Elevated Uranium Concentrations Research Articles

Uranium Speciation and Mobilization in Thawing Permafrost.

Uranium is a toxic and pervasive geogenic contaminant often associated with organic matter. Its abundance and speciation in organic-rich permafrost soils are unknown, thereby limiting our ability to assess risks associated with uranium mobilization during permafrost thaw. In this study, we assessed uranium speciation in permafrost soil and porewater liberated during thaw using active-layer and permafrost samples from a study area in Yukon, Canada where elevated uranium concentrations occur in bedrock and groundwater. Permafrost contained 1.1-28 wt % organic carbon and elevated uranium (range 7.6-1040 μg g-1, median 25 μg g-1) relative to local bedrock. The highest soil uranium concentrations were encountered in catchments hosting uranium-enriched bedrock and correlated positively with soil organic carbon. X-ray absorption spectroscopy, micro-X-ray fluorescence, and electron microscopy analyses revealed that solid-phase uranium predominantly occurs as uranium(VI) associated with soil organic matter. Extended X-ray absorption fine structure (EXAFS) analyses suggested the presence of uranium(VI) coordinated with carbon, consistent with bidentate-mononuclear uranyl complexation on carboxyl groups. Permafrost thaw produced circumneutral pH porewater (pH 6.2-7.5) with elevated dissolved uranium (0.5-203 μg L-1). Geochemical modeling indicated that calcium-uranyl-carbonate complexes dominated the dissolved uranium speciation. This study highlights that permafrost soil can mobilize uranium upon thaw and that uranium fate is linked to dynamic biogeochemical reactions involving organic carbon and groundwater chemistry.

Assessment of Radon and Naturally Occurring Radionuclides in the Vredefort Meteorite Crater in South Africa

The concentric impact rings of the Vredefort Crater contain rocks with elevated uranium concentrations resulting from the geological signature of a meteoric impact. The decay of this uranium was estimated to lead to elevated indoor radon concentrations in the Crater, but such a study has never been carried out. This study explores the relationship between the natural radionuclides found in the geology of the Vredefort Crater and indoor radon concentrations. This was achieved through soil sampling and radionuclide surveys conducted on three impact rings, supplemented by indoor radon measurements in dwellings found in the area. In situ measurements revealed that one impact ring had higher-than-average uranium concentrations at 50 Bq/kg. Surprisingly, the measured indoor radon levels were lower than expected (113 Bq/m3). These measurements were taken during the COVID-19 pandemic and colder months, conditions that would typically result in elevated indoor radon levels. Soil samples indicated uranium activity of 30 Bq/kg, comparable to the world average of 35 Bq/kg. However, defunct mine tunnels in the area exhibited elevated radon concentrations, averaging 364 Bq/m3. The disparity between expected and measured indoor radon levels was attributed to the composition of surficial deposits, bedrock, and architectural features of the dwellings preventing radon accumulation.

Different Dynamics of the Chemical Composition of Water in the Baikal Ecosystem (Baikal, Its Tributaries, and the Source of the Angara River)

Abstract —Multidirectional dynamics of changes in the chemical composition of the water of the only runoff of Lake Baikal, the Angara River, has been established. The cyclic-wave change in the interannual chemical composition of the Baikal water has been revealed, which indicates a long-term memory effect in the chemical time series of elements. Positive and negative temperature and chemical trends in the state of the water in the source of the Angara are observed, which are due to climate changes, the confinement of Baikal to the rift zone, and the composition of the enclosing rocks. It is shown that the current concentrations of monitored elements in the Angara source water depend also on their past concentrations but can change dramatically in the case of catastrophic environmental disturbances caused by natural and anthropogenic disasters (fires, drought, floods, earthquakes, etc.). The relationship between the elevated concentrations of uranium in the water and the seismic process in the Baikal area has been traced. The data obtained are based on the long-term (1950–2021) monitoring of the chemical composition of water in the Baikal ecosystem (Baikal, its tributaries, and Angara source).

Occurrence of Radionuclides and Hazardous Elements in the Transboundary River Basin Kyrgyzstan–Kazakhstan

Important for irrigation, the transboundary river basin between Kyrgyzstan and Kazakhstan is vulnerable to geochemical and anthropogenic sources of pollution. The use of water use indices, together with measurements of the elemental and radionuclide composition of the water and bottom sediments, provides a means for evaluating the continued use of the water from this region. Recent monitoring shows the highest concentrations of hazardous contaminants include lead and thorium contained in the bottom and banks of the Kichi-Kemin River. These contaminants are likely remnants of an accidental spill at the Aktyuz tailing dump in 1964. The specific activity of the Th-232 of the bottom and banks of the Kichi-Kemin River is 107–189 Bq/kg. There is evidence of anthropogenic sources of additional pollution from uranium in both the bottom sediments and the water in the Oyrandy River. The geochemical origins of uranium and other associated elements in the water of the Shu River are likely the Kamyshanovskoye deposit. Contact between the riverbed and ore bodies in this region likely leads to elevated concentrations of several geogenic contaminants, including lithium, strontium, uranium, and boron (Li, Sr, U, B), increasing by as much as 60–130%. The uranium concentrations in the water of channels that are used for irrigation exceed the maximum allowable contaminant levels by 3.8 times. Future work is needed to evaluate the ecological and human health impacts of these contaminants in irrigation and drinking water.

Elevated uranium concentration and low activity ratio (234U/238U) in the Œuf river as the result of groundwater–surface water interaction (Essonne river valley, South of Paris Basin, France)

Uranium (U) is a naturally occurring radioactive heavy metal widely distributed on Earth. Noticeable elevated U concentration and low activity ratio (AR) were occasionally detected in headwater stream of the Essonne river (Seine Basin, France), the namely Œuf river. This paper aims at providing new insight on geogenic U features in headwater streams and examines the role of river-groundwater interaction. The Œuf river was sampled four times in 2020 to investigate the influence of heterogeneous geology and hydrological seasonality. The dissolved fraction of water samples was analyzed for a variety of chemical parameters (anion, major, minor and trace element concentrations, isotopes 234U and 238U). The Œuf river was shown to exhibit elevated U concentration up to 19.3 μg L−1 (exceeding by 100-fold the value of 0.19 μg L−1 known for riverine average) and low AR down to 0.41 (almost the third of the value expected in surface water, i.e., 1.17). The Œuf river got enriched in U when receiving groundwater from Beauce Limestone Aquifer System. High U concentration (above 15 μg L−1) was found in association with low AR (below 0.5) in the stream water when flowing in the outcrop zone of one BLAS unit. Taking advantage of changes in the stream flow conditions and the geochemical contrast between surface and ground waters, mixing volumes were calculated. This study first examined the potential of using U isotopes in combination with selenium as hydrogeochemical tracers of the river-groundwater continuum. In HWS, the aquifer discharge was shown to supply 12 to 59 % of the river water. This study demonstrates the key role played by the river-groundwater interaction on river water chemistry in small streams draining catchment with various geology setting. It also supports the use of combining redox sensitive trace elements to track the river-groundwater continuum.

Assessing the Baseline Uranium in Groundwater around a Proposed Uraninite Mine and Identification of a Nearby New Reserve

The presence of uranium in groundwater is a cause of concern all over the world. In mineralized regions where elevated concentrations of uranium are possible in groundwater, mining activities can further degrade the water quality. Hence, it is essential to document the baseline uranium concentration in groundwater before the commencement of mining. This study was carried out with the objective of assessing the concentration of uranium in groundwater around a proposed uraninite mining site in the Gogi region, Karnataka, India. Gogi is a village in the Yadgir district of Karnataka where groundwater is the main source of water for domestic needs. The uranium mineralized zone in this region occurs along the major E-W trending Gogi-Kurlagere fault at a depth of about 150 m. Groundwater samples were collected every three months from January 2020 to October 2020 from 52 wells located in this area. The concentration of uranium in groundwater ranged from 1.5 ppb to 267 ppb. The USEPA and WHO have recommended a permissible limit of 30 ppb, while the Atomic Energy Regulatory Board of India has a limit of 60 ppb for the purpose of drinking water. Based on these permissible limits for uranium in drinking water, concentrations exceeded the limit in about 25% of wells within 20 km from the mineralized region. Wells present in the granitic and limestone terrain exhibited higher concentrations of uranium in this area. Uranium concentration in groundwater changes depending on the degree of weathering, lithology, and rainfall recharge. This study will serve as a baseline and will help to assess the impact of mining activities in this region in the future. In wells where the uranium concentration exceeds permissible limits, it is suggested not to use groundwater directly for drinking purposes. These sites need to be explored further for the possible presence of uranium-bearing minerals.

Radioactive (U, Th) elements in technogenic waters of tungsten deposits in Eastern Transbaikalia (Russia)

The peculiarities of distribution and migration of uranium and thorium in technogenic waters of seven tungsten deposits located in Eastern Transbaikalia have been studied. It has been established that elevated concentrations of uranium are found in all types of investigated waters, whereas the accumulation of thorium was recorded only in acidic waters (pH < 4). Maximum concentrations of elements were found in the areas of deposits localized in leucocratic and lithium-fluorine granitoids. In acidic waters, uranium and thorium migrate primarily in the form of sulfate and fluoride complex ions, while in neutral and weakly alkaline conditions, carbonate complexes come to the fore.

Distribution and temporal variability of uranium and toxic metal(loid)s in snow and rainwater from an oil industry and urban area in Thessaloniki-Greece.

The concentrations of uranium and nine elements (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in snow and rainwater samples were determined. Samples were collected in Thessaloniki-northern Greece in three sites, one in the industrial area close to an oil production power plant and two in the centre of the city. Snow samples were collected during January-February 2019 and 2021 whereas in the case of rainwater, a two-year survey has been performed during 2019 and 2020. The activity concentrations of the uranium radioisotopes were measured by alpha spectrometry whereas the metal(loid)s concentrations were determined by inductively coupled plasma mass spectroscopy (ICP-MS). The elevated concentrations of uranium (U) and the deviation of the isotopic ratio of U-234/U-238 from the equilibrium value indicated intensive dissolution of uranium. The results were analyzed using statistical analysis (Shapiro-Wilk, Friedman and Kruskal-Wallis tests). The obtained data and the calculated enrichment factors (Efs) denote variation of the concentration values between industrial and urban area and different elemental distribution influenced from anthropogenic contributions, meteorological conditions and the COVID-19 pandemic.

Evaluation of uranium concentration in the blood breast cancer women with CR-39 detector

Some governorates of Iraq are considered as uranium-contaminated areas. The spread of cancerous tumors injuries was recorded in different parts of Iraq at very high rates. As cancer is closely related to high level of uranium in the blood, this study was conducted on women with breast cancer to evaluate the uranium concentrations in their blood. The aim of the study is to assess the concentration of uranium in the blood Iraqi breast cancer women to establish reference values for the levels of toxic uranium in their blood and the possibility of getting breast cancer. A total of 39 blood samples were collected from breast cancer women and a control group. CR-39 track detector has been used to evaluate the uranium concentration in blood samples by placing a drop of blood on the detectors and calculating the uranium concentrations by irradiating the detectors with a neutron source. Statistical analysis is achieved utilizing SPSS programme. The outcomes show elevated levels of uranium concentration in the blood of women with breast cancer, which was found to be 92±0.6 ngL−1 compared to the control group (40 ±0.4 ngL−1), and internationally published data. The results show that the uranium concentration in the blood of breast cancer women is higher than those in the control group and some of the globally published data. This indicated that there is a relationship between the elevated concentrations of uranium in blood and the risk of getting breast cancer.

Origin of Elevated Uranium Concentration and Low Activity Ratio (234u/238u) in a Headwater Stream of the Essonne River (South of Paris Basin, France)

Origin of Elevated Uranium Concentration and Low Activity Ratio (234u/238u) in a Headwater Stream of the Essonne River (South of Paris Basin, France)

Maternal metal concentration during gestation and pediatric morbidity in children: an exploratory analysis

BackgroundThe majority of studies linking exposure to metals with certain health outcomes focus on known toxic metals. Alternatively, this study assesses the extent to which exposure to a wider range of metals during gestation is associated with childhood morbidity.MethodsWe analyzed the concentrations of 25 metals found in urine samples of 111 pregnant women of Arab-Bedouin origin collected prior to birth. In addition, we collected medical records on their offspring for six years following birth, including every interaction with HMOs, local hospitals, and pharmacies.ResultsThe main types of morbidities diagnosed and treated during this period were preterm births, malformations, asthma-like morbidity, cardiovascular and behavioral problems, and obesity. Multivariable analysis showed that offspring born before term were more likely to have been exposed to elevated maternal concentrations of zinc, thallium, aluminum, manganese, and uranium, all with adjusted relative risk above 1.40 for an increase by each quintile. Likewise, children with asthma had been exposed to higher levels of magnesium, strontium, and barium at gestation, while behavioral outcomes were associated with elevated biometals, i.e., sodium, magnesium, calcium, selenium, and zinc, as well as higher levels of lithium, cobalt, nickel, strontium, cadmium, vanadium, arsenic, and molybdenum. A heatmap of adjusted relative risk estimates indicates the considerable implications that exposure to metals may have for preterm birth and developmental outcomes.ConclusionsThe current study shows that perinatal exposure to metals is adversely associated with pediatric morbidity. Further such analyses on additional samples are warranted.

Unconventional uranium in China's phosphate rock: Review and outlook

Some phosphate rock contains elevated concentrations of natural uranium. China is the largest phosphate rock producing country in the world and will soon have the largest uranium requirements in the world as well. Most phosphate rock deposits in China show low uranium concentrations (20–30 mg/kg) so that the recovery of radiotoxic heavy metals is neither economically appropriate nor ecologically necessary. China does, however, also have elevated uranium concentrations (≥90 mg/kg) in phosphate rock deposits in Sichuan and Yunnan. We estimate that China could have recovered nearly 648 metric tU (1.43 million lb U3O8) from those mines in 2016. The amount corresponds to 9.7% of the total reported uranium requirements in this year or 39.3% of reported domestic uranium production in 2016. The future uranium recovery potential may be even higher in total numbers (1158 tU or 3.01 million lb U3O8 in 2030). The main reason are potentially increasing imports of phosphate rock from large exporting countries such as Morocco that show higher average uranium content. In addition, medium- to lower-grade domestic phosphate rock resources with larger shares of accompanying heavy metals, that include rare earths and uranium, will have to be processed. Although the uranium supply for China is currently not at risk, the supply security could be further increased by obtaining unconventional uranium from domestic and imported phosphate rock.

Ultrafast high-capacity capture and release of uranium by a light-switchable nanotextured surface.

Nuclear power is growing in demand as a promising sustainable energy source, its most prevalent source being uranium salts. The resulting processing and transportation of uranium raise concerns regarding the environmental impact and risks for human health. Close proximity to uranium mines puts populations at higher risk for exposure due to elevated uranium concentrations. As the main form of uranium in aqueous solutions, uranyl (UO22+) has been the focus of many methods of uranium sieving; most fall short by being time-consuming or lacking a retrieval mechanism for the captured uranium. Here, we demonstrate the ultrafast and selective uranyl-capturing properties of aptamer-modified branched silicon nanopillar (BSiNP) arrays. Our nanostructured surfaces demonstrate an ultrahigh surface area modified with a uranyl-specific DNA aptamer, allowing for high uranyl-capturing capacity, reaching up to 550 mg g−1. Uranyl capture is followed by the activation of a covalently bonded photoacid, causing a light-triggerable, ultrafast release. This capture-and-release cycle results in the collection of over 70% of the uranium found in the original samples within less than one hour.

Predictive modeling for U and Th concentrations in mineral and thermal waters, Serbia

The objective of this paper was to determine background values (BV) and anomalous values (AV) of U and Th in groundwater and to establish hydrogeochemical conditions which lead to the elevated concentrations of these elements in groundwater. The methodology included planning and collecting of water samples, laboratory work, and assessment of BV and AV concentrations in accordance with the dataset distribution, based on consideration of hydrogeochemical conditions in the hydrogeological system. Groundwater sampling included 144 occurrences of mineral and thermal water from Serbian territory, belonging to different hydrogeological systems. Field parameters were measured for temperature (T), pH, electrical conductivity (EC), oxidation–reduction potential (ORP), dissolved oxygen (DO), and carbon dioxide (CO2). Standard laboratory measurements were applied for the determination of major chemical components (Ca, Mg, Na, K, Cl, HCO3, and SO4) and U and Th concentrations were measured by ICP-MS. The first step for obtaining U and Th threshold values was based on non-parametric statistical analysis on the data sets. Further analysis of threshold values enabled establishing hydrogeochemical conditions influencing elevated concentrations of U and Th and setting up the logistic regression (LR) model. Differences in the hydrochemical properties of U and Th can be observed based on predictor variables from LR models. Physico-chemical parameters Eh and pH, groundwater type, and geochemical environment (cretaceous igneous rocks) were significant predictors for elevated uranium concentrations, while significant predictors in the thorium LR model were the pH value, the concentration of SO4 in the solution, and the water-bearing rocks (tertiary igneous rocks).

Behavior of uranium series in groundwater of the Wajid Formation, Wadi AdDawasir, Saudi Arabia.

The inventories and the possible mechanisms behind the relative deficiency of both radium and uranium release processes within an elevated gamma-anomalous rock were investigated. A field survey was performed on the highest radioactive anomalous zone that was recorded at Jabal Al Alam (20° 13' 10.06″ N and 44° 14' 32.13″), with the ferruginous sandstone, iron oxide band, and iron concretions (with uranium content and reaching up to1500 ppm). The chemical analyses and the laboratory's gamma-ray spectrometric measurements demonstrated high uranium levels in the analyzed rock samples of the Wajid Sandstone (up to 1000 ppm). The borehole geophysical logs further confirmed that the radioactive anomalies are attributed to the sandstone sequence of the Wajid Formation that is often found associated with elevated concentrations of uranium. The groundwater samples taken from the wells tapping the Wajid aquifer showed uranium concentrations ranging from 0.01 to 5.5 ppb (μg/L). The average 226Ra in groundwater samples was 0.2 Bq L-1. The majority of the 226Ra and 228Ra activities were below the lower limit of detection (LLD). The radiochemical analyses of water samples from the Wajid aquifer display low concentrations of both uranium and 226Ra, with relation to uranium content in host rocks. This was attributed to the fact that uranium is susceptible to form iron oxide complexes, causing them to precipitate in a more stable form. Furthermore, iron oxides coat the sand grains of the Wajid Formation and accordingly might act as a foundation for re-adsorption for both uranium and radium, resulting in their relative deficiency in the surrounding water. The coating might also act as a physical barrier resulting in hindrance of the recoil nuclei due to its significant thickness (several orders of magnitude) compared with that of the average (120 nm) whole alpha-recoil track (ART). The coating layer thickness was determined via scanning electron microscopy (SEM) and was found to be up to 180 μm.

Uranium exposure of the Swiss population based on 24-hour urinary excretion.

Important regional differences in uranium exposure exist because of varying uranium concentrations in soil, water and food. Comprehensive data on the exposure of the general population to uranium is, however, scarce. Based on the 24-hour urinary excretion, the uranium exposure of the adult Swiss population was assessed in relation to age, sex, place of residence, body mass index (BMI), smoking habit and type of drinking water, as well as risk factors in relation to kidney impairment and indicators of a possible renal dysfunction. Uranium was quantified in 24-hour urine from a nationwide population-based sample (n = 1393). The ratio 238U/233U was measured for isotope dilution calibration with a sector field inductively coupled plasma mass spectrometer (HR-ICP-MS). Overall median and 95th percentile were 15 and 67 ng/24 h, respectively. The place of residence significantly influenced urinary uranium excretion. However, most of the highest urinary uranium excretion levels could not be associated to areas known for their elevated uranium concentrations in the drinking water. Sources other than the local drinking water (e.g., bottled water) might be important, too. Gender as well as albumin excretion also had a significant effect on uranium excretion. The latter was, however, strongly dependent on the presence of diabetes mellitus. No association was found for age, BMI, smoking habit or the other examined kidney related variables. On the basis of uranium exposure, assessed via 24-hour urinary uranium excretion, and current knowledge of the toxicity of naturally occurring uranium, a substantial corresponding health risk for the general adult population is unlikely. However, as long as no specific sensitive biomarker for the biological impact of low-dose chronic uranium exposure has been identified and validated, assessing subtle health impact of such exposure will remain difficult.

Uranium enrichment in the Lala Cu-Fe deposit, Kangdian region, China: A new case of uranium mineralization associated with an IOCG system

Elevated uranium concentrations have been reported in many IOCG deposits, but detailed information about the occurrences of uranium minerals and their relationships with other minerals remains scarce, which hinders understanding of the mineralization mechanisms and the nature of the association of these metals. This paper reports a new case of uranium enrichment in an IOCG system, the Lala Cu-Fe deposit in the Kangdian region, SW China. Whole-rock analyses of ores and barren rocks yielded highly variable U concentrations ranging from 0.76 to 266 ppm. Uranium shows a strong positive correlation with Mo, broadly positive correlations with Cu and ΣREE, and a vague, negative correlation with Th. Four uranium minerals, uraninite [UO2], uranothorite [(Th,U)SiO4], polycrase [(Y,Ca,Ce,U,Th)(Ti,Nb,Ta)2O6], and coffinite [U(SiO4)1-x(OH)4x], were identified. The uraninite is divided into two phases: phase 1 (Ur1) characterized by corroded or irregular crystal shapes, and phase 2 (Ur2) showing well-developed, subhedral to euhedral crystal shapes. Ur1 is interpreted to be formed in the primary Cu – Fe – Mo – REE – U mineralization, together with the bulk of Cu and other metal sulfides, as well as other U and REE minerals, including uranothorite, polycrase, bastnäsite and xenotime, and accompanied by K-alteration (K-feldspar and biotite). Ur2 is interpreted to be formed in a secondary hydrothermal event characterized by introduction of fluorite and carbonates, in which U and Mo, and to lesser extent Cu and REE, were remobilized, while Th remained relatively stable. The primary mineralization is inferred to have taken place in a period from ca. 1086 to 1053 Ma based on previous Re-Os geochronology, and the secondary mineralization (remobilization) likely took place from ca. 888 to 828 Ma, as suggested by uraninite chemical ages obtained in this study and other published geochronological data. These ages correspond to tectonomagmatic events taking place in generally extensional environments, in the western margin of the Yangtze Block during the Meso- to Neoproterozoic time. The Lala Cu-Fe deposit represents a new case of IOCG deposits with U (and REE) enrichment, the economic potential of which warrants further examination.

Application of dissolved gases concentration measurements, hydrochemical and isotopic data to determine the circulation conditions and age of groundwater in the Central Sudetes Mts

In the Central Sudetes, the areas of sedimentary Permian and Carboniferous rocks are characterized by small resources of groundwater and are much less understood than aquifer systems occurring in the crystalline and Mesozoic sedimentary rocks. The environmental tracer studies conducted in a double sampling cycle during changing conditions of groundwater inflow can significantly facilitate the understanding of hydrogeological conditions in areas of the complicated geological structure. Therefore, in order to identify the hydrogeological conditions of study area, measurements of geogenic and anthropogenic gases (He, Ne, Ar, CFC-11, CFC-12 and SF6), determinations of isotopic composition of groundwater (δ18O, δ2H and 3H) and the hydrogeochemical data (including selected REEs, thorium and uranium) were used. The research, which was conducted both in natural groundwater flow conditions and in conditions of flow disturbed by the continuous exploitation of the groundwater, enabled, among other things, a direct determination of the rate of maximum decomposition of CFC-11 and CFC-12 at depths of 50–450 m in the clastic rocks. It ranges from 189 to 315·10−12 g·L−1·yr−1 for CFC-11 and from 110 to 198·10−12 g·L−1·yr−1 for CFC-12. The research conducted also indicates that in the study area the vertical or nearly vertical groundwater flow may have significance comparable to the lateral groundwater flow. This results in an intense mixing of groundwater which leads to the local occurrence of groundwater containing the ions and gases in concentrations characteristic of the deep aquifers in the studied area, with the simultaneous occurrence of ions and gases of anthropogenic origin. The results of measurements on CFCs, SF6 and noble gases indicate a significant inflow of young groundwater to the whole freshwater zone. An occurrence of a geogenic SF6 source, which is most probably associated with volcanic rocks, was also found. Calculated the groundwater ages indicate that the research area is dominated by groundwater of age less than 1 ka, and mainly in the range of 0.05–0.25 ka. The results of modeling of the influence of the variability of U and Th concentrations on the He in situ production within the aquifer (PHe) indicate, that for groundwater with He concentrations of 10−6–10−8 cm3 STP g−1, i.e. modern groundwater, the He in situ production within the aquifer is actually negligible, so it may be omitted in the calculation of their age. Considering the fact that, in the study area which is terrain with elevated uranium concentration there is no significant effect of PHe on groundwater dating using the helium method, it can be concluded that the dating results obtained with this method in such areas can be fully comparable with those obtained for areas with lower concentrations of uranium. It was also found that mobile ions of uranium and suspension of thorium compounds occurred in the groundwater are not a significant source of He in situ production within the studied aquifers.

Measurement of radioxenon and radioargon in air from soil with elevated uranium concentration

Among the most important indicators for an underground nuclear explosion are the radioactive xenon isotopes 131mXe, 133Xe, 133mXe and 135Xe and the radioactive argon isotope 37Ar. In order to evaluate a detection of these nuclides in the context of a nuclear test verification regime it is crucial to have knowledge about expected background concentrations. Sub soil gas sampling was carried out on the oil shale ash waste pile in Kvarntorp, Sweden, a location with known elevated uranium content where 133Xe and 37Ar were detected in concentrations up to 120 mBq/m3 and 40 mBq/m3 respectively. These data provides one of the first times when xenon and argon were both detected in the same sub soil gas. This, and the correlations between the radionuclides, the sub soil gas contents (i.e. CO2, O2, and radon) and uranium concentration in the pile, provide very interesting information regarding the natural background and the xenon concentration levels and can most likely be used as an upper limit on what to be expected naturally occurring.

Using spatial statistics to identify the uranium hotspot in groundwater in the mid-eastern Gangetic plain, India

The occurrence of uranium in groundwater is of particular interest due to its toxicological and radiological properties. It has been considered as a relevant contaminant for drinking water even at a low concentration. Uranium is a ubiquitously occurring radionuclide in the environment. Four hundred and fifty-six (456) groundwater samples from different locations of five districts of South Bihar (SB) were collected and concentrations of uranium (U) were analyzed using a light-emitting diode (LED) fluorimetric technique. Uranium concentrations in groundwater samples varied from 0.1 µg l−1 to 238.2 µg l−1 with an average value of 12.3 µg l−1 in five districts of Bihar in the mid-eastern Gangetic plain. This study used hot spot spatial statistics to identify the distribution of elevated uranium concentration in groundwater. The hypothesis whether spatial distribution of high value and low value of U is more likely spatially clustered due to random process near a uranium hotspot in groundwater was tested based on z score and Getis-Ord Gi* statistics. The method implemented in this study, can be utilized in the field of risk assessment and decision making to locate potential areas of contamination.