An evaluation of health risk to the public as a consequence of in situ uranium mining in Wyoming, USA

Fissure channeling caused anomalous uranium concentration in groundwater downstream of a uranium mine tailings impoundment site

Widespread uranium mining resulted in large amounts of radioactive wastes. While impoundment has been commonly used to store U-laden wastes, information has been lacking on the secondary contamination potential. We conducted a field-scale study at a prototype uranium mine tailings impoundment site in China to understand the abnormally high concentrations (0.90-36.7 μg/L) of uranium recently observed in the downstream groundwater. Based on on-site hydrogeological measurements and modeling analysis, fracture channels were identified in the aquifer. To consider the fissure channeling flow in the solute transport modeling, a modified discrete-continuum coupled modeling approach was established, which considers the flow dynamics within both the matrix domain and the preferential flow through the main fractures. The model was not only able to simulate the observed uranium concentrations at various locations, but also to reveal the U release rate from the impoundment. Moreover, the contaminant transport modeling supported that the abnormal uranium concentrations were attributed to the channeling flow in the aquifer fractures, which was confirmed through geological analysis. In addition to valuable field data, this work offered an effective modeling approach for assessing contaminant transport through fissure channeling and the associated environmental impact of waste disposal facilities in complex hydrogeological settings.

Statistical Analysis of Radioactivity: Lamprecht Uranium Mine in Texas

ABSTRACT

The former Lamprecht uranium mine facility in Texas ceased operations well before the new millennium. However, decommissioning activities were never completed by the licensee. Consequently, a legal proceeding was authorized between state and licensee representatives. Meanwhile, state funds were used to hire an independent contractor to perform radiological surveys and assess the magnitude of residual radioactivity across the terrain at the site. The purpose of this study was to apply advanced spatial statistical methods to the survey data measured by contractors at the Lamprecht site to precisely predict remaining radioactive hotspot locations post soil remediation activities. To accomplish this, descriptive statistics such as Google maps and boxplots along with inferential spatial statistical techniques, e.g., kriging and semivariograms, were employed. R coding was also used throughout. Specifically, the descriptive statistical methods included geographical mapping of targeted areas at the site coupled with summary statistics. Inferentially, spatial analytical techniques were employed to pinpoint the locations of elevated radiation levels above regulatory limits. Our results suggest that fewer hotspots were identified after remediation activities were completed at the site. This study provides an additional analytical resource for the State of Texas regarding the release of this former in situ leach uranium mine site to landowners for unrestricted use.

Associations between urinary heavy metals and anxiety among adults in the National Health and Nutrition Examination Survey (NHANES), 2007-2012

BACKGROUND

Few studies have investigated the associations between heavy metals and anxiety. The purpose of this study was to examine the associations between single and combined exposure to heavy metals and anxiety.

METHODS

This study employed data from the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2012. Anxiety was assessed by patients self-reporting the number of anxious days per month. First, we evaluated the associations between 10 heavy metals single exposure and anxiety by multivariable logistic regression. We then selected 5 heavy metals (cadmium, antimony, cobalt, tungsten, and uranium) for further analysis by elastic net regression. Subsequently, principal component analysis (PCA), weighted quantile regression (WQS), and Bayesian kernel machine regression (BKMR) were utilized to evaluate the associations between 5 heavy metals co-exposure and anxiety.

RESULTS

This study included 4512 participants, among whom 1206 participants were in an anxiety state. Urinary cadmium and antimony were separately related to an increased risk of anxiety (p for trend <0.01 and < 0.01, respectively). In PCA analysis, PC1 was associated with an increased risk of anxiety (p for trend <0.001). In WQS analysis, the positive WQS index was substantially linked with the risk of anxiety (OR (95%CI): 1.23 (1.04,1.39)). In BKMR analysis, the overall effects of co-exposure to heavy metals were positively connected with anxiety.

CONCLUSION

Our study identified a positive correlation between individual exposure to cadmium and antimony and the risk of anxiety. Additionally, the co-exposure to cadmium, antimony, cobalt, tungsten, and uranium was associated with an increased risk of anxiety.

A comprehensive review of radioactive pollution treatment of uranium mill tailings

Natural uranium is a crucial resource for clean nuclear energy, which has brought significant economic and social benefits to humanity. However, the development and utilization of uranium resources have also resulted in the accumulation of vast amounts of uranium mill tailings (UMTs), which pose a potential threat to human health and the ecological environment. This paper reviews the research progress on UMTs treatment technologies, including cover disposal, solidification disposal, backfilling disposal, and bioremediation methods. It is found that cover disposal is a versatile method for the long-term management of UMTs, the engineering performance and durability of the cover system can be improved by choosing suitable stabilizers for the cover layer. Solidification disposal can convert UMTs into solid waste for permanent disposal, but it produces a large amount of waste and requires high operating costs; it is necessary to explore the effectiveness and efficiency of solidification disposal for UMTs, while minimizing the bad environmental impact. Backfilling disposal realizes the resource utilization of solid waste, but the high radon exhalation rate caused by the UMTs backfilling also needs to be considered. Bioremediation methods have low investment costs and are less likely to cause secondary pollution, but the remediation efficiency is low, it can be combined with other treatment technologies to remedy the defects of a single remediation method. The article concludes with key issues and corresponding suggestions for the current UMTs treatment methods, which can provide theoretical guidance and reference for further development and application of radioactive pollution treatment of UMTs.

Chuan Huang Fang combining reduced glutathione in treating acute kidney injury (grades 1–2) on chronic kidney disease (stages 2–4): A multicenter randomized controlled clinical trial

Lack of effective drugs for acute kidney injury (AKI) grades 1–2 is a crucial challenge in clinic. Our previously single-center clinical studies indicated Chuan Huang Fang (CHF) might have nephroprotection in AKI on chronic kidney disease (CKD) (A on C) patients by preventing oxidant damage and inhibiting inflammation. Reduced glutathione (RG) has recently been shown to increase the clinical effectiveness of high-flux hemodialysis among patients with severe AKI. In this multicenter randomized controlled clinical study, we designed a new protocol to assess the efficacy and safety of CHF combining RG in patients with A on C. We also explored therapeutic mechanisms from renal fibrosis biomarkers. 98 participants were randomly and equally divided into the RG and RG + CHF subgroups. The RG and RG + CHF groups received general treatments with RG and a combination of RG and CHF, respectively. The therapy lasted for 2 weeks. In this study, the primary assessment result was a difference in the slope of serum creatinine (Scr) over the course of 2 weeks. The secondary evaluation outcomes were alterations in blood urea nitrogen (BUN), uric acid (UA), estimated glomerular filtration rate (eGFR), urinary AKI biomarkers, renal fibrosis biomarkers (transforming growth factor-β₁ (TGF-β₁), connective tissue growth factor (CTGF)), and traditional Chinese medicine (TCM) symptoms. Furthermore, vital signs and adverse events (AEs) were observed. Both groups had a slower renal function decline after treatment than before treatment. Compared with RG group, more reductions of Scr, BUN, UA, and better improvement of eGFR were observed in RG + CHF group (p < 0.05). Additionally, the levels of urinary AKI biomarkers, renal fibrosis biomarkers, and TCM syndromes were decreased in RG + CHF group versus RG group (p < 0.05). No significant between-group differences were observed of AEs. We thus concluded this novel therapy of CHF combining RG might be a useful method for treating A on C patients.

Efficacy and Safety of Chuan Huang Fang Combining Reduced Glutathione in Treating Acute Kidney Injury (Grades 1-2) on Chronic Kidney Disease (Stages 2-4): Study Protocol for a Multicenter Randomized Controlled Clinical Trial

Background

Acute kidney injury (AKI) is a global public health challenge resulting in considerable morbidity and mortality. AKI on chronic kidney disease (CKD) (AKI on CKD, A on C) accounts for about a third of total AKI. For severe AKI grade 3, renal replacement therapy (RRT) should be implemented in time. However, the lack of recognized drug treatment method for AKI grades 1-2 is a crucial problem in clinic. Chuan Huang Fang (CHF) is a Chinese herbal formulation developed for the treatment of A on C from the Shanghai Municipal Hospital of Traditional Chinese Medicine. Our previous studies suggested that CHF might effectively protect renal functions of A on C patients. As a widely used antioxidant in clinic, reduced glutathione (RG) is reported to improve the clinical efficacy of high-flux hemodialysis (HFHD) in severe AKI patients recently. To address the crucial problem mentioned above, thus we design a new clinical protocol of CHF combining RG and try to evaluate the efficacy and safety of this protocol in treating patients diagnosed with CKD stages 2-4 complicated with AKI grades 1-2.

Methods

This is a multicenter randomized controlled clinical trial. We intend to enroll 162 participants, and these participants will be divided into the RG group, the CHF group, and the RG + CHF group randomly assigning 1 : 1 : 1 principle. The RG group will be general treatments combining RG, the CHF group will be general treatments combining CHF, and the RG + CHF group will be general treatments combining RG and CHF. The duration of treatment will last two weeks. The primary evaluation outcome will be the change in the slope of serum creatinine (Scr) over 2 weeks. Secondary evaluation outcomes include changes in blood urea nitrogen (BUN), estimated glomerular filtration rate (eGFR), urinary AKI biomarkers (neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18), gamma-glutamyl transpeptidase (γ-GT), etc.), traditional Chinese medicine (TCM) symptoms, inflammatory indicators, and oxidative stress indicators. Meanwhile, the vital sign indicators and adverse events (AEs) will be closely observed. These dates will be meticulously recorded and properly handled by investigators throughout the study. Discussion. This study will provide convictive research-derived data to evaluate clinical efficacy and safety of CHF combing RG for CKD stages 2-4 complicated with AKI grades 1-2 and provide an evidence-based recommendation for clinicians. The timely completion of this trial will provide a novel drug treatment method for A on C. This trial is registered with ChiCTR2100043311 and registered on February 9, 2021.

A critical review on the occurrence and distribution of the uranium- and thorium-decay nuclides and their effect on the quality of groundwater

This critical review presents the key factors that control the occurrence of natural elements from the uranium- and thorium-decay series, also known as naturally occurring radioactive materials (NORM), including uranium, radium, radon, lead, polonium, and their isotopes in groundwater resources. Given their toxicity and radiation, elevated levels of these nuclides in drinking water pose human health risks, and therefore understanding the occurrence, sources, and factors that control the mobilization of these nuclides from aquifer rocks is critical for better groundwater management and human health protection. The concentrations of these nuclides in groundwater are a function of the groundwater residence time relative to the decay rates of the nuclides, as well as the net balance between nuclides mobilization (dissolution, desorption, recoil) and retention (adsorption, precipitation). This paper explores the factors that control this balance, including the relationships between the elemental chemistry (e.g., solubility and speciation), lithological and hydrogeological factors, groundwater geochemistry (e.g., redox state, pH, ionic strength, ion-pairs availability), and their combined effects and interactions. The various chemical properties of each of the nuclides results in different likelihoods for co-occurrence. For example, the primordial ²³⁸U, ²²²Rn, and, in cases of high colloid concentrations also ²¹⁰Po, are all more likely to be found in oxic groundwater. In contrast, in reducing aquifers, Ra nuclides, ²¹⁰Pb, and in absence of high colloid concentrations, ²¹⁰Po, are more mobile and frequently occur in groundwater. In highly permeable sandstone aquifers that lack sufficient adsorption sites, Ra is often enriched, even in low salinity and oxic groundwater. This paper also highlights the isotope distributions, including those of relatively long-lived nuclides (²³⁸U/²³⁵U) with abundances that depend on geochemical conditions (e.g., fractionation induced from redox processes), as well as shorter-lived nuclides (²³⁴U/²³⁸U, ²²⁸Ra/²²⁶Ra, ²²⁴Ra/²²⁸Ra, ²¹⁰Pb/²²²Rn, ²¹⁰Po/²¹⁰Pb) that are strongly influenced by physical (recoil), lithological, and geochemical factors. Special attention is paid in evaluating the ability to use these isotope variations to elucidate the sources of these nuclides in groundwater, mechanisms of their mobilization from the rock matrix (e.g., recoil, ion-exchange), and retention into secondary mineral phases and ion-exchange sites.

Collaborative determination of trace element mass fractions and isotope ratios in AQUA-1 drinking water certified reference material

The Isotrace CNRS workgroup in collaboration with National Research Council of Canada has characterized a number of trace element mass fractions and isotope ratios currently not certified in AQUA-1 natural drinking water reference material (NRC Canada). This survey further expands the use of this material as a tool for environmental quality control, method validation, and method development tool for the international community. Simultaneously, the SLRS-6 river water was analyzed as quality control and also in order to compare both water characteristics, which were sampled in the same area but having undergone different treatment. Mass fractions for B, Cs, Li, Ga, Ge, Hf, Nb, P, Rb, Rh, Re, S, Sc, Se, Si, Sn, Th, Ti, Tl, W, Y, Zr, REEs, and six isotopic ratios are proposed for Sr and Pb. Measurements were mostly performed using ICP-MS with various calibration approaches. The results are reported as consensus or indicative values depending on the number of available datasets, with their associated uncertainties.

Prediction of Potential Offsite TEDE, Excess Cancer Risk, Dominant Exposure Pathways, and Activity Concentration for Hypothetical Onsite Soil Contamination at the Proposed Rooppur Nuclear Power Plant

This study evaluates the potential offsite radiological hazards by calculating total effective dose equivalent (TEDE) and excess cancer risk if onsite soil contamination occurs at the proposed Rooppur Nuclear Power Plant (RNPP) site, Bangladesh. The assessment has been performed assuming a hypothetical soil contamination associated with Fukushima Nuclear disaster with the help of the RESRAD (residual radioactivity) OFFSITE computer program developed by Argonne National Laboratory, U.S. Six radionuclides, namely, Cs-134, Cs-136, Cs-137, La-140, Sr-90, and Te-129m have been considered. The maximum TEDE has been found approximately 2.8 mSv/yr whereas the maximum total excess cancer risk shows a value of 3.25×10−3. The number of dominant exposure pathways, maximum contributor pathways, and duration of dominance of different nuclides have been identified. Ingestion of fish is identified as the principal pathway to both TEDE and excess cancer risk. Time variation of activity concentration and dose/source ratio have also been studied.

Absorption and interaction mechanisms of uranium & cadmium in purple sweet potato(Ipomoea batatas L.)

The purpose of this study was to reveal the absorption and interaction mechanisms of uranium (U) & cadmium (Cd) in corps. Purple sweet potato (Ipomoea batatas L.) was selected as the experimental material. The absorption behavior of U and Cd in this crop and the effects on mineral nutrition were analyzed in a pot experiment. The interactions between U and Cd in purple sweet potato were analyzed using UPLC-MS metabolome analysis. The pot experiment confirmed that the root tuber of the purple sweet potato had accumulated U (1.68-5.16 mg kg^-1) and Cd (0.78-2.02 mg kg^-1) and would pose a health risk if consumed. Both U and Cd significantly interfered with the mineral nutrient of the roots. Metabolomics revealed that a total of 4865 metabolites were identified in roots. 643 (419 up; 224 down), 526 (332 up; 194 down) and 634 (428 up; 214 down) different metabolites (DEMs) were identified in the U, Cd, and U + Cd exposure groups. Metabolic pathway analysis showed that U and Cd induced the expression of plant hormones (the first messengers) and cyclic nucleotides (cAMP and cGMP, second messengers) in cells and regulated the primary/secondary metabolism of roots to induce resistance to U and Cd toxicity.

INVESTIGATION AND ANALYSIS OF ENVIRONMENTAL RADIOACTIVITY LEVELS AT TYPICAL URANIUM MINES IN THE SOUTH OF CHINA

The environmental radioactivity levels of two typical uranium mines in the south of China were investigated and analysed. According to the characteristics of uranium mines, the relevant parameters, including the surface gamma ray dose rate, concentration of radon in the air and concentration of radionuclides in the soil and surface water, of two uranium mines were evaluated and analysed. The results show that residents in the mining area were exposed to average maximum annual effective doses of 1.69 and 1.58 mSv due to the inhalation of radon and its daughters, while the employees received 2.59 and 1.87 mSv, respectively. Residents in the mining area were exposed to average maximum annual effective doses of 0.77 and 0.69 mSv due to gamma ray, while the employees received 1.64 and 1.33 mSv, respectively.

Electrokinetic remediation of uranium(VI)-contaminated red soil using composite electrolyte of citric acid and ferric chloride

In the process of electrokinetic (EK) remediation of uranium-contaminated soil, the existence form of uranium in soil pore fluid will affect on its migration behavior. In this paper, a novel type of electrolyte (citric acid + ferric chloride, CA+ FeCl₃) has been investigated for the EK remediation of uranium-contaminated red soil. The effects of different electrolyte and the concentrations of FeCl₃ on migration behavior of U(VI) and environmental risks were investigated after EK remediation. The result showed that the optimum concentration was 0.1 mol/L CA mixed with 0.03 mol/L FeCl₃ in this study. At this time, the removal efficiency of uranium was about 61.55 ± 0.41%, and the cumulative energy consumption was 0.2559 kWh. Compared with deionized water and single CA, combined CA with FeCl₃ has the advantages of high removal efficiency, low leaching toxicity, and less damage to the soil after the electrokinetic remediation treatment.

Ultrafast Recovery of Uranium from Seawater by Bacillus velezensis Strain UUS-1 with Innate Anti-Biofouling Activity

Highly-efficient recovery of uranium from seawater is of great concern in the growing demand for nuclear energy. Bacteria are thought to be potential alternatives for uranium recovery. Herein, a Bacillus velezensis strain, UUS-1, with highly-efficient uranium immobilization capacity is isolated and is used in the recovery of uranium from seawater. The strain exhibits time-dependent uranium recovery capacity and only immobilizes uranium after growing for 12 h. The carboxyl group together with the amino group inside the bacterial cells, but not previously identified phosphate group, are essential for uranium immobilization. UUS-1 shows broad-spectrum antimicrobial activity by producing diverse antimicrobial metabolites, which endows the strain with innate resistance to the biofouling of marine microorganisms. Based on the dry weight of the initially used bacterial cultures, UUS-1 concentrates uranium by 6.26 × 105 times and reaches the high immobilization capacity of 9.46 ± 0.39 mg U g-1 bacterial cultures in real seawater within 48 h, which is the fastest uranium immobilization capacity observed from real seawater. Overall considering the ultrafast and highly-efficient uranium recovery capacity and the innate anti-biofouling activity, UUS-1 is a promising alternative for uranium recovery from seawater.

Aspergillus niger changes the chemical form of uranium to decrease its biotoxicity, restricts its movement in plant and increase the growth of Syngonium podophyllum

Aspergillus niger (A. niger) and Syngonium podophyllum (S. podophyllum) have been used for wastewater treatment, and have exhibited a promising application in recent years. To determine the effects of A. niger on uranium enrichment and uranium stress antagonism of S. podophyllum, the S. podophyllum-A. niger combined system was established, and hydroponic remediation experiments were carried out with uranium-containing wastewater. The results revealed that the bioaugmentation of A. niger could increase the biomass of S. podophyllum by 5-7%, reverse the process of U(VI) reduction induced by S. podophyllum, and increase the bioconcentration factor (BCF) and translocation factor (TF) of S. podophyllum to uranium by 35-41 and 0.01-0.06, respectively, thereby improving the reduction of uranium in wastewater. Moreover, A. niger could promote the cell wall immobilization and the subcellular compartmentalization of uranium in the root of S. podophyllum, reduce the phytotoxicity of uranium entering root cells, and inhibit the calcium efflux from root cells, thereby withdrawing the stress of uranium on S. podophyllum.

The application of illite supported nanoscale zero valent iron for the treatment of uranium contaminated groundwater

In this study, nanoscale zero valent iron I-NZVI was investigated as a remediation strategy for uranium contaminated groundwater from the former Cimarron Fuel Fabrication Site in Oklahoma, USA. The 1 L batch-treatment system was applied in the study. The result shows that 99.9% of uranium in groundwater was removed by I-NZVI within 2 h. Uranium concentration in the groundwater stayed around 27 μg/L, and there was no sign of uranium release into groundwater after seven days of reaction time. Meanwhile the release of iron was significantly decreased compared to NZVI which can reduce the treatment impact on the water environment. To study the influence of background pH of the treatment system on removal efficiency of uranium, the groundwater was adjusted from pH 2-10 before the addition of I-NZVI. The pH of the groundwater was from 2.1 to 10.7 after treatment. The removal efficiency of uranium achieved a maximum in neutral pH of groundwater. The desorption of uranium on the residual solid phase after treatment was investigated in order to discuss the stability of uranium on residual solids. After 2 h of leaching, 0.07% of the total uranium on residual solid phase was leached out in a HNO₃ leaching solution with a pH of 4.03. The concentration of uranium in the acid leachate was under 3.2 μg/L which is below the EPA's maximum contaminant level of 30 μg/L. Otherwise, the concentration of uranium was negligible in distilled water leaching solution (pH = 6.44) and NaOH leaching solution (pH = 8.52). A desorption study shows that an acceptable amount of uranium on the residuals can be released into water system under strong acid conditions in short terms. For long term disposal management of the residual solids, the leachate needs to be monitored and treated before discharge into a hazardous landfill or the water system. For the first time, I-NZVI was applied for the treatment of uranium contaminated groundwater. These results provide proof that I-NZVI has improved performance compared to NZVI and is a promising technology for the restoration of complex uranium contaminated water resources.