A total of 30 samples were collected from six different locations from of Abuja Federal Capital Territory (FCT), the administrative capital of Nigeria which is situated in the central part of the country. The samples ...A total of 30 samples were collected from six different locations from of Abuja Federal Capital Territory (FCT), the administrative capital of Nigeria which is situated in the central part of the country. The samples which were thor-oughly prepared following known dosimetry procedures were analyzed for 40K, 238U and 232Th by the method of Gamma ray spectrometry using NaI(TL) detector coupled to a multichannel analyzer. The activity concentrations in the top soils in these locations for 40K, 238U and 232Th range from 301 ± 26.52 to 928.84 ± 80.57, Not detectable (ND) value to 27.68 ± 8.21 and 4.65 ± 1.46 to 22.48 ± 5.26 respectively. The average absorbed dose rate and the annual effective dose equivalent were found to be 40.33 nGyh–1 and 49.46 μSv respectively. The value of annual effective dose equivalent is low compared to the world average of 70 μSv specified by UNSCEAR for an outdoor effective dose, hence the chances of radiological hazards to the health of the populace are generally low.展开更多
The specific activity concentration and the derived Annual Effective Dose(AED) in three types of vernonia cultivated and consumed within and outside Cameroon were measured by means of a well-calibrated high-purity ger...The specific activity concentration and the derived Annual Effective Dose(AED) in three types of vernonia cultivated and consumed within and outside Cameroon were measured by means of a well-calibrated high-purity germanium detector. Vernonia samples were collected directly from the production farms, oven-dried to a constant mass, crushed, sieved and sealed for at least a month before analysis. The specific activity of 238U in the three types of vernonia ranged from 20 - 50 Bq kg-1 with an average of 42 ± 15 Bq kg-1, 232Th from 9 - 22 Bq kg-1 with an average of 17 ± 7 Bq kg-1 while 40K ranged from 115 - 460 Bq kg-1 with an average of 302 ± 36 Bq kg-1. The average AED for 40K, 238U and 232Th were 0.15, 0.92 and 0.92μSv y-1 respectively. 238U and 232Th show the same trends both for the regional distribution of the radioactivity content and the AED. The discrepancies in our data can be attributed to many factors such as geological formation, foliar deposition, type and age of the plant, etc. Although the results obtained represent only some fractions of the standard limit, but they are within some range obtained in other countries.展开更多
A survey of radioactivity content and associated radiological risks was carried out in various soils used for agriculture and building materials in Cameroon by means of a well-calibrated high-purity germanium detector...A survey of radioactivity content and associated radiological risks was carried out in various soils used for agriculture and building materials in Cameroon by means of a well-calibrated high-purity germanium detector. Soil samples were collected directly from the agricultural farms and the brick’s factories, air-dried at room temperature to a constant mass, crushed, sieved and sealed for at least one month before analysis. The specific activity of 238U ranged from 5.36 ± 0.39 to 51.28 ± 9.67 Bq﹒kg–1 with an average of 34.52 ± 7.18 Bq﹒kg–1;232Th from 4.03 ± 1.03 to 24.74 ± 3.10 Bq﹒kg–1 with an average of 16.67 ± 4.28 Bq﹒kg–1;40K ranged from 16.18 ± 3.11 to 467.40 ± 50.80 Bq﹒kg–1 with an average of 186.96 ± 16.21 Bq﹒kg–1;while that of the fallout 137Cs ranged from 0.00 to 4.79 ± 1.75 Bq﹒kg–1with an average of 2.32 ± 0.99 Bq kg–1;The mean result obtained for the Representative levels index (Iγ), the radium equivalent (Raeq), the total absorbed dose rate (ADR), the external hazard index (Hex), the internal hazard index (Hin) and the Ceasium intervention levels were 0.52, 72.75 Bq﹒kg–1, 33.73 nGy﹒h–1, 0.20 Bq﹒kg–1, 0.29 Bq﹒kg–1 and 0.0028 Bq﹒cm2 respectively. The discrepancies of our data can be attributed to several factors such as past nuclear disasters, geological formation, transport process, etc. Although our results are just some fractions of the international standard limit, but still within the same ranges when compared with those obtained elsewhere. This results also will serve as a baseline data for future investigations.展开更多
A survey of radioactivity concentration in water supplies used for domestic and industrial purposes in the oil and gas producing communities of Delta State, Nigeria was carried out using a well-calibrated High-Purity ...A survey of radioactivity concentration in water supplies used for domestic and industrial purposes in the oil and gas producing communities of Delta State, Nigeria was carried out using a well-calibrated High-Purity Germanium (HPGe) detector system. The study area was partitioned into ten sections and a total of two samples per partition were collected for analysis. Samples of water from a non-producing area were also collected as control. In all, a total number of forty three samples were collected and analyzed. Each sample was acidified at the rate of 10 ml of 11 M HCl per litre of water to prevent the absorption of radionuclides into the wall of the container and sealed in a properly cleaned container for at least one month so as to attain a state of secular radioactive equilibrium before analysis. The photopeaks observed with reliable regularity belong to the naturally occurring series-decay radionuclide headed by 238U and 232Th, as well as the non-series decay type 40K. The mean specific activity obtained for 40K was 49 ± 15 Bq L–1 with a range of 6 - 177 Bq L–1 while for 238U, the mean specific activity was 3 ± 1 Bq L–1 with a range of 1 - 12 Bq L–1 and the mean specific activity for 232Th was 3 ± 2 Bq L–1 with a range of 2 - 10 Bq L–1 and the total annual effective dose, which vary between 0 - 2 μSv y–1, did not show any significant health impact.展开更多
文摘A total of 30 samples were collected from six different locations from of Abuja Federal Capital Territory (FCT), the administrative capital of Nigeria which is situated in the central part of the country. The samples which were thor-oughly prepared following known dosimetry procedures were analyzed for 40K, 238U and 232Th by the method of Gamma ray spectrometry using NaI(TL) detector coupled to a multichannel analyzer. The activity concentrations in the top soils in these locations for 40K, 238U and 232Th range from 301 ± 26.52 to 928.84 ± 80.57, Not detectable (ND) value to 27.68 ± 8.21 and 4.65 ± 1.46 to 22.48 ± 5.26 respectively. The average absorbed dose rate and the annual effective dose equivalent were found to be 40.33 nGyh–1 and 49.46 μSv respectively. The value of annual effective dose equivalent is low compared to the world average of 70 μSv specified by UNSCEAR for an outdoor effective dose, hence the chances of radiological hazards to the health of the populace are generally low.
文摘The specific activity concentration and the derived Annual Effective Dose(AED) in three types of vernonia cultivated and consumed within and outside Cameroon were measured by means of a well-calibrated high-purity germanium detector. Vernonia samples were collected directly from the production farms, oven-dried to a constant mass, crushed, sieved and sealed for at least a month before analysis. The specific activity of 238U in the three types of vernonia ranged from 20 - 50 Bq kg-1 with an average of 42 ± 15 Bq kg-1, 232Th from 9 - 22 Bq kg-1 with an average of 17 ± 7 Bq kg-1 while 40K ranged from 115 - 460 Bq kg-1 with an average of 302 ± 36 Bq kg-1. The average AED for 40K, 238U and 232Th were 0.15, 0.92 and 0.92μSv y-1 respectively. 238U and 232Th show the same trends both for the regional distribution of the radioactivity content and the AED. The discrepancies in our data can be attributed to many factors such as geological formation, foliar deposition, type and age of the plant, etc. Although the results obtained represent only some fractions of the standard limit, but they are within some range obtained in other countries.
文摘A survey of radioactivity content and associated radiological risks was carried out in various soils used for agriculture and building materials in Cameroon by means of a well-calibrated high-purity germanium detector. Soil samples were collected directly from the agricultural farms and the brick’s factories, air-dried at room temperature to a constant mass, crushed, sieved and sealed for at least one month before analysis. The specific activity of 238U ranged from 5.36 ± 0.39 to 51.28 ± 9.67 Bq﹒kg–1 with an average of 34.52 ± 7.18 Bq﹒kg–1;232Th from 4.03 ± 1.03 to 24.74 ± 3.10 Bq﹒kg–1 with an average of 16.67 ± 4.28 Bq﹒kg–1;40K ranged from 16.18 ± 3.11 to 467.40 ± 50.80 Bq﹒kg–1 with an average of 186.96 ± 16.21 Bq﹒kg–1;while that of the fallout 137Cs ranged from 0.00 to 4.79 ± 1.75 Bq﹒kg–1with an average of 2.32 ± 0.99 Bq kg–1;The mean result obtained for the Representative levels index (Iγ), the radium equivalent (Raeq), the total absorbed dose rate (ADR), the external hazard index (Hex), the internal hazard index (Hin) and the Ceasium intervention levels were 0.52, 72.75 Bq﹒kg–1, 33.73 nGy﹒h–1, 0.20 Bq﹒kg–1, 0.29 Bq﹒kg–1 and 0.0028 Bq﹒cm2 respectively. The discrepancies of our data can be attributed to several factors such as past nuclear disasters, geological formation, transport process, etc. Although our results are just some fractions of the international standard limit, but still within the same ranges when compared with those obtained elsewhere. This results also will serve as a baseline data for future investigations.
文摘A survey of radioactivity concentration in water supplies used for domestic and industrial purposes in the oil and gas producing communities of Delta State, Nigeria was carried out using a well-calibrated High-Purity Germanium (HPGe) detector system. The study area was partitioned into ten sections and a total of two samples per partition were collected for analysis. Samples of water from a non-producing area were also collected as control. In all, a total number of forty three samples were collected and analyzed. Each sample was acidified at the rate of 10 ml of 11 M HCl per litre of water to prevent the absorption of radionuclides into the wall of the container and sealed in a properly cleaned container for at least one month so as to attain a state of secular radioactive equilibrium before analysis. The photopeaks observed with reliable regularity belong to the naturally occurring series-decay radionuclide headed by 238U and 232Th, as well as the non-series decay type 40K. The mean specific activity obtained for 40K was 49 ± 15 Bq L–1 with a range of 6 - 177 Bq L–1 while for 238U, the mean specific activity was 3 ± 1 Bq L–1 with a range of 1 - 12 Bq L–1 and the mean specific activity for 232Th was 3 ± 2 Bq L–1 with a range of 2 - 10 Bq L–1 and the total annual effective dose, which vary between 0 - 2 μSv y–1, did not show any significant health impact.
