Concentrations Of Radionuclides In Samples Research Articles

RADIOACTIVITY OF SOIL IN THE REGION OF THE TOWN OF NIŠ, SERBIA.

The concentration of radionuclides in samples of soil collected in the region of the town of Niš, was measured and presented in this paper. The naturally occurring radionuclides, 226Ra, 232Th and 40K, were found in all samples. In many of them, 137Cs was also measured, while the other artificial radionuclides were not detected. The measurements were carried out using the standard gamma spectroscopy system with high purity germanium (HPGe) detector. The results show that the average activity concentrations of 226Ra, 232Th, 40K and 137Cs are: 21, 26, 414 and 4.7, in Bq/kg, respectively. The sediment in the municipality spa Niška Banja exhibits a high content of 226Ra, 573 Bq/kg. The outdoor dose rates, due to the gamma radiation of the ground, were also determined for all soils. The average absorbed dose rate in air was estimated to be 39 nGy/h, while the corresponding annual effective dose is 0.048 mSv.

A survey of natural terrestrial and airborne radionuclides in moss samples from the peninsular Thailand

The aim of this study was to determine the activity concentrations of natural terrestrial radionuclides (238U, 226Ra, 232Th and 40K) and airborne radionuclides (210Pb, 210Pbex and 7Be) in natural terrestrial mosses. The collected moss samples (46) representing 17 species were collected from 17 sampling localities in the National Parks and Wildlife Sanctuaries of Thailand, situated in the mountainous areas between the northern and the southern ends of peninsular Thailand (∼7–12 °N, 99–102 °E). Activity concentrations of radionuclides in the samples were measured using a low background gamma spectrometer. The results revealed non-uniform spatial distributions of all the radionuclides in the study area. Principal component analysis and cluster analysis revealed two distinct origins for the studied radionuclides, and furthermore, the Pearson correlations were strong within 226Ra, 232Th, 238U and 40K as well as within 210Pb and 210Pbex, but there was no significant correlation between these two groups. Also 7Be was uncorrelated to the others, as expected due to different origins of the airborne and terrestrial radionuclides. The radionuclide activities of moss samples varied by moss species, topography, geology, and meteorology of each sampling area. The observed abnormally high concentrations of some radionuclides probably indicate that the concentrations of airborne and terrestrial radionuclides in moss samples were directly related to local geological features of the sampling site, or that high levels of 7Be were most probably linked with topography and regional NE monsoonal winds from mainland China.

Assessment of radiation hazards a result of natural radioactivity in water from Abyan delta, Yemen

This paper presents the concentrations of naturally occurring radionuclides 226Ra, 232Th and 40K measured in Groundwater collected from Abyan delta on Gulf of Aden in Yemen. Concentrations of radionuclides in samples were determined by gamma-ray spectrometer using HPGe detector with specially designed shield. The average activity concentrations were (1.71 ± 0.09 Bq l−1), (1.43 ± 0.05 Bq l−1) and (14.16 ± 0.45 Bq l−1) for 226Ra, 232Th and 40K, respectively. The annual effective doses mSv y−1 due to ingestion of 226Ra and 232Th for different age groups were also calculated. The results compared with the recommended value reported by World Health Organization.

Dose assessment to public due to exposure to natural radioactivity at the Bibiani gold mine

Studies have been carried out to assess exposure of the public due to natural radioactivity associated with soil, tailing and water at the Bibiani gold mine in Ghana. Concentrations of radionuclides in samples were determined by γ-ray spectrometry using high purity germanium detector. Gross-α and gross-β activity concentrations were also determined for the water samples using a low background gas-less automatic α/β counter. The mean activity concentrations of 238U, 232Th and 40K in soil/tailing samples were 16.1 ± 3.6, 16.6 ± 6.0 and 380 ± 15 bq/kg, respectively. The mean activity concentrations in water samples were 0.20 ± 0.04, 0.38 ± 0.03 and 3.05 ± 0.11 Bq/L for 226Ra, 232Th and 40K respectively. The total annual effective dose to the public was estimated to be 0.125 mSv. The radium equivalent activity, internal hazard index, and external hazard index for all soil/tailing samples are lower than the accepted safety limit value of 370 Bq/kg and 1.0 respectively. The gross-α and gross-β activity concentrations for the water samples were below the World Health Organisation recommended guideline values for drinking water quality. The results indicate an insignificant radiation exposure to the public.

Radionuclide concentrations in samples of medicinal herbs and effective dose from ingestion of 137Cs and natural radionuclides in herbal tea products from Serbian market

The objective of this study is to evaluate natural and artificial radioactivity levels in 18 different samples of medicinal herbs from Serbian market. The activity concentrations of 238U, 232Th, 40K, and 137Cs were measured using gamma spectroscopy system with a high-purity germanium detector. The activity concentrations of 238U, 232Th, 40K, and 137Cs were found to be in a range of 0.6–8.2, 1.7–15.1, 126–1243.7, and 0.3–8.8 Bq/kg, respectively. The annual whole body doses from ingestion of 137Cs and natural radionuclides for an adult person who consumed herbal tea from these medicinal herbs were found to be 2.5–469.9 nSv for 137Cs, 0.7–9.7 nSv for 238U, 0.3–2.8 nSv for 232Th, and 1026.0–10,132.0 nSv for 40K. These doses are not hazardous to public health. The obtained results were compared with correspondent studies conducted worldwide.

Assessment of natural and anthropogenic radioactivity levels in rocks and soils in the environments of Juban town in Yemen

The natural radioactivities of 40K, 226Ra, and 232Th and the fallout of 137Cs in rock and soil samples collected around Juban town in Yemen (south west of Asia) were measured. Concentrations of radionuclides in samples were determined by gamma-ray spectrometer using HPGe detector with specially designed shield. The average radioactivity concentrations of 226Ra, 232Th, and 40K were determined expressed in Bq/kg. The results show that these radionuclides were present in concentrations of (53.6±4, 127±6.7, and 1742.8±62 Bq/kg), (55±4, 121±6.6, and 2341±78 Bq/kg), (212.8±8.7, 109 ±5.5, and 32.4±4.7 Bq/kg), and (32.1±3, 22.3±2.9 and 190.9±15 Bq/kg) for granite, gneiss, siltstone, and sandstone rocks, respectively. For soil the corresponding values were 44.4±4.5, 58.2±5.1, and 822.7±31 Bq/kg. Low deposits of 137Cs were noted in investigation area, where the activity concentrations ranged from 0.1±0.1 to 23.2±1.2 Bq/kg. Also the radiological hazard of the natural radionuclides content, radium equivalent activity, total dose rates, external hazard index, and gamma activity concentration index of the (rocks/soils) samples in the area under consideration were calculated. The data were discussed and compared with those given in the literature.

Natural radionuclides in sediments and rocks from Adriatic Sea

During the International Scientific Cruise to Adriatic and Ionian Seas organised by the International Atomic Energy Agency, sediment and rock samples were collected. Sediments were sampled with grab corer at six locations in the Southeast Adriatic Sea. Rocks were col- lected on three islets in the Adriatic Sea. In the samples, natural radionuclides 238 U, 234 U, 232 Th, 230 Th, 226 Ra and 210 Pb were determined. After sampling and sample prep- aration, radiochemical separation procedures were applied. Then the samples were measured by alpha spectrometry system equipped with passivated implanted planar silicon detectors or by low background gas-flow proportional counter. Activity concentrations of natural radionuclides in samples were from 6.2 to 27.0 Bq/kg for 238 U, from 7.9 to 28.1 Bq/kg for 234 U, from 1.6 to 31.9 Bq/kg for 232 Th, from 9.7 to 42.0 Bq/kg for 230 Th, from 8.3 to 45.7 Bq/kg for 226 Ra and from 3.0 to 113.4 for 210 Pb. The obtained

Radionuclide Contents and Physicochemical Water Quality Indicators in Stream, Well and Borehole Water Sources in High Radiation Area of Abeokuta, Southwestern Nigeria

Water samples from streams, hand-dug wells and boreholes in high background radiation areas in Abeokuta, Nigeria have been collected in order to determine the activity concentrations of 40K, 226Ra and 232Th in the samples as well as their physicochemical characteristics. These parameters were evaluated in order to deter-mine the quality of these water sources to the local population, who use these water resources for drinking and domestic activities. Measurements of radioactivity in the water samples were carried out using γ-ray spectroscopy, while standard chemistry methods were used for the physicochemical determinations of these quality parameters. A total of fourteen representative water samples from streams (7), boreholes (4), and hand dug wells (3) were collected for study. The determined activity concentrations of the radionuclides in these samples were used to calculate the effective dose to the population from due to ingestion of and drink-ing the locally available water. The total annual ingestion effective doses were found to vary between 115.00 ± 1.15μSv and 1362.30 ± 438.02 μSv. The physicochemical parameters where found to be lower than the prescribed standard safe limits in the water sources except for the nitrate and phosphate levels which were particularly high in the water samples from boreholes and hand-dug wells. The radiation effective ingestion dose due to ingestion of water from dug wells and streams was found to be higher than the dose due to inges-tion of water from borehole sources in the studied areas. The results obtained in this study, have been taken as a baselines for physicochemical parameters and activity concentrations of natural radionuclides in water samples within Odeda and Obafemi-owode parts of Abeokuta, Nigeria.

Uranium and thorium in soils, mineral sands, water and food samples in a tin mining area in Nigeria with elevated activity

The activity concentrations of uranium and thorium have been determined in soils and mineral sands from the Nigerian tin mining area of Bisichi, located in the Jos Plateau, and from two control areas in Nigeria (Jos City and Akure) using high-purity germanium detectors (HPGe). High resolution sector field inductively coupled plasma mass spectroscopy (HR-SF-ICP-MS) was used to determine uranium and thorium in liquids and foodstuffs consumed locally in the mining area. The activities of uranium and thorium measured in the soils and mineral sands from Bisichi ranged from 8.7 kBq kg −1 to 51 kBq kg −1 for 238U and from 16.8 kBq kg −1 to 98 kBq kg −1 for 232Th, respectively. These values were significantly higher than those in the control areas of Jos City and Akure and than the reference values reported in the literature. They even exceeded the concentrations reported for areas of high natural radioactive background. Radionuclide concentrations in samples of the local foodstuffs and in water samples collected in Bisichi were found to be higher than UNSCEAR reference values. The results reveal the pollution potential of the mining activities on the surrounding areas.

Towards more precise 10Be and 36Cl data from measurements at the 10 −14 level: Influence of sample preparation

The spreading application of accelerator mass spectrometry (AMS) to the geosciences will require measurement of increasing numbers of samples with low 10Be/ 9Be and 36Cl/Cl isotopic ratios. To distinguish radionuclide concentrations in samples from corresponding processing blanks, samples must be prepared using stable isotope carriers with low intrinsic radionuclide concentrations. Measurements at different AMS facilities have shown that commercially available 9Be carriers rarely meet these requirements and use of 9Be carriers prepared from Be-containing minerals such as Be 2SiO 4 is advisable. For precise determinations at the low 10 −14 level, samples need to produce the highest 9Be currents possible. Measurements performed at the two AMS facilities in France show that mixing BeO with Nb powder generally yields higher 9Be currents than mixing with Ag powder. Contamination of BeO by other elements such as Ti or Al will reduce the current by a simple dilution effect, thus limiting the statistical precision with which 10Be can be determined. In the case of 36Cl analyses, repeated water-leaching of calcite samples sufficiently removes all atmospheric 36Cl contamination, allowing determination of terrestrial cosmogenic in situ produced 36Cl concentrations for surface exposure dating.

Activity levels of 137Cs and 40K in the skin and the cutaneous organs of a cow.

We have performed an extensive study to determine the activity distributions of radiocesium (137Cs) and of the radioisotope 40K of potassium in the whole body of a cow. ICRP assumes that cesium and potassium are distributed homogeneously throughout the whole body of an organism. The current investigation measured concentrations of 137Cs and 40K in components of the skin, horns, and hooves of a cow. Activity levels of 137Cs were caused by the long-term ingestion following the Chernobyl fallout, whereas the naturally occurring potassium (40K) is an essential part of cow's normal diet. The cow was born at the time of the fallout following the Chernobyl accident and had ingested heavily contaminated forage during its entire lifetime. Activities of 137Cs and 40K were determined simultaneously by gamma spectrometry. All activities are related to the day of slaughter and include also corrections for self attenuation of photons caused by the different densities of the samples. Radionuclide concentrations in samples were corrected for moisture losses incurred during freezing and sample preparation. Surface contamination on the skin was estimated by rinsing it in heated water followed by removal of the epidermis and hair. In comparison with the activities of the components of the skin we observed a considerable amount of external contamination on the surface of the skin. But with respect to whole body countings of the animal this amount of external contamination appears to be negligible. It was found that activity ratios of 137Cs to 40K are greater than 1 in all measured components. The average activity concentrations of 137Cs and 40K in the common integument are 23.3 Bq kg(-1) and 13.3 Bq kg(-1), respectively. The highest activity concentrations of 137Cs and 40K were measured in clean hair and hypodermis. Despite being its largest organ, the cow's skin contains probably less than 1% of the animal's whole body 137Cs activity.

Natural radioactivity and radon exhalation rate of soil in southern Egypt

The level of natural radioactivity in soil of 30 mining samples collected from six locations in southern Egypt was measured. Concentrations of radionuclides in samples were determined by γ-ray spectrometer using HPGe detector with a specially designed shield. The obtained results of uranium and thorium series as well as potassium (K-40) are discussed. The present data were compared with data obtained from different areas in Egypt. Also, a solid state nuclear track detector SSNTD (Cr-39) was used to measure the radon concentration as well as exhalation rate for these samples. The radon concentrations were found to vary from 1.54 to 5.37 Bq/kg. The exhalation rates were found to vary from 338.81 to 1426.47 Bq/m 2d. The values of the radon exhalation rate are found to correspond with the uranium concentration values measured by the germanium detector in the corresponding soil samples.

Radionuclide Content of Building Materials and Gamma Ray Dose Rates in Dwellings of Rio Grande Do Norte, Brazil

Thirty five samples of raw materials and building products were collected in the Brazilian state of Rio Grande do Norte. Concentrations of background radionuclides in samples were determined by gamma ray spectrometry with a HPGe detector. The radium equivalent activity in the 35 samples varied from 18.1 Bq.kg −1 (gypsum) to 806.7 Bq.kg −1 (granite). A handheld scintillometer was used for a radiological investigation in 244 dwellings and workplaces built with the materials being surveyed and located in eleven different towns of the state. The average gamma dose rates ranged from 59 nGy.h −1 (Natal) to 149 nGy.h −1 (Santana do Matos)