Sb Uptake Research Articles

Uptake, tolerance, and detoxification mechanisms of antimonite and antimonate in Boehmeria nivea L

Boehmeria nivea L. (ramie) is a promising phytoremediation plant for antimony (Sb)-contaminated soils. However, the uptake, tolerance, and detoxification mechanisms of ramie to Sb, which are the basis for finding efficient phytoremediation strategies, remain unclear. In the present study, ramie was exposed to 0, 1, 10, 50, 100, and 200 mg/L of antimonite (Sb(III)) or antimonate (Sb(V)) for 14 days in hydroponic culture. The Sb concentration, speciation, subcellular distribution, and antioxidant and ionomic responses in ramie were investigated. The results illustrated that ramie was more effective in the uptake of Sb(III) than Sb(V). Most of the Sb accumulated in ramie roots, with the highest level reaching 7883.58 mg/kg. Sb(V) was the predominant species in leaves, with 80.77–96.38% and 100% in the Sb(III) and Sb(V) treatments, respectively. Immobilization of Sb on the cell wall and leaf cytosol was the primary mechanism of accumulation. Superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) contributed significantly to root defense against Sb(III), while CAT and glutathione peroxidase (GPX) were the major antioxidants in leaves. CAT and POD played crucial roles in the defense against Sb(V). B, Ca, K, Mg, and Mn in Sb(V)-treated leaves and K and Cu in Sb(III)-treated leaves may be related to the biological processes of Sb toxicity mitigation. This study is the first to investigate the ionomic responses of plants toward Sb and could provide valuable information for the phytoremediation of Sb-polluted soils.

Geochemical analyses of metal(loid) fractions do not predict plant uptake behavior: Are plant bioassays better tools to predict mine rehabilitation success?

Management of metal(loid) tailings at historic sites presents environmental hazards usually requiring rehabilitation to mitigate pollution risks. Strategies employed include capping or establishing vegetation directly, which requires tailings assessments to determine suitable rehabilitation approaches. Assessments are typically geochemical analyses, but plant based approaches may provide a more accurate measure of revegetation success although they are often limited to germination indices. This study uses the plant bioassay (Rhizotest™) with common geochemical assessment to predict plant uptake of metal(loid)s and the subsequent likely rehabilitation success. Pb/Zn tailings from five legacy sites within the UK and Ireland were characterized for pH, EC, water soluble and CaCl2-extractable content and aqua regia extractable content. Uptake of Sb, As, Cd, Cu, Ca, Mg, Mn, Zn, Pb was determined in shoots and roots of Lolium perenne.Total Zn, Pb, Sb, Cd and As in tailings ranged from 694 to 2683 mg kg−1, 1252 to 8072 mg kg−1, 14 to 148 mg kg−1, 1.3 to 44 mg kg−1 and 1.3 to 45 mg kg−1, respectively. The only correlation found between total and water soluble or CaCl2-extractable metal(loid) contents was for Cd, where r = 0.8 for total and CaCl2-extractable fractions. Limited uptake and translocation risk was identified for major contaminants Zn and Pb in most tailings samples but in some cases exceedance of phytotoxic threshold values occurred that was not reflected in geochemical analysis. Crucially, although total Cd and Sb content was relatively low (< 20 mg kg−1) in some tailings, elevated plant content for some samples highlights phytotoxic risk from minor elements. Results indicate that screening based on geochemical content is not sufficiently predictive of metal(loid) phytoavailability to reliably inform mine rehabilitation strategies. We therefore strongly recommend that geochemical analyses are supplemented with plant based bioassay to plan mine tailings revegetation and reduce risk of wider ecosystem metal(loid) transfer.

Immobilization and phytoavailability of antimony (Sb) in contaminated agricultural soils amended with composted manure

A pot experiment was conducted to assess the Sb phytoavailability and its accumulation in the wheat before and after remediation, using the composted manure of poultry and sheep, and a chemical amendment (limestone). The present study evaluates the effects of amendments on Sb bioavailability in different soils and investigates the relationship between bioaccumulated Sb and its availability in spiked soils using two different single extraction methods. Furthermore, a sequential extraction procedure was used to measure different fractions of Sb in soil, in order to assess the effect of remediation. The results revealed that bioavailability of Sb were highly affected by the three soil amendments on plant height, uptake of Sb by wheat. Poultry compost (Pc) and Sheep compost (Sc) increased the residual fraction of Sb in soils, and decreased the Sb uptake by wheat, enhanced the height, biomass and dry yield of the wheat crop. While the residual fraction of Sb in soils didn't obviously increased by adding Chemical (limestone) in the four soils. It is concluded that uptake of Sb in the soils significantly decreased with the addition of amended materials in the Sb spiked soils, and poultry compost is the most effective. In the lower level of Sb contaminated soils remediated by poultry compost (Pc), the uptake of Sb in wheat decreased 63.1–74.4 %, 68.7–79.0 %, 68.9–76.9 % and 66.3–82.6 % in S1, S2, S3, S4, compared to the contaminated soils without amendments, respectively.

Uptake, speciation and detoxification of antimonate and antimonite in As-hyperaccumulator Pteris Cretica L

Antimony (Sb) and arsenic (As) are chemical analogs, but their behaviors in plants are different. To investigate the Sb uptake, translocation and speciation in As-hyperaccumulator P. cretica, a hydroponic experiment was conducted. In this study, P. cretica was exposed to 0.2-strength Hoagland nutrient solution, which contained 0.5 or 5 mg/L antimonite (SbIII) or antimonate (SbV). After 14 d exposure, P. cretica took up 1.4–2.8 times more SbIII than SbV. Since P. cretica was unable to translocate Sb, its roots accumulated >97% Sb with the highest at 7965 mg/kg. In both SbIII and SbV treatments, SbIII was the predominant species in P. cretica, with 90–100% and 46–100% SbIII in the roots. As the first barrier against Sb to enter plant cells, more Sb was accumulated in cell wall than cytosol or organelles. The results suggest that P. cretica may detoxify Sb by reducing SbV to SbIII and immobilizing it in root cell walls. Besides, the presence of SbIII significantly reduced the concentrations of dissolved organic C including organic acids in P. cretica root exudates. Further, increasing Sb levels promoted P accumulation in the plant, especially in the fronds, which may help P. cretica growth. The information from this study shed light on metabolic transformation of Sb in As-hyperaccumulators P. cretica, which helps to better understand Sb uptake and detoxification by plants.

The impact of phosphate on the interaction of Sb(III) with ferrous sulfide

Phosphate may affect the behavior of metal(loid)s in environments, so the interaction of Sb(III) with FeS affected by phosphate was investigated in this study. Sb(III) was reacted with synthesized FeS in solution at pH 5.5, 7.0, and 9.0 with and without the addition of phosphate. The concentrations of Fe(II), Sb(III), and phosphate in the solution were monitored, and the solid phases were examined by XRD, TEM, and XPS. For the interaction of Sb(III) with FeS in the absence of phosphate, the formation of Sb2S3 was very important at pH 5.5 and 7.0, whereas Sb(III) adsorption was the dominant process at pH 9.0. The interaction of Sb(III) with FeS could be significantly affected by phosphate, and this impact was dependent of pH and phosphate concentration. At pH 5.5 and 7.0, the effect of phosphate varied markedly with increasing phosphate concentration. Low phosphate loadings (9.5 and 19 mg/L) had a negligible effect on the mobility of Sb(III), while high phosphate loadings (95 and 475 mg/L) notably enhanced the uptake of Sb(III) by FeS. In the case of high phosphate loadings, Fe3(PO4)2‧8H2O was formed and resulted in the dissolution of FeS, which was favorable for the formation of Sb2S3 and consequently the uptake of Sb(III). In the experiments at pH 9.0, the addition of phosphate only resulted in minor desorption of Sb(III) because FeS was very stable and consequently both Fe3(PO4)2‧8H2O and Sb2S3 were unlikely to be formed. The results of this work may help to better understand the effect of phosphate on the behavior of Sb in some anoxic environments where FeS is present.

Effects of Antimony on Rice Growth and Its Existing Forms in Rice Under Arbuscular Mycorrhizal Fungi Environment.

Arbuscular mycorrhizal fungi (AMF) can form symbiotic relationships with most terrestrial plants and regulate the uptake and distribution of antimony (Sb) in rice. The effect of AMF on the uptake and transport of Sb in rice was observed using pot experiments in the greenhouse. The results showed that AMF inoculation increased the contact area between roots and metals by forming mycelium, and changed the pH and Eh of the root soil, leading to more Sb entering various parts of the rice, especially at an Sb concentration of 1,200 mg/kg. The increase in metal toxicity further led to a decrease in the rice chlorophyll content, which directly resulted in a 22.7% decrease in aboveground biomass, 21.7% in underground biomass, and 11.3% in grain biomass. In addition, the antioxidant enzyme results showed that inoculation of AMF decreased 22.3% in superoxide dismutase, 9.9% in catalase, and 20.7% in peroxidase compared to the non-inoculation groups, further verifying the negative synergistic effect of AMF inoculation on the uptake of Sb in rice. The present study demonstrated the effect of AMF on the uptake and transport of Sb in the soil–rice system, facilitating future research on the related mechanism in the soil–rice system under Sb stress.

Risk assessment of using phosphate and calcium fertilisers for continuously flooded rice cultivation in a soil co-contaminated with cadmium and antimony

Antimony (Sb) pollution is causing serious concerns in some regions globally, such as around the XiKuangShan mine in China, which is the largest Sb mine in the world. However, remediation measures are scarce. In this study, we assessed the effects of two fertilisers, sodium dihydrogen phosphate (NaH2PO4 at 200, 500 and 2000 mg kg−1) and calcium chloride (CaCl2 at 20, 80 and 200 mg kg−1), on uptake by rice (Oryza sativa L.) of Sb, cadmium (Cd) and arsenic (As) from contaminated soil under flooded conditions. Despite a very low soil As concentration (10.89 mg kg−1), the results showed that flooded conditions will result in excess accumulation of As in rice grains. NaH2PO4 generally enhanced the release of As and Sb by increasing pH and competitive adsorption in the soil, which resulted in their accumulation in many tissues of the rice plants. NaH2PO4 (200 mg kg−1) significantly reduced soil available Cd concentration by increasing soil pH, which resulted in a decrease in Cd concentration in the roots and husks. CaCl2 at 200 mg kg−1 decreased soil pH, and CaCl2 treatments increased the available Sb concentration, although not as much as NaH2PO4. Both NaH2PO4 and CaCl2 enhanced the formation of root iron plaques, and in many cases increased the concentrations of As, Cd and Sb in the root plaques, suggesting a storage role rather than a barrier of root iron plaques for plant uptake of As, Cd and Sb. CaCl2 at 200 mg kg−1 was the most effective treatment for reducing As, Sb and Cd concentrations in rice grains. We conclude that utilisation of fertilisers containing P on a soil co-contaminated by Sb and Cd poses a risk of Sb and As accumulation under continuous flooded conditions, whereas addition of CaCl2 at 200 mg kg−1 may control As, Sb and Cd accumulation in grains of rice plants under these conditions.

Antimony removal from water by pine bark tannin resin: Batch and fixed-bed adsorption

Antimony is present in water by natural causes but is also mobilized in the environment by anthropogenic activities, particularly mining. Considering its toxicological behavior, antimony removal from contaminated groundwater and mine effluents is necessary. In this work, Sb(III) and Sb(V) removal from aqueous solution was studied using a resin prepared from pine bark tannins. Subsequent iron loading of the tannin resin was tested, but this chemical modification was shown not to improve adsorptive properties. Tannin resin (unmodified form) presented a good ability to uptake antimony, with maximum adsorption capacities, evaluated in batch mode, of 30–33 mg g−1 (Sb(III), pH 6) and 16–47 mg g−1 (Sb(V), pH 2), depending on the particle size. The performance of the adsorbent was not affected by high levels of sulfate, which characterize most mining-impacted waters, but depending on Sb-load of the water it could be moderately affected by metal cations coexisting in solution. The applicability of the tannin resin on Sb(III) uptake was confirmed in continuous fixed-bed experiments. Breakthrough curves were obtained for different inlet adsorbate concentrations, bed heights, flow rates and aqueous media (distilled water and a simulated mine effluent). The adsorptive capacity of the tannin resin was practically maintained and adsorbent usage rates as low as 0.11 kg m−3 were determined to treat efficiently (90% removal) 1 mg-Sb(III) L−1 contaminated water. Overall, tannin resin is a bio-derived sorbent that shows affinity for antimony in both redox states, being stable in pH conditions commonly found in Sb-contaminated waters.

Efficient removal of antimonate from water by yttrium-based metal-organic framework: Adsorbent stability and adsorption mechanism investigation

Efficient decontamination of Sb(V) from water has long been an urgent task owing to its grave threat to human health. Herein, Y-based MOFs (MOF-Y and NH2-MOF-Y) were synthesized for effective adsorption of Sb(V) from aqueous solution, and the stability of the Y based MOFs were estimated. Kinetic and isotherms results indicated that the pseudo-second order kinetic (R2 > 0.90) and Langmuir isotherm models (R2 > 0.97) quite well described the adsorption of Sb(V) on Y-based MOFs, revealed that the uptake of Sb(V) on Y-based MOFs were followed by a monolayer chemical adsorption process. The maximum adsorption capacities of Sb(V) calculated from the Langmuir model were 161.3 and 151.5 mg/g for MOF-Y and NH2-MOF-Y, respectively. The Y-based MOFs exhibited strong water and chemical stability, it could be utilized for removal Sb(V) under wide pH range and various concentration of Sb(V). The spent adsorbents could be successfully regenerated by NaCl (5 mol/L) solution for further utilization without damaging the crystal structure of Y-based MOFs. X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS) results revealed that the formation of inner-sphere Y-O-Sb complex between Y-oxo-clusters and Sb(V) was the dominant adsorption mechanism, while the co-precipitation of Y3+ and Sb(V) was also partially contributed the Sb(V) adsorption. High stability together with high Sb(V) adsorption capacity and excellent recyclability endow the Y-based MOFs as promising adsorbents for Sb(V) removal from wastewater.

Silicon alleviates antimony phytotoxicity in giant reed (Arundo donax L.).

Silicon enhances photosynthetic efficiency, biomass, and lignification of root structures possibly limiting antimony translocation and mitigating phytotoxicity in giant reed plants. Antimony (Sb) is a non-essential metalloid causing toxic effects in plants. Silicon has been reported to impart tolerance against biotic and abiotic stress in plants. Fast-growing plant, giant reed (Arundo donax L.) is a promising energy crop, can be a suitable plant for phytoremediation. However, information regarding the tolerance capacity with respect to Sb toxicity and potential of Si to mitigate the Sb phytotoxicity in giant reed are very scarce. Rhizomes of giant reed were grown for ten weeks in hydroponics exposed to Sb, Si, and their combination wherein treatment without Sb/Si served as control. Effect of these treatments on rate of net photosynthesis and photosynthetic pigments, phytoextraction ability of Sb, Si and Sb uptake, plant biomass, and lignification and suberization of roots along with localization of Sb and Si were analysed. We found that Si considerably improved the growth and biomass of giant reed under Sb toxicity. Antimony reduced the photosynthesis and decreased the content of photosynthetic pigments, which was completely alleviated by Si. Silicon amendment to Sb treated plants enhanced root lignification. Silicon enhanced lignification of root structures probably restricted the Sb translocation. However, co-localization of Sb with Si has not been observed neither at the shoot nor at the root levels. Similarly, Sb was also not detected in leaf phytoliths. These findings suggest that Si treatment promotes overall plant growth by improving photosynthetic parameters and decreasing Sb translocation from root to shoot in giant reed by improving root lignification.

Removal of Antimony(V) from Drinking Water Using nZVI/AC: Optimization of Batch and Fix Bed Conditions.

Antimony (Sb) traces in water pose a serious threat to human health due to their negative effects. In this work, nanoscale zero-valent iron (Fe0) supported on activated carbon (nZVI) was employed for eliminating Sb(V) from the drinking water. To better understand the overall process, the effects of several experimental variables, including pH, dissolved oxygen (DO), coexisting ions, and adsorption kinetics on the removal of Sb(V) from the SW were investigated by employing fixed-bed column runs or batch-adsorption methods. A pH of 4.5 and 72 h of equilibrium time were found to be the ideal conditions for drinking water. The presence of phosphate (), silicate (), chromate () and arsenate () significantly decreased the rate of Sb(V) removal, while humic acid and other anions exhibited a negligible effect. The capacity for Sb(V) uptake decreased from 6.665 to 2.433 mg when the flow rate was increased from 5 to 10 mL·min−1. The dynamic adsorption penetration curves of Sb(V) were 116.4% and 144.1% with the weak magnetic field (WMF) in fixed-bed column runs. Considering the removal rate of Sb(V), reusability, operability, no release of Sb(V) after being incorporated into the iron (hydr)oxides structure, it can be concluded that WMF coupled with ZVI would be an effective Sb(V) immobilization technology for drinking water.

Effect of Municipal Solid Waste Compost on Antimony Mobility, Phytotoxicity and Bioavailability in Polluted Soils

The effect of a municipal solid waste compost (MSWC), added at 1 and 2% rates, on the mobility, phytotoxicity, and bioavailability of antimony (Sb) was investigated in two soils (SA: acidic soil; SB: alkaline soil), spiked with two Sb concentrations (100 and 1000 mg kg−1). The impact of MSWC on microbial activity and biochemical functioning within the Sb-polluted soils was also considered. MSWC addition reduced water-soluble Sb and favored an increase in residual Sb (e.g., by 1.45- and 1.14-fold in SA-100 and SA-1000 treated with 2% MSWC, respectively). Significant increases in dehydrogenase activity were recorded in both the amended soils, as well as a clear positive effect of MSWC on the metabolic activity and catabolic diversity of respective microbial communities. MSWC alleviated Sb phytotoxicity in triticale plants and decreased Sb uptake by roots. However, increased Sb translocation from roots to shoots was recorded in the amended soils, according to the compost rate. Overall, the results obtained indicated that MSWC, particularly at a 2% rate, can be used for the recovery of Sb-polluted soils. It also emerged that using MSWC in combination with triticale plants can be an option for the remediation of Sb-polluted soils, by means of assisted phytoextraction.

The mutation G133D on Leishmania guyanensis AQP1 is highly destabilizing as revealed by molecular modeling and hypo-osmotic shock assay

The Leishmania aquaglyceroporin 1 (AQP1) plays an important role in osmoregulation and antimony (Sb) uptake, being determinant for resistance to antimony. We have previously demonstrated that G133D mutation on L. guyanensis AQP1 (LgAQP1) leads to reduced Sb uptake. Here, we investigated the effects of G133D mutation on LgAQP1 structure, associated with Sb uptake and alterations in osmoregulation capacity. High confidence molecular models of wild-type LgAQP1 as well as the LgAQP1::G133D mutant were constructed and optimized via comparative homology modeling. Computational methods from the mCSM platform were used to evaluate the effects on protein stability and on its ability to bind to glycerol. Functional validation of the disruptive effect of the mutation on LgAQP1 was done by challenging the parasites with hypo-osmotic chock. Glycine 133 is on transmembrane helix 3, buried in the membrane in both open and closed conformation. G133D mutation was predicted to be highly destabilizing, as it alters the helical bundling arrangement in order to accommodate the aspartic acid side chain. The shift in helices also resulted in fewer favorable contacts with glycerol in the channel, which would explain the reduced affinity for similar small molecules as SbO3. Under hypo-osmotic condition, L. guyanensis AQP1G133D presented a 3-fold increase in cellular volume and pronounced delay to recover osmosis homeostasis when compared to the wild-type, a profile that was enhanced in LgAQP1−/− mutants. In conclusion, G133D is a highly disruptive mutation that will destabilize the monomer, compromise tetramer formation and alter pore conformation, leading to reduced Sb uptake and deficient osmoregulation.

Monolayer oscillations of the Sb desorption rate during molecular beam epitaxy of GaSb

In-situ desorption mass spectrometry (DMS) tool is used to report monolayer oscillations of the Sb desorption rate during molecular beam epitaxy (MBE) growth of GaSb and GaInSb. Oscillations in the Sb desorption rate appear to be correlated to the variation in the surface-step-density that periodically changes the additional uptake and expulsion of Sb beyond the fixed rate of consumption. This notion is corroborated by comparing the Sb DMS signal to the time derivative of the specular RHEED beam intensity.

Adsorption of lead and antimony in the presence and absence of EDTA by a new vermiculite product with potential recyclability.

A new two-step modification method has been proposed where 1.8% HCl and 3.1% HNO3 were applied to modify the interlayer of vermiculite (VMT). This product was given 90 °C of heat in 30% H2SO4 solution that was used for Pb (II) and Sb (III) adsorption. The EDTA presence on the individual adsorption was assessed. X-ray diffraction revealed that the VMT inter-stratified reflection through acid intercalation within the interlayer decreased the parallel gaps between the atoms, witnessing on the outer-sphere adsorption. The driving force was found electrostatic, which fits well with pseudo-second-order kinetics and Langmuir isotherm. The Pb (II) and Sb (III) uptake followed descending order adsorption with increasing concentration of chelating EDTA. Three consecutive desorption cycles revealed that the prepared adsorbent was suitable that may be regarded as a good candidate for complex wastewaters.

Alaskan plants and their assembled rhizosphere communities vary in their responses to soil antimony

Arctic and subarctic soils are undergoing rapid changes that influence vegetation, bacteria, and their interactions with each other and the environment. Our objective was to understand how rhizosphere bacterial communities from diverse Alaskan boreal and tundra habitats and common Alaskan plant species interact with an anthropogenic soil stressor. A variety of soil types associated with plant communities from Interior and Arctic Alaska were selected. Soils were seeded with a forb, grass, or tree, spiked with antimony (Sb) or kept as a control, and grown for 60 days under warm conditions. Plant growth and Sb uptake, rhizosphere prokaryote composition, and mycorrhizal colonization data were collected. Antimony altered rhizosphere bacterial community richness, diversity, and composition, dependent on soil type and plant identity. Of 20 rhizosphere bacterial orders, Burkholderiales proved most responsive to Sb, but the responses varied by plant species. Plant species' uptake of Sb were strongly influenced by soil biological, chemical, and physical properties. Picea glauca (white spruce) accumulated hyperaccumulator-level Sb concentrations in its roots in 2 of 6 soils. Future biotechnology applications to mitigate land degradation in this environment must acknowledge the complex interactions between vegetation, soils, microbes, and climate for successful utilization.

Interaction of aqueous antimony(III) with synthetic ferrous sulfide

Ferrous sulfide (FeS) is an important carrier for metal(loid)s in anoxic environments, but the effect of FeS on the behavior of Sb is poorly understood. This work investigated the interaction of Sb(III) with FeS under anoxic condition. FeS was synthesized and both equilibrium and kinetic experiments on the interaction of Sb(III) with synthesized FeS were conducted at various pH values. The final solid phases were examined by SEM, XRD, TEM, and XPS. The results showed that the uptake of Sb(III) by FeS increased as pH decreased. The kinetic experiment at pH 5 obviously showed that the temporal decrease of Sb(III)aq coincide with the partial dissolution of FeS. In contrast, both the concentrations of Sb(III)aq and FeS in the kinetic experiment at pH 9 did not vary with time. The examination of the solid phases revealed the formation of amorphous Sb2S3 in the experiments at pH 5 and 7.5. Different mechanisms were suggested to affect the interaction of Sb(III) with FeS under acidic and alkaline conditions. At pH 9, adsorption dominated in the interaction. The decrease of Sb(III)aq and the concomitant partial dissolution of FeS at pH 5 indicated the replacement of FeS by Sb2S3, which was more significant at lower pH. The replacement of FeS by Sb2S3 was a relatively slow process compared to the acidic dissolution of FeS. The result of this study helps understand the mobility of Sb in anoxic environments and may favor the remediation of Sb contamination by the use of FeS.

Exposure characteristics of antimony and coexisting arsenic from multi-path exposure in typical antimony mine area

In this study, samples of daily foods, drinking waters, surface waters, and soils were collected and screened to investigate the external exposure of Sb and As from various intake pathways in typical Sb mining area. Biomarker samples of residents were analyzed to monitor internal exposure characteristic of Sb and As in human body. Exposure dosages of As and Sb and transfer of Sb and As from environment to human body were estimated based on the external and internal exposure. The following results were obtained: daily intakes of food accounted for major intakes of both Sb and As, and highlighted the significance of foods intakes from rice and vegetable. The results of Monte Carlo simulations showed that total daily intake of Sb(n = 1444)and As(n = 1131) approximately reached 1.08 × 10−2 mg/kg/d and 1.19 × 10−3 mg/kg/d, in which 98.82% and 63.07% of residents have exceeded the threshold dosages of Sb and As. The contaminants contents in biomarkers indicated that Sb exhibited the similar internal exposure as As, while the total transfer rate of Sb from environment to human were estimated as approximately 2.04–2.40 times lower than As. This study also suggested that drinking water is another important pathway with high bioavailability and male resident may present higher priority than female in uptake of Sb and As. The paper suggested the similarity and difference on bioavailability existed in Sb and its group V elements, As, that would provide the essential information on exposure of Sb and As in the typical Sb mine area.

Highly efficient removal of antimonite (Sb (III)) from aqueous solutions by organoclay and organozeolite: Kinetics and Isotherms

Clays modified by cationic surfactants have been widely used for the removal of organic and inorganic anionic contaminants. However, their suitability for the removal of antimonite from aqueous solutions has not been systematically studied. In this study, hexadecylpyridinium chloride modified montmorillonite (HDPy+-M) and hexadecylpyridinium bromide modified zeolite (HDPy+-Z) were used to measure Sb(III) uptake from solutions containing 0.5–2.5 mM antimonite. Adsorption isotherms of antimonite were studied using the Langmuir and Freundlich equations. Adsorption kinetics were investigated using pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion models. The results of X-ray diffraction showed a large interlayer expansion for HDPy+-M, whereas the X-ray patterns of HDPy+-Z remained unchanged. Uptake of Sb(III) by both HDPy+-M and HDPy+-Z could be fitted well to the Langmuir isotherm, while the kinetics of adsorption could be described well using the pseudo-second-order model. Maximum adsorption capacities for Sb(III) uptake by HDPy+-M and HDPy+-Z were calculated to be 108.7 and 61.34 mg g−1, respectively. The results of the kinetic studies revealed that Sb(III) adsorption to HDPy+-Z was found to be quite fast and the reaction reached equilibrium in 8 h, whereas for HDPy+-M equilibration was attained within 24 h. The adsorption of antimonite onto both HDPy+-M and HDPy+-Z was found to be selective in the presence of Cl−1 and SO4−2 competitive anions. Considering the high affinity for Sb(III) uptake from solutions containing high concentrations of antimonite, both HDPy+-M and HDPy+-Z could be used as promising adsorbents for environmental applications.

Investigation of the antimony fractions and indigenous microbiota in aerobic and anaerobic rice paddies

The accumulation of antimony (Sb) by rice is a severe threat to exposed populations. Previous studies demonstrated that, compared to flooded (anaerobic) water management, dry cultivation management (aerobic) could substantially decrease As, an analog of Sb, uptake by rice. However, the effects of different water management strategies on the accumulation of Sb by rice are less understood. It is proposed that microorganisms play an important role in regulating Sb mobility in rice paddies. Hence, the current study compared the microbial communities in rice paddies receiving different water management, i.e., flooded (anaerobic) and dry (aerobic)) rice cultivation. Significant decrease in Sb uptake by rice, in both the roots and grains, was observed under the aerobic compared to the anaerobic conditions. This could partially be attributed to the differences in the microbial communities as shaped by the redox environment. In aerobic soils, the gene responsible for Sb oxidation (i.e., aioA) was significantly, while in anaerobic soils the gene responsible for Sb reduction (i.e., arrA) was enriched, suggesting that variation in redox conditions may trigger different microbial responses. Accordingly, geochemical analysis indicated that accumulation of Sb(III) was only observed under anaerobic conditions, but not under aerobic conditions. The environment-microbe interactions were distinct between the two treatments with a greater number of interactions between Sb fractions and the microbial assemblage under anaerobic conditions, while Eh was the most influential geochemical parameter under aerobic conditions. Finally, the presence of a core microbiome under the two conditions suggested the possibility of microorganisms that support rice growth, nutrition, and health. The reduction of Sb in rice grain significantly decreases Sb exposure to the residents in Sb contaminated regions, and should be considered for future rice cultivation practices.