Antimony contamination and its risk management in complex environmental settings: A review

Reduction of antimony bioavailability with the application of stable exogenous organic matter: a comparative study between rice straw and manure compost

Considering the widespread use of organic amendments to improve soil quality and enhance soil carbon sequestration, it is crucial to understand their impact on the bioavailability of metalloids in soils. Antimony (Sb), a priority pollutant, is particularly impacted by organic matter, yet the effects of different organic amendments-varying in stability and composition-on Sb bioavailability remain unclear. This study investigates the influence of different organic amendments, rice straw and compost, on Sb bioavailability in the rice-soil system, with rice ingestion being a major Sb exposure pathway in humans. Results show that while both amendments increased dissolved organic carbon in soil solution, their effects on Sb bioavailability differed markedly. Rice straw increased CDGT-SbIII by 13.24 %-66.63 %, whereas compost decreased CDGT-SbIII by 32.47 %-43.51 %. These differences were also reflected in Sb accumulation in rice shoots, where compost application resulted in lower Sb content. This reduction may be attributed to increased microbial genera such as Ramlibacter and Sphingomonas, which are associated with SbIII oxidation. Conversely, organic matter with low stability, prone to rapid degradation, could promote reducing soil conditions, thereby increasing SbIII concentrations. Our findings suggest that stable exogenous organic matter, such as pre-decomposed compost, is preferable for managing Sb-contaminated soils.

Crucial role of the Pht1;4 Gene in Sb(V) tolerance and uptake in Arabidopsis thaliana

There has been increasing awareness of the risks of antimony (Sb) in the environment, but the process of Sb(V) absorption by plants and its effects on plants remain unclear. This study focused on four independent T-DNA insertion mutant strains of Arabidopsis thaliana and wild-type (WT) plants to investigate their tolerance, uptake, and response to Sb(V). Compared with those of the WT, the Pht1;4 knockout mutant M-P4 presented greater tolerance to Sb(V) and lower absorption levels. The roots of the M-P4 were longer and the malondialdehyde (MDA) content in the roots of M-P4 was lower than WT (0.194 < 1.333, μM/mg FW). The amount of Sb(V) absorbed by the roots of M-P4 under Sb(V) treatment was lower than that absorbed by WT plants (by 25 %-50 %), and the levels of Sb in the stems and leaves were also lower. Moreover, the transmembrane transport ratio of Sb(V) in M-P4 was lower than that in the WT (0.748 < 0.937). The Pht1;1 knockout mutant exhibited a predominant transmembrane absorption mode for Sb(V), while gene expression data show that knocking out either Pht1;1 or Pht1;4 leads to the upregulation of the other gene. These results collectively demonstrate that the characteristics of M-P4 are due to the important role of Pht1;4 in Sb(V) transport. In summary, this study investigates the influence of several genes on plant tolerance and uptake to Sb(V) and elucidates the crucial role of the Pht1;4 gene, shedding light on the development of Sb phytoremediation strategies and Sb-resistant plants.

The release of antimony from soils surrounding the smelters in Karst Areas and its Environmental Implications

Antimony(Sb) in soil can be reintroduced into the environment through leaching processes driven by rainfall and surface runoff, raising concerns about secondary pollution. This study examined the release dynamics of Sb in carbonate-rich soils from an Sb smelting area in the karst region of southern China, aiming to elucidate the roles of pH, organic matter (OM), and geological conditions in Sb mobilization. The experiment was conducted under three different pH conditions (4.5, 6.0, and 7.5) and explores the influence of OM on the release behavior of Sb in the soil. Results indicated a characteristic release pattern for Sb in the soil solution, with an initial rapid increase, followed by a sharp decline, and a subsequent rise.The leaching rate of Sb was higher in neutral to weakly alkaline soil compared to acidic soils.The removal of soil OM enhanced Sb release by 3.21-4.09 times, with a significant inhibition rate reaching 50.01-76.86 %. The findings suggested Sb release kinetics followed a triphasic pattern consisting of rapid initial release, mid-term adsorption inhibition, and late-stage secondary release, which elucidated the underlying mechanisms of long-term leaching risks and provided a theoretical foundation for predicting contaminant dispersion. Soil OM effectively reduced Sb mobility through functional group complexation and soil aggregate formation, offering direct evidence for OM-based remediation strategies such as organic amendment applications. Neutral to weakly alkaline conditions (pH 6.0-7.5) significantly enhanced Sb release rates by promoting mineral desorption, indicating elevated contamination risks of Sb in karst region soils. This study emphasizes that priority should be given to increasing OM concentration and regulating pH buffering capacity to suppress Sb activity in karst areas, providing actionable scientific solutions for the remediation and management of Sb-contaminated sites.

A screening of metal(loid) content in conventional and compostable plastic polymers: understanding the sources and the connected environmental implications

Plastic pollution is a well-known environmental issue, yet the ecotoxicological implications are still underexplored. In this context, attention towards the characterization of chemical additives in plastics and their potential risks to both human health and ecosystems is now increasing. While significant research has been conducted on organic chemicals, data on inorganic additives (e.g., metallic compounds) remain limited. In this study, we analyzed the metal(loid) content in different types of plastics to better understand the presence of inorganic additives in these materials, their distribution across different polymer types, and their potential impacts. We investigated pristine plastic pellets, single-use plastic materials and recycled plastic pellets made from both conventional and compostable polymers. We observed a notable enrichment of metal(loid)s (particularly Ti, Al, and Zn) across a range of plastic types, especially when comparing pre-production pellets with final consumer materials, suggesting that these additives are incorporated during the final stages of production. Samples of polyethylene terephthalate displayed elevated levels of Sb, while compostable plastics exhibited specific trends related to Sn and In: they are abundant in the pellets, since they are used as catalyst in polymer production. This study provides a comprehensive comparison of metal additives in different plastic polymers and across different production phases. It highlights the need for characterizing metal(loid) content in plastic to understand the potential connected risks. Additionally, the findings underscore the role of compostable plastics as potential carriers of metal(loid)s to terrestrial and aquatic environments, raising concerns about their degradation and impact.

Environmentally relevant concentrations of antimony pose potential risks to human health: An evaluation on human umbilical vein endothelial cells

Antimony (Sb) ore exploitation and the use of Sb-containing drugs pose known health risks. This study investigated the toxicity of environmentally relevant concentrations of Sb (0.12-12 mg L-1) on human umbilical vein endothelial cells (HUVECs). The 50 % lethal concentration (LC50) of Sb to HUVECs was 11.4 mg L-1. Exposing to high level of Sb induced cell cycle arrest by altering the expression of cell cycle regulators, inhibiting the transitions of G0/G1 to S and S to G2/M. At 1.2 mg L-1 Sb, CKD6 and p21 expressions in HUVECs changed to 0.75 and 1.32 folds that of no-Sb control, respectively (p < 0.01). At 12 mg L-1 Sb, CDK2, CKD6, and p27 expressions decreased by 1.54, 4.41, and 1.54 folds (p < 0.001), while p21 expression increased by 3.03 folds (p < 0.001) as compared to control. Sb also led to cell apoptosis, evidenced by Annexin V-FITC/PI staining and changes in the expressions of Bax (1.21-1.30 folds, p < 0.01) and Bcl-2 (0.65-0.83 folds). Oxidative damage was a pivotal factor driving cell apoptosis, probably through down-regulating antioxidant genes (CAT, GPX1, and GSTP1) and up-regulating stress response genes (HO-1, SOD1, and TrxR1). The elevated H2O2 generated in mitochondria likely contributed to cell apoptosis due to the imbalance in H2O2 metabolism. These findings suggest that environmentally relevant concentrations of Sb can exert cytotoxicity to HUVECs, which should be of potential concern for human cardiovascular disease.

Ecological adaptation of antimony-oxidizing bacteria (SbOB) drives habitat-specific bioremediation potential

Antimony-oxidizing bacteria (SbOB) play vital roles in Sb detoxification, yet their environmental adaptation mechanisms remain unclear. Through comparative analysis of Sb-contaminated groundwater and soil ecosystems in Xikuangshan mining area, we revealed striking habitat-driven divergence in SbOB survival strategies, focusing on community diversity, ribosomal RNA operon (rrn) copies, niche breadth, and gene profiles. Results showed that SbOB markedly enhanced α-diversity in groundwater but minimally affected soil communities. Taxonomically, Hydrogenophaga, Pseudomonas, and Aeromonas prevailed in groundwater, whereas Acidobacteria, Chloroflexi, and Gemmatimonadaceae dominated soil ecosystems. Genomic traits revealed groundwater SbOB uniquely linked Sb oxidation (aioA) and metabolic pathways for sulfur oxidation (soxB), CO2 fixation (cbbL), and N2 fixation (nifH), enabling versatile energy acquisition. These taxa demonstrated rapid responses to fluctuating organic inputs via higher rrn copies, expanding their niche through autotrophy. Additionally, oxidative stress tolerance genes enabled them to thrive under oxygen fluctuations in groundwater. Conversely, soil SbOB with lower rrn copies prioritized antibiotic resistance for niche competition. These findings establish a habitat-specific framework for Sb bioremediation. Groundwater SbOB consortia, with their multifunctional metabolic toolkit, are prime candidates for engineering bioaugmentation systems to simultaneously detoxify Sb(III) and mitigate co-contaminants (e.g., sulfides, nitrate) in mining-impacted aquifers.

Oral bioaccessibility and probabilistic human health risk assessment of potentially toxic elements in stream sediments from an abandoned gold mine in Panama

In this study, the oral bioaccessibility of potentially toxic elements (PTEs) (As, Ba, Cu, Sb, and Zn) in river sediments from the abandoned Remance Mine was evaluated, and the associated human health risks from exposure to these contaminants through accidental ingestion during recreational activities were assessed using a probabilistic approach. The pseudo-total concentrations and bioaccessible fractions (BAF) of the selected PTEs were determined using the Unified BARGE Method (UBM), which simulates the human digestive process for both the gastric (G-phase) and gastrointestinal (GI-phase) phases. The results indicate that the BAF of PTEs was higher in the G-phase than in the GI-phase. In the G-phase, the BAF followed this decreasing order: Cu > Ba > Zn > As > Sb, while in the GI-phase, the order was Cu > Zn > Ba > As > Sb. Regarding the risk assessment, As emerged as the most significant contaminant, exceeding the safe exposure limits for both carcinogenic (CR) and non-carcinogenic (HQ) risk, mainly in children. The CR for the pseudo-total concentration was 10 times higher than in the G-phase and 18 times higher than in the GI-phase. The HQ results indicated values exceeding the safe exposure threshold only in the pseudo-total concentration. These findings highlight that the incorporation of bioaccessibility into risk assessments provides more accurate estimates. This is a novel study, the first one carried out in Panama, which investigates the oral bioaccessibility of potentially toxic elements (PTEs) in stream sediments from the Remance gold mine, an area with high concentrations of As, Cu, Zn, Sb, and Ba. Finally, the importance of managing river use in contaminated mining environments is underscored, and some recommendations are provided, aimed to make these sustainable.

Biochar Influences the Transformation and Translocation of Antimony in the Rhizosphere-Rice System

The rhizosphere is a crucial interface that connects the soil and the roots of plants, playing a critical role in regulating soil biochemical functions and processes. Biochar, an increasingly common soil amendment, can directly or indirectly affect the redistribution behavior of heavy metal(loid)s. Our study used a rice pot experiment to investigate the redistribution behavior of antimony (Sb) in the rhizosphere-rice system during the four key rice growth stages and analyze the effects of biochar (BC). Biochar increased pH, soil organic matter (SOM), and dissolved organic carbon (DOC) but decreased Eh, affecting Sb redistribution in the rhizosphere-rice system. The Sb fractions were altered with rice growth and the addition of BC. For example, bioavailable Sb increased by 1.57-32.97% in the presence of BC across all rice growth stages. Biochar reduced the BCF and TFR-S of Sb but elevated the TFS-G, indicating that biochar reduced Sb migration from the soil to the rice roots and the rice roots to shoots but increased Sb migration from rice shoots to grains. This study highlights the potential use of biochar as a reclamation agent in remediating Sb-contaminated soils and protecting human health from Sb through the food chain.

Identification of the sources and migration of antimony in karst terraces via Sb stable isotopes

The provenance and migration pathways of antimony (Sb) in karst terraced soils remain poorly constrained. This study employs Sb isotopic compositions (ε¹²³Sb values ranging from -1.91ε to 4.55ε), major-trace element geochemistry, and mass balance modeling to quantitatively resolve Sb input fluxes and translocation mechanisms in typical Guizhou karst terrace systems. The results demonstrate that approximately 67 % of the soil Sb is derived from limestone weathering, with 27 % and 6 % attributable to wet deposition and dry deposition, respectively. Within the 0-0.59 m soil layer, the Sb isotopic composition is relatively heavier (1.96ε-3.18ε), which is likely influenced by atmospheric deposition and organic matter adsorption. Within the 0.59-8.7 m soil layer, the Sb isotopic composition becomes lighter (0.17ε-2.45ε), which is attributed to the preferential adsorption of lighter Sb isotopes by iron oxides and manganese oxides. Within the 8.7 m valley bottom layer, leaching drives the migration of heavier isotopes toward the valley bottom, resulting in the heaviest Sb isotopic composition in this layer (with a maximum value of 4.55ε).

Lead source apportionment and climatic impacts in rural environmental justice mining communities

After a sequence of natural disasters in Gila County, Arizona, USA environmental justice (EJ), mining areas, community members raised concerns about metal(loid)s exposure and origin. To address these concerns, non-residential sediments (0-2 cm, 2-15 cm, and 15-30 cm), household soil (0-2 cm), and indoor and outdoor dust samples were analyzed for metal(loid)s concentration and Pb isotopes via inductively coupled plasma mass spectrometry. To identify the potential sources of Pb, 37 studies were considered, and 21 different Pb isotopic ratios were documented and compared. Spearman's correlation and principal component analysis were used to investigate the co-occurrence of metal(loid)s associated with Pb. The results demonstrated a clear association (p < 0.05) between Pb and mining activity in households and non-residential locations as well as a co-occurrence with As, Cd, Cu, Mo, Sb, and Zn at 0-2 cm and in non-residential with As, Cd, and Zn at 2-15 cm and 15-30 cm. The outdoor household dust was impacted by a mixture of Pb sources and was associated with metal(loid)s coming from mining, wildfire, lead based-paint and landfill, whereas indoor Pb dust was associated mainly with metal(loid)s coming from geogenic sources. Further, 66% of town/city sediment samples across depth and 53.8% of outdoor dust samples were aligned with mining fingerprint and 30.1% of outdoor dust and 25% of household soil samples were aligned with the wildfire Pb isotopic ratio/fingerprint. The Positive Matrix Factorization model illustrates flood's ability to remobilize metal(loid)s from neighboring mine sites to the households' locations. Currently there is no established Pb isotopic ratio composition for wildfires in Arizona; this study lays the foundation for understanding the complex relationship between the myriads of lead sources in our environment, wildfires, and flooding.

Assessment the impact of palygorskite modified by chlorides on speciation and environmental risk of heavy metals in soil contaminated

This study aims to evaluate the effectiveness of palygorskite (PAL) modified with various chlorides (PMNaCl), (PMCaCl2), (PMMgCl2), (PMFeCl3) and (PMAlCl3) in stabilizing Cu and Ni in contaminated soils. Characterization methods involving Scanning Electron Microscopy (SEM), X-ray deflection (XRD and Fourier Transform Infrared Spectroscopy (FT-IR) were used to characterize the effects of palygorskite on the chemical functional groups of chloride stick and the construction of stabilizers. The Diethylene Triamine Pentaacetic Acid ("DTPA extraction") and Toxicity Characteristic Leaching Procedure (TCLP) were conducted to assess the bioavailability and mobility of Cu and Ni in soil with PAL-modified chlorides. The germinated index (GI) was employed to examine and analyze the microstructure and physico-chemical properties of the contaminated soil. The residue speciation concentration enhanced substantially, illustrating that the heavy metal speciation had stabilized after being with PAL-modified chloride. After the amendment of the PAL-modified chlorides the soil pH was enhanced by 1.33 units, whereas Electrical Conductivity (EC) increased significantly (P < 0.05) from 2.61 to 4.95 µS cm-1, Cation Exchange Capacity (CEC) increased significantly (P < 0.05) from 11.50 to 13.00 cmol/kg, while the available potassium (K) was significantly (P < 0.05) increased from 51.67 to 69.30, and the available phosphate (P) was significantly (P < 0.05) increased from 0.38 to 0.63. The most significant Sequential Extraction Procedure (BCR) in residual fraction for Cu and Ni in soil treated by PMFC and PMMC were significantly (P < 0.05) increased by 37.37% and 39.33%, respectively. Our findings indicate that PAL-modified chlorides significantly stabilize heavy metals in soil, making them promising candidates for soil remediation.

Efficient adsorption of Sb(III/V) by zirconium-functionalized cellulose microspheres and their application in actual underground water of mine cavern

At present, with the mining of antimony, highly toxic antimony has seriously threatened the safety of water sources and jeopardized human health. It remains a challenge to create adsorbents that are easy to separate, efficient and have high adsorption capacity. In this study, the zirconium-functionalized MCC microspheres (MCC-g-GMA-IDA-ZrOCl2) have been successfully synthesized using radiation grafting technique and applied for Sb(III/V) capture. Batch systematic adsorption experiments indicate that the experimental data for Sb(III/V) conform to the pseudo-second-order kinetic model with Langmuir maximum adsorption capacities of 56.25 mg/g (Sb(III)) and 240.96 mg/g (Sb(V)), respectively. Combining XPS and FTIR characterization with experimental data, it is reasonable to assume that MCC-g-GMA-IDA-ZrOCl2 removes antimony from aqueous solutions by ligand exchange, electrostatic attraction and surface complexation mechanisms. Column experiments demonstrate that MCC-g-GMA-IDA-ZrOCl2 selectively traps Sb(III/V) in underground water of mine cavern. Through the above adsorption performance tests, MCC-g-GMA-IDA-ZrOCl2 is expected to treat Sb(III/V) in antimony contaminated groundwater on a large scale in industrial water.

Groundwater arsenic and antimony mobility from an antimony mining area: Controls of sulfide oxidation, carbonate and silicate weathering, and secondary mineral precipitation

Sulfide mineral oxidation has been recognized as the key driver of arsenic (As) and antimony (Sb) mobility in mining-impacted groundwater. However, the role of carbonate and silicate weathering and secondary mineral precipitation in this process remain unknown. A comprehensive geochemical study of groundwater was conducted in an Sb-mining area, Hunan, China, with samples collected from aquifers of the Xikuangshan Formation (D3x), the Shetianqiao Formation (D3s ), and the Lower Carboniferous Formation (C1y). Results show co-enrichment of dissolved As and Sb with concentrations reaching up to 28.8 and 22.1 mg/L, respectively. The significant positive correlation between SO42- and As or Sb concentrations, coupled with the similarity of δ34S-SO4 to δ34S signature of sulfide minerals (e.g., arsenopyrite and stibnite), indicate sulfide mineral oxidation as the primary mobilization mechanism. The significantly higher SO42- concentrations support more extensive sulfide mineral oxidation in the D3s aquifer than those in the D3x and C1y aquifers, which was responsible for its significantly higher As and Sb concentrations. The SO42-/Σ+ against Ca2+/Σ+ cross plot suggests that, in addition to sulfide mineral oxidation, silicate weathering was more prevalent in the D3s groundwater, which may contribute to enhance As and Sb mobility. However, carbonate dissolution triggered by sulfide mineral oxidation dominated in the C1y groundwater with significantly higher Ca2+/Σ+, favoring the precipitation of pharmacolite (CaHAsO4:2H2O) and Ca2Sb2O7, which acted as important sinks for dissolved As and Sb. This study highlights that, in addition to sulfide mineral oxidation, the carbonate and silicate weathering and precipitation of As and Sb-bearing minerals are also pivotal in influencing the As and Sb mobility in groundwater from a mining area.

Antimony release from e-waste-derived microplastics in aqueous environments: Effect of plastic properties and environmental factors

Antimony (Sb) is an emerging contaminant widely concerned by researchers recently. Sb2O3, the flame-retardant synergist extensively used in plastics for electronic products, is an important source of Sb pollution. It can be released into the environment from e-waste, especially from the formed microplastics (MPs). However, the behavior and mechanisms of Sb release remain unclear. This study investigated the release behavior of Sb from two typical e-waste-derived MPs, acrylonitrile-butadiene-styrene (ABS) and high-impact polystyrene (HIPS). The effects of particle size, plastic aging, and environmental conditions (pH, humic acid, and inorganic ions) on Sb release were explored. It was found that HIPS exhibited higher total Sb (Sbtot) release than ABS, due to differences in their hydrophilicity and crystallinity. When the particle size was reduced from 2 mm to 0.15 mm, Sbtot release from HIPS and ABS increased by 620% and 350%. UV aging increased hydrophilicity and decreased crystallinity of MPs, further enhancing Sbtot release. Notably, there were about 40% Sb(III) in Sbtot released by pristine MPs, whereas in the leachate from the UV-aged MPs, Sbtot was exclusively Sb(V). Sbtot release was greatly enhanced by acidic and alkaline environments, especially at extreme pH levels, while humic acid has an inhibitory effect on the Sbtot release. These results suggest considerable amounts of Sb can be released into the environment from e-waste-derived MPs, and affected by various environmental factors. These findings improve understanding of Sb release from MPs in e-waste areas under various environmental conditions, providing insights into environmental risks tied to additive release from MPs.

Simultaneous alleviation of antimony toxicity in rice and in-Vitro bio-accessibility by using biochar and seaweed based fertilizer blend

Antimony (Sb) toxicity is a significant threat to crop production and humans. Its concentration is increasing in soil and water due to human activities which needs dire attention to address this challenge. Biochar is a promising amendment to remediate polluted soils, however, its role in mitigating the toxic impacts of Sb on plants is still unclear. Seaweed-based fertilizer (SBF) has shown appreciable results in improving plant performance, however, its role against metal/metalloids toxicity has not been studied yet. Therefore, this study tested the impacts of BC and SBF in mitigating the harmful effects of Sb on rice. The study was carried out with the following treatments; control, Sb stress (600 mg kg-1), Sb stress + biochar (2%), Sb stress + seaweed-based fertilizer (SBF: 2%), and Sb stress + BC (1%) and SBF (1%). The results showed that Sb toxicity adversely affected rice growth and productivity by impeding photosynthetic pigments, leaf relative water contents, increasing production of oxidative stress biomarkers (electrolyte leakage: EL, hydrogen peroxide: H2O2, malondialdehyde: MDA), and accumulation of Sb in plant parts. Contrarily, BC and SBF blends mitigated Sb-induced growth and yield damages in rice by improving photosynthetic efficiency, osmolyte synthesis, nutrient uptake, soil enzymatic activity, and antioxidant activities. Moreover, BC and SBF blend also reduced the bio-accessible Sb concentration (95.63%), bio-accessibility of Sb (25.40%), Sb transport coefficient (35.70%) and soil Sb antimony concentration (52.74%). Given these findings, the co-application of BC and SBF showed a profound improvement in rice yield by regulating photosynthetic performance, antioxidant activities, oxidative stress markers, antioxidant activities, and soil properties.

Standardized framework for assessing soil quality at antimony smelting site by considering microbial-induced resilience and heavy metal contamination

Antimony smelting activities damage the soil and vegetation surroundings while generating economic value. However, no standardized methods are available to diagnose the extent of soil degradation at antimony smelting sites. This study developed a standardized framework for assessing soil quality by considering microbial-induced resilience and heavy metal contamination at Xikuangshan antimony smelting site. The soil resilience index (SRI) and soil contamination index (SCI) were calculated by Minimum Data Set and geo-accumulation model, respectively. After standardized by a multi-criteria quantitative procedure of modified Nemerow's pollution index (NPI), the integrated assessment of soil quality index (SQI), which is the minimum of SRINPI and SCINPI, was achieved. The results showed that Sb and As were the prominent metal(loid) pollutants, and significant correlations between SQI and SRI indicated that the poor soil quality was mainly caused by the low level of soil resilience. The primary limiting factors of SRI were Fungi in high and middle contaminated areas, and Skermanella in low contaminated area, suggesting that the weak soil resilience was caused by low specific microbial abundances. Microbial regulation and phytoremediation are greatly required to improve the soil quality at antimony smelting sites from the perspectives of pollution control and resilience improvement. This study improves our understanding of ecological effects of antimony smelting sites and provides a theoretical basis for ecological restoration and sustainable development of mining areas.

Remediation of antimony and arsenic in co-contaminated soil by electrolytic manganese residue-biochar composite: Effects, mechanisms, and microbial response

Antimony (Sb) mining and smelting activities caused Sb and arsenic (As) pollution in the soil, posing a threat to the ecosystem and human health. To remediate Sb and As in co-contaminated soil and realize the resource utilization of typical industrial solid waste, electrolytic manganese residue (EMR)-biochar composite (EB) was prepared from EMR and distillers grains by a facile one-step pyrolysis method. The immobilization effect of EB on Sb and As in soil was studied using a column leaching experiment. Pot and soil incubation experiments were conducted to investigate the effects of EB on the bioavailability of Sb/As and microbial communities. The results showed that 4 wt% EB treatment reduced the accumulated contents of Sb and As in leachates by 29.21%-55.65% and 53.51%-68.95%, respectively, compared with the control. EB treatment (1 wt%) improved plant height, root length, phytomass, and chlorophyll content of Brassica campestris L. Compared to the untreated soils, 4 wt% EB treatment increased the well-crystallized hydrous oxides and residual fractions of Sb and As by 4.29%-6.23% and 4.09%-7.03%, respectively. The concentrations of bioavailable Sb and As in soil were reduced by 48.01%-71.92% and 52.31%-53.81%, respectively. EB interacted with As/Sb-resistant dominant microorganisms such as Proteobacteria in the soil, promoted their growth, and enhanced the immobilization of Sb/As. EB increased the relative abundance of redox-related bacteria of Sb and As (Thiobacillus and Sulfuriferula) by affecting soil EC and bioavailable Sb/As. The immobilization of As and Sb by EB include complexation, hydrogen bonding, and pore filling. These findings provide novel insights into the remediation of Sb and As co-contaminated soils.

Mechanism of removal of Sb from printing and dyeing wastewater by a novel titanium-manganese binary oxide

Antimony (Sb) is a toxic heavy metal that endangers both the environment and human health. In response to the growing need for efficient Sb removal from printing and dyeing wastewater (PDW), this study introduces a novel titanium-manganese binary oxide adsorbent (T2M1BO) synthesized via precipitation. Experimental results show that T2M1BO exhibited higher absorption efficiency for Sb(III) compared to Sb(V), with maximum adsorption capacities recorded at 323.19 mg/g for Sb(III) and 273.65 mg/g for Sb(V) at pH 5. The findings emphasize the synergistic interaction between titanium and manganese oxides, which enhances the adsorption of antimony. Adsorption followed a pseudo-second-order kinetic model, consistent with the Freundlich isotherm model. While Sb(V) adsorption involved surface metal hydroxyl group replacement and inner-sphere complex formation, Sb(III) removal required a more complex approach, incorporating adsorption and oxidation processes. The straightforward synthesis, high efficiency, and recyclability of T2M1BO position it as a cpromising candidate for antimony removal in recyclability wastewater treatment.

Boron contributes to enhance antimony tolerance in rice (Oryza sativa L.) by activating antioxidant system, modifying the cell wall component and promoting cell wall deposition of Sb

Boron (B) is essential for plant growth and helps mitigate metal toxicity in various crop plants. However, the potential role and underlying mechanisms of B in alleviating antimony (Sb) toxicity in rice remain unexplored. In this study, we investigated the effects of H₃BO₃ supplementation (30, 50, and 75 μM) on morphological growth, physiological and biochemical traits, Sb content, and the subcellular distribution of Sb in rice plants under 100 μM Sb stress during the seedling stage in a hydroponic system. The results revealed that Sb toxicity severely impaired rice growth, reducing shoot biomass by 38.3%, shoot and root length by 38.9% and 23.2%, and leaf relative water content by 15.5%. Supplementation with 30 μM B mitigated these adverse effects by enhancing photosynthesis and chlorophyll synthesis, restoring root activity, and improving oxidative balance through increased antioxidant enzyme activities in rice tissues. Furthermore, B supplementation significantly reduced Sb concentration in roots by 56.28%, while promoting Sb distribution in the cell wall (CW) fraction. Scanning electron microscopy equipped with energy-dispersive X-ray (SEM-EDS) microanalysis confirmed that B enhanced Sb adsorption on root CWs. Fourier transform infrared spectroscopy (FTIR) analysis indicated increased carboxyl groups in the CWs following B application under Sb treatment. Moreover, B supplementation increased the levels of pectin and hemicellulose and elevated pectin methylesterase (PME) activity by 22.0%, 69.0%, and 29.0% in roots, respectively, thus promoting Sb chelation onto the CWs. Taken together, our results provide a scientific basis and theoretical guidance for applying B to alleviate Sb toxicity in crops.

Removal of Antimony(V) from aqueous solutions by electrodeionization

This study investigates the removal efficiency of the toxic element antimony (Sb(V)) using a combined system incorporating ion exchange resins and ion exchange membranes to form an Electrodeionization (EDI) cell. The impact of various operational parameters, including applied potential, flow rate, Na₂SO₄ concentration in the electrode compartment, and the presence of interfering ions, on Sb(V) removal was systematically examined. Results indicate that increasing the applied potential significantly enhances Sb(V) removal, achieving a maximum removal rate of 99% at 40 V and 50 V, with the residual Sb(V) concentrations reducing to 60 μg/L and 9 μg/L, respectively. Variation in flow rate from 1 L/h to 3 L/h showed that removal efficiency peaks at 99% for flow rates of 2 L/h and above. Adjusting the Na₂SO₄ concentration from 0.005 M to 0.05 M in the electrode compartment also improves removal efficiency, maintaining a rate of 99%. Furthermore, the presence of low concentrations of Cl⁻, SO₄2⁻, NO₃⁻, and PO₄³⁻ ions resulted in achieving a 99% removal efficiency of Sb(V). These findings demonstrate the system's robustness and potential for effective Sb(V) removal from aqueous solutions under varying operational conditions.

Mechanism of extracellular electron transport and reactive oxygen mediated Sb(III) oxidation by Klebsiella aerogenes HC10

Microbial oxidation and the mechanism of Sb(III) are key governing elements in biogeochemical cycling. A novel Sb oxidizing bacterium, Klebsiella aerogenes HC10, was attracted early and revealed that extracellular metabolites were the main fractions driving Sb oxidation. However, linkages between the extracellular metabolite driven Sb oxidation process and mechanism remain elusive. Here, model phenolic and quinone compounds, i.e., anthraquinone-2,6-disulfonate (AQDS) and hydroquinone (HYD), representing extracellular oxidants secreted by K. aerogenes HC10, were chosen to further study the Sb(III) oxidation mechanism. N2 purging and free radical quenching showed that oxygen-induced oxidation accounted for 36.78% of Sb(III) in the metabolite reaction system, while hydroxyl free radicals (·OH) accounted for 15.52%. ·OH and H2O2 are the main driving factors for Sb oxidation. Radical quenching, methanol purification and electron paramagnetic resonance (EPR) analysis revealed that ·OH, superoxide radical (O2•-) and semiquinone (SQ-•) were reactive intermediates of the phenolic induced oxidation process. Phenolic-induced ROS are one of the main oxidants in metabolites. Cyclic voltammetry (CV) showed that electron transfer of quinone also mediated Sb(III) oxidation. Part of Sb(V) was scavenged by the formation of the secondary Sb(V)-bearing mineral mopungite [NaSb(OH)6] in the incubation system. Our study demonstrates the microbial role of oxidation detoxification and mineralization of Sb and provides scientific references for the biochemical remediation of Sb-contaminated soil.

Priority sources identification and risks assessment of heavy metal(loid)s in agricultural soils of a typical antimony mining watershed

Heavy metal(loid) (HM) pollution in agricultural soils has become an environmental concern in antimony (Sb) mining areas. However, priority pollution sources identification and deep understanding of environmental risks of HMs face great challenges due to multiple and complex pollution sources coexist. Herein, an integrated approach was conducted to distinguish pollution sources and assess human health risk (HHR) and ecological risk (ER) in a typical Sb mining watershed in Southern China. This approach combines absolute principal component score-multiple linear regression (APCS-MLR) and positive matrix factorization (PMF) models with ER and HHR assessments. Four pollution sources were distinguished for both models, and APCS-MLR model was more accurate and plausible. Predominant HM concentration source was natural source (39.1%), followed by industrial and agricultural activities (23.0%), unknown sources (21.5%) and Sb mining and smelting activities (16.4%). Although natural source contributed the most to HM concentrations, it did not pose a significant ER. Industrial and agricultural activities predominantly contributed to ER, and attention should be paid to Cd and Sb. Sb mining and smelting activities were primary anthropogenic sources of HHR, particularly Sb and As contaminations. Considering ER and HHR assessments, Sb mining and smelting, and industrial and agricultural activities are critical sources, causing serious ecological and health threats. This study showed the advantages of multiple receptor model application in obtaining reliable source identification and providing better source-oriented risk assessments. HM pollution management, such as regulating mining and smelting and implementing soil remediation in polluted agricultural soils, is strongly recommended for protecting ecosystems and humans.

Toxicity of antimony in housefly after whole-life-cycle exposure: Changes in growth, development, redox homeostasis, mitochondrial function, and fecundity

The increasing utilization of antimony (Sb) in manufacturing industries has led to the emergence of Sb contamination in the environment as a significant public health concern. To elucidate the toxicity of Sb and its mechanism of action, this study aimed to investigate the adverse effects of Sb on a cosmopolitan insect, housefly (Musca domestica), under a whole life cycle (from embryonic to adult stage) exposure through the examination of a suite of parameters, including biological, physiological, behavioral, and molecular endpoints. A range of Sb concentrations, including moderate contamination (0.07 mM), heavy contamination (0.7 mM), and extreme contamination (7 and 70 mM), were conducted in the study. The results indicated that the houseflies could maintain their health when exposed to 0.07 mM Sb. The exposure of Sb (0.7-70 mM) to houseflies resulted in a range of adverse effects, including developmental retardation, locomotor inhibition, gut damage, oxidative stress, and mitochondrial dysfunction in the houseflies. Significantly, Sb demonstrated reproductive toxicity in the houseflies, as evidenced by reduced reproductive capacity, DNA damage, and ovarian abnormalities. The disturbance of hormonal synthesis and the MAPK pathway induced by Sb treatment may contribute to reproductive toxicity. These comprehensive toxicological data provide insight into the prediction of toxicity and the assessment of the ecological risk of Sb.

Genome Deletions and Rewiring of the Transcriptome Underlying High Antimonite Resistance in Achromobacter sp. SMAs-55

Microbes have been shown to adapt to stressful or even lethal conditions through displaying genome plasticity. However, how bacteria utilize the ability of genomic plasticity to deal with high antimony (Sb) stress has remained unclear. In this study, the spontaneous mutant strain SMAs-55 of Achromobacter sp. As-55 was obtained under antimonite (Sb(III)) stress. SMAs-55 displayed significantly increased Sb(III) resistance, but it lost the ability to oxidize arsenite (As(III)) by deleting an entire gene island containing genes encoding functions involved in As(III) oxidation, arsenic (As)/Sb resistance and phosphate transport. This study suggests that genetic plasticity has played an important role in As-55 adaption to Sb(III) stress. Transcriptomic analysis found that genes encoding functions involved in capsule polysaccharide synthesis, as well as functions correlated to stress adaptation, ATP production, and metabolism were more strongly expressed in SMAs-55. In addition, a lower intracellular Sb(III) accumulation in SMAs-55 was observed. These findings indicate that reduced uptake through increased capsule biosynthesis was an effective way for SMAs-55 to adapt to an environment displaying high levels of Sb. This study helps us to better understand the evolutionary processes enabling survival of microbes and microbial community in contaminated environments.

Evaluating the influence of alternating flooding and drainage on antimony speciation and translocation in a soil-rice system

The quantitative evaluation of antimony (Sb) accumulation in rice has garnered significant attention due to the potential risks to human health. A pot experiment was conducted to investigate the essential nodes of Sb transfer in soil-rice system. Seven step extract results showed that during the flooding period, organic matter releasing was the primary factor contributing 14.1 % to the increase in Sb availability, while weakly crystallized Fe-Mn oxides and sulfides respectively accounted for 6.9 % and 1.42 %. During the drainage period, a notable increase in active Sb was observed, coinciding with decrease in Fe-Mn oxides and sulfides bond Sb. The migration rate constant of Sb from the root to the above-ground parts increased dramatically during the early flooding stage, being 2000 times higher than that in the mid-to-late stage. The shoot-to-grain migration rate constant remained low, at 1.07 × 10-2 d-1 and 3.52 × 10-3 d-1 during the flooding and drainage periods, respectively. Consequently, Sb accumulation amount in the grain (11.5 μg) was 2.2 times and 6.24 times lower than that in the roots and shoots, respectively. This study quantitatively evaluates the key processes controlling Sb transformation, uptake and translocation throughout different growth stages of the rice plant.

Integrative application of biochar and bacteria for mitigating antimony toxicity and bio-accessibility in sorghum

Antimony (Sb) toxicity is a serious concern due to its harmful effects on humans and plants. Biochar (BC) has become a popular amendment for remediating soils polluted with metals and metalloids. However, the exact interaction mechanism between BC, and microbes to remediate Sb-polluted soils remains unclear. To address this, a study was performed to determine the impacts of maize straw BC and a bacterial strain (Pseudomonas frederiksbergensis: PF) in mitigating the harmful effects of Sb toxicity on sorghum productivity. A pot experiment was set up with the following treatments: control, soil contaminated with Sb (1000 mg kg-1), Sb-contaminated soil + BC (2 %), Sb-contaminated soil + PF, and Sb-contaminated soil + BC (2 %) + PF. Antimony toxicity significantly reduced sorghum biomass and grain yield while increasing hydrogen peroxide (H2O2: 32.63 %), malondialdehyde (MDA: 68.96 %) reducing chlorophyll a (95.65 %) and chlorophyll b synthesis (92 %), increasing Sb accumulation in plant parts and decreasing soil NPK (24.48 %, 8.01 % and 19.24 %) availability, soil organic carbon (SOC: 16.36 %), microbial biomass carbon (MBC: 10.80 %) and soil urease (76.31 %) and catalase (130.52 %) activity. The combined application of BC and bacteria enhanced the sorghum biomass and grain production by improving chlorophyll synthesis, antioxidant activity, osmolyte production, nutrient availability, SOC, MBC, soil enzymatic activities and reducing both H2O2 and MDA production. Co-application of BC and bacteria decreased soil Sb concentration by 38.84 % while they decreased Sb concentration in sorghum root, stem, leaves and grains by 54.58 %, 34.15 %, 30.96 % and 54.58 % respectively. The decrease of Sb concentration in soil and plant parts with BC and bacteria application was attributed to increase in soil pH, SOC, MBC, enzymes activities. Additionally, BC in combination with bacteria also reduced bio-accessible Sb concentration by 83.82 %, and bio-accessibility of Sb by 36.45 % indicating their appreciable potential to produce safer sorghum production in highly polluted Sb soils. Therefore, BC and PF can be used together to improve sorghum production and develop environmentally friendly approaches in Sb-contaminated soils.

Antimony-bearing schwertmannite transformation to goethite: A driver of antimony mobilization in acid mine drainage

Antimony(V) mobility in acid mine drainage (AMD) is often controlled by sorption and coprecipitation with schwertmannite - a poorly-ordered Fe(III) oxyhydroxysulfate mineral. However, due to its metastable nature, schwertmannite transforms over time to more thermodynamically stable Fe(III) phases, such as goethite. This study examines how transformation of Sb(V)-bearing schwertmannite to goethite impacts Sb(V) mobility, while also assessing the role that Sb(V) may play in stabilizing schwertmannite against such transformation. To address these aims, Sb(V)-free, Sb(V)-sorbed and Sb(V)-coprecipitated schwertmannite were allowed to undergo partial transformation to goethite under acid sulfate conditions. Iron K-edge EXAFS spectroscopy revealed that sorbed and coprecipitated Sb(V) partly stabilized schwertmannite against transformation. The onset of schwertmannite transformation to goethite was found to drive clear mobilization of Sb(V) into solution, regardless of the Sb(V) loading or whether Sb(V) was initially sorbed or coprecipitated with the precursor schwertmannite. This initial phase of Sb(V) mobilization was followed by subsequent solid-phase recapture of the released Sb(V), with Sb K-edge EXAFS spectroscopy revealing that this process involved Sb(V) incorporation into the newly-formed goethite. Our findings show that, although schwertmannite transformation to goethite is partially inhibited by co-existing Sb(V), the initial stage of this transformation process drives significant Sb(V) mobilization in AMD systems.

Selenium increases antimony uptake in As-hyperaccumulators Pteris vittata and Pteris cretica by promoting antimonate reduction: GSH-GSSG cycle and arsenate reductases HAC1/ACR2

Selenium-enhanced arsenic uptake by As-hyperaccumulators Pteris vittata and Pteris cretica is known, but how it impacts antimony (Sb) uptake and associated mechanisms are unclear. Here, we investigated the effects of 2.5 μM selenate (Se2.5) on Sb uptake by two plants after growing for 10 days under hydroponics containing 10 or 50 μM antimonate (SbV) (Sb10 or Sb50). Both plants were efficient in taking up SbV, which was reduced to SbIII (17-40 %) and mainly accumulated in the roots (86-97 %). The addition of Se increased the Sb contents by 78-97 and 29-33 % to 242-1358 and 132-697 mg kg-1 in P. vittata and P. cretica roots. Compared with the Sb10 and Sb50 treatments, addition of Se increased the SbV reduction, with more increase in P. vittata than P. cretica roots (181-273 % vs. 17-29 %). Enhanced GSH-GSSG cycle mediated by glutathione peroxidase (GPX) and glutathione reductase (GR) may play an important role in SbV reduction in the roots. Compared with the Sb treatments, addition of Se increased the GPX and GR activity by 71-97 and 2-50 % in P. vittata roots, and 59-153 and 22-63 % in P. cretica roots. Besides, Se upregulated the expression of arsenate reductases PvHAC1 and PvACR2 in P. vittata roots by 1.7-3.4 folds but not in P. cretica. Se-enhanced SbV reduction in P. vittata explains why it was more effective in Sb accumulation than P. cretica. Taken together, Se is effective in increasing the Sb uptake in both plants probably by promoting SbV reduction via GSH-GSSG cycle and/or PvHAC1/PvACR2, suggesting that Se may be used to enhance phytostabilization of Sb-contaminated soils.

Antimony(V) sorption and coprecipitation with ferrihydrite: An examination of retention mechanisms and the selectivity of commonly-applied extraction procedures

We investigated the mechanisms that control Sb(V) sorption and coprecipitation with ferrihydrite across a range of Sb(V) loadings, and examined the associated effects on Sb(V) extractability during the commonly-applied 1 M HCl extraction scheme and the BCR and Wenzel sequential extraction schemes. EXAFS spectroscopy reveals that Sb(V) sorption and coprecipitation mainly involved Sb(V) incorporation into the ferrihydrite structure via edge sharing and double-corner sharing between SbO6 and FeO6 octahedra. Large amounts of these linkages partially stabilized ferrihydrite against extraction with 1 M HCl. Negligible (< 0.5 %) ferrihydrite-bound Sb(V) was recovered in the "acid extractable" and "reducible" fractions of the BCR scheme, while 1-16 % was recovered in the "oxidizable" fraction. As such, the BCR scheme risks ferrihydrite-bound Sb(V) being misidentified as Sb residing mainly in "residual" phases. In contrast, in the Wenzel scheme, almost all sorbed- and coprecipitated-Sb(V) was recovered in the "amorphous hydrous oxide-bound" fraction, with only 0.6-3.3 % in the "specifically-bound" fraction (consistent with our finding of Sb(V) retention via incorporation into ferrihydrite, as opposed to adsorption by the ferrihydrite surface). Collectively, the results provide new insights into the retention mechanisms and extraction behaviour of ferrihydrite-bound Sb(V), enhancing our ability to assess Sb contamination in soils, sediments and geogenic wastes.

Uptake, accumulation and gene response of Sb(Ⅴ) in Arabidopsis thaliana

Antimony (Sb) is a toxic pollutant, with Sb(V) being one of its main forms in the environment, but the process and mechanism of plant uptake of Sb(V) remain unclear. To investigate the process of Sb(V) uptake by plants, Arabidopsis thaliana plants were exposed to water culture media supplemented with different Sb(V) concentrations. The distribution, content, and forms of Sb(V) in Arabidopsis roots, and the accumulation and fixation of Sb(V) in Arabidopsis plants were studied. In addition, inhibitor experiments and analyses of gene expression changes were conducted to elucidate the underlying mechanism of its toxicity. Sb(V) entering the roots was mainly adsorbed on the cell wall, and the Sb(V) content in both apoplastic solution and symplastic solution increased with increasing external Sb(V) concentration. Sb(V) concentration in apoplast and symplast were approximately linearly correlated (R2=0.980), indicating low affinity of cells for Sb(V) absorption. Moreover, uncouplers significantly inhibited the entry of Sb(V) into the symplast, suggesting that the transmembrane transport of Sb(V) is energy-consuming. Sb(V) entering the cell could be partially reduced to Sb(III), and significant changes in glutathione metabolism gene expression were detected, indicating the important role of glutathione metabolism in the detoxification of Sb(V). From the perspective of the whole plant, although Sb(V) is absorbed by the roots, it is mainly fixed in the leaves and stems. This study revealed the pattern of Sb(V) uptake by plants and elucidated the mechanism of Sb(V) uptake by plants from the perspectives of kinetics, physiology, and genetics.

Soil amendment-assisted phytoremediation with ryegrass offers a promising approach to mitigate environmental health concerns

This study aimed to examine the potential of soil amendment-assisted phytoremediation using ryegrass in reclaiming abandoned gold mine soil in southwestern Ghana, with a specific focus on the soil contamination hazards associated with metals and metalloids. A pot experiment lasting 60 days was carried out to assess the efficacy of soil amendments, such as compost, iron oxide, and poultry manure, in mitigating environmental hazards. Three soil contamination indices (soil contamination = CF, enrichment factor = ER, and pollution load index = PLI) were used to calculate the extent of soil contamination, enrichment, and pollution of the sites with Co, Hg, Ni, Mo, Se, Sb, and Pb. The findings show that Hg made the greatest contribution (with a maximum soil CF of 18.0) to the overall PLI, with a maximum value of 74.4. The sites were averagely and consequently enriched with toxic elements in the decreasing order: Ni (ER = 33.3) > Mo (20.5) > Sb (14.1) > Pb (11.0) > Hg (7.9) > Se (2.1). The bioaccumulation factor (BCF > 1) suggests that ryegrass has the ability to phytostabilize Co, Hg, Mo, and Ni. This means that the plant may store these elements in its roots, potentially decreasing their negative effects on the environment and human health. Ultimately, the addition of combined manure with iron oxides might have augmented the sequestration of these metals in the root. The elements may have accumulated through sorption on manure or Fe surfaces, dissolution from watering the plants in the pot, or mineralization of organic manure. Thus, ryegrass has shown potential for phytostabilisation of Co, Hg, Mo, and Ni when assisted with a combination of manure and iron oxides; and can consequently mitigate the environmental and human health impacts.

Zeolites in wastewater treatment: A comprehensive review on scientometric analysis, adsorption mechanisms, and future prospects

Zeolites possess a microporous crystalline structure, a large surface area, and a uniform pore size. Natural or synthetic zeolites are commonly utilized for adsorbing organic and inorganic compounds from wastewater because of their unique physicochemical properties and cost-effectiveness. The present review work comprehensively revealed the application of zeolites in removing a diverse range of wastewater contaminates, such as dyes, heavy metal ions, and phenolic compounds, within the framework of contemporary research. The present review work offers a summary of the existing literature about the chemical composition of zeolites and their synthesis by different methods. Subsequently, the article provides a wide range of factors to examine the adsorption mechanisms of both inorganic and organic pollutants using natural zeolites and modified zeolites. This review explores the different mechanisms through which zeolites effectively eliminate pollutants from aquatic matrices. Additionally, this review explores that the Langmuir and pseudo-second-order models are the predominant models used in investigating isothermal and kinetic adsorption and also evaluates the research gap on zeolite through scientometric analysis. The prospective efficacy of zeolite materials in future wastewater treatment may be assessed by a comparative analysis of their capacity to adsorb toxic inorganic and organic contaminates from wastewater, with other adsorbents.

Associations between antimony exposure and glycated hemoglobin levels in adolescents aged 12-19 years: results from the NHANES 2013-2016

Objective

This study aimed to investigate the association between antimony (Sb) exposure and glycated hemoglobin (HbA1c) levels in adolescents.

Methods

A cross-sectional study of 751 adolescents aged 12-19 years was conducted via the National Health and Nutrition Examination Survey (NHANES, 2013-2016). Survey-weighted linear regression and restricted cubic spline (RCS) analyses were applied to evaluate the relationship of urinary Sb exposure with HbA1c.

Results

A significant relationship was observed between urinary Sb concentrations and HbA1c levels (percent change: 0.93; 95% CI: 0.42, 1.45) after full adjustment. After converting urinary Sb levels to a categorical variable by tertiles (T1-T3), the highest quantile was associated with a significant increase in HbA1c (percent change: 1.45; 95% CI: 0.38, 2.53) compared to T1. The RCS models showed a monotonically increasing relationship of urinary Sb with HbA1c. Subgroup analyses revealed a sex-specific relationship between urinary Sb exposure and HbA1c with a significant positive association in males and a non-significant positive association in females. Sensitivity analyses further confirmed the relationship between urinary Sb and HbA1c, even after excluding participants who were overweight or obese (percent change: 1.58%, 95% CI: 0.88, 2.28) and those with serum cotinine levels ≥ 1 ng/mL (percent change: 1.14%, 95% CI: 0.49, 1.80).

Conclusion

Our findings indicated that increased Sb exposure may correlate with higher HbA1c levels, especially in male adolescents. More studies are needed to further explore and validate the potential mechanisms.

Comparative Remediation of Arsenic and Antimony Co-Contaminated Soil by Iron- and Manganese-Modified Activated Carbon and Biochar

At present, soil contaminated with arsenic (As) and antimony (Sb) is escalating at an alarming rate, which is harmful to human health. In this study, Fe- and Mn-modified activated carbon (AC) and biochar (BC) were prepared and compared for the remediation of As- and Sb-contaminated soil. The effects on the speciation of As and Sb, soil pH, organic matter (SOM), and enzyme activity with various dosages and remediation times were investigated. The results showed that on the whole, the best stabilization effect of As and Sb was achieved with 3% FeMnBC. Furthermore, with increases in time and dosage, the immobilization effect on As and Sb was more significant. Fe/Mn-modified AC and BC enhanced soil pH, with 3% MnAC being particularly effective; 3% AC and 3% FeMnAC demonstrated the most pronounced enhancement in SOM. The modified carbon materials exhibited a dramatic increase in enzymatic activity. In particular, urease activity showed an increasing trend, and catalase activity first decreased and then increased over 30 days. Among the treatments, 3% MnAC showed the most significant enhancements in catalase and urease activities, whereas 1% FeMnBC had the most pronounced effect on increasing sucrase activity. This study provides theoretical support for the remediation of soil co-contaminated with As and Sb by Fe/Mn-modified AC and BC.

Antimony sorption to schwertmannite in acid sulfate environments

Schwertmannite is a poorly-crystalline Fe(III) oxyhydroxysulfate mineral that may control Sb(V) mobility in acid sulfate environments, including acid mine drainage and acid sulfate soils. However, the mechanisms that govern uptake of aqueous Sb(V) by schwertmannite in such environments are poorly understood. To address this issue, we examined Sb(V) sorption to schwertmannite across a range of environmentally-relevant Sb(V) loadings at pH 3 in sulfate-rich solutions. Antimony K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy revealed that Sb(V) sorption (at all loadings) involved edge and double-corner sharing linkages between SbVO6 and FeIIIO6 octahedra. The coordination numbers for these linkages indicate that sorption occurred by Sb(V) incorporation into the schwertmannite structure via heterovalent Sb(V)-for-Fe(III) substitution. As such, Sb(V) sorption to schwertmannite was not limited by the abundance of surface complexation sites and was strongly resistant to desorption when exposed to 0.1 M PO43-. Sorption of Sb(V) also conferred increased stability to schwertmannite, based on changes in the schwertmannite dissolution rate during extraction with an acidic ammonium oxalate solution. This study provides new insights into Sb(V) sorption to schwertmannite in acid sulfate environments, and highlights the role that schwertmannite can play in immobilizing Sb(V) within its crystal structure.

A Sb(III)-specific efflux transporter from Ensifer adhaerens E-60

Antimony is pervasive environmental toxic substance, and numerous genes encoding mechanisms to resist, transform and extrude the toxic metalloid antimony have been discovered in various microorganisms. Here we identified a major facilitator superfamily (MFS) transporter, AntB, on the chromosome of the arsenite-oxidizing bacterium Ensifer adhaerens E-60 that confers resistance to Sb(III) and Sb(V). The antB gene is adjacent to gene encoding a LysR family transcriptional regulator termed LysRars, which is an As(III)/Sb(III)-responsive transcriptional repressor that is predicted to control expression of antB. Similar antB and lysRars genes are found in related arsenic-resistant bacteria, especially strains of Ensifer adhaerens, and the lysRars gene adjacent to antB encodes a member of a divergent subgroup of putative LysR-type regulators. Closely related AntB and LysRars orthologs contain three conserved cysteine residues, which are Cys17, Cys99, and Cys350 in AntB and Cys81, Cys289 and Cys294 in LysRars, respectively. Expression of antB is induced by As(III), Sb(III), Sb(V) and Rox(III) (4-hydroxy-3-nitrophenyl arsenite). Heterologous expression of antB in E. coli AW3110 (Δars) conferred resistance to Sb(III) and Sb(V) and reduced the intracellular concentration of Sb(III). The discovery of the Sb(III) efflux transporter AntB enriches our knowledge of the role of the efflux transporter in the antimony biogeochemical cycle.

Assessment of contamination, mobility and application of selected technology-critical elements as indicators of anthropogenic pollution of bottom sediments

The study investigates the potential of technology-critical elements (TCEs) in the bottom sediments of the Biała Przemsza River as indicators of anthropogenic activities. The mass fractions of TCEs: Ge, Ga, In, Tl, Sb and Te (and other elements) in the sediment were analysed by inductively coupled plasma mass spectrometry with the maximum mass fractions: 2.46, 25.6, 0.528, 27.7, 12.5 and 0.293 mg/kg, respectively. Distribution and identification of TCE sources were supported by statistical analysis (principal component analysis coupled with varimax rotation and hierarchical cluster analysis). Assessments of TCE contamination using the geoaccumulation index, pollution index, contamination factor, enrichment factor and the antimony-to-arsenic ratio highlighted the high contamination of bottom sediments by Sb, Ga, Tl, Cd, As, Zn, Pb and moderate contamination by Co, In and V. Distinct behaviour patterns were observed among TCEs, revealing Sb and Tl as potential indicators of Zn-Pb ore mining activities. Co, V, Ge and, to a lesser extent, Te emerged as promising indicators of coal and coal fly ash effluents. Sequential chemical extraction of TCEs showed that Sb, In and Tl had the highest mobility from sediments. The Risk Assessment Code calculations suggest, that in the Biała Przemsza River bottom sediments, there is an average risk of contamination by As, Tl and Mn. Soluble forms of Tl, Ge, Sb, Te and In were identified in descending order, indicating their bioavailability.

Metal(loid)s in urban soil from historical municipal solid waste landfill: Geochemistry, source apportionment, bioaccessibility testing and human health risks

Landfills, especially those poorly managed, can negatively affect the environment and human beings through chemical contamination of soils and waters. This study investigates the soils of a historical municipal solid waste (MSW) landfill situated in the heart of a residential zone in the capital of Slovakia, Bratislava, with an emphasis on metal (loid) contamination and its consequences. Regardless of the depth, many of the soils exhibited high metal (loid) concentrations, mainly Cd, Cu, Pb, Sb, Sn and Zn (up to 24, 2620, 2420, 134, 811 and 6220 mg/kg, respectively), classifying them as extremely contaminated based on the geo-accumulation index (Igeo >5). The stable lead isotopic ratios of the landfill topsoil varied widely (1.1679-1.2074 for 206Pb/207Pb and 2.0573-2.1111 for 208Pb/206Pb) and indicated that Pb contained a natural component and an anthropogenic component, likely municipal solid waste incineration (MSWI) ash and construction waste. Oral bioaccessibility of metal (loid)s in the topsoil was variable with Cd (73.2-106%) and Fe (0.98-2.10%) being the most and least bioaccessible, respectively. The variation of metal (loid) bioaccessibility among the soils could be explained by differences in their geochemical fractionation as shown by positive correlations of bioaccessibility values with the first two fractions of BCR (Community Bureau of Reference) sequential extraction for As, Cd, Mn, Ni, Pb, Sn and Zn. The results of geochemical fractionation coupled with the mineralogical characterisation of topsoil showed that the reservoir of bioaccessible metal (loid)s was calcite and Fe (hydr)oxides. Based on aqua regia metal (loid) concentrations, a non-carcinogenic risk was demonstrated for children (HI = 1.59) but no risk taking into account their bioaccessible concentrations (HI = 0.65). This study emphasises the need for detailed research of the geochemistry of wastes deposited in urban soils to assess the potentially hazardous sources and determine the actual bioaccessibility and human health risks of the accumulated metal (loid)s.

Managing antimony pollution: Insights into Soil-Plant system dynamics and remediation Strategies

Researchers are increasingly concerned about antimony (Sb) in ecosystems and the environment. Sb primarily enters the environment through anthropogenic (urbanization, industries, coal mining, cars, and biosolid wastes) and geological (natural and chemical weathering of parent material, leaching, and wet deposition) processes. Sb is a hazardous metal that can potentially harm human health. However, no comprehensive information is available on its sources, how it behaves in soil, and its bioaccumulation. Thus, this study reviews more than 160 peer-reviewed studies examining Sb's origins, geochemical distribution and speciation in soil, biogeochemical mechanisms regulating Sb mobilization, bioavailability, and plant phytotoxicity. In addition, Sb exposure effects plant physio-morphological and biochemical attributes were investigated. The toxicity of Sb has a pronounced impact on various aspects of plant life, including a reduction in seed germination and impeding plant growth and development, resulting from restricted essential nutrient uptake, oxidative damages, disruption of photosynthetic system, and amino acid and protein synthesis. Various widely employed methods for Sb remediation, such as organic manure and compost, coal fly ash, biochar, phytoremediation, microbial-based bioremediation, micronutrients, clay minerals, and nanoremediation, are reviewed with a critical assessment of their effectiveness, cost-efficiency, and suitability for use in agricultural soils. This review shows how plants deal with Sb stress, providing insights into lowering Sb levels in the environment and lessening risks to ecosystems and human health along the food chain. Examining different methods like bioaccumulation, bio-sorption, electrostatic attraction, and complexation actively works to reduce toxicity in contaminated agricultural soil caused by Sb. In the end, the exploration of recent advancements in genetics and molecular biology techniques are highlighted, which offers valuable insights into combating Sb toxicity. In conclusion, the findings of this comprehensive review should help develop innovative and useful strategies for minimizing Sb absorption and contamination and thus successfully managing Sb-polluted soil and plants to reduce environmental and public health risks.

Green and blue infrastructure as model system for emissions of technology-critical elements

Over the recent decades, technological advancements have led to a rise in the use of so-called technology-critical elements (TCEs). Environmental monitoring of TCEs forms the base to assess whether this leads to increased anthropogenic release and to public health implications. This study employs an exploratory approach to investigate the distribution of the TCEs Li, Be, V, Ga, Ge, Nb, Sb, Te, Ta, Tl, Bi and the REYs (rare-earth elements including yttrium) in urban aerosol in the city of Vienna, Austria. Leaf samples (n = 292) from 8 plant species and two green facades and water samples (n = 18) from the Wienfluss river were examined using inductively coupled plasma tandem mass spectrometry (ICP-MS/MS). Surface dust contributions were assessed by washing one replicate of each leaf sample and analysing the washing water (n = 146). The impacts of sampling month, plant species and storey level on elemental distribution were assessed by statistical tools and generative deep neural network modelling. Higher TCE levels, including Li, V, Ga, Ge, Tl, Bi, and the REYs, were found in the winter months, likely due to the use of de-icing materials and fossil fuel combustion. A. millefolium and S. heufleriana displayed the highest levels of Li and Ge, respectively. In addition, increased elemental accumulation at lower storeys was observed, including Be, Sb, Bi and the REYs, indicating greater atmospheric dust deposition and recirculation closer to ground level. The results suggest a broad association of TCE levels with urban dust. This study enhances the current understanding of TCE distribution in urban settings and underscores the importance of their inclusion in pollution monitoring. It highlights the complex interplay of human activities, urban infrastructure, and environmental factors, offering valuable insights for managing urban environmental health risks and underlining the need for comprehensive urban ecosystem studies.

Application of soil magnetometry and geochemical methods to investigate soil contamination with antimony

The aim of the study was an assessment of the pollution level and identification of the antimony sources in soils in areas subjected to industrial anthropopressure from: transport, metallurgy and electrical waste recycling. The combination of soil magnetometry, chemical analyzes using atomic spectrometry (ICP-OES and ICP-MS), Sb fractionation analysis, statistical analysis (Pearson's correlation matrix, factor analysis) as well as Geoaccumulation Index, Pollution Load Index, and Sb/As factor allowed not only the assessment of soil contamination degree, but also comprehensive identification of different Sb sources. The results indicate that the soil in the vicinity of the studied objects was characterized by high values of magnetic susceptibility and thus, high contents of potentially toxic elements. The most polluted area was in the vicinity of electrical waste processing plants. Research has shown that the impact of road traffic and wearing off brake blocks, i.e. traffic anthropopression in general, has little effect on the surrounding soil in terms of antimony content. Large amounts of Pb, Zn, As and Cd were found in the soil collected in the vicinity of the heap after the processing of zinc-lead ores, the average antimony (11.31 mg kg-1) content was lower in the vicinity of the heap than in the area around the electrical and electronic waste processing plant, but still very high. Antimony in the studied soils was demobilized and associated mainly with the residual fraction.

Effective immobilization and biosafety assessment of antimony in soil with zeolite-supported nanoscale zero-valent iron

Antimony (Sb) contamination in certain areas caused by activities such as antimony mining and smelting poses significant risks to human health and ecosystems. In this study, a stable composite material consisting of natural zeolite-supported nanoscale zero-valent iron (Z-ZVI) was successfully prepared. The immobilization effect of Z-ZVI on Sb in contaminated soil was investigated. Experimental results showed that Z-ZVI exhibited superior performance compared to pure nano zero-valent iron (nZVI) in terms of stability, with a lower zeta potential (-25.16 mV) at a pH of 7 and a higher specific surface area (54.54 m2/g). It can be easily applied and dispersed in contaminated soils. Additionally, Z-ZVI demonstrated a more abundant porous structure. After 60 days of treatment with 3% Z-ZVI, the leaching concentration of Sb in the contaminated soil decreased from 1.32 mg/L to 0.31 mg/L (a reduction of 76%), and the concentration of available Sb species decreased from 19.84 mg/kg to 0.71 mg/kg, achieving a fixation efficiency of up to 90%. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis confirmed the effective immobilization of Sb in the soil through reduction of antimonate to antimonite, precipitation, and adsorption processes facilitated by Z-ZVI. Moreover, the addition of Z-ZVI effectively reduced the bioavailability of Sb in the contaminated soil, thereby mitigating its toxicity to earthworms. In conclusion, Z-ZVI can be utilized as a promising material for the safe remediation and antimony and other heavy metal-contaminated soils.

Efficient removal of Sb(III) from wastewater using selenium nanoparticles synthesized by Psidium guajava plant extract

Antimony (Sb) pollution in aquatic ecosystems has emerged as a critical environmental issue on a global scale, emphasizing the urgent need for cost-effective and user-friendly technologies to remove Sb compounds from water sources. In this study, a novel adsorbent, selenium nanoparticles (SeNPs), was synthesized using the aqueous extract of Psidium guajava L. leaves (AEP) for the purpose of eliminating Sb(III) from aqueous solutions. The biosynthesized SeNPs was characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray fluorescence spectrometer (XRF), Fourier Transform-Infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis techniques. Additionally, the removal efficiency of the SeNPs for Sb(III) was systematic investigated under the effects of SeNPs dose, temperature, pH and re-usability. The results of this study showed that the adsorption data fitted well into pseudo-second order model, while the Sips modeling demonstrated a high adsorption capacity (62.7 mg/g) of SeNPs for Sb(III) ions at 303.15 K from aqueous solution. The exothermic enthalpy change of - 22.59 kJ/mol and negative Gibbs free energy change assured the viability of the adsorption process under the considered temperature conditions. Surface functional groups on SeNPs like carboxyl, amide, hydroxyl, carbonyl, and methylene significantly facilitate the adsorption processes. Furthermore, the removal efficiencies of Sb in the two actual Sb mine wastewater samples were remarkably high, achieving nearly to 100% with 1.5 g/L SeNPs within 48 h. This outcome underscores the potential of SeNPs as a highly promising solution for efficiently remediating Sb from aquatic environments, owing to their cost-effectiveness, ease of regeneration, and rapid uptake capabilities.

Removal of Aqueous Antimony and Arsenic by Iron-Loaded Coal Gasification Slag Composite

The adsorption of Sb(V) and As(V) onto iron-loaded gasification slag composite material (Fe-GFS), as well as the possible mechanisms, was investigated. Batch experiments showed that in a single system, Fe-GFS sorbed As(V) to a greater extent than Sb(V) with the maximum adsorption capacity (pH 3.0) of 34.99 mg/g (0.47 mmol/g), while that of Sb(V) was 27.61 mg/g (0.23 mmol/g). In the composite system, the presence of low concentrations of Sb(V) reduced the adsorption efficiency of Fe-GFS for As(V), while the presence of high concentrations of Sb(V) actually promoted the adsorption of As(V). The presence of As(V) consistently inhibited the adsorption of Sb(V) by Fe-GFS. Compared to Fe-GFS, new peaks appeared in the FTIR spectra after adsorption, indicating the presence of Sb-O and As-O bonds on the surface after adsorption. XPS results showed that the adsorption of As(V) and Sb(V) led to a decrease in Fe-OH bonds, with a more significant decrease in Fe-OH bonds observed after the adsorption of As(V), indicating a stronger affinity of Fe-GFS for As(V) compared to Sb(V). Our results suggest that Fe-GFS is an efficient adsorbent with great potential for applications in water containing As(V) and Sb(V).

Optimizing Antimony Speciation Analysis via Frontal Chromatography-ICP-MS to Explore the Release of PET Additives

Antimony (Sb) contamination poses significant environmental and health concerns due to its toxic nature and widespread presence, largely from anthropogenic activities. This study addresses the urgent need for an accurate speciation analysis of Sb, particularly in water sources, emphasizing its migration from polyethylene terephthalate (PET) plastic materials. Current methodologies primarily focus on total Sb content, leaving a critical knowledge gap for its speciation. Here, we present a novel analytical approach utilizing frontal chromatography coupled with inductively coupled plasma mass spectrometry (FC-ICP-MS) for the rapid speciation analysis of Sb(III) and Sb(V) in water. Systematic optimization of the FC-ICP-MS method was achieved through multivariate data analysis, resulting in a remarkably short analysis time of 150 s with a limit of detection below 1 ng kg-1. The optimized method was then applied to characterize PET leaching, revealing a marked effect of the plastic aging and manufacturing process not only on the total amount of Sb released but also on the nature of leached Sb species. This evidence demonstrates the effectiveness of the FC-ICP-MS approach in addressing such an environmental concern, benchmarking a new standard for Sb speciation analysis in consideration of its simplicity, cost effectiveness, greenness, and broad applicability in environmental and health monitoring.

Arsenic and antimony desorption in water treatment processes: Scaling up challenges with emerging adsorbents

The metalloids arsenic (As) and antimony (Sb) belong to the pnictogen group of the periodic table; they share many characteristics, including their toxic and carcinogenic properties; and rank as high-priority pollutants in the United States and the European Union. Adsorption is one of the most effective techniques for removing both elements and desorption, for further reuse, is a part of the process to make adsorption more sustainable and feasible. This review presents the current state of knowledge on arsenic and antimony desorption from exhausted adsorbents previously used in water treatment, that has been reported in the literature. The application of different types of eluents to desorb As and Sb and their desorption performance are described. The regeneration of saturated adsorbents and adsorbate recovery techniques are outlined, including the fate of spent media and possible alternatives for waste disposal of exhausted materials. Future research directions are discussed, as well as current issues including the lack of environmental impact analysis of emerging adsorbents.

Insights into the biogeochemical transformation, environmental impacts and biochar-based soil decontamination of antimony

Every year, a significant amount of antimony (Sb) enters the environment from natural and anthropogenic sources like mining, smelting, industrial operations, ore processing, vehicle emissions, shooting activities, and coal power plants. Humans, plants, animals, and aquatic life are heavily exposed to hazardous Sb or antimonide by either direct consumption or indirect exposure to Sb in the environment. This review summarizes the current knowledge about Sb global occurrence, its fate, distribution, speciation, associated health hazards, and advanced biochar composites studies used for the remediation of soil contaminated with Sb to lessen Sb bioavailability and toxicity in soil. Anionic metal(loid) like Sb in the soil is significantly immobilized by pristine biochar and its composites, reducing their bioavailability. However, a comprehensive review of the impacts of biochar-based composites on soil Sb remediation is needed. Therefore, the current review focuses on (1) the fundamental aspects of Sb global occurrence, global soil Sb contamination, its transformation in soil, and associated health hazards, (2) the role of different biochar-based composites in the immobilization of Sb from soil to increase biochar applicability toward Sb decontamination. The review aids in developing advanced, efficient, and effective engineered biochar composites for Sb remediation by evaluating novel materials and techniques and through sustainable management of Sb-contaminated soil, ultimately reducing its environmental and health risks.

Factors driving antimony accumulation in soil-pakchoi and wheat agroecosystems: Insights and predictive models

The accumulation of antimony (Sb) in plants and its potential effects on human health are of increasing concern. Nevertheless, only a few countries or regions have established soil Sb thresholds for agricultural purposes, and soil properties have not been taken into account. This study investigated the accumulation of Sb in the edible parts of pakchoi and wheat grain by adding exogenous Sb to 21 soils with varying properties. The results revealed a positive correlation between bioavailable Sb (Sbava, extracted by 0.1 M K2HPO4) in soil and Sb in the edible parts of pakchoi (R2 = 0.77, p < 0.05) and wheat grain (R2 = 0.54, p < 0.05). Both machine learning and traditional multiple regression analysis indicated Sbava was the most critical feature and the main soil properties that contributed to Sb uptake by pakchoi and wheat were CaCO3 and clay, respectively. The advisory food limits for Sb in pakchoi and wheat were estimated based on health risk assessment, and used to derive soil thresholds for safe pakchoi and wheat production based on Sbtot and Sbava, respectively. These findings hold potential for predicting Sb uptake by crops with different soil properties and informing safe production management strategies.

Almond shell-derived biochar decreased toxic metals bioavailability and uptake by tomato and enhanced the antioxidant system and microbial community

The effectiveness of almond shell-derived biochar (ASB) in immobilizing soil heavy metals (HMs) and its impact on soil microbial activity and diversity have not been sufficiently studied. Hence, a pot study was carried out to investigate the effectiveness of ASB addition at 2, 4, and 6 % (w/w) on soil biochemical characteristics and the bioavailability of Cd, Cu, Pb, and Zn to tomato (Solanum lycopersicum L.) plants, as compared to the control (contaminated soil without ASB addition). The addition of ASB promoted plant growth (up to two-fold) and restored the damage to the ultrastructure of chloroplast organelles. In addition, ASB mitigated the adverse effects of HMs toxicity by decreasing oxidative damage, regulating the antioxidant system, improving soil physicochemical properties, and enhancing enzymatic activities. At the phylum level, ASB addition enhanced the relative abundance of Actinobacteriota, Acidobacteriota, and Firmicutes while decreasing the relative abundance of Proteobacteria and Bacteroidota. Furthermore, ASB application increased the relative abundance of several fungal taxa (Ascomycota and Mortierellomycota) while reducing the relative abundance of Basidiomycota in the soil. The ASB-induced improvement in soil properties, microbial community, and diversity led to a significant decrease in the DTPA-extractable HMs down to 41.0 %, 51.0 %, 52.0 %, and 35.0 % for Cd, Cu, Pb, and Zn, respectively, as compared to the control. The highest doses of ASB (ASB6) significantly reduced the metals content by 26.0 % for Cd, 78.0 % for Cu, 38.0 % for Pb, and 20.0 % for Zn in the roots, and 72.0 % for Cd, 67.0 % for Cu, 46.0 % for Pb, and 35.0 % for Zn in the shoots, as compared to the control. The structural equation model predicts that soil pH and organic matter are driving factors in reducing the availability and uptake of HMs. ASB could be used as a sustainable trial for remediation of HMs polluted soils and reducing metal content in edible plants.