Search Results (58)

Heavy metal contamination in rivers is a serious environmental and public health concern, especially in areas affected by mining. This study evaluated the levels of contamination and the associated ecological and carcinogenic risks in the sediments of the Cunas River, located in the central highlands of Peru. Sediment samples were collected from upstream and downstream sections. Several metals and metalloids were analyzed, including copper (Cu), chromium (Cr), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), vanadium (V), zinc (Zn), antimony (Sb), arsenic (As), and cadmium (Cd). The ecological risk assessment focused on ten of these elements, while carcinogenic and non-carcinogenic risks were assessed for seven metals selected based on their toxicological importance. The results showed that Cd and Pb concentrations were higher in the downstream section. Cd and As exceeded ecological risk thresholds. Regarding human health, As and Pb surpassed the acceptable limits for both the Hazard Index (HI) and the Potential Carcinogenic Risk (PCR). According to EPA guidelines, these values indicate a potentially significant lifetime cancer risk. The main exposure routes include direct contact with sediments and the consumption of aquatic organisms. Continuous monitoring, phytoremediation actions, and restrictions on the use of contaminated water are strongly recommended to reduce ecological and health risks. Full article

Mining waste often contains elevated concentrations of V, Cr, As, Sb, and Pb. Stibnite mining, during extraction and processing, generates waste that is deposited directly onto soil without vegetation cover, potentially leading to environmental pollution. This study assessed concentrations of potentially toxic elements (PTEs) in the rhizoids and stems-phyllidia of terrestrial mosses near antimony mines and used these mosses as biomonitors of soil contamination. Results obtained via energy-dispersive X-ray fluorescence spectrometry showed the highest concentrations of As, Sb, and Pb in mosses growing on mining rubble, reflecting elevated contaminant levels in the study area. Concentrations of As, Sb, and Pb differed significantly between mosses from mine rubble sites and those from forest and meander sites. Both rhizoids and stems/phyllidia of mosses from rubble sites showed high enrichment factors (EFs) for As, Sb, and Pb. Notably, PTEs concentrations in mosses from the forest area were lower than values reported for other regions, whereas concentrations in the mine rubble area exceeded those reported for other mining-polluted regions worldwide. Full article

Soil co-contamination with antimony (Sb) and arsenic (As) presents significant ecological and human health risks, demanding effective stabilization solutions. This study evaluated iron–manganese-modified hydrochar (FMHC) for synergistic Sb-As stabilization in contaminated smelter soils. Through 60-day natural aging and 30 accelerated aging cycles, we assessed stabilization performance using toxicity leaching tests (acid/water/TCLP), bioavailable fraction analysis, bioaccessibility assessment, and Wenzel sequential extraction. The key findings reveal that FMHC (5 wt%) achieves durable stabilization: (1) leaching concentrations remained stable post-aging (Sb: 0.3–4.5 mg·L⁻¹, >70% stabilization; As: <0.4 mg·L⁻¹, >94% stabilization); (2) bioavailable fractions showed maximum reductions of 64% (Sb) and 53% (As), though with some fluctuation; and (3) bioaccessible As was consistently reduced (55–77%), while Sb exhibited greater variability (maximum 58% reduction). Speciation analysis revealed similar stabilization pathways: Sb stabilization resulted from decreased non-specifically and specifically adsorbed fractions, while As stabilization involved the reduction in non-specifically/specifically adsorbed and amorphous to poorly crystalline Fe/Al hydrous oxide-bound fractions. These transformation mechanisms explain FMHC’s superior performance in converting labile Sb/As into stable forms, offering a sustainable solution for the green remediation of Sb-As co-contaminated soils in mining areas. Full article

Revegetation is considered a sustainable option for mine area remediation. However, the sustainability and risk evolution of revegetation for large antimony mine slag remain incompletely understood. In this study, we focused on the revegetation project of the waste slag heap of XKS, the world’s largest antimony mine. Systematically analyzed the physicochemical properties, total metal(loid) content, and BCR sequential extraction and applied the modified comprehensive pollution risk assessment (MCR) method to evaluate ecological risk evolution. The results showed that revegetation can effectively increase the nutrient content, and the total content of nitrogen and phosphorus maximally increased by 5.15 and 1.89 times, respectively, after 10 years of remediation. Long-term revegetation could mitigate the metal(loid) contamination, and the average contents of As and Sb decreased by 88.72–93.18% and 93.47–89.87%, respectively. BCR analysis showed that the percentage of residual As and residual Sb increased from 64.75% and 85.88% to 78.38% and 91.58%, respectively. The MCR assessment method showed that revegetation could effectively reduce the ecological risk level. This study provides important multidimensional evidence for the ecological restoration of antimony mining areas, which can provide practical guidance for subsequent slag management and risk control. Full article

Active and abandoned mining sites are significant sources of heavy metals and metalloid pollution, leading to serious environmental issues. This study assessed the environmental risks posed by potentially toxic elements (PTEs), specifically arsenic (As) and antimony (Sb), in the Technosols (mining residues) of the former Pejão coal mine complex in Northern Portugal, a site impacted by forest wildfires in October 2017 that triggered underground combustion within the waste heaps. Our methodology involved determining the “pseudo-total” concentrations of As and Sb in the collected heap samples using microwave digestion with aqua regia (ISO 12914), followed by analysis using hydride generation-atomic absorption spectroscopy (HG-AAS). The concentrations of As an Sb ranging from 31.0 to 68.6 mg kg⁻¹ and 4.8 to 8.3 mg kg⁻¹, respectively, were found to be above the European background values reported in project FOREGS (11.6 mg kg⁻¹ for As and 1.04 mg kg⁻¹ for Sb) and Portuguese Environment Agency (APA) reference values for agricultural soils (11 mg kg⁻¹ for As and 7.5 mg kg⁻¹ for Sb), indicating significant enrichment of these PTEs. Based on average I_geo values, As contamination overall was classified as “unpolluted to moderately polluted” while Sb contamination was classified as “moderately polluted” in the waste pile samples and “unpolluted to moderately polluted” in the downhill soil samples. However, total PTE content alone is insufficient for a comprehensive environmental risk assessment. Therefore, further studies on As and Sb fractionation and speciation were conducted using the Shiowatana sequential extraction procedure (SEP). The results showed that As and Sb levels in the more mobile fractions were not significant. This suggests that the enrichment in the burned (BCW) and unburned (UCW) coal waste areas of the mine is likely due to the stockpiling of lithic fragments, primarily coals hosting arsenian pyrites and stibnite which largely traps these elements within its crystalline structure. The observed enrichment in downhill soils (DS) is attributed to mechanical weathering, rock fragment erosion, and transport processes. Given the strong association of these elements with solid phases, the risk of leaching into surface waters and aquifers is considered low. This work underscores the importance of a holistic approach to environmental risk assessment at former mining sites, contributing to the development of sustainable remediation strategies for long-term environmental protection. Full article

The geopolitical and economic situation impacts raw materials demand. As principal ore deposits reach exhaustion, the study of new sources of raw materials becomes essential. Therefore, mining wastes emerge as alternative sources of raw materials. Their physicochemical properties, such as small particle size or concentration of some metals of interest, enhance reprocessing. A number of critical raw materials (As, Co, Cu, Sb) and base metals (Pb, Zn), as well as precious metals (Ag), were found present in an abandoned tailing deposit composed by finely grounded washed roasted pyrites within the Iberian Pyrite Belt. Copper leaching from a sample of this deposit was investigated. Two hydrometallurgical approaches were studied: acidic leaching with and without activated carbon; and alkaline leaching with glycine solutions. Leaching tests were carried out during 24 h at ambient and moderate temperatures (60 °C). In acidic medium, the maximum copper extraction varied from 88 to 92.5%, while in alkaline medium, the maximum copper extraction was in the range of 71%–76%. Using activated carbon and H₂O₂ seemed to slightly promote the copper extraction with the maximum extraction (92.5%) after 2 h of leaching at 60 °C. Complementarily, above 50% of the zinc and cobalt contained were extracted. In contrast, temperature in alkaline conditions played a key role in reaction speed, but also in precipitation of copper insoluble compounds. In addition, the glycine solution at pH 10–10.5 showed high selectivity for copper over zinc, iron, lead, arsenic, and antimony. Two extra tests at pH above 12 showed arsenic dissolution (up to 51% at pH 12.5). Full article

The historical industrial waste deposit Gater was used to dispose of different metallurgy wastes from lead and zinc production. The metallurgical waste deposit was situated in the open space, between the tailing waste deposit Žitkovac and river Ibar flow. Large amounts of lead-containing wastes are produced in the non-ferrous metallurgical industry, such as lead ash and lead slag generated in Pb smelting, lead anode slime, and lead sludge produced in the raw lead refining process. In addition to the lead concentration, numerous valuable components are found in the lead refinery waste from the group of Critical Raw Materials, such as antimony, arsenic, bismuth, copper, nickel, magnesium, scandium, as well as Rare-Earth Elements. Samples with eight characteristic points were taken to obtain relevant data indicating a possible recycling method. The chemical composition analysis was conducted using ICP; the scanning was completed using SEM-EDS. The mineralogical composition was determined by using XRD. The chemical analysis showed a wide range of valuable metal concentrations, from Ag (in the range from 14.2 to 214.6, with an average 86.25 mg/kg) to heavy metals such as Cu (in the range from 282.7 to 28,298, with an average 10,683.7 mg/kg or 1.0683% that corresponds to some active mines), Ni and Zn (in the range from 1.259 to 69,853.4, with an average 14,304.81 mg/kg), Sc (in the range from 2.4 to 75.3, with an average 33.61 mg/kg), Pb (in the range from 862.6 to 154,027.5, with an average 45,046 mg/kg), Sb (in the range from 51.7 to 18,514.7, with an average 2267.8 mg/kg), Ca (in the range from 167.5 to 63,963, with an average 19,880 mg/kg), Mg (in the range from 668.3 to 76,824.5, with an average 31,670 mg/kg), and As (in the range from 62.9 to 24,328.1, with an average 5829.53 mg/kg). The mineralogy analysis shows that all metals are in the form of oxides, but in the case of As and Fe, SEM-EDS shows some portion of elemental lead, pyrite, and silica-magnesium-calcium oxides as slag and tailing waste residues. The proposed recovery process should start with leaching, and further investigation should decide on the type of leaching procedure and agents, considering the waste’s heterogeneous nature and acidity and toxicity. Full article

The effect of low-molecular-weight dissolved organic matter (LDOM) on antimony enrichment in groundwater remains unclear. In this study, the spectroscopic and molecular characteristics of high- and low-Sb groundwater are compared using optical spectrophotometry, ultrafiltration, and Fourier transform ion cyclotron resonance mass spectrometry. The results demonstrated that although the mean DOM concentration in LDOM groundwater (3.98 mg/L) accounted for only 69.22% of the mean DOM concentration, the proportion of Sb(V) within the total Sb varied between 80.29% and 99.56%. LDOM was characterized by higher biological and fluorescence index values, a greater H/C ratio, and reduced double-bond equivalent values compared with high-molecular-weight dissolved organic matter. High abundances of LDOM can enhance the primary enrichment of Sb(V) within the total Sb concentration via competitive adsorption and, as energy and electron acceptors for microbial communities facilitate Sb(III), oxidation within groundwater systems. This study provides new perspectives on understanding how DOM influences the migration and speciation transformation of Sb in groundwater environments. Full article

Antimony-resistant bacteria are potential natural resources for the bioremediation of mining soil pollution. A Raoultella sp. 64 strain was isolated from antimony-contaminated soil. To enhance its Sb resistance abilities, this strain was transported into space aboard the Shenzhou spacecraft for space breeding, resulting in a mutant strain, Raoultella sp. D9. The whole genomes of Raoultella sp. 64 and mutant strain Raoultella sp. D9 were sequenced, revealing the genomic information for the bacterium. Comparative genomic analysis was then carried out to identify differential functional genes. The adsorption conditions for Sb(III) were optimized and refined. Further, Fourier transform infrared spectroscopy (FTIR) was used to determine the adsorption of antimony. Results show that strain D9 exhibits a higher tolerance to Sb(III), and Sb resistance genes were identified in both Raoultella sp. 64 and D9. Analysis of the differential functional genes indicated that the increased copy number of plsX may lead to a higher lipid content in the cell membrane, thereby enhancing the cell’s resistance to heavy metals. Mutant strain D9 exhibited better biosorption capacity compared to strain 64. FTIR studies showed that key functional groups, including -OH, C-N, C-H, and C-O, are likely to have participated in Sb(III) biosorption. Further study of the differential functional genes could provide a basis for future research and the subsequent development of technologies for the remediation of Sb-contaminated sites. Full article

Antimony is a chemical element with diverse uses that falls into the range of a critical raw material. Although it appears in nature as stibnite, the mining of this mineralogical species is rare or uncommon, and it is the element that is basically recovered as a secondary material in the processing of various elements (such as gold and copper). Another source for the recovery of this element is the recycling of Sb-bearing wastes such as batteries and alloys. Once dissolved and in order to recover it from the different leachates, adsorption processes are the ones that seem to have, at least for the scientific community, the highest acceptance. This work reviews the most recent advances (in 2024) in the recovery of antimony from different sources using not only adsorption processes but also other technologies of practical interest. Full article

This study investigates the synthesis of SMS-Ti-Mn (SMS-Ti-Mn stands for spent mushroom substrate activated carbon-Ti-Mn) nanocomposites and their application in removing the heavy metal antimony from water. In the process of antimony mining and smelting, the concentration of antimony in the waste residue can still reach as high as 80.5 mg/L. In addition, the soil in the electronic waste dismantling area is severely contaminated with antimony. In short, antimony enters the environment in various ways from mining, smelting, and manufacturing to the final waste process and continuously migrates in different environmental media, increasing the environmental exposure risk of antimony pollution. Single-factor experiments and response surface methodology were employed to determine the optimal conditions, including the adsorption time, pH, and solid–liquid ratio. Material characterization was performed to understand the role of nano-metals, and adsorption kinetics were analyzed using the quasi-first-order kinetic model. The research results revealed that the optimal conditions for antimony removal were an adsorption time of 40 min, a pH of 4, and a solid–liquid ratio of 2:1 (mg/mL). Under these conditions, the nanocomposites showed an adsorption capacity of 10.502 mg/g, which was 5.8 times higher than that of iron coagulants, 11 times higher than that of manganese-modified activated carbon, and 1.7 times higher than that of iron–manganese sludge adsorbents. Characterization revealed enhanced functional groups (carbonyl, Ti=O, Mn=O), contributing to improved adsorption. Kinetic analysis indicated physical adsorption as the dominant mechanism, and the regression model accurately predicted the adsorption capacity. SMS-Ti-Mn nanocomposites offer a promising strategy for treating antimony-contaminated water, with strong potential for practical applications in water treatment. They can decompose naturally after use, reduce secondary pollution, and promote ecological balance. Secondly, agricultural waste treated with heavy metal removal can be used as a fertilizer and soil amendment to improve soil quality and promote sustainable agricultural development. Full article

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. Full article

Active biomonitoring of mercury (Hg) using non-indigenous moss bags was performed for the first time within and around the former Hg mining area of Abbadia San Salvatore (Mt. Amiata, central Italy). The purpose was to discern the Hg spatial distribution, identify the most polluted areas, and evaluate the impacts of dry and wet deposition on mosses. The exposed moss bags consisted of a mixture of Sphagnum fuscum and Sphagnum tenellum from an external uncontaminated area. In each site, two different types of moss bags, one uncovered (to account for the wet + dry deposition) and one covered (to evaluate the dry deposition), were exposed. The behavior of arsenic (As) and antimony (Sb) in the mosses was investigated to assess the potential relationship with Hg. GEM (Gaseous Elemental Mercury) concentrations were also measured at the same sites where the mosses were exposed, although only as a reference in the initial stages of biomonitoring. The results revealed that the main Hg emissions sources were associated with the former mining area of Abbadia San Salvatore, in agreement with the measured GEM concentrations, while arsenic and antimony were related to soil enriched in As-Sb waste material. The three elements registered higher concentrations in uncovered mosses with respect to the covered ones, i.e., wet deposition was the key factor for their accumulation on the uncovered mosses, while dry deposition was especially important for the covered samples in the mining area. Hg was accumulated in the mosses via GEM adsorption, uptake of particulate Hg, and precipitation via raindrops/snowfall, with almost no loss and without post-deposition volatilization. The results testified that the chosen biomonitoring technique was an extremely useful tool for understanding Hg transport and fate in a contaminated area. Full article

This study aims to reveal the extent of the impact of mining activities on groundwater in a specific mining area in Hunan Province, assess the current quality of groundwater in the study area, investigate the correlations among heavy metal elements, and understand the migration and enrichment processes of different elements in groundwater. The findings will provide scientific data support for the establishment of groundwater monitoring systems by local governments and environmental protection departments. This paper presents the monitoring work conducted on the current status of heavy metal ions in groundwater within a mining area. Sampling and analysis were performed to measure pH, total dissolved solids (TDS), manganese (Mn), arsenic (As), cobalt (Co), molybdenum (Mo), barium (Ba), antimony (Sb), and selenium (Se) in both groundwater and surface water surrounding the study area. An improved hierarchical ladder evaluation method was used to comprehensively assess the degree of heavy metal pollution in the groundwater of the mining area. Additionally, statistical analysis was conducted to examine the correlations between heavy metal evaluation factors and TDS. The results show that the TDS values at various water quality monitoring points range from 187.34 to 1359.67, with a median of 400 and an average of 460.83. Additionally, the analysis of heavy metal pollution characteristics indicates that the water bodies in the mining area are severely impacted by mining activities, falling into the category of severe pollution. Among the heavy metals, As and Sb are the most serious pollutants, while the other heavy metal evaluation factors are less affected by mining activities. Correlation analysis further reveals that the correlation coefficients between Mo and Se and between Se and TDS are 0.772 and 0.778, respectively, indicating strong correlations. The correlation coefficients between As and Sb, Ba and Sb, and Mo and TDS are 0.455, 0.55, and 0.499, respectively, indicating moderate correlations. Other factor pairs exhibit weak correlations or even negative correlations. Full article

Antimony is one of the world’s scarcest metals and is listed as a Critical Raw Material (CRM) for the European Union. To meet the increasing demand for metals in a sustainable way, one of the strategies that could be implemented would be the recovery of metals as by-products. This would decrease the amount of hazardous materials filling mining dumps. The present study investigates the potential for producing antimony as a by-product at the Olympias separation plant in Northern Greece. This plant works a skarn mineralization that shows interesting amounts of Sb. Boulangerite (Pb₅Sb₄S₁₁) reports on Pb concentrate levels reached 8% in the analyzed product. This pre-enrichment is favorable in terms of boulangerite recovery since it can be separated from galena through froth flotation. Boulangerite distribution in the primary ore is quite heterogeneous in terms of the inclusion relationships and grain size. However, a qualitative assessment shows that the current Pb concentrate grain size is too coarse to successfully liberate a good amount of boulangerite. The use of image analysis and textural assessments is pivotal in determining shape factors and crystal size, which is essential for the targeting of flotation parameters during separation. The extraction of antimony as a by-product is possible through a two-step process; namely, (i) the preliminary concentration of boulangerite, followed by (ii) the hydrometallurgical extraction of the antimony from the boulangerite concentrate. The Olympias enrichment plant could therefore set a positive example by promoting the benefits of targeted Sb extraction as a by-product within similar sulfide deposits within the European territory. Full article