Sb Content Research Articles

Impurity Behavior in Cast Copper Anodes: Implications for Electrorefining in a Circular Economy

The behavior of impurities in cast copper was investigated to simulate production with increased utilization of secondary sources within the framework of a circular economy. The incorporation of impurities, particularly Ni, Sn, and Sb, from recycled Cu may significantly impact the electrorefining process. In this study, commercial anodes were doped with Ni, Sn, and Sb concentrations of 2500–6500 g/t, 300–900 g/t, and 450–950 g/t, respectively. Anode concentrations of Pb and Bi were maintained at 1000 g/t and 350 g/t, respectively. As concentrations were examined at two levels, 860 or 1700 g/t, depending on the commercial anode used to create the doped samples. Electron microscopy with microprobe analysis revealed that the commercial anodes contained three predominant phases: Cu2O, (Cu,Ag)2(Se,Te), and a complex oxide phase of Cu, Pb, As, Sb, and/or Bi. Ni, the main impurity, primarily accumulated within the Cu grains, while Sn and Sb tended to form oxidized inclusions. The distribution of Ni in Cu grains was ca. 20% lower in the anodes doped at higher Ni concentrations due to the formation of nickel-bearing inclusions, such as Kupferglimmer and NiO. The doped anodes showed lower quantities of Cu2O inclusions than the commercial anodes due to the preferential formation of oxides with other impurities, including SnO2. These findings highlight potential challenges for Cu electrorefining in a circular economy, as Ni, Sb, and Sn may impact the deportment of these impurities to slimes or electrolyte and may cause copper depletion in the refining electrolyte.

Assessment of Ecological Recovery Potential of Various Plants in Soil Contaminated by Multiple Metal(loid)s at Various Sites near XiKuangShan Mine

Soil metal(loid) pollution is a threat to ecological and environmental safety. The vegetation recovery in mining areas is of great significance for protecting soil resources. In this study, (1) we first gathered four types of soils to analyse their contamination degree, including tailings mud (TM), wasteland soil (TS) very near TM, as well as non-rhizosphere soils of pepper (PF) and maize (MF) in a farmland downstream from the TM (about 5 km). Geo-accumulation and potential ecological risk indices indicated that the soil samples were mainly polluted by antimony (Sb), arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), and copper (Cu) to different degrees. Leachates of TM resulted in increased Sb, As, and Cd accumulation in TS. (2) Then, we sampled six local plants growing in the TS to assess the possibilities of using these plants as recovery vegetation in TS, of which Persicaria maackiana (Regel) Nakai ex T. Mori absorbed relatively high Sb concentrations in the leaves and roots. (3) After that, we collected rhizosphere soil and tissue samples from eight crops on the above farmland to assess their capacities as recovering vegetation of contaminated farmland soil, of which the fruits of maize accumulated the lowest concentrations of most monitored metal(loid)s (except for Pb). Further, we compared the differences in the bacterial community structure of MF, PF, TM, and TS to assess capacities of cultivating pepper and maize to improve soil microbial community structure. The MF displayed the best characteristics regarding the following attributes: (1) the highest concentrations of OMs and total P; (2) the highest OTU numbers and diversity of bacteria; and (3) the lowest abundance of bacteria with potentially pathogenic and stress-tolerant phenotypes.

Concentrations and origins of ultrafine particles at a major European harbor.

The maritime transport sector poses significant air quality concerns, particularly in nearby cities. Ultrafine particles (UFP, diameter<100nm) are of particular concern due to their potential health impacts. This study measured particle number concentrations (PNC), size distributions (PNSD), and other pollutants including particulate matter (PM), nitrogen oxides (NOX), black carbon (BC), sulfur dioxide (SO2) and ozone (O3), organic markers and trace elements at a major European harbor and an urban background (UB) location. The average PNC at the harbor was 1.8-fold higher than at the UB, with particularly marked differences in the Aitken mode (2.4-fold higher). NOx levels were 10.5-fold higher at the harbor, and NO2, NOX and BC concentrations were 2.0 to 2.9 times greater compared to the UB site. SO2 concentrations were also 1.7-fold higher at the harbor. Two distinct types of PNC peaks were observed: daytime peaks with high Aitken mode particles likely linked to transit ship emissions, and late afternoon/nighttime peaks with higher nucleation mode particles likely linked to thermal power plant emissions, docked cruise ships, and vehicular traffic related to ferry boarding. Source apportionment of PNC-PNSD through Positive Matrix Factorization (PMF) identified four key contributors to PNC at the harbor: Regional recirculation (9%, modes: 100nm and 35nm), Nucleation (30%, mode: 18nm), Coastal background (22%, mode: 75nm), and Ship transit (33%, mode, 35nm). Concentrations of Ti, V, Cr, Ni, Cu, Zn, As, Sb, Pb and Na in the quasi-UFP range were more than twice at the harbor compared to the UB. This study provides insights into UFP concentrations and their sources within a major touristic and commercial harbor, highlighting the complexity of identifying specific contributions from various UFP emission sources in large harbors.

Associations of Exposure to 56 Serum Trace Elements with the Prevalence and Severity of Acute Myocardial Infarction: Omics, Mixture, and Mediation Analysis.

Several studies have reported associations between specific heavy metals and essential trace elements and acute myocardial infarction (AMI). However, there is limited understanding of the relationships between trace elements and AMI in real-life co-exposure scenarios, where multiple elements may interact simultaneously. This cross-sectional study measured serum levels of 56 trace elements using inductively coupled plasma mass spectrometry. We identified individual trace elements linked to AMI using four feature selection methods and evaluated their associations with AMI prevalence and severity through multiple-element logistic regression. Restricted cubic spline analysis was employed to examine non-linear associations. Additionally, we explored the associations between trace element mixtures and AMI prevalence and severity using Bayesian kernel machine regression (BKMR) and element risk score (ERS). Finally, we investigated the potential mechanisms linking trace element exposure to AMI. We detected stable positive associations and linear relationships between Cu and Rb and AMI prevalence and severity. Furthermore, lower Fe concentrations were associated with higher AMI prevalence, while higher Sb concentrations were linked to greater AMI severity. Both BKMR and ERS models indicated positive associations between trace element mixtures and AMI prevalence and severity. Mediation analysis suggested that high-sensitivity C-reactive protein partially mediated the associations between trace elements and AMI prevalence and severity. We provide the first epidemiological evidence of the associations between serum trace element mixtures and AMI prevalence and severity. Under conditions of trace element co-exposure, Cu, Rb, Fe, and Sb were closely associated with AMI. Additionally, our results indicate that hsCRP (inflammation) may be a potential mechanism linking trace elements to AMI.

Extracellular enzymes as reliable indicators of long-term antimony contamination.

Antimony (Sb) contamination in soil has become a growing concern due to its toxic effects on ecological soil functions. Soil enzymes, which are effective biological indicators, play a crucial role in assessing the ecological impact of heavy metals in soil. However, the effects of Sb on soil enzyme activity, particularly during the ageing process, remain poorly understood. This study examines the ageing process of Sb in soil and its biological toxicity on three key soil enzyme activities (arylsulfatase, urease, phosphatase) at different enzyme pool levels (total, intracellular and extracellular). Our findings reveal that the ageing of exogenous Sb in soil follows a heterogeneous dispersion process, with the Sb ageing rate constant (|b|) in acidic soil (S1, red soil, pH4.90) being 1.21 to 1.90 times higher than in alkaline soil (S2, gray desert soil, pH8.12). This suggests that Sb stabilizes more rapidly in acidic conditions. Regarding Sb effects on soil enzymes, extracellular urease activity and the total enzyme activity index (TEI) of extracellular enzymes were particularly sensitive to Sb stress. Over the course of the ageing period, extracellular urease activity decreased by 23.46-57.85% in both soils under Sb stress at 7000mg·kg-1. The inhibition of TEI by Sb ranged from 29.08 to 42.47% in S1 soil, and from 12.47 to 20.65% in S2 soil. Ecological dose (ED10) values indicated that Sb concentrations of 24.86-184.00mg·kg-1 caused a 10% reduction in extracellular enzyme TEI, whereas higher Sb concentrations (29.63-1791.86mg·kg-1) were needed to inhibit 10% of extracellular urease activity. Overall, TEI of extracellular enzymes emerges as a more sensitive and reliable indicator of long-term Sb contamination. This study provides essential insights for monitoring Sb pollution and provides a basis for establishing a soil Sb pollution assessment and early-warning system.

ELECTROCHEMICAL CORROSION EVALUATION OF SnSb ELECTRODEPOSITED COATINGS

SnxSb(1−x) coatings were electrodeposited from 1ChCl:2EG on copper. The corrosion resistance of the electrodeposits was evaluated in 0.1 mol dm-3 of NaCl. The characterization was performed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Voltammetric profiles showed that the electrodeposition potential shifted towards less positive values with increasing Sb3+ concentration. SEM images revealed that the coatings exhibited grains and clusters. EDS analyses showed that the Sb content increased with the Sb3+ concentration. XRD results indicated the formation of the SbSn phases such as Cu2Sb, Cu6Sn5, and Cu6(Sn,Sb)5. The potentiodynamic polarization (PP) curves showed that Sn and Sn77Sb23 presented a passive potential region, while Sn37Sb63 had an active dissolution in the electrolyte. Immersion tests were performed for 24 h and XRD results revealed Cu, Sn, SnO, SbSn and Sb2O4 phases. Considering 48 h, Cu, CuSn, SnO2 and SnSb phases were identified. The polarization resistance values of 4.60, 14.69 and 1.81 kΩ cm2 were achieved for Sn, Sn77Sb23, and Sn37Sb63, respectively. The EIS results suggested that adding Sb3+ improves corrosion resistance for SnSb samples with higher Sn content. For Sn77Sb23, the charge transfer resistance was 10.5 kΩ cm2, for Sn and Sn37Sb63 1.15 and 1.46 kΩ cm2, respectively.

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.

Source and Ecological Risk Assessment of Potentially Toxic Metals in Urban Riverine Sediments Using Multivariate Analytical and Statistical Tools

Multivariate and statistical tool advancements help to assess potential pollution threats, their geochemical distribution, and the competition between natural and anthropogenic influences, particularly on sediment contamination with potentially toxic metals (PTMs). For this, riverine sediments from 25 locations along urban banksides of the River Ravi, Pakistan, were collected and analyzed to explore the distribution, pollution, ecological, and toxicity risk indices of PTMs like Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Sn, Sr, V, and Zn using Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES) technique. Additionally, techniques such as X-ray Diffraction (XRD) and Scanning Electron Microscopy–Energy Dispersive X-ray Spectroscopy (SEM-EDS) were employed to investigate the mineralogical and morphological aspects. The results indicated that mean concentrations (mg kg−1) of Cd (2.37), Cr (128), Hg (16.6), Pb (26.6), and Sb (2.44) were significantly higher than reference values given for upper continental crust (UCC) and world soil average (WSA), posing potential threats. Furthermore, the geochemical pollution indices showed that sediments were moderately polluted with Cd (Igeo = 2.37, EF = 12.1, and CF = 7.89) and extremely polluted with Hg (Igeo = 4.54, EF = 63.2, and CF = 41.41). Ecological and toxicity risks were calculated to be extremely high, using respective models, predominantly due to Hg (Eri = 1656 and ITRI = 91.6). SEM-EDS illustrated the small extent of anthropogenic particles having predominant concentrations of Zn, Fe, Pb, and Sr. Multivariate statistical analyses revealed significant associations between the concentrations of PTMs and the sampling locations, highlighting the anthropogenic contributions linked to local land-use characteristics. The present study concludes that River Ravi sediments exhibit moderate levels of Cd and extreme pollution by Hg, both of which contribute highly to extreme ecological and toxicity risks, influenced by both natural and anthropogenic contributions.

Influence of Sb content on carrier transport and thermoelectric properties of flexible Bi–Sb films

In this study, the Bi–Sb films with different Sb content on silicon and polyimide (PI) substrates were successfully fabricated via high vacuum magnetron sputtering and the carrier transport and thermoelectric properties were studied. As the Sb content increased, the carrier concentration, electrical conductivity, Seebeck coefficient, and power factor of deposited Bi–Sb films initially increased and then decreased at room temperature. The maximum Seebeck coefficient and power factor reached −108.90 μV K−1 and 0.133mW m−1 K−2 for the Bi84Sb16 film at room temperature. The electrical conductivity, Seebeck coefficient, and power factor of deposited Bi–Sb films increased with increasing energy gap. Whether bending toward or bending back toward, the relative electrical conductivity of the films decreased with increasing bending angle. When the bending angle was less than 90°, the electrical conductivity of the films decreased very little. However, the electrical conductivity of the films exhibited an obvious reduction when the bending angle exceeded 90°. The relative electrical conductivity of the deposited films under bending toward and bending back toward decreased by 4% and 8% under 180° bending angle, respectively. Compared with bending toward, the electrical conductivity of the films bending back toward (tensile) decreases even more at the same bending angle. The electrical conductivity of the films bending toward changed little and remained 94.1% after bending 1000 times at the radius of 3 mm. The maximum power density of a flexible thermoelectric generator for Bi84Sb16 film was 0.672 and 0.8644 W m−2 at ΔT = 30 and 39 K, respectively.

Trace elements in the sediment cores of lakes on King George Island, Antarctica

Primary studies of the concentrations of rare elements in the sediments of two lakes on King George Island (Kitezh and Glubokoe) showed that their geochemistry reflects the geological features of the area. Compared to the upper part of the Earth's crust, the studied sediments are enriched in Cu, Cd, V, Tl, Mn, Ti and P. Similar patterns have been identified in the geochemistry of volcanic and sedimentary rocks of the Fildes Peninsula. Trends in REE changes generally follow their behavior in rocks, but the overall REE concentration in sediments of lakes is higher, which may be due to the presence of organic matter accumulating in sediments of water bodies. Unlike the aquatic environment, the chemical composition of sediments does not reflect the significant influence of the activities of polar stations. However, small increases in Pb and Sb concentrations in the upper sediments suggest the influence of long-range atmospheric transport of the contaminants.

Promoting the recovery of soil health in As and Sb-polluted soils: new evidence from the biochar-compost option

The role of compost and biochar in the recovery of As and Sb-polluted soils is poorly investigated, as well as the influence of their application rates on soil health and quality. In this study, we therefore investigated the effectiveness over time (2, 4, and 6 months, M) of a municipal solid waste compost (MSWC) and a biochar (BC), applied at 10 and 30% rates, and of selected mixtures (MIX; applied at 10 and 30% total rates, 1:1 ratio of MSWC and BC), on labile As and Sb in a polluted soil from an abandoned Sb mine (Djebel Hamimat, Algeria). At the same timepoints, the amendment impact on soil chemistry was also monitored, while the activity and diversity of the resident microbial communities were investigated at 6 M. After 6 months, MSWC, BC, and MIX applied at the higher rate significantly increased soil pH (from 7.5 up to 8.2), while MSWC and MIX increased soil EC to worrying values. The soil dissolved organic carbon content was also greatly increased by MSWC and MIX at the higher rates (up to 50-fold), while BC showed a negligible impact. All the amendments reduced the concentration of labile Sb in soil, with BC 10% being the most effective treatment (i.e., reducing labile Sb from ~ 60 to 20 mg kg−1 soil). On the contrary, only BC and MIX applied at 10% significantly reduced labile As (e.g., from ~ 12 to 4 mg kg−1 soil in the case of BC). MSWC and MIX at both rates increased up to 2000-fold soil dehydrogenase activity, while BC showed a null impact. The Biolog community level physiological profile and sequencing of the partial 16S rRNA gene showed a reduction of catabolic activity and α-diversity and a change of the community composition of bacterial populations in treated soils. Overall, MIX treatment, especially at 10%, was the most promising option for the chemical and biological recovery of As and Sb-polluted soils.

CONTAMINATION OF PET BOTTLED CARBONATED SOFT DRINKS SOLD IN NIGERIA AFTER LONG STORAGE DUE TO ANTIMONY LEACHING: RISK ASSESSMENT

This research was carried out to ascertain the rate of leaching of antimony (Sb)from PET bottled soft drinks after long storage and to calculate the health risk associated with this leaching. Six different brands of soft drinks sold in Nigeria (eleven bottles of each) were purchased from 9th mile area of Enugu State. One bottle of each brand was analysed for antimony before storage to serve as control. Five bottles of each brand were exposed to sunlight while five bottles of each brand were stored at room temperature and they were analysed for antimony concentration after 3, 6, 9, 12 and 15 weeks of storage. For sample 1, Sb concentration ranged from 0.004 to 0.010 and 0.004 to 0.011, sample 2 ranged from 0.001 to 0.006 and 0.001 to 0.010, sample 3 ranged from 0.001 to 0.008 and 0.001 to 0.014, sample 4 ranged from 0.002 to 0.007 and 0.002 to 0.010. sample 5 ranged from 0.003 to 0.006 and 0.003 to 0.011, sample 6 ranged from 0.001 to 0.006 and 0.001 to 0.010 for room temperature and sunlight exposed samples respectively. The antimony concentration on the samples were found to exceed the WHO limit of 0.006 at 15 weeks of exposure to sunlight apart from sample 2. It was observed that the cancer risk increased with increase in storage time, temperature and amount of leached antimony increases.

Characteristics of heavy metal migration from virgin PET and recycled PET plastic bottles in beverage products

Polyethylene terephthalate (PET) is one of the most commonly used packaging materials for beverages. The increased use of PET has contributed to the rise in plastic waste. Recycled PET (R-PET) is a solution to address this environmental issue. This study aims to determine the migration level of Pb, Cd, Hg, and Sb in PET bottles, evaluate the effect of plastic types (virgin PET and R-PET) and testing conditions (according to BPOM following national regulation and EU following international regulation) on the migration from heavy metals into food. Sixty test samples of virgin PET and R-PET bottles, obtained from four packaging industries in Indonesia, were analyzed for Cd, Hg, Pb, and Sb concentrations using ICP-MS. The results showed that the highest concentrations of heavy metal migration for Cd and Pb were in a virgin PET sample according to BPOM, respectively, at 28 ± 2 ng/L and 636 ± 22 ng/L. Meanwhile, the highest concentrations of Hg and Sb were in a R-PET sample according to EU, respectively, at 469 ± 91 ng/L and 5042 ± 617 ng/L. There was a significant difference in heavy metal levels between the two types of plastic (virgin PET and R-PET) and two testing conditions (BPOM and EU). However, all the obtained concentrations were below the permitted limits of national and EU regulations.

Characterizing and sourcing metal air contamination coupling concentrations and lead isotopes from moss biomonitoring in urban cemeteries

Populations are constantly exposed to airborne metals, in particular in urban areas. Despite their proven links to health issues, their origin and fate are still subject to debate. Bioindicators, by taking up and cumulating atmospheric metals over time, have been widely used to proxy environmental quality over large areas, at various time scales. Using the example of the Paris region, we investigated the potential for the Grimmia pulvinata moss species to both characterize air metal contamination and to identify its main sources. To this end, we coupled metal/metalloid (Al, As, Cd, Cr, Cu, Fe, Ni, Pb, Sb, Sr, V and Zn) concentrations and Pb isotope ratios from samples collected in cemeteries in the city and its suburbs. Metal enrichment factors ranged between 2 and 10 for As, Cr, Fe, Ni, Sr, V, between 50 and 100 for Cu, Pb and Zn and > 100 for Cd and Sb, indicating a dominant anthropogenic origin. Principal component analysis showed that 3 principal components explained 89% of the metal variations: (i) European atmospheric background, (ii) regional urban sources, and (iii) resuspension of regional soils. This was corroborated by Pb isotope ratios, whose variations were modelled by a ternary mixing that considered the same 3 emission sources. Using a MixSIAR isotope model, we reveal that the European atmospheric background contributes slightly (< ~ 5%) and that within 20 km of the city center bioindicators are mostly impacted by urban sources (contributions: 50–80%). Samples collected > 20 km show almost equal contributions of the endmembers representing urban activities and agricultural soil resuspension.

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 (1000mgkg-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.

Mechanism of antimony oxidation and adsorption using immobilized Klebsiella aerogenes HC10 in soil

Klebsiella aerogenes HC10 is one of the few strains isolated from contaminated soil that efficiently oxidizes Sb. However, the sensitivity of microorganisms to environmental conditions limits Sb-oxidizing bacteria applications in soil remediation. Immobilizing Sb-oxidizing bacteria is a promising strategy to improve colonization rates and microorganism inefficiencies and to strengthen bioremediation in Sb-contaminated soil. This study evaluated the feasibility of an immobilization approach to enhance Sb oxidation and the remediation performance of strain HC10 in soil. The results indicated that a mixed matrix of polyvinyl alcohol and sodium alginate as fixed carriers provided a porous microstructural environment conducive to HC10 colonization and proliferation. Sb(III) concentration was reduced by 9.8 mg/L. The total Sb decreased by 3.8 mg/L by immobilized HC10 after 7 d. Key metabolites involved in Sb oxidation and adsorption were significantly upregulated. In soil, immobilized HC10 removed 48.68 % and 61.74 % of water-extractable and citric acid-extractable Sb(III), respectively. Some well-crystallized (hydr)oxide Sb fractions binding to the mineral surface were transformed into the mineral lattice form, creating an inner-sphere complex that effectively immobilized Sb. Immobilized HC10 enhanced hydrogen peroxidase, urease, and sucrase activities related to soil antioxidants and nutrient cycling. Immobilized HC10 promoted the proliferation of indigenous bacteria, which emerged as the dominant bacterial community with the potential for Sb oxidation. The ars operon genes associated with Sb resistance and transport were significantly expressed in HC10 treatments, providing a crucial basis for colonization in the soil. These results highlight the potential of immobilized Sb-oxidizing bacteria for enhanced bioremediation of Sb-contaminated soil.

Long-term soil remediation using layered double hydroxides: Field evidence for simultaneous immobilization of both cations and oxyanions

Layered double hydroxides (LDHs) have great potential for immobilizing potentially toxic elements in soil. Nevertheless, their practical effectiveness under field conditions remains largely unknown. In this study, we conducted a 2.5-year field trial using pristine Mg-Al LDHs, Ca-Al LDHs, and iron (Fe)-modified LDHs to simultaneously immobilize both oxyanions (including As and Sb) and cations (including Cd and Pb) in historically contaminated soil affected by mining activities since the 1950s. The immobilization performance of LDHs was examined using various batch tests, including water and DTPA extraction, and by measuring metal(loid) concentrations in Coriandrum sativum (coriander). We found that both pristine and Fe-modified LDHs showed promising initial immobilization performance 7 days after application, achieving significant reductions in DTPA-extractable concentrations of As, Sb, Cd, and Pb by 45.6%–68.3%, 55.4%–94.2%, 11.2%–50.9%, and 62.9%–64.9%, respectively, compared to the control soil without amendment. Notably, pristine LDHs showed diminished immobilization performance in the long term, while Fe-modified LDHs exhibited long-term stability over 2.5 years. A conditional probability-based model was used to depict long-term metal(loid) leaching characteristics in LDH-amended soils. Temporal changes in metal(loid) concentrations in the aboveground edible parts (namely, stems and leaves) of coriander corroborated well with DTPA extraction results. Coriander grown in Fe-modified LDH-amended soils had much lower metal(loid) concentrations compared to those grown in pristine LDH-amended soils. As a result, reductions of 35.1%–42.2% for As, 54.4%–66.2% for Sb, 8.5%–22.8% for Cd, and 56.0%–62.7% for Pb concentrations in coriander were still observed 2.5 years after soil amendment with Fe-modified LDHs. To the best of our knowledge, this is the first field-based evidence using LDHs to simultaneously stabilize both cations and oxyanions in soil. The findings support the potential of LDHs for long-term immobilization of metal(loid)s in soil.

Concentration of Chemical Elements in the Leaves of the &lt;i&gt;Salix miyabeana&lt;/i&gt; Seemen, Growing in the Area of the Tailings Dam of the Darasun Gold Deposit

In the area of the tailings dam of the Darasun gold deposit in the Trans-Baikal Territory, the content of 47 chemical elements in the leaves of the Miabe willow (Salix miyabeana), as well as their gross content in the soil in places where plants grow, were studied to obtain information about the accumulation of elements by the plant on contaminated soils and the prospect of using Miabe willow as a phytoextractor plant. The analysis of plant and soil samples was carried out on an ICP-MS Elan 9000 mass spectrophotometer (Canada). The method of measuring the metal content in solid objects by the ISP-MS method was used. It was found that the gross content of Ag, Pb, Cd, Cu, Zn, W, Hg, B and especially Te, Bi, As and Sb in the soil was 2–840 times higher than the clark of the Earth’s crust. The total content of As, Zn, Pb, Sb and Cd in the soil was 1.3–7.0 times higher than the maximum permissible concentrations (MPC) and approximately permissible concentrations (APC) of chemicals, and the arsenic content exceeded the established limit by 240 times. The concentration of K, Sr, Ti, P, Zn, Ag, As and Cd in the leaves of the Miabe willow exceeded the clark of terrestrial plants by 1.5–3.0 times. A correlation was found between the concentration of Cd, Zn, B, Mn, Be, Ga and V in the leaves of the Miabe willow with the gross content of these elements in the soil of the plant’s growing sites. The storage elements in the plant were Se, P, Cd, Zn, B and K. The coefficient of biological accumulation of Se ranged from 1 to 40, Cd – 1.1–5.8, Zn – 0.5–2.6. Miabe willow is a promising plant for extracting cadmium and zinc from contaminated soils.

Accumulation of metals and metalloids in soil cover, road dust, and their PM10 fraction in Ulan-Ude: Spatial variation and source apportionment

Coal-fired thermal power plants remain one of the primary sources of electricity generation in the Asian part of Russia. However, coal combustion leads to severe environmental pollution. This study attempts to assess this impact in a large city in Eastern Siberia, Ulan-Ude, the capital of Buryatia, where coal is widely used in thermal power plants and for stove heating. The accumulation of trace metals (MMs) in the upper soil horizons, road dust, and their fine PM10 fraction was evaluated. The coal, ash, soil and road dust samples were analyzed using inductively coupled plasma-mass spectrometry (ICP-MS/AES) to determine concentrations of As, Bi, Cd, Co, Cr, Cu, Mo, Ni, Pb, Sb, Sr, V, W, and Zn. The coal was enriched only in Sr compared to world coals, while the ash was depleted in all these MMs. Concentrations of all MMs were higher than the local natural soil background values, with priority pollutants in Ulan-Ude's soils identified as Cu, Pb, Sb, Cd, Zn, and W. For the first time, the primary sources of MMs were quantitatively assessed using the PMF receptor model. It was established that most MMs (As, Ni, Cr, Sr, V, Co, Bi) originated from mixed sources, including natural sources and emissions from coal combustion. Its contribution accounted for 32.6 % for the bulk soils and 25.4 % for the PM10 fraction. The contribution of exhaust and non-exhaust emissions was estimated as 19.2 % and 22.4 % for bulk soils and the PM10 fraction, respectively. The spatial distribution of the Total Pollution Index (TPI) for soils indicated that the pollution degree was highest in private residential areas (mean TPI = 24), suggesting an influence of coal combustion conditions (including temperature) on contamination levels. The PM10 fraction of soil was most polluted in the railway transport zone (mean TPI = 46). Approximately 8 % of Ulan-Ude's territory displayed maximum, extremely hazardous levels of pollution in soils and their PM10 fraction, posing a risk to human health. Road dust was enriched in Sr, Sb and Pb compared to the continental upper crust values. Bulk road dust exhibited a low level of pollution, while the Total Pollution Index for its PM10 fraction reached an extremely hazardous level (TPI > 128). The highest pollution levels in road dust and its PM10 fraction were observed on main roads. In large industrial cities, pollution from coal combustion occurs alongside other significant sources, including vehicular emissions, contributing to the diversity of total pollutant emissions.

Antimony (Sb)-doped Bi2S3 nanorod films for photoelectrochemical water splitting

Bi2S3 is a promising material for photoelectrochemical (PEC) water splitting due to its favorable optoelectronic properties, abundance of non-toxic elements, and chemical stability. However, pure Bi2S3 exhibits low photocurrent efficiency due to charge recombination and slow charge transport. To enhance its performance, we doped antimony (Sb) into the Bi2S3 matrix, improving both its physical and PEC characteristics. The Sb doping concentration was varied from 0 to 3.1 at.% in Bi2S3 films, which were fabricated through chemical bath deposition followed by annealing. Undoped Bi2S3 formed nanorods with a direct bandgap of 1.26 eV and achieved a photocurrent density of 4.5 mA/cm2 at 1.0 V vs Ag/AgCl. Sb doping at 0.9 at.% increased both crystallite size and nanorod density, resulting in a bandgap of 1.43 eV and a photocurrent density of 7.0 mA/cm2. At higher Sb concentrations (2.2 to 3.1 at.%), the nanorod size further increased, while the bandgap decreased to 1.20 eV, with a corresponding increase in photocurrent density to 8.6 mA/cm2. These results demonstrate that Sb doping significantly enhances the nanorod density, photocurrent, and stability of Bi2S3 photoelectrodes.