High Uranium Content Research Articles

Highly efficient extraction of uranium from seawater by natural marine crab carapace

The sustainable access to uranium resource is critical for the sustainable development of nuclear energy industry. The global seawater contains thousands of times more uranium reserves than that on the land and can be a promising supply of uranium. Nevertheless, extraction of uranium from seawater is challenging due to the complex seawater environment and it’s urgent to develop adsorbents that suitable for being used in seawater environment. Herein, inspired by the high uranium concentrations in natural marine animal carapaces, the grinded marine crab carapace is used for uranium extraction. The crystalline calcium carbonate in crab carapace is identified as functional components for uranium adsorption for the first time. The grinded crab carapace achieves a high uranium extraction capacity of 1.38 mg g−1 in natural seawater. The EXAFS analysis and DFT calculations reveal that uranyl ion from seawater is bound by forming coordination bonds between uranium atom and oxygen atoms from the carbonate group and between axial oxygen atom from uranyl ion with calcium atom. Considering the promising uranium binding ability in natural seawater, the marine crab carapaces are highly potential for being used in uranium extraction from seawater.

Rapid and sustained environmental responses to global warming: the Paleocene–Eocene Thermal Maximum in the eastern North Sea

Abstract. The Paleocene–Eocene Thermal Maximum (PETM; ∼ 55.9 Ma) was a period of rapid and sustained global warming associated with significant carbon emissions. It coincided with the North Atlantic opening and emplacement of the North Atlantic Igneous Province (NAIP), suggesting a possible causal relationship. Only a very limited number of PETM studies exist from the North Sea, despite its ideal position for tracking the impact of both changing climate and NAIP activity. Here we present sedimentological, mineralogical, and geochemical proxy data from Denmark in the eastern North Sea, exploring the environmental response to the PETM. An increase in the chemical index of alteration and a kaolinite content up to 50 % of the clay fraction indicate an influx of terrestrial input shortly after the PETM onset and during the recovery, likely due to an intensified hydrological cycle. The volcanically derived zeolite and smectite minerals comprise up to 36 % and 90 % of the bulk and clay mineralogy respectively, highlighting the NAIP's importance as a sediment source for the North Sea and in increasing the rate of silicate weathering during the PETM. X-Ray fluorescence element core scans also reveal possible hitherto unknown NAIP ash deposition both prior to and during the PETM. Geochemical proxies show that an anoxic to sulfidic environment persisted during the PETM, particularly in the upper half of the PETM body with high concentrations of molybdenum (MoEF > 30), uranium (UEF up to 5), sulfur (∼ 4 wt %), and pyrite (∼ 7 % of bulk). At the same time, export productivity and organic-matter burial reached its maximum intensity. These new records reveal that negative feedback mechanisms including silicate weathering and organic carbon sequestration rapidly began to counteract the carbon cycle perturbations and temperature increase and remained active throughout the PETM. This study highlights the importance of shelf sections in tracking the environmental response to the PETM climatic changes and as carbon sinks driving the PETM recovery.

Uranium remobilisation in anoxic deep rock-groundwater system in response to late Quaternary climate changes – Results from Forsmark, Sweden

Unusually high uranium (U) concentrations (up to 175 μg/L) have been measured in groundwater at depths between 400 and 650 m at the Forsmark site, eastern Sweden. Since it is unlikely that such high concentrations formed under the stagnant and low redox groundwater conditions that currently prevail, this study employs U-series isotopes to understand how the recent evolution (<1 Ma) of the flow system has influenced the observed U distribution. Material from fractures as deep as 700 m along the assumed flow route was subject to U-series disequilibrium (USD) measurements, as well as sequential extractions (SE) and U redox-state analyses that revealed the U-series activity ratios in the bulk and soluble fraction of the fracture precipitates. Uranium isotope data collected over several years of annual groundwater monitoring were scrutinized to evaluate the U sources and U exchange in fractures located in high-U groundwater sections. Numerical simulations with the experimental data were used to study evolution of U-series isotope composition in a fracture in the highest U section at ~500 m depth under various U mobility scenarios. The results show that U redistribution in fractures with certain dissolution/deposition flux ratios during periodic water intrusions, driven by glaciation and deglaciation events during the last 120 ka, can explain the U anomaly in the groundwater.

Human health risk assessment using Monte Carlo simulations for groundwater with uranium in southern India

Uranium naturally occurs in groundwater and its concentration is mostly controlled by the geology of an area. The regular human consumption of groundwater with uranium causes health effects and hence the assessment of radiological and chemical toxicity effects on humans is essential. Hence, the present study was carried out to assess the general hydrochemistry of groundwater in different geological formations of southern India and its relation to uranium as well as to estimate the health risks posed to humans due to consumption of groundwater with uranium using both deterministic and probabilistic approaches. Four river basins representing the major geological formations of southern India were chosen for this study, from where a total of 141 groundwater samples were collected in the year 2016 and analyzed for the concentration of major ions and uranium. The groundwater occurring in granites had high concentration of uranium followed by gneiss and charnockites. Radiological risks to humans were higher in granitic terrain of Bhima basin, where about 1 in 10,000 may get affected due to cancer. The chemical toxicity risks were higher for the people in granite and gneissic terrain of Bhima basin followed by the people in charnockite terrain of Vaniyar basin. The deterministic method has overestimated the actual risk in comparison to the probabilistic risk assessment. The sensitivity analysis indicates that increase of exposure frequency and ingestion rates increases the chemical risks, whereas decrease of body weight increases the chemical risk. Therefore, the probabilistic approach is much superior to deterministic method since it exhibits variability in the values. The current study highlights the risks to humans by consuming groundwater with uranium, emphasizing on the urgent need for supplying treated water to the community.

Mineralogical and geochemical changes in subsurface shales straddling the Ordovician–Silurian boundary in the eastern Kufra Basin, Libya

This paper reports on the elemental geochemistry of 47 shale samples from the uppermost Hirnantian–lowermost Rhuddanian Tanezzuft Formation, collected from drill core (depth interval 20.8–73.2 m) from borehole JA-2 at the eastern Kufra Basin, SE Libya. Eighteen of these samples were also analysed by X-ray diffraction. This study was carried out (i) to search for shales with high total organic carbon (TOC >3 wt%) and associated high uranium (U > 30 ppm) concentrations, commonly referred to as ‘hot’ shales, (ii) to test whether TOC and U correlate, (iii) to study the effects of surface weathering on the behaviour and mobility of major oxides, trace elements and rare earth elements (REE), and (iv) to examine the relationship of the elemental composition obtained in this study and Rock-Eval pyrolysis and kerogen data obtained in previous studies on the same core samples. The studied core can be divided into three intervals: upper weathered section (20.8–46.5 m, influenced by Quaternary weathering), unweathered section (46.5–68.5 m), and lower weathered section (68.5–73.9 m, influenced by latest Ordovician weathering). Overall, the shales have low TOC values (<1 wt%) and low U concentrations (<12 ppm). TOC and U do not show any correlation likely due to their low values. Hence, ‘hot’ shale has not yet been proven in this part of the Kufra Basin. Trace elements such as Mn and Sc show significant changes from the weathered into the unweathered core section. In contrast, the majority of the major oxides, trace elements and REE seem to be unaffected or at least largely unaffected by weathering processes. The exception is the transition from the unweathered section into the lower weathered section of the core. Here, most of the major oxides, trace elements and REE show either abrupt or gradual shifts towards lower or higher element concentrations. The observed whole-rock geochemical (e.g., K2O, Rb, Sr, Th/K) and mineralogical (e.g., kaolinite/illite, K-feldspar/quartz) changes suggest either a switch from one source area to another or, more likely, climatic influence. The deepest part of the core may have been influenced by a more humid and warm climate that has led to intensive chemical weathering and dissolution of K-feldspar. During the latest Hirnantian–earliest Rhuddanian a temporary emersion event may have occurred due to post-glacial rebound, which has led to the weathering of older strata.

Assessing Uranium Pollution Levels in the Rietspruit River, Far West Rand Goldfield, South Africa.

The Rietspruit is located in Gauteng Province, South Africa, within the Witwatersrand Basin. The basin is noted for its vast gold deposit. The river extends for about 60 km before joining the Vaal River. The aim of this study was to determine the concentration of uranium in the Rietspruit and the factors that influenced the concentration of U at each of the sites. The source of uranium in the river is the discharge from the gold mine and the mine wastes. Inductively coupled plasma mass spectrometry was used for water and sediment analysis in order to determine the concentration of U. High concentration of U was found in the river water and sediment, which is above the permissible limit of U. The water is used for irrigation of farmlands, cattle watering and for human consumption despite the high concentration of uranium in it. Ingestion of uranium is dangerous to human health. Due to the toxic nature of uranium, consumption of the water for domestic use and agriculture purpose must be discouraged.

Non-destructive aerial and terrestrial analysis of uranium isotopic activity by sensitive α-spectrometer for El-Sella site

Any comprehensive radioactivity surveillance for a specific site should be carried out by a sensitive airborne system (e.g. carried on aircraft) together with terrestrial sampling and analysis. In the framework of ore, environmental and nuclear materials monitoring and investigation, the activity and isotopic compositions signature are considered crucial factors that must be considered, determined and evaluated. In this work and based on previous aerial monitoring, a very sensitive hyper pure germanium detector (Hp-Ge) of 50% efficiency with the Genie 2000 software has been used for spectroscopic non-destructive assay (NDA) of radioactivity content for samples collected from the Egyptian eastern desert (El-Sella Site). The identification of specific signature isotopes through their characteristic gamma lines and a calculation of their specific activities, activity ratios of 235U/238U and 234U/238U and mathematically estimation of the natural enrichment percentage are very vital and nuclear forensic targets. The results of measurements, analysis and calculations show that the Site samples have high radioactivity, natural enrichment origin and high uranium concentration. The obtained results are given tabulated, depicted, discussed and compared with the recent nationally published work and the international levels and limits.

Phase distribution of uranium in matrices obtained by co-melting basalt and uranium-containing aluminum oxide

Safe disposal of nuclear waste is key to sustainable use of nuclear energy. Exploring safe and reliable disposal methods for nuclear waste has become a research hotspot. The phase distribution of uranium in matrices obtained by co-melting basalt and uranium-containing Al2O3 was examined for the development of a potential material for radioactive waste immobilization. The co-melting of basalt with UO3-containing Al2O3 produced matrices containing glass, plagioclase, and spinel as major phases. The highest uranium content (97 mass % UO3) was observed on the non-dissolved fragment of the Al2O3 grains. The titanium-containing complex oxide phase, supposedly, ilmenite, contained up to 62 mass % UO3. The glass phase exhibited an uneven distribution of uranium, with its content ranging ~ 5 to ~ 10 mass % UO3. Data on the leaching of uranium into H2O from the co-melt of basalt and UO3-containing Al2O3 were obtained.

U-Pb systematics of uranium-rich apatite from Adirondacks: Inferences about regional geological and geochemical evolution, and evaluation of apatite reference materials for in situ dating

High‑uranium apatite samples from iron oxide-apatite (IOA) deposits of the eastern Adirondack Mountains, New York, are evaluated as potential standards for in situ U-Pb dating of high-U apatite. Age data for these minerals also have implications for better understanding the geological evolution in the region. Secondary ion mass spectrometry (SIMS), and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) analyses of these samples show that they have high and variable uranium contents of 5–485 ppm. High-precision isotope-dilution thermal ionization mass spectrometry (ID-TIMS) dating yielded U–Pb errorchron ages of 907 ± 14 Ma (MSWD = 20) and 924 ± 13 Ma (MSWD = 547), showed disturbance in the U–Pb systems, and revealed radiogenic compositions of initial Pb (206Pb/204Pb ratios of 339 ± 48 and 162 ± 39). Nominal age calculations using assumed initial Pb isotopic compositions close to average terrestrial crustal Pb yield biased and older ages despite the radiogenic Pb isotopic composition of the apatites (206Pb/204Pb from 1300 to >4000). The apatite ages calculated using the measured initial Pb isotopic compositions are younger than the U–Pb ages of 1008.0 ± 3.2 Ma and 992.4 ± 7.7 Ma determined by SIMS for zircon cores and rims, respectively, separated from one of these ore samples. It indicates protracted fluid activity in the deposit that lasted for ~100 Ma after the ore formation, or later disturbance of the apatite. The time of U enrichment that we inferred from radiogenic composition of initial Pb is within uncertainties with primary ore crystallization, indicating that high 206Pb/204Pb ratios of initial Pb were caused by dissolution-reprecipitation of primary apatite.Despite the variability in U contents and disturbance of the U–Pb system in the apatites, our SIMS and LA-ICPMS analyses show that these samples can be used, with due caution, as reference materials (RMs) for dating apatite with similarly high-U concentration. They potentially provide more precise and accurate results compared to the usage of better behaved but lower-U apatite RMs due to improved counting statistics and reduced matrix effects, especially important for LA-ICPMS with less sensitive quadrupole mass analysers.The McClure Mountain apatite, a widely used reference for in situ dating, was used in the present study as a matrix-matched reference material for in situ LA-ICPMS analyses. We also analysed it by ID-TIMS and obtained more radiogenic Pb-isotopic data and more precise ages that are in agreement within uncertainties with the previously published result (Schoene and Bowring, 2006); combined data yielded a U-Pb errorchron age of 525.3 ± 1.7 Ma (MSWD = 70). The data corrected for initial Pb using the total U/Pb isochron yield the single Concordia age of 525.10 ± 0.75 Ma (MSWD = 1.1). Two independent ID-TIMS U–Pb studies support the use of this apatite as a primary RM for dating of low-U apatite with a normal composition of initial Pb. However, its small grain size and low U concentration (11–29 ppm) can cause elevated uncertainty in LA-ICPMS age determinations for unknowns. Better precision in our LA-ICPMS analyses was achieved using Madagascar (MAD1 and MAD2) apatite RM with U contents in the range of 28–58 ppm.

The Application of Geostatistical Analysis on Radiometric Mapping Data to Recognized the Uranium and Thorium Anomaly in West Sulawesi, Indonesia.

Mamuju Region in West Sulawesi, Indonesia is one of prospect area of uranium/thorium in Indonesia. High radiometric concentrations were located in Adang Volcanic Rocks. This formation is grouped as basaltic to intermediate rock and composed by lava, pyroclastic rocks, and tuff. Regional field radiometric mapping, including radiation dose rates, potassium, uranium, and thorium contents of soil and rock was conducted to identify the existence of radioactive minerals and prospect zones. Some radiometric anomalies are detected and probably related to hydrothermal alteration, leaching, and precipitation processes. Uranium anomaly (97,261 ppm) located in Mamuju River upstream, Botteng, Takandeang and Ahu area. The anomaly related to uranium leaching and precipitation processes in leucite basalt lava. Thorium anomaly (369,461 ppm) located in Pangasaan, Takandeang, Ahu, and Taan area. To expand this radiometric mapping, we characterized the reflectance of Landsat-8 imagery based on field measurement data. Based on circular structures identification, uranium/thorium anomaly are related to the existence of volcano vents on Adang Volcanic. Based on band rationing, high uranium contents distributed in the area with less ferromagnesian mineral, while thorium did not affect. These field based and remote sensing characterization results could be used as preliminary parameters to identify wide and detail prospects.

Cohort profile: four early uranium processing facilities in the US and Canada

Purpose Pooling of individual-level data for workers involved in uranium refining and processing (excluding enrichment) may provide valuable insights into risks from occupational uranium and external ionizing radiation exposures. Methods Data were pooled for workers from four uranium processing facilities (Fernald, Mallinckrodt and Middlesex from the U.S.; and Port Hope, Canada). Employment began as early as the 1930s and follow-up was as late as 2017. Workers were exposed to high concentrations of uranium, radium, and their decay products, as well as gamma radiation and ambient radon decay products. Exposure and outcome data were harmonized using similar definitions and dose reconstruction methods. Standardized mortality ratios (SMR) were estimated. Results In total, 560 deaths from lung cancer, 503 non-malignant respiratory diseases, 67 renal diseases, 1,596 ischemic heart diseases, and 101 dementia and Alzheimer's disease (AD) were detected in the pooled cohort of over 12,400 workers (∼1,300 females). Mean cumulative doses were 45 millisievert for whole-body external ionizing radiation exposure and 172 milligray for lung dose from radon decay products. Only SMR for dementia and AD among males was statistically significant (SMR=1.29; 95% confidence interval: 1.04, 1.54). Conclusions This is the largest study to date to examine long-term health risks of uranium processing workers.

Radon Concentrations in a Nuclear Reactor Center in Brazil.

Radiation workers are normally exposed to doses resulting from their day-to-day activities. Besides that, background radiation, such as radon, can contribute to the exposure rates. The radionuclide 222Rn is a noble gas belonging to the uranium series, and its indoor concentration in the air depends on the exhalation from surrounding soil and the exhalation from building materials. Radon exhaling from porous building materials containing high uranium concentrations can become a significant exposure factor in areas with limited ventilation. The objective of this study was to evaluate the 222Rn concentrations in the radiochemistry and radiometric laboratories in the nuclear reactor building of the Nuclear Reactor Center (CERPq) located in the Institute of Nuclear and Energy Research (IPEN), São Paulo, Brazil. Measurements were done using a Radon Gas Monitor, model RAD7, equipped with a solid-state alpha detector. A passive method (SSNTD) was also used, consisting of square pieces of C-39 foils (2.5 cm × 2.5 cm) placed within small diffusion chambers. The CR-39 detectors were etched in KOH 30% solution at 80 °C for 5.5 h in a constant-temperature bath. After etching, the detectors were washed, dried, and scanned using a microscope to obtain the track density measurements. The activity concentrations measured with both techniques varied from 52 to 103 Bq m-3 in the studied areas of the CERPq. These values may be compared to the reference level of 100 Bq m-3 established by the World Health Organization to ensure safety environments.

El Ramsa area, Southwestern Sinai, Egypt: radioactivity, mineralogy, and geochemistry studies

Um Bogma Formation represents the main target for uranium exploration at El Ramsa area. The gamma-ray spectrometric survey shows diverse measurements of radioactivity over the surveyed area, which reflects contrasting radioelement, contents for the exposed various rock types. The highest radio-spectrometric levels are located in the northeast part and scattered parts to the southwest of the study area. They are mainly associated with Um Bogma Formation. Seven uranium anomalous localities are recorded which can be used as exploration guides to explore further uranium anomalies. The highest radiometric uranium anomalies were recorded within gibbsite, carbonaceous shale, dolomite, marl, and ferruginous sandstone of Um Bogma Formation. The chemical investigations indicate enrichment in U, Cu, Mn, Cd, Ni, Zn, and Pb elements. It also reveals high uranium contents up to 640 ppm and a strong positive relation between uranium and both iron and aluminum oxides was noticed. Furthermore, high content of rare earth elements, reaching up to 5736 ppm with an average 4204 ppm, is reported in gibbsite samples. Uranium minerals such as vanuralite, sklowdowskite, and phosphuranulite were detected. The present study reveals that the source of uranium and other elements in El Ramsa area is the hydrothermal fluids which associated with the magmatic eruption during the Paleozoic events.

Study on the detrital zircon fission‐track ages from natural borehole samples in the Bohai Bay and Tarim basins with different thermal backgrounds

Zircon fission‐track thermochronometry was used as an effective indicator to investigate the thermal history of sedimentary basins with high temperatures, and fission‐track ages and annealing temperatures were very important parameters. We measured fission‐track ages and discussed the annealing behaviour of zircon fission track from natural borehole samples in the Bohai Bay and Tarim basins. The annealing temperature of the zircon fission track was approximately 220°C in the deep borehole samples of the Bohai Bay Basin with a high thermal background. However, the annealing temperature was approximately 170°C in the deep borehole samples of the Tarim Basin with a low thermal background. In Neogene–Quaternary, the heating rate ranged from 2 to 7°C/Ma in the Sk1 samples, and 4 to 18°C/Ma in the K1 samples. This explained that zircon fission track with different thermal backgrounds existed different annealing temperatures due to the different heating rates. The uranium concentration of the K1 samples mostly ranged from 16 to 1,500 ppm, with a few grains spread from &gt;1,500 to 3,000 ppm, while the Sk1 samples mainly distributed between 4 ppm and 350 ppm. The K1 samples with high uranium contents tended to accumulate much radiation damages and were less resistant to annealing and appeared to have a lower annealing temperature compared to zircons of lower uranium contents in the Sk1 samples. By properly understanding annealing behaviour and annealing temperature, zircon fission‐track thermochronometry could provide a correct explanation for fission‐track ages.

Processing technology for carbonate ore from the Argun deposit

Priargun Mining and Chemical Association has been producing uranium in the Streltsov ore field for more than 50 years. The main ore bodies with high content of uranium have been mined out during this period of time, and the uranium content has dropped in ore which is currently extracted. In connection with this, appraisal of the mineral resources and mineral reserves of Priargun MCA has been accomplished. The Argun ore is composed of a few process types—iron silicate and uranium, silicate–uranium–molybdenum, carbonate and uranium, carbonate and molybdenum, carbonate–uranium–molybdenum and rebellious ore (contains zirconium and brannerite). It is required to undertake technology-based rating and certification of the Argun ore. The autoclave leaching technology is found to be higher economically efficient as against the atmospheric leaching technology due to lower operating expenses. From the preliminary studies, four samples of anion-exchange resins are recommended for further testing: A500Y, BM77-14, D299 and Ambersep 920UXL SO4. These ion-exchangers were used to analyze their influence on sorption–desorption of uranium and molybdenum. All these ion exchangers had preserved their sorption capacity in 10 sorption–desorption cycles. Based on the studies into adsorption of uranium and molybdenum from leached slurry at the Argun deposit, the optimal sorbent for extraction and separation of uranium and molybdenum is Ambersep 920UXL SO4. Producibility of natural uranium to meet ASTM C 967-13 standards is analyzed on a laboratory scale. The produced uranium concentrate contains much less impurities than it is stipulated by International Standard Specification ASTM С 967-13. The action chart of processing of carbonate ore from the Argun and Zherlovoe deposits is developed and economically justified.

The presence of radioactive heavy minerals in prospecting trenches and concomitant occupational exposure.

Uranium, perhaps the most strategically important component of heavy minerals, finds particular significance in the nuclear industry. In prospecting trenches, the radioactivity of 238U and 232Th provides a good signature of the presence of heavy minerals. In the work herein, the activity concentrations of several key primordial radionuclides (238U, 232Th, and 40K) were measured in prospecting trenches (each of the latter being of approximately the same geometry and physical situation). All of these are located in the Seila area of the South Eastern desert of Egypt. A recently introduced industry standard, the portable hand-held RS-230 BGO gamma-ray spectrometer (1024 channels) was employed in the study. Based on the measured data, the trenches were classified as either non-regulated (U activity less than 1000 Bq kg-1) or regulated (with 238U activity more than 1000 Bq kg-1). Several radiological hazard parameters were calculated, statistical analysis also being performed to examine correlations between the origins of the radionuclides and their influence on the calculated values. While the radioactivity and hazard parameters exceed United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) guided limits, the mean annual effective doses of 0.49 and 1.4 mSv y-1 in non-regulated and regulated trenches respectively remain well below the International Commission on Radiological Protection (ICRP) recommended 20 mSv/y maximum occupational limit. This investigation reveals that the studied area contains high uranium content, suitable for extraction of U-minerals for use in the nuclear fuel cycle.

Application of gamma-ray spectroscopy and IR-spectroscopy methods for the purposes of ore geology in the Timan-Pechora Oil and Gas Province (the case of Ukhta Region)

Two express methods are presented in this paper. The first method is a high-resolution gamma-spectroscopic method based on a germanium detector, the second method is an IR-spectroscopic method. The applied complex of methods allows to determine the sources of uranium and thorium, identify the rhythms of uranium accumulation associated with regional events; identify areas with a high content of uranium due to the influence of local sources (faults, hydrothermal, etc.); determine the amount of authigenous uranium in the composition of total uranium; determine thermal maturity of organic matter in shales without their preliminary demineralization. To identify levels of increased uranium intensity in the high-carbon strata, a set of indicators has been proposed, which includes both applied indicators in practice of geological work and new indicators. New indicators have been tested on the collection of shale reference samples. For them, values ​​were established that characterize the processes of uranium accumulation and uranium removal. On the example of Ukhta Region according to the proposed indicators, the sections from the Vendian-Riphean to Domanic inclusive were interpreted. The performed work showed the possibility of comparing the calculated gamma-spectroscopic data with the data of other methods. This opens up a broader perspective for the use of express non-destructive gamma-spectroscopic method for detecting levels with a high content of uranium in the shale rocks, to which ore-bearing concentrations of a number of metals are also confined.

Determination of uranium and thorium concentrations in sediment samples by using solid state nuclear track detectors

In this study, uranium and thorium concentrations in the sediment samples collected from the Gulf of Izmit in Marmara Sea were determined using neutron radiography method and alpha-autoradiography method. Mean uranium concentrations calculated for the sediment samples collected from the boreholes S2, S3, S5, S8 and KS-2 were found to be 5.99 μg/g (3.58–8.16 μg/g), 4,59 μg/g (2.54–8.22 μg/g), 4.03 μg/g (2.13–6.9 μg/g), 3.71 μg/g (2.36–4.48 μg/g) and 2.81 μg/g (2.16–4.06 μg/g), respectively. The highest uranium concentration in all borehole samples was obtained from borehole S3 with a value of 8.22 μg/g at a depth of 77.00 m, followed by borehole S2 with a value of 8.16 μg/g at 76.95 m depth. These results also confirms the possibility of thermal sources at boreholes S2 and S3. The mean thorium concentrations in boreholes S3 and S8 were found to be 15.26 μg/g (9.60–17.49 μg/g) and 15.76 μg/g (13.89–17.37 μg/g), respectively. The highest thorium concentration in obtained samples from all boreholes was obtained in borehole S3 with a value of 17.49 μg/g at a depth of 77.00 m.

ГЕОХИМИЧЕСКИЕ ОСОБЕННОСТИ КРЕМНИСТЫХ И КРЕМНИСТО-КАРБОНАТНЫХ МЕТАСОМАТИТОВ В МЕЛОВЫХ И ПАЛЕОГЕНОВЫХ ОТЛОЖЕНИЯХ НИЖНЕГО ПОВОЛЖЬЯ

The chemical composition and microstructure of Paleocene quartzite sandstones and Upper Cretaceous siliceous-carbonate rocks in the Volgograd right bank of the Volga River have been studied. Numerous pipe-like channels, along which hot silica-saturated solutions flowed at the stage of sand cementation are found to have a two-layer structure. The inner layer consisting of dense quartzite has been enriched with ore elements (Fe, V, Cr, Mo, Ni, W, and Cu). Majority of detected ore phases is presented with reduced forms while minority is represented with sulfide and oxide ones. Siliceous-carbonate rocks contain high concentrations of strontium, chromium, molybdenum, tungsten, and uranium in addition to calcium in cold carbon dioxide solutions outputs.

Groundwater chemistry affected by trace elements (As, Mo, Ni, U and V) from a burning alum shale waste deposit, Kvarntorp, Sweden

Worldwide, black shales and shale waste are known to be a potential source of metals to the environment. This project demonstrates ongoing weathering and evaluates leaching processes at a 100-m-high shale waste deposit closed in the 1960s. Some deep parts of the deposit are still burning with temperatures exceeding 500 °C. To demonstrate ongoing weathering and leaching, analyses of groundwater and solid samples of shale and shale waste have been undertaken. Largest impact on groundwater quality was observed downstream the deposit, where elevated temperatures also indicate a direct impact from the burning waste deposit. Groundwater quality is largely controlled by pH and redox conditions (e.g., for arsenic, nickel, molybdenum, uranium and vanadium), and the mixture of different waste materials, including pyrite (acidic leachates) and carbonates (neutralizing and buffering pH). Analyses of shale waste from the deposit confirm the expected pyrite weathering with high concentrations of iron, nickel and uranium in the leachates. No general time trends could be distinguished for the groundwater quality from the monitoring in 2004–2019. This study has shown that black shale waste deposits can have a complex long-term impact on the surrounding environment.