Uranium Mining Research Articles

Study of an innovative optimisation method for repair and renewal of production wells in the central section of the Mynkuduk field

ABSTRACT This study was aimed at identifying geological, geochemical, geotechnical and technical factors affecting the efficiency of repair and renewal of the Central section of the Mynkuduk field. The study included data collection on the technical parameters of the wells, including their design, filter sizes, as well as geological and hydrogeological features of the field. An analysis of the relationships between technical well parameters, geological factors and repair and renewal efficiency was carried out. The methods of operation efficiency assessment and their compliance with the actual results were also analysed. The study revealed that the mode of operation of technological wells depends on many factors, including both objective and subjective. One of them is the consideration of geological features such as well designs and rock composition. The study revealed that the methodology used at the mine is flawed due to the use of wells with different operating periods to estimate average values. The results emphasise the importance of an integrated approach to repair and renewal work on process wells in uranium deposits, considering their different characteristics. This will optimise the operation processes, minimise the risks of emergencies and increase the efficiency of uranium production.

Uranium enrichment driven by paleomarine condition and event deposition: Insights from the lower Cambrian Niutitang Formation organic-rich shales in northeastern Guizhou, South China

Organic-rich shale related uranium (U) mineralization has attracted widespread attention as a strategic and clean alternative to fossil energy and a paleoceanic redox proxy. A comprehensive study of mineralogy, organic geochemistry and elemental geochemistry of the lower Cambrian Niutitang Formation organic-rich shales in northeastern Guizhou, South China was conducted to address this issue. SEM-EDS results showed that the U occurrence state in the Niutitang Formation shales is dominated by nanoscale U minerals, mainly including coffinite, brannerite, U-bearing apatite and U-bearing xenotime. Various states of U are closely associated with organic matter, apatite, pyrite and clay minerals. Based on geochemical indexes, paleomarine condition and event deposition jointly drove the U enrichment in the Niutitang shales, in which hydrothermal activities and/or volcanic eruptions increased U fluxes in seawater and euxinic environment with high primary productivity provided a favorable condition for U reduction. The adsorption, complexation and reduction of UO22+ by organic matter and the formation of uranyl phosphate complexes by the combination of phosphate and UO22+ accelerated U immobilization and enrichment from bottom water to sediments. The microbial activities (e.g., BSR) in this process created favorable euxinic conditions and released inorganic-phase P to provide available ligands for UO22+. The U enrichment models of the lower Cambrian Niutitang shales in northeastern Guizhou were established. This paper provides a new insight into the U enrichment mechanism in organic-rich shales, and may also have implications for the applicability of U as redox proxy and the exploration of organic-rich shale related U deposits.

Uranium mineralization in the Thrace Basin, NW Türkiye: Evidence from radiation-induced defects in detrital quartz and synchrotron XRF/XANES analysis

The Paleogene-Neogene Thrace Basin in northwestern Türkiye has long been known to host economic gas and oil resources and has recently been reported to potentially host sandstone-type uranium deposits in the Oligocene Süloğlu Formation. The latter discovery raises questions about the source and deposition mechanism of uranium mineralization in the basin. This contribution reports on the results of a detailed electron paramagnetic resonance (EPR) spectroscopic study of detrital quartz from four sandstone and one mudstone samples in the Süloğlu Formation and documents the distribution and speciation of uranium using combined microbeam synchrotron X-ray fluorescence maps (μsXRF) and microbeam X-ray near edge structure spectroscopy (μsXANES). The EPR spectra of quartz separates are characterized by the presence of diagnostic radiation-induced defects (i.e., silicon-vacancy hole centers H′3, H′4, and H′7 with gmax = 2.049, 2.034, and 2.018, respectively, and the oxygen-vacancy electron center E′1), formed by the bombardment of alpha particles emitted from uranium, thorium, and their unstable progenies. Moreover, notable decreases in the intensity of silicon-vacancy hole centers in the EPR spectra of quartz separates after partial dissolution with hydrofluoric acid, provide compelling evidence for the circulation of uranium-bearing fluids in the Thrace Basin. The μsXRF and μsXANES data reveal the occurrences of mixed U6+ and U4+ species in hematite partially replacing pyrite aggregates but dominantly U4+ in disseminated pyrite and illite in sandstones of the Süloğlu Formation. These results provide new insights into uranium transport, reduction, and deposition mechanisms, with important implications for better understanding sandstone-type uranium deposits in general and further exploration in the Thrace Basin.

Ambient Radiological Condition around an Operating Uranium Mill Tailings Disposal Facility at Turamdih, India

AbstractLarge quantity of the feed forms part of the solid waste (tailings) slurry in the low grade uranium ore processing plant at Turamdih in Singhbhum region of Jharkhand, India. Coarser size fraction of this waste is used for backfilling of the underground uranium mines and fine fraction is discharged into an engineered impoundment system or tailings pond. Since inception of the discharges, field expeditions have been performed as part of the comprehensive radiological monitoring program for the facility. The monitoring program broadly consists of ambient gamma dose rate, atmospheric 222Rn and long lived alpha activity measurement around the facility and the estimation of radionuclide in diverse environmental matrices collected from the adjoining sites. Findings reflect that the radiological conditions are comparable to the pre-existing background level adjoining the tailings pond impoundment. Further, measurements for more than a decade confirm that the atmospheric radon concentration profile just a few meters beyond the embankment is indistinguishable from the background.

Construction of a Bifunctional Redox-Site Conjugated Covalent-Organic Framework for Photoinduced Precision Trapping of Uranyl Ions.

The performance of covalent-organic frameworks (COFs) for the photocatalytic extraction of uranium is greatly limited by the number of adsorption sites. Herein, inspired by electronegative redox reactions, we designed a nitrogen-oxygen rich pyrazine connected COF (TQY-COF) with multiple redox sites as a platform for extracting uranium via combining superaffinity and enhanced photoinduction. The preorganized bisnitrogen-bisoxygen donor configuration on TQY-COF is entirely matched with the typical geometric coordination of hexavalent uranyl ions, which demonstrates high affinity (tetra-coordination). In addition, the presence of the carbonyl group and pyrazine ring effectively stores and controls electron flow, which efficaciously facilitates the separation of e-/h+ and enhances photocatalytic performance. The experimental results show that TQY-COF removes up to 99.8% of uranyl ions from actual uranium mine wastewater under the light conditions without a sacrificial agent, and the separation coefficient reaches 1.73 × 106 mL g-1 in the presence of multiple metal ions, which realizes the precise separation in the complex environment. Importantly, DFT calculations further elucidate the coordination mechanism of uranium and demonstrate the necessity of the presence of N/O atoms in the photocatalytic adsorption of uranium.

Enhancing U(VI) removal from highly acidic wastewater through the synergistic effect of diethylenetriaminepenta(methylenephosphonic) acid and meso-SiO2 on nanosized γ-Fe2O3

Wastewater from uranium mining activities is highly acidic and contains uranium, thereby posing severe risks to the ecological environment and human health. Accordingly, uranium purification is extremely crucial. Herein, we delicately designed a novel adsorbent of diethylenetriaminepenta(methylenephosphonic) acid (DTPMP) and meso-SiO2 modified γ-Fe2O3 (γ-Fe2O3@SiO2@DTPMP, denoted as FSD), and found that the adsorbent can remarkably boost the removal performance of U(VI) under highly acidic conditions. The removal efficiencies of U(VI) by FSD are 90.26 % and 99.81 % in strong acidic solutions of pH = 1.0 and pH = 2.0, respectively, which are much higher than most of the reported adsorbents. Importantly, FSD exhibits high adsorption capacity (51.45 mg/g) and excellent anti-interference, even the wastewater stream contained a lot of organic substances (e.g., fulvic acid), cations (e.g., K+, Na+, Mg2+, NH4+, Zn2+, Co2+, etc.), radioactive nuclides (e.g., Cs+ and Sr2+). After five cycles, the adsorption efficiency and desorption efficiency of FSD only reduced by 8.83 % and 9.61 %, respectively, which are mainly attributed to the unique structures and good chemical stability of FSD. The removal of U(VI) by FSD is a heterogeneous adsorption process which is dominated by chemical adsorption, mainly involving surface coordination complexation. Multiwfn wavefunction and VMD programs based on density functional theory (DFT) further analyzed and visualized the interaction sites and relative strengths of reactions. The results of detailed characterization analysis and theoretical calculations confirmed that the highly efficient U(VI) removal by FSD is mainly ascribed to the strong coordination of the phosphate groups and amino nitrogen atoms in DTPMP with UO22+. Therefore, this study provides a promising strategy for the removal of U(VI) in strongly acidic wastewater.

Microvolume analysis of 226Ra by inductively coupled plasma mass spectrometry: Environmental applications to high-resolution profile of wetland soil pore waters

BackgroundThe release to the environment of natural radionuclides like 226Ra due to human activities have raised concerns about human and ecosystem exposure. 226Ra’s resemblance to calcium and involvement in biological processes accentuate the importance of understanding its geochemical behavior and migration pathways. Soil and sediment pore waters provide valuable information but have proved to be challenging to analyze, requiring to push the limits of current sample preparation and detection methods often not scaled for low concentrated microvolumes of samples. A more efficient and accurate analytical method is therefore needed to get reliable data to support hydro-geochemical modeling. ResultsWe describe here a novel comprehensive approach for accurate 226Ra quantification in pore waters of a wetland located downstream of the former Rophin uranium mine. In order to highlight the migration of 226Ra between the different soil layers, microvolumes of soil pore waters were in situ sampled up to 50 cm depth employing Diffusive Equilibrium in Thin-Films (DET) probes. The workflow included spiking DET extracts with an in-house 228Ra tracer, specific solid-phase extraction with 50 mg of AnaLig Ra-01® resin, and elution fraction calcination. This process eliminated interferences and simplify the analysis matrix. Quantification relied on isotope dilution after measurement by ICP-MS hyphenated to a desolvator module and to a microsampler (150 µL injection). The resulting 1 cm-high-resolution profile revealed unusual 226Ra enrichment with depth, signs of Ra mobility from the solid contamination source. These elements are essential for assessing 226Ra distribution coefficients across soil horizons and subsequent wetland remobilization considerations. Significance and noveltyThis first methodological advance for 226Ra constitutes a significant step to understand 226Ra behavior i.e., to quantify its activity level, fluxes inside of wetland soils or at the interface overlying waters/sediments. Its potential extension to studies involving other elements underscores its broader applicability in environmental research. The findings contribute to evidence-based decision-making for environmental protection and management, aiding in the preservation of ecological integrity and human health.

Analysis of the Ecological Footprint from the Extraction and Processing of Materials in the LCA Phase of Lithium-Ion Batteries

The development of batteries used in electric vehicles towards sustainable development poses challenges to designers and manufacturers. Although there has been research on the analysis of the environmental impact of batteries during their life cycle (LCA), there is still a lack of comparative analyses focusing on the first phase, i.e., the extraction and processing of materials. Therefore, the purpose of this research was to perform a detailed comparative analysis of popular electric vehicle batteries. The research method was based on the analysis of environmental burdens regarding the ecological footprint of the extraction and processing of materials in the life cycle of batteries for electric vehicles. Popular batteries were analyzed: lithium-ion (Li-Ion), lithium iron phosphate (LiFePO4), and three-component lithium nickel cobalt manganese (NCM). The ecological footprint criteria were carbon dioxide emissions, land use (including modernization and land development) and nuclear energy emissions. This research was based on data from the GREET model and data from the Ecoinvent database in the OpenLCA programme. The results of the analysis showed that considering the environmental loads for the ecological footprint, the most advantageous from the environmental point of view in the extraction and processing of materials turned out to be a lithium iron phosphate battery. At the same time, key environmental loads occurring in the first phase of the LCA of these batteries were identified, e.g., the production of electricity using hard coal, the production of quicklime, the enrichment of phosphate rocks (wet), the production of phosphoric acid, and the uranium mine operation process. To reduce these environmental burdens, improvement actions are proposed, resulting from a synthesized review of the literature. The results of the analysis may be useful in the design stages of new batteries for electric vehicles and may constitute the basis for undertaking pro-environmental improvement actions toward the sustainable development of batteries already present on the market.

Radiological, environmental, and structural investigations of Wadi El Markh granitic rocks, southeastern desert, Egypt

The radiological and environmental hazards of Wadi El Markh granitic rocks were investigated, and magnetic data were used to delineate the structural framework and determine the bedrock depth in the area. The result displayed that geological structures influence the occurrence of uranium mineralization in this area and are mainly associated with altered granitic formations. The activity concentrations of radioisotopes in the regions studied showed a range of values: 238U varied between 345 and 1729 Bq.kg−1, averaging 980 Bq.kg−1; 232Th ranged from 73 to 162 Bq.kg−1, with an average of 120 Bq.kg−1; and 40K varied from 829 to 1790 Bq.kg−1, average 1245 Bq.kg−1. The measured concentrations of 238U, 232Th, and 40K in the analyzed granitic rocks samples exceeded the worldwide average of 35, 45, and 412 Bq.kg−1, respectively. The primary radiological risks related to these granitic rocks were associated with the gamma radiation emitted by the radioactive elements. The statistical assessment confirmed that the main contributors to the radiological risks were uranium, potassium, and associated minerals in the granitic rocks. The entire investigation region has been determined to exceed the permissible safe radiation dose rate limit of 1 mSv/year. As a result, the study determined that the granitic rocks in the surveyed area were deemed unsuitable for construction because of their elevated levels of radioactivity. The effects of pollution on the ecological system were evaluated using several ecological indices, including the Geoaccumulation index (Igeo), Contamination factor (CF), Degree of Contamination (Cd), Pollution Load Index (PLI), Potential ecological risk factor (Eri), and Potential Ecological Risk Index (RI). Based on Cd and PLI, 100 % of the samples were found to be very highly polluted to the ecological system and suggest deterioration if used. Regarding RI, the metals were arranged as Cd > As > Co > Cu > Pb > Cr > V > Zn, with considerable risk in all samples.

Release of Radioactive Particles to the Environment.

When environmental impact and risks associated with radioactive contamination of ecosystems are assessed, the source term and deposition must be linked to ecosystem transfer, biological uptake and effects in exposed organisms. Thus, a well-defined source term is the starting point for transport, dose, impact and risk models. After the Chornobyl accident, 3-4 tons of spent nuclear fuel were released and radioactive particles were important ingrediencies of the actual source term. As Chornobyl particles were observed in many European countries, some scientists suggested that radioactive particles were "a peculiarity of the Chornobyl accident." In contrast, research over the years has shown that a major fraction of refractory elements such as uranium (U) and plutonium (Pu) released to the environment has been released as particles following a series of past events such as nuclear weapons tests, non-criticality accidents involving nuclear weapons, military use of depleted uranium ammunition, and nuclear reactor accidents. Radioactive particles and colloids have also been observed in discharges from nuclear installations to rivers or to regional seas and are associated with nuclear waste dumped at sea. Furthermore, radioactive particles have been identified at uranium mining and tailing sites as well as at other NORM sites such as phosphate or oil and gas industrial facilities. Research has also demonstrated that particle characteristics such as elemental composition depend on the emitting source, while characteristics such as size distribution, structure, and oxidation state influencing ecosystem transfer will also depend on the release scenarios. Thus, access to advanced particle characteristic techniques is essential within radioecology. After deposition, localized heterogeneities such as particles will be unevenly distributed in the environment. Thus, inventories can be underestimated, and impact and risk assessments of particle contaminated areas may suffer from unacceptable large uncertainties if radioactive particles are ignored. The present paper will focus on key sources contributing to the release of radioactive particles to the environments, as well as linking particle characteristics to ecosystem behavior and potential biological effects.

Hydrothermal Uranium Mineralization in the Tuyukan Ore Field (Northern Transbaikalia): Time of Precipitation of the Pitchblende and Age of the Uranium Source

Hydrothermal Uranium Mineralization in the Tuyukan Ore Field (Northern Transbaikalia): Time of Precipitation of the Pitchblende and Age of the Uranium Source

Geochemical and detrital zircon U[sbnd]Pb geochronology of the qigequan formation in the yuejin 2 area: Implications for tectonics and uranium sources

The Yuejin 2 mining area lies within the Mangya region, situated on the northwestern periphery of the Qaidam Basin. Recently discovered, it harbors a medium-sized uranium deposit within the basin. Nonetheless, investigations into the sedimentary provenance and paleoclimate of the Neogene Qigequan Formation in this locale have been sparse. This study delves into a meticulous examination of petrogeochemical attributes and the detrital zircon UPb geochronology of sandstones from the Qigequan Formation within the mining area, aiming to discern their origins and tectonic context. By scrutinizing the trace and rare earth element signatures of the rocks, we discern that the lower strata of the Qigequan Formation primarily originate from felsic sedimentary sources, indicative of a continental island arc tectonic. Detrital zircon ages from the Qigequan Formation manifest primarily in three distinct periods: 169–292 Ma, 327–505 Ma, and > 670 Ma, corresponding with geological ages documented in the Altyn Tagh and East Kunlun Mountains orogenic belts. Predominantly, the Altyn Tagh orogenic belt and the Qimantag Mountains in the eastern Kunlun Mountains serve as the principal source of the Qigequan Formation. The chemical weathering index (CIA*) is 70.54, suggesting a moderate level of chemical weathering within the source region. Additionally, the angular morphology of the detrital zircon implies proximity between the source area and the basin. During the late sedimentary epoch of the Qigequan Formation, rapid uplift of the Altyn Tagh led to a notable rise in temperature within the Yuejin 2 area, transitioning from a reducing to an oxidizing environment. Surface water enriched with uranium and eroded source rocks gradually infiltrated the sand bodies of the lower Qigequan Formation. Interaction with reducing agents facilitated the enrichment and formation of ore. Paleoclimatic shifts instigated the oxidation–reduction sequence necessary for uranium mineralization. Favorable conditions, characterized by oxygen-rich paleo-water, facilitated the activation, migration, and re-enrichment of uranium. Moreover, the Himalayan movement acted as a driving force and a pivotal factor in creating the conducive conditions imperative for large-scale uranium mineralization in the area.

‘Lab Rats for Science’: Uranium Mining, Expellees, Public Health, and Narratives of Radiation Danger in Cold War West Germany, 1955–1968

In 1955–6, three thousand German-speaking men were ‘repatriated’ from Czechoslovak forced labour camps, where they mined uranium, to West Germany, where they demanded benefits for health damage from radiation exposure. These men connected their group's experiences to the fears and developments of early Cold War West Germany, personifying the health risks of the Atomic Age and citizens’ demands that their states offer protection from such risks. These men contributed to public awareness of radiation health risk and to ambivalence about safe ‘peaceful nuclear technology’ in the late 1950s and 1960s, earlier than is usually assumed. They further inspired concrete policy changes, especially in occupational health protection, illustrating that post-war responses to nuclear technology emerged from the intersection of longer historical experience, specialised local knowledge and grassroots activism, as well as from post-war scientific and political developments. It further shows long-lasting expellee influence in unexpected areas of West German policy.

Studies of radioactive minerals and geochemistry of uranium at the granitic rocks of Wadi Um Shillman Area, South Eastern Desert, Egypt

The northwestern part of Gabal Um Ara granitic pluton is represents a good example for uranium occurrence in the southeastern desert of Egypt. Among the different lithologies in the study area, the granitic rocks attract attention for more detailed geological, geochemical and radiometrical studies. Um Ara granitic masses cover an oval outline area of about 300 km2, which is characterised by moderate topography. The granitic rocks are classified as monzogranite and alkali feldspar granite. Both of them belong to the post-orogenic younger granite magmatic activity that intruded the Egyptian shield between 620 and 530 Ma. The intrusion of Um Ara monzogranite and alkali feldspar granite appears to have been controlled by deep-seated tectonic zones and block faulting. The studied area lies at southeast of Aswan City between 22ͦ 38′ 12˝–22ͦ 38′ 34˝ N and 33ͦ 47′ 27˝–33ͦ 48′ 14˝ E. Geochemically, the average concentration of the elements in North Um Ara granite shows that the relative abundance decreases gradually with decreasing incompatibility from Rb to Y. The common features are enrichment in more mobile elements Rb, Th and U. The monzogranite shows the lowest U and Th content, whereas the alkali-feldspar shows an enhanced contents of both elements, with average Th/U ratio = 3.0. the alkali-feldspar exhibits an expanded enrichment of Th relative to U. The U of the alkali-feldspar may be included within the structure of the refractory accessory minerals. The northern part of the Um Ara granitoids has subjected to different types of alterations. The radiometric survey of the northwestern part of Gabal Um area granitic pluton revealed the presence of several radioactive anomalies near the contact with the Dokhan volcanic and metavolcanic rocks in the north. Some visible uranium mineralisation of uranium minerals occur mainly along the NW, NE, E-W and N-S joints, of a highly sheared alkali feldspar-granite. Uranophane is visible secondary uranium mineral, characterised by bright yellow lemon colours and occurs mainly as filling fractures and joints associated with violet fluorite, iron and manganese oxides. The radioactive and accessory minerals studying and X-ray diffraction analysis that of the mineralised alkali feldspar-granite granite in the northwestern part of Gabal Um Ara granitic pluton revealed include the presence of fluorite, zircon, columbite, spessartine garnet whereas, the secondary uranium minerals are represented by uranophane, β-uranophane and kasolite. The hydrothermal origin was proposed as two possible alternatives for this uranium mineralisation.

Apatite Fission‐Track Thermochronology in the Tamusu Area, Bayingobi Basin, NW China, and its Geological Significance

AbstractThe Bayingobi basin is located in the middle of Central Asia Orogenic Belt, at the intersection of Paleo‐Asian Ocean and Tethys Ocean, as well as the junction of multiple tectonic plates. This unique tectonic setting underpins the basin's intricate history of tectonic activity. To unravel the multifaceted tectono‐thermal evolution within the southwestern region of the basin and to elucidate the implications of sandstone‐hosted uranium mineralization, granitic and clastic rock samples were collected from the Zongnai Mts. uplift and Yingejing depression, and apatite fission track (AFT) dating and thermal history simulation analysis were performed. AFT dating findings reveal that the apparent ages of all samples fall within the range of 244 Ma to 112 Ma. In particular, the bedrock of the Zongnai Mts. and Jurassic detrital apatite fission tracks have undergone complete annealing, capturing the uplift‐cooling age. Meanwhile, the AFT ages of Cretaceous detrital rocks are either equivalent to or notably exceed the age of sedimentary strata, signifying the cooling age of the provenance. A comprehensive examination of AFT ages and palaeocurrent direction analyses suggests that the Cretaceous source in the Tamusu area predominantly originated from the central and southern sectors of the Zongnai Mts. uplift. However, at a certain juncture during the Late Early Cretaceous, the Cretaceous provenance expanded to include the northern part of the Zongnai Mts. uplift. Based on the results of thermal history simulations and previous studies, it is considered that the Tamusu area has undergone four distinct tectonic uplift events since the Late Paleozoic. The first is the Late Permian to Early Triassic (260–240 Ma), which is associated with the closure of the Paleo‐Asian Ocean and the accretionary orogeny within the Alxa region. The second uplift event took place in the Early Jurassic (190–175 Ma) and corresponded to intraplate orogeny following the closure of the Paleo‐Asian Ocean. The third uplift event is the Late Jurassic to Early Cretaceous (160–120 Ma), which is linked to the East Asia's position as the convergence center of multiple tectonic plates during this period. The fourth uplift event is linked to the Late Early Cretaceous (112–100 Ma), driven either by the westward subduction of the eastern Pacific plate or the mantle upwelling resulting from the Bangong–Nujiang oceanic lithosphere subduction and slab break‐off. The primary stress orientation for the first three tectonic uplift phases approximated a nearly SN direction, while the fourth stage featured a principal stress direction of NW. The fourth tectonic uplift event of the Late Early Cretaceous and basaltic eruption thermal event during this period likely exerted a significant influence on the formation of the Tamusu sandstone‐hosted uranium deposit.

Acidovorax bellezanensis sp. nov., a novel bacterium from uranium mill tailings repository sites with selenium bioremediation capabilities

A Gram-stain-negative bacterial strain designated Be4T, belonging to the genus Acidovorax, was isolated from mining porewaters sampled in uranium mill tailings repository sites, located in Bellezane, near Bessines-sur-Gartempe (Limousin, France). Cells were facultative anaerobic, rod-shaped, non-endospore-forming and motile with flagella. The mean cell size was 1.25–1.31 μm long and 0.70–0.73 μm wide. Colonies were light yellow, opaque, circular, convex with smooth margins, and 1–2 mm in diameter. Growth occurs at 4–37 °C and between pH 5.5–9.0. It differed from its phylogenetically related strains by phenotypic and physiological characteristics such as growth at 4 °C, presence of acid phosphatase, naphthol-AS-BI-phosphohydrolase and β-glucosidase enzymatic activities, and fermentation of l-xylose and esculin. The major fatty acids were C16:0, C16:1 ω7c/C16:1 ω6c, C17:0 cyclo and C18:1 ω7c. Phylogenetic analysis based on 16S rRNA and 938 core genes, confirmed its placement within the genus Acidovorax as a novel species. Strain Be4T showed highest 16S rRNA sequence similarity to Acidovorax antarcticus (98.2 %), Acidovorax radicis (97.9 %), Acidovorax temperans (97.8 %) and Acidovorax facilis (97.7 %). The genome of strain Be4T is 5,041,667 bp size with a DNA G + C content of 65.15 %. By automatic annotation numerous sequences involved in the interaction with metals/metalloids including some genes related to Se uptake and selenite resistance were detected in its genome. The average nucleotide identity (ANI) values calculated from whole genome sequences between strain Be4T and the most closely related strains A. radicis and A. facilis were below the threshold value of 95 %. Thus, the data from the phylogenetic, physiological, biochemical, and genomic analyses clearly indicates that strain Be4T represents a novel species with the suggested name Acidovorax bellezanensis sp. nov. The type strain is Acidovorax bellezanensis Be4T (=DSM116209T = CECT30865T). This novel species, due to its unique isolation source, genomic analysis, and preliminary laboratory tests where it was able to reduce toxic Se(IV) to less harmful Se(0) in the form of nanoparticles, holds great potential for further investigation in bioremediation, particularly concerning Se.

Efficient uranium sequestration ability and mechanism of live and inactivated strain of Streptomyces sp. HX-1 isolated from uranium wastewater

Prokaryotes are effective biosorbents for the recovery of uranium and other heavy metals. However, the potential mechanism of uranium bioaccumulation by filamentous strain (actinobacteria) remains unclear. This study demonstrates the potential for and mechanism of uranium bioaccumulation by living (L-SS) and inactivated (I-SS) Streptomyces sp. HX-1 isolated from uranium mine waste streams. Uranium accumulation experiments showed that L-SS and I-SS had efficient uranium adsorption potentials, with removal rates of 92.93 and 97.42%, respectively. Kinetic and equilibrium data indicated that the bioaccumulation process was consistent with the pseudo-second-order kinetic, Langmuir, and Sips isotherm models. FTIR indicated that the main functional groups of L-SS and I-SS binding uranium were uranyl, carboxyl, and phosphate groups. Moreover, the results of XRD, XPS, SEM-EDS, and TEM-EDS analyses revealed for the first time that L-SS has biomineralization and bioreduction capacity against uranium. L-SS mineralize U(VI) into NH4UO2PO4 and CaU(PO4)2∙1.5H2O through the metabolic activity of biological enzymes (phosphatases). In summary, Streptomyces sp. HX-1 is a novel and efficient uranium-fixing biosorbent for the treatment of uranium-contaminated wastewater.

Enhanced microbial remediation of uranium tailings through red soil utilization

Seepage of uranium tailings has become a focus of attention in the uranium mining and metallurgy industry, and in-situ microbial remediation is considered an effective way to treat uranium pollution. However, this method has the drawbacks of easy biomass loss and unstable remediation effect. To overcome these issues, spare red soil around the uranium mine was used to enhance the efficiency and stability of bioremediation. Furthermore, the bioremediation mechanism was revealed by employing XRD, FTIR, XPS, and 16S rRNA. The results showed that red soil, as a barrier material, had the adsorption potential of 8.21–148.00 mg U/kg soil, but the adsorption is accompanied by the release of certain acidic and oxidative substances. During the dynamic microbial remediation, red soil was used as a cover material to neutralize acidity, provide a higher reduction potential (<-200 mV), and increase the retention rate of microbial agent (19.06 mL/d) compared to the remediation group without red soil. In the presence of red soil, the anaerobic system could maintain the uranium concentration in the solution below 0.3 mg/L for more than 70 days. Moreover, the generation of new clay minerals driven by microorganisms was more conducive to the stability of uranium tailings. Through alcohol and amino acid metabolism of microorganisms, a reducing environment with reduced valence states of multiple elements (such as S2−, Fe2+, and U4+) was formed. At the same time, the relative abundance of functional microbial communities in uranium tailings improved in presence of red soil and Desulfovirobo, Desulfocapsa, Desulfosporosinus, and other active microbial communities reconstructed the anaerobic environment. The study provides a new two-in-one solution for treatment of uranium tailings and resource utilization of red soil through in-situ microbial remediation.

Stabilization of Uranium in Acid Ore Wastewater through Hydrothermal Mineralization-Induced Crystallization.

Uranium [U(VI)] mining activity resulted in the discharge of uranium containing acid wastewater. It is necessary for immobilizing the uranium from wastewater to avoid its environmental pollution. In this work, a novel hydrothermal mineralization strategy is proposed for uranium stabilization. Three reaction systems such as Mg3(PO4)2 + UO22+, Mg2+ + PO43- + UO22+, and Mg2+ + PO43- + Mg3(PO4)2 + UO22+ were designed to investigate the uranium mineralization and stabilization performance. The consumed molar quantities of magnesium and phosphate were calculated to understand the mineralization mechanisms. The molar ratios of Mg/U and P/U in the experimental results were in agreement with those of thermodynamic calculation in the presence of dissolved Mg2+ and PO43- under the hydrothermal process. The calculated saturated index indicated the facile crystallization of uranium into the saleeite and chernikovite through hydrothermal mineralization at the pH value of 5 and 473 K. Crystallization into saleeite and chernikovite contributed to uranium stabilization, resulting in the negligible leaching rate of 5% due to the high crystallinity of 97.23%. Thus, hydrothermal mineralization of uranium crystallization into saleeite and chernikovite was promising for uranium stabilization with long-term stability.

Geological characteristics of early cretaceous volcanic rocks and analysis of metallogenic potential of uranium mineralization in Moganshan basin, northern Zhejiang province, China

The Moganshan Volcanic Basin is located in the northeastern section of the Ganhang volcanic-tectonic-uranium polymetallic metallogenic belt. To explore the uranium mineralization potential of these volcanic rocks, petrographic, elemental geochemical, zircon U-Pb chronology, and Sr-Nd-Pb isotope analyses were performed on the volcanic rocks in the Moganshan Basin. The results showed that the volcanic rocks within the Moganshan Basin were formed at 130.8 ± 2.0 Ma; In addition, they are Si-rich (SiO2 content of 72.98%–77.32%), alkali-rich (Na2O+ K2O, with ALK values of =7.15–9.74), and potassium-rich (K2O/Na2O content of 1.41–4.34), with light rare earth elements (Rb, Th Nd, Zr, and Hf). Further more, the volcanic rocks within the Moganshan Basin are deficient in Ba, Ta, Nb, and Sr, with a negative europium anomaly (δEu of 0.10–0.17), high ISr (0.71028–0.71160), low εNd(t) values (−6.43–5.77), and other characteristics. The geological characteristics of the volcanic rocks in the Moganshan Basin are the same as those of the volcanic rocks in eastern China, and the formation age is Early Cretaceous. The formation environment is intra-land extensional and tensional. The rock-forming material primarily originates from the upper crust and has a higher average uranium content than that in the Ganhang volcanic belt. Additionally, it is speculated that the Moganshan Volcanic Basin has good potential for uranium mineralization.