Roles of serum uric acid on the association between arsenic exposure and incident metabolic syndrome in an older Chinese population.

Growing evidences showed that heavy metals exposure may be associated with metabolic diseases. Nevertheless, the mechanism underlying arsenic (As) exposure and metabolic syndrome (MetS) risk has not been fully elucidated. So we aimed to prospectively investigate the role of serum uric acid (SUA) on the association between blood As exposure and incident MetS. A sample of 1045 older participants in a community in China was analyzed. We determined As at baseline and SUA concentration at follow-up in the Yiwu Elderly Cohort. MetS events were defined according to the criteria of the International Diabetes Federation (IDF). Generalized linear model with log-binominal regression model was applied to estimate the association of As with incident MetS. To investigate the role of SUA in the association between As and MetS, a mediation analysis was conducted. In the fully adjusted log-binominal model, per interquartile range increment of As, the risk of MetS increased 1.25-fold. Compared with the lowest quartile of As, the adjusted relative risk (RR) of MetS in the highest quartile was 1.42 (95% confidence interval, CI: 1.03, 2.00). Additionally, blood As was positively associated with SUA, while SUA had significant association with MetS risk. Further mediation analysis demonstrated that the association of As and MetS risk was mediated by SUA, with the proportion of 15.7%. Our study found higher As was remarkably associated with the elevated risk of MetS in the Chinese older adults population. Mediation analysis indicated that SUA might be a mediator in the association between As exposure and MetS.

Arsenic exposure and oxidative damage to lipid, DNA, and protein among general Chinese adults: A repeated-measures cross-sectional and longitudinal study.

Arsenic-related oxidative stress and resultant diseases have attracted global concern, while longitudinal studies are scarce. To assess the relationship between arsenic exposure and systemic oxidative damage, we performed two repeated measures among 5236 observations (4067 participants) in the Wuhan-Zhuhai cohort at the baseline and follow-up after 3 years. Urinary total arsenic, biomarkers of DNA oxidative damage (8-hydroxy-2'-deoxyguanosine (8-OHdG)), lipid peroxidation (8-isoprostaglandin F2alpha (8-isoPGF2α)), and protein oxidative damage (protein carbonyls (PCO)) were detected for all observations. Here we used linear mixed models to estimate the cross-sectional and longitudinal associations between arsenic exposure and oxidative damage. Exposure-response curves were constructed by utilizing the generalized additive mixed models with thin plate regressions. After adjusting for potential confounders, arsenic level was significantly and positively related to the levels of global oxidative damage and their annual increased rates in dose-response manners. In cross-sectional analyses, each 1% increase in arsenic level was associated with a 0.406% (95% confidence interval (CI): 0.379% to 0.433%), 0.360% (0.301% to 0.420%), and 0.079% (0.055% to 0.103%) increase in 8-isoPGF2α, 8-OHdG, and PCO, respectively. More importantly, arsenic was further found to be associated with increased annual change rates of 8-isoPGF2α (ß: 0.147; 95% CI: 0.130 to 0.164), 8-OHdG (0.155; 0.118 to 0.192), and PCO (0.050; 0.035 to 0.064) in the longitudinal analyses. Our study suggested that arsenic exposure was not only positively related with global oxidative damage to lipid, DNA, and protein in cross-sectional analyses, but also associated with annual increased rates of these biomarkers in dose-dependent manners.

Predicting the efficiency of arsenic immobilization in soils by biochar using machine learning.

Arsenic (As) pollution in soils is a pervasive environmental issue. Biochar immobilization offers a promising solution for addressing soil As contamination. The efficiency of biochar in immobilizing As in soils primarily hinges on the characteristics of both the soil and the biochar. However, the influence of a specific property on As immobilization varies among different studies, and the development and application of arsenic passivation materials based on biochar often rely on empirical knowledge. To enhance immobilization efficiency and reduce labor and time costs, a machine learning (ML) model was employed to predict As immobilization efficiency before biochar application. In this study, we collected a dataset comprising 182 data points on As immobilization efficiency from 17 publications to construct three ML models. The results demonstrated that the random forest (RF) model outperformed gradient boost regression tree and support vector regression models in predictive performance. Relative importance analysis and partial dependence plots based on the RF model were conducted to identify the most crucial factors influencing As immobilization. These findings highlighted the significant roles of biochar application time and biochar pH in As immobilization efficiency in soils. Furthermore, the study revealed that Fe-modified biochar exhibited a substantial improvement in As immobilization. These insights can facilitate targeted biochar property design and optimization of biochar application conditions to enhance As immobilization efficiency.

Development of a coupled model to simulate and assess arsenic contamination and impact factors in the Jinsha River Basin, China.

With the increasing severity of arsenic (As) pollution, quantifying the environmental behavior of pollutant based on numerical model has become an important approach to determine the potential impacts and finalize the precise control strategies. Taking the industrial-intensive Jinsha River Basin as typical area, a two-dimensional hydrodynamic water quality model coupled with Soil and Water Assessment Tool (SWAT) model was developed to accurately simulate the watershed-scale distribution and transport of As in the terrestrial and aquatic environment at high spatial and temporal resolution. The effects of hydro-climate change, hydropower station construction and non-point source emissions on As were quantified based on the coupled model. The result indicated that higher As concentration areas mainly centralized in urban districts and concentration slowly decreased from upstream to downstream. Due to the enhanced rainfall, the As concentration was significantly higher during the rainy season than the dry season. Hydro-climate change and the construction of hydropower station not only affected the dissolved As concentration, but also affected the adsorption and desorption of As in sediment. Furthermore, As concentration increased with the input of non-point source pollution, with the maximum increase about 30%, resulting that non-point sources contributed important pollutant impacts to waterways. The coupled model used in pollutant behavior analysis is general with high potential application to predict and mitigate water pollution.

Assessment of internal exposure risk from metals pollution of occupational and non-occupational populations around a non-ferrous metal smelting plant.

Non-ferrous metal smelting poses significant risks to public health. Specifically, the copper smelting process releases arsenic, a semi-volatile metalloid, which poses an emerging exposure risk to both workers and nearby residents. To comprehensively understand the internal exposure risks of metal(loid)s from copper smelting, we explored eighteen metal(loid)s and arsenic metabolites in the urine of both occupational and non-occupational populations using inductively coupled plasma mass spectrometry with high-performance liquid chromatography and compared their health risks. Results showed that zinc and copper (485.38 and 14.00 µg/L), and arsenic, lead, cadmium, vanadium, tin and antimony (46.80, 6.82, 2.17, 0.40, 0.44 and 0.23 µg/L, respectively) in workers (n=179) were significantly higher compared to controls (n=168), while Zinc, tin and antimony (412.10, 0.51 and 0.15 µg/L, respectively) of residents were significantly higher than controls. Additionally, workers had a higher monomethyl arsenic percentage (MMA%), showing lower arsenic methylation capacity. Source appointment analysis identified arsenic, lead, cadmium, antimony, tin and thallium as co-exposure metal(loid)s from copper smelting, positively relating to the age of workers. The hazard index (HI) of workers exceeded 1.0, while residents and control were approximately at 1.0. Besides, all three populations had accumulated cancer risks exceeding 1.0 × 10-4, and arsenite (AsIII) was the main contributor to the variation of workers and residents. Furthermore, residents living closer to the smelting plant had higher health risks. This study reveals arsenic exposure metabolites and multiple metals as emerging contaminants for copper smelting exposure populations, providing valuable insights for pollution control in non-ferrous metal smelting.

Pristine/magnesium-loaded biochar and ZVI affect rice grain arsenic speciation and cadmium accumulation through different pathways in an alkaline paddy soil.

Cadmium (Cd) and arsenic (As) co-contamination has threatened rice production and food safety. It is challenging to mitigate Cd and As contamination in rice simultaneously due to their opposite geochemical behaviors. Mg-loaded biochar with outstanding adsorption capacity for As and Cd was used for the first time to remediate Cd/As contaminated paddy soils. In addition, the effect of zero-valent iron (ZVI) on grain As speciation accumulation in alkaline paddy soils was first investigated. The effect of rice straw biochar (SC), magnesium-loaded rice straw biochar (Mg/SC), and ZVI on concentrations of Cd and As speciation in soil porewater and their accumulation in rice tissues was investigated in a pot experiment. Addition of SC, Mg/SC and ZVI to soil reduced Cd concentrations in rice grain by 46.1%, 90.3% and 100%, and inorganic As (iAs) by 35.4%, 33.1% and 29.1%, respectively, and reduced Cd concentrations in porewater by 74.3%, 96.5% and 96.2%, respectively. Reductions of 51.6% and 87.7% in porewater iAs concentrations were observed with Mg/SC and ZVI amendments, but not with SC. Dimethylarsinic acid (DMA) concentrations in porewater and grain increased by a factor of 4.9 and 3.3, respectively, with ZVI amendment. The three amendments affected grain concentrations of iAs, DMA and Cd mainly by modulating their translocation within plant and the levels of As(III), silicon, dissolved organic carbon, iron or Cd in porewater. All three amendments (SC, Mg/SC and ZVI) have the potential to simultaneously mitigate Cd and iAs accumulation in rice grain, although the pathways are different.

The role of nuclear factor erythroid 2-related factor 2 (NRF2) in arsenic toxicity.

Arsenic, a naturally occurring toxic element, manifests in various chemical forms and is widespread in the environment. Exposure to arsenic is a well-established risk factor for an elevated incidence of various cancers and chronic diseases. The crux of arsenic-mediated toxicity lies in its ability to induce oxidative stress, characterized by an unsettling imbalance between oxidants and antioxidants, accompanied by the rampant generation of reactive oxygen species and free radicals. In response to this oxidative turmoil, cells deploy their defense mechanisms, prominently featuring the redox-sensitive transcription factor known as nuclear factor erythroid 2-related factor 2 (NRF2). NRF2 stands as a primary guardian against the oxidative harm wrought by arsenic. When oxidative stress activates NRF2, it orchestrates a symphony of downstream antioxidant genes, leading to the activation of pivotal antioxidant enzymes like glutathione-S-transferase, heme oxygenase-1, and NAD(P)H: quinone oxidoreductase 1. This comprehensive review embarks on the intricate and diverse ways by which various arsenicals influence the NRF2 antioxidant pathway and its downstream targets, shedding light on their roles in defending against arsenic exposure toxic effects. It offers valuable insights into targeting NRF2 as a strategy for safeguarding against or treating the harmful and carcinogenic consequences of arsenic exposure.

Release characteristics of arsenic from sediments and its source or sink competition with phosphorus: A case of a great lake with grass-algae alternation.

The arsenic (As) release from sediments in great lakes is affected by various factors. In this study, the characteristics of As release from sediments was investigated, and the As sources and sinks with the strengths in sediments from different areas (grass-type, algae-type, and grass-algae alternation areas) in great shallow lakes (Taihu Lake, China) were analyzed, and the influence of P competition in the process of As release was also studied. The results showed that changing trend of the values of equilibrium As concentration in sediments were consistent with the regional changes (0 to 28.12 µg/L), and the sediments from algae-type areas had the higher values. The sediments from western lake and northwest lake bay were a strong As and a weak P source, and the north lake bay had the opposite trend of these two regions. Intense P source competition with As from the sediments occurred in algae-type areas. The grass-type areas had strong As and P retention capacities, indicating a sink role of sediment with high As and P sorption capacities. The degree of As and P saturation had similar trend in sediments, and the grass-type areas had the higher values, 18.3%-21.4% and 15.31%-20.34%, respectively. Contribution analysis results showed that most of As release contribution was from the bottom (30-50 cm) sediments, and the surface (0-10 cm) sediments from algae-type areas contributed more to the overlying water than other region.

Arsenic methylation and microbial communities in paddy soils under alternating anoxic and oxic conditions.

Arsenic (As) methylation in soils affects the environmental behavior of As, excessive accumulation of dimethylarsenate (DMA) in rice plants leads to straighthead disease and a serious drop in crop yield. Understanding the mobility and transformation of methylated arsenic in redox-changing paddy fields is crucial for food security. Here, soils including un-arsenic contaminated (N-As), low-arsenic (L-As), medium-arsenic (M-As), and high-arsenic (H-As) soils were incubated under continuous anoxic, continuous oxic, and consecutive anoxic/oxic treatments respectively, to profile arsenic methylating process and microbial species involved in the As cycle. Under anoxic-oxic (A-O) treatment, methylated arsenic was significantly increased once oxygen was introduced into the incubation system. The methylated arsenic concentrations were up to 2-24 times higher than those in anoxic (A), oxic (O), and oxic-anoxic (O-A) treatments, under which arsenic was methylated slightly and then decreased in all four As concentration soils. In fact, the most plentiful arsenite S-adenosylmethionine methyltransferase genes (arsM) contributed to the increase in As methylation. Proteobacteria (40.8%-62.4%), Firmicutes (3.5%-15.7%), and Desulfobacterota (5.3%-13.3%) were the major microorganisms related to this process. These microbial increased markedly and played more important roles after oxygen was introduced, indicating that they were potential keystone microbial groups for As methylation in the alternating anoxic (flooding) and oxic (drainage) environment. The novel findings provided new insights into the reoxidation-driven arsenic methylation processes and the model could be used for further risk estimation in periodically flooded paddy fields.

Morphologically controlled synthesis of MgFe-LDH using MgO and succinic acid for enhanced arsenic adsorption: Kinetics, equilibrium, and mechanism studies.

In this study, we investigated improving the performance of a layered double hydroxide (LDH) for the adsorption of As(III) and As(V) by controlling the morphology of LDH crystals. The LDH was synthesized via a simple coprecipitation method using barely soluble MgO as a precursor and succinic acid (SA) as a morphological control agent. Doping the LDH crystals with carboxylate ions (RCOO-) derived from SA caused the crystals to develop in a radial direction. This changed the pore characteristics and increased the density of active surface sites. Subsequently, SA/MgFe-LDH showed excellent affinity for As(III) and As(V) with maximum sorption densities of 2.42 and 1.60 mmol/g, respectively. By comparison, the pristine MgFe-LDH had sorption capacities of 1.56 and 1.31 mmol/g for As(III) and As(V), respectively. The LDH was effective over a wide pH range for As(III) adsorption (pH 3-8.5) and As(V) adsorption (pH 3-6.5). Using a combination of spectroscopy and sorption modeling calculations, the main sorption mechanism of As(III) and As(V) on SA/MgFe-LDH was identified as inner-sphere complexation via ligand exchange with hydroxyl group (-OH) and RCOO-. Specifically, bidentate As-Fe complexes were proposed for both As(III) and As(V) uptake, with the magnitude of formation varying with the initial As concentration. Importantly, the As-laden adsorbent had satisfactory stability in simulated real landfill leachate. These findings demonstrate that SA/MgFe-LDH exhibits considerable potential for remediation of As-contaminated water.

Arsenic(III) sequestration by terrestrial-derived soil protein: Roles of redox-active moieties and Fe(III).

Glomalin-related soil protein (GRSP) has demonstrated significant potential for water purification and remediation of heavy metals in soils; however, its redox reactivity for As(III) sequestration and the corresponding redox-active component are still poorly understood. This study investigated the photochemical properties of GRSP and its mechanism of oxidation/adsorption of As(III). The results showed that UV irradiation triggered electron transfer and the production of reactive oxygen species (ROS) in GRSP, thereby facilitating As(III) oxidation with promotion rates ranging from 43.34 % to 111.1 %. The oxidation of As(III) occurred both on the GRSP photoforming holes and in the ROS reaction from the oxygen reduction products of the photoforming electrons. OH• and H2O2 played an important role in the oxidation of As(III) by GRSP, especially under alkaline conditions. Moreover, the presence of Fe(III) in GRSP facilitated the formation of OH• and its the oxidation capacity towards As(III). The binding of As(III) to the -COOH, -OH, and -FeO groups on the GRSP surface occurred through surface complexation. Overall, these findings provided new insights into the roles of the redox-active moieties and Fe(III) on GRSP in the promoted oxidation of As(III), which would help to deepen our understanding of the migration and transformation of As(III) in soils.

Identification of key factors and mechanism determining arsenic mobilization in paddy soil-porewater-rice system.

Arsenic (As) mobilization in paddy fields poses significant health risks, necessitating a thorough understanding of the controlling factors and mechanisms to safeguard human health. We conducted a comprehensive investigation of the soil-porewater-rice system throughout the rice life cycle, focusing on monitoring arsenic distribution and porewater characteristics in typical paddy field plots. Soil pH ranged from 4.79 to 7.98, while porewater pH was weakly alkaline, varying from 7.2 to 7.47. Total arsenic content in paddy soils ranged from 6.8 to 17.2 mg/kg, with arsenic concentrations in porewater during rice growth ranging from 2.97 to 14.85 µg/L. Specifically, arsenite concentrations in porewater ranged from 0.48 to 7.91 µg/L, and arsenate concentrations ranged from 0.73 to 5.83 µg/L. Through principal component analysis (PCA) and analysis of redox factors, we identified that arsenic concentration in porewater is predominantly influenced by the interplay of reduction and desorption processes, contributing 43.5 % collectively. Specifically, the reductive dissolution of iron oxides associated with organic carbon accounted for 23.3 % of arsenic concentration dynamics in porewater. Additionally, arsenic release from the soil followed a sequence starting with nitrate reduction, followed by ferric ion reduction, and subsequently sulfate reduction. Our findings provide valuable insights into the mechanisms governing arsenic mobilization within the paddy soil-porewater-rice system. These insights could inform strategies for irrigation management aimed at mitigating arsenic toxicity and associated health risks.

[Pollution status and dietary exposure assessment of heavy metal in commercially available cereal-based complementary foods for infants and toddlers in Jiangxi Province from 2015 to 2019].

OBJECTIVE: To investigate the pollution status of lead, cadmium, total arsenic and total mercury in commercially available cereal-based complementary foods in infants and toddlers in Jiangxi Province, and to evaluate dietary exposure and their potential health risks. METHODS: A total of 648 samples of cereal-based complementary foods in for infants and toddlers were randomly collected in circulation in Jiangxi Province, the contents of lead and cadmium were determined by graphite furnace atomic absorption spectrophotometry, and total arsenic and mercury were determined by atomic fluorescence spectrometry. The dietary exposure of lead, cadmium, total arsenic and total mercury was calculated by point estimate model. Margin of exposure(MOE) and tolerable intake(TI) were used to assess the health risks. RESULTS: The average values of lead, cadmium, total arsenic and total mercury in cereal-based complementary foods in Jiangxi Province were 0.039, 0.062, 0.080 and 0.0016 mg/kg, the average detection rates are 81.2%, 94.6%, 89.4% and 73.4%. There were no exceedance samples for lead, total arsenic and total mercury. There were partial exceedances of the cadmium standard in 2015-2018, and cadmium exceedances improved significantly in 2019. The MOE values of lead and total arsenic were greater than 1 in different years, total mercury exposure accounted for 0.71%-2.13% of the provisional tolerable weekly intake(PTWI), cadmium exposure accounted for 43.5%-62.3% of the provisional tolerable monthly intake(PTMI) in 2015-2018, decreasing to7.91%-9.23% of the PTMI in 2019. CONCLUSION: Lead, total arsenic and total mercury contamination in cereal-based complementary foods in Jiangxi Province monitored from 2015 to 2019 was relatively light, cadmium contamination has improved significantly and the health risk of heavy metal intake through cereal-based complementary foods for infants and young children was at an acceptable level.

[NRF2 mediated redox stress in arsenic induced human keratinocytes malignant transformation].

OBJECTIVE: To explore the role of nuclear transcription factor E2-related factor 2(NRF2)-mediated reductive stress in arsenite induced malignant transformation in human keratinocytes. METHODS: HaCaT cells and fluorescent labeled mitochondrial glutathione HaCaT cells(Mito-Grx1-roGFP2 HaCaT) were cultured to 35 passages in medium containing 0.0 and 1.0 µmol/L NaAsO_2 to establish a model of malignant transformation of cells. Cellular and mitochondrial reduced glutathione/oxidized glutathione(GSH/GSSG) and reduced coenzyme II/oxidized coenzyme II(NADPH/NADP~+) ratios were measured in HaCaT cells. Cell doubling time, cell migration ability, soft agar clone formation ability and GSH/GSSG at different times in the 0 passage, the early stage(1st, 7th and 14th passages) and later stage(21st, 28th and 35th passages) were measured in Mito-Grx1-roGFP2 HaCaT cells. NaAsO_2 induced malignant transformation cells were transfected with NRF2 siRNA, and detected the expression level of NRF2 and the redox-related indexes and malignant transformation indexes. RESULTS: Compared with the control group, the GSH/GSSG ratio in 1.0 µmol/L NaAsO_2 treated HaCaT cells significantly decreased in the 1st and 7th generations, but significantly increased after the 21st generation, and the NADPH/NADP~+ ratio significantly increased in the 1st, 14th, 21st, 28th and 35th generations; The levels of GSH/GSSG in mitochondria significantly increased from 1st to 35th generation, and the levels of NADPH/NADP~+ in mitochondria significantly increased at 1st, 7th, 21st, 28th and 35th generation. After continuous treatment of Mito-Grx1-roGFP2 HaCaT cells with 0.0 or 1.0 µmol/L NaAsO_2 to 35 passages, the doubling time of cells treated with 1.0 µmol/L NaAsO_2 was significantly shortened, the cell migration rate was increased greatly, and more clones with larger volumes than the control cells formed. The GSH/GSSG ratio in mitochondria of Mito-Grx1-roGFP2 HaCaT cells showed a significant decrease in the 1st generation and increased from the 7th generation onwards(all P<0.05). After transfection of NaAsO_2 treated cells with NRF2 siRNA, the levels of hydrogen peroxide and superoxide increased compared with the siRNA controls. The levels of cell and mitochondrial NADPH/NADP~+ and GSH/GSSG decreased and the level of mitochondrial GSH/GSSG in Mito-Grx1-roGFP2 HaCaT cells decreased. Cell doubling time increased, cell migration rate and soft agar clone formation ability decreased(all P<0.05). The malignant phenotype was reversed. CONCLUSION: In the early stage(1st, 7th and 14th passages) of NaAsO_2 treated HaCaT cells, oxidative stress occurred with continuous high NRF2 expression. Later(21st, 28th and 35th passages), NRF2 induced reductive stress, leading to malignant transformation.

Seasonal and spatial variations of arsenic and its species in particulate matter in an urban environment of Brno, Czech Republic.

The present paper deals with an analysis of total arsenic concentration using ICP-MS/MS and an analysis of concentration of several arsenic species, arsenite (AsIII), arsenate (AsV), monomethylarsonate (MMA), dimethylarsenite (DMA), and trimethylarsine oxide (TMAO), using HPLC-ICP-MS/MS in the PM10 fraction of airborne urban aerosol. The samples were collected during two campaigns, in the autumn of 2022 and in the winter of 2023, at three locations within the central European city of Brno, with the aim to evaluate the seasonal and spatial variations in the PM10 composition. The results confirmed only the seasonal variability in the content of the methylated arsenic species in PM10 influenced by biomethylation processes. To gain better understanding of the possible arsenic origin, a supplementary analysis of the total arsenic concentrations was performed in samples of different size fractions of particulate matter collected using ELPI + . Local emissions, including industrial activities and heating during the winter season, were suggested as the most likely predominant source contributing to the total As content in PM10.

High arsenic contamination in the breast milk of mothers inhabiting the Gangetic plains of Bihar: a major health risk to infants.

Groundwater arsenic poisoning has posed serious health hazards in the exposed population. The objective of the study is to evaluate the arsenic ingestion from breastmilk among pediatric population in Bihar. In the present study, the total women selected were n = 513. Out of which n = 378 women after consent provided their breastmilk for the study, n = 58 subjects were non-lactating but had some type of disease in them and n = 77 subjects denied for the breastmilk sample. Hence, they were selected for the women health study. In addition, urine samples from n = 184 infants' urine were collected for human arsenic exposure study. The study reveals that the arsenic content in the exposed women (in 55%) was significantly high in the breast milk against the WHO permissible limit 0.64 µg/L followed by their urine and blood samples as biological marker. Moreover, the child's urine also had arsenic content greater than the permissible limit (< 50 µg/L) in 67% of the studied children from the arsenic exposed regions. Concerningly, the rate at which arsenic is eliminated from an infant's body via urine in real time was only 50%. This arsenic exposure to young infants has caused potential risks and future health implications. Moreover, the arsenic content was also very high in the analyzed staple food samples such as rice, wheat and potato which is the major cause for arsenic contamination in breastmilk. The study advocates for prompt action to address the issue and implement stringent legislative measures in order to mitigate and eradicate this pressing problem that has implications for future generations.

Pseudochrobactrum asaccharolyticum mitigates arsenic induced oxidative stress of maize plant by enhancing water status and antioxidant defense system.

BACKGROUND: Oxidative stress mediated by reactive oxygen species (ROS) is a common denominator in arsenic toxicity. Arsenic stress in soil affects the water absorption, decrease stomatal conductance, reduction in osmotic, and leaf water potential, which restrict water uptake and osmotic stress in plants. Arsenic-induced osmotic stress triggers the overproduction of ROS, which causes a number of germination, physiological, biochemical, and antioxidant alterations. Antioxidants with potential to reduce ROS levels ameliorate the arsenic-induced lesions. Plant growth promoting rhizobacteria (PGPR) increase the total soluble sugars and proline, which scavenging OH radicals thereby prevent the oxidative damages cause by ROS. The main objective of this study was to evaluate the potential role of Arsenic resistant PGPR in growth of maize by mitigating arsenic stress. METHODOLOGY: Arsenic tolerant PGPR strain MD3 (Pseudochrobactrum asaccharolyticum) was used to dismiss the 'As' induced oxidative stress in maize grown at concentrations of 50 and 100 mg/kg. Previously isolated arsenic tolerant bacterial strain MD3 "Pseudochrobactrum asaccharolyticum was used for this experiment. Further, growth promoting potential of MD3 was done by germination and physio-biochemical analysis of maize seeds. Experimental units were arranged in Completely Randomized Design (CRD). A total of 6 sets of treatments viz., control, arsenic treated (50 & 100 mg/kg), bacterial inoculated (MD3), and arsenic stress plus bacterial inoculated with three replicates were used for Petri plates and pot experiments. After treating with this MD3 strain, seeds of corn were grown in pots filled with or without 50 mg/kg and 100 mg/kg sodium arsenate. RESULTS: The plants under arsenic stress (100 mg/kg) decreased the osmotic potential (0.8 MPa) as compared to control indicated the osmotic stress, which caused the reduction in growth, physiological parameters, proline accumulation, alteration in antioxidant enzymes (Superoxide dismutase-SOD, catalase-CAT, peroxidase-POD), increased MDA content, and H2O2 in maize plants. As-tolerant Pseudochrobactrum asaccharolyticum improved the plant growth by reducing the oxidation stress and antioxidant enzymes by proline accumulation. PCA analysis revealed that all six treatments scattered differently across the PC1 and PC2, having 85.51% and 9.72% data variance, respectively. This indicating the efficiency of As-tolerant strains. The heatmap supported the As-tolerant strains were positively correlated with growth parameters and physiological activities of the maize plants. CONCLUSION: This study concluded that Pseudochrobactrum asaccharolyticum reduced the 'As' toxicity in maize plant through the augmentation of the antioxidant defense system. Thus, MD3 (Pseudochrobactrum asaccharolyticum) strain can be considered as bio-fertilizer.

Facilitating inorganic arsenic speciation and quantification in waters: Polymer inclusion membrane preconcentration and X-ray fluorescence detection.

BACKGROUND: Arsenic, classified as a priority pollutant and human carcinogen by the IARC, is subject to stringent regulatory limits in food and water. Among various arsenic species found in water samples, arsenite (As(III)) is identified as the most toxic form. Given the limitations of conventional spectroscopic techniques in speciation analysis, there is a crucial need for innovative and sustainable methodologies that enable arsenic speciation. Simplifying these methodologies is essential for widespread applicability and effective environmental monitoring. RESULTS: This study proposes a simple and cost-effective analytical methodology for speciating inorganic arsenic in water samples. The method involves extracting As(III) into a polymer inclusion membrane (PIM) containing the extractant Cyanex 301 (bis(2,4,4-trimethylpentyl) dithiophosphinic acid), followed by analysis using energy dispersive X-ray fluorescence (EDXRF) spectrometry. The concentration of arsenate was measured after a reduction step using a thiosulfate/iodide mixture. This simple methodology allows a limit of quantification for trivalent arsenic (2 µg L-1), which is well below the World Health Organization's recommended maximum permissible level of As in drinking water (10 µg L-1). The method that is developed allows the determination of As at trace levels in waters with naturally occurring arsenic. SIGNIFICANCE AND NOVELTY: This study represents a significant advance in the field, providing a novel and efficient methodology for arsenic speciation analysis in water samples. By combining the advantages of polymer inclusion membrane (PIM) extraction with energy dispersive X-ray fluorescence (EDXRF) spectrometry, this study offers a cost-effective and environmentally friendly approach to address the critical issue of arsenic contamination in water sources, thereby contributing to enhanced environmental monitoring and public health protection.

Critical assessment of recent advancements in chitosan-functionalized iron and geopolymer-based adsorbents for the selective removal of arsenic from water.

Inorganic arsenic (As), a known carcinogen and major contaminant in drinking water, affects over 140 million people globally, with levels exceeding the World Health Organization's (WHO) guidelines of 10 µg L-1. Developing innovative technologies for effluent handling and decontaminating polluted water is critical. This paper summarizes the fundamental characteristics of chitosan-embedded composites for As adsorption from water. The primary challenge in selectively removing As ions is the presence of phosphate, which is chemically similar to As(V). This study evaluates and summarizes innovative As adsorbents based on chitosan and its composite modifications, focusing on factors influencing their adsorption affinity. The kinetics, isotherms, column models, and thermodynamic aspects of the sorption processes were also explored. Finally, the adsorption process and implications of functionalized chitosan for wastewater treatment were analyzed. There have been minimal developments in water disinfection using metal-biopolymer composites for environmental purposes. This field of study offers numerous research opportunities to expand the use of biopolymer composites as detoxifying materials and to gain deeper insights into the foundations of biopolymer composite adsorbents, which merit further investigation to enhance adsorbent stability.

Exploring native arsenic (As)-resistant bacteria: unveiling multifaceted mechanisms for plant growth promotion under As stress.

AIMS: This study explores the plant growth-promoting effect (PGPE) and potential mechanisms of the arsenic (As)-resistant bacterium Flavobacterium sp. A9 (A9 hereafter). METHODS AND RESULTS: The influences of A9 on the growth of Arabidopsis thaliana, lettuce, and Brassica napus under As(V) stress were investigated. Additionally, a metabolome analysis was conducted to unravel the underlying mechanisms that facilitate PGPE. Results revealed that A9 significantly enhanced the fresh weight of Arabidopsis seedlings by 62.6%-135.4% under As(V) stress. A9 significantly increased root length (19.4%), phosphorus (25.28%), chlorophyll content (59%), pod number (24.42%), and weight (18.88%), while decreasing As content (48.33%, P ≤ .05) and oxidative stress of Arabidopsis. It also significantly promoted the growth of lettuce and B. napus under As(V) stress. A9 demonstrated the capability to produce ≥31 beneficial substances contributing to plant growth promotion (e.g. gibberellic acid), stress tolerance (e.g. thiamine), and reduced As accumulation (e.g. siderophores). CONCLUSIONS: A9 significantly promoted the plant growth under As stress and decreased As accumulation by decreasing oxidative stress and releasing beneficial compounds.