Radionuclides In Surface Soil Research Articles

Assessment of naturally occurring radionuclides in surface soil and drinking water from western part of Yadgir district Karnataka, India.

Radionuclide activity of the selected radionuclides 238U, 232Th and 40K was measured in surface soil samples collected from 40 villages of the western part of Yadgir district of Karnataka. A 4″×4″ NaI (Tl) detector based on a gamma spectrometer is used for the estimation of radionuclides. The major type of soil in this region is sandy and red. The 222Rn activity concentrations in drinking water were determined by the Emanometry method. The 222Rn activity in ground water is found to vary from 1.73 to 155.6Bql-1. The total annual effective doses because of 222Rn inhalation and ingestion range from 4.72 to 424.84μSv y-1 with an average value of 108.8μSv y-1, respectively. Among the sampling stations, Shahapur and Shorapur soil samples show higher activity values than the Kembhavi and Hunasagi sampling stations soil samples.

Geochemical distributions of natural radionuclides in surface soils and sediments impacted by lead-zinc mining activity

This study investigated the distribution features of uranium-238 (238U), radium-226 (226Ra), thorium-232 (232Th), and potassium-40 (40K) and evaluated the associated environmental radiological hazards of the topsoil and river sediments in the Jinding lead-zinc (Pb-Zn) mine catchment from Southwest China. The activity concentrations of 238U, 226Ra, 232Th, and 40K ranged from 24.0 ± 2.29–60.3 ± 5.26 Bq.kg-1, from 32.5 ± 3.95–69.8 ± 3.39 Bq.kg-1, from 15.3 ± 2.24–58.3 ± 4.92 Bq.kg-1, and from 203 ± 10.2–1140 ± 27.4 Bq.kg-1, respectively. The highest activity concentrations for all these radionuclides were primarily found in the mining areas and decreased with increasing distance from the mining sites. The radiological hazard indices, including radium equivalent activity, absorbed gamma dose rate in the air, outdoor annual effective dose equivalent, annual gonadal dose equivalent, and excess lifetime cancer, revealed that the highest values were observed in the mining area and downstream, specifically in the vicinity of the ore body. These elevated values exceeded the global mean value but remained below the threshold value, suggesting that routine protection measures for Pb-Zn miners during production activities are sufficient. The correlation analysis and cluster analysis revealed strong associations between radionuclides such as 238U, 226Ra, and 232Th, indicating a common source of these radionuclides. The activity ratios of 226Ra/238U, 226Ra/232Th, and 238U/40K varied with distance, suggesting the influence of geological processes and lithological composition on their transport and accumulation. In the mining catchment areas, the variations in these activity ratios increased indicated the impact of limestone material dilution on the levels of 232Th, 40K, and 238U in the upstream region. Moreover, the presence of sulfide minerals in the mining soils contributed to the enrichment of 226Ra and the removal of 238U caused those activity ratios decreased in the mining areas. Therefore, in the Jinding PbZn deposit, the patterns of mining activities and surface runoff processes in the catchment area favored the accumulation of 232Th and 226Ra over 40K and 238U. This study provides the first case study on the geochemical distributions of natural radionuclides in a typical Mississippi Valley-type PbZn mining area and offers fundamental information on radionuclide migration and baseline radiometric data for PbZn deposits worldwide.

Natural Radionuclides in Surface Soil and Quantification of Associated Radiological Hazards in Fatehabad and Hisar districts, Haryana, India

Natural Radionuclides in Surface Soil and Quantification of Associated Radiological Hazards in Fatehabad and Hisar districts, Haryana, India

Radiological Risks from Natural Radionuclides in Surface Soil of Agbara Industrial Area, Ogun State, Nigeria

Measurement of natural radioactivity in soil samples from the Agbara Industrial area, Nigeria, was measured using gamma-ray spectrometry with NaI (Tl) detector. The concentration of 238U ranged from 10.21±3.50 to 67.41±18.2 Bqkg-1, from 26.43±10.8 to 96.24±18.81 for 232Th and from 298.65±60.70 to 840.52±150.25 Bqkg-1 for 40K. Their means were, respectively, 28.69±11.00, 45.86±10.25, and 481.22±106.17 Bqkg-1 . Annual effective varies from 0.08 to 0.16 mSv y-1 with a mean of 0.11 mSv y-1. The mean contamination factor was 0.87 for 228Ra, 1.02 for 232Th and, 1.15 for 40K.The soil is moderately polluted with 232Th and 40K. The Pollution Level Index indicates a drop in soil quality in about 50% of the areas covered. The mean cancer risk (0.4 x 10-3 ) obtained in this study is above the World Health Organization limit, indicating a high probability for inhabitants to develop lung cancer in the long term when a lifetime is spent in this area under study.

Investigations of environmental radioactivity in the northern state of Sudan

Investigations have been carried out for naturally occurring radionuclides in surface soils in selected regions of the Northern State of Sudan, in response to widely spread rumours of elevated levels of radioactivity causing higher than normal incidence of cancer in that area. Eighty surface soil samples were collected from different regions in the Northern State and their activity concentrations were measured by a high-purity germanium detector gamma spectrometer system. From the data obtained the mean values and standard deviations of the radionuclide activities were calculated. From the activity concentrations of 226Ra, 232Th and 40K radionuclides the external absorbed dose rate in air and the annual effective dose were calculated.The radium equivalent activity and the external hazard index were applied for estimating the radiation hazards of soil used as building material. The mean activity concentrations of 226Ra, 232Th and 40K in different regions of the Northern State were found to be 82.6 + 6.8, 26.0 + 2.9 and 726.4 + 72.0 Bq/kg, respectively.The average outdoor gamma absorbed dose rate in air at 1meter above ground was calculated as 84.6 + 7.1 nGy/h. The average annual effective dose equivalent for population in the regions under study was found to be 103.7 + 8.7 Sv/y. The external hazard index was found to be 0.48 + 0.04.

Radiological Risk Assessment of Oil waste in the Oilfields at Zubair district of Basrah

The specific activities of natural radionuclides in several samples were collected from the areas that exposed to triple-aggression which is Zubair province at Basrah governorate exactly. Those samples were studied and that concentrations calculated by using Gamma spectrometry system based on HpG detector with efficiency 40% was used for analysis of NORM. Then radiological risk of the natural radioactivity was estimated for study area that caused from exist the radionuclides in surface soil and water samples. The results have been revealed the contamination that occurring in some sites of Zubair district belonging to the natural radioactive material. Activity concentrations in Bq/kg of 238U, 232Th, and 40K with mean values of 95.8 Bq/kg, 31.6 Bq/kg, and 482.18 Bq/kg respectively. The outcome of soil samples were appeared higher values when compared with international calibrations. Whereas the results of Gamma absorbed dose (nGry/h), the exposure dose rate (µR/h) have mean values non-detected like; 52.5, 12.8 respectively, where under the international average by UNSCEAR 2008. Since the Radium equivalent activity (Ra-eq) has value 295.8 Bq/kg is higher than the standardizations.

Measurement of radionuclides in surface soil and beach sand samples from Rayong Province (Thailand) and the evaluation of excess lifetime cancer risk

Measurement of radionuclides in surface soil and beach sand samples from Rayong Province (Thailand) and the evaluation of excess lifetime cancer risk

Risk assessment of human exposure to radionuclides in soil of urban areas (public parks and open playgrounds) in Krusevac, Serbia

This study aims to obtain data on terrestrial radioactivity coming from naturally occurring (40K, 226Ra, 232Th, and 238U) and artificial (137Cs) radionuclides in surface soil (0-10 cm) of selected eighteen public-access urban areas in Krusevac city, Serbia, and to assess the corresponding health effects for citizens using those areas for recreational purposes. The specific activities of investigated radionuclides were analyzed using HPGe gamma-ray spectrometry. The mean specific activity of 40K, 226Ra, 232Th, 238U, and 137Cs was found to be 353, 39.8, 38.9, 41.0, and 5.9, respectively, in compliance with their values in other parts of Serbia and neighboring countries reported in similar researches. To evaluate the human health risk associated with radionuclides, conservative exposure assumptions and models recommended by the United States Environmental Protection Agency were employed taking into account three exposure routes: ingestion, inhalation of soil, and external irradiation. The absorbed gamma dose rate in the air due to natural radionuclides in soil was calculated. The calculated indices suggested that the radiation risk arising from natural and artificial radionuclides was not significant. The total excess lifetime cancer based on the 95 % upper confidence limit of the specific activities mean was calculated to be 5.89?10?6, lower than the tolerable risk for regulatory purposes (10?4). Among investigated radiation exposure pathways, external exposure was the most contributing one for the health risk. The results obtained for the city's parks and playgrounds suggested their safe use for recreational purposes from the radioecological point of view.

‘Time to crop’ for 137Cs in the surface soil and its long-term effects to population based on model assessment

Long-term behavior of artificial radionuclides in surface soils is very important to assess the radiological effects to population. Among artificial radionuclides, 137Cs is most important because of its long half-life and its biggest abundance in the environment. In this study, the fate of 137Cs in the surface soil layers was assessed by the Canadian Centre for Environmental Modelling and Chemistry (CEMC) soil model which is well known as a simple assessment of the relative potential for degrading reaction, evaporation, and leaching of a pesticide applied to a surface soil. The total decrease rate of 137Cs activity concentration in the surface soil (Te1/2) was 10.4 years found in the top 0–5 cm of the soil layer. The activity decrease of 137Cs and the corresponding Te1/2 values under the different depths of surface soil layer were investigated. The influences of soil organic material, soil water content and soil porosity to the losing rate of 137Cs were considerable. Long-term effects of 137Cs to population were assessed through activity concentrations of 137Cs in any parts of the food chain. Soil-to-plant transfer factor (TF), transfer coefficients Fm (transfer to animal milk) and Ff (transfer to animal meat) collected from many literatures were used for activity calculation. The effective doses to population due to ingestion of edible parts of plants, milk and meat was evaluated. The incorporation of four terms: radiological doses, soil-to-plant transfer factors (TF), plant-to-animal coefficients (Fm and Ff) and the total decrease rate of 137Cs is the new approach. The new concept ‘Time to crop’ (TC) based on the effective doses to population was explored and first used for agricultural proposals in the topsoils of the 137Cs exclusion zone. TC was calculated for many scenarios of radioactive exposures, many type of plants, animals and plant groups. TC values were found various in order fruits < leafy vegetables < tubers < cereals < grasses. The highest TC was found for grasses group as a result of the long-term accumulation of radionuclides in animals.

Study on the characteristics of natural radionuclides in surface soil in Ho Chi Minh City, Vietnam and radiological health hazard

The activity concentration of the natural radionuclides 232Th, 238U, and 40K in soil samples collected from different locations of Ho Chi Minh City, Vietnam was measured. At District 1, the average activity concentration of primordial radionuclides 232Th, 238U, and 40K were 25 ± 2, 33 ± 1, and 215 ± 7 Bq kg−1, respectively. At District 5, the corresponding values were 22 ± 1, 23 ± 1, and 198 ± 6 Bq kg−1, respectively. The external hazard index and annual effective dose were found within the safety limitation of UNSCEAR. The cancer risk of people living in District 1 was slightly higher than District 5, with average value of (168 ± 5) 10−6 Sv−1 in District 1 and (133 ± 4) 10−6 Sv−1 in District 5. Th/K ratio was calculated for studying the geological characteristics. The results indicated that two main types of soil are kaolinite and montmorillonite.

Ardahan ili ve çevresindeki toprak örneklerindeki ortalama etkin dozun değerlendirilmesi için doğal radyoaktivitenin analizi

In this study, the distribution of natural radionuclides in surface soils in Ardahan province has been determined. The activity concentrations of 238 U, 232 Th, 40 K and 137 Cs in 35 soil samples collected from the Ardahan city and its surrounded districts were measured through NaI (Tl) gamma spectrometry. The average activities of the samples were determined to be 29.9±6.2, 36.7±6.8 and 435.1±23.9 Bq kg -1 for the natural radionuclides 238 U, 232 Th and 40 K, respectively. For the fission product 137 Cs, the average activity of the samples was assigned to be 15.5±0.8 Bq kg -1 . The average outdoor gamma dose rate (terrestrial and cosmic) and also the average annual effective dose rate in air due to the presence of radionuclides in 35 soil samples were obtained as 56.3±8.7 nGy h -1 and 69.0±6.7 µSv y -1 , respectively. This research showed a clear correlation between the altitude and the natural radionuclides. The results obtained for Ardahan city centrum and its districts were presented graphically and compared with the world average values and those of Turkey.

Radiological monitoring and statistical approach of primordial and anthropogenic radionuclides in surface soil of Mami-water site in the Western Cameroon

The study referred to measure activity concentrations of some primordial radionuclides and anthropogenic of 137Cs in soil samples of Mami-water in the Menoua subdivision, Dschang employing gamma-ray spectrometry-based characterized Broad Energy Germanium (BE6350) detector and a comparison of radiological and safety impact parameters on human due to primordial radioactivity in soil with some internationally approved values. In addition, statistical analysis of primordial radionuclides of 226Ra, 232Th and 40K was performed to evaluate the distribution and the interrelation of radionuclides. Samples were randomly collected from a depth of about 0 to 5 cm from the top surface layer. Each of the sampling points was considered as being overlaid with a grid and subdivided into cells. The observed radioactivity level of 226Ra, 232Th and 40K in the investigated soil samples was compared with some published data available in some countries including Cameroon and observed varying within some reported data of radioactivity in soil from bauxite ore deposit. 235U and 137Cs were found in very few samples with a very low average of activity concentrations. In the majority of the samples, the observed radiological safety parameters seem to be greater than the internationally approved values. Consequently, using bricks made of soil as building materials might lead to an increase in radiation risk for the population. Multivariate statistical analysis of activity concentrations of primordial radionuclides performed showed an asymmetrical distribution with more peaked than Gaussian distribution and relatively flatter distribution of radionuclides in soil. In addition, a good positive interrelation between 226Ra and 232Th was observed and a weak negative one observed between 40K and 226Ra–232Th.

Plutonium, 137Cs and uranium isotopes in Mongolian surface soils

Plutonium (238Pu and 239,240Pu), 137Cs and plutonium activity ratios (238Pu/239,240Pu) as did uranium isotope ratio (235U/238U) were measured in surface soil samples collected in southeast Mongolia. The 239,240Pu and 137Cs concentrations in Mongolian surface soils (<53 μm of particle size) ranged from 0.42 ± 0.03 to 3.53 ± 0.09 mBq g−1 and from 11.6 ± 0.7 to 102 ± 1 mBq g−1, respectively. The 238Pu/239,240Pu activity ratios in the surface soils (0.013–0.06) coincided with that of global fallout. The 235U/238U atom ratios in the surface soil show the natural one. There was a good correlation between the 239,240Pu and 137Cs concentrations in the surface soils. We introduce the migration depth to have better understanding of migration behaviors of anthropogenic radionuclides in surface soil. We found a difference of the migration behavior between 239,240Pu and 137Cs from 137Cs/239,240Pu – 137Cs plots for the Mongolian and Tsukuba surface soils; plutonium in surface soil is migrated easier than 137Cs.

Measurement of long-lived radionuclides in surface soil around F1NPP accident site by Accelerator Mass Spectrometry

In March 2011, vast amounts of radionuclides were released into the environment due to the Fukushima Daiichi Nuclear Power Plant (F1NPP) accident. However, very little work has been done concerning accident-derived long-lived nuclides such as 129I (T1/2=1.57×107year) and 36Cl (T1/2=3.01×105year). 129I and 131I are both produced by 235U fission in nuclear reactors. Being isotopes of iodine, these nuclides are expected to behave similarly in the environment. This makes 129I useful for retrospective reconstruction of 131I distribution during the initial stages of the accident. On the other hand, 36Cl is generated during reactor operation via neutron capture reaction of 35Cl, an impurity in the coolant or reactor component. Resulting 36Cl/Cl ratio within the reactor is thus much higher compared to that in environment. Similar to 129I, 36Cl is expected to have leaked out during the accident and it is important to evaluate its effects. In this study, 129I concentrations were determined in several surface soil samples collected around F1NPP. Average 129I/131I ratio was estimated to be 26.1±5.8 as of March 11, 2011, consistent with calculations using ORIGEN2 code and other published data. 36Cl/Cl ratios in some of the soil samples were likewise measured and ranged from 1.1×10−12 to 2.6×10−11. These are higher compared to ratios measured around F1NPP before the accident. A positive correlation between 36Cl and 129I concentration was observed.

Determination of natural radioactivity levels in Kars- city center, Turkey

The objective of this study is to determine the distribution of natural radionuclides in surface soils in the Karscity center, Turkey. The activity concentrations of 238U, 232 Th, 40 K and 137Cs in 38 soil samples collected from the study area were measured through NaI(Tl) gamma spectrometry. The average activities of the samples were determined to be 47.8, 31.2 and 536 Bqkg-1 for the natural radionuclides 226Ra (238U), 232Th, 40K, respectively, and 18 Bqkg-1 for the fission product 137Cs. When the present results are compared with the data available for other cities in Turkey, the soil radioactivity concentrations obtained in this study indicate that the region has a background radiation level within natural limits but the measured average activity of 40K depending on soil texture is slightly higher than the other parts of country

Lithogenic radionuclides in surface soils of Serbia: Spatial distribution and relation to geological formations

The survey results of concentrations of lithogenic radionuclides in surface soils from 213 locations in Serbia, their mutual concentration ratios and spatial distribution are presented. The mean concentrations of uranium, thorium and potassium in soils of 2.6mgkg−1, 9.3mgkg−1 and 1.8·104mgkg−1, respectively, were found to be similar with equivalent values reported for soils of regions with similar geological composition and geotectonic structures and also with worldwide average values. The spatial distribution of analyzed radionuclides was geostatistically interpolated using ordinary kriging. The spatial distribution maps of uranium, thorium and potassium concentrations showed their variability among different regions as a consequence of different lithological units of the investigated area.

Distribution of radionuclides in surface soils, Singhbhum Shear Zone, India and associated dose

Gamma emitters were estimated in surface soils from a mineralized zone in Eastern India using high purity Germanium detector-based high resolution gamma spectrometry system. Activities of (238)U, (226)Ra, (232)Th, (235)U, (227)Th, (234 m)Pa, (210)Pb, (40)K, and (137)Cs were 79 ± 50, 81 ± 53, 65 ± 23, 4 ± 2, 5 ± 4, 92 ± 50, 97 ± 45, 517 ± 201, and 4 ± 2 Bq/kg, respectively. Most radionuclides were observed to follow log-normal distribution. The correlation between physicochemical properties of the samples, like pH, organic matter content, particle size, and moisture content were also studied. Activity ratios of (226)Ra/(238)U, (210)Pb/(226)Ra, and (227)Th/(235)U indicated deviation from secular equilibrium in some samples. The associated annual effective dose ranged from 0.07 to 0.24 mSv and the mean was calculated to be 0.12 ± 0.04 mSv for this region, indicating it to be one of normal natural background radiation.

Introduction to the special issue ‘Tracer Applications in Sediment Research’

Introduction to the special issue ‘Tracer Applications in Sediment Research’

Distribution of terrestrial and anthropogenic radionuclides in Turkish surface soil samples

A comprehensive study was executed to determine the distribution of the natural and anthropogenic radionuclides in surface soils throughout Turkey. In this study, the activity concentrations of 238U, 232Th, 40K and 137Cs in total of 1031 soil samples collected from seven geographical regions of Turkey were measured using the high-resolution gamma spectrometer with HPGe detector. The activity concentrations of 238U, 232Th, 40K and 137Cs in soil samples varied from 2.0 to 220.0Bqkg−1 with a mean of 28.6±0.7Bqkg−1, 1.0 to 158.6Bqkg−1 with a mean of 33.0±0.7Bqkg−1, 26.0 to 1603.2Bqkg−1 with a mean of 448.5±7.3Bqkg−1 and 1.0 to 357.0Bqkg−1 with a mean of 13.4±0.8Bqkg−1, respectively. Elemental concentration mean values of 238U, 232Th and 40K were found as 2.3mgkg−1, 8.1mgkg−1 and 1.4%, respectively. For all surface soil samples the absorbed gamma dose rate and the corresponding effective dose rate due to the external exposure in outdoor were evaluated as 51.9 nGy h−1 (4.7–234.3 nGy h−1) and 0.064mSv y−1 (0.006–0.287mSv y−1), respectively.

Distribution of natural radionuclides in surface soils in the vicinity of abandoned uranium mines in Serbia

The activity concentrations of natural radionuclides in soils from the area affected by uranium mining at Stara Planina Mountain in Serbia were studied and compared with the results obtained from an area with no mining activities (background area). In the affected area, the activity concentrations ranged from 1.75 to 19.2 mg kg(-1) for uranium and from 1.57 to 26.9 mg kg(-1) for thorium which is several-fold higher than those in the background area. The Th/U, K/U, and K/Th activity ratios were also determined and compared with data from similar studies worldwide. External gamma dose rate in the air due to uranium, thorium, and potassium at 1 m above ground level in the area affected by uranium mining was found to be 91.3 nGy h(-1), i.e., about two-fold higher than that in background area. The results of this preliminary study indicate the importance of radiological evaluation of the area and implementation of remedial measures in order to prevent further dispersion of radionuclides in the environment.