrialized areas. The estimated annual outdoor effective dose equivalents for the two rocky areas were 385.76 μSv y −1 and 221.28 μSv y −1 . The estimated annual outdoor effective dose equivalents for the two industrialized areas were 64.05 μSv y −1 and 47.65 μSv y −1 . The value for non-rocky, non-industrialized areas was 19.19 μSv y −1 . The average value for the study area was 147.59 μSv y −1 . The estimated collective effective dose equivalent for the area was 9.77 × 10 2 man-Sv y −1 . The expected number of people in the study area at risk of incurring cancer per year as a result of radioactivity in the soil was estimated to be 11; this value represents approximately 7% of the estimated 160 people for 18 Nigerian cities, approximately 69% of 16 people estimated for oil producing areas of Nigeria and less than the United States Environmental Protection Agency regulatory limit of 1 cancer case to 10,000 people. Also, this result shows that local variability of natural radionuclides in soil depends on local geology of the area. The incidence number was 2.4 people per million.
J. Appl. Sci. Environ. Manage., 2019
The aim of this study is to assess the activity concentration of radionuclides and the possible health risk associated with exposure to radiation from the soil samples collected from two higher institutions in Esan land of Edo State, Nigeria. The gamma spectrometry system was used to determine the activity concentrations of radionuclides 238 U, 232 Th and 40 K in the surface soil samples. The activity concentration of radionuclides ranged from 7.16 ± 0.63 to 102.37 ± 2.37 BqKg for 40 K, from 0.75 ± 0.05 to 3.13 ± 0.11 BqKg for 238 U and from 2.25 ± 0.20 to 9.02 ± 0.40 BqKg for 232 Th. The measured mean activity concentration of radionuclides for 40 K, 238 U and 232 Th from the examined topsoil of Samuel Adegboyega University were 57.80 ± 1.7 BqKg ; 2.07 ± 0.09 BqKg and 6.89 ± 0.34 BqKg respectively. At the neighbouring higher institution; College of Education, Igueben, the mean activity concentration of 40 K, 238 U and 232 Th in its surface soil were 30.19 ± 1.22 BqKg , 1.41 ± 0.07 BqKg and 4.85 ± 0.28 BqKg respectively. The total mean values for radiation dose estimation for Radium Equivalent Activity, Absorbed Dose, Excess Lifetime Cancer Risk, Outdoor and Indoor Annual Effective Dose Equivalent are 13.20 BqKg , 6.03 /ℎ, 0.026, 7.40 /, and 29.60 / respectively. These values were found to be lower than the global average values. Hence, there is no radiation induced health threat to the students and members of staff in the study area.
Baseline Radionuclide Distribution Patterns in Soil and Radiation Hazard Indices for Abak, Nigeria
Advances in Physics Theories and Applications, 2014
A gamma spectroscopy analysis for the naturally occurring radionuclides 226 Ra, 232 Th and 40 K has been carried out for soil samples collected from communities in Abak Local Government Area of Akwa Ibom State to determine the concentration and distribution patterns of these radionuclides in the study area and to assess the possible radiological risks from the soil. The activity concentration of the samples range from 14.80±1.16Bq/kg to 150.20±11.47Bq/kg with a mean value of 98.709±7.693Bq/kg for 40 K; from 14.52±3.49Bq/kg to 42.04±8.59Bq/kg for 238 U with a mean of 24.826±5.425Bq/kg and from 3.05±0.27Bq/kg to 7.00±0.58Bq/kg with a mean of 5.172±0.31Bq/kg for 232 Th. These values are within international regulatory standards. Assessment of the radiation hazard levels for the area gave values of 18.789±3.102nGy/h for absorbed dose, 0.3±0.05Bq/kg for representative level index, 39.82±6.65Bq/kg for radium equivalent, 0.11±0.02 for external hazard index, 0.18±0.032 for internal hazard index and 0.023±0.004mS/yr for effective dose rate. These indices are much lower than the ICRP permissible limits for soil showing that the soil of the study area poses no radiological threats to the public.