J. C. Osimobi

Bio: J. C. Osimobi is an academic researcher from University of Port Harcourt. The author has an hindex of 4, co-authored 4 publications receiving 21 citations.

Radiometric and Radiogenic Heat Evaluation of Natural Radioactivity in Soil Around Solid Minerals Mining Environment in South-Eastern Nigeria

Abstract: Radionuclides activity concentrations in soil around ten solid mineral mining sites have been investigated using sodium iodide [Na(TI)] gamma spectroscopy. Four soil samples and a control sample were collected from each of the selected sites for analyses. The obtained results showed mean concentration values of 33.2 Bq kg−1 for 226Ra, 100.7 Bq kg−1 for 40K and 77.7 Bq kg−1 for 232Th. The estimated radiological risk parameter results have shown average values of 67.5 ηGy h−1 for the Absorbed Dose Rate (DR), 82.8 μSv y−1 for the Annual Effective Dose Equivalent (AEDE), 151.4 Bq kg−1 for the Radium Equivalent (Raeq) and 457.1 mSv y−1 for the Annual Gonadal Equivalent Dose (AGED) which is highly comparable to the allowable WHO value of 300 mSv y−1 and the control value of 177.7 mSv y−1. The average Excess Life Cancer Risk (ELCR) value obtained was 289.6 × 10−6 and the control value 112.9 × 10−6. The average External Hazard Index (Hex), Internal Hazard Index (Hin), Representative Gamma index ( Iγ), and Activity Utilization Index (AUI) obtained were 0.4, 0.5, 1.1 and 1.3, respectively. The Radiogenic Heat produced Q ranged from 248.4 pW kg−1 in Awkuke (ironstone mine) to 608.5 pW kg−1 in Ama-Echi (Silica mine) with an average heat value of 415.8 pW kg−1. The obtained result for lithology [clay] identification showed a mixed clay lithology type. The overall results were found to be higher when compared to previously reported values from similar mineral mining areas, which indicates radiological contamination.

GIS Mapping and Background Ionizing Radiation (BIR) Assessment of Solid Mineral Mining Sites in Enugu State, Nigeria

Abstract: A study of the external background ionizing radiation (BIR) levels in eight solid mineral mining sites in Enugu State has been carried out using two Digilert radiation monitors Radalart-50 and Radalart-100. Thirty two readings of four samplings in each point were taken at different solid mineral sites of the state following standard procedure. The measured BIR levels obtained ranged from 0.012 mR/hr in Nkpologwu silica mining site to 0.028 mR/hr in clay mining site in Enugu-Ekulu with an average of 0.018 ± 0.004 mR/hr, while the corresponding calculated equivalent dose rate ranged from 1.0 mSv/yr to 2.35 mSv/yr with a mean value of 1.51 ± 0.04 mSv/yr. The result obtained indicates that the average exposure level of the studied area is 38.5% higher than the international standard. This suggests the possibility of the presence of radionuclide in the solid minerals mined in Enugu state. However, the values obtained may not cause immediate health challenge to miners and those engaging in commercial activities around these mining sites in Enugu, but may result in long-term health side-effects to residence and miners who put in over twenty-five years in the job. From the forgoing, it is recommended that control mechanism should be adopted for the members of the public, residence, commercial traders as well as miners working in these sites, and to protect the environment.

Excess Lifetime Cancer Risk from Measured Background Ionizing Radiation Levels in Active Coal Mines Sites and Environs

Abstract: A study of the terrestrial Background Ionizing Radiation (BIR) levels of Bunker and Okpara mining site environment in Enugu state has been carried out to estimate the excess lifetime cancer risk. A radiation monitoring meter (digilert 100) and a geographical positioning system (GPS) for GIS mapping were used. The monitoring of the BIR levels was carried out in one calendar year after delineating the environment of the two mining sites into four monitoring locations each. Average BIR levels measured ranged from 0.009 mRh−1 (0.76 mSvy−1) in Enugu new market (Bunker) mine site to 0.039 mRh−1 (2.52 mSvy−1) in Okpara mine site with overall mean value of 0.017 ± 0.007 mRh−1 (1.39 ± 0.60 mSvy−1). The computed average outdoor absorbed dose rate for the study area ranged from 113.10 ± 34.80 ηGyh−1 in Bunker mining area to 217.50 ± 78.30 ηGyh−1 in Okpara mining area, with a mean value of 143.55 ± 52.20 ηGyh−1. The mean annual effective dose equivalent (AEDE) calculated for the study coal mining sites was 0.18 ± 0.07 mSvy−1, while the mean excess lifetime cancer risk (ELCR) was (0.61 ± 0.14) ×10−3 mSvy−1. The dose received by organs was highest in the testes (0.12 mSvy−1), while the liver had the lowest dose values of 0.06 mSvy−1. The study revealed that of the 8 sampling locations and 3840 exposure measurements made, 74.1 % exceeded the world ambient standard levels of 0.013 mRh−1 (1.0 mSvy−1) recommended by UNSCEAR, and the recorded values were higher compared to values reviewed in literature. But the reported results may not constitute any immediate health risk to the residents and coal miners in the study area. The calculated Excess Lifetime Cancer Risk values indicates that the chance of developing cancer by residents and workers in the mine sites of the study area is low and the effective dose for adult organs investigated is insignificant to cause any health related sicknesses or damage to the investigated organs from the present exposure rate.

Natural occurring radionuclide variation with a soil depth profile of Udi and Ezeagu local government areas of Enugu State, Nigeria

Abstract: The assessment of the natural radionuclide concentration with a depth profile of two drilled boreholes in Enugu State, Nigeria was carried out using a gamma spectroscopy detector. Soil samples were collected at 20m depth intervals down the boreholes (wells) with a depth of about 200m and 140m for Well 1 (Amagu-Umuene) and well 2 (Ogulogu-Olo) respectively. The average values of 40K, 226Ra and 232Th obtained is 57.17Bqkg-1, 13.71Bqkg-1 and 10.49Bqkg-1 respectively for Well 1 and 59.77Bqkg-1, 11.49Bqkg-1 and e.eSBqkg-1 respectively for Well 2.The computed absorbed dose and equivalent dose rate has a mean value of 15.20ηGyhr-1 and 0A3mSvyr-1 for Well 1 and 13.3OηGyhr-1 and 0.12mSvyr-1 for Well 2, respectively. These values obtained are well within the world average value and may not result in any significant health effects on human and environmental hazard. The variation of the radionuclides for both wells is irregular down the depth of the boreholes profile. The irregular distribution pattern down the aquifer is attributed to the mineralogy and the geology of the study area.

Measurement of Background Ionizing Radiation Exposure Levels in Selected Farms in Communities of Ishielu LGA, Ebonyi State, Nigeria

Abstract: The perceived implication of increase background radiation levels of farm lands due to inputs of fertilizers and agrochemicals has suggested the need to investigate the background ionization radiation (BIR) levels and associated radiation health parameters in farmlands located in communities of Ishielu LGA of Ebonyi State, Nigeria. An in-situ method of BIR measurement in five farmlands each located in Nkalagu, Ezillo, Okpoto and Nteze communities was carried out using portable GQ GMC-320 Plus radiation meter at an elevation of 1.0 m above ground level with a GPS for geographical location. The BIR levels observed in Nkalagu and Ezillo farmlands are high ranging with same mean values of 0.016±0.002mR/h which is higher than 0.013 mR/h ICRP recommendations for normal environment. The BIR measured at Okpoto and Nteze farmlands are low ranging with mean values of 0.013±0.001 mR/h which is in tandem with ICRP recommendation. The corresponding absorbed doses in all the farmlands and associated excess lifetime cancer risks are far higher than their recommended safe limit of 84.0 ηGy/h and 0.29×10 -3 respectively. The values for the annual effective dose for all the farm lands are lower than the permissible limits of 1.00 mSv/yr for the general public. The study shows that the radiation levels and the doses observed in the farmlands do not constitute any immediate negative radiological health effect on the farmers and general public. However, there exists the possibility of cancer development due to accumulated doses as suggested by the excess lifetime cancer risk values. Keywords : Background radiation levels, absorbed doses, farm lands, Ishielu communities

GIS mapping of impact of industrial activities on the terrestrial background ionizing radiation levels of Ughelli metropolis and its environs, Nigeria

Abstract: The assessment of industrial activities and effluents on the external background ionizing radiation (BIR) levels of Ughelli metropolis and its environs has been conducted, using a digilert 100 nuclear radiation monitor and geographical positioning system for GIS mapping. The monitoring of the terrestrial BIR levels was carried out for 2 years (from May 2013 to June 2015) in 21 locations within the city and 21 other major villages/towns in Ughelli North local government area of Delta state. Measured exposure rate in Ughelli metropolis revealed a mean value of 15.20 ± 2.80 µRh−1 (1.28 ± 0.23 mSvy−1), while a mean value of 15.19 ± 2.70 µRh−1 (1.28 ± 0.23 mSvy−1) was obtained in the villages/towns. The estimated mean outdoor absorbed dose rate for the Ughelli metropolis and Ughelli environs is 132.16 ± 24.36 ηGyh−1 and 132.15 ± 23.50 ηGyh−1, respectively. The mean annual effective dose equivalent is 0.16 ± 0.03 mSvy−1) while the mean excess life cancer risk is (0.56 ± 0.11) × 10−3 mSvy−1. GIS maps of the study area revealing the BIR distribution and higher radiation levels were recorded in areas/communities where there are industrial activities and oil and gas facilities. The overall results of the measured exposure rates and the estimated radiological indices show that 73.5% of the sampled location exceeded their permissible limits. The mean equivalent dose rate obtained is higher than the safe exposure limit of 1.0 mSvy−1) recommended by UNSCEAR, and the mean radiation exposure levels in the study area is well above the normal background radiation level of 13.00 µRh−1 which shows that the studied area is radiologically contaminated. Though these values obtained may not cause immediate health hazard, there is the likelihood of long-term accumulating health side effects on the residents of some of these locations and communities sampled. Recommendations are made on the possible ways of reducing the impacts on the populace.

Natural Radioactivity in Soil, Associated Radiation Exposure and Cancer Risk to Population of Eastern Haryana, India

Abstract: This study was undertaken to quantify the natural radioactivity in soil and associated radiation exposure to the inhabitants residing in Sonipat district, Haryana, India. A total of 120 soil samples were collected from 30 villages. These soil samples were quantified for naturally occurring radioactive materials activity using HPGe detector. Activity concentration of 40K, 232Th and 226Ra in the soil samples of study area ranged from 463.8–696.9 Bq kg−1, 31.4–37.9 Bq kg−1and 41.5–54.9 Bq kg−1, respectively. Radium equivalent (Raeq) values of all samples are lesser than maximum permissible limit (370 Bq kg”1) acceptable for safer use of soil as building material. Average value of Air absorbed dose (AAD) in the study area was comparable to the Indian average of 64 nGy h−1. Annual effective dose equivalent (AEDE) in the study area was 0.0831 µSv y−1 that is lower than the global average of 70.0 µSv y−1. Annual Gonadal equivalent dose in study area was within the safe limit (1 µSv y−1). Excess life time cancer risk due to natural radioactivity of soil to population of area is negligibly small. Values of Gamma index (Ia), outside hazard index (Hex) and inside hazard index (Hin) are less than unity, indicating that there is no considerable health risk caused by natural radioactivity in soil in the study area.

Sources of monazite patches and dynamics of radionuclides concentration in the high background radiation areas of Kollam District, Kerala

Abstract: The present study attempts to provide a proper explanation to define the monazite source region and reason for its enrichment in coastal belts of Kollam district, Kerala. As part of that, primary data on enrichment of naturally occurring radionuclides viz. 40K, 226Ra, and 232Th in sand samples were collected from the study area and has been measured using NaI(Tl) detector. The radiological parameters were also calculated and compared with the Indian and World average values suggested by the UNSCEAR. The local variations in enrichment then connected with local lithology, drainage and sea wave direction for understanding the source and path of distribution. Connecting the dynamics of radioactivity concentration in a Geospatial study had finally provided details on source and locations of the parent material.