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The timing and efficiency of arsenic (As) accumulation is crucial for using the hyperaccumulator P. vittata in remediation of As-contaminated soils. In this study, through an innovative microXRF-based approach, using a new "pinna powder" sampling method, we monitored As accumulation over time in fronds of individual P. vittata plants grown in the greenhouse and in the field on two natural soils, with high (750 mg/kg) and moderate (58.4 mg/kg) As concentrations. Results, validated by multivariant statistical analysis show that the peak of As occurs on both soils at 45/60 days and at 100/120 days in greenhouse and field grown plants, respectively. Furthermore, in field trials, the timing of As accumulation in both soils was similar during the first autumn-winter and the second spring-summer phytoextraction cycle. After the two cycles, soil As content was reduced by 70.4% in the high-As soil and 26.4% in the moderate one. Moreover, candidate genes involved in As hyperaccumulation -the arsenite antiporter PvACR3 , the As (V)-reductases Pv2.5-8 and the organic cation transporter PvOCT4 - are expressed in response to As in field-grown plants with similar kinetics in both soils. In conclusion, we established by this innovative technique, the timing of maximum As accumulation that is linked to the intrinsic hyperaccumulation mechanism and represents a highly powerful tool to set up the duration of phytoextraction cycles. [Display omitted] • Development of a microXRF-based technique to monitor As accumulation in P. vittata. • Field-grown ferns at high and moderate As show an As accumulation peak between 100/120 days. • PvACR3, Pv2.5.8 and PvOCT4 expression in field-grown ferns responds to As in soils. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of post-calcination on the charge properties and active sites of Mg/Al layered double hydroxide-decorated spent coffee ground biochars (LDH MgAl @SCGB) governing adsorption behaviors and mechanisms of arsenic (AsV) and antimony (SbV) anions from aqueous phases. Post-calcinated LDH MgAl @SCGB (PLDH MgAl @SCGB) exhibited higher adsorption capacities for AsV and SbV compared to spent coffee ground biochars (SCGB) and LDH MgAl @SCGB as post-calcination of LDH MgAl @SCGB enhanced the charge properties (surface zeta potential at pH 7.0: SCGB = −21.8 mV, LDH MgAl @SCGB = 28.5 mV, and PLDH MgAl @SCGB = 34.4 mV) and increased active sites by eliminating the anions (i.e., Cl− ions) and water molecules at its interlayers. The calculated kinetic, intra-particle diffusion, and isotherm parameters indicated that the chemisorption and intra-particle diffusion were mainly responsible for the adsorption of AsV and SbV by SCGB, LDH MgAl @SCGB, and PLDH MgAl @SCGB. Moreover, post-calcination of LDH MgAl @SCGB enhanced its selectivity toward AsV and SbV by reinforcing the electrostatic surface complexation via its improvement of charge properties. Since PLDH MgAl @SCGB exhibited the excellent reusability for the adsorption of AsV (reuse efficiency >63.6%) and SbV (reuse efficiency >52.1%), it can be concluded that post-calcination of LDH MgAl @SCGB is a promising method for improving the adsorption capacities for AsV and SbV in real water matrices. [Display omitted] • Post-calcination effectively removes interlayer anions of LDH MgAl @SCGB. • Increased active sites of PLDH MgAl @SCGB enhance electrostatic surface complexation. • PLDH MgAl @SCGB exhibits highest adsorption capacities of AsV and SbV. • PLDH MgAl @SCGB has excellent reusability for the adsorption of AsV and SbV. [ABSTRACT FROM AUTHOR]

Understanding the interaction between heavy metals and soil microbiomes is essential for maintaining ecosystem health and functionality in the face of persistent human-induced challenges. This study investigated the complex relationships between heavy metal contamination and the functional characteristics of soil microbial communities in the tidal soils of Hangzhou Bay, a region experiencing substantial environmental pressure due to its proximity to densely populated and industrialized regions. The north-shore sampling site showed moderate contaminations (mg/kg) of total arsenic (16.61 ± 1.13), cadmium (0.3 ± 0.05), copper (31.28 ± 1.23), nickel (37.44 ± 2.74), lead (34.29 ± 5.99), and zinc (120.8 ± 5.96), which are 1.29–2.94 times higher than the geochemical background values in Hangzhou Bay and adjacent areas. In contrast, the south-shore sampling site showed slightly higher levels of total arsenic (13.76 ± 1.35) and cadmium (0.13 ± 0.02) than the background values. Utilizing metagenomic sequencing, we decoded microbial functional genes essential for nitrogen, phosphorus, sulfur, and methane biogeochemical cycles. Although soil available nickel content was relatively low at 1 mg/kg, it exhibited strong associations with diverse microbial genes and biogeochemical pathways. Four key genes— hxlB , glpX , opd , and phny —emerged as pivotal players in the interactions with available nickel, suggesting the adaptability of microbial metabolic responses to heavy metal. Additionally, microbial genera such as Gemmatimonas and Ilumatobacter , which harbored diverse functional genes, demonstrated potential interactions with soil nickel. These findings highlight the importance of understanding heavy metal-soil microbiome dynamics for effective environmental management strategies in the tidal soils of Hangzhou Bay, with the goal of preserving ecosystem health and functionality amidst ongoing anthropogenic challenges. [Display omitted] • Heavy metals affect microbial genes involved in biogeochemical cycles in the tidal soils. • Soil available Ni highlights its interactions with soil microbiome. • Gemmatimonas and Ilumatobacter genera harbor diverse functional genes interacting with soil Ni. [ABSTRACT FROM AUTHOR]

Arsenic (As) and polycyclic aromatic hydrocarbons (PAHs) are highly toxic, carcinogenic and teratogenic, and are commonly found in soils of industrial sites such as coking plants. They exert environmental stresses on soil microorganisms, but their compounding effects have not been systematically studied. Exploring the effects of compound contamination on microbial communities, species and genes is important for revealing the ecological damage caused by compound contamination and offering scientific insights into soil remediation strategies. In this study, we selected soil samples from 0 to 100 cm depth of a coking site with As, PAHs and compound contamination. We investigated the compound effects of As and PAHs on microbial communities by combining high-throughput sequencing, metagenomic sequencing and genome assembly. Compared with single contamination, compound contamination reduced the microbial community diversity by 10.68%–12.07% and reduced the community richness by 8.39%–18.61%. The compound contamination decreased 32.41%–46.02% of microbial PAHs metabolic gene abundance, 11.36%–19.25% of cell membrane transport gene abundance and 12.62%–57.77% of cell motility gene abundance. Xanthobacteraceae , the biomarker for compound contaminated soils, harbors arsenic reduction genes and PAHs degradation pathways of naphthalene, benzo [a]pyrene, fluorene, anthracene, and phenanthrene. Its broad metabolic capabilities, encompassing sulfur metabolism and quorum sensing, facilitate the acquisition of energy and nutrients, thereby conferring ecological niche advantages in compound contaminated environments. This study underscores the significant impacts of As and PAHs on the composition and function of microbial communities, thereby enriching our understanding of their combined effects and providing insights for the remediation of compound contaminated sites. [Display omitted] • As And PAHs compound contamination simplifies soil microbial communities. • Compound contamination reduces the abundance of key functional genes in microbial communities. • Representative species Xanthobacteraceae possesses As and PAHs metabolism functions. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) and arsenic (As) have contrasting biogeochemical behaviors in paddy soil, which posed an obstacle for reducing their accumulation in rice (Oryza sativa L.) simultaneously. In this study, selenate exhibited a more effective ability than selenite on simultaneous alleviation of Cd and As accumulation in rice under Cd-As co-exposure, and the mechanisms need to be further investigated. The results showed that selenate significantly decreased the root Cd and As contents by 59%–83% and 43%–72% compared to Cd-As compound exposure, respectively. Correspondingly, it significantly down-regulated the expression of uptake-related genes OsNramp5 (87.1%) and OsLsi1 (95.5%) in rice roots. Decreases in Cd (64.5%) and As (16.2%) contents in shoots were also found after selenate addition. Moreover, selenate may promoted the reduction of As(V) to As(Ⅲ) and As(III) efflux to the external medium, resulting in decreased As accumulation and As(Ⅲ) proportion in rice shoots and roots. In addition, selenate could promote the binding of Cd (by 14%–24%) and As (by 9%–15%) in the cell wall, and significantly reduced the oxidative stress by elevating levels of antioxidant enzymes (by 10%–105%) and thiol compounds (by 6%–210%). Additionally, selenate significantly down-regulated the expression of OsNramp1 (49.3%) and OsLsi2 (82.1%) associated with Cd and As transport in rice. These findings suggest selenate has the potential to be an effective material for the simultaneous reduction of Cd and As accumulation in rice under Cd-As co-contamination. [Display omitted] • Cd-As co-stress inhibited their accumulation compared to Cd/As alone stress. • Selenate reduced Cd and As root uptake more than selenite under Cd-As co-exposure. • Selenate down-regulated the expressions of OsNramp5 , OsLsi1 , OsNramp1 and OsLsi2. • Selenate promoted the sequestration of Cd and As in the cell wall. • Selenate decreased As accumulation and As(Ⅲ) proportion in rice shoots and roots. [ABSTRACT FROM AUTHOR]

Arsenic (As) can accumulate in edible plant parts and thus pose a serious threat to human health. Identifying the contributions of various factors to soil available As is crucial for evaluating environmental risks. However, research quantitatively assessing the importance of soil properties on available As is scarce. In this study, we utilized 442 datasets covering total As, available As, and properties of farmland soils. The five machine learning models were employed to predict soil available As content, and the model with the best predictive performance was selected to calculate the importance of soil properties on available As and interpret the model results. The Random Forest model exhibited the best predictive performance, with R2 for the test set of dryland and paddy fields being 0.83 and 0.82 respectively, while also outperforming other machine learning models in terms of accuracy. Concurrently, evaluating the contribution of soil properties to soil available As revealed that increases in soil total arsenic, pH, organic matter (OM), and cation exchange capacity (CEC) led to higher soil available As content. Among these factors, soil total As had the greatest impact, followed by CEC. The influence of pH on soil available As was greater in dryland compared to OM, while in paddy fields, it was smaller than OM (p < 0.01). Sensitivity analysis results indicated that reducing soil total As content had the greatest effect on available As. In both dryland and paddy field soils, reducing soil total As had the most pronounced effect on available As, leading to reductions of 10.09% and 8.48%, respectively. Therefore, prioritizing the regulation of soil total As and CEC is crucial in As contamination management practices to alter As availability in farmland soils. [Display omitted] • Random forest model can effectively predict soil available As and evaluate factor importance. • Soil total As has the greatest positive impact, followed by CEC. • pH influences soil available As more in dryland than OM, but less in paddy field. • Regulate soil total As first, then CEC to reduce available As in farmland soil. [ABSTRACT FROM AUTHOR]

A holistic understanding of the chemical recovery of lakes from arsenic (As) pollution requires consideration of within-lake biogeochemical cycling of As and processes occurring in the surrounding catchment. This study used a watershed mass balance approach, complemented by experimental sediment incubations, to assess the mobility and transport of As within a subarctic watershed (155 km2) impacted by more than 60 years of atmospheric mining emissions. The period of record spanned a transition from drought to high streamflow between September 2017 and September 2019, which yielded insights into the interacting effects of hydrology and within-lake biogeochemical cycling of As. Internal loading of As from contaminated lake sediments (25–46 kg As year−1) and contributions from terrestrial sources (16–56 kg As yr−1) continue to negatively impact lake water quality (19–144 μg As L−1), but the relative importance of these loads varies seasonally and inter-annually in response to changing hydrological conditions. Wet conditions resulted in greater transport of As from terrestrial reservoirs and upstream areas, shorter lake water retention time, and increased the downstream export of As. During dry periods, the lake was disconnected from the surrounding watershed resulting in limited terrestrial contributions and longer lake water residence time, which delayed recovery due to the greater relative influence of internal loading from contaminated sediments. This study highlights that changing hydroclimatic regimes will alter trajectories of chemical recovery for arsenic impacted lakes through the coupling of within-lake and watershed transport processes. [Display omitted] • A watershed mass balance was used to assess the transport of As within a subarctic watershed. • Measurements spanned a period of drought to high streamflow conditions. • Higher lake water As in dry periods, due to greater influence of internal sediment loading. • Lower lake water As under high streamflow conditions with increase in watershed connectivity. • Changing hydroclimatic regimes will alter trajectory of recovery for As impacted lakes. [ABSTRACT FROM AUTHOR]

Schwertmannite (Sch) holds a great promise as an iron material for remediating Arsenic (As)-contaminated paddy soils, due to its extremely high immobilization capacities for both arsenate [As(V)] and arsenite [As(III)]. However, there is still limited knowledge on the mineral phase transformation of this metastable iron-oxyhydroxysulfate mineral in paddy soils, particularly under different water management regimes including aerobic, intermittent flooding, and continuous flooding, and how its phase transformation impacts the migration of As in paddy soils. In this study, a membrane coated with schwertmannite was first developed to directly reflect the phase transformation of bulk schwertmannite applied to paddy soils. A soil incubation experiment was then conducted to investigate the mineral phase transformation of schwertmannite in paddy soils under different water management regimes and its impact on the migration of As in paddy soil. Our findings revealed that schwertmannite can persist in the paddy soil for 90 days in the aerobic group, whereas in the continuous flooding and intermittent flooding groups, schwertmannite transformed into goethite, with the degree or rate of mineral phase transformation being 5% Sch >1% Sch > control. These results indicated that water management practices and the amount of schwertmannite applied were the primary factors determining the occurrence and degree of mineral transformation of schwertmannite in paddy soil. Moreover, despite undergoing phase transformation, schwertmannite still significantly reduced the porewater As (As(III) and As(V)), and facilitated the transfer of non-specifically adsorbed As (F1) and specifically adsorbed As (F2) to amorphous iron oxide-bound As (F3), effectively reducing the bioavailability of soil As. These findings contribute to a better understanding of the mineralogical transformation of schwertmannite in paddy soils and the impact of mineral phase transformation on the retention of As in soil, which carry important implications for the application of schwertmannite in remediating As-contaminated paddy soils. [Display omitted] • A novel method was developed to reflect schwertmannite transformation in soil. • Water management controlled schwertmannite transformation in paddy soil. • Schwertmannite exhibited a strong stability under aerobic conditions. • Schwertmannite transformed to goethite under continuous or intermittent flooding. • Schwertmannite reduced As mobility despite undergoing phase transformation. [ABSTRACT FROM AUTHOR]

To explore the characteristics and evaluate the risk of heavy metals in groundwater at a typical smelter-contaminated site, this study focuses on a representative a historical arsenic smelting plant in Southwest China, where the primary historical products were metallic arsenic (∼1000 tons/year) and arsenic trioxide (∼2000 ton/year). The results demonstrated As and Pb as the main pollutants in soil, and As and Cd as main pollutants in groundwater through soil profiling and quarterly groundwater analysis. The maximum As and Pb in the surface soil were 76800 and 2290 mg/kg, respectively, with As vertically infiltrating the deep gravel–sand layer (18–20 m). The groundwater pollution distribution progressively increased along flow direction, influenced by seasonal surface runoff and infiltration fluctuations. The groundwater pollutant concentrations during the dry season notably surpassed those during the wet season, with maximum As and Cd concentrations of 111.64 mg/L and 19.85 μg/L during the dry season, respectively. Furthermore, the analytic hierarchy process (AHP) was applied to evaluate the comprehensive risk of contaminated-site across pollution source load, regional groundwater intrinsic vulnerability, and evaluation of nearby sensitive receptors. The results revealed that the carcinogenic risk of lead in surface soil was moderate to high, while arsenic posed a high carcinogenic risk, contributing to an overall carcinogenic risk proportion of 89.6% in surface soil. Exposure through groundwater intake was identified as the primary pathway, with carcinogenic and noncarcinogenic risks exceeding those through skin contact. The final weights result demonstrated that the principal risk factors are the intrinsic arsenic load and protective target characteristics of regional groundwater at this site. This study provides a reference for comprehensive assessments of similarly contaminated industrial and smelting sites. [Display omitted] • The main soil–groundwater pollutants at the smelting site are As, Pb, and Cd. • The vertical distribution of As and Pb in soil shows surface aggregation. • The flow field and seasonal rainfall affected As distribution in groundwater. • As Loads and protection goals determined the comprehensive risk of groundwater. [ABSTRACT FROM AUTHOR]

Arsenic is a hazardous element found in water sources, and removing it is crucial for ensuring a safe environment and water quality. Iron-based metal oxides efficiently remove arsenic; however, their small particle sizes make separation from water difficult after arsenic removal. Furthermore, the growing global issue of polymer waste further complicates environmental concerns. Combining three-dimensional (3D) printing and adsorption technology by incorporating nanosized functional materials into supporting polymers offers a potential solution to address both challenges. In this study, we developed a 3D-printed adsorption material through the incorporation of synthesized Fe–Ni bimetallic particles into a supporting polymer using selective laser sintering (SLS) technology. This adsorbent's properties were examined through scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and zeta potential. Furthermore, its performance in removing As(III) and As(V), even at trace levels, was assessed under varied conditions. The 3D-printed adsorbent demonstrated excellent removal of As(III) at pH 6, and As(V) at pH 4, lowering their concentration below 10 μg/L, thereby adhering to the limit established by the World Health Organization (WHO). Both As(III) and As(V) fitted the Freundlich isotherm and pseudo-second-order model, suggesting potential heterogeneous and chemisorption processes. FT-IR indicated that the exchange of the –OH group of Fe–OH with oxyanions of As(III) and As(V) could be the adsorption mechanism. Additionally, thermodynamic evaluation unveiled an endothermic and non-spontaneous adsorption reaction. The 3D-printed adsorbent exhibited excellent reusability across recurring adsorption cycles. The combination of SLS 3D printing with Fe–Ni bimetallic particles produces structures that retain their functionality in removing both arsenic species present in water. This indicates the potential of the 3D-printed adsorbent for effective treatment of arsenic-contaminated water, offering remedies to challenges like handling small particle sizes, mitigating polymer waste, and addressing environmental concerns. [Display omitted] • 3D-FeNi adsorbent was successfully designed using selective laser sintering. • 3D-FeNi adsorbent efficiently removes arsenic <10 μg/L, meeting WHO limits. • Good reusability up to five cycles was achieved with the 3D-printed adsorbent. [ABSTRACT FROM AUTHOR]

The effects of different dissolved organic phosphorus (DOP) associated with distinct iron conditions (iron deficient (dFe), ferric ions (Fe3+), and colloidal iron (CFe)) on algal growth and arsenate (As(V)) metabolism were systematically evaluated and compared in Microcystis aeruginosa. Two chemical forms of DOP (D-glucose-6-phosphate (GP) and phytic acid (PA)), as well as dissolved inorganic phosphorus (DIP), were employed as distinct phosphorus environments. The results revealed that As(V) metabolism of M. aeruginosa was more influenced by different phosphorus forms than by different iron conditions. Conversely, the release of microcystins in the media was found to be significantly more affected by the different phosphorus forms than by the iron conditions. Moreover, DOP was observed to promote arsenic (As) biotransformation, particularly the efflux of methylated As from a single algal cell, whereas DIP was found to primarily facilitate As(V) accumulation in algae. The total As metabolism amount per algal cell under PA was observed to be five times that observed under DIP and GP. The influence of iron conditions on the synthesis of algal metabolites was notable, as evidenced by the metabolites identified in algae of aliphatic (δ 1.28–1.68), humic acid-like and aromatic protein-like substances through 1H-NMR spectra and three-dimensional excitation-emission matrix fluorescence spectroscopy analysis. This impact was particularly notable at Fe3+ conditions, due to the role of Fe3+ as a micronutrient with highly bioavailable forms, which enhanced the synthesis of organic compounds in algae and promoted algal growth. Consequently, Fe3+ could inhibit As accumulation under DIP but promote it under DOP. The obtained results facilitate a more comprehensive understanding of the combined role of different phosphorus forms and iron conditions in algal bloom outbreaks and As(V) metabolism. [Display omitted] • The effect of different iron conditions on algal growth was greater than that of P forms. • More intracellular metabolites were observed at Fe3+ than dFe and CFe using 1H-NMR spectra. • MCs release was found to be more affected by the different forms of P than Fe. • Fe3+ could facilitate As(V) accumulation under dissolved organic phosphorus. • Fe3+ was conducive to the reduction of As(V) by algal cells. [ABSTRACT FROM AUTHOR]

Groundwater pollution from valley type landfills is concerning, and natural attenuation by contaminants is increasingly relied upon. However, the reliability of natural attenuation in such complex sites has been called into question due to incomplete understanding of their attenuation mechanisms. Therefore, we conducted field investigations, monitoring analyses, mathematical statistics, and machine learning techniques to elucidate the natural attenuation mechanisms of pollutants within bedrock fissures at a prototypical valley type landfill located in the east Yanshan Mountains, China. Our results indicate that 50% of the monitored indicators showed extreme pollution in bedrock fissure aquifers, due to seepage from the valley type landfill site. Ammonia nitrogen, arsenic, cadmium, lead, iron, manganese, and mercury were among the contaminants that could pose serious risks to human health. Pollutant concentrations in bedrock fissure aquifers were lower during the rainy season compared to the dry season as the aquifer was rapidly recharged by strong rainfall runoff. The initial concentration of bedrock fissure water generally increased during the flow through the landfill. However, significant natural attenuation of total dissolved solids, oxygen consumption, ammonia, cadmium, and lead occurred after passing through the landfill (p < 0.05), with attenuation coefficients of 0.0041 m-1, 2.56 × E−5 m −2, 4.18 × E−5 m −2、0.0015 m-0.99, and 6.83 × E−33 m −12.49, respectively. The driving mechanisms for natural attenuation include physical migration, leaching, microbiological degradation, and adsorption, primarily occurring within 600–650 m downstream of the landfill boundary. This study makes fundamental contribution to the understanding of the migration and natural attenuation process of leachate pollutants in bedrock fissure aquifer, which will provide a scientific basis for implementation of natural attenuation strategies in complex site remediation. Future research should examine more precise evidence of natural attenuation feasibility in complex sites in conjunction with monitoring networks. [Display omitted] • Leachate leaking from the valley type landfill hazardously pollutes groundwater. • Dilution during the rainy season improves water quality in aquifers. • Bedrock fissure water is rapidly attenuated by both biotic and abiotic effects. • Natural attenuation helps control groundwater pollution from valley type landfills. [ABSTRACT FROM AUTHOR]

Industrial and urban activities are major contributors to metal contamination in coastal systems, often impacting the physiology, distribution and diversity of marine invertebrates. This study assessed metal contaminations in sediments, seawater, algae and invertebrates across four armoured systems (harbours) and two natural sites along the south coast of South Africa. Bioaccumulation factors such as Biosediment (BSAF), Biowater (BWAF), Bioaccumulation (BAF) and bioremediation of metals by invertebrate bioindicators were also determined. Spatial variation in metal concentrations were observed, however, bioaccumulation of metals was site and species-specific. Invertebrates bioaccumulated higher metal concentrations in armoured than natural sites, with filter feeders exhibiting higher concentrations than grazers. Among filter feeders, Octomeris angulosa and Crassostrea gigas bioaccumulated elevated aluminium (Al), arsenic (As), chromium (Cr), zinc (Zn) and copper (Cu), while, Perna perna accumulated elevated nickel (Ni), cadmium (Cd) and lead (Pb). Among grazers, Siphonaria serrata and Scutellastra longicosta bioaccumulated elevated Al, Cr, Cd, cobalt (Co), Cu, Ni and Zn. Bioaccumulation factors indicated that (As, Ni, Zn) were bioaccumulated by algae, and invertebrates from sediment (BSAF>1) and from seawater (BWAF>1). Additionally, invertebrates bioaccumulated metals from their prey item, algae as indicated by (BAF>1). Arsenic Cd and Pb in invertebrates were above the maximum limit set for human consumption by various regulatory bodies. Our findings underscore the significant role of coastal invertebrates in bioaccumulating and bioremediating metals, suggesting a natural mechanism for water quality enhancement, especially in urbanised coastal areas. [Display omitted] • Metal pollution in urban coastal systems is of great concern due to metals widespread distribution. • Biowater and Biosediment Accumulation Factors are useful models for metal bioaccumulation and bioremediation assessment. • Bivalve and gastropods proved to be suitable bioindicators and bioremediators of metal pollution. [ABSTRACT FROM AUTHOR]

Bacteria-assisted phytoremediation uses bacteria to promote plant health and improve its ability to remediate toxic heavy metals like Arsenic (As). Here, we isolated rhizobacteria and identified them as Bacillus subtilis strain IU31 using 16S rDNA sequencing. IU31 showed phosphate solubilization potential on Pikovskaya agar medium and produced siderophores, which were detected on Chromium Azurol-S (CAS) agar medium. Indole-3-acetic acid (IAA) and gibberellins (GAs), namely GA 1 , GA 3 , GA 4 , GA 7 , GA 9 , GA 12 , GA 15 , and GA24, were quantified by GC/MS-SIM analysis. The expression levels of genes involved in GA and IAA biosynthesis, such as cyp112, cyp114 , trpA, and trpB , were assessed using semi-quantitative RT-PCR. Plant bioassays showed that As at a 15 mg/kg concentration reduced plant growth, chlorophyll content, and biomass. However, IU31 inoculation significantly improved plant growth dynamics, enhancing As accumulation by up to 50% compared with uninoculated plants. IU31 inoculation induced the bioconcentration factor (BCF) and bioaccumulation factor (BAF) of As in plants compared to uninoculated plants, but the translocation factor (TF) of As was unaffected by IU31 inoculation. IU31 inoculation effectively restored glutathione-S-transferase (GST) and catalase (CAT) enzyme activities, as well as glutathione (GSH) and hydrogen peroxide concentrations to nearly normal levels, which were significantly elevated in plants exposed to As stress. These results show that IU31 improves plant health and growth by producing IAA and GAs, which might contribute to the uptake and detoxification of As. [Display omitted] • Plant growth-promoting Bacillus subtilis strain IU31 was isolated from the rhizosphere. • The IU31 produced phytohormones and siderophores and solubilized phosphate. • Gibberellins and IAA of bacteria were quantified by GC-MS. • Semiquantitative RT-PCR was used to measure the expression of trpA, trpB, cyp112 , and cyp114 genes. • Infection of rice plants with IU31 results in increased growth and biomass. [ABSTRACT FROM AUTHOR]

Diffusive gradients in thin films technique (DGT) is recognized as a more reliable method for determining labile heavy metal (HM) concentration in soil than traditional destructive methods. However, the current DGT measurement index, C DGT , theoretically underestimates the true labile concentration (C labile) of HMs in soil and lacks direct comparability with the conventional soil HM content indices due to unit differences. Here, we proposed C DGT-W , a new simple index which is defined as the HM accumulation in the binding layer, normalized to the weight of soil (optimized water content = 100% of the maximum water holding capacity) filled in the open cavity-type DGT device over a specified deployment time (optimized time = 24 h). The procedure for measuring C DGT-W is analogous to that of C DGT but includes precise determination of water content (water/dry soil) and the mass of soil filled in the cavity. We conducted measurements of Cu, Pb, Cr(Ⅵ) and As(V) as C DGT-W , C DGT , solution concentration (C soln), and CaCl 2 extractable concentration (C CaCl2) on three soils with a diverse range of HM concentrations. C DGT-W showed significant linear correlations with all other tested indexes. The ratios of C DGT-W to C CaCl2 varied between 0.30 and 0.98 for all HM–soil combinations with only one exception, a range much greater than C DGT /C soln (typically <0.1) but lower than 1. This suggested that C DGT-W may more accurately reflect C labile than C DGT (theoretically underestimates C liable) and C CaCl2 (likely overestimates C liable). Additionally, C DGT-W measurements for these four HMs exhibited a broad measure concentration range and a low detection limit (mg/kg level). Consequently, C DGT-W may offer a more reliable alternative to C DGT for characterizing C labile in unsaturated soils. [Display omitted] • We proposed a new index C DGT-W to measure labile content of heavy metals in soil (C labile). • C DGT-W linearly correlated to CaCl 2 extractable content (C CaCl2) and C DGT. • C DGT-W may more accurately reflect C labile than C DGT and C CaCl2. • C DGT-W is probably a better measure of C labile than C DGT in unsaturated soil. [ABSTRACT FROM AUTHOR]

Arsenic (As) is a notorious environmental toxicant widely present in various natural environments. As exposure has been correlated with the decline in sperm motility. Yet, the mechanism has not been fully elucidated. Adult male C57 mice were given 0, 1, or 15 mg/L NaAsO 2 for 10 weeks. The mature seminiferous tubules and sperm count were decreased in As-exposed mice. Sperm motility and several sperm motility parameters, including average path velocity (VAP), straight-line velocity (VSL), curvilinear velocity (VCL), beat-cross frequency (BCF), linearity (LIN), straightness (STR), and amplitude of lateral head displacement (ALH), were declined in As-exposed mice. RNA sequencing and transcriptomics analyses revealed that differentially expressed genes (DEGs) were mainly enriched in metabolic pathways. Untargeted metabolomics analyses indicated that energy metabolism was disrupted in As-exposed mouse testes. Gene set enrichment analysis showed that glycolysis and oxidative phosphorylation were disturbed in As-exposed mouse testes. As-induced disruption of testicular glucose metabolism and oxidative phosphorylation was further validated by RT-PCR and Western blotting. In conclusion, As exposure causes decline in sperm motility accompanied by energy metabolism disorders in mouse testes. [Display omitted] • As (arsenic) exposure reduced sperm motility and several sperm motility parameters. • Transcriptomics and metabolomics showed that As disturbs energy metabolism. • Gene set enrichment analysis revealed that As inhibits oxidative phosphorylation. • As-induced energy metabolism disorders were verified by RT-PCR and Western blotting. [ABSTRACT FROM AUTHOR]

Simultaneously stabilizing of arsenic (As) and cadmium (Cd) in co-contaminated soil presents substantial challenges due to their contrasting chemical properties. Schwertmannite (Sch) is recognized as a potent adsorbent for As pollution, with alkali modification showing promising results in the simultaneous immobilization of both As and Cd. This study systematically investigated the long-term stabilization efficacy of alkali-modified Sch in Cd–As co-contaminated farmland soil over a 200-day flooding-drying period. The results revealed that As showed significant mobility in flooded conditions, whereas Cd exhibited increased soil availability under drying phases. The addition of Sch did not affect the trends in soil pH and Eh fluctuations; nonetheless, it led to an augmentation in the levels of amorphous iron oxides and SO 4 2− concentration in soil pore water. At a dosage of 0.5% Sch, there was a notable decrease in the mobility and soil availability of As and Cd under both flooding (34.5% and 53.6% at Day 50) and drying conditions (27.0% and 29.4% at Day 130), primarily promoting the transformation of labile metal(loid) fraction into amorphous iron oxide-bound forms. Throughout the flooding-drying treatment period, Sch maintained stable mineral morphology and mineralogical phase, highlighting its long-term stabilization effect. The findings of this study emphasize the promising application of Sch-based soil remediation agents in mitigating the challenges arising from As–Cd co-contamination. Further research is warranted to explore their application in real farmland settings and their impact on the uptake of toxic metal(loid)s by plants. [Display omitted] • Schwertmannite (Sch) exhibited efficient co-stabilization capabilities for As and Cd. • Sch did not cause significant changes in soil pH/Eh during 200-day flooding-drying period. • Sch reduced soil availability and mobility of As and Cd in both flooding and drying conditions. • Sch exhibited remarkable stability in mineral morphology and mineralogical phase. [ABSTRACT FROM AUTHOR]

Arsenic (As) is a heavy metal known for its detrimental effects on the kidneys, but the precise mechanisms underlying its toxicity remain unclear. In this study, we employed an integrated approach combining traditional toxicology methods with functional metabolomics to explore the nephrotoxicity induced by As in mice. Our findings demonstrated that after 28 days of exposure to sodium arsenite, blood urea nitrogen, serum creatinine levels were significantly increased, and pathological examination of the kidneys revealed dilation of renal tubules and glomerular injury. Additionally, uric acid, total cholesterol, and low-density lipoprotein cholesterol levels were significant increased while triglyceride level was decreased, resulting in renal insufficiency and lipid disorders. Subsequently, the kidney metabolomics analysis revealed that As exposure disrupted 24 differential metabolites, including 14 up-regulated and 10 down-regulated differential metabolites. Ten metabolic pathways including linoleic acid and glycerophospholipid metabolism were significantly enriched. Then, 80 metabolic targets and 168 predicted targets were identified using metabolite network pharmacology analysis. Of particular importance, potential toxicity targets, such as glycine amidinotransferase, mitochondrial (GATM), and nitric oxide synthase, and endothelial (NOS3), were prioritized through the "metabolite-target-pathway" network. Receiver operating characteristics curve and molecular docking analyses suggested that 1-palmitoyl-2-myristoyl-sn-glycero-3-PC, linoleic acid, and L-hydroxyarginine might be functional metabolites associated with GATM and NOS3. Moreover, targeted verification result showed that the level of linoleic acid in As group was 0.4951 μg/mL, which was significantly decreased compared with the control group. And in vivo and in vitro protein expression experiments confirmed that As exposure inhibited the expression of GATM and NOS3. In conclusion, these results suggest that As-induced renal injury may be associated with the inhibition of linoleic acid metabolism through the down-regulation of GATM and NOS3, resulting in decreased levels of linoleic acid, 1-palmitoyl-2-myristoyl-sn-glycero-3-PC, and L-hydroxyarginine metabolites. [Display omitted] • Linoleic acid metabolism was inhibited by Arsenic in renal injury mice. • Linoleic acid and L-hydroxyarginine were the potential functional metabolites. • The GATM and NOS3 may be the toxic targets in As-induced nephrotoxicity. [ABSTRACT FROM AUTHOR]

Water management in paddy soils can effectively reduce the soil-to-rice grain transfer of either As or Cd, but not of both elements simultaneously due to the higher mobility of As under reducing and Cd under oxidizing soil conditions. Limestone amendment, the common form of liming, is well known for decreasing Cd accumulation in rice grown on acidic soils. Sulfate amendment was suggested to effectively decrease As accumulation in rice, especially under intermittent soil flooding. To study the unknown effects of combined sulfate and limestone amendment under intermittent flooding for simultaneously decreasing As and Cd in rice, we performed a pot experiment using an acidic sandy loam paddy soil. We also included a clay loam paddy soil to study the role of soil texture in low-As rice production under intermittent flooding. We found that liming not only decreased rice Cd concentrations but also greatly decreased dimethylarsenate (DMA) accumulation in rice. We hypothesize that this is due to suppressed sulfate reduction, As methylation, and As thiolation by liming in the sulfate-amended soil and a higher share of deprotonated DMA at higher pH which is taken up less readily than protonated DMA. Decreased gene abundance of potential soil sulfate-reducers by liming further supported our hypothesis. Combined sulfate and limestone amendment to the acidic sandy loam soil produced rice with 43% lower inorganic As, 72% lower DMA, and 68% lower Cd compared to the control soil without amendment. A tradeoff between soil aeration and water availability was observed for the clay loam soil, suggesting difficulties to decrease As in rice while avoiding plant water stress under intermittent flooding in fine-textured soils. Our results suggest that combining sulfate amendment, liming, and intermittent flooding can help to secure rice safety when the presence of both As and Cd in coarse-textured soils is of concern. [Display omitted] • Combined soil sulfate and limestone amendment decreased iAs, DMA, and Cd in rice. • Liming decreased DMA in rice by >70% by decreasing protonated DMA in porewater. • It is trickier to control rice As in a more clayey soil under intermittent flooding. [ABSTRACT FROM AUTHOR]

Arsenic is a well-known human carcinogen whose environmental exposure via drinking water, food, and air impacts millions of people across the globe. Various mechanisms of arsenic carcinogenesis have been identified, ranging from damage caused by excessive production of free radicals and epigenetic alterations to the generation of cancer stem cells. A growing body of evidence supports the critical involvement of the endoplasmic stress-activated unfolded protein response (UPR) in promoting as well as suppressing cancer development/progression. Various in vitro and in vivo models have also demonstrated that arsenic induces the UPR via activation of the PERK, IRE1α, and ATF6 proteins. In this review, we discuss the mechanisms of arsenic-induced endoplasmic reticulum stress and the role of each UPR pathway in the various cancer types with a focus on the epigenetic regulation and function of the ATF6 protein. The importance of UPR in arsenic carcinogenesis and cancer stem cells is a relatively new area of research that requires additional investigations via various omics-based and computational tools. These approaches will provide interesting insights into the mechanisms of arsenic-induced cancers for prospective target identification and development of novel anti-cancer therapies. [Display omitted] • Arsenic activates ER stress-UPR linked to metabolic shift. • Differential epigenetic landscapes are found on ATF6 and ATF6B genes. • Nrf2 affects super-enhances on ATF6 and ATF6B genes. • ER stress-UPR contributes to arsenic carcinogenesis. [ABSTRACT FROM AUTHOR]

This study addresses the pressing issue of high arsenic (As) contaminations, which poses a severe threat to various life forms in our ecosystem. Despite this prevailing concern, all organisms have developed some techniques to mitigate the toxic effects of As. Certain plants, such as bryophytes, the earliest land plants, exhibit remarkable tolerance to wide range of harsh environmental conditions, due to their inherent competence. In this study, bryophytes collected from West Bengal, India, across varying contamination levels were investigated for their As tolerance capabilities. Assessment of As accumulation potential and antioxidant defense efficiency, including SOD, CAT, APX, GPX etc. revealed Marchantia polymorpha as the most tolerant species. It exhibited highest As accumulation, antioxidative proficiency, and minimal damage. Transcriptomic analysis of M. polymorpha exposed to 40 μM As(III) for 24 and 48 h identified several early responsive differentially expressing genes (DEGs) associated with As tolerance. These includes GSTs, GRXs, Hsp20s, SULTR1;2, ABCC2 etc., indicating a mechanism involving vacuolar sequestration. Interestingly, one As(III) efflux-transporter ACR3 , an extrusion pump, known to combat As toxicity was found to be differentially expressed compared to control. The SEM-EDX analysis, further elucidated the operation of As extrusion mechanism, which contributes added As resilience in M. polymorpha. Yeast complementation assay using Δ acr3 yeast cells, showed increased tolerance towards As(III), compared to the mutant cells, indicating As tolerant phenotype. Overall, these findings significantly enhance our understanding of As tolerance mechanisms in bryophytes. This can pave the way for the development of genetically engineered plants with heightened As tolerance and the creation of improved plant varieties. [Display omitted] • Marchantia polymorpha shows high arsenic (As) accumulation and tolerance. • Tolerance mechanism mediated by better antioxidant defense systems. • Expression of GST , Hsp20 , ABCC2 indicates accumulation via vacuolar sequestration. • Arsenite extrusion pump, ACR3, plays indirect role in governing As tolerance. [ABSTRACT FROM AUTHOR]

Arsenic (As) pollution in agricultural systems poses a serious threat to crop productivity and food safety. Silicon (Si) has been reported to mitigate toxic effects of heavy metals in plants. However, the mechanisms behind Si-mediated alleviation of As toxicity in rice (Oryza sativa L.) remain poorly understood. Here, we performed metagenomic and biochemical analyses to investigate the potential of Si in alleviating As toxicity to rice plants. As exposure reduced plant growth, chlorophyll contents, antioxidant enzyme levels and soil enzymes activity, while increasing reactive oxygen species (ROS) activity and inducing alterations in the rhizosphere microbiome of rice seedlings. Silicon amendments enhanced rice growth (24%), chlorophyll a (25%), and chlorophyll b (26.7%), indicating enhanced photosynthetic capacity. Si amendments also led to the upregulation of antioxidant enzymes viz., superoxide dismutase (15.4%), and peroxidase (15.6%), resulting in reduced ROS activity and oxidative stress compared to the As-treated control. Furthermore, Si treatment reduced uptake and translocation of As in rice plants, as evidenced by the analysis of elemental contents. Microscopic examination of leaf and root ultrastructure showed that Si mitigated As-induced cellular damage and maintained normal morphology. Metagenomic analysis of the rice rhizosphere microbiome revealed that Si application modulated composition and diversity of microbial communities e.g., Proteobacteria, Actinobacteria, and Firmicutes. Additionally, Si amendments upregulated the relative expression levels of OsGSH, OsPCs, OsNIP1;1 and OsNIP3;3 genes, while the expression levels of the OsLis1 and OsLis2 genes were significantly downregulated compared with As-treated rice plants. Overall, these findings contribute to our understanding of Si-mediated plant resilience to As stress and offer potential strategies for sustainable agriculture in As-contaminated regions. [Display omitted] • Silicon (Si) application mitigates arsenic (As) toxicity, promoting rice growth and chlorophyll production. • Si enhanced antioxidant enzymes and reduced reactive oxygen species activity, mitigating As-induced oxidative stress in rice. • Si positively influences the nutrient status and soil enzymes activity. • Metagenome sequencing unveils the impact of Si on the rice rhizosphere microbiome. • Si amendments modulate the gene expression related to glutathione, phytochelatins, and membrane transporters, conferring improved As tolerance. [ABSTRACT FROM AUTHOR]

In this study, a soil incubation experiment was conducted to explore the influence MgO-treated corn straw biochar (MCB) on the bioavailability and chemical forms of cadmium (Cd), lead (Pb), and arsenic (As), alongside the impact on the bacterial community within paddy soil subjected to both flooded and non-flooded conditions. Raw corn straw biochar (CB) served as the unmodified biochar control, aiding in the understanding of the biochar's role within the composite. The results showed that even at a minimal concentration of 0.5 %, MCB exhibited higher effectiveness in reducing the bioavailability of Pb and Cd compared to 1 % CB. In non-flooded conditions, 0.5 % MCB reduced the bioavailable Pb and Cd by 99.7 % and 87.4 %, respectively, while NaH 2 PO 4 -extracted As displayed a 14.5 % increase. With increasing MCB concentrations (from 0.5 % to 1.5 %), soil pH, DOC, EC, available phosphorus, and bioavailable As increased, while bioavailable Pb and Cd exhibited declining tendencies. Flooding did not notably alter MCB's role in reducing Pb and Cd bioavailability, yet it systematically amplified As release. Heavy metal fractions extracted by acetic acid increased in the MCB groups under flooding conditions, especially for As. The inclusion of 0.5 % MCB did not noticeably affect bacterial diversity, whereas higher doses led to reduced diversity and substantial changes in community composition. Specifically, the groups with MCB showed an increase in the Bacteroidetes and Proteobacteria phyla, accompanied by a decrease in Acidobacteria. These alterations were primarily attributed to the increased pH and EC resulting from MgO hydrolysis. Consequently, for Pb/Cd stabilization and soil bacterial diversity, a low dosage of MgO-treated biochar is recommended. However, caution is advised when employing MgO-treated biochar in soils with elevated arsenic levels, particularly under flooded conditions. [Display omitted] • MCB significantly reduced Pb/Cd bioavailability under different water conditions. • Waterlogging treatment and MCB synergistically promoted As release. • MCB increased soil pH, DOC and available P, affecting HMs transformation. • HOAc-extracted fractions in groups with MCB addition was enhanced by flooding. • Soil bacterial diversity decreased with increasing MCB due to high EC. [ABSTRACT FROM AUTHOR]

As one of the first identified oncogenic microRNAs, the precise details concerning the transcriptional regulation and function of microRNA-21 (miR-21) are still not completely established. The miR-21 gene is situated on chromosome 17q23.2, positioned at the 3′-UTR of the gene that encodes vacuole membrane protein-1 (VMP1). In this current study, we presented evidence indicating that miR-21 possesses its own gene promoter, which can be found in the intron 10 of the VMP1 gene. Chromatin immunoprecipitation followed by global DNA sequencing (ChIP-seq) revealed the presence of a broad H3K4me3 peak spanning the entire gene body of the primary miR-21 and the existence of super-enhancer clusters in the close proximity to both the miR-21 gene promoter and the transcription termination site in arsenic (As3+)-induced cancer stem-like cells (CSCs) and human induced pluripotent stem cells (hiPSCs). In non-transformed human bronchial epithelial cells (BEAS-2B), As3+ treatment enhanced Nrf2 binding to both the host gene VMP1 of miR-21 and the miR-21 gene. Knockout of Nrf2 inhibited both the basal and As3+-induced expressions of miR-21. Furthermore, the As3+-enhanced Nrf2 peaks in ChIP-seq fully overlap with these super-enhancers enriched with H3K4me1 and H3K27ac in the miR-21 gene, suggesting that Nrf2 may coordinate with other transcription factors through the super-enhancers to regulate the expression of miR-21 in cellular response to As3+. These findings demonstrate the unique genetic and epigenetic characteristics of miR-21 and may provide insights into understanding the novel mechanisms linking environmental As3+ exposure and human cancers. [Display omitted] • Pri-miR-21 gene overlaps with VMP1 gene from intron 10 to 3′-UTR. • Pri-miR-21 possesses its own gene promoter regulatable by arsenic. • Super-enhancers were identified on pri-miR-21 gene. • Arsenic-induced miR-21 is Nrf2 as well as ATF3 dependent. • Higher level of miR-21 is associated with poorer survival of the cancer patients. [ABSTRACT FROM AUTHOR]

Anthropogenic pollution is identified as an important threat to bird and other wildlife populations. Many metals and toxic elements, along with poly- and perfluoroalkyl substances (PFASs) are known to induce immunomodulation and have previously been linked to increased pathogen prevalence and infectious disease severity. In this study, the house sparrow (Passer domesticus) was investigated at the coast of Helgeland in northern Norway. This population is commonly infected with the parasitic nematode "gapeworm" (Syngamus trachea), with a prevalence of 40–60 % during summer months. Gapeworm induces severe respiratory disease in birds and has been previously demonstrated to decrease survival and reproductive success in wild house sparrows. The aim of this study was to investigate whether a higher exposure to pollution with PFASs, metals and other elements influences gapeworm infection in wild house sparrows. We conducted PFASs and elemental analysis on whole blood from 52 house sparrows from Helgeland, including analyses of highly toxic metals such as lead (Pb), mercury (Hg) and arsenic (As). In addition, we studied gapeworm infection load by counting the parasite eggs in faeces from each individual. We also studied the expression of microRNA 155 (miR155) as a key regulator in the immune system. Elevated blood concentrations of Pb were found to be associated with an increased prevalence of gapeworm infection in the house sparrow. The expression of miR155 in the plasma of the house sparrow was only weakly associated with Pb. In contrast, we found relatively low PFASs concentrations in the house sparrow blood (∑ PFASs 0.00048–354 μg/L) and PFASs were not associated to miR155 nor infection rate. The current study highlights the potential threat posed by Pb as an immunotoxic pollutant in small songbirds. [Display omitted] • Helgeland, northern Norway, local bird populations are contaminated by toxic elements. • Elevated Pb levels modulate the expression of miR155. • Elevated blood concentrations of Pb are linked to a higher prevalence of gapeworm infection. [ABSTRACT FROM AUTHOR]

In contaminated soil sites, the coexistence of inorganic and organic contaminants poses a significant threat to both the surrounding ecosystem and public health. However, the migration characteristics of these co-contaminants within the soil and their interactions with key components, including Fe-bearing minerals, organic matter, and microorganisms, remain unclear. This study involved the collection of a 4.3-m-depth co-contaminated soil profile to investigate the vertical distribution patterns of co-contaminants (namely, arsenic, cadmium, and polychlorinated biphenyls (PCBs)) and their binding mechanisms with environmental factors. The results indicated a notable downward accumulation of inorganic contaminants with increasing soil depth, whereas PCBs were predominantly concentrated in the uppermost layer. Chemical extraction and synchrotron radiation analysis highlighted a positive correlation between the abundance of reactive iron (Fe CBD) and both co-contaminants and microbial communities in the contaminated site. Furthermore, Mantel tests and structural equation modeling (SEM) demonstrated the direct impacts of Fe CBD and microbial communities on co-contaminants within the soil profile. Overall, these results provided valuable insights into the migration and transformation characteristics of co-contaminants and their binding mechanisms mediated by minerals, organic matter, and microorganisms. [Display omitted] • Contaminated elements (As and Cd) migrate downward into the soil, unlike PCBs. • The reactive iron in the upper soil binds to co-contaminants stronger. • Microscale analysis showed heterogeneity in Fe-bearing minerals and contaminants. • Reactive iron and bacterial communities directly affect co-contaminant behaviors. [ABSTRACT FROM AUTHOR]

This study aimed to gauge the toxicity of potentially toxic elements (PTEs) in coconut crops cultivated in arsenic-contaminated areas while offering a global perspective encompassing more than 100 impacted countries. The current investigation provides crucial insights into the assessment of PTEs pollution using the Bioaccumulation factor, Geo-accumulation index, Potential ecological risk index, Hazardous index, and Lifetime cancer risk (LCR) and highlights the potential human health risks posed by contaminated food, water, and soil. From 22 severely polluted sites in West Bengal, India, soil, groundwater (GW), and coconut water (CW) samples were collected, acidified, and digested using microwave digestion, for PTEs quantification using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Results revealed that despite high concentrations of arsenic in soils (4.6 ± 3.4 mg kg−1), and GW (22.2 ± 150.9 μg L−1), CW (0.7 ± 3.1 μg L−1) levels were within permissible limits. Groups of PTEs with comparable sources and distributions were discovered through Principal Component Analysis (PCA). A speciation diagram was used to predict the prevalence of arsenic species in all three matrices. The Hazardous Index (HI < 1) indicated no probability of non-carcinogenic diseases for children and adults in all the compartments. However, exposure to GW and soil contaminated with Cr, As, and Cd by children (9.02 × 10−13 to 2.77 × 10−4) and adults (6.51 × 10−14 to 1.18 × 10−4) would increase their susceptibility to cancer (LCR >10−6). The study concluded that moderate lifetime consumption of CW is safe and has no significant impact on healthy individuals. Additionally, CW is a rich source of essential micronutrients such as Zn, Fe, Mn, and B. Overall, the findings of this study could help in developing appropriate strategies for reducing PTEs contamination and protecting human health. [Display omitted] • Coconut grown in As and other PTEs enriched soil is safe and poses no cancer risk. • The Eh-pH diagram showed As(III & V) in CW and As(V) in soil & groundwater. • A PCA study indicates anthropogenic Pb and Zn contamination. • Ecotoxicological Indices show environmental threats from high levels of As and Cd. • The noxious presence of Cd, As, and Cr in soil and groundwater can cause cancer. [ABSTRACT FROM AUTHOR]

In this study, ceria nanoparticle (CNP) was used as a capping agent to investigate the efficiency and mechanism of simultaneously controlling the release of sediment internal Arsenic (As) and tungsten (W). The results of incubation experiment demonstrated that CNP capping reduced soluble As and W by 81.80% and 97.97% in overlying water, respectively; soluble As and W by 65.64% and 60.13% in pore water, respectively; and labile As and W in sediment by 45.20% and 53.20%, respectively. The main mechanism of CNP controlling sediment internal As and W was through adsorption via ligand exchange and inner-sphere complexation, as determined through adsorption experiments, XPS and FIRT spectra analysis. Besides, CNP also acted as an oxidant, facilitating the oxidation of AsⅢ to AsV and thereby enhancing the adsorption of soluble As. Additionally, sediment As and W fractions experiments demonstrated that the immobilization of As and W with CNP treatment via transforming mobile to stable fractions was another mechanism inhibiting sediment As and W release. The obtained significant positive correlation between soluble As/W and Fe/Mn, labile As/W and Fe/Mn indicated that iron (Fe) and manganese (Mn) oxidation, influenced by CNP, serve as additional mechanisms. Moreover, Fe redox plays a crucial role in controlling internal As and W, while Mn redox plays a more significant role in controlling As compared to W. Meanwhile, CNP capping effectively prevented the release of As and W by reducing the activity of microorganisms that degrade Fe-bound As and W and reduced the release risk of V, Cr, Co, Ni, and Zn from sediments. Overall, this study proved that CNP was a suitable capping agent for simultaneously controlling the release of As and W from sediment. [Display omitted] • CNP capping can simultaneously inhibit the release of sediment internal As and W. • CNP capping reduced sediment internal As and W release potential. • CNP capping promoted the oxidation of iron (Fe) and manganese (Mn). • The redox of Fe and Mn played a key role in controlling sediment internal As and W release. • CNP capping did not increase the release risk of V, Cr, Co, Ni, and Zn from sediments. [ABSTRACT FROM AUTHOR]

Sulfate concentrations in eutrophic waters continue to increase; however, the transformations of arsenic (As) in sediments under these conditions are unclear. In this study, we constructed a series of microcosms to investigate the effect of algal degradation on As transformations in sediments with high sulfate concentrations. The results showed that both the elevated sulfate levels and algal degradation enhanced the release of As from sediments to the overlying water, and degradation of algal in the presence of elevated sulfate levels could further contribute to As release. Sulfate competed with arsenate for adsorption in the sediments, leading to As desorption, while algal degradation created a strongly anaerobic environment, leading to the loss of the redox layer in the surface sediments. With high sulfate, algal degradation enhanced sulfate reduction, and sulfur caused the formation of thioarsenates, which may cause re-dissolution of the arsenides, enhancing As mobility by changing the As speciation. The results of sedimentary As speciation analysis indicated that elevated sulfur levels and algal degradation led to a shift of As from Fe 2 O 3 /oxyhydroxide-bound state to specifically adsorbed state at the sediment water interface. This study indicated that algal degradation increases the risk of As pollution in sulfate-enriched eutrophic waters. [Display omitted] • Elevated sulfate in water promoted sedimentary As release under oxic condition. • Sulfate reduction and iron(Fe) speciation transformation together control As release. • Elevated sulfate and algal degradation reduced Fe 2 O 3 /oxyhydroxides-bound As. • Algal degradation under high sulfate enhanced the As release from sediments. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) is a form of environmental pollution from mining activity that can negatively affect soil environments by acidification, salinisation, and metal(loid) contamination. The use of plants to remediate (phytoremediation) these impacted environments while generating plant-based value is a promising approach to more accessible and cost-benefiting restoration of post-mining, marginal lands. In this study, a 3-month growth-chamber pot experiment was conducted to investigate the influence of co-cropping two plant species, Chrysopogon zizanioides (vetiver grass) and the legume Medicago truncatula (barrel clover) with a wheat straw biochar amendment on the phytostabilisation of metal(loid)s Cr, Zn, and As and the phytoextraction of rare earth element (REE) in an AMD impacted soil from a gold mining region in South Africa. The results showed that co-cropping with vetiver significantly lowered the legume's Cr, Zn, and As root contents by 80%, 32% and 54%, respectively, and improved the plant's overall metal(loid) tolerance by increasing its translocation from root to shoot tissue. The biochar further inhibited root uptake of Cr and Zn, by 71% and 36%, and increased the legume biomass by 40%. Both plant species and cropping treatments exhibited low REE extraction capabilities by shoot tissue, which accounted for less than 0.2% of total soil REE contents. The study shows that co-cropping with vetiver and biochar amendment are effective tools for the phytoremediation of AMD impacted soil mainly by lowering plant uptake and improving plant metal(loid) tolerance. Likely mechanisms at play include the alteration of rhizosphere chemistry and species-specific physiological and molecular responses. These effects offer support for the phytostabilisation of AMD impacted soil with the generation of plant-based value through dual (and safe) cultivation (phytoprotection) rather than through REE recovery from plant biomass (phytoextraction). These techniques could allow for the simultaneous restoration of post-mining, mining-impacted and marginal lands with agricultural production. [Display omitted] • Co-cropping was investigated as a phytoremediation tool for acid mine drainage impacted soil. • A vetiver grass and legume co-cropping system improved plant metal tolerance. • Vetiver grass could be used for phytoprotection and phytostabilisation in mining polluted soil. • Co-cropping was not an effective strategy for phytoextraction of rare earth elements. [ABSTRACT FROM AUTHOR]

In this study, smelter contaminated soil was treated with various soil amendments (ferric sulfate [Fe 2 (SO4) 3 ], triple superphosphate [TSP] and biochar) to determine their efficacy in immobilizing soil lead (Pb) and arsenic (As). In soils incubated with ferric sulfate (0.6M), gastric phase Pb bioaccessibility was reduced from 1939 ± 17 mg kg−1 to 245 ± 4.7 mg kg−1, while intestinal phase bioaccessibility was reduced from 194 ± 25 mg kg−1 to 11.9 ± 3.5 mg kg−1, driven by the formation of plumbojarosite. In TSP treated soils, there were minor reductions in gastric phase Pb bioaccessibility (to 1631 ± 14 mg kg−1) at the highest TSP concentration (6000 mg kg−1) although greater reductions were observed in the intestinal phase, with bioaccessibility reduced to 9.3 ± 2.2 mg kg−1. Speciation analysis showed that this was primarily driven by the formation of chloropyromorphite in the intestinal phase following Pb and phosphate solubilization in the low pH gastric fluid. At the highest concentration (10% w/w), biochar treated soils showed negligible decreases in Pb bioaccessibility in both gastric and intestinal phases. Validation of bioaccessibility outcomes using an in vivo mouse assay led to similar results, with treatment effect ratios (TER) of 0.20 ± 0.01, 0.76 ± 0.11 and 1.03 ± 0.10 for ferric sulfate (0.6M), TSP (6000 mg kg−1) and biochar (10% w/w) treatments. Results of in vitro and in vivo assays showed that only ferric sulfate treatments were able to significantly reduce As bioaccessibility and bioavailability with TER at the highest application of 0.06 ± 0.00 and 0.14 ± 0.04 respectively. This study highlights the potential application of ferric sulfate treatment for the immobilization of Pb and As in co-contaminated soils. [Display omitted] • The efficacy of three Pb remediation treatments was assessed. • Ferric sulfate amendments effectively reduced both Pb and As bioaccessibility. • Pb bioaccumulation in mice was reduced by up to 80%. • Up to 83% of Pb in ferric sulfate-treated soils was converted to plumbojarosite. • Other amendments were ineffective at reducing Pb or As bioavailability. [ABSTRACT FROM AUTHOR]

Large amount of coal ash is produced as industrial waste during the electricity generation through the combustion of lignite. Toxic elements arsenic exists in the coal ash, which hinders the subsequent recycling processes. Moreover, coal ash could be recycled further to retrieve scattered metals germanium and tungsten. It is believed that traditional recycling methods present barriers to scaled application, especially serious secondary pollution, such as toxic residue and waste liquid. In this work, a novel sequential vacuum distillation with disulphide method is proposed to separate arsenic, germanium and tungsten from coal ash. First, arsenic can be volatilized completely out of the reaction system at temperatures below 550 °C. Subsequently, Ge and W volatilized in the form of sulfide in the presence of Na 2 S 2 O 3. The optimal condition was 1050 °C, the mass ratio of 0.6 with reaction a pressure of 1 Pa and a time duration of 120 min demonstrated the best evaporation ratio. For coal fly ash, chemical species As 2 S 3 , GeS, and WO x (x < 3)/WS 2 were the main condensed products. For coal bottom ash, As 2 S 3 , GeS, and WO 3 /WS 2 were dominant chemical components. Mechanisms for the process of release and evaporation of As, Ge, and W from coal ash, vacuum reaction, evaporation, and condensation were analyzed. In summary, the vacuum distillation method deserves to be further developed as it provides an eco-friendly method to recycle coal ash. [Display omitted] • An environment-friendly sequential vacuum distillation method is proposed. • Mixed sulfide reagents are used to remove As and recycle Ge, and W step by step. • As 2 S 3 , GeS, and WO x (x < 3)/WS 2 are the main condensed products in ash. • Mechanisms of release and evaporation processes of As, Ge, and W are analyzed. • Residues are not a hazardous material and can be further recycled. [ABSTRACT FROM AUTHOR]

Arsenic (As) pollution in wetlands has emerged as a serious global concern, posing potential threat to the growth of wetland plants. Arbuscular mycorrhizal fungi (AMF) can alleviate As phytotoxicity to host plants, but their ecological functions in wetland plants under flooding conditions remain largely unknown. Thus, a pot experiment was conducted using Rhizophagus irregularis and Iris tectorum Maxim. exposed to light (15 and 30 mg/kg As) and high (75 and 100 mg/kg As) levels of As, to investigate the intrinsic mechanisms underlying the effects of mycorrhizal inoculation on plant As tolerance under flooding conditions. The mycorrhizal colonization rates ranged from 31.47 ± 3.92 % to 60.69 ± 5.58 %, which were higher than the colonization rate (29.55 ± 13.60%) before flooding. AMF significantly increased biomass of I. tectorum under light As levels, together with increased phosphorus (P) and As uptake. Moreover, expression of arsenate reductase gene RiarsC and a trace of dimethylarsenic (1.87 mg/kg in shoots) were detected in mycorrhizal plants, suggesting As transformation and detoxification by AMF exposed to light levels of As. However, under high As levels, AMF inhibited As translocation from roots to shoots, and facilitated the formation of iron plaque. The immobilized As concentrations in iron plaque of mycorrhizal plants were respectively 1133.68 ± 179.17 mg/kg and 869.11 ± 248.90 mg/kg at 75 and 100 mg/kg As addition level, both significantly higher than that in non-inoculated plants. Irrespective of As exposure levels, mycorrhizal symbiosis decreased soil As bioavailability. Overall, the study provides insights into the alleviation of As phytotoxicity in natural wetland plants through mycorrhizal symbiosis, and potentially indicates function diversity of AMF under flooding conditions and As stress, supporting the subsequent phytoremediation and restoration of As-contaminated wetlands. [Display omitted] • Arbuscular mycorrhizal fungi (AMF) survived in flooding conditions. • AMF improved plant growth and upregulated RiarsC under light As levels. • Mycorrhizal symbiosis facilitated iron plaque formation under high As levels. • Mycorrhizal inoculation decreased soil As bioavailability. [ABSTRACT FROM AUTHOR]

Physical, chemical weathering and volcanic eruptions release heavy metals into soils and surface waters naturally. Contaminants from anthropogenic sources originated from industrial and municipality waste substantially modify and increase their contributions. They are then absorbed by fish gills, amphipod cuticles, and other sensitive organs of aquatic creatures. This article discusses the essences on the determination, potential and plausible factors of trophic transfer and biomagnification of environmental contaminants particularly heavy metals across aquatic ecosystem. In general, arsenic is found to be bio-diminished across food webs in freshwater ecosystem while it biomagnified in marine ecosystem of higher trophic level (tertiary consumer of predatory fish) and dilute its concentration from lower trophic level (from producer to bottom level of consumer, secondary and lastly to tertiary consumer (forage fish)). Early study for Cadmium shown that it has no potential for biomagnification while later studies prove that cadmium does magnify for gastropod and epiphyte-based food webs. Mercury shown obvious biomagnification potential where it can bio-magnify from trophic level as low as particulate organic matter (POM) to higher trophic of fish. These findings proved that aquatic ecosystems must be preserved from contamination not just for human benefit, but also to prevent environmental degradation and biodiversity loss. [Display omitted] • Determination of trophic transfer and biomagnification potential involve a series of quantification analysis. • Internal and external factors further affect the trophodynamics of heavy metal in aquatic ecosystem. • Trophic transfer varies depending on the length of food chain. • Biomagnification or biodilution is based on the tissue and metabolism of an organism. • Presence of some detected metals are not harmful for human consumption. [ABSTRACT FROM AUTHOR]

Long-term exposure to geogenic arsenic (As)-contaminated groundwater poses a severe threat to public health problems. Generally, elevated As concentrations have been observed with high amounts of ammonium in groundwater of floodplains. An extreme gradient boosting algorithm was conducted to develop a probability model based on hydrogeochemical data, which predicted the occurrence rates of groundwater As on a regional scale. Results showed that concentrations of NH 4 +, Eh, K, Cl−, SO 4 2−, and NO 3 − were powerful predictive variables of As exposure. The model revealed the co-enrichment of As with NH 4 +, suggesting that the mineralization of nitrogen-containing organic matter promoted the reduction of As-bearing iron-oxides. The predicted distribution of high-As groundwater showed high consistency with known spatial distribution of As contamination, and the model also accurately predicted As concentrations in Jiangbei Plain of China and typical As-affected floodplains of Southeast Asia. The model can serve as a low-cost and rapid virtual sensor for detecting As concentrations in private or newly drilled wells, thereby providing critical information for informed management decisions, environmental protection and public health safety. [Display omitted] • A XGB model to predict groundwater arsenic contamination risk in floodplains. • The co-enrichment of As with NH 4 + as a key factor influencing As concentrations. • The model demonstrates robust transferability across various floodplains. [ABSTRACT FROM AUTHOR]

Waterborne exposure to arsenic trioxide (As 2 O 3) is inevitable due to its widespread industrial and agricultural applications. Oxidative stress and cascaded programmed cell death is now hypothesized to be the dominant mechanisms of arseniasis evidenced in vivo and in vitro. This study aimed to explore the interaction of divalent zinc ion (Zn2+), an efficient reactive oxygen species (ROS) scavenger with arsenite in the heart of common carp, and extensively investigated the exact signaling molecules involved. Significant induction of cardiotoxicity including oxidative stress, apoptosis and autophagy was evident in heart tissues following arsenite exposure (P < 0.05). The dissipation of antioxidant enzymes (SOD and CAT) was induced by ROS burst, leading to oxidative damage and lipid peroxidation (MDA). Arsenite induced classic apoptotic hallmarks, characterized by chromatin degradation and subsequent formation of clumps adjacent, and elevated expression of Bax/Bcl-2 and Caspase family, and also increased autophagic flux evidenced by accelerated formation (LC3) and degradation (p62) of autophagosomes. PI3K/Akt/mTOR pathway was phosphorylated inhibited, while MAPK signaling (p38, ERK and JNK) displayed elevated phosphorylation levels in arsenite-exposed heart tissues. In contrast, above phenomena were effectively inhibited by Zn2+, which supplement attenuated arsenite-induced myocardial toxicity through inhibition of apoptosis and autophagy via PI3K/Akt/mTOR pathway, as well as suppressing intracellular ROS cluster via activating antioxidative system via MAPK pathway. Our results provided experimental explanation and evidences for cardiotoxicity of arsenite. Furthermore, our findings hint that the application of zinc preparations may provide a candidate for the prevention and treatment for arsenic poisoning. Image 1 • Arsenic cardiac accumulation induces ROS burst and collapse of antioxidant system. • Apoptosis and autophagy are induced under arsenic stress. • Zinc antagonizes cardiotoxicity of arsenic via MAPK and PI3K/Akt/mTOR pathways. [ABSTRACT FROM AUTHOR]

Microbial transformation of arsenic (As) plays a key role in As biogeochemical cycling and affects the mobility, bioavailability, and toxicity of As. This study aims to investigate the accumulation of As in marine sediments at different water depths in the East China Sea and reveal the abundance and diversity of the aioA , arrA , arsC, and arsM genes through quantitative real-time polymerase chain reaction (qPCR) and high-throughput sequencing. Results showed that the As content in sediments ranged from 5.53 mg kg−1 to 17.70 mg kg−1, which decreased with water depth. Abundant As biotransformation genes with low diversity were identified in these sediments, of which arsM and arrA were the most abundant. Significant positive correlation exists between the arsM and arrA gene abundance and between arsC and aioA , indicating the co-occurrence of the As biotransformation genes in microbes in marine sediments. Metagenomics analysis revealed that arsM gene was mainly distributed in Alphaproteobacteria , Solibactere s, Deltaproteobacteria , Clostridia , and Bacilli in these sediments. Among the sediment properties, total N, total S, C/N, and TOC were important factors that shaped the abundance profile of the genes involved in As transformation. This study provides a picture of As biotransformation genes in marine sediments from the East China Sea, which may affect As transformation and the ultimate fate of As in a marine environment. Image 1 • As content in marine sediments from the East China Sea decreased with water depth. • As biotransformation genes were analyzed by metagenomics in marine sediments. • arsM and arrA were abundant and co-existed in marine sediments. • α-, δ-Proteobacteria , Solibactere s, Clostridia , were main microbes carrying arsM. • Total N, S, C/N and TOC were important factors shaping the diversity of these genes. This study depicts the As distribution and its biotransformation genes in marine sediments from the East China Sea. [ABSTRACT FROM AUTHOR]

659 water samples from springs and wells in the Sabatini and Vicano-Cimino Volcanic Districts (central Italy) were analyzed for arsenic (As), fluoride (F−) and radon (222Rn) concentrations. Waters mostly sourced from a shallow and cold aquifer hosted within volcanic rocks, which represents the main public drinking water supply. Cold waters from perched aquifers within sedimentary formations and thermal waters related to a deep hydrothermal reservoir were also analyzed. The highest concentrations of As and F− were measured in the thermal waters and attributed to their enhanced mobility during water-rock interaction processes at hydrothermal temperatures. Relatively high concentrations of As and F− were also recorded in those springs and wells discharging from the volcanic aquifer, whereas waters hosted in the sedimentary units showed significantly lower contents. About 60% (As) and 25% (F−) of cold waters from the volcanic aquifer exceeded the maximum allowable concentrations for human consumption. Such anomalously high levels of geogenic pollutants were caused by mixing with fluids upwelling through faulted zones from the hydrothermal reservoir. Chemical weathering of volcanic rocks and groundwater flow path were also considered to contribute to the observed concentrations. Cold waters from the volcanic aquifer showed the highest 222Rn concentrations, resulting from the high contents of Rn-generating radionuclides in the volcanic units. Approximately 22% of these waters exceeded the recommended value for human consumption. A specific Quality Index (QI), comprised between 1 (very low) and 4 (very high), was computed for each water on the basis of As, F− and 222Rn concentrations and visualized through a spatial distribution map processed by means of geostatistical techniques. This map and the specific As, F− and 222Rn maps can be regarded as useful tools for water management by local authorities to both improve intervention plans in contaminated sectors and identify new water resources suitable for human consumption. Image 1 • Volcanic-sedimentary aquifers from Central Italy were analyzed for As, F− and 222Rn. • Water-rock interaction and input of thermal fluids are sources of geogenic pollutants. • High contents of geogenic pollutants were pertaining to the volcanic aquifers. • Quality Indexes (QIs) were obtained by combining the As, F− and 222Rn concentrations. • QI distribution maps can be used for water management in geogenically polluted areas. Spatial distribution maps of geogenic pollutants (As, F− and 222Rn) and quality indexes for water resources were determined in volcanic-sedimentary aquifers of central Italy for water management. [ABSTRACT FROM AUTHOR]

Only limited information is available on the effects of dissolved organic phosphorus (DOP) on arsenate (As (V)) bioaccumulation and biotransformation in organisms. In this study, we examined the influence of three different DOP forms (β-sodium glycerophosphate (βP), adenosine 5′-triphosphate (ATP), and D-Glucose-6-phosphate disodium (GP) salts) and inorganic phosphate (IP) on As (V) toxicity, accumulation, and biotransformation in Microcystis aeruginosa. Results showed that M. aeruginosa utilized the three DOP forms to sustain its growth. At a subcellular level, the higher phosphorus (P) distribution in metal-sensitive fractions (MSF) observed in the IP treatments could explain the comparatively lower toxic stress of algae compared to the DOP treatments. Meanwhile, the higher MSF distribution of arsenic (As) in M. aeruginosa in the presence of DOP could explain the higher toxicity with lower 96-h half maximal effective concentration (EC 50) values. Although we observed As (V) and P discrimination in M. aeruginosa under IP treatments with high intracellular P/ As , we did not find this discrimination under the DOP treatments. As accumulation in algal cells was therefore greatly enhanced by DOP, especially βP, given its lower transformation rate to phosphate compared to ATP and GP in media. Additionally, As (V) reduction and, subsequently, As (III) methylation were greatly facilitated in M. aeruginosa by the presence of DOP, particularly GP, which was confirmed by the higher relative expression of its two functional genes (arsC and arsM). Our findings indicate that As (V) accumulation and its subsequent biotransformation were enhanced by organic P forms, which provides new insight into how DOP modulates As metabolism in algae. Image 1 • M. aeruginosa could utilize the three DOP to sustain its growth. • As(V) and P aren't discriminated by M. aeruginosa under DOP conditions. • Arsenic accumulation were enhanced under DOP conditions especially βP. • As (V) reduction and subsequent methylation was facilitated by DOP, particularly GP. • Higher MSF of As can explain higher toxicity on algae under DOP conditions. [ABSTRACT FROM AUTHOR]

Arsenic (As) in rice grains is a serious food safety concern. Some coexisting engineered nanoparticles (ENPs) were shown to alter the accumulation and speciation of As in rice grains. However, investigation on the effects of copper oxide nanoparticles (CuO NPs), a popular ingredient in pesticides, on the uptake and accumulation of As is rare. We explored the potentially different impact of CuO NPs and corresponding Cu(II) ions on the accumulation of two As species in rice seedlings in a hydroponic system. Rice seedlings were treated with a combinations of 1 mg/L of arsenite (As(III)) or arsenate (As(V)) and 100 mg/L of CuO NPs or Cu(II) for 6 days. Both forms of Cu significantly reduced the accumulation of total As in rice tissues, with Cu(II) exhibiting significantly greater effect than CuO NPs. As speciation in rice roots was markedly affected by both forms of Cu, and the impacts were Cu-form dependent. For example, the co-existence of As(V) with CuO NPs led to a 45% decrease of As(V) in rice roots, while the co-existence of As(V) with Cu(II) caused a 47% increase in As(V) in rice roots. As speciation in rice shoots was less affected by co-present Cu than in rice roots. Co-occurring As(III) or As(V) lowered Cu concentration in rice roots by 40% and 50% in treatments with CuO NPs, but did not affect Cu content in rice roots co-exposed to Cu(II). The study confirmed the reciprocal effect of co-occurring CuO NPs or Cu(II) and As in rice paddies and highlighted the unique "nano-effect" of CuO NPs. The results alsos showed that the initial oxidation state of As plays an important role in the interactions between As and Cu. The results shed light on the current debate on the safe applications of nano-enabled agrichemicals vs. conventional metal salts in agriculture. Image 1 • CuO NPs and Cu ions lowered total arsenic accumulation in rice. • CuO NPs and Cu ions significantly reduced As(III) in rice roots. • Unique "nano-effect" was observed in the interactions of CuO NPs and As. • Synergistic toxicity between Cu pesticides and As to rice was observed. CuO NPs and Cu(II) ions displayed significant but form-dependent impacts on As accumulation in rice tissues. [ABSTRACT FROM AUTHOR]

Arsenic (As) and antimony (Sb) are considered as priority environmental pollutants and their accumulation in crop plants particularly in rice has posed a great health risk. This study endeavored to investigate As and Sb contents in paired soil-rice samples obtained from Xikuangshan, the world largest active Sb mining region, situated in China, and to investigate As speciation and location in rice grains. The soil and rice samples were analyzed by coupling the wet chemistry, laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS), synchrotron-based micro X-ray fluorescence mapping (μ-XRF) and micro X-ray absorption near-edge structure (μ-XANES) spectroscopy. The results of field survey indicated that the paddy soil in the region was co-polluted by Sb (5.91–322.35 mg kg−1) and As (0.01–57.21 mg kg−1). Despite the higher Sb concentration in the soil, rice accumulated more As than Sb indicating the higher phytoavailability of As. Dimethylarsinic acid (DMA) was the predominant species (>60% on average) in the rice grains while the percentage of inorganic As species was 19%–63%. The μ-XRF mapping of the grain section revealed that the most of As was distributed and concentrated in rice husk, bran and embryo. Sb was distributed similarly to As but was not in the endosperm of rice grain based on LA-ICP-MS. The present results deepened our understanding of the As/Sb co-pollution and their association with the agricultural-product safety in the vicinity of Sb mining area. Image 1 • The pollution conditions of sites were classified as sub-polluted (III) or clear (I). • As and Sb contents in rice decreased in the order of root > shoot > husk > grain. • DMA was the predominant species in the rice grains. • As distributed on the periphery and the endosperm of the rice grain. • Sb accumulated on the periphery of the rice grain. This work clearly investigated the metalloid behaviors in soil-plant system, further contributing to address the food safety issues around the mining areas. [ABSTRACT FROM AUTHOR]

Dietary arsenic (As) intake from food is of great concern, and developing a reliable model capable of predicting As concentrations in plant edible parts is desirable. In this study, pot experiments were performed with 16 Chinese upland soils spiked with arsenate [As(V)] to develop a predictive model for As concentrations in pepper fruits (Capsicum annum L.). Our results showed that after three months' aging, concentrations of bioavailable As (extracted by 0.05 M NH 4 H 2 PO 4) in various soils varied widely, depending on soil total As concentrations and soil properties such as soil pH and amorphous iron (Fe) contents. Furthermore, both the bioconcentration factor (BCF, denoted as the ratio of fruit As to soil As) and total As concentrations in pepper fruits were largely determined by concentrations of bioavailable As, which explained 27% and 69% variations in the BCF and fruit As concentrations, respectively. Apart from bioavailable As, soil pH and Fe contents were another two important factors influencing As accumulation in pepper fruits. Taking the three factors into account, concentrations of fruit As can be well predicted using a stepwise multiple linear regression (SMLR) analysis (R2 = 0.80, RMSE = 0.17). Arsenic species in soils and edible parts were also analyzed. Although As(V) predominated in soils (>96%), As in pepper fruits presented as As(V) (46%) and arsenite [As(III)] (39%) with small amount of methylated As (<15%). Aggregated boosted tree (ABT) analysis revealed that inorganic As concentrations in pepper fruits were determined by concentrations of bioavailable As, phosphorus (P) and Fe in soils. In contrast to inorganic As, methylated As concentrations were not correlated with those factors in soils. Taken together, this study established an empirical model for predicting As concentrations in pepper fruits. The predictive model can be used for establishing the As threshold in fruit vegetable farming soils. Image 1 • Reliable model was built to predict As content in pepper fruits by soil properties. • Amorphous Fe and soil pH drove the variation of bioavailable As in different soils. • Bioavailable As in soils controlled BCF and total As accumulation in pepper fruits. • As(V) dominated in soils (96%), but As(Ⅲ) (39%) and As(V) (46%) in pepper fruits. • Bioavailable As, P and Fe in soils regulated inorganic As content in pepper fruits. NH 4 H 2 PO 4 -extractable arsenic in soils is the key factor controlling total arsenic and inorganic arsenic accumulation in pepper fruits. [ABSTRACT FROM AUTHOR]

Arsenic (As) tends to mobilize in flooded paddy soil due to the reductive dissolution of the iron (oxyhydr)oxides to which As sorbs, resulting in elevated As accumulation in rice that poses a potential risk to the food safety and human health. Microbial sulfate reduction is an important biogeochemical process in paddy soils, but its impact on As mobilization remains poorly understood. In this study, we incubated eight As-contaminated paddy soils under flooded conditions to investigate the effect of sulfate addition on As mobility. Porewater Fe and As concentrations and As species were determined. Among the eight soils, an addition of 50 mg S kg−1 as sodium sulfate decreased porewater arsenite only in two soils, which also showed a high mobilization of Fe2+. Further experiments showed that the addition of sulfate to these two soils stimulated microbial sulfate reduction but decreased porewater concentrations of both arsenite and Fe2+. Additionally, the supply of sulfate increased the fractions of As associated with acid volatile sulfides in the solid phase and decreased As uptake by rice in pot experiments under similar conditions. The effect of sulfate addition on porewater As was diminished by the addition of molybdate, an inhibitor of sulfate reducing bacteria. These results suggest the formation of secondary FeS minerals which co-precipitate or sorb arsenite as a likely mechanism of As immobilization, which was also supported by thermodynamic modeling of the pore water. Thus, sulfate additions can immobilize As and reduce its availability to rice plants in paddy soils containing a high potential for microbial Fe reduction, providing an efficient way to mitigate the As transfer to the food chain. Image 1 • Sulfate addition decreased soluble As(III) in paddy soils with high soluble Fe2+. • Inhibition of sulfate reduction diminished the decrease in soluble As(III). • The decrease in soluble As(III) was due to the adsorption to secondary FeS. • Sulfate addition to paddy soils with high reducible Fe reduced rice grain As. Sulfate addition can reduce As mobility in paddy soils containing a high potential of microbial Fe reduction, offering a potential strategy to mitigate grain As accumulation in these soils. [ABSTRACT FROM AUTHOR]

Ubiquitous contamination of microplastics and arsenic in soil ecosystems can induce many health issues to nontarget soil organisms, and will also cause many potential threats to the gut bacterial communities of soil fauna. However, the changes in the gut bacterial communities of soil fauna after exposure to both microplastics and arsenic remain unknown. In this study, the toxicity and effects on the gut microbiota of earthworm Metaphire californica caused by the combined exposure of microplastics and arsenic were examined by using arsenic species analysis and high throughput sequencing of gut microbiota. Results showed that total arsenic and arsenic species in the earthworm gut and body tissues after exposure to combination of microplastics with arsenate (As(V)) were significantly different from that treated with As(V) alone. Microplastics lessened the accumulation of total arsenic and the transformation rate of As(V) to arsenite (As(III)). Microplastics alleviated the effect of arsenic on the gut microbiota possibly via adsorbing/binding As(V) and lowering arsenic bioavailability, thus prevented the reduction of As(V) and accumulation of total arsenic in the gut which resulted in a lower toxicity on the earthworm. The study broadens our understanding of the ecotoxicity of microplastics with other pollutants on the soil animals and on their gut microbiota. Image 1 • Arsenic exposure prominently altered the gut bacterial communities of earthworm. • Microplastics reduced arsenic accumulation in the earthworm gut and body tissues by inhibiting As(V) reduction. • Microplastics alleviated the effect of arsenic on the gut microbiota. Exposure to microplastics lowers arsenic accumulation in the gut and body tissues of earthworm, and alters gut bacterial communities of Metaphire californica. [ABSTRACT FROM AUTHOR]

In the present study, the 16S-rRNA sequencing of heavy metal-resistant and susceptible bacterial strains isolated from the industrial and agriculture soil showed resemblance with Pseudomonas taiwanensis. Based on the growth rate, two bacterial strains SJPS_KUD54 and KUD-MBBT4 exhibited 10 ppm tolerance to Arsenic and Cadmium. These two heavy metals caused, a significant increase in stress enzymes like superoxide dismutase, catalase and glutathione S-transferase activities in SJPS_KUD54 when compared to KUD-MBBT4. Following heavy metal treatment, the atomic-force-microscopy observations showed no change in the cell-wall of SJPS_KUD54, whereas the cell-wall of KUD-MBBT4 got ruptured. Moreover, the protein-profile of SJPS_KUD54 treated with heavy metals exhibited varied patterns in comparison with untreated control. In addition, the accumulation of hydroxyl, thiol and amides were found in the SJPS_KUD54 relative to its control. Furthermore, the resistant SJPS_KUD54 strain showed a remarkable bioaccumulation properties to both Arsenic and Cadmium. Thus, it is inferred that the growth rate, stress enzymes and functional-groups play a significant role in the physiological-adaption of SJPS_KUD54 during stress conditions, which is positively involved in the prevention or repair mechanism for reducing the risks caused by heavy metal stress. Image 1 • Bacterium possessing bioabsorption of heavy metals was isolated. • The impact of heavy metals on microbial growth and enzyme activities was studied. • SJPS_KUD54 strain exhibited physiological adaption to stress conditions. • IR functional group confirms the resistant strain SJPS_KUD54 to metal tolerance. • Resistant strain can be utilized for bioremediation of heavy metals and waste management. [ABSTRACT FROM AUTHOR]

This study assessed the impact on air quality and health risk by long-range transported (LRT) PM 2.5-10 - and PM 2.5 -bound metals and PAHs in Taipei City, Taiwan. Several methods with receptor aerosol measurements were used to quantify the effect of LRT. The hybrid single particle lagrangian integrated trajectory model (HYSPLIT) was used in conjunction with the potential source contribution function (PSCF) to distinguish the LRT aerosols. By using a general linear model (GLM) with a marginal mean and positive matrix fraction (PMF), this study also evaluated the annual increased level of LRT (AIR LRT) for each source contribution to the concentration and the resultant health risk of particle-bound metals and polycyclic aromatic hydrocarbons (PAHs). The LRT influenced fine-sized metals and PAHs rather than coarse-sized ones. We found that the level of PM 2.5 -bound toxic metals (Pb, Cd, and As) and PAHs (Benzo[a]pyrene and dibenzo[ a,e ]pyrene) could increase by 90% under the influence of LRT in 2014, while an AIR LRT value of 25% for the PM 2.5 mass concentration was observed. Overall, the excess cancer risk (ECR) resulting from PM 2.5 -bound metal and PAH exposures was 6.40 × 10−5 in relation to coal combustions (20.7%), traffic-related emissions (59.7%) and re-suspended aerosols (19.6%). Among these contributors, LRT-related metals and PAHs in PM 2.5 accounted for 51% of the total ECR. Image 1 • Evaluating long-range transported (LRT) PM 2.5-10 - and PM 2.5 -bound metals and PAHs. • The LRT influenced fine-sized metals and PAHs rather than coarse-sized ones. • The level of PM 2.5 -bound toxic metals and PAHs increase by 90% as a result of LRT. • The LRT-related metals and PAHs resulting in potential health risk were addressed. The impact of fine-sized metals and PAHs from long-range transport aerosol on air quality and human health risk in Taipei was evaluated. [ABSTRACT FROM AUTHOR]

The lack of efficient methods to treat As-rich biomass is a drawback for phytoremediation technology. In this study, we applied anaerobic digestion to reduce biomass and remove As from As-rich Pteris vittata biomass. P. vittata biomass including control (3.1 mg kg−1 As) and As-rich (2665 mg kg−1 As), together with positive and negative controls, was anaerobically digested at 35 °C for 35 d. Arsenic partitioning among gas, liquid and solid phases after anaerobic digestion was determined. Methane index potential assay was used to assess methane yields whereas liquid-displacement method was used to measure methane gas production. After 35 d, As partitioning in the liquid, solid and gas phases was 79, 30 and 1%, respectively. Besides, volatile solid was decreased from 91 to 12–17% total solid, while P. vittata biomass was decreased by 73–83%. Moreover, anaerobic digestion solubilized 76% As from P. vittata biomass, with 90% soluble As at 4.95 mg L−1 being recovered by As-Mg precipitation. Finally, methane production after 35 d was 197–212 L N CH 4 /kg volatile solid, showing slight As inhibition. Effective As removal from P. vittata biomass prior to disposal can improve the phytoremediation process. Image 1 • Anaerobic digestion efficiently removed As from P. vittata biomass with 2665 mg kg−1 As. • Methane yield was 197 and 212 L N CH 4 /kgVS for As-rich and control biomass. • P. vittata biomass was reduced by 66–83% for As-rich and control biomass. • Anaerobic digestion solubilized 70% As from P. vittata biomass. [ABSTRACT FROM AUTHOR]

Groundwater quality of Chandigarh was assessed by collecting 80 groundwater samples from different depths varying between 10 ft and 1200 ft. These samples were analyzed for possible contamination with metal pollutants such as Al, Cd, Co, Cr, Cu, Fe, Mo, Mg, Ni, Pb, V, Zn. Geospatial interpolation of the contaminants identified poor sanitary practices of waste management, agrarian activities, and industrial pollution as the prominent sources of groundwater contamination. Quality assessment of groundwater performed using Heavy metal Pollution Index (HPI), and Metal Index (MI) revealed HPI as a better method for health risk assessment. HPI indicate poor groundwater quality near municipal solid waste dumping sites and industrial areas of Chandigarh. The shallow aquifer was reported to be more contaminated than deeper aquifer. Further, health risk assessment of Chandigarh's groundwater indicated non-carcinogenic health impacts due to contamination of As, Cr, Co, Cd, Cu, Ni, Pb, Zn and carcinogenic health impacts from As, Cd, Cr, Cu, Pb. The study suggests that groundwater should also be regularly monitored for metal contamination as over-extraction, industrialization, disposal of municipal solid waste and informal E-waste recycling activities increases the public health risks in countries worldwide, facing similar environmental pollution problems of the groundwater. Image 1 • Shows distribution of metal pollution in groundwater of Chandigarh, India. • Shallow aquifer has higher levels of metals as compared to deeper aquifer. • Health risks are better represented by Heavy metal Pollution Index than Metal Index. • As, Cd, Cr, Cu and Pb have potential to cause carcinogenic health risks. Groundwater quality of Chandigarh, India was assessed for selected metals using geo-statistical techniques to identify the sources of contamination and to plan suitable remedial measures for emerging cities. [ABSTRACT FROM AUTHOR]

Elevated inorganic arsenic concentrations in groundwater has become a major public and environmental health concern in different parts of the world. Currently, As-contaminated groundwater issue in many countries and regions is a major topic for publications at global level. However, there are many regions worldwide where the problem has still not been resolved or fully understood due to inadequate hydrogeochemical investigations. Hence, this study evaluates for the first time the hydrogeochemical behavior of the arid and previously unexplored inland basin of Sirjan Plain, south east (SE) Iran, in order to assess the controlling factors which influence arsenic (As) mobility and its distribution through groundwater resources. Total inorganic arsenic concentration was measured using inductive-coupled plasma optical emission spectrometry (ICP-OES). Arsenic content in groundwater of this region ranged between 2.4 and 545.8 μg/L (mean value: 86.6 μg/L) and 50% of the samples exceeded the World Health Organization (WHO) guideline value of 10 μg/L in drinking water. Groundwater was mainly of Na-Cl type and alkaline due to silicate weathering, ion exchange and evaporation in arid conditions. Elevated As concentrations were generally observed under weakly alkaline to alkaline conditions (pH > 7.4). Multivariate statistical analysis including cluster analysis and bi-plot grouped As with pH and HCO 3 and demonstrated that the secondary minerals including oxyhydroxides of Fe are the main source of As in groundwater in this region. The desorption of As from these mineral phases occurs under alkaline conditions in oxidizing arid environments thereby leading to high levels of As in groundwater. Moreover, evaporation, ion exchange and saltwater intrusion were the secondary processes accelerating As release and its mobility in groundwater. Based on the results of this study, desorption of As from metal oxy-hydroxides surfaces under alkaline conditions, evaporation and intrusion of As-rich saline water are considered to be the major factors causing As enrichment in arid inland basins such as those in southeast Iran. This study proposes the regular monitoring and proper groundwater management practices to mitigate high levels of arsenic in groundwater and related drinking water wells of Sirjan Plain. Image 1 • This study reveals geogenic As of groundwater in previously unexplored Sirjan plain, Iran. • 50% of groundwater samples exceed the drinking water guideline value for As. • Groundwater is predominantly of Na-Cl type and alkaline nature. • Oxyhydroxides of Fe are the main sources of As in groundwater. • Evaporation, ion exchange and saltwater intrusion processes enhance As mobility. [ABSTRACT FROM AUTHOR]

In the present study, a screening level site-specific ecological risk assessment (ERA) was conducted on 10 abandoned metal mines in Korea to determine the ecological risk and prioritize the mines requiring further investigation. A cost-saving approach was adopted by combining both the chemical (ChemLoE) and the ecotoxicological (EcotoxLoE) lines of evidence for the evaluation of integrated risk (IR), rather than applying the full spectrum of Triad, including ecological LoE. The risk values for ChemLoE were derived by calculating the toxic pressure based on the total and 0.01 M CaCl 2 extractable metal(loid) concentrations. The risk values for EcotoxLoE were based on the mortality and reproduction of the collembolan species Paronychiurus kimi in the mine soils. A response surface model with a central composite design (CCD) was constructed to standardize the effects of soil physicochemical properties (i.e., organic matter content, clay content, and soil pH) on the reproduction of P. kimi. The predicted number of offspring was used as a reference for the calculation of risk value for reproduction. The ChemLoE and EcotoxLoE values ranged from 0.34 to 1.00 and 0.12 to 0.49, respectively, in the surveyed mines. The contribution of the ChemLoE value to the IR was higher than that of the EcotoxLoE value for all mines. Overall, two of the 10 mines were classified as high-risk soils with high IR values (IR > 0.76), but large deviations were also observed between the LoEs in these mines, suggesting the need for further studies to confirm the potential risks. The future investigations of these mines should focus particularly on providing additional evidence to reduce the degree of uncertainty for risk assessment. Image 1 • Site-specific ERAs were conducted for 10 mines in Korea. • Chemical and ecotoxicological lines of evidence were used to determine the integrated risk (IR). • An alternative approach to replacing the reference soil in bioassay was proposed. • IR value was used to prioritize the mines requiring further investigation. • Three out of 10 mines were at high risk with an IR value greater than 0.75. A screening level site-specific ecological risk assessment on 10 abandoned mines in Korea based on chemical and ecotoxicological lines of evidence. [ABSTRACT FROM AUTHOR]