High Uranium Content Research Articles

Anthropogenic and geologic causes of anomalously high uranium concentrations in groundwater used for drinking water supply in the southeastern San Joaquin Valley, CA

Concentrations of uranium (U) >30 µg/L in groundwater are relatively uncommon in drinking water in the United States but can be of concern in those areas where complex interactions of aquifer materials and anthropogenic alterations of the natural flow regime mobilize U. High concentrations (>30 µg/L) of U in the southeastern San Joaquin Valley, California, USA, have been detected in 24 percent of 257 domestic, irrigation, and public-supply wells sampled across an approximately 110,000 km2 area. In this study we evaluated mechanisms for mobilization of U in the San Joaquin Valley proposed in previous studies, confirming mobilization by HCO3 and refuting mobilization by NO3 and we refined our understanding of the geologic sources of U to the scale of individual alluvial fans. The location of high concentrations depends on the interactions of geological U sources from fluvial fans that originate in the Sierra Nevada to the east and seepage of irrigation water that contains high concentrations of HCO3 that leaches U from the sediments. In addition, interactions with PO4 from fertilized irrigated fields may sequester U in the aquifer. Principal component analysis of the data demonstrates that HCO3 and ions associated with high total dissolved solids in the aquifer and the percentage of agriculture near the well sampled are associated with high U concentrations. Nitrate concentrations do not appear to control release of U to the aquifer. Age dating of the groundwater and generally increasing U concentrations of the past 25 years in resampled wells where irrigation is prevalent suggests that high U concentrations are associated with younger water, indicating that irrigation of fields over the past 100 years has significantly contributed to increasing concentrations and mobilizing U. In some places, the groundwater is supersaturated with uranyl-containing minerals, as would be expected in roll front deposits. In general, the interaction of natural geological sources high in U, the anthropogenically driven addition of HCO3 and possibly phosphate fertilizer, control the location and concentration of U in each individual fluvial fan, but the addition of nitrate in fertilizer does not appear control the location of high U. These geochemical interactions are complex but can be used to determine controls on anomalously high U in alluvial aquifers.

Estimation of radon potential through measurement of uranium concentrations in granite geology

The geology of an area can be used as a predictor for radon potential. Granite rock typically contains a high concentration of uranium and subsequent elevated emanation of radon gas. The geology of the western part of the Western Cape Province in South Africa is dominated by granite bedrock but very few studies on radon have been conducted in this area. Uranium concentrations were consequently measured on a large granite hill in the Saldanha Bay area of the Western Cape and a relationship between indoor radon and uranium concentrations was used to model radon potential on the outcrop. Results from granite rich environments in India were modelled in order to extract a relationship between indoor radon concentrations, radon exhalation rates and uranium concentrations. Radon exhalation rates greater than 0.35 Bq/m2h were predicted and estimated indoor radon concentrations in excess of 400 Bq/m3 were also predicted for the hill. The modelled results were compared with indoor radon measurements taken in the town of Paarl in the Western Cape, which sits on the same granite bedrock formation. The predicted radon potential correlated well with the physical measurements.
 Significance:
 
 Extensive in-situ uranium measurements were conducted by utilising a self-developed gamma-ray detection instrument (the GISPI) by means of a unique method.

Bacterial community analysis of sulfate-reducing granular sludge exposed to high concentrations of uranium

Abstract Sulfate-reducing granular sludge was used for uranium-contaminated wastewater treatment and the responsible microbial community was analyzed. Four feedings, with 6 days for every feeding and 20 mg/L initial uranium, were provided at 27.5 (±2.5) °C. After the four feedings, a uranium removal efficiency of 94% was obtained. Environmental scanning electron microscopy (ESEM) showed that short rod bacteria were the dominant microorganisms in the granular sludge. X-ray energy dispersive spectroscopy (EDS) confirmed the presence of uranium on the granular surface. High-throughput sequencing was carried out for analyzing the bacterial diversity and community structure. The total data set comprised 8,290 high quality sequences, which could be divided into 605 operational taxonomic units (OTUs). The library coverage was 0.96 and the alpha diversity indices of ACE, Chao1, Shannon and Simpson were 2,255.40, 1,346.12, 4.03 and 0.05, respectively. There were 13 bacterial genera present with a ratio of more than 1% of the total 124 genera, among which Desulfovibrio (16.48%), Clostridium IV (9.29%), Bacteroides (3.46%) and Citrobacter (1.41%) were assumed as the functional bacteria, with a cumulative proportion of 30.64% of the total bacterial population. The results provide insights into the bacterial community of sulfate-reducing granular sludge exposed to high concentrations of uranium (20 mg/L).

Flow period influence on uranium and trace elements release in water from the waste rock pile of the former La Commanderie uranium mine (France)

Uranium mining activities expose uranium ore and mine tailings to the surface environment, where the release of radionuclides is facilitated by weathering at rates exceeding those typically found in nature. Therefore, close to former uranium mining sites, radionuclides and especially uranium concentrations in water may surpass local background levels. The methodology proposed herein, entails coupling, gamma-ray mapping, water sampling and chemical analyses including DGT (Diffusive Gradient in Thin Film) measurements, provides new insights into describing the environment of the La Commanderie site (France). Gamma-ray mapping allows identifying water seepage, output from a waste rock pile, as a potential pathway for radionuclides into the environment. Water seepage monitoring has shown: a low pH value (4.2), high sulfate content (179 mg.L−1) and high uranium concentrations of up to 436 μg.L−1. These recordings indicate that an acid mining drainage (AMD) process is occurring inside or under the oxidized parts of the waste rock pile. Monitoring data over three flow periods revealed the release of the highest uranium concentrations during a high-flow period downstream of the site, which is compliant with local regulations. The AMD process is also responsible for the release of significant amounts of Fe, Mn and As within the immediate environment in both dissolved and particulate forms. Changes in dissolved oxygen concentration and redox potential during low flow periods, modify the speciation of Fe (in AMD waters) which acts as a scavenger for other elements such as As, Mn and U. The use of DGT under environmental conditions, and specifically AMD waters, seems to be relevant in comparison to filtered spot water sampling strategies. Moreover, based on DGT measurements, the dissolved part of the released uranium is considered as labile with concentrations above the environmental standards for freshwater organisms.

Differentiating anthropogenic and natural sources of uranium by geochemical fingerprinting of groundwater at the Homestake uranium mill, Milan, New Mexico, USA

A multiparameter geochemical-isotopic fingerprinting approach was used to differentiate anthropogenic and natural signatures of uranium contamination near the Homestake uranium mill site (Site), near Milan, New Mexico, USA. The Site consists of two tailings piles from milling operations and groundwater contamination from these tailings has been noted. The Site lies within the lower San Mateo Creek Basin and has multiple regional sources of uranium contamination from mining and mill operations. The Site is underlain by a heterogeneous alluvial aquifer, which is in turn underlain by basement rock of the Chinle Group aquifer and the underlying San Andres-Glorieta Formation aquifer. To help decipher signatures, several statistical approaches were used including principal component analysis, non-metric multidimensional scaling, and cluster analysis. Piper diagrams indicate two end-member water types at the Site, sulfate–Na–K generally in the Chinle Group aquifer and sulfate–Ca generally in the alluvial aquifer. There are wells from both aquifers that plot between the two end members. Uranium concentrations from the Site fall into three broad categories: less than the drinking water standard of 30 µg/L (n = 3), from 30 to 100 µg/L (n = 9), and greater than 100 µg/L (n = 8). Component loadings in a principal component analysis are highest for uranium isotopes, uranium, molybdenum, chloride, sodium, 228radium, and gross alpha–beta, which affect the similarities or differences among wells sampled. Results suggest that several alluvial wells north of the Site have groundwater with anthropogenic fingerprints from regional sources related to upgradient mining. Well water with higher uranium concentrations has uranium activity ratios close to 1, which is indicative of mining or milling signatures. These same wells have elevated radon activities. This information can be used to inform Site managers regarding the source of water related to uranium at the Site and provide an approach for geochemical fingerprinting.

Geochemical Behavior of Uranium and Radon in Groundwater of Jurassic Granite Area, Icheon, Middle Korea

Uranium concentrations (a total of 82 samples) in groundwater in Icheon, middle Korea, showed a wide range from 0.02 to 1640 μg/L with a mean of 56.77 μg/L, a median of 3.03 μg/L, and a standard deviation of 228.63 μg/L. Most groundwater samples had quite low concentrations: 32.9% were below 1 μg/L, while 15.9% exceeded 30 μg/L, the maximum contaminant level (MCL) of the US EPA (Environmental Protection Agency). Radon concentrations also ranged widely from 1.48 to 865.8 Bq/L. Although the standard deviation of radon was large (151.8 Bq/L), the mean was 211.29 Bq/L and the median was 176.86 Bq/L. Overall, 64.6% of the samples exceeded the alternative maximum contaminant level (AMCL) of the US EPA (148 Bq/L). According to statistical analyses, there was no close correlations between uranium and radon, but there were correlations between uranium and redox potential (Eh) (−0.54), dissolved oxygen (DO) (−0.50), HCO3− (0.45), Sr (0.65), and SiO2 (−0.44). Radon showed independent behavior with respect to most components in groundwater. Uranium concentrations in groundwater increased with increasing water–rock interactions. Anomalously high uranium and radon concentrations in groundwater are preferentially localized in granite areas and spatial distributions are remarkably heterogeneous.

First direct evidence for a contiguous Gondwana shelf to the south of the Rheic Ocean

Abstract Sea-level rise after the Hirnantian glaciation resulted in the global inundation of continental shelf areas and the widespread formation of early Silurian black shales. Black shales that were deposited on shelves receiving drainage from earlier glaciated areas have high uranium (U) contents because large-scale glacial erosion brought rocks with leachable U to the surface. In contrast, black shales receiving drainage from non-glaciated areas that had lost leachable U earlier have low U contents. Early Silurian U-rich shales formed only on shelf areas that had not been separated from earlier-glaciated mainland Gondwana by oceanic lithosphere. Therefore, early Silurian U-rich black shales within the Variscan orogen provide direct evidence that these areas had not been separated from mainland Gondwana, but were part of the same, contiguous shelf. This implies that the Rheic Ocean was the only pre-Silurian ocean that opened during the early Paleozoic extension of the peri-Gondwana shelf.

Timing and structure of the weak Asian Monsoon event about 73,000 years ago

Abstract Oxygen isotope (δ18O) records of cave speleothem have played an important role in the past two decades in characterizing the Asian Monsoon (AM) variability and correlating the monsoonal events with other global climate events on millennial timescales. Of a series of millennial events occurred during the last glacial period, the Chinese Stadial-20 (CS-20, corresponding to the Greenland Stadial-20, GS-20) event around ∼73 kyr BP (thousand years before present, where present = 1950 AD) is distinctive, since it is the weakest AM event during the last glacial period and is likely linked to the Toba volcanic super-eruption. While Greenland ice core records are commonly used to correlate the last glacial millennial events, yet their absolute age uncertainties around the GS-20 is larger than 1000 years. This prohibits precise correlations of the event between global climate archives from different climate systems to investigate the underlying climatic dynamics. Here, we present three Chinese cave stalagmite δ18O records from the AM region, covering a period from 76 to 71 kyr BP, across the CS-20. All stalagmites have high uranium contents and relatively fast growth rates, allowing acquisition of high-resolution (∼10 years) δ18O records with precise 230Th age controls (≤200 years, 2σ) to precisely characterize the structure and timing of the CS-20. Our results demonstrate that the onset and termination of the CS-20 are more gradual in Chinese cave records relative to the GS-20 event in Greenland ice core records. As such, we suggest a new ‘break-point’ approach to correlate CS-20 with GS-20, at either the initial onset or initial termination shifts of the events, instead of the conventional ‘mid-point’ match. We dated the initial onset and initial termination of CS-20 to ~74.0 ± 0.2 and 72.5 ± 0.2 kyr BP, respectively, confirming the Greenland ice core chronology well within the quoted uncertainty. The ‘break-point’ correlation at the GS-20/CS-20 initial termination suggests a lagged onset of CS-20 relative to the onset of GS-20. The lagged onset is in line with a northern high-latitude forcing mechanism triggering the event and a central role of oceanic reorganizations in the propagation of the climate signal. An alternative ‘break-point’ correlation at the GS-20/CS-20 initial onset suggests that the CS-20 initial termination leads the GS-20 initial termination by a few hundred years. This apparent paradox thus calls for further empirical and theoretical studies to better understand the underlying climatic dynamics and in turn the correlation strategy.

U–Pb dating of single-grain uraninite by isotope dilution thermal ionization mass spectrometry

Uraninite can be used to measure U–Pb ages due to its high uranium and low common lead content. Accurate in-situ U–Pb dating of uraninite by secondary ion mass spectrometry (SIMS) or laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) requires a matrix-matched external standard as a result of the different Pb/U fractionation behavior in varied matrices. However, being lack of the suitable uraninite standard, in-situ U–Pb dating technique of uraninite is hardly carried out in many laboratories. In this paper, a method with a detailed analytical procedure is proposed for U–Pb age determination of single-grain uraninite by isotope dilution thermal ionization mass spectrometry (ID-TIMS). This method not only avoids the difficulty of looking for the ideal uranium mineral standards because of no need to make matrix effect calibration, but also gives high precision ages with a small amount of sample used (<1 μg), which provides a basis for in-situ ID-TIMS U-Pb dating of uraninite on the rocks or thin sections.

Assessment of Individual Radiosensitivity in Inhabitants of Takandeang Village － A High Background Radiation Area in Indonesia

People living in high background radiation area (HBRA) possibly developed the radioadaptive response (RAR) phenomena. Mamuju area in West Sulawesi Indonesia also known as the HBRA in Indonesia due to high natural uranium contents. It is possible that RAR was developed in Mamuju inhabitants. To prove this hypothesis, here in this study evaluation of the individual radiosensitivity in Takandeang Village, Mamuju inhabitants using G 2 micronucleus (MN) assay was conducted. Association between blood groups and TP53 Arg72Pro polymorphism with individual radiosensitivity also evaluated in this study. Using G 2 MN assay we assessed the individual radiosensitivity of Takandeang Village inhabitants and control samples. For each sample, three parameters were calculated. The spontaneous (baseline) MN number, MN number after 0.5 Gy in vitro irradiation and radiation induced MN were calculated to predict the individual radiosensitivity. The radiation induced MN was defined by subtracting the spontaneous MN number from the MN number after irradiation. The mean and SD of the number of micronucleus induced by radiation found in control group (CG) was set as the cut-off value to determine the individual radiosensitivity in all samples. The radiation induced MN higher than the mean CG + 1SD CS was scored as 1, indicating a milder radiosensitive phenotype, whereas a result higher than the mean CG + 2SD CG was scored as 2, and indicated a more severe radiosensitive phenotype. When the individual value was lower than the mean CG + 1SD CG, a score of 0 was attributed to the tested subject. Results showed that four individuals in Takandeang Village inhabitants were having a milder radiosensitive phenotype, whilst the other was categorized as normal radiosensitive. The similar finding also found in control samples. Our study failed to find a correlation between radiosensitivity and blood group also the TP53 Arg72Pro polymorphism. Overall our study revealed the possibility of RAR phenomena in Takandeang Village inhabitants. Further investigation using a different point of radiation dose value and larger sample number should be performed to validate this study results.

ГЕОХИМИЯ УРАНА И ТОРИЯ В ДОННЫХ ОТЛОЖЕНИЯХ МАЛЫХ ИСКУССТВЕННЫХ ВОДОЕМОВ И ОЗЕР НА ТЕРРИТОРИИ ЮГА ТОМСКОЙ ОБЛАСТИ

Актуальность. Радиоактивные элементы являются эффективными маркерами состояния донных отложений малых водоемов и озер. Актуальность проблемы определяется слабой изученностью радиоактивных элементов в донных осадках озер и искусственных водоемов на территории юга Томской области. Цель: изучение радиогеохимических особенностей донных осадков озер и искусственных водоемов на территории юга Томской области. Объектом исследования являются донные отложения малых водоемов и озер юга Томской области. Методы: детальное опробование донных отложений малых водоемов, многоэлементный инструментальный нейтронно-активационный анализ, обработка и интерпретация полученных данных методами прикладной статистики. Результаты. Проведены радиогеохимические исследования донных осадков озер и искусственных водоемов на территории юга Томской области. Сделаны оценки среднего содержания урана и тория в донных осадках озер и искусственных водоемов на территории юга Томской области. В процессе исследований установлено, что содержание как урана, так и тория зависит от минерального типа донных осадков. Наименьшие концентрации урана были установлены в торфянистом типе, а наиболее высокие концентрации – в терригенном типе донных осадков. Установлено две зоны с повышенным содержанием урана. Первая зона пространственно приурочена к Кожевниковскому и Шегарскому районам Томской области. В этом районе выделяется Осиновско-Бабарыкинская радиогеохимическии аномальная зона повышенного накопления урана, которая очень четко прослеживается в субмеридиональном направлении. В пределах Кожевниковского района она может быть связана с разгрузкой подземных вод в зоне Колыванского разлома. В Шегарском районе повышенные содержания урана пространственно приурочены к гранитоидам позднепалеозойского фундамента. Вторая зона накопления урана простирается вдоль южного обрамления Западно-Сибирской плиты в пределах Кузнецко-Алатаусского блока.

Radioactive heat production of Syrian territory

Gamma-ray spectrometry is applied to estimate equivalent uranium (eU), equivalent thorium (eTh), and K% of 748 rock samples collected from Syrian territory. The spectrometry results are used to evaluate and map the radioactive heat production (HP) of Syria. A new approach involving the multifractal technique with the concentration-number model (CN) and log-log plots was originally proposed and hence applied in this paper to map the distribution of uranium concentration and HP of Syria. This approach helps us to differentiate different eU and HP ranges related to different litho-types. The advantages of proposing and applying the fractal technique are that the boundaries of the distinguished radioactive ranges of eU and HP coincide well with the lithological boundaries, which gives this technique superiority over other traditional statistical methods. The fractal CN model with the use of log–log plots proves its efficacy in differentiating between several eU and HP populations that are related directly to the geology of Syrian territory. The fractal model shows four threshold break points corresponding to uranium concentrations of 3.1, 7.38, 16.6, and 28.8 ppm and an HP of 0.715, 1.86, 3.63, and 6.26 μW/m3, respectively. The highest HP ranges are mainly related to the phosphatic deposits, characterized by the highest uranium content.

Composition and structural features of two Permian parareptile (Deltavjatia vjatkensis, Kotelnich Site, Russia) bone fragments and their alteration during fossilisation

The Kotelnich vertebrate fossil site, one of the richest of the Permian period, is characterised by the excellent preservation of fossil remains due to their burial in a silty anaerobic environment similar to modern peat bogs. The aim of the work is to carry out a comprehensive study of the composition and structure of bone fragments of the Permian parareptile Deltavjatia vjatkensis, as well as that of its embedding rocks, to support further paleoecological and fossilisation reconstructions. Fossil bones and their surrounding strata were investigated using optical and scanning electron microscopy, Raman spectroscopy, X-ray diffraction and inductively coupled plasma mass spectrometry (ICP-MS). The carbonate-rich composition of the sediment was found to favour the preservation of the bone apatite. The mineral phase of the bone tissue corresponds to fluorapatite. Organic matrix vibration bands arising on the Raman spectra correspond to CH vibrations of lipids and proteins and possibly cholesterol. The obtained data indicate a high degree of integrity of both bone mineral phase and its organic proteinaceous residue. White blood cell (WBC)-like structures were detected, which possibly could be interpreted as leukocytes. Elemental mapping of fossil bones was used to reveal element distribution features (uniform or with zones of apparent enrichment-depletion) and secondary mineralisation zones. Ca, P, Mg, Mn and S are uniformly distributed through the bone; conversely, elevated quantities of Fe are assigned to cracks and large pores formed as a consequence of the decomposition of organic materials. As compared to bone apatite, the authigenic calcite filling of bone porosities is significantly depleted in terms of microelements. The apatite rare earth element (REE) composition of bone tissue, which is inherited from seawater, can be used for paleoreconstructions of redox conditions and water composition. La/Sm ratios (0.4–0.5), high Y/Ho ratios, high uranium content and high La/Yb ratios (2–3) in the bone apatite indicate the absence of recrystallisation during the late stages of diagenesis. A positive cerium anomaly detected in the bones indicates the presence of an oxidising and possibly alkaline environment during the early stages of diagenesis in shallow coastal basin of the Kotelnich paleolocality. It is shown that 10 to 20% of REE in bone apatite is derived from seawater absorption (hydrogenous source), with the remainder having been derived from host rock (lithogenic) sources.

Synthesis of amidoxime polymer gel to extract uranium compound from seawater by UV radiation curing

ABSTRACT A new amidoxime polymer gel for uranium extraction from seawater was successfully prepared by photoinitiated crosslinking polymerization. It involves UV-induced radical polymerization of acrylonitrile (AN) and methacrylic acid (MAA) monomers with crosslinking agent and photoinitiator: an alternative synthesis pathway to gamma radiation. Characteristic peaks of Fourier transform infrared spectroscopy (FTIR) indicated that nitrile group was completely converted into amidoxime group. Eight hours of 60 W UV curing was enough for polymer gel formation. For the 4 to 1 ratio of AN to MAA, crosslinking agent concentration of 1 g/100 mL-monomers and photoinitiator content of 60 mL/100 mL-monomer, maximum uranium adsorption capacity of 17.02 mg/g adsorbent in seawater was achieved for sample spiked with 10 ppm uranium. For seawater sample spiked with 2,245 ppm uranium, the adsorption capacity reached 432.41 mg/g adsorbent. The amidoxime polymer gel could be regenerated for at least eight cycles while retaining about 50% of the uranium uptake capacity. Thus, the present amidoxime polymer adsorbent is a high-efficiency seawater uranium recovery agent for both high and low uranium concentrations.

Radiometric and microbiological investigations of ore and waste samples with especial emphasis on suitable fungus for remediation processes

The capacity of the micro-organisms in ore transformations makes bioleaching technique a very interesting alternative to conventional processes. Radiometric studies indicate high uranium contents in ore and waste samples. This paper describes the suitable fungus species for mobilization of U from low-grade U ores and their resulting wastes. The high bioleaching efficiency in waste samples is mainly attributed to the presence of high sulphate contents in these samples which converted by the assistance of microorganisms into sulphuric acids and so, increase the bioleaching efficiency. Fungal leaching technique demonstrated an adequate recovery of uranium, with an efficient and cost-effective means from waste samples and respect to a reuse of waste for economic and environmental purposes

Determinations of uranium concentrations in soil, water, vegetables and biological samples from inhabitants of war affected areas in eastern Croatia (ICP-MS method)

The occurrence of elevated uranium levels in post-war areas raise concerns among populations, especially in areas affected by heavy bombardment and potential use of depleted uranium weapons. The aim of this study was to assess public exposure to the uranium Water, soil, vegetables, urine, serum and hair samples were collected for the first time in eastern Croatia and analysed using an inductively coupled plasma mass spectrometry (ICP-MS) method, in order to try to explain the possible origins of uranium in the population and environment. Urine, serum and hair samples were collected from 389 inhabitants. A large variation of uranium concentrations in urine, serum and hair samples was found in this study. The majority of urine, serum and hair samples from our study had uranium concentrations below the reference literature values. A higher uranium concentration in the hair of 4% of inhabitants, mostly from rural areas, could not be explained at this stage of research. A further, extended epidemiological study should be made of uranium in the region.

Extraction of Uranium(VI) and Plutonium(IV) with Tetra-Alkylcarbamides

ABSTRACTThe use of tetra-alkylcarbamides as novel extractants for the separation of uranium(VI) and plutonium(IV) by solvent extraction from spent nuclear fuels is investigated in this study. Batch extraction experiments show that tetra-alkylcarbamides strongly extract U(VI) with high distribution ratios. Plutonium(IV) can be co-extracted with U(VI) at high nitric acid concentration, while high U(VI)/Pu(IV) selectivities can be reached at lower acidity. Loading capacity experiments with high uranium concentrations show that alkyl chains longer than butyl are necessary to avoid third phase formation. Nevertheless, the viscosity of uranium-loaded solvents gets too high with alkyl chains longer than pentyl. Overall, this study shows that with TPU extractant (with four pentyl chains), an efficient co-extraction of uranium and plutonium can be reached (DU,Pu > 1) for a concentration of nitric acid higher than 4 mol•L−1, while the partition between uranium(VI) and plutonium(IV) could be operated even at 2 mol•L−1 nitric acid without redox chemistry.

Radioactive Background of Granito Madeira, North Amazonas, Brazil

Radionuclides of natural origin are present in rocks and soils but have no homogeneous distribution in the soil of the Earth. Volcanic rocks have a higher concentration of uranium and thorium. Thus, sites with this type of origin present as radiological abnormalities. An example is the Planalto de Poços de Caldas in Minas Gerais. Another example is the Granito Madeira - a rock formation located in the Amazonas State, 350 km north of Manaus. This work presents the results of the natural radiation monitoring of Granito Madeira. 30,000 dose rates were collected with a sodium iodide scintillator transported on tracks within the Floresta Amazônica. These data were treated and georeferenced. As a result, an annual dose relative to gamma radiation of 6.0 mSv.year-1 was obtained. This information was represented in a frequency histogram and in a map of Granito Madeira.

Flow-Electrode CDI Removes the Uncharged Ca-UO2-CO3 Ternary Complex from Brackish Potable Groundwater: Complex Dissociation, Transport, and Sorption.

Unacceptably high uranium concentrations in decentralized and remote potable groundwater resources, especially those of high hardness (e.g ., high Ca2+, Mg2+, and CO32- concentrations), are a common worldwide problem. The complexation of alkali earth metals, carbonate, and uranium(VI) results in the formation of thermodynamically stable ternary aqueous species that are predominantly neutrally charged (e.g ., Ca2(UO2)(CO3)30). The removal of the uncharged (nonadsorbing) complexes is a problematic issue for many water treatment technologies. As such, we have evaluated the efficacy of a recently developed electrochemical technology, termed flow-electrode capacitive deionization (FCDI), to treat a synthetic groundwater, the composition of which is comparable to groundwater resources in the Northern Territory, Australia (and elsewhere worldwide). Theoretical calculations and time-resolved laser fluorescence spectroscopy analyses confirmed that Ca2(UO2)(CO3)30 was the primary aqueous species followed by Ca(UO2)(CO3)32- (at circumneutral pH values). Results under different operating conditions demonstrated that FCDI is versatile in reducing uranium concentrations to <10 μg L-1 with low electrical consumption (e.g ., ∼0.1 kWh m-3). It is concluded that the capability of FCDI to remove uranium under these common conditions depends on the dissociation kinetics of the Ca2(UO2)(CO3)30 complex in the electrical field. The subsequent formation of the negatively charged Ca(UO2)(CO3)32- species results in the efficient transport of uranium across the anion exchange membrane followed by immobilization on the positively charged flow (anode) electrode.

The influence of different types of granite on indoor radon concentrations of dwellings in the South African West Coast Peninsula

ABSTRACTGranite commonly contains high concentrations of uranium, with subsequent high exhalation of radon gas. The geology of the West Coast Peninsula of South Africa is dominated by granite. No m...