Source Of Uranium Research Articles

Uranium Sources and Fluid Transport in Volcanic Mineralized Systems: an Example of Streltsovka Caldera, Russia with Reflection on Dornot, Mongolia

Uranium Sources and Fluid Transport in Volcanic Mineralized Systems: an Example of Streltsovka Caldera, Russia with Reflection on Dornot, Mongolia

Feasibility of breed-and-burn reactor core design with nitride fuel and lead coolant

The global demand for energy is constantly increasing, and reliable, sustainable energy sources are urgently needed. Nuclear energy is one such source, and many thermal reactors are currently in operation. As a result, a huge amount of depleted uranium has been stored, and reprocessing plants or fast reactors operating in breed-and burn (B&B) mode are necessary for effective utilization of uranium source. In the present paper, we investigate the feasibility of a Rotational Fuel-shuffling breed-and-burn reactor with Nitride fuel and Lead coolant (RFBB-NL) with neutronic and thermal-hydraulic analyses. In order to establish a high neutron-economy B&B mode, the core is established with a Rotational Fuel-shuffling (RF) scheme. The present study confirms the feasibility of a small LFR design functioning in B&B operating mode by optimizing core height and operating parameters. We kept the maximum temperatures of fuel, cladding, and coolant under their constraints by performing a steady state thermal-hydraulic analysis for the hot channel of a shorter core with higher power.

Effect of humic acid derived from leonardite on the redistribution of uranium fractions in soil.

Humic acids (HAs) are complex organic substances with abundant functional groups (e.g., carboxyl, phenolic-OH, etc.). They are commonly distributed in the soil environment and exert a double-edged sword effect in controlling the migration and transformation of uranium. However, the effects of HAs on dynamic processes associated with uranium transformation are still unclear. In this study, we used HAs derived from leonardite (L-HA) and commercial HA (C-HA) as exogenous organic matter and C-HA as the reference. UO2, UO3, and UO2(NO3)2 were used as the sources of U to explore the fractionations of uranium in the soil. We also studied the behavior of the HA. The incubation experiments were designed to investigate the effects of HA on the soil pH, uranium fraction transformation, dynamic behavior of exchangeable, weak acid, and labile uranium. The observations were made for one month. The results showed that soil pH decreased for L-HA but increased for C-HA. Under these conditions, uranium tended to transform into an inactive fraction. The dynamic behavior of exchangeable, weak acid, and labile uranium varied with the sources of HA and uranium. This study highlighted that HA could affect soil pH and the dynamic redistribution of U fractions. The results suggest that the sources of HA and U should be considered when using HA as the remediation material for uranium-contaminated soils.

Contrasting U-Pb geochronology and geochemistry of uraninite from the Xianshi and Xiwang uranium deposits, South China: Implications for ore genesis

The Xiazhuang uranium ore field contains eighteen uranium deposits and is one of the most important granite-related uranium ore producers in South China. Silicified vein-type and intersection-type uranium deposits are the two main types of uranium deposits in this ore field. To constrain the mineralization ages and sources of uranium of these two types of uranium deposits, we present geochemistry and U-Pb isotopic data of uraninites from the representative Xianshi intersection-type and Xiwang silicified vein-type uranium deposits in the Xiazhuang ore field. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb dating on uraninite from the Xianshi deposit yielded the crystallization age of 89.9 ± 2.1 Ma, which is consistent with the emplacement age (∼90 Ma) of NNE-trending diabase porphyrite dykes in this area. Chondrite-normalized rare earth element (REE) patterns of uraninite from the Xianshi deposit are characterized by slight enrichment of light REE relative to heavy REE and weakly positive Eu anomalies. Our study suggests the involvement of mantle-derived metals in the formation of the Xianshi deposit. In situ LA-ICP-MS U-Pb dating on uraninite from the Xiwang deposit yielded a weighted mean age of 51.3 ± 0.8 Ma, which overlaps the timing of the 55–45 Ma crustal extension event in South China. Uraninite from the Xiwang deposit has much higher contents of W (5768–11305 ppm), Nb (294–1301 ppm), and Y (3013–6263 ppm) than those of uraninite from the Xianshi deposit (W = 291–371 ppm, Nb = 3–14 ppm, and Y = 1658–3149 ppm). Uraninite from the Xiwang deposit has “gull-winged” chondrite-normalized REE patterns with pronouncedly negative Eu anomalies, which resemble whole-rock REE patterns of the Maofeng and Xiazhuang granites. This study suggests that the Maofeng and Xiazhuang granites are probably the primary source of uranium for the Xiwang deposit.

Historical changes of 236U/238U and 235U/238U isotopic ratios in Tokyo Bay from the 1960s to the 2000s

We examine the historical changes of 236U/238U and 235U/238U in a sediment core collected in Tokyo Bay and elucidate the anthropogenic sources of uranium in the 1960s–2000s. Uranium-236 was detected in samples deposited in the 1960s–2000s, and the 236U/238U ratio of the sediment core shows peak values in the 1970s. The 235U/238U isotopic ratios in samples deposited in the early 1960s are almost identical to that of natural uranium, implying that the 236U might have originated from global fallout. A decrease in 235U/238U was observed in the late 1960s–2000s, suggesting that depleted uranium from nuclear fuel reprocessing increased the 236U/238U ratios in the sediment. The 236U/238U values in sediments from the 1980s–2000s were lower than those in the 1970s but considerably higher than those in the 1960s, suggesting that the main source of depleted uranium still remains around Tokyo Bay. Our results demonstrated that the depleted uranium released in the 1970s should be considered as an important end-member when using uranium isotopic ratios as environmental tracers in closed aquatic environments around industrial cities.

Location of Uranium‐Rich Brines Determines the Distribution and Grade of Unconformity‐Related Uranium Deposits

AbstractRecent fluid inclusion analysis indicates that uranium‐bearing brines were present in both the sandstone and the basement at the time of ore genesis in the Athabasca Basin, Canada. However, the question of how the location of uranium‐rich brines controls the formation of unconformity‐related uranium deposits remains unresolved. In this study, four reactive flow modeling scenarios are designed to address this outstanding issue. Our numerical results confirm that the basement‐hosting uranium‐rich brines are capable of forming high‐grade concentrated uranium deposits in the footwall region of the fault zone below the unconformity interface. In contrast, the sandstone‐hosting uranium‐rich brines lead to the formation of low‐grade sheet‐like uranium mineral precipitates above the sandstone layer rather than in the basement. Therefore, this study reveals that unconformity‐related uranium deposits tend to be formed when the basement unit serves as the main uranium source. Taking the sandstone layer as the main uranium source, no unconformity‐related uranium deposits can be formed since the resultant uranium precipitation has no spatial relation with the unconformity interface.

Source-to-sink analysis of Mesozoic–Cenozoic sandstone-type uranium deposits in the Qaidam Basin

Accurate evaluation of uranium sources and identification of their spatiotemporal correlations with uranium deposits (or sinks) in sedimentary basins are important for exploring sandstone-type uranium deposits. This study examines the source-to-sink system of Mesozoic–Cenozoic sandstone-type uranium deposits in the Qaidam Basin (QB) through a literature review in conjunction with logging and seismic data and yields the following findings. (1) The uranium-supplying capacity of a source rock in the uranium source area depends on primarily its type and to a lesser extent, the tectonic zone where it is located and the episode during which it formed. (2) The initial uranium content, U0, is the core parameter for classifying and evaluating the uranium-supplying capacity of a source rock. At U0 > 1.5 ppm, uranium begins to migrate from a source rock. The uranium variation coefficient, ΔU, and the amount of uranium migration, ΔUt, decrease continuously to –55 % and –5 ppm respectively as U0 increases up to 9.5 ppm, which suggests that at most 5 ppm of uranium in the source rocks can migrate away. As U0 increases beyond 9.5 ppm, ΔU and ΔUt fluctuate around –55 % and –7 ppm respectively, which suggests that approximately 7 ppm of the uranium in the source rocks can migrate away. (3) Of the different types of rocks, silicic igneous rocks (including both intrusive and volcanic igneous rocks) and granitic gneisses have the highest uranium-supplying capacity; intermediate igneous rocks and gneisses come second; mafic–ultramafic igneous rocks and the other metamorphic rocks (except granitic gneiss and gneiss) come third. Of the sub-source areas (tectonic zones), the western segment of the Eastern Kunlun and the Qiman Tagh have the highest uranium-supplying capacity; the Central and Southern Altyn Tagh come second; the others come third. (4) Uranium sources are the fundamental prerequisite for the formation of uranium sinks. Other geological factors control the specific formation process of uranium sinks as well as their spatiotemporal distribution patterns. For QB, the most economic and prospective uranium sink, Neogene formations of Gy anticline, was fed by the source areas which had the highest uranium-supplying capacity. This suggests that the Neogene of WEK anticline belt, Quaternary of Kumukol Basin and Qarqan River Basin are the most noteworthy metallogenic prospective areas. The uranium-source evaluation scheme and “source-to-sink” ore exploration approach introduced in this study have practical value for advancing the exploration of uranium deposits in sedimentary basins in northern China and other parts of the world.

Constraints on Sandstone-Type Uranium Deposits by the Tectonic Uplift and Denudation Process in the Eastern Junggar Basin, Northwest China: Evidence from Apatite Fission Track and Detrital Zircon U-Pb Ages

The uplift and denudation history of the orogenic belt and the basin–mountain coupling process have directly or indirectly affected the generation, scale, and preservation of sandstone-type uranium deposits in the eastern Junggar Basin by controlling the uranium source, lithology, facies, hydrogeology, post-generation modification, and other mineralization conditions. Taking the eastern Junggar Basin as the research area, this study proposes the constraints on sandstone-type uranium deposits by the tectonic uplift and denudation history of the orogenic belt in the basin using the apatite fission track (AFT), detrital zircon geochronology, and other methods. The results of the AFT age test and thermal path simulation indicate that the orogenic belt in the eastern Junggar Basin underwent four rapid uplifts; (from approximately 300 Ma to approximately 250 Ma, from approximately 130 Ma to approximately 90 Ma, from approximately 65 Ma to approximately 30 Ma, and from approximately 20 Ma to 0 Ma). Moreover, the timing of the uplift has a spatial trend of gradually becoming younger from south to north. The detrital zircon U-Pb age test showed that the sediment source area of the basin is mainly distributed in three age intervals, i.e., 460–390, 360–270, and 190–170 Ma. The comprehensive evaluation of the clastic sediment composition, stratigraphic distribution of the erosion source area, and thermal history showed that a large amount of exposed Carboniferous–Permian granites in the Qinglidi and Karameri Mountain erosion source areas contributed dominant sediment material and uranium sources for the Triassic and Middle and Lower Jurassic strata in the basin. The Ordovician–Early Devonian granites only provided sediment sources for the Upper Triassic and Lower Jurassic strata in the basin. Altay Mountain contributed some sediment sources for the Middle and Upper Jurassic strata after the magmatic activity and rapid uplift occurred in the Middle Jurassic. Based on the comprehensive analysis of the influence of the tectonic uplift process of the orogenic belt and the transformation of material source areas on uranium mineralization, the granites in the erosion source areas are proposed to contribute both external and internal uranium sources for uranium mineralization. Uranium mineralization mainly occurred in the tectonic retreat period after the rapid uplifts of the Cretaceous and Paleogene. It was terminated by the intensive uplift-induced stratigraphic deformation in the Miocene.

Detrital zircon U–Pb geochronology and Hf isotopes of Mesozoic through Cenozoic sandstones from the southern Junggar Basin, NW China: Implications for the provenances and uranium source

Junggar Basin is an important exploration zone for sandstone‐hosted uranium deposits in north‐west China. However, neither the provenance of the host sandstone nor the uranium supply capacity of the potential source rocks have been well evaluated. To determine the provenances of the Mesozoic to Cenozoic sandstone grains and to evaluate relationships between the uranium source and the detritus provenances, a field investigation was performed at the Honggou section in the southern Junggar Basin. U–Pb geochronology and Hf isotopes were obtained from populations of detrital zircons from Jurassic through Palaeogene sandstones. The detrital zircon U–Pb ages display three main groups: 145–190 Ma, 250–360 Ma, and 360–460 Ma. The detrital zircon age distributions and the Hf isotopic characteristics of the sandstones correspond to different igneous rock units within the North and Central Tianshan Mountains. Therefore, the changes in the relative proportions of the zircon age populations indicate that there were major shifts of the provenance areas for the sandstones throughout the Early Jurassic to Palaeogene interval. The majority (92%) of Hf isotope εHf(t) values are positive and in the range of +0.7 to +15.5, which indicates that the majority of the zircons had crystallized in igneous rocks that were mainly derived from juvenile crust or depleted mantle. The majority (93%) of the two‐stage model ages (TDM2) are less than 1.8 Ga, thereby indicating the source of the majority of the igneous rocks was from the melting of ancient Meso‐Proterozoic juvenile crust. Carboniferous–Permian intermediate‐felsic igneous rocks in the Tianshan Mountains may be the primary source of released mobilized uranium and uranium‐enriched siliciclastics into the southern Junggar Basin. This study will assist in future uranium prospecting in this region.

Experimental and Simulated Spectral Gamma-Ray Response of a NaI(Tl) Scintillation Detector used in Airborne Gamma-Ray Spectrometry

Abstract. The objective of this work is to simulate the spectral gamma-ray response of NaI(Tl) scintillation detectors for airborne gamma-ray spectrometry (AGRS) using the state-of-the-art multi-purpose Monte Carlo code FLUKA. The study is based on a commercial airborne gamma-ray spectrometry detector system with four individual NaI(Tl) scintillation crystals and a total volume of 16.8 L. To validate the developed model, radiation measurements were conducted using 57Co, 60Co, 88Y, 109Cd, 133Ba, 137Cs and 152Eu calibration point sources with known activities and source-detector geometries under laboratory conditions. In addition, empirical calibration and resolution functions were derived from these measurements combined with additional radiation measurements adopting natural uranium, thorium and potassium volume sources. The simulation results show superior accuracy and precision compared to previous AGRS simulation models with a median relative spectral error < 10 % for most of the radiation sources. Moreover, the implementation of a lower level discriminator model and detailed modelling of the laboratory result in a significant improvement in model accuracy for spectral energies < 100 keV compared to previous studies. Yet thorough statistical analysis incorporating statistical and systematic uncertainty estimates revealed statistically significant deviations between the simulated and measured spectra in the spectral region around the Compton edge, which could be attributed to the scintillator non-proportionality. These findings imply that the linear energy deposition model applied in this and previously developed AGRS simulation models should be revised and considered to be replaced by more accurate non-proportional models.

Clearance measurement for concrete waste generated by the decommissioning of uranium processing facilities

Decommissioning is planned at nuclear facilities that have been discontinued. We examined the evaluation method of uranium radioactivity for concrete waste generated by the decommissioning of nuclear facilities. Since the peaks of Ac-228, Tl-208, and K- 40 are derived from concrete waste, it is difficult to distinguish the 1001 keV peak emitted from the uranium source. We have derived a formula to correct gamma rays from concrete and the environment, and the amount of uranium was quantified. When the weight of concrete waste is about 300 kg, if the weight of uranium is 3 g or more, it can be quantified within a relative error of about 30%. Measurement tests were performed using homogeneous simulated concrete waste. Since uranium contamination is on the concrete surface at the uranium processing facility and small chunks generated by scraping the concrete surface will be stored in a drum and measured, it seems that the test of homogeneous concrete reflects the actual waste.

Tracing geochemical sources and health risk assessment of uranium in groundwater of arid zone of India

Water quality degradation and metal contamination in groundwater are serious concerns in an arid region with scanty water resources. This study aimed at evaluating the source of uranium (U) and potential health risk assessment in groundwater of the arid region of western Rajasthan and northern Gujarat. The probable source of vanadium (V) and fluorine (F) was also identified. U and trace metal concentration, along with physicochemical characteristics were determined for 265 groundwater samples collected from groundwater of duricrusts and palaeochannels of western Rajasthan and northern Gujarat. The U concentration ranged between 0.6 and 260 μg L−1 with a mean value of 24 μg L−1, and 30% of samples surpassed the World Health Organization’s limit for U (30 μg L−1). Speciation results suggested that dissolution of primary U mineral, carnotite [K2(UO2)2(VO4)2·3H2O] governs the enrichment. Water–rock interaction and evaporation are found the major hydrogeochemical processes controlling U mineralization. Groundwater zones having high U concentrations are characterized by Na–Cl hydrogeochemical facies and high total dissolved solids. It is inferred from geochemical modelling and principal component analysis that silicate weathering, bicarbonate complexation, carnotite dissolution, and ion exchange are principal factors controlling major solute ion chemistry. The annual ingestion doses of U for all the age groups are found to be safe and below the permissible limit in all samples. The health risk assessment with trace elements manifested high carcinogenic risks for children.

Review on Granitic Rocks in Sumatra: Intrusion Process, Classification, Mineralization and Potential Uses

Granitic rocks are widely distributed in Sumatra and surrounding areas. These granitoids are classified into several granite provinces of Southeast Asia with different intrusion processes and specific characteristics. This paper aims to review the intrusion of granitic rocks in Sumatra and describe the opportunities associated with it. Granite rocks are used to manufacture cultural heritage, works of art, and ornaments because of their weathering resistance, color diversity, and hardness characters. S-type granite intrusion in Sumatra might be associated with tin mineralization while silver-gold with the I-type. Theoretically, granite contains more REE than other igneous rocks. Mining and extraction difficulties complicate the direct REE exploitation from fresh granite. A-type granite relatively contains more REE than the other types, but this type of granite is not correlated with certain provinces. Indonesia has a tropical climate which is prone to weathering. Therefore, it is possible for REE and/or bauxite enrichments in the granite weathering horizon. Granite is assumed to be a potential source of uranium and thorium, especially for the S-type, because it is formed through the compression of sediments that can absorb these radioactive elements from the continental crust.

Effect of genetic properties of Khiagda uranium deposits on the choice of in-situ leaching technologies

Hydrogenous uranium deposits of Khiagda ore field have no equal among commercial uranium reserves recovered by the in-situ leaching (ISL) technology. Khiagda JSC carries out ISL of uranium from four uranium deposits in Khiagda field, namely, Khiagda, Vershinnoe, Istochnoe and Kolichkan. As compared to ore occurrences in alluvium in large paleovalleys and in syneclise-type and grabensyncline type artesian basins in Uzbekistan, Southern Kazakhstan, South Australia and in the TransUrals, Khiagda ore field differs by the fact that uranium sources in the catchment area locate at a distance of a few tens of kilometers from the uranium concentration zones in the reducing geochemical barriers. At the Vitim deposits, the zones of uranium removal from the Vitimkan Complex granite by surface water and groundwater and the zones of uranium concentration under the action of syngenetic and epigenetic reducers in the alluvium–proluvium deposits in paleovallyes are very closely spaced at tens and hundreds of meters to a few kilometers. Some other differences include the mostly phosphate rather than oxide and silica composition of uranium minerals and the near-modern age of ore—1.5–12.5 million years. The breakthrough mining technologies are proposed, such as: nonregular accessing of ore bodies with the nonuniform distribution of uranium; use of sodium nitrite as a uranium oxidizer; groundwater resources management in mining of weakly watered deposits; direct determination of uranium content of ore using the method of neutron–neutron logging. These technologies enhance efficiency of ISL. The further research aimed to improve the process designs is proposed to be focused on optimization of ISL borehole patterns as well as on improvement of groundwater resources management in mining weakly watered deposits.

Natural Radioactivity and Radiological Implications of Stream Sediments at Wadi Aidib Area, South Eastern Desert, Egypt

Wadi Aidib lies at the extreme southern part of the Eastern Desert, Egypt, between 22o15'- 22o21' N and Longitudes 36o20'-36o30' E. Landsat ETM+ false color composite image (bands 3, 2, 1) was used for regional discrimination for different rock types and provide an excellent base map for the study area, morphological features of the stream deposits of the study area were known from Landsat ETM images, in addition to several field observations. The studied stream sediments accumulate in the form of alluvial fans. They are mainly composed of sands, gravels, boulders and contain some heavy valuable minerals which are derived from metavolcanics, metasediments, quartz diorite, biotite and alkali feldspar granites. Heavy liquid separation and magnetic separation techniques in addition to microscopic examination for the studied stream sediment samples were applied to identify the heavy minerals in these sediments. These minerals are represented by magnetite, ilmenite, rutile, garnet, zircon, monazite and Green silicates. The distribution of some elements in the study area is clear that they are concentrated near the outcrops of granites. The radionuclide concentrations were measured in different stations using a calibrated gamma-ray portable detector (RS 230) and the heavy minerals causing radioactivity were separated by heavy liquids and determined by binuclear and environmental scanning electron microscopes. Uranium ranges between 5.25 and 32.05 ppm with an average of 16.63 ppm, Th between 4.4 and 17 ppm with 11.34 ppm as an average and potassium fall between 1.8 and 5.15% with an average of 3.4 %. Correlation between soil radioactivity and its mineralogical content indicate that the high radionuclides contents are mainly attributed to the presence monazite which is the principal source of both uranium and thorium. Uranium high concentrations could be related to the metamict zircon. Absorbed Dose Rate (D), annual effective dose equivalent radium equivalent activity, external and internal hazard index, in addition to activity gamma index caused by gamma emitting natural radionuclide are determined from the obtained values of 238U, 232Th and 40K. Fairly, some of the studied stations do not satisfy the universal standards. 40K plays the main and most important role in dose rate contribution.

Source, mobilization and distribution of uranium in a complex aquifer system: a spatial and temporal evaluation using geochemical, statistics and GIS approach

Source, mobilization and distribution of uranium in a complex aquifer system: a spatial and temporal evaluation using geochemical, statistics and GIS approach

KAJIAN EKONOMI PEMBANGKIT LISTRIK TENAGA MIKRO HIDRO (PLTMH) BENUIS

energy as a source of electrical energy, both solar, wind, hydro and other renewable energy sources, a potential source of uranium in Indonesia.What needs attention is how to design energy policies to use each type of energy optimally, so as to avoid over-exploitation of fossil energy on the one hand, and on the other hand prevent neglect of renewable energy sources. In an effort to overcome this, the central and regional governments have made new policies that encourage the use of renewable energy sources as an alternative to supplying electricity to rural communities.The aims and objectives of the Feasibility Study Preparation Activity for the Benuis Micro-hydro Power Plant (PLTMH) Benuis Village, Selimbau District are; Availability of technical documents that describe the detailed design of the PLTMH and the Budget Plan (RAB) for the Benuis PLTMH Benuis Village. As a proposal for the construction of network facilities and infrastructure electricity..

Uranium in groundwaters: Insights from the Leinster granite, SE Ireland

Uranium concentrations in groundwaters from >100 private wells in the Caledonian Leinster Granite Batholith of SE Ireland range from a few μg/l to >300 μg/l. Approximately 10% of the wells exhibit uranium concentrations that exceed the current WHO provisional guideline of 30 μg/l and a further 10% exceed the original WHO guideline value of 15 μg/l. New whole-rock geochemical analyses and laboratory batch leaching experiments confirm the granite as the ultimate source of the groundwater uranium, but carbonate-bearing glacial deposits that overlie the granite play an important role in facilitating the generation of soluble and mobile anionic uranyl carbonate complexes. Whilst the granite has average uranium concentrations broadly similar to other Irish and British Caledonian granites, it is enriched locally in uranium, with whole-rock values up to c. 30 mg/kg. Uraniferous zircon, apatite, monazite and associations with secondary Fe-bearing oxide minerals were detected in drillcore whole-rock samples that had the highest uranium concentrations, but uraninite was not detected. Broad positive correlations between groundwater uranium concentrations and bicarbonate alkalinity and electrical conductivity are found in both the sampled groundwaters and in laboratory leachates of the granite and surficial glacial deposits. Leachates from the granite had approximately an order of magnitude higher uranium concentrations compared with those from the overlying limestone-bearing glacial tills. (234U/238U) ratios for the groundwaters and the leachates always exceed unity, indicating preferential leaching of loosely bound radiogenic 234U from mineral surfaces or grain boundaries into the groundwaters, rather than wholescale dissolution of the primary uraniferous minerals in the granite. Strontium isotopes ratios in the groundwaters constrain the balance between limestone and granite-derived Sr, and by extension the sources of dissolved Ca. These data indicate that calcite dissolution is the main source of dissolved calcium, highlighting the role of weathering of overlying limestone-bearing glacial tills during recharge in determining the geochemistry of the groundwaters. Geochemical modelling indicates that in the oxidising groundwaters of the study area U6+ is dominant, in the form of UO2(CO3)3−4 at the high pH values (7.49–7.69) of waters from wells overlain by limestone-bearing till. By contrast, in a small number of wells overlain by granite-bearing till, modelling indicates that the dominant species is UO2(CO3)2−2 reflecting their lower pH (6.22–6.30). Overall, carbonate species play a major role in uranium solubility and mobility in these granite-hosted groundwaters.

Geological Characteristics and Control Mechanism of Uranium Enrichment in Coal-Bearing Strata in the Yili Basin, Northwest China─Implications for Resource Development and Environmental Protection

Uranium enrichment is considerably prevalent in Jurassic coal-bearing strata in the Yili Basin. A large amount of uranium deposits (occurrences) have been discovered in recent decades. Previous studies have found that uranium deposits and coal seam have a certain correlation in their genesis and spatial distribution or sometimes uranium deposits develop directly in the coal seam. What are the geological characteristics of uranium enrichment? How is uranium enriched? How to strengthen the cooperative development of uranium and coal and environmental protection? In order to explain the aforementioned questions, the characteristics of uranium deposits, rock minerals, and geochemical and metallogenic chronology are summarized herein, and the geological control mechanism of uranium enrichment in coal-bearing strata is discussed. It is found that uranium enrichment (including sandstone uranium deposits and coal uranium deposits) has multistage genetic characteristics and is mainly spread over the gentle slope of the southern margin of the Yili basin, with its host rock possibly being sandstone, coal, and sometimes even mudstone. The uranium concentration has a considerable correlation with the reductant, and the occurrence state of uranium has both inorganic and organic affinities. In addition, uranium enrichment is believed to be a comprehensive effect of high uranium source rocks, tectonic activity, sedimentary facies, hydrogeology conditions, paleoclimate, and reductant. The difference is that uranium enrichment in sandstone is often generated in a mud-sand-mud stratigraphic structure, while uranium enrichment in coal usually develops as coal-sand-mud. What is more, strengthening the study of physical and chemical properties of the host rock, strengthening the study of uranium occurrence state, and sharing geological data are important ways for the cooperative development of coal and uranium resources and environmental protection.

Occurrence and behaviour of uranium in the groundwater and potential health risk associated in semi-arid region of Punjab, India

Occurrence of uranium (U) in the groundwater of south-west Punjab is a matter of great concern due to the rise of contaminant levels at an alarming rate, its spatial and vertical variability and poor understanding of uranium mobility with depth. Present study has been conducted to investigate the vertical extent of contamination and geochemical factors controlling U mobilization in the groundwater of semi-arid Punjab. Out of total 140 samples collected and analyzed, 76% samples have uranium levels greater than the chemical toxicity limit of World Health Organization (WHO, 30 μg.L−1) and 34% samples have concentration higher than the radiological toxicity limit given by Atomic Energy Regulatory Board (AERB, 60 μg.L−1). Water at shallow depth (<60 m) is found to be more contaminated than water at deeper depth (>60 m) and concentration lies in the range of 4.26–318.03 μg.L−1. Spatial distribution graphs are used to identify the hotspots of contamination and concentration is higher in the flow direction of groundwater towards south-west. In both the aquifers, groundwater is alkaline and oxic in character with carbonate weathering as dominant hydrogeochemical process affecting chemical composition of water. Higher uranium concentration is seen in the oxidizing, alkaline and carbonate-rich water. Alkali earth metals (Na+ & K+) are also strongly correlated with the uranium in groundwater at both the levels. Use of environmental stable isotopes (δ18O & δ2H) shows the evaporation signature in both the aquifers. Health risk assessment is carried out and values higher than permissible limit give indication towards the health risk to the population exposed due to the consumption of uranium contaminated water from long time. This study provides a strong base for better understanding the source of uranium in the aquifer system of region and the results would be useful for further studies in quaternary alluvial aquifers of semi-arid regions.