Determination of (238)U, (232)Th and (40)K activity concentrations in riverbank soil along the Chao Phraya river basin in Thailand

Plutonium isotopes and radionuclides in corals around Weizhou land in Beibu Gulf, China

Plutonium isotopes in the coral were determined with chemical separation method using AG 1-X8 and AG-MP-1M anion exchange resins and sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) in order to elucidate the activity concentration and source of Pu around Weizhou land in Beibu Gulf, China. Furthermore, the activity concentrations of other radionuclides (²³⁸U, ²²⁶Ra, ²³²Th, ¹³⁷Cs, ⁴⁰K and ²¹⁰Pb) were measured by a HPGe spectrometer. The activity concentration of ^240+239Pu in the coral is determined to be in the range of 8.95-27.84 mBq/kg. The ²⁴⁰Pu/²³⁹Pu atom ratios in the samples range from 0.173 to 0.225, indicating that the main source of plutonium in this area is global fallout while the contribution of PPG is about 30%. Further, the activity concentrations of ²³⁸U, ²³²Th, ⁴⁰K and ²²⁶Ra are determined to be in the range of 18.72-64.63, 1.37-20.8, 29.78-72.52 and 3.48-61.97 Bq/kg, respectively.

Baseline thorium concentration and isotope ratios in topsoil of Zacatecas State, Mexico

Thorium is a radionuclide highly widespread in the earth's crust with a relevant contribution to the exposure to radiation of living organisms. Natural concentrations of thorium in the soil can be altered due to human activities such as mining, agriculture, and cattle industry. Mining and related industry have been operating for centuries in Zacatecas State, Mexico, leaving mining waste dumps that can release trace elements to the topsoil. There are not enough previous studies of thorium concentration in this area. Thirty-three soil samples from different locations from Zacatecas State were analyzed, using alpha-spectrometry and ICP-MS, to estimate the reference value for thorium in surface soil in order to provide regulatory agencies with a tool to verify possible disturbances due to anthropogenic activities. Geoaccumulation indexes and enrichment factors did not reveal significant alterations in topsoil thorium concentration. The average concentration was 13.6 ± 7.6 mg kg^-1, which is consistent with the estimated average concentration in the earth crust and is then proposed as average basal concentration for this region. A slight disequilibrium has been found between the natural isotopes of thorium due to the semi-arid nature of the areas and climatic factors.

External radiation exposure of the Angolan population living in adobe houses

This study aims to investigate the radioactivity of adobe in Angola, where it is a widely used building material. Sixty samples have been collected from three remote areas of the country with different geological backgrounds (Cabinda, Huambo, Menongue). Activity concentrations of226Ra,232Th and40K have been determined by gamma-ray spectroscopy and radiation hazard indices were also calculated. The area Huambo shows elevated226Ra and232Th values which can be explained by its older geological formations.40K concentrations are low in general. Regarding external radiation risk, adobe from Angola is safe to use as building material.

Seasonal variations of natural radionuclides, minor and trace elements in lake sediments and water in a lignite mining area of North-Western Greece

The radiological and chemical pollution of a cluster of four lakes in a lignite mining area of North-Western Greece was investigated using a variety of analytical techniques. Alpha spectrometry was applied to measure the activity concentrations of the uranium radioisotopes (U-234, U-235, and U-238) in waters. The mass activities of U-238, Th-232, and K-40 in sediments were measured by high-resolution gamma spectrometry. Furthermore, the determination of the minor and trace elements was carried out by instrumental neutron activation analysis (INAA) in both water and sediments samples, respectively. Pollution levels were also evaluated by calculating enrichment factors (EFs), contamination factors (CFs) and pollution load index (PLI). The data were discussed taking into account several parameters such as the distance from the pollution source, temperature, and location and showed that the environmental impact in this region could not be considered as negligible. The deviation of the isotopic ratio of U-234/U-238 from the equilibrium value indicated waters with intensive dissolution of uranium. The activity values in both waters and sediments found to be low in cool periods and increased in warm periods. Moreover, the concentrations of the elements U, Zn, and Fe were raised in water samples indicating possible pollution as well as the CFs and PLI denoted accumulation in the sediments and moderate to severe contamination for Zn and Cr in some cases.

Study of the radioactivity in environmental soil samples from Eastern Anatolia Region of Turkey

In this study, a detailed γ-ray spectrometer survey was performed to obtain the baseline data on natural and fallout radioactivity in soil samples (10–30 cm depth) collected from Iğdır which is a province in Eastern Anatolia Region of Turkey and located along the border with Armenia. Metsamor Nuclear Power Plant in Eastern Armenia is only about 20 km away from Iğdır province. The average activity concentrations of 226Ra, 232Th, 40K and 137Cs in the soil samples were found as 19.1±0.6 (range: 12.8–31.2 Bq kg−1), 21.9±0.6 (range: 11.6–36.8 Bq kg−1), 437.7±10.3 (range: 285.0–613.7 Bq kg−1) and 11.8±1.1 Bq kg−1, (range: 2.5–51.1 Bq kg−1), respectively. The radiological hazards caused by ionizing radiation emitted from these radionuclides on the population living in the region were assessed by estimating radiological parameters such as absorbed γ dose rate in outdoor and the corresponding annual effective dose rate from external exposure, annual effective dose rate from inhalation of radon and excess lifetime cancer risk. The results revealed that there is no significant radiological hazard for human population because the average values of radiological parameters are within the recommended limits.

Soil radioactivity levels, radiological maps and risk assessment for the state of Kuwait

An evaluation of the radioactivity levels associated with naturally occurring radioactive materials has been undertaken as part of a systematic study to provide a surface radiological map of the State of Kuwait. Soil samples from across Kuwait were collected, measured and analysed in the current work. These evaluations provided soil activity concentration levels for primordial radionuclides, specifically members of the (238)U and (232)Th decay chains and (40)K which. The (238)U and (232)Th chain radionuclides and (40)K activity concentration values ranged between 5.9 ↔ 32.3, 3.5 ↔ 27.3, and 74 ↔ 698 Bq/kg respectively. The evaluated average specific activity concentrations of (238)U, (232)Th and (40)K across all of the soil samples have mean values of 18, 15 and 385 Bq/kg respectively, all falling below the worldwide mean values of 35, 40 and 400 Bq/kg respectively. The radiological risk factors are associated with a mean of 33.16 ± 2.46 nG/h and 68.5 ± 5.09 Bq/kg for the external dose rate and Radium equivalent respectively. The measured annual dose rates for all samples gives rise to a mean value of 40.8 ± 3.0 μSv/y while the internal and internal hazard indices have been found to be 0.23 ± 0.02 and 0.19 ± 0.01 respectively.

Bioaccumulation of the artificial Cs-137 and the natural radionuclides Th-234, Ra-226, and K-40 in the fruit bodies of Basidiomycetes in Greece

The bioaccumulation of artificial Cs-137 and natural radionuclides Th-234, Ra-226, and K-40 by Basidiomycetes of several species is studied and evaluated in relation to their substratum soils. For this reason, 32 fungal samples, representing 30 species of Basidiomycetes, were collected along with their substratum soil samples, from six selected sampling areas in Greece. The fungal fruit bodies and the soil samples were properly treated and the activity concentrations of the studied radionuclides were measured by gamma spectroscopy. The measured radioactivity levels ranged as follows: Cs-137 from <0.1 to 87.2 ± 0.4 Bq kg(-1) fresh weight (F.W.), Th-234 from <0.5 ± 0.9 to 28.3 ± 25.5 Bq kg(-1) F.W., Ra-226 from <0.3 to 1.0 ± 0.5 Bq kg(-1) F.W., and K-40 from 56.4 ± 3.0 to 759.0 ± 28.3 Bq kg(-1) F.W. The analysis of the results supported that the bioaccumulation of the studied natural radionuclides and Cs-137 is dependent on the species and the functional group of the fungi. Fungi were found to accumulate Th-234 and not U-238. What is more, potential bioindicators for each radionuclide among the 32 species studied could be suggested for each habitat, based on their estimated concentration ratios (CRs). The calculation of the CRs' mean values for each radionuclide revealed a rank in decreasing order for all the species studied.

A preliminary evaluation of naturally occurring radioactivity concentration levels across the State of Kuwait

An evaluation of naturally occurring radioactive materials has been undertaken as part of a systematic study to provide a surface radiological map of the State of Kuwait. Soil samples were collected from twelve locations across Kuwait and analysed using high-resolution gamma-ray spectrometry. The (226)Ra and (235)U specific activity concentrations have been determined and used to estimate the (235)U/(238)U isotopic ratios which are found to be comparable to that expected for naturally occurring uranium material.

A century of oil and gas exploration in Albania: assessment of Naturally Occurring Radioactive Materials (NORMs)

The Naturally Occurring Radioactive Materials (NORMs) that are potentially generated from oil and gas extractions in Albania have been disposed of without regulations for many decades, and therefore, an extensive survey in one of the most productive regions (Vlora-Elbasan) was performed. A total of 52 gamma ray spectrometry measurements of soil, oil-sand, sludge, produced water and crude oil samples were performed. We discovered that relatively low activity concentrations of (226)Ra, (228)Ra, (228)Th and (40)K, with concentrations of 23±2Bq/kg, 23±2Bq/kg, 24±3Bq/kg and 549±12Bq/kg, respectively, came from the oil-sands produced by the hydrocarbon extraction of the molasses formations. The mineralogical characterizations and the (228)Ra/(40)K and (226)Ra/(40)K ratios of these Neogene deposits confirmed the predictions of the geological and geodynamic models of a dismantling of the Mesozoic source rocks. The average activity concentrations (±standard deviations) of the radium isotopes ((226)Ra and (228)Ra) and of the (228)Th and (40)K radionuclides in soil samples were 20±5Bq/kg, 25±10Bq/kg, 25±9Bq/kg and 326±83Bq/kg, respectively. Based on the measurements in this study, the future radiological assessments of other fields in the region should be strategically planned to focus on the oil-sands from the molasses sediments. Disequilibrium in the (228)Ra decay segment was not observed in the soil, sludge or oil-sand samples within the standard uncertainties. After a detailed radiological characterization of the four primary oil fields, we concluded that the outdoor absorbed dose rate never exceeded the worldwide population weighted average absorbed dose rate in outdoor air from terrestrial gamma radiation.

Environmental radionuclides in a coastal wetland of the Southern Laizhou Bay, China

The radioactivity concentration of (238)U, (232)Th, (226)Ra, (40)K, and (137)Cs in soil samples collected in a coastal wetland of the Southern Laizhou Bay, China were measured. Mean activity concentrations were 54.4±11.7, 57.9±9.7, 28.6±4.3, 542±21, and 10.2±2.9Bqkg(-1) dry weight for (238)U, (232)Th, (226)Ra, (40)K and (137)Cs, respectively. Statistical analyses suggested significant correlations between clay content and (40)K as well as (137)Cs. The radium equivalent activity, the absorbed dose rate in the air at 1m above the ground surface, and the external hazard index were calculated. The result showed that the radioactivity level in the wetland was in normal range. But sites along the river tended to have higher radiological hazard indexes. The vertical distributions of radionuclides in profiles illustrated some phenomena, such as vertical transport of (238)U, disequilibrium between (238)U and (226)Ra, and change in material sources.