Antimony speciation in road dust and urban particulate matter in Valparaiso, Chile: Analytical and environmental considerations

Distribution, Metabolism, and Toxicity of Antimony Species in Wistar Rats. A Bio-Analytical Approach

This work studied the distribution, reactivity, and biological effects of pentavalent or trivalent antimony (Sb(V), Sb(III)) and N-methylglucamine antimonate (NMG-Sb(V)) in Wistar Rats. The expression of fibrosis genes such as α-SMA, PAI-1, and CTGF were determined in Liver, and Kidney tissues. Wistar rats were treated with different concentrations of Sb(V), Sb(III), As(V) and As(III), and MA via intra-peritoneal injections. The results indicated a noteworthy elevation in mRNA levels of plasminogen activator 1 (PAI-1) in the kidneys of rats that were injected. The main accumulation site for Sb(V) was observed to be the liver, from which it is primarily excreted in its reduced form (Sb(III)) through the urine. The generation of Sb(III) in the kidneys has been found to induce damage through the expression of α-SMA and CTGF, and also lead to a higher creatinine clearance compared to As(III).

Fate of antimony contamination generated by road traffic - A focus on Sb geochemistry and speciation in stormwater ponds

Although antimony (Sb) contamination has been documented in urban areas, knowledge gaps remain concerning the contributions of the different sources to the Sb urban biogeochemical cycle, including non-exhaust road traffic emissions, urban materials leaching/erosion and waste incineration. Additionally, details are lacking about Sb chemical forms involved in urban soils, sediments and water bodies. Here, with the aim to document the fate of metallic contaminants emitted through non-exhaust traffic emissions in urban aquatic systems, we studied trace element contamination, with a particular focus on Sb geochemistry, in three highway stormwater pond systems, standing as models of surface environments receiving road-water runoff. In all systems, differentiated on the basis of lead isotopic signatures, Sb shows the higher enrichment factor with respect to the geochemical background, up to 130, compared to other traffic-related inorganic contaminants (Co, Cr, Ni, Cu, Zn, Cd, Pb). Measurements of Sb isotopic composition (δ¹²³Sb) performed on solid samples, including air-exposed dusts and underwater sediments, show an average signature of 0.07 ± 0.05‰ (n = 25, all sites), close to the δ¹²³Sb value measured previously in certified reference material of road dust (BCR 723, δ¹²³Sb = 0.03 ± 0.05‰). Moreover, a fractionation of Sb isotopes is observed between solid and dissolved phases in one sample, which might result from Sb (bio)reduction and/or adsorption processes. SEM-EDXS investigations show the presence of discrete submicrometric particles concentrating Sb in all the systems, interpreted as friction residues of Sb-containing brake pads. Sb solid speciation determined by linear combination fitting of X-Ray Absorption Near Edge Structure (XANES) spectra at the Sb K-edge shows an important spatial variability in the ponds, with Sb chemical forms likely driven by local redox conditions: "dry" samples exposed to air exhibited contributions from Sb(V)-O (52% to 100%) and Sb(III)-O (<10% to 48%) species whereas only underwater samples, representative of suboxic/anoxic conditions, showed an additional contribution from Sb(III)-S (41% to 80%) species. Altogether, these results confirm the traffic emission as a specific source of Sb emission in surface environments. The spatial variations of Sb speciation observed along the road-to-pond continuum likely reflect a high geochemical reactivity, which could have important implications on Sb transfer properties in (sub)surface hydrosystems.

Trace Metal(loid) Migration from Road Dust to Local Vegetables and Tree Tissues and the Bioaccessibility-Based Health Risk: Impacts of Vehicle Operation-Associated Emissions

Traffic activities release large amounts of trace metal(loid)s in urban environments. However, the impact of vehicle operation-associated emissions on trace metal(loid) enrichment in road dust and the potential migration of these trace metal(loid)s to the surrounding environment remain unclear. We evaluated the contamination, sequential fraction, and bioaccessibility of trace metal(loid)s in urban environments by assessing their presence in road dust, garden vegetables, and tree tissues, including bark and aerial roots, at a traffic-training venue impacted by vehicle operation emissions and, finally, calculated the bioaccessibility-based health risk. The results indicated a significant accumulation of trace metal(loid)s in road dust, with the highest lead (Pb), cadmium (Cd), and antimony (Sb) concentrations in the garage entrance area due to higher vehicle volumes, frequent vehicle starts and stops, and lower speeds. Aerial roots exposed to hill start conditions exhibited the highest Pb, Zn, and Sb levels, potentially caused by high road dust resuspension, confirming that this tree tissue is an appropriate bioindicator. Sequential extraction revealed high percentages of carbonate-, Fe/Mn oxide-, and organic/sulphide-associated fractions of Pb, copper (Cu), and zinc (Zn) in road dust, while most Cd, Cr, Ni, and Sb occurred as residual fractions. According to the potential mobilizable fractions in sequential extraction, the in vitro gastrointestinal method could be more suitable than the physiologically based extraction test to evaluate the bioaccessibility-related risk of traffic-impacted road dust. The bioaccessibility-based health risk assessment of the road dust or soil confirmed no concern about noncarcinogenic risk, while the major risk originated from Pb although leaded gasoline was prohibited before the venue establishment. Furthermore, the cancer risks (CRs) analysis showed the probable occurrence of carcinogenic health effects from Cd and Ni to adults and from Cd, Cr, and Ni to children. Furthermore, the Cd and Pb concentrations in the edible leaves of cabbage and radish growing in gardens were higher than the recommended maximum value. This study focused on the health risks of road dust directly impacted by vehicle emissions and provides accurate predictions of trace metal(loid) contamination sources in the urban environment.

Spatial distribution and sources of potentially toxic elements in road dust and its PM10 fraction of Moscow megacity

For the first time, the contents of potentially toxic elements (PTEs) in road dust and in its PM₁₀ fraction were studied in Moscow from June 09 to July 30, 2017 on roads with different traffic intensities, inside courtyards with parking lots, and on pedestrian walkways in parks. The contents of PTEs in road dust and PM₁₀ fraction were analyzed by ICP-MS and ICP-AES. The main pollutants of road dust and its PM₁₀ fraction included Sb, Zn, W, Sn, Bi, Cd, Cu, Pb, and Mo. PM₁₀ was a major carrier of W, Bi, Sb, Zn, Sn (accounts for >65% of their total contents in road dust); Cu (>50%); and Cd, Pb, Mo, Co, Ni (30-50%). PM₁₀ fraction was 1.2-6.4 times more polluted with PTEs than bulk samples. Resuspension of roadside soil particles accounted for 34% of the mass of PTEs in road dust and for 64% in the PM₁₀ fraction. Other important sources of PTEs were non-exhaust vehicles emissions (~ 20% for dust and ~14% for PM₁₀) and industrial emissions (~20% and ~6%). The road dust and PM₁₀ particles were most contaminated in the central part of the city due to the large number of cars and traffic congestions. Local anomalies of individual PTEs were observed near industrial zones mainly in the west, south, and southeast of Moscow. In the yards of residential buildings the total enrichment of road dust and PM₁₀ with PTEs was only 1.1-1.5 times lower than that on major roads which poses a serious danger to the population spending a significant part of their lives in residential areas. The spatial pattern of the PTEs distribution in road dust and its PM₁₀ fraction should assist in more efficient planning of washing and mechanical cleaning of the road surface from dust to minimize the risk to public health.

On-line electrochemical preconcentration and electrochemical hydride generation for determination of antimony by high-resolution continuum source atomic absorption spectrometry

Trace concentrations of antimony in aquatic samples were determined by high resolution continuum-source atomic absorption spectrometry (HR-CS AAS) after electrochemical pre-concentration and electrochemical hydride generation. Antimony was electrochemically deposited in a microporous glassy carbon electrode as elemental antimony then was electrochemically converted at the same electrode surface to antimony hydride which was transported by argon gas to the quartz cuvette of the spectrometer. The detection limit and precision of the method are below 0.1 μg L^-1 and 3-5%, respectively. The method was employed for the determination of antimony in a CRM and water samples including surface, underground and waste water.

Speciation analysis of inorganic As and Sb in urban dust using slurry sampling and detection by fast sequential hydride generation atomic absorption spectrometry

In this work, a methodology for chemical speciation analysis of inorganic As and Sb in urban dust using slurry sampling and detection by fast sequential hydride generation atomic absorption spectrometry is proposed. Doehlert design and desirability function were used to find the optimum conditions for hydride generation (1.0 mol L^-1 HCl and 0.9% m v^-1 NaBH₄). The accuracy of the analytical method was evaluated by analysis of reference material fly ash (BCR 176R), addition and recovery tests for inorganic As species, and comparison of independent methods for Sb determination in urban dust samples. The determination of the total concentrations of As and Sb and their inorganic species presented good accuracy, between 80 ± 1 and 101 ± 6%. Precision was expressed as the relative standard deviation and was better than 4.7% (n = 3). The limit-of-quantification values were 0.23 and 1.03 mg kg^-1 for As and Sb, respectively. The methodology was applied to eight samples of dust collected in an urban area of Salvador and Jaguaquara cities, Bahia, Northeast, Brazil, with an aerodynamic size lower than 38 μm. Concentrations of pentavalent inorganic species (iAs⁵⁺ and iSb⁵⁺) in relation to trivalent species (iAs³⁺ and iSb³⁺) were found in urban dust collected in the city of Salvador, which are regarded as more toxic for both elements. The enrichment factor and geoaccumulation index (I_geo) values showed that for some samples, the concentrations of iAs and iSb presented strong enrichment and, and regarding environment, strong to moderately polluted by iAs and iSb, with an indication of anthropogenic contributions. The occurrence of these inorganic constituents in the urban area of Salvador can be related with intense industrial activities and vehicular traffic.

Hazardous trace elements in thoracic fraction of airborne particulate matter: Assessment of temporal variations, sources, and health risks in a megacity

The deleterious health effects of thoracic fractions seem to be more related to the chemical composition of the particles than to their mass concentration. The presence of hazardous materials in PM₁₀ (e.g., heavy metals and metalloids) causes risks to human health. In this study, twelve trace elements (Cd, Cr, Pb, Zn, Cu, Ni, Sn, Ba, Co, As, V, and Sb) in 315 samples of ambient PM₁₀ were analyzed. The samples were collected at an urban background site in a Latin American megacity (Bogota, Colombia) for one year. The concentrations and temporal variabilities of these elements were examined. According to the results, Cu (52 ng/m³), Zn (44 ng/m³), Pb (25 ng/m³), and Ba (20 ng/m³) were the traces with the highest concentrations, particularly during the dry season (January to March), which was characterized by barbecue (BBQ) charcoal combustion and forest fires. In addition, the differences between the results of weekdays and weekends were identified. The determined enrichment factor (EF) indicated that Zn, Pb, Sn, Cu, Cd, and Sb mainly originated from anthropogenic sources. Moreover, a speciation analysis of inorganic Sb (EF > 300) was conducted, which revealed that Sb(V) was the main Sb species in the PM₁₀ samples (>80%). Six causes for the hazardous elements were identified based on the positive matrix factorization (PMF) model: fossil fuel combustion and forest fires (60%), road dust (19%), traffic-related emissions (9%), copper smelting (8%), the iron and steel industry (2%), and an unidentified industrial sector (2%). Furthermore, a health risk assessment of the carcinogenic elements was performed. Accordingly, the cancer risk of inhalation exposure to Co, Ni, As, Cd, Sb(III), and Pb was negligible for children and adults at the sampling site. For adults, the adjusted Cr(VI) level was slightly higher than the minimal acceptable risk level during the study period (1.4 × 10^-6).

Physicochemical characterization and sources of the thoracic fraction of road dust in a Latin American megacity

Road dust has been identified as one of the main sources of outdoor PM₁₀ in Bogota (a Latin American megacity), but there are no studies that have analyzed the physicochemical characteristics and origins of its respirable fraction. A characterization of inorganic compounds (water soluble ions, major and trace elements, organic and elemental carbon) and an analysis of source contributions to the PM₁₀ fraction of road dust were carried out in this study. A total of twenty road dust samples, selected from representative industrial, residential and commercial areas, were swept and resuspended to obtain the thoracic fraction. Size distribution by laser diffraction and individual particle morphology by Scanning Electron Microscopy were also evaluated. The data obtained revealed that the volume (%) of thoracic particles was higher in samples from industrial zones where heavy vehicular traffic, industrial emissions and deteriorated pavements predominated. Crustal elements were the most abundant species, accounting for 49-62% of the thoracic mass, followed by OC (13-29%), water-soluble ions (1.4-3.8%), EC (0.8-1.9%) and trace elements (0.2-0.5%). The Coefficient of Divergence was obtained to identify the spatial variability of the samples. A source apportionment analysis was carried out considering the variability of chemical profiles, enrichment factors and ratios of Fe/Al, K/Al, Ca/Al, Ti/Al, Cu/Sb, Zn/Sb, OC/TC and OC/EC. By means of a PCA analysis, five components were identified, including local soils and pavement erosion (63%), construction and demolition activities (13%), industrial emissions (6%), brake wear (5%) and tailpipe emissions (4%). These components accounted for 91% of the total variance. The results provide data to understand better one of the main sources of PM₁₀ emissions in Bogota, such as road dust. These data will be useful to optimize environmental policies, and they may be used in future studies of human health and air quality modeling.

Contamination of soils by potentially toxic elements in the impact zone of tungsten‑molybdenum ore mine in the Baikal region: A survey and risk assessment

Mining of mineral resources exerts strong impact on the environment and leads to irreversible changes in vegetation, soils, atmosphere, surface and ground waters. The aim of this study is to assess the modern geochemical state of soil cover in Zakamensk, a city located in Buryat Republic (Russia) and known as one of the biggest ore mining center in the former Soviet Union. The center was operating for 68 years and closed 17 years ago. Soil-geochemical survey was conducted in 2012 and included collection of 103 soil samples in Zakamensk and 27 samples in the background areas. The bulk contents of 16 potentially toxic elements (PTEs) in the soil samples were determined by mass spectrometry and by atomic emission spectrometry with inductively coupled plasma. Background sites are characterized by increased concentrations of ore elements W and Mo. The mineral deposit development and physical and chemical weathering of tailings' material have led to a sharp increase in Bi, Cd, Cu, Mo, Pb, Sb, W and Zn levels in the soils of different land-use areas. Near the tailings, the concentration of Sb in soils was 356 times higher than in the background area; Cd - 70 times; Mo, Bi, Cu, and W - 42-55 times; Pb and As - 34-37 times; and Zn and Sn - 6-12 higher. In the north of the city a prominent anomaly of PTEs occurs in sandy sediments of the Modonkul floodplain. It was formed due to the washout and subsequent sedimentation of suspended matter carried by the Modonkul River from the Barun-Naryn, the Dzhida, and emergency tailings. So, the anthropogenic activities are the most important source of ore and accompanying elements in the urban soils. High levels of accessory elements also depends on natural factors such as physicochemical properties of soils, position in the landscape, and genesis of parent materials. The environmental assessment of topsoils in Zakamensk showed that Pb, Sb, Cd, and As concentrations exceeds the Russian MPCs by 1.7-7.8 times, which creates a significant hazard for the environment and adversely affects human health.

Сontamination of urban soils with heavy metals in Moscow as affected by building development

Building development in cities creates a geochemical heterogeneity via redistributing the atmospheric fluxes of pollutants and forming sedimentation zones in urban soils and other depositing media. However, the influence of buildings on the urban environment pollution is poorly understood. The aim of this study is to evaluate the barrier functions of urban development by means of a joint analysis of the contents of heavy metals and metalloids in the upper horizon of urban soils, their physicochemical properties, and the parameters of the buildings. The soil-geochemical survey was performed in the residential area of the Moscow's Eastern Administrative District (Russia). The parameters of the buildings near sampling points were determined via processing data from the OpenStreetMap database, 2GIS databases and GeoEye-1 satellite image. A high level of soil contamination with Cd, W, Bi, Zn, As, Cr, Sb, Pb, Cu was revealed, depending on building parameters. A protective function of the buildings for yards is manifested in the decreasing concentrations of As, Cd, Co, Cr, Mo, Ni, Pb, Sb, Sn, W by 1.2-3 times at distances of <23-36 m from the buildings with their total area ≥660 m² and the height ≥7.5-21 m. An opposite effect which enhances concentrations of Bi, Cd, Co, Cr, Cu, Mo, Pb, Sb, Sn, W, Zn by 1.2-1.9 times is seen in "well-shaped" yards acting as traps under similar distances and heights, but at their average area ≥118-323 m², and total area ≥323-1300 m². The impact of these two building patterns on the soil contamination is only seen for certain directions of atmospheric flows. Buildings located in the northwestern sector relative to the sampling point protect the latter from the aerial pollution.

Occurrence of selected elements (Ti, Sr, Ba, V, Ga, Sn, Tl, and Sb) in deposited dust and human hair samples: implications for human health in Pakistan

The current study determined, for the first time, the levels of titanium (Ti), strontium (Sr), barium (Ba), vanadium (V), gallium (Ga), tin (Sn), thallium (Tl), and antinomy (Sb), in deposited dust, and human hair collected from general population of different geographical areas of Pakistan. All the samples were prepared by microwave digestion and measured by ICP-MS. The results showed that on deposited dust samples, the detected elements followed the descending trend as: Ti > Sr > Ba > V > Ga > Sn > Tl > Sb similar to the upper continental crust. The deposited dust samples from low elevation areas exhibited highest levels of all studied elements (except antimony which was higher in soil samples from mountainous areas), followed by rive plains, mountainous areas, and highland valleys. In contrast, on human hair samples, the elements followed the descending trend as: Sr > Ba > Ti > Ga > V > Sn > Sb > Tl respectively. Ba, Ga, and V concentrations were higher in soil samples from lower elevation Indus plain, and Sr, Tl, Sb, and Ti were higher in samples from mountainous areas. The bioaccumulation trend of all studied elements was in descending order as follows: Sb, Ga, Sn, Ba, Sr, Ti, V, Tl, respectively. Principal component analysis (PCA) and correlation matrix evidenced both geological influences and anthropogenic activities as potential sources of these studied elements. On the other hand, the risk estimation (HI > 1) concluded that population were at higher health risk (non-carcinogenic) for Ga and Ti. All other studied rare elements were within safe limit for humans from all zones.

Mechanisms underlying the toxic effects of antimony species in human embryonic kidney cells (HEK-293) and their comparison with arsenic species

Antimony cytotoxicity was assessed in human embryonic kidney cells (HEK-293). Uptake, mitochondrial respiratory activity, ROS generation and diffusional kinetics were measured using fluorescence recovery after photobleaching (FRAP). Furthermore, the toxic effect induced by Sb was compared with As toxicity in regard to ROS generation and diffusional kinetics, which provides information on the protein aggregation process. Our results show a favored uptake of Sb(III) and a more severe effect, decreasing the mitochondrial activity more than in the presence of Sb(V). In comparison with As, the Sb species did not generate a significant increase in ROS generation, which was observed with As(III) and As(V). FRAP analysis yielded important information on the diffusion and binding dynamics of live cells in presence of these metalloids. The mobile fraction showed a strong decrease with the As species and Sb(III). The diffusion rate and the k_off-rate were significantly decreased for the As and Sb species but were more strong in the presence of As(III).

Study of conformational changes and protein aggregation of bovine serum albumin in presence of Sb(III) and Sb(V)

Antimony is a metalloid that affects biological functions in humans due to a mechanism still not understood. There is no doubt that the toxicity and physicochemical properties of Sb are strongly related with its chemical state. In this paper, the interaction between Sb(III) and Sb(V) with bovine serum albumin (BSA) was investigated in vitro by fluorescence spectroscopy, and circular dichroism (CD) under simulated physiological conditions. Moreover, the coupling of the separation technique, asymmetric flow field-flow fractionation, with elemental mass spectrometry to understand the interaction of Sb(V) and Sb(III) with the BSA was also used. Our results showed a different behaviour of Sb(III) vs. Sb(V) regarding their effects on the interaction with the BSA. The effects in terms of protein aggregates and conformational changes were higher in the presence of Sb(III) compared to Sb(V) which may explain the differences in toxicity between both Sb species in vivo. Obtained results demonstrated the protective effect of GSH that modifies the degree of interaction between the Sb species with BSA. Interestingly, in our experiments it was possible to detect an interaction between BSA and Sb species, which may be related with the presence of labile complex between the Sb and a protein for the first time.

Speciation analysis of inorganic antimony in sediment samples from São Paulo Estuary, Bahia State, Brazil

This paper proposes an extraction procedure for the speciation analysis of inorganic antimony in sediment samples using slurry sampling and hydride generation atomic absorption spectrometry. The optimization step of extraction of the species was performed employing a full two-level factorial design (2(3)) and a Box-Behnken matrix where the studied factors in both experiments were: extraction temperature, ultrasonic radiation time, and hydrochloric acid concentration. Using the optimized conditions, antimony species can be extracted in closed system using a 6.0 M hydrochloric acid solution at temperature of 70 °C and an ultrasonic radiation time of 20 min. The determination of antimony is performed in presence of 2.0 M hydrochloric acid solution using HG AAS by external calibration technique with limits of detection and quantification of 5.6 and 19.0 ng L(-1) and a precision expressed as relative standard deviation of 5.6 % for an antimony solution with concentration of 6.0 μg L(-1). The accuracy of the method was confirmed by analysis of two certified reference materials of sediments. For a sample mass of sediment of 0.20 g, the limits of detection and quantification obtained were 0.70 and 2.34 ng g(-1), respectively. During speciation analysis, antimony(III) is determined in presence of citrate, while total antimony is quantified after reduction of antimony(V) to antimony(III) using potassium iodide and ascorbic acid. The method was applied for analysis of six sediment samples collected in São Paulo Estuary (Bahia State, Brazil). The antimony contents obtained varied from 45.3 to 89.1 ng g(-1) for total antimony and of 17.7 to 31.4 ng g(-1) for antimony(III). These values are agreeing with other data reported by the literature for this element in uncontaminated sediment samples.

Sb(V) reactivity with human blood components: redox effects

We assessed the reactivity of Sb(V) in human blood. Sb(V) reactivity was determined using an HPLC-HG-AFS hyphenated system. Sb(V) was partially reduced to Sb(III) in blood incubation experiments; however, Sb(III) was a highly unstable species. The addition of 0.1 mol L⁻¹ EDTA prevented Sb(III) oxidation, thus enabling the detection of the reduction of Sb(V) to Sb(III). The transformation of Sb(V) to Sb(III) in human whole blood was assessed because the reduction of Sb(V) in human blood may likely generate redox side effects. Our results indicate that glutathione was the reducing agent in this reaction and that Sb(V) significantly decreased the GSH/GSSG ratio from 0.32±0.09 to 0.07±0.03. Moreover, the presence of 200 ng mL⁻¹ of Sb(V) increased the activity of superoxide dismutase from 4.4±0.1 to 7.0±0.4 U mL⁻¹ and decreased the activity of glutathione peroxidase from 62±1 to 34±2 nmol min⁻¹ mL⁻¹.