Evaluation of the JF5-based Aspergillus galactomannoprotein lateral flow device for diagnosing invasive aspergillosis in cancer patients.

PURPOSE: Cancer patients are at heightened risk for invasive aspergillosis (IA), a condition associated with elevated mortality risk. The JF5-based Aspergillus Galactomannoprotein Lateral Flow Device (AspLFD) offers rapid point-of-care testing (POCT) for IA. This study evaluated the diagnostic performance of AspLFD in cancer populations. METHODS: This retrospective study examined cancer patient bronchoalveolar lavage fluid (BALF) and serum samples collected between September 2021 and January 2023. Both AspLFD and galactomannan (GM) assays were conducted, and the results were analysed by two independent researchers. RESULTS: This study included 242 samples from 218 cancer patients, with 58 BALF and 184 serum samples. The overall agreement between AspLFD and GM assay results was 92.1%, with a kappa value of 0.552. AspLFD diagnosed proven/probable IA with a sensitivity and specificity of 91.7% and 95.3%, respectively, whereas GM exhibited sensitivity and specificity values of 83.3% and 93.7%, respectively. There were no statistical differences in the sensitivity and specificity between the two methods (P > 0.05). For serum analyses, AspLFD and GM exhibited similar sensitivity (66.7% vs. 66.7%, P > 0.05) and specificity (98.6% vs. 96.6%, P > 0.05) values. However, the sensitivity of the AspLFD was superior to the GM assay (100% vs. 88.9%) in BALF analyses but the difference was not statistically significant (P > 0.05), with no difference in specificity (83.7% vs. 83.7%, P > 0.05). In the solid-tumour cohort, both the AspLFD and GM assay exhibited high sensitivity (100% for both) and specificity (94.2% vs. 92.8%, P > 0.05). CONCLUSION: The AspLFD demonstrated good performance in diagnosing IA in cancer patients, especially those with solid tumours. The AspLFD is thus an alternative POCT, particularly when GM evaluations are not readily available.

Bacteremia Caused by Turicella otitidis in a Patient with Diffuse Large B-Cell Lymphoma.

BACKGROUND: Invasive Gram-positive bacilli infections are commonly encountered in immunocompromised patients. In this paper, we report a bacteremia caused by Turicella otitidis in a patient with diffuse large B-cell lymphoma. METHODS: Bacteria was identified by VITEK MALDI-TOF MS. Drug sensitivity was analyzed by disk diffusion method. RESULTS: MALDI-TOF MS data demonstrated that the infection bacteria was Turicella otitidis. Drug susceptibility data showed that Turicella otitidis was possibly sensitive to vancomycin, polymyxin B, and chloramphenicol. Body temperature of the patient dropped after administration of vancomycin. The data indicated that vancomycin could be used to treat the infections caused by Turicella otitidis. CONCLUSIONS: MALDI-TOF MS can be used for the rapid and accurate identification of Turicella otitidis. Vancomycin can be used to treat the infection caused by Turicella otitidis. This study may provide a reference for the diagnosis and treatment of Turicella otitidis.

Geochemical transfer of cadmium in river sediments near a lead-zinc smelter.

Cadmium (Cd) is a highly toxic element and non-essential to human. Herein, the source and fate of Cd were examined in a typical sediment profile from the North River, South China, which was affected by the massive Pb-Zn smelting activities for decades. An exceptionally high enrichment of Cd, 107-441 mg/kg, was observed across the whole profile. Approximately 50-75% of Cd was retained in the weak acid soluble fraction. Risk assessment based on geoaccumulation index (Igeo), potential ecological risk index (Eri), bioavailable metal index (BMI) and toxic risk index (TRI) further indicated an extremely strong degree of potential ecological pollution and high toxic risks. The mineralogical composition of particles from the sediment profile exhibited the presence of pyrite, magnetite, wurtzite and greenockite. This further confirmed that Cd was migrated from smelting slags to the North River basin and enriched in sediment profile. Sediment Cd speciation analysis also implied a possible transformation of Cd from metal oxides in smelting slags to adsorbed phases and carbonates, which enhances the bioavailability of Cd. The findings indicate proper countermeasures or remediation approaches should be promptly taken towards high ecological risks of Cd arising from the depth profile extending nearly 1 m, due to lead-zinc smelting related activities.

Persistent thallium contamination in river sediments, source apportionment and environmental implications.

The adverse impacts of detrimental thallium (Tl) contamination are of increasing concerns to sustainable development. Herein, the contents, distributions and sources of Tl and potential toxic elements (PTEs) (Pb, As, Cr, Cu, Ni, Co, Sb, Cd and U) were investigated in sediments collected in Gaofeng River, which has been contaminated by long-term mining activities, located in Yunfu City, Southern China. Results indicated that excessive Tl levels were found in sediments (1.80-16.70 mg/kg). Sequential extraction procedure indicated that despite a large amount of Tl entrapped in residual fraction, a significant level of Tl (0.28-2.34 mg/kg) still exhibited in geochemically labile fractions, which was easy for Tl mobilization and availability. Pb isotope tracing method further confirmed that the pyrite exploitations may be the prime contaminated contributor (47-76%) to these sediments. These findings highlight that it is essential to establish more effective measures for Tl contamination control and call for engineered remediation countermeasures towards polluted river sediments.

Effects and mechanisms of mineral amendment on thallium mobility in highly contaminated soils.

Thallium (Tl) is an extremely toxic element, whose toxicity is even higher than mercury, arsenic, and cadmium. It is of great significance to hinder the migration and transfer of Tl from soils to the plants. A synthetic mineral amendment (SMA), mainly composed of different silicates, was evaluated for its effects on the transformation and retention of Tl in two typical highly Tl-contaminated soils from Southwest China. The results indicated that the addition of mineral amendment increased the soil of the pH by 0.46-2.13 units and distinctly reduced the content of active thallium in the soils. The extent of Tl reduction was related to the morphological characteristics of the original soil In particular, the application of the mineral amendment transformed 25.8-52.5% of the active Tl fractions in the soils to the residual fraction at 60 d. Adding mineral amendment to the soils can provide conditions to facilitate Tl to enter the silicate crystal lattice. The results of XPS evidenced that the proportion of Tl(I) in the soil was greatly reduced after adding the mineral amendment.

High contamination risks of thallium and associated metal(loid)s in fluvial sediments from a steel-making area and implications for environmental management.

Thallium (Tl) is an uncommon toxic element, with an even greater toxicity than that of As, Hg and Cd. Steel-making industry has been identified as an emerging new significant source of Tl contamination in China. This paper presents a pilot investigation of the contamination and geochemical transfer of Tl and associated metal(loid)s in river sediments affected by long-term waste discharge from the steel-making industry. The results uncovered an overall Tl contamination (1.96 ±â€¯0.42 mg/kg) across a sediment profile of approximately 1.5 m in length, even 10 km downstream the steel plant. Highly elevated contents of Pb, Cu, Cd, Zn and Sb were found in the fluvial sediments, displaying strong positive correlations with Tl contents. Elevated levels of geochemically mobile Tl as well as Cd, Zn, Cu and Pb occurred in the fluvial sediments, signifying anthropogenic imprints from steel production activities at high temperature. Levels of contamination and ecological risk were calculated to be moderate to considerable for Tl, Cu, Zn and high to very high for Cd, Pb, Sb. The results highlight that there is a great challenge in view of potentially considerable Tl pollution due to continuous massive steel production in many other parts of China. It is high time to initiate process-based management of Tl contamination control for the ambient aquifer system in the steel-making area.

Fungal Infection Caused by Geotrichum capitatum in a Severe Aplastic Anemia Patient: a Case Report and Review of the Literature.

BACKGROUND: Invasive fungal infections often occur in immunocompromised patients. Here, we report an infection case caused by Geotrichum capitatum in a severe aplastic anemia patient. METHODS: Identification of the pathogenic bacteria was done by sequencing and mass spectrometric analysis. RESULTS: The fungal infection was isolated from blood cultures. The pathogenic bacteria were identified as Geotrichum capitatum. The infection was primarily cured by voriconazole and caspofungin monotherapy. However, the effect was not obvious. Then a combination of liposomal amphotericin B and caspofungin was used. Body temperature of the patient decreased, and clinical symptoms improved. CONCLUSIONS: Sequencing and mass spectrometric analysis could have a role for Geotrichum capitatum diagnosis. Curative effect of using a single antifungal drug was unsatisfactory. Using liposome amphotericin B combined with caspofungin might obtain certain curative effect. Early diagnosis and appropriate combined therapy were necessary to improve the outcome of patients with Geotrichum capitatum infection.

Unraveling seasonal shifts in microbial and geochemical mediated arsenic mobilization at the estuarine sediment-water interface under redox changes.

The mobilization of arsenic (As) at the sediment-water interface (SWI) is crucial for determining the accumulation of dissolved As to potentially toxic levels. However, the specific impacts of redox processes involving iron (Fe) and sulfur (S), as well as microbial activities occurring in sediments, on As mobilization at the marine SWI remain poorly understood. In this study, we investigated As mobilization at the SWI in the Changjiang Estuary during three different seasons with different benthic redox conditions. The preferential reduction of arsenate (As(V)) to arsenite (As(III)) and subsequent re-adsorption onto newly formed crystalline Fe oxides restricted As release in the As(V) reduction layer. Enhanced Fe(III) reduction in the Fe(III) reduction layer contributed to As release, while the presence of low As-high Fe-high SO42- levels resulted in As removal through adsorption onto pyrite in the sulfate reduction layer. Analysis of functional genes indicated that As(V) in sediments was released into porewater through the reductive dissolution of As(V)-bearing Fe(III) oxides by Geobacter species, followed by microbial reduction of the liberated As(V) to As(III) by microbes carrying the arrA gene. The dominant pathway governing As mobilization at the SWI in the Changjiang Estuary shifted from microbial reduction control during the hypoxic summer to Fe redox control during the aerobic autumn and winter. These findings provide valuable insights into the complex mechanisms driving As mobilization and highlight the importance of considering seasonal variations in understanding As dynamics at the marine SWI.

The effect of vine tea (Ampelopsis grossedentata) extract on fatigue alleviation via improving muscle mass.

ETHNOPHARMACOLOGICAL RELEVANCE: Vine Tea (VT, Ampelopsis grossedentata), boasts a venerable tradition in China, with a recorded consumption history exceeding 1200 years. Predominantly utilized by ethnic groups in southwest China, this herbal tea is celebrated for its multifaceted therapeutic attributes. Traditionally, VT has been employed to alleviate heat and remove toxins, exhibit anti-inflammatory properties, soothe sore throats, lower blood pressure, and fortify bones and muscles. In the realm of functional foods derived from plant resources, VT has garnered attention for its potential in crafting anti-fatigue beverages or foods, attributed to its promising efficacy and minimal side effects. Currently, in accordance with the Food Safety Standards set forth by the Monitoring and Evaluation Department of the National Health and Family Planning Commission in China, VT serves as a raw material in various beverages. AIM OF THE STUDY: VT has an anti-fatigue or similar effect in folk. However, the underlying molecular mechanisms contributing to VT's anti-fatigue effects remain elusive. This study endeavors to investigate the influence of Vine Tea Aqueous Extract (VTE) on fatigue mitigation and to elucidate its operative mechanisms, with the objective of developing VTE as a functional beverage. MATERIALS AND METHODS: The preparation of VTE involved heat extraction and freeze-drying processes, followed by the identification of its metabolites using UPLC-QTOF-MS to ascertain the chemical composition of VTE. A fatigue model was established using a forced swimming test in mice. Potential molecular targets were identified through network pharmacology, transcriptome analysis, and molecular docking. Furthermore, RT-PCR and Western blot techniques were employed to assess mRNA and protein expressions related to the AMPK and FoxO pathways. RESULTS: VTE significantly prolonged the duration of swimming time in an exhaustive swimming test in a dose-dependent manner, while simultaneously reducing the concentrations of blood lactic acid (LA), lactate dehydrogenase (LDH), serum urea nitrogen (SUN), and creatine kinase (CK). Notably, the performance of the high-dose VTE group surpassed that of the well-recognized ginsenoside. VTE demonstrated a regulatory effect akin to ginsenoside on the AMPK energy metabolism pathway and induced downregulation in the expression of Gadd45α, Cdkn1a, FOXO1, and Fbxo32 genes, suggesting an enhancement in skeletal muscle mass. These findings indicate that VTE can improve energy metabolism and muscle mass concurrently. CONCLUSIONS: VTE exhibits significant anti-fatigue effects, and its mechanism is intricately linked to the modulation of the AMPK and FoxO pathways. Crucially, no caffeine or other addictive substances with known side effects were detected in VTE. Consequently, vine tea shows substantial promise as a natural resource for the development of anti-fatigue beverages within the food industry.

Microbial features with uranium pollution in artificial reservoir sediments at different depths under drought stress.

The uranium (U) containing leachate from uranium tailings dam into the natural settings, may greatly affect the downstream environment. To reveal such relationship between uranium contamination and microbial communities in the most affected downstream environment under drought stress, a 180 cm downstream artificial reservoir depth sediment profile was collected, and the microbial communities and related genes were analyzed by 16S rDNA and metagenomics. Besides, the sequential extraction scheme was employed to shed light on the distinct role of U geochemical speciations in shaping microbial community structures. The results showed that U content ranged from 28.1 to 70.1 mg/kg, with an average content of 44.9 mg/kg, significantly exceeding the value of background sediments. Further, U in all the studied sediments was related to remarkably high portions of mobile fractions, and U was likely deposited layer by layer depending on the discharge/leachate inputs from uranium-involving anthoropogenic facilities/activities upstream. The nexus between U speciation, physico-chemical indicators and microbial composition showed that Fe, S, and N metabolism played a vital role in microbial adaptation to U-enriched environment; meanwhile, the fraction of Ureducible and the Fe and S contents had the most significant effects on microbial community composition in the sediments under drought stress.

Exposure to loneliness cues reduces prosocial behavior: Evidence from N400 and P300.

Loneliness is a major risk factor for morbidity and mortality. However, the effect of loneliness on subsequent prosocial behavior is not well known. Understanding the neurobiological mechanisms underlying loneliness is necessary to address this research gap. We investigate the mechanism using a modified public goods game (PGG) wherein participants can choose to act for a collective or selfish interest after being exposed to loneliness cues. Both behavioral (Study 1) and event-related potential (ERP) (Study 2) measures were used to explore this relationship. In Study 1 (N = 131), we found that participants exhibited decreased prosocial actions under the loneliness priming condition as opposed to the control condition. In Study 2 (N = 17), frontal N400 and posterior P300 components were identified under the loneliness priming condition as opposed to the control condition. Increased (decreased) frontal N400 and posterior P300 lead to selfish (prosocial) choices. These results indicate that humans instinctively perceive loneliness as inconsistency with their desired social-relational life, which in turn stimulates coping strategies for self-preservation. This study contributes to our understanding of the neurobiological basis of loneliness associated with prosocial behavior.

Planet earth calling: unveiling the brain's response to awe and driving eco-friendly consumption.

Eco-friendly consumption is important for solving climate crisis and moving humanity toward a better future. However, few consumers are willing to pay premiums for eco-friendly products. We investigated the psychological and neural factors that can increase eco-friendly consumption. We propose an experience of awe, in which the individual self is temporarily attenuated as the importance of beings other than oneself increases. Behavioral (Study 1) and functional magnetic resonance imaging (fMRI; Study 2) experiments were conducted to explore the awe mechanisms through which climate crisis messages lead to eco-friendly consumption. In Study 1, we found participants felt awe when exposed to climate crisis messages, and their choice of eco-friendly consumption increased. In Study 2, we found that when individuals were exposed to messages depicting the climate crisis (as opposed to a control stimulus), their brains exhibited a lower level of activation in the self-awareness processing and a higher level of activation in external attention processing areas. These results suggest that the awe experience plays an important role in promoting eco-friendly consumption. Marketing must evolve from satisfying basic individual needs to a high level for the well-being of humanity, the planet, and the biosphere. This study sheds light on our understanding of human perceptions of the climate crisis and suggests an effective communication strategy to increase individuals' eco-friendly actions.

Insights into mucoid Acinetobacter baumannii: A review of microbiological characteristics, virulence, and pathogenic mechanisms in a threatening nosocomial pathogen.

Acinetobacter baumannii (A. baumannii) is an opportunistic pathogen and leading cause of health care-associated infections. Several known pathogenic factors, including lipopolysaccharide, capsular polysaccharides, phospholipase, protein secretion systems, two component efflux pumps and biofilm formation, are associated with the bacteria. However, owing to the new biological characteristics rapidly developed under the external stress, the pathogenesis becomes complicated. The formation of mucoid phenotype is a major adaptive defense response for A. baumannii. The mucus is mainly comprised of capsular polysaccharide, which forms a barrier around the bacterial cell wall, and provides protection from environmental pressures and host immune responses. Importantly, mucoid formation has been shown to confer changes in the pathogenicity and pathogenesis of A. baumannii. Thus, this review aims to highlight the biological characteristics, virulence and underlying pathogenic mechanisms of mucoid A. baumannii. We primarily provide profound insight into the structure, function and detecting methods of the mucus in mucoid A. baumannii. Then we mainly illustrate the current studies on mucoid A. baumannii. Finally, the unsolved areas associated with mucoid A. baumannii are summarized. In summary, this review will critically offer a comprehensive understanding of mucoid A. baumannii and provide novel insight into the diagnosis and intervention strategies for the increasingly deadly human pathogen.

Microbial response and adaption to thallium contamination in soil profiles.

Thallium (Tl) is a trace metal with high toxicity. Comprehensive investigation of spatial distribution of Tl and microorganism is still limited in soils from mining area. In this study, 16S rRNA sequencing and network analysis were used for deciphering the co-occurrence patterns of bacterial communities in two different types of soil profiles around a typical Tl-bearing pyrite mine. The results showed that geochemical parameters (such as pH, S, Tl, Fe and TOM) were the driving forces for shaping the vertical distribution of microbial community. According to network analysis, a wide diversity of microbial modules were present in both soil profiles and affected by depth, significantly associated with variations in Tl geochemical fractionation. Phylogenetic information further unveiled that the microbial modules were mainly dominated by Fe reducing bacteria (FeRB), Fe oxidizing bacteria (FeOB), S oxidizing bacteria and Mn reducing bacteria. The results of metagenome indicated that Fe, Mn and S cycle in soil are closely involved in the biogeochemical cycle of Tl. The findings of co-occurrence patterns in the bacterial network and correlation between microorganisms and different geochemical fractions of Tl may benefit the strategy of bioremediation of Tl-contaminated soils with indigenous microbes.

Dynamics of arsenic and its interaction with Fe and S at the sediment-water interface of the seasonal hypoxic Changjiang Estuary.

The dynamics of As at the sediment-water interface (SWI) is an important link in driving As release into the upper water column to affect biological activities. At present, it is unclear about the As cycling at the SWI, especially under the influence of seasonal hypoxia in the Changjiang Estuary. In this study, the profile variations of As in porewater and solid phases from the Changjiang Estuary were studied. Results suggested that As profiles presented the "removal-release-removal" pattern with depth. Arsenic profiles were typically characterized by subsurface maxima in porewater and surficial enrichment in solid phase, which were closely related to Fe and S cycling. The occurrence of porewater As peaks and its obvious speciation transition at subsurface layers, companied by the conversion of dominant phases of solid As from reductive to oxidative fractions at the same layers indicated the reductive release of As at redoxcline. Arsenic species, saturation indexes (SI) and net reaction rates (RnetAs) suggested that the removal of As at surface and deep layers were attributed to the adsorption of As(V) by Fe oxides and the formation of orpiment and/or adsorption by Fe sulfides, respectively. The benthic hypoxic environment in late-summer was more favorable for upward migration and diffusion of As. This process was considered as an important contribution to the elevated aquatic As in the Changjiang Estuary.

[Response of Bacteriohopanepolyols to Hypoxic Conditions in the Surface Sediments of the Yangtze Estuary and Its Adjacent Areas].

Bacteriohopanepolyols (BHPs), as a novel bacterial biomarker, show clear potential for tracking organic matter sources and environmental change. To evaluate BHPs as indicators of seasonal hypoxia in the Yangtze Estuary and its adjacent areas, the composition, distribution, and source of BHPs in surface sediments were analyzed using high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (HPLC-APCI-MS). A total of 12 BHPs were detected with a normalized TOC concentration of 3.79-269 µg·g-1. The BHPs present in the surface sediments were dominated by bacteriohopanetetrol (BHT), 2-methyl-BHT, amino-BHPs, and adenosylhopane and its homologues, accounting for 40%, 22%, 12%, and 4% of the total BHPs, respectively. Each of these components and their corresponding indices show clear spatial trends. Specifically, BHT showed an "offshore increase" trend, which was mainly attributed to marine autochthonous inputs; and soil marker BHPs including adenosylhopane, which were dominated by terrestrial sources, showed an "offshore decrease" trend. The Rsoil index indicated a similar spatial pattern to the soil marker BHPs, with the relative contribution of terrestrial organic matter decreasing from 61.5% in coastal waters to 1.66% in the open ocean. This suggests that the organic matter in the coastal waters was mainly derived from terrestrial sources while marine sources were dominant in the open ocean. BHT-Ⅱ, the BHT stereoisomer, was derived from anaerobic ammonium oxidizing bacteria. High BHT-Ⅱ ratios were consistent with seasonal hypoxic zones in the Yangtze Estuary and, furthermore, these ratios were significantly negatively correlated with dissolved oxygen (DO) concentrations in the bottom waters. These observations indicate that hypoxic environments are beneficial to BHT-Ⅱ production, implying that BHT-Ⅱ can be used as an indicator of marine hypoxia.

Acquired mucoid phenotype of Acinetobacter baumannii: Impact for the molecular characteristics and virulence.

Mucoid phenotype is an important adaptive defense response for Acinetobacter baumannii (A. baumannii). The aim of this study was to analyze the impact of mucoid phenotype for the molecular characteristics and virulence of A. baumannii. We observed that the colonies of mucoid A. baumannii were moist, with an elevated surface, and the wire drawing result was positive. Transmission electron microscopy data showed that the outer wall of the mucoid colonies was not smooth, had protruding pseudopodia, and was surrounded by a layer of unknown material. Antibiotic susceptibility testing showed that the mucoid strains were multidrug resistant. Notably, the mucoid phenotype and antibiotic resistance were not correlated with the amount of biofilm produced by A. baumannii. MLST data demonstrated that the mucoid A. baumannii strains belonged to type ST2. Most (82.6 %, 38/46) of the multidrug-resistant nonmucoid strains also belonged to the molecular type ST2 and to other types, including ST129, ST158, ST195, ST80 and ST3. Moreover, mucoid A. baumannii strains were more virulent than nonmucoid isolates in a mouse model. The comparative transcriptomic data indicated that 15 genes, especially IX87_RS16955 (acnA), IX87_RS10800 (XanP), IX87_RS12875 (GlmM), IX87_RS00885 and IX87_RS12395 (bfr), were possibly associated with the phenotype and virulence of mucoid A. baumannii. In conclusions, the study comprehensively describes the molecular characteristics and virulence regulatory mechanism of mucoid A. baumannii, and provides novel insights for the prevention and treatment of infections associated with these strains.

Cadmium isotopic fractionation in lead-zinc smelting process and signatures in fluvial sediments.

Cadmium (Cd) is a toxic heavy metal pollutant. Various industrial activities, especially metal smelting, are the main sources of Cd pollution. Cd isotopes have exhibited the ability to be excellent source tracers and can be used to assess the pollution contributions from different sources. Herein, in a typical lead-zinc smelter, Shaoguan, China, significant Cd isotopic fractionation was found during the high temperature smelting process and followed a Rayleigh distillation model. The heavier Cd isotopes were concentrated in the slag, while the lighter Cd isotopes were concentrated in the dust. In the downstream sediment profile of the smelter, sediments have extremely high Cd concentrations that far exceed the Chinese background sediment, indicating severe pollution levels. The ε114/110Cd of the sediment core, ranged from - 0.62 ± 0.5-1.73 ± 0.5, are found between slag (ε114/110Cd=10.42) and dust (ε114/110Cd=-5.68). The binary mixture model suggests that 88-93% of the Cd in sediment profile was derived from the slag, and 7-12% from the deposition of dust. The findings demonstrate the great potential to apply Cd isotopes as a new geochemical tool to distinguish anthropogenic sources and quantify the contribution from various sources in the environment.

Uranium re-adsorption on uranium mill tailings and environmental implications.

Uranium mill tailings (UMTs) are one critical source of environmental U pollution. Leaching test has been extensively used to reveal U release capacity and mechanism from UMTs, while little attention has been paid to the effects of re-adsorption process on U release. In this study, the role of U re-adsorption behaviors during leaching test with UMTs was comprehensively investigated. Through paired data on mineralogical composition and aqueous U speciation, the influence of environmentally relevant factors on U re-absorption capacity and mechanism on UMTs with different particle sizes was revealed. Significant amounts of U re-adsorption were observed and primarily attributed to the adsorption on chlorite, albite and muscovite as well as combined reduction-sequestration by muscovite. Uranium re-adsorption predominantly occurred via inner-sphere complexation and surface precipitation depending on leachant pH. Coexisting sulfate or phosphate could further enhance U re-adsorption. The enhanced re-adsorption from sulfate occurred when inner-sphere complexation governed the re-adsorption process. These findings suggest that the environmental hazards and ecological risks of the U containing (waste) solids might have been underestimated due to the ignorance of the re-adsorption process, since the re-adsorbed U could be easily re-mobilized. The insights from this study are also helpful in developing effective in-situ remediation strategies.

Geochemical and U-Th isotopic insights on uranium enrichment in reservoir sediments.

Uranium (U) geochemistry and its isotopic compositions of reservoir sediments in U mine area were poorly understood. Herein, U and Th isotopic compositions were employed to investigate source apportionment and geochemical behavior of U in 41 reservoir sediments from a U mining area, Guangdong, China. The remarkably high contents of both total U (207.3-1117.7 mg/kg) and acid-leachable U (90.3-638.5 mg/kg) in the sediments exhibit a severe U contamination and mobilization-release risk. The U/Th activity ratios (ARs) indicate that all sediments have been contaminated apparently by U as a result of discharge of U containing wastewater, especially uranium mill tailings (UMT) leachate, while the variations of U/Th ARs are dominated by U geochemical behaviors (mainly redox process and adsorption). The U isotopic compositions (δ238U) showed a large variance through the sediment profile, varying from - 0.62 to - 0.04‰. The relation between δ238U and acid-leachable U fraction demonstrates that the U isotopic fractionation in sediments can be controlled by bedrock weathering (natural activity), UMT leachate (anthropogenic activity) and subsequent biogeochemical processes. The findings suggest that U-Th isotopes are a powerful tool to better understand U geochemical processes and enrichment mechanism in sediments that were affected by combined sources and driving forces.