Efficient removal of As(III) from groundwaters through self-alkalization in an asymmetric flow-electrode electrochemical separation system

It remains a great challenge to efficiently remove As(III) from groundwater using traditional technologies due to its stable electroneutral form. This study constructed an asymmetric flow-electrode electrochemical separation (AFES) system, which overcomes the drawback of H+ release from anodic carbon oxidation and achieves continuous self-alkalization function and highly efficient removal of As(III) from groundwater. At the applied voltage of 1.2 V and initial pH 7.5, the system could rapidly decrease the total As (T-As) concentration from 150.0 to 8.9 μg L-1 within 90 min, with an energy consumption of 0.04 kWh m-3. The self-alkalization was triggered by the generation of H2O2 from dissolved oxygen reduction and the adsorption of H+ on the cathode in the feed chamber, which significantly promoted the dissociation and oxidation of As(III), resulting in the removal of T-As predominantly in the form of As(V). The removal performance of T-As was slightly affected by the initial pH and coexisting ions in the feed chamber. The AFES system also exhibited considerable stability after 20 cycles of continuous experiments and superior performance in treating As-containing real groundwater. Moreover, the pH of the alkalized solution can be restored to the initial level by standing or aeration operation. This work offers a novel and efficient pathway for the detoxication of As(III)-contaminated groundwaters.

Glutathione Might Attenuate Arsenic-Induced Liver Injury by Modulating the Foxa2-XIAP Axis to Reduce Oxidative Stress and Mitochondrial Apoptosis

Arsenic (AS) is a metalloid element that widely exists and can cause different degrees of liver damage. The molecular mechanism of arsenic-induced liver injury has yet to be fully elucidated. Clinically, glutathione (GSH) is often used as an antidote for heavy metal poisoning and hepatoprotective drugs. However, the hepatoprotective effect of glutathione remains unknown in arsenic-induced liver injury. The regulatory relationship between Foxa2 and XIAP may play an important role in mitochondrial survival and death. Therefore, we took Foxa2-XIAP as the axis to explore the protective mechanism of GSH. In this study, we first established a mouse model of chronic arsenic exposure and examined liver function as reflected by quantitative parameters such as aspartate aminotransferase and alanine aminotransferase. Also, redox parameters in the liver were measured, including malondialdehyde, superoxide dismutase, 8-hydroxy-2'-deoxyguanosin, and glutathione peroxidase. RT-qPCR and western-blotting were used to detect the levels of related genes and proteins, such as Foxa2, XIAP, Smac, Bax, Bcl2, Caspase9, and Caspase3. Subsequently, GSH was administered at the same time as high arsenic exposure, and changes in the above parameters were observed. After a comprehensive analysis of the above results, we demonstrate that GSH treatment alleviates arsenic-induced oxidative stress and inhibits the mitochondrial pathway of apoptosis, which can be regulated through the Foxa2 and XIAP axis. The present study would be helpful in elucidating the molecular mechanism of arsenic-induced liver injury and identifying a new potential therapeutic target. And we also provided new theoretical support for glutathione in the treatment of liver damage caused by arsenic.

An impressive pristine biochar from food waste digestate for arsenic(V) removal from water: Performance, optimization, and mechanism

Anaerobic digestion has become a global practice for valorizing food waste, but the recycling of the digestate (FWD) remains challenging. This study aimed to address this issue by utilizing FWD as a low-cost feedstock for Ca-rich biochar production. The results demonstrated that biochar pyrolyzed at 900 °C exhibited impressive As(V) adsorption performance without any modifications. Kinetic analysis suggested As(V) was chemisorbed onto CDBC9, while isotherm data conformed well to Langmuir model, indicating monolayer adsorption with a maximum capacity of 76.764 mg/g. Further analysis using response surface methodology revealed that pH value and adsorbent dosage were significant influencing factors, and density functional theory (DFT) calculation visualized the formation of ionic bonds between HAsO42- and CaO(110) and Ca(OH)2(101) surfaces. This work demonstrated the potential of using FWD for producing Ca-rich biochar, providing an effective solution for As(V) removal and highlighting the importance of waste material utilization in sustainable environmental remediation.

Reduced Peripheral Blood Mitochondrial DNA Copy Number as Identification Biomarker of Suspected Arsenic-Induced Liver Damage

Arsenic (As) can cause liver damage and liver cancer and is capable of seriously affecting human health. Therefore, it is important to identify biomarkers of arsenic-induced liver damage. Mitochondria are key targets of hepatotoxicity caused by arsenic. The mitochondrial DNA copy number (mtDNAcn) is the number of mitochondrial DNA (mtDNA) copies in the genome. mtDNA is vulnerable to exogenous chemical attacks, thus causing mtDNAcn to change after exposure to environmental pollutants. Therefore, mtDNAcn can serve as a potential marker to identify and assess the risk of diseases caused by exposure to environmental pollutants. In this study, we selected 272 arsenicosis patients (155 cases without liver damage and 117 cases with liver damage) and 218 participants not exposed to arsenic (155 cases without liver damage and 63 cases with liver damage) as subjects to investigate the correlation between peripheral blood mtDNAcn and arsenic-induced liver damage, as well as the ability of peripheral blood mtDNAcn to identify and assess the risk of arsenic-induced liver damage. Peripheral blood mtDNAcn in patients with arsenic-induced liver damage is significantly decreased and negatively correlated with serum ALT, AST, and GGT levels. The decrease of peripheral blood mtDNAcn was associated with an increased risk of arsenic-induced liver damage. The receiver operating characteristic (ROC) curve analysis indicated that peripheral blood mtDNAcn could specifically identify patients with liver damage in the arsenicosis group. The decision tree C5.0 model was established to identify arsenicosis in all patients with liver damage. Peripheral blood mtDNAcn was included in the model and played the most important role in the identification of arsenic-induced liver damage. This study provided a basis for the identification and evaluation of arsenic-induced liver damage by peripheral blood mtDNAcn, indicating that peripheral blood mtDNAcn is expected to be a potential biomarker of arsenic-induced liver damage, and provides clues for exploring the mechanism of arsenic-induced liver damage from mitochondria damage.

Sulfurization alters phenol-formaldehyde resin microplastics redox property and their efficiency in mediating arsenite oxidation

Microplastics weathering by various types of oxidants in the oxic environment and their interaction with environmental contaminants have drawn numerous scientific attention. However, the environmental fate of microplastics under a reducing environment has been largely unresolved. Herein, the change of physicochemical and redox properties of microplastics during the weathering under a sulfate-reducing environment and the interaction with arsenite were addressed. The sulfurization of phenol-formaldehyde resin microplastics under a sulfate-reducing environment generated smooth and porous particles with the induction of organic S species. Multiple spectroscopic results demonstrated thioether and thiophene groups formed by the substitute removal of O-containing functional groups. Moreover, the sulfurization process induced the reduction of carbonyl groups and oxidation of phenolic hydroxyl groups and resulted in the formation of semiquinone radicals. The O-containing functional groups contributed to microplastics redox property and As(III) oxidation while S-containing functional groups showed no obvious effect. The sulfurized microplastics had lower efficiency in mediating arsenite oxidation than the unsulfurized counterparts due to the decreased electron donating capacity. Producing hydrogen peroxides by electron-donating phenol groups and semiquinone radicals and the direct semiquinone radicals oxidation could mediate arsenite oxidation. The findings of this study help us understand the fate of microplastics in redox fluctuation interfaces.

Mechanisms of genotoxicity and proteotoxicity induced by the metalloids arsenic and antimony

Arsenic and antimony are metalloids with profound effects on biological systems and human health. Both elements are toxic to cells and organisms, and exposure is associated with several pathological conditions including cancer and neurodegenerative disorders. At the same time, arsenic- and antimony-containing compounds are used in the treatment of multiple diseases. Although these metalloids can both cause and cure disease, their modes of molecular action are incompletely understood. The past decades have seen major advances in our understanding of arsenic and antimony toxicity, emphasizing genotoxicity and proteotoxicity as key contributors to pathogenesis. In this review, we highlight mechanisms by which arsenic and antimony cause toxicity, focusing on their genotoxic and proteotoxic effects. The mechanisms used by cells to maintain proteostasis during metalloid exposure are also described. Furthermore, we address how metalloid-induced proteotoxicity may promote neurodegenerative disease and how genotoxicity and proteotoxicity may be interrelated and together contribute to proteinopathies. A deeper understanding of cellular toxicity and response mechanisms and their links to pathogenesis may promote the development of strategies for both disease prevention and treatment.

Reductive stress induced by NRF2/G6PD through glucose metabolic reprogramming promotes malignant transformation in Arsenite-exposed human keratinocytes

Our previous research found that the nuclear factor-E2-related factor 2 (NRF2) protein was sustained activated in malignant transformation of human keratinocyte (HaCaT cells) caused by NaAsO2, but the role of NRF2 in it remains unknown. In this study, malignant transformation of HaCaT cells and labeled HaCaT cells used to detect mitochondrial glutathione levels (Mito-Grx1-roGFP2 HaCaT cells) were induced by 1.0 μM NaAsO2. Redox levels were measured at passages 0, early stage (passages 1, 7, 14), later stage (passages 21, 28 and 35) of arsenite-treated HaCaT cells. Oxidative stress levels increased at early stage. The NRF2 pathway was sustained activated. Cells and mitochondrial reductive stress levels (GSH/GSSG and NADPH/NADP+) increased. The mitochondrial GSH/GSSG levels of Mito-Grx1-roGFP2 HaCaT cells also increased. The indicators of glucose metabolism glucose-6-phosphate, lactate and the glucose-6-phosphate dehydrogenase (G6PD) levels increased, however Acetyl-CoA level decreased. Expression levels of glucose metabolic enzymes increased. After transfection with NRF2 siRNA, the indicators of glucose metabolism were reversed. After transfection with NRF2 or G6PD siRNA, cells and mitochondrial reductive stress levels decreased and the malignant phenotype was reversed. In conclusion, oxidative stress occurred in the early stage and the NRF2 was sustained high expression. In the later stage, increased NRF2/G6PD through glucose metabolic reprogramming induced reductive stress, thereby leading to malignant transformation.

Mechanistic Insights into Effects of Different Dietary Polyphenol Supplements on Arsenic Bioavailability, Biotransformation, and Toxicity Based on a Mouse Model

Arsenic (As) exposure has been related to many diseases, including cancers. Given the antioxidant and anti-inflammatory properties, the dietary supplementation of polyphenols may alleviate As toxicity. Based on a mouse bioassay, this study investigated the effects of chlorogenic acid (CA), quercetin (QC), tannic acid (TA), resveratrol (Res), and epigallocatechin gallate (EGCG) on As bioavailability, biotransformation, and toxicity. Intake of CA, QC, and EGCG significantly (p < 0.05) increased total As concentrations in liver (0.48-0.58 vs 0.27 mg kg-1) and kidneys (0.72-0.93 vs 0.59 mg kg-1) compared to control mice. Upregulated intestinal expression of phosphate transporters with QC and EGCG and proliferation of Lactobacillus in the gut of mice treated with CA and QC were observed, facilitating iAsV absorption via phosphate transporters and intestinal As solubility via organic acid metabolites. Although As bioavailability was elevated, serum levels of alpha fetoprotein and carcinoembryonic antigen of mice treated with all five polyphenols were reduced by 13.1-16.1% and 9.83-17.5%, suggesting reduced cancer risk. This was mainly due to higher DMAV (52.1-67.6% vs 31.4%) and lower iAsV contribution (4.95-10.7% vs 27.9%) in liver of mice treated with polyphenols. This study helps us develop dietary strategies to lower As toxicity.

Molecular-scale characterization of groundwater treatment sludge from around the world: Implications for potential arsenic recovery

Iron (Fe)-based treatment methods are widely applied to remove carcinogenic arsenic (As) from drinking water, but generate toxic As-laden Fe (oxyhydr)oxide waste that has traditionally been ignored for resource recovery by the water sector. However, the European Commission recently classified As as a Critical Raw Material (CRM), thus providing new incentives to re-think As-laden groundwater treatment sludge. Before As recovery techniques can be developed for groundwater treatment waste, detailed information on its structure and composition is essential. To this end, we comprehensively characterized sludge generated from a variety of As-rich groundwater treatment plants in different geographic regions by combining a suite of macroscopic measurements, such as total digestions, leaching tests and BET surface area with molecular-scale solid-phase analysis by Fe and As K-edge X-ray absorption spectroscopy (XAS). We found that the As mass fraction of all samples ranged from ∼200-1200 mg As/kg (dry weight) and the phosphorous (P) content reached ∼0.5-2 mass%. Notably, our results indicated that the influent As level was a poor predictor of the As sludge content, with the highest As mass fractions (940-1200 mg As/kg) measured in sludge generated from treating low groundwater As levels (1.1-22 µg/L). The Fe K-edge XAS data revealed that all samples consisted of nanoscale Fe(III) precipitates with less structural order than ferrihydrite, which is consistent with their high BET surface area (up to >250 m2/g) and large As and P mass fractions. The As K-edge XAS data indicated As was present in all samples predominantly as As(V) bound to Fe(III) precipitates in the binuclear-corner sharing (2C) geometry. Overall, the similar structure and composition of all samples implies that As recovery methods optimized for one type of Fe-based treatment sludge can be applied to many groundwater treatment sludges. Our work provides a critical foundation for further research to develop resource recovery methods for As-rich waste.

Arsenic transformation and redistribution in groundwater induced by the complex geochemical cycling of iron and sulfur

Iron (hydr)oxides are effective sorbents of arsenic that undergo reductive dissolution when exposed to dissolved sulfide, which significantly impacts the movement and repartition of arsenic in groundwater. This study investigated the sulfidation of As-bearing ferrihydrite and its consequences on arsenic repartitioning as well as formation and transformation of secondary minerals induced by sulfide in batch experiments. The sulfidation of As(III) and As(V) adsorbed on ferrihydrite shows very different results. In the As(V) system, sulfidation resulted in the production of significant amounts of elemental sulfur (S0) and Fe2+, and Fe2+ and sulfide combine to form mackinawite. Subsequently, Fe2+ adsorbed and catalyzed the conversion of residual ferrihydrite to lepidocrocite. However, in the As(III) system, As(III) was protonated in the presence of sulfide to produce thioarsenate, which accounted for 87.9 % of the total aqueous arsenic concentration. The formation of thioarsenate also consumed the S0 produced by the sulfidation, resulting in no detectable S0 during solid phase characterization. The adsorption of thioarsenate on iron minerals notably affected the surface charge density of ferrihydrite, hindering the further formation of secondary minerals. Studies on the influence of thiolation on As-Fe-S system are of great significance for understanding the migration and redistribution of arsenic in groundwater systems under sulfur-rich conditions.

Arsenic Removal Using Unconventional Material with Iron Content: Batch Adsorption and Column Study

The remediation of arsenic contamination in potable water is an important and urgent concern, necessitating immediate attention. With this objective in mind, the present study investigated arsenic removal from water using batch adsorption and fixed-bed column techniques. The material employed in this study was a waste product derived from the treatment of groundwater water for potable purposes, having a substantial iron composition. The material's properties were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier-transformed infrared spectroscopy (FT-IR). The point of zero charge (pHPZC) was measured, and the pore size and specific surface area were determined using the BET method. Under static conditions, kinetic, thermodynamic, and equilibrium studies were carried out to explore the influencing factors on the adsorption process, namely the pH, contact time, temperature, and initial arsenic concentration in the solution. It was found that the adsorption process is spontaneous, endothermic, and of a physical nature. In the batch adsorption studies, the maximum removal percentage was 80.4% after 90 min, and in a dynamic regime in the fixed-bed column, the efficiency was 99.99% at a sludge:sand = 1:1 ratio for 380 min for a volume of water with arsenic of ~3000 mL. The kinetics of the adsorption process conformed to a pseudo-second-order model. In terms of the equilibrium studies, the Sips model yielded the most accurate representation of the data, revealing a maximum equilibrium capacity of 70.1 mg As(V)/g sludge. For the dynamic regime, the experimental data were fitted using the Bohart-Adams, Thomas, and Clark models, in order to establish the mechanism of the process. Additionally, desorption studies were conducted, serving as an essential step in validating the practical applicability of the adsorption process, specifically in relation to the reutilization of the adsorbent material.

Revealing the solid-solution interface interference behaviors between Cu2+ and As(III) via partial peak area analysis of simulations and experiments

The mutual interference in the sensing detection of heavy metal ions (HMIs) is considerably serious and complex. Besides, the co-existed ions may change the stripping peak intensity, shape and position of the target ion, which partly makes peak current analysis inaccurate. Herein, a promising approach of partial peak area analysis was proposed firstly to research the mutual interference. The interference between two species on their electrodeposition processes was investigated by simulating different kinetics parameters, including surface coverage, electro-adsorption, -desorption rate constant, etc. It was proved that the partial peak area is sensitive and regular to these interference kinetics parameters, which is favorable for distinctly identifying different interferences. Moreover, the applicability of the partial peak area analysis was verified on the experiments of Cu2+, As(III) interference at four sensing interfaces: glassy carbon electrode, gold electrode, Co3O4, and Fe2O3 nanoparticles modified electrodes. The interference behaviors between Cu2+ and As(III) relying on solid-solution interfaces were revealed and confirmed by physicochemical characterizations and kinetics simulations. This work proposes a new descriptor (partial peak area) to recognize the interference mechanism and provides a meaningful guidance for accurate detection of HMIs in actual water environment.

Contribution of molecular structures and quantum chemistry technique to root concentration factor: An innovative application of interpretable machine learning

Root concentration factor (RCF) is a significant parameter to characterize uptake and accumulation of hazardous organic contaminants (HOCs) by plant roots. However, complex interactions among chemicals, plant roots and soil make it challenging to identify underlying mechanisms of uptake and accumulation of HOCs. Here, nine machine learning techniques were applied to investigate major factors controlling RCF based on variable combinations of molecular descriptors (MD), MACCS fingerprints, quantum chemistry descriptors (QCD) and three physicochemical properties related to chemical-soil-plant system. Compared to models with variables including MACCS fingerprints or solitary physicochemical properties, the XGBoost-6 model developed by the variable combination of MD, QCD and three physicochemical properties achieved the most remarkable performance, with R2 of 0.977. Model interpretation achieved by permutation variable importance and partial dependence plots revealed the vital importance of HOCs lipophilicity, lipid content of plant roots, soil organic matter content, the overall deformability and the molecular dispersive ability of HOCs for regulating RCF. The integration of MD and QCD with physicochemical properties could improve our knowledge of underlying mechanisms regarding HOCs accumulation in plant roots from innovative structural perspectives. Multiple variables combination-oriented performance improvement of model can be extended to other parameters prediction in environmental risk assessment field.

Assessing the potential molecular mechanism of arsenite-induced skin cell senescence

Arsenic exposure is a public health concern worldwide. Skin damage, as a typical lesion of arsenic exposure, the mechanism is still unknown. Studies have found that cellular senescence plays a key role in arsenic-induced skin damage, and the previous research found that the ERK/CEBPB signaling pathway may be an important molecular event of arsenic-induced skin cell senescence, but its specific mechanism is unknown. In this study, genetic engineering technology was used to construct stable HaCaT cell lines, and the role and mechanism of ERK/CEBPB signaling pathway in arsenic-induced HaCaT cell senescence were verified by knockdown and overexpression of ERK and CEBPB in both forward and backward. It was found that knockdown of CEBPB or ERK can downregulate the ERK/CEBPB signaling pathway and reduce arsenic-induced skin cell senescence. In contrast to knockdown, overexpression of CEBPB or ERK can upregulate the ERK/CEBPB signaling pathway and aggravate the senescence of skin cells caused by arsenic. These findings suggest that sodium arsenite can further promote SASP secretion and the expression of p53, p21 and p16 INK4a by activating the ERK/CEBPB signaling pathway, induce cell cycle arrest and trigger cellular senescence.

A research landscape bibliometric analysis on climate change for last decades: Evidence from applications of machine learning

Climate change (CC) is one of the greatest threats to human health, safety, and the environment. Given its current and future impacts, numerous studies have employed computational tools (e.g., machine learning, ML) to understand, mitigate, and adapt to CC. Therefore, this paper seeks to comprehensively analyze the research/publications landscape on the MLCC research based on published documents from Scopus. The high productivity and research impact of MLCC has produced highly cited works categorized as science, technology, and engineering to the arts, humanities, and social sciences. The most prolific author is Shamsuddin Shahid (based at Universiti Teknologi Malaysia), whereas the Chinese Academy of Sciences is the most productive affiliation on MLCC research. The most influential countries are the United States and China, which is attributed to the funding activities of the National Science Foundation and the National Natural Science Foundation of China (NSFC), respectively. Collaboration through co-authorship in high-impact journals such as Remote Sensing was also identified as an important factor in the high rate of productivity among the most active stakeholders researching MLCC topics worldwide. Keyword co-occurrence analysis identified four major research hotspots/themes on MLCC research that describe the ML techniques, potential risky sectors, remote sensing, and sustainable development dynamics of CC. In conclusion, the paper finds that MLCC research has a significant socio-economic, environmental, and research impact, which points to increased discoveries, publications, and citations in the near future.

Alterations of Bax/Bcl-2 ratio contribute to NaAsO2 induced thyrotoxicity in human thyroid follicular epithelial cells and SD rats

The environmental toxicant arsenic causes various human diseases and threatens millions of people worldwide. Recently, a limited number of studies have revealed that exposure to arsenic is associated with thyroid dysfunction, indicating its toxicological impact on the thyroid gland, however, its precise forms of damage and underlying mechanisms remain largely unknown. Here, we sought to observe the thyrotoxicity of sodium arsenite (NaAsO2) on human thyroid follicular epithelial cells (Nthy-ori 3-1) and SD rats, and explore the role of Bax/Bcl-2 ratio in the above process. Our results displayed that NaAsO2 exerted a dose-dependent inhibitory effect on the viability of Nthy-ori 3-1 cells. Alongside the increase doses of NaAsO2 exposure, morphological changes and elevated LDH levels were observed. Furthermore, apoptosis rates increased in a dose- and time-dependent manner, accompanied by a decrease in Bcl-2 and an opposite change in Bax expression. SD rats were treated with 0, 2.5, 5, and 10 mg/kg NaAsO2 for 36 weeks. Our findings revealed that NaAsO2 exposure resulted in arsenic accumulation in thyroid tissue, elevated ratio of Bax/Bcl-2, and histopathological changes of thyroid in rats, which accompanied by the decreased serum T3 and T4 levels and the increased serum TSH level. Furthermore, T3 and T4 levels were negatively correlated with Bax expression, whereas positively correlated with Bcl-2 expression. Collectively, our results suggest that NaAsO2 exposure induces cytotoxicity in Nthy-ori 3-1 cells, causes structural damages and dysfunction of thyroid in SD rats, in which the imbalance of Bax/Bcl-2 ratio may play a significant role.

Anthropometric measures and arsenic methylation among pregnant women in rural northern Bangladesh

INTRODUCTION

Arsenic methylation converts inorganic arsenic (iAs) to monomethyl (MMA) and dimethyl (DMA) arsenic compounds. Body mass index (BMI) has been positively associated with arsenic methylation efficiency (higher DMA%) in adults, but evidence in pregnancy is inconsistent. We estimated associations between anthropometric measures and arsenic methylation among pregnant women in rural northern Bangladesh.

METHODS

We enrolled pregnant women (n = 784) (median [IQR] gestational week: 14 [13, 15]) in Gaibandha District, Bangladesh from 2018 to 2019. Anthropometric measures were BMI, subscapular and triceps skinfold thicknesses, and mid-upper arm circumference (MUAC), fat area (MUAFA), and muscle area (MUAMA). Arsenic methylation measures were urinary iAs, MMA, and DMA divided by their sum and multiplied by 100 (iAs%, MMA%, and DMA%), primary methylation index (MMA/iAs; PMI), and secondary methylation index (DMA/MMA; SMI). In complete cases (n = 765 [97.6%]), we fitted linear, beta, and Dirichlet regression models to estimate cross-sectional differences in iAs%, MMA%, DMA%, PMI, and SMI per IQR-unit difference in each anthropometric measure, adjusting for drinking water arsenic, age, gestational age, education, living standards index, and plasma folate, vitamin B12, and homocysteine.

RESULTS

Median (IQR) BMI, subscapular skinfold thickness, triceps skinfold thickness, MUAC, MUAFA, and MUAMA were 21.5 (19.4, 23.8) kg/m2, 17.9 (13.2, 24.2) mm, 14.2 (10.2, 18.7) mm, 25.9 (23.8, 28.0) cm, 15.3 (10.5, 20.3) cm2, and 29.9 (25.6, 34.2) cm2, respectively. Median (IQR) iAs%, MMA%, DMA%, PMI, and SMI were 12.0 (9.3, 15.2)%, 6.6 (5.3, 8.3)%, 81.0 (77.1, 84.6)%, 0.6 (0.4, 0.7), and 12.2 (9.3, 15.7), respectively. In both unadjusted and adjusted linear models, all anthropometric measures were negatively associated with iAs%, MMA%, and PMI and positively associated with DMA% and SMI. For example, fully adjusted mean differences (95% CI) in DMA% per IQR-unit difference in BMI, subscapular skinfolds thickness, triceps skinfold thickness, MUAC, MUAFA, and MUAMA were 1.72 (1.16, 2.28), 1.58 (0.95, 2.21), 1.74 (1.11, 2.37), 1.45 (0.85, 2.06), 1.70 (1.08, 2.31), and 0.70 (0.13, 1.27) pp, respectively.

CONCLUSIONS

Anthropometric measures were positively associated with arsenic methylation efficiency among pregnant women in the early second trimester.

Arsenic disrupts extracellular vesicle-mediated signaling in regenerating myofibers

Chronic exposure to environmental arsenic is a public health crisis affecting hundreds of millions of individuals worldwide. Though arsenic is known to contribute to many pathologies and diseases, including cancers, cardiovascular and pulmonary diseases, and neurological impairment, the mechanisms for arsenic-promoted disease remain unresolved. This is especially true for arsenic impacts on skeletal muscle function and metabolism, despite the crucial role that skeletal muscle health plays in maintaining cardiovascular health, systemic homeostasis, and cognition. A barrier to researching this area is the challenge of interrogating muscle cell-specific effects in biologically relevant models. Ex vivo studies investigating mechanisms for muscle-specific responses to arsenic or other environmental contaminants primarily utilize traditional 2-dimensional culture models that cannot elucidate effects on muscle physiology or function. Therefore, we developed a contractile 3-dimensional muscle construct model-composed of primary mouse muscle progenitor cells differentiated in a hydrogel matrix-to study arsenic exposure impacts on skeletal muscle regeneration. Muscle constructs exposed to low-dose (50 nM) arsenic exhibited reduced strength and myofiber diameter following recovery from muscle injury. These effects were attributable to dysfunctional paracrine signaling mediated by extracellular vesicles (EVs) released from muscle cells. Specifically, we found that EVs collected from arsenic-exposed muscle constructs recapitulated the inhibitory effects of direct arsenic exposure on myofiber regeneration. In addition, muscle constructs treated with EVs isolated from muscles of arsenic-exposed mice displayed significantly decreased strength. Our findings highlight a novel model for muscle toxicity research and uncover a mechanism of arsenic-induced muscle dysfunction by the disruption of EV-mediated intercellular communication.

A Genome-Wide Identification and Comparative Analysis of the Heavy-Metal-Associated Gene Family in Cucurbitaceae Species and Their Role in Cucurbita pepo under Arsenic Stress

The heavy-metal-associated (HMA) proteins are a class of PB1-type ATPases related to the intracellular transport and detoxification of metals. However, due to a lack of information regarding the HMA gene family in the Cucurbitaceae family, a comprehensive genome-wide analysis of the HMA family was performed in ten Cucurbitaceae species: Citrullus amarus, Citrullus colocynthis, Citrullus lanatus, Citrullus mucosospermus, Cucumis melo, Cucumis sativus, Cucurbita maxima, Cucurbita moschata, Cucurbita pepo, and Legenaria siceraria. We identified 103 Cucurbit HMA proteins with various members, ranging from 8 (Legenaria siceraria) to 14 (Cucurbita pepo) across species. The phylogenetic and structural analysis confirmed that the Cucurbitaceae HMA protein family could be further classified into two major clades: Zn/Co/Cd/Pb and Cu/Ag. The GO-annotation-based subcellular localization analysis predicted that all HMA gene family members were localized on membranes. Moreover, the analysis of conserved motifs and gene structure (intron/exon) revealed the functional divergence between clades. The interspecies microsynteny analysis demonstrated that maximum orthologous genes were found between species of the Citrullus genera. Finally, nine candidate HMA genes were selected, and their expression analysis was carried out via qRT-PCR in root, leaf, flower, and fruit tissues of C. pepo under arsenic stress. The expression pattern of the CpeHMA genes showed a distinct pattern of expression in root and shoot tissues, with a remarkable expression of CpeHMA6 and CpeHMA3 genes from the Cu/Ag clade. Overall, this study provides insights into the functional analysis of the HMA gene family in Cucurbitaceae species and lays down the basic knowledge to explore the role and mechanism of the HMA gene family to cope with arsenic stress conditions.

Membrane Functionalization Approaches toward Per- and Polyfluoroalkyl Substances and Selected Metal Ion Separations

Adsorption and ion exchange technologies are two of the most widely used approaches to separate pollutants from water; however, their intrinsic diffusion limitations continue to be a challenge. Pore functionalized membranes are a promising technology that can help overcome these challenges, but the extents of their competitive benefits and broad applicability have not been systematically evaluated. Herein, three types of adsorptive/ion exchange (IX) polymers containing strong/weak acid, strong base, and iron-chitosan complex groups were synthesized in the pores and partially on the surface of microfiltration (MF) membranes and tested for the removal of organic and inorganic cations and anions from water, including arsenic, per- and polyfluoroalkyl substances (PFAS), and calcium (hardness). When directly compared with beads (0.5-6 mm) and crushed resins (0.05 mm), adsorptive/IX pore-functionalized membranes demonstrated an increased relative sorption capacity, up to 2 orders of magnitude faster kinetics and the ability to regenerate up to 70-100% of their capacity while concentrating the initial solution concentration up to 12 times. The simple and versatile synthesis approach used to functionalize membranes, notably independent of the polymer type of the MF membrane, utilized pores throughout the entire cross section of the membrane to immobilize the polymers that contain the functional groups. Utilizing the pore volume of commercial membranes (6-112 mL/m2), the scientific weight capacity of the polymer (3.1-11.5 mequiv/g), and the synthesis conditions (e.g., monomer concentration), the theoretical adsorption/IX capacities per area of the membranes were calculated to be as high as 550 mequiv/m2, substantially higher than the 175 mequiv/m2 value needed to compete with commercially available IX resins. This work therefore shows that pore functionalized membranes are a promising path to tackle water contamination challenges, lowering separation diffusion limitations.

Draft genome sequence of Pelosinus sp. IPA-1, a bacterium isolated from arsenic-contaminated soil in Japan

Pelosinus sp. strain IPA-1 is a bacterium isolated from arsenic-contaminated soil in Japan. We here report the draft genome sequence of strain IPA-1.

Chronic Exposure to Drinking Water As, Pb, and Cd at Provisional Guideline Values Reduces Weight Gain in Male Mice via Gut Microflora Alterations and Intestinal Inflammation

Few studies have investigated the long-term effect of exposure to arsenic (As), lead (Pb), and cadmium (Cd) via drinking water at the provisional guideline values on gut microflora. In this study, male and female mice were exposed to water As, Pb, or Cd at 10, 10, or 5 μg L-1 for 6 months. At the end of the exposure, the net weight gain of male mice exposed to As and Pb (9.91 ± 1.35 and 11.2 ± 1.50 g) was significantly (p < 0.05) lower compared to unexposed control mice (14.1 ± 3.24 g), while this was not observed for female mice. Relative abundance of Akkermansia, a protective gut bacterium against intestinal inflammation, was reduced from 29.7% to 3.20%, 4.83%, and 17.0% after As, Pb, and Cd exposure in male mice, which likely caused chronic intestinal inflammation, as suggested by 2.81- to 9.60-fold higher mRNA levels of pro-inflammatory factors in ileal enterocytes of male mice. These results indicate that long-term exposure to drinking water As, Pb, and Cd at concentrations equivalent to the China provisional guideline values can cause loss of protective bacteria and lead to chronic intestinal inflammation, thereby affecting body weight gain in male mice.

Insights into the selectivity of metallic oxides for arsenic and phosphate from EXAFS and DFT calculations

Phosphate is the biggest competitor for arsenic removal. Nanoscale metal oxides (NMOs) are commonly used to treat arsenic-contaminated water, yet their selective adsorption mechanisms for arsenic and phosphate are poorly understood. We quantified the selectivity of iron oxide (Fe2O3), zinc oxide (ZnO), and titanium dioxide (TiO2) nanosheets for arsenic in systems containing arsenic and phosphate, and determined the interaction of phosphate and arsenate/arsenite on metal oxide surfaces through batch experiments, spectroscopic techniques, and DFT calculations. We found that Fe2O3, TiO2, and ZnO nanosheets exhibit selectivity for arsenate/arsenite in the presence of phosphate, with Fe2O3 the most selective, followed by TiO2 and ZnO. The bonding mechanism on these metallic oxide surfaces dominates the selectivity. The more stable inner-sphere complexes of arsenate on the surfaces of Fe2O3 (bidentate binuclear), TiO2 (bidentate binuclear), and ZnO nanosheets (tridentate trinuclear) contribute to their preference for arsenate over phosphate. This difference in arsenate selectivity can be reflected in the difference in adsorption energy, net electron transfer number, and M - O bond length of the most stable inner sphere complexes. Overall, our study elucidated the selective adsorption mechanisms of arsenate/arsenite on Fe2O3, TiO2, and ZnO surfaces and highlighted the need to consider the competition between arsenate and phosphate during their removal from contaminated water.

Solutions for an efficient arsenite oxidation and removal from groundwater containing ferrous iron

Manganese (Mn) oxides are extensively used to oxidize As(III) present in ground, drinking, and waste waters to the less toxic and more easily removable As(V). The common presence of multiple other cations in natural waters, and more especially of redox-sensitive ones such as Fe2+, may however significantly hamper As(III) oxidation and its subsequent removal. The present work investigates experimentally the influence of Mn(III) chelating agents on As(III) oxidation process in such environmentally relevant complex systems. Specifically, the influence of sodium pyrophosphate (PP), an efficient Mn(III) chelating agent, on As(III) oxidation by birnessite in the presence of Fe(II) was investigated using batch experiments at circum-neutral pH. In the absence of PP, competitive oxidation of Fe(II) and As(III) leads to Mn oxide surface passivation by Fe(III) and Mn(II/III) (oxyhydr)oxides, thus inhibiting As(III) oxidation. Addition of PP to the system highly enhances As(III) oxidation by birnessite even in the presence of Fe(II). PP presence prevents passivation of Mn oxide surfaces keeping As and Fe species in solution while lower valence Mn species are released to solution. In addition, reactive oxygen species (ROS), tentatively identified as hydroxyl radicals (•OH), are generated under aerobic conditions through oxygen activation by Fe(II)-PP complexes, enhancing As(III) oxidation further. The positive influence of Mn(III) chelating agents on As(III) oxidation most likely not only depend on their affinity for Mn(III) but also on their ability to promote formation of these active radical species. Finally, removal of As(V) through sorption to Fe (oxyhydr)oxides is efficient even in the presence of significant concentrations of PP, and addition of such Mn(III) chelating agents thus appears as an efficient way to enhance the oxidizing activity of birnessite in large-scale treatment for arsenic detoxification of groundwaters.

Enhancing arsenic adsorptions by optimizing Fe-loaded biochar and preliminary application in paddy soil under different water management strategies

Arsenic (As) is widely distributed in nature and is a highly toxic element impacting human health through drinking water and rice. In this study, an optimized approach was attempted to improve As adsorption capabilities by combining pre- and post-pyrolysis modification of Fe(oxy)hydroxides to rice husk biochar (FRB), of which the method is rarely addressed in previous studies. Maghemite and goethite were successfully loaded onto biochar, characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoemission spectroscopy (XPS) analyzer. The FRB had maximum As(III) and As(V) adsorption capabilities of 7908 and 11,268 mg/kg, respectively, which was significantly higher than that of Fe-modified biochar in the pre-pyrolysis and/or post-pyrolysis process. Adsorption mechanisms for As explored by Fourier-transform infrared spectroscopy (FTIR), XPS analysis mainly included electronic attraction and ligand exchange with hydroxyl groups on the FRB. It was noteworthy that more than half of the As(II) species loaded on FRB were converted into less toxic As(V) species, which could be mediated by the redox-active groups on the biochar. The preliminary application of FRB in soil indicated that it has an effective remediation potential for As-contaminated soil under flooded conditions, while promoted As release under dry conditions. Finding of this study highlighted that the loading of metal oxides onto biochar by combining pre- and post-pyrolysis modification could potentially increase As adsorption capabilities and further help in strategic water management.

Quantification of the redox properties of microplastics and their effect on arsenite oxidation

Microplastics have attracted global concern. The environmental-weathering processes control their fate, transport, transformation, and toxicity to wildlife and human health, but their impacts on biogeochemical redox processes remain largely unknown. Herein, multiple spectroscopic and electrochemical approaches in concert with wet-chemistry analyses were employed to characterize the redox properties of weathered microplastics. The spectroscopic results indicated that weathering of phenol-formaldehyde resins (PFs) by hydrogen peroxide (H2O2) led to a slight decrease in the content of phenol functional groups, accompanied by an increase in semiquinone radicals, quinone, and carboxylic groups. Electrochemical and wet-chemistry quantifications, coupled with microbial-chemical characterizations, demonstrated that the PFs exhibited appreciable electron-donating capacity (0.264-1.15 mmol e- g-1) and electron-accepting capacity (0.120-0.300 mmol e- g-1). Specifically, the phenol groups and semiquinone radicals were responsible for the electron-donating capacity, whereas the quinone groups dominated the electron-accepting capacity. The reversible redox peaks in the cyclic voltammograms and the enhanced electron-donating capacity after accepting electrons from microbial reduction demonstrated the reversibility of the electron-donating and -accepting reactions. More importantly, the electron-donating phenol groups and weathering-induced semiquinone radicals were found to mediate the production of H2O2 from oxygen for arsenite oxidation. In addition to the H2O2-weathered PFs, the ozone-aged PF and polystyrene were also found to have electron-donating and arsenite-oxidation capacity. This study reports important redox properties of microplastics and their effect in mediating contaminant transformation. These findings will help to better understand the fate, transformation, and biogeochemical roles of microplastics on element cycling and contaminant fate.

Non-coding RNA therapeutics: Towards a new candidate for arsenic-induced liver disease

Arsenic, a metalloid toxicant, has caused serious environmental pollution and is presently a global health issue. Long-term exposure to arsenic causes diverse organ and system dysfunctions, including liver disease. Arsenic-induced liver disease comprises a spectrum of liver pathologies, ranging from hepatocyte damage, steatosis, fibrosis, to hepatocellular carcinoma. Various mechanisms, including an imbalance in redox reactions, mitochondrial dysfunction and epigenetic changes, participate in the pathogenesis of arsenic-induced liver disease. Altered epigenetic processes involved in its initiation and progression. Dysregulated modulations of non-coding RNAs (ncRNAs), including miRNAs, lncRNAs and circRNAs, exert regulating effects on these processes. Here, we have reviewed the underlying pathogenic mechanisms that lead to progressive arsenic-induced liver disease, and we provide a discussion focusing on the effects of ncRNAs on dysfunctions in intercellular communication and on the activation of hepatic stellate cells and malignant transformation of hepatocytes. Further, we have discussed the roles of ncRNAs in intercellular communication via extracellular vesicles and cytokines, and have provided a perspective for the application of ncRNAs as biomarkers in the early diagnosis and evaluation of the pathogenesis of arsenic-induced liver disease. Further investigations of ncRNAs will help us to understand the nature of arsenic-induced liver disease and to identify biomarkers and therapeutic targets.

Arsenic exposure and lung fibrotic changes-evidence from a longitudinal cohort study and experimental models

Introduction

Arsenic (As) exposure is associated with lung toxicity and we aim to investigate the effects of arsenic exposure on lung fibrotic changes.

Methods

Participants (n= 976) enrolled via a general health survey underwent chest low-dose computed tomography (LDCT), spirometry forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and urinary arsenic examination during 2016 and 2018. Lung fibrotic changes from LDCT were defined. AsLtoL, low arsenic levels in both 2016 and 2018; AsLtoH, low arsenic in 2016 but high levels in 2018; AsHtoL, high arsenic in 2016 but low levels in 2018; AsHtoH, high arsenic levels in both 2016 and 2018. Mice exposed to 0. 0.2mg/L, 2 mg/L, 50 mg/L of sodium arsenite (NaAsO2) through drinking water for 12 weeks and 24 weeks were applied for histological analysis. Cultured lung epithelial cells were exposed to NaAsO2 and the mesenchymal changes were examined.

Results

AsHtoH increased the risk (OR= 1.65, 95% CI 1.10, 2.49) of Lung fibrotic positive to positive (reference: Lung fibrotic negative to negative) compared with AsLtoL. Moreover, the predicted mean of FVC and FEV1 in AsHtoH (-0.09 units, 95% CI: -0.27, -0.09; -0.09 units, 95% CI: -0.17, -0.01) and AsLtoH (-0.13 units, 95% CI: -0.30, -0.10; -0.13 units, 95% CI: -0.22, -0.04) was significantly lower than ASLtoL. Significant lung fibrotic changes including the increase of the alveolar septum thickness and collagen fiber deposition were observed upon 2 mg/L NaAsO2 treatment for 12 weeks, and the damage was dose- and time-dependent. In vitro, sodium arsenite treatment promotes the epithelial-mesenchymal transition (EMT)-like changes of the normal human bronchial epithelial cells, including upregulation of several fibrotic and mesenchymal markers (fibronectin, MMP-2, and Snail) and cell migration. Inhibition of reactive oxygen species (ROS) and MMP-2 impaired the arsenic-induced EMT changes. Administration of a flavonoid, apigenin, inhibited EMT in vitro and pulmonary damages in vivo with the reduction of mesenchymal markers.

Discussion

we demonstrated that continued exposure to arsenic causes lung fibrosis in humans and mice. Targeting lung epithelial cells EMT is effective on the development of therapeutic strategy. Apigenin is effective in the inhibition of arsenic-induced pulmonary fibrosis and EMT.

Anoxygenic phototrophic purple non-sulfur bacteria: tool for bioremediation of hazardous environmental pollutants

The extraordinary metabolic flexibility of anoxygenic phototrophic purple non-sulfur bacteria (PNSB) has been exploited in the development of various biotechnological applications, such as wastewater treatment, biohydrogen production, improvement of soil fertility and plant growth, and recovery of high-value compounds. These versatile microorganisms can also be employed for the efficient bioremediation of hazardous inorganic and organic pollutants from contaminated environments. Certain members of PNSB, especially strains of Rhodobacter sphaeroides and Rhodopseudomonas palustris, exhibit efficient remediation of several toxic and carcinogenic heavy metals and metalloids, such as arsenic, cadmium, chromium, and lead. PNSB are also known to utilize diverse biomass-derived lignocellulosic organic compounds and xenobiotics. Although biodegradation of some substituted aromatic compounds by PNSB has been established, available information on the involvement of PNSB in the biodegradation of toxic organic pollutants is limited. In this review, we present advancements in the field of PNSB-based bioremediation of heavy metals and organic pollutants. Furthermore, we highlight that the potential role of PNSB as a promising bioremediation tool remains largely unexplored. Thus, this review emphasizes the necessity of investing extensive research efforts in the development of PNSB-based bioremediation technology.

C/EBPβ-TFAM-Mediated NLRP3 Inflammasome Activation Contributes to Arsenic-Induced Rat Kidney Injury

Compelling evidence has demonstrated that arsenic (As) exposure is associated with kidney injuries. Given that inflammatory responses and immune imbalances are the root causes of several kidney diseases, this study investigated the potential mechanisms underlying NLRP3 inflammasome activation in As-induced kidney injury. A rat model of sub-chronic As exposure was established via oral administration of NaAsO2. The results revealed that urinary β-2-microglobulin (β2-MG), N-acetyl-β-D-glucosidase (NAG) and albumin (ALB) were increased in the As-exposed group, reflecting kidney impairment. Moreover, significant glomerular vacuole-like changes, tubular dilatation and inflammatory cell infiltration were observed. Meanwhile, the expression levels of neutrophil gelatinase-associated lipocalin (NGAL), IL-1β and IL-18 were enhanced in the kidney tissues of As-treated rats. Further, increased expression of NLRP3, ASC and caspase-1, which are NLRP3 inflammasome-associated proteins, were observed in the kidney tissues of rats in the As-treated groups. The expression levels of the NLRP3 upstream regulators C/EBPβ and TFAM were also elevated. These findings suggest that sub-chronic As exposure triggers inflammatory responses in rat kidney tissue and impairs kidney function. The underlying mechanisms may be related to the C/EBPβ-TFAM pathway and activation of the NLRP3 inflammasome pathway.

Integrated data-driven cross-disciplinary framework to prevent chemical water pollution

Access to a clean and healthy environment is a human right and a prerequisite for maintaining a sustainable ecosystem. Experts across domains along the chemical life cycle have traditionally operated in isolation, leading to limited connectivity between upstream chemical innovation to downstream development of water-treatment technologies. This fragmented and historically reactive approach to managing emerging contaminants has resulted in significant externalized societal costs. Herein, we propose an integrated data-driven framework to foster proactive action across domains to effectively address chemical water pollution. By implementing this integrated framework, it will not only enhance the capabilities of experts in their respective fields but also create opportunities for novel approaches that yield co-benefits across multiple domains. To successfully operationalize the integrated framework, several concerted efforts are warranted, including adopting open and FAIR (findable, accessible, interoperable, and reusable) data practices, developing common knowledge bases/platforms, and staying vigilant against new substance "properties" of concern.

The machine learning and geostatistical approach for assessment of arsenic contamination levels using physicochemical properties of water

Arsenic contamination in groundwater due to natural or anthropogenic sources is responsible for carcinogenic and non-carcinogenic risks to humans and the ecosystem. The physicochemical properties of groundwater in the study area were determined in the laboratory using the samples collected across the Varanasi region of Uttar Pradesh, India. This paper analyses the physicochemical properties of water using machine learning, descriptive statistics, geostatistical and spatial analysis. Pearson correlation was used for feature selection and highly correlated features were selected for model creation. Hydrochemical facies of the study area were analyzed and the hyperparameters of machine learning models, i.e., multilayer perceptron, random forest (RF), naïve Bayes, and decision tree were optimized before training and testing the groundwater samples as high (1) or low (0) arsenic contamination levels based on the WHO 10 μg/L guideline value. The overall performance of the models was compared based on accuracy, sensitivity, and specificity value. Among all models, the RF algorithm outclasses other classifiers, as it has a high accuracy of 92.30%, a sensitivity of 100%, and a specificity of 75%. The accuracy result was compared to prior research, and the machine learning model may be used to continually monitor the amount of arsenic pollution in groundwater.

Use of agricultural bio-wastes to remove arsenic from contaminated water

Arsenic (As) is a highly toxic metalloid. High As levels have been recorded in groundwater aquifers at a global scale. This study investigated As level in groundwater of District Vehari and assessed the potential of different agricultural by-products (sugarcane bagasse, cottonseed hulls, soybean hulls, corncobs and rice husk) to remove As from water. The study was carried out in two steps. In the first step, a total of 38 groundwater samples were obtained from Vehari. Groundwater samples were analyzed for total As contents and physicochemical parameters. Results indicated that As content ranged from below detection limit to 49 µg/L in the groundwater samples. The values of hazard quotient and cancer risk were up to 1.5 and 0.0004, respectively, which delineated severe risk of As poisoning. During the second step, six As-contaminated groundwater samples (total As contents: 49, 40, 29, 24, 18, 16 µg/L) were selected to remove As using agricultural by-products. Furthermore, four As solutions (200, 100, 50 and 25 µg/L) were prepared in the laboratory. Results revealed that corncobs and soybean hulls removed, respectively, 98% and 71% As from aqueous mediums after 120 min. Moreover, agricultural by-products were less effective in removing As from groundwater samples than synthetic solutions. The adsorption/removal capacity of by-products was lower at low initial As concentration compared to high initial levels, which needs further studies to explore the underlying mechanisms. Overall, the As removal efficiency of agriculture by-products differed significantly with respect to initial As level, contamination category, type of agricultural by-products and interaction duration. Therefore, these aspects need to be optimized before the possible use of an agricultural by-product as a potential biosorbent.

Differential effects of arsenite and arsenate on rice (Oryza sativa) plants differing in glutathione S-transferase gene expression

Contamination of paddy soils with arsenic (As) can cause phytotoxicity in rice and increase the accumulation of arsenic in grains. The uptake and accumulation of As in rice depends on the different As species present in the soil. Plants detoxify As by conjugating and sequestering xenobiotic compounds into vacuoles using various enzymes. However, the severity of damage induced by arsenite (As(III)) and arsenate (As(V)), as well as the roles of glutathione S-transferase in detoxifying these As species in rice, are not fully understood. In this study, we developed plant materials overexpressing a glutathione S-transferase gene OsGSTU40 under the control of the maize UBIL promoter. Through systematic investigations of both wild-type Nipponbare (Oryza sativa L., ssp. japonica) and OsGSTU40 overexpression lines under chronic or acute stress of As, we aimed to understand the toxic effects of both As(III) and As(V) on rice plants at the vegetative growth stage. We hypothesized that (i) As(III) and As(V) have different toxic effects on rice plants and (ii) OsGSTU40 played positive roles in As toxicity tolerance. Our results showed that As(III) was more detrimental to plant growth than As(V) in terms of plant growth, biomass, and lipid peroxidation in both chronic and acute exposure. Furthermore, overexpression of OsGSTU40 led to better plant growth even though uptake of As(V), but not As(III), into shoots was enhanced in transgenic plants. In acute As(III) stress, transgenic plants exhibited a lower level of lipid peroxidation than wild-type plants. The element composition of plants was dominated by the different As stress treatments rather than by the genotype, while the As concentration was negatively correlated with phosphorus and silicon. Overall, our findings suggest that As(III) is more toxic to plants than As(V) and that glutathione S-transferase OsGSTU40 differentially affects plant reactions and tolerance to different species of arsenic.

Arsenic exposure induced anxiety-like behaviors in male mice via influencing the GABAergic Signaling in the prefrontal cortex

Arsenic contamination in drinking water causes a global public health problem. Emerging evidence suggests that arsenic may act as an environmental risk factor for anxiety disorders. However, the exact mechanism underlying the adverse effects has not been fully elucidated. This study aimed to evaluate the anxiety-like behaviors of mice exposed to arsenic trioxide (As2O3), to observe the neuropathological changes, and to explore the link between the GABAergic system and behavioral manifestations. For this purpose, male C57BL/6 mice were exposed to various doses of As2O3 (0, 0.15, 1.5, and 15 mg/L) through drinking water for 12 weeks. Anxiety-like behaviors were assessed using the open field test (OFT), light/dark choice test, and elevated zero maze (EZM). Neuronal injuries in the cerebral cortex and hippocampus were assessed by light microscopy with H&E and Nissl staining. Ultrastructural alteration in the cerebral cortex was assessed by transmission electron microscope (TEM). The expression levels of GABAergic system-related molecules (i.e., glutamate decarboxylase, GABA transporter, and GABAB receptor subunits) in the prefrontal cortex (PFC) were determined by qRT-PCR and western blotting. Arsenic exposure showed a striking anxiogenic effect on mice, especially in the group exposed to 15 mg/L As2O3. Light microscopy showed neuron necrosis and reduced cell counts. TEM revealed marked ultrastructural changes, including the vacuolated mitochondria, disrupted Nissl bodies, an indentation in the nucleus membrane, and delamination of myelin sheath in the cortex. In addition, As2O3 influenced the GABAergic system in the PFC by decreasing the expression of the glutamate decarboxylase 1 (GAD1) and the GABAB2 receptor subunit, but not the GABAB1 receptor subunit. To sum up, sub-chronic exposure to As2O3 is associated with increased anxiety-like behaviors, which may be mediated by altered GABAergic signaling in the PFC. These findings shed light on the mechanisms responsible for the neurotoxic effects of arsenic and therefore more cautions should be taken.

GIS based hotspot analysis and health risk assessment of groundwater arsenic from an unconfined deep aquifer of Lahore, Pakistan

Use of groundwater for drinking purpose poses serious hazards of arsenic contamination particularly in plains of western Himalayan region. Therefore, current study was designed to investigate the level of Arsenic (As) in the water obtained from tubewells in a metropolitan city of Lahore, Pakistan and assess the human health risk. So, a total of 73 tubewells were sampled randomly in the manner that the whole study region was covered without any clustering. The water samples were analyzed for As using atomic absorption spectrophotometer. These samples were also tested for total dissolved solids, chlorides, pH, alkalinity, turbidity, hardness and calcium. GIS based hotspots analysis technique was used to investigate the spatial distribution patterns. Our results revealed that only one sample out of total 73 had arsenic level below the WHO guideline of 10 μg/L. The spatial distribution map of arsenic revealed that the higher concentrations of arsenic are present in the north-western region of Lahore. The cluster and outlier analysis map using Anselin Local Moran's I statistic indicated the presence of an arsenic cluster in the west of River Ravi. Furthermore, the optimized hotspot analysis based on Getis-Ord Gi* statistics confirmed the statistical significance (P < 0.05) and (P < 0.01) of these samples from the vicinity of River Ravi. Regression analysis showed that variables such as turbidity, alkalinity, hardness, chlorides, calcium and total dissolved solids were significantly (all P < 0.05) associated with level of Arsenic in tubewells. Whereas, PH and electrical conductivity and other variables like town, year of installation, depth and diameter of the wells were not significantly associated with Arsenic concentrations in tubewells. Principal component analysis (PCA) exhibited that the random distribution of tubewell samples showed no distinct clustering with towns studied. Health risk assessment based on hazard and Cancer risk index revealed serious risk of developing carcinogenic and non-carcinogenic diseases particularly in children. The health risk due to prevalence of high As concentration in tubewells' water need to be mitigated immediately to avoid worst consequences in future.

Environmental fate and ecological impact of the potentially toxic elements from the geothermal springs

Potentially toxic elements from geothermal springs can cause significant pollution of the surrounding environment and pose potential risk to the ecosystem. The fate of potentially toxic elements in the water-soil-plant system in the Yangbajain geothermal field on the Tibetan Plateau, China was investigated to assess their impact on the eco-environment. The concentrations of Be, F, As, and Tl were highly elevated in the headwaters of the Yangbajain geothermal springs, and their concentrations in the local surface water impacted by the geothermal springs reached 8.1 μg/L (Be), 23.9 mg/L (F), 3.83 mg/L (As), and 8.4 μg/L (Tl), respectively, far exceeding the corresponding thresholds for surface and drinking water. The absence of As-Fe co-precipitation, undersaturated F-, and weak adsorption on minerals at high geothermal spring pH may be responsible for the As- and F-rich drainage, which caused pollution of local river. As concentrations in the leaves of Orinus thoroldii (Stapf ex Hemsl.) Bor were up to 42.7 μg/g (dry weight basis), which is an order of magnitude higher than the allowable limit in animal feeds. The locally farmed yaks are exposed to the excessive amount of F and As with high exposure risk through water-drinking and grass-feeding.

Arsenite oxidase in complex with antimonite and arsenite oxyanions: Insights into the catalytic mechanism

Arsenic contamination of groundwater is among one of the biggest health threats affecting millions of people in the world. There is an urgent need for efficient arsenic biosensors where the use of arsenic metabolizing enzymes can be explored. In this work, we have solved four crystal structures of arsenite oxidase (Aio) in complex with arsenic and antimony oxyanions and the structures determined correspond to intermediate states of the enzymatic mechanism. These structural data were complemented with density-functional theory calculations providing a unique view of the molybdenum active site at different time points that, together with mutagenesis data, enabled to clarify the enzymatic mechanism and the molecular determinants for the oxidation of As(III) to the less toxic As(V) species.

Transcriptomic Effects of Low-Dose Inorganic Arsenic Exposure on Murine Bone Marrow-Derived Macrophages

Both tissue-resident macrophages and monocytes recruited from the bone marrow that transform into tissue-resident cells play critical roles in mediating homeostasis as well as in the pathology of inflammatory diseases. Inorganic arsenic (iAs) is the most common drinking water contaminant worldwide and represents a major public health concern. Several diseases that macrophages have implicated involvement in are caused by iAs exposure, including cardiovascular disease, cancer, and increased risk of infectious disease. Therefore, understanding the effects of iAs exposure on macrophages can help us better grasp the full range of arsenic immunotoxicity and better design therapeutic targets for iAs-induced diseases particularly in exposed populations. In this study, we analyzed the transcriptome of low dose iAs-exposed male and female murine bone marrow-derived macrophages (BMDMs) with either M0, M1, or M2 stimulation. We identified differentially expressed genes by iAs in a sex- and stimulation-dependent manner and used bioinformatics tools to predict protein-protein interactions, transcriptional regulatory networks, and associated biological processes. Overall, our data suggest that M1-stimulated, especially female-derived, BMDMs are most susceptible to iAs exposure. Most notably, we observed significant downregulation of major proinflammatory transcription factors, like IRF8, and its downstream targets, as well as genes encoding proteins involved in pattern recognition and antigen presentation, such as TLR7, TLR8, and H2-D1, potentially providing causal insight regarding arsenic's role in perturbing immune responses to infectious diseases. We also observed significant downregulation of genes involved in processes crucial to coordinating a proinflammatory response including leukocyte migration, differentiation, and cytokine and chemokine production and response. Finally, we discovered that 24 X-linked genes were dysregulated in iAs-exposed female stimulation groups compared to only 3 across the iAs-exposed male stimulation groups. These findings elucidate the potential mechanisms underlying the sex-differential iAs-associated immune-related disease risk.

Arsenic speciation in freshwater fish: challenges and research needs

Food and water are the main sources of human exposure to arsenic. It is important to determine arsenic species in food because the toxicities of arsenic vary greatly with its chemical speciation. Extensive research has focused on high concentrations of arsenic species in marine organisms. The concentrations of arsenic species in freshwater fish are much lower, and their determination presents analytical challenges. In this review, we summarize the current state of knowledge on arsenic speciation in freshwater fish and discuss challenges and research needs. Fish samples are typically homogenized, and arsenic species are extracted using water/methanol with the assistance of sonication and enzyme treatment. Arsenic species in the extracts are commonly separated using high-performance liquid chromatography (HPLC) and detected using inductively coupled plasma mass spectrometry (ICPMS). Electrospray ionization tandem mass spectrometry, used in combination with HPLC and ICPMS, provides complementary information for the identification and characterization of arsenic species. The methods and perspectives discussed in this review, covering sample preparation, chromatography separation, and mass spectrometry detection, are directed to arsenic speciation in freshwater fish and applicable to studies of other food items. Despite progress made in arsenic speciation analysis, a large fraction of the total arsenic in freshwater fish remains unidentified. It is challenging to identify and quantify arsenic species present in complex sample matrices at very low concentrations. Further research is needed to improve the extraction efficiency, chromatographic resolution, detection sensitivity, and characterization capability.

Evaluating the Hydrological Components Contributions to Terrestrial Water Storage Changes in Inner Mongolia with Multiple Datasets

In this study, multiple remote sensing data were used to quantitatively evaluate the contributions of surface water, soil moisture and groundwater to terrestrial water storage (TWS) changes in five groundwater resources zones of Inner Mongolia (GW_I, GW_II, GW_III, GW_IV and GW_V), China. The results showed that TWS increased at the rate of 2.14 mm/a for GW_I, while it decreased at the rate of 4.62 mm/a, 5.89 mm/a, 2.79 mm/a and 2.62 mm/a for GW_II, GW_III, GW_IV and GW_V during 2003-2021. Inner Mongolia experienced a widespread soil moisture increase with the rate of 4.17 mm/a, 2.13 mm/a, 1.20 mm/a, 0.25 mm/a and 1.36 mm/a for the five regions, respectively. Significant decreases were detected for regional groundwater storage (GWS) with the rate of 2.21 mm/a, 6.76 mm/a, 6.87 mm/a, 3.01 mm/a, and 4.14 mm/a, respectively. Soil moisture was the major contributor to TWS changes in GW_I, which accounted 58% of the total TWS changes. Groundwater was the greatest contributor to TWS changes in other four regions, especially GWS changes, which accounted for 76% TWS changes in GW_IV. In addition, this study found that the role of surface water was notable for calculating regional GWS changes.

Mechanistic Study of Arsenate Adsorption onto Different Amorphous Grades of Titanium (Hydr)Oxides Impregnated into a Point-of-Use Activated Carbon Block

Millions of households still rely on drinking water from private wells or municipal systems with arsenic levels approaching or exceeding regulatory limits. Arsenic is a potent carcinogen, and there is no safe level of it in drinking water. Point-of-use (POU) treatment systems are a promising option to mitigate arsenic exposure. However, the most commonly used POU technology, an activated carbon block filter, is ineffective at removing arsenic. Our study aimed to explore the potential of impregnating carbon blocks with amorphous titanium (hydr)oxide (THO) to improve arsenic removal without introducing titanium (Ti) into the treated water. Four synthesis methods achieved 8-16 wt.% Ti loading within the carbon block with 58-97% amorphous THO content. The THO-modified carbon block could adsorb both oxidation states of arsenic (arsenate and arsenite) in batch or column tests. Modified carbon block with higher Ti and amorphous content always led to better arsenate removal, achieving arsenic loadings up to 31 mg As/mg Ti after 70,000 bed volumes in continuous flow tests. Impregnating carbon block with amorphous THO consistently outperformed impregnation using crystalline TiO2. The best-performing system (TTIP-EtOH carbon block) was an amorphous THO derived using titanium isopropoxide, ethanol, and acetic acid via sol-gel technique, aged at 80° for 18 hours and dried overnight at 60°. Comparable pore size distribution and surface area of the impregnated carbon blocks suggested that chemical properties play a more crucial role than physical and textural properties in removing arsenate via amorphous Ti-impregnated carbon block. Freundlich isotherms indicated energetically favorable adsorption for amorphous chemically synthesized adsorbents. The mass transport coefficients for the amorphous TTIP-EtOH carbon block were fitted using a pore surface diffusion model, resulting in Dsurface = 3.1×10-12 cm2/s and Dpore = 3.2×10-6 cm2/s. Impregnating the carbon block with THO enabled effective arsenic removal from water without adversely affecting the pressure drop across the unit or the carbon block's ability to remove polar organic chemical pollutants efficiently.

Anthropogenic processes drive heterogeneous distributions of toxic elements in shallow groundwater around a smelting site

Smelting activities have a far-reaching influence on the quality of soil and groundwater, while most studies have neglected the information on the pollution characteristics of groundwater. The hydrochemical parameters of shallow groundwater and the spatial distributions of toxic elements were investigated in this study. Correlations analysis and groundwater evolution revealed that the major ions were primarily determined by silicate weathering and calcite dissolution process, and anthropogenic processes had a significant effect on groundwater hydrochemistry. Almost 79%, 71%, 57%, 89%, 100%, and 78.6% of samples exceeded the standards of Cd, Zn, Pb, As, SO₄^2-, and NO₃^-, and their distribution is closely related to the production process. Analysis of soil geochemistry indicated that the relatively mobile forms of toxic elements strongly influence the origin and concentration in shallow groundwater. Besides, rainfall with high magnitude would lead to a decrease of toxic elements in shallow groundwater, whereas the area once stacked waste residue was the opposite. It is recommended to strengthen risk management of the limited mobility fraction while devising a plan for waste residue treatment in accordance with the local pollution conditions. The research on controlling the mechanism of toxic elements in shallow groundwater, along with sustainable development in the study area and other smelting zones may benefit from this study.

The Protective Effects of Trametes Versicolor on Arsenic-Induced Male Reproductive Toxicity through Regulation of Oxidative Stress: A Biochemical and Histopathological Survey

Exposure to arsenic is linked to a wide range of diseases, in particular male reproductive toxicities. Trametes versicolor is a traditional medicinal fungus with a remarkable potential for antioxidant activity. The purpose of this study was to examine the ameliorating effects of water and methanol extracts of T. versicolor on arsenic-induced male reproductive toxicities via the abrogation of oxidative stress. The mice were divided as follows: control: normal saline, As: arsenic (15 mg/kg), WE: water extract (400 mg/kg), ME: methanol extract (400 mg/kg), As + WE: arsenic (15 mg/kg) + water extract (100, 200, 400 mg/kg), As + ME: arsenic (15 mg/kg) + methanol extract (100, 200, 400 mg/kg), and positive control: arsenic (15 mg/kg) + vitamin C (500 mg/kg). Animals were treated via the intraperitoneal route. About 24 hr later, the mice were euthanized, and oxidative stress parameters (reactive oxygen species [ROS], lipid peroxidation, glutathione concentration, protein carbonylation, glutathione peroxidase, and superoxide dismutase activity), histopathological changes and sperm parameters (count, motility, and morphology) were examined in the testicular tissue. Arsenic caused significant pathological changes in the testicular tissue and sperm morphology and significantly reduced sperm count and motility. Moreover, arsenic mediated oxidative stress via significant increases in ROS generation, lipid peroxidation, and protein carbonyl content, as well as significant depletion in glutathione concentration and superoxide dismutase and glutathione peroxidase activities. Although, coadministration of water and methanol extracts of T. versicolor at 200 and 400 mg/kg counteracted arsenic-induced oxidative and histopathological damages and improved sperm parameters. Our study indicated that T. versicolor ameliorated arsenic-induced testis toxicity and sperm dysfunction via attenuation of oxidative damage.

Speciation of inorganic arsenic with mixed mode HPLC-ESI-MS and Arsenite Oxidation

It has been challenging to analyze inorganic arsenic (iAs) with anion exchange HPLC-Electrospray Ionization-Mass spectrometry (HPLC-ESI-MS), because arsenite (As(III)) is difficult to retain on column and the salts in mobile phase causes ionization suppression of iAs. To address these issues, a method has been developed involving the determination of arsenate (As(V)) with mixed mode HPLC-ESI-MS and the conversion of As(III) to As(V) for total iAs. As(V) was separated from other chemicals on Newcrom B, a bi-modal HPLC column involving anion exchange and reverse phase interaction. The elution employed a two-dimensional gradient, including a formic acid gradient to elute As(V) and a concurrent alcohol gradient to elute organic anions used in sample preparations. As(V) was detected by Selected Ion Recording (SIR) in negative mode at m/z = 141 with a QDa (single quad) detector. As(III) was quantitatively converted to As(V) by mCPBA oxidation and measured for total iAs. By replacing salt with formic acid in elution, the ionization efficiency for As(V) was greatly enhanced in ESI interface. The limit of detection (LOD) for As(V) and As(III) were 0.0263 μM (1.97 ppb) and 0.0398 μM (2.99 ppb), respectively. The linear range was 0.05-1 μM. The method has been used to characterize iAs speciation change in the solution and precipitation in a simulated iron-rich groundwater caused by air exposure.

Highly active complexes of pyrite and organic matter regulate arsenic fate

Arsenic (As) presents high toxicity and strong carcinogenicity, and its health risks are regulated by its oxidation state and speciation. As can form complexes with the surface of minerals or organic matter through adsorption, affecting its toxicity and bioavailability. However, the regulation effect of the interaction of coexisting minerals and organic matter on As fate remains largely unknown. Here, we discovered that minerals (e.g., pyrite) and organic matter (e.g., alanyl glutamine, AG) can form pyrite-AG complexes, promoting As(III) oxidation under simulated solar irradiation. The formation of pyrite-AG was explored in terms of the interaction of surface oxygen atoms, electron transfer and crystal surface changes. From the perspective of atoms and molecules, pyrite-AG showed more oxygen vacancies, stronger reactive oxygen species (ROS) and a higher electron transport capacity than pyrite alone. Compared with pyrite, pyrite-AG effectively promoted the conversion of highly toxic As(III) to less toxic As(V) due to the enhanced photochemical properties. Moreover, quantification and capture of ROS confirmed that hydroxyl radicals (•OH) played an important role in As(III) oxidation in the pyrite-AG and As(III) system. Our results provide previously unidentified perspectives on the effects and chemical mechanisms of highly active complexes of mineral and organic matter on As fate and provide new insights into the risk assessment and control of As pollution.

Association of obesity, diabetes, and hypertension with arsenic in drinking water in the Comarca Lagunera province (north-central Mexico)

Chronic endemic regional hydroarsenicism (CERHA) is a global issue that affects over 200 million people exposed to arsenic (As) in drinking water. This includes 1.75 million individuals residing in La Comarca Lagunera, a region in north-central Mexico. Arsenic levels in this region typically exceeds the WHO guideline of 10 µg L^-1. Biochemical alterations related to the human As metabolism may increase the risk of overweight and obesity (O&O), type 2 diabetes (T2D), and hypertension (AHT). In our study, we investigated the role of As in drinking water as a risk factor for these metabolic diseases. We focused on populations with historically moderate (San Pedro) and low (Lerdo) drinking water As levels and people with no historical evidence of As water contamination. The exposure assessment to As was based on measurements of the drinking water (medians 67.2, 21.0, 4.3 µg L^-1) and urinary As concentrations in women (9.4, 5.3, 0.8 µg L^-1) and men (18.1, 4.8, 1.0 µg L^-1). A significant correlation between As in drinking water and urine evidenced the As exposure in the population (R² = 0.72). Adjusted odds ratios with 95% confidence intervals evidenced higher chances of being diagnosed with T2D (1.7, 1.2-2.0) and AHT (1.8, 1.7-1.9) in individuals living in San Pedro than those in Lerdo. Still, there was no significant association with obesity. Individuals living in CERHA towns were found to have a higher risk of obesity (1.3-1.9), T2D (1.5 to 3.3), and AHT (1.4 to 2.4) compared to those residing in non-CERHA towns. Finally, obesity is more probable in women [inverse of OR and 95%CI 0.4 (0.2-0.7)] compared to men, while men is more likely to be diagnosed with T2D [OR = 2.0 (1.4-2.3)] and AHT [OR = 2.0 (1.5-2.3)] than women, independently of the municipality.

Insights into the statistical physics modeling and fractal like kinetic approach for the adsorption of As(III) on coordination polymer gel based on zirconium(IV) and 2-thiobarbituric acid

A novel coordination polymer gel based on zirconium(IV) and 2-thiobarbituric (ZrTBA) was synthesized and explored its potential to remediate As(III) from water. Box-Behnken design with desirability function and genetic algorithm yielded the optimized conditions (initial concentration=194 mg L^-1, dosage = 42.2 mg, time= 95 min and pH = 4.9) for maximum removal efficiency (99.19 %). The experimental saturation capacity for As(III) was 178.30 mg g^-1. The steric parameter n > 1 of the best fitted statistical physics model: monolayer with two energies (R² = 0.987-0.992) suggested multimolecular mechanism with vertical orientation of As(III) molecules onto the two active sites. XPS and FTIR confirmed the two active sites being zirconium and oxygen. The adsorption energies (E₁ = 35.81-37.63 kJ/mol; E₂ = 29.50-36.49 kJ/mol) and isosteric heat of adsorption indicated that physical forces governed the As(III) uptake. DFT calculations implied that the weak electrostatic interaction and hydrogen bonding were involved. The best fitted (R²>0.99) fractal like pseudo first order model established energetic heterogeneity. ZrTBA showed excellent removal efficiency in the presence of potential interfering ions and could be used up to 5 cycles of adsorption-desorption with < 8 % loss in the efficiency. ZrTBA removed ≥96.06 % As(III) from real water samples spiked at different levels of As(III).