Influence of ore processing activity on Hg, As and Sb contamination and fractionation in soils in a former mining site of Monte Amiata ore district (Italy)

Thermal desorption technique to speciate mercury in carbonate, silicate, and organic-rich soils

Thermal desorption is a well-assessed technique to speciate mercury (Hg) in soils and sediments. However, the effects related to the different matrices are still not properly assessed. In this study, thermal desorption was applied to Hg-free calcite mixed with Hg standard and soils rich in carbonate and silicate minerals, as well as organic matter. Hg0, HgCl2, HgO, α-HgS, β-HgS and organo-mercuric compounds were recognized, pointing out that the soil matrix operates notable differences in terms of breakdown temperatures of the Hg-compounds and suggesting that the mineralogical composition of soil has to be investigated before applying the thermal desorption technique. Furthermore, the presence of Hg0 was carefully evaluated since, as already observed, it forms Hg2+, which increases mercury mobility in the pedological cover with important consequences for those soils contaminated and located close to decommissioned or active mining areas and/or industrial sites (e.g. chloro-alkali industries). Experimental runs were thus carried out by using carbonate-, silicate- and organic-rich soils doped with liquid Hg. It was observed that Hg0 tends to be oxidized to form Hg+ and then Hg2+ as a function of soil matrix and reaction time. Surprisingly, the oxidation rate is rather fast, since after 42 days the initial content of Hg0 is halved, thus following an exponential decay. This implies that in Hg0-polluted areas, the fate of the resulting Hg2+ can be that to: i) be adsorbed by organic matter and/or Fe-Mn-Al oxides and/or ii) feed shallow aquifers. This study is a further step ahead to understand the behavior of Hg in contaminated soils from industrial and mining areas where liquid Hg is occurring in different soil matrices and may provide useful indications for remediation operations.

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

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

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

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

Unveiling the spatial differentiation drivers of major soil element behavior along traffic network accessibility

Advancements in transportation networks have induced a spatial-temporal convergence effect, accelerating socio-economic elements flow and dismantling the conventional "core-periphery" urbanization gradient. Accessibility of transportation networks emerges as a reliable indicator of urbanization. There has been a growing global and Chinese focus on the various forms of metal pollution in urban soil. This study aims to investigate the driving forces and effects of urbanization factors (Gross Domestic Product (GDP), value added of secondary industries (VA), night light (NL), population density (PD), and road density (Distance)), soil property factors (pH, electrical conductivity (EC), and total organic carbon (TOC)), and topographic factors (elevation (DEM), aspect, and slope) on toxic heavy metal elements (Cd, As, and Hg) and trace elements (Mn, Ti, V) in surface soil (0-20 cm) across varying accessibility levels in the Beijing-Tianjin-Hebei urban agglomeration. Results reveal significant influence of accessibility on Cd and Hg levels (p < 0.05), with higher accessibility areas displaying elevated element concentrations. According to the evaluation results of the single-factor pollution index, Cd and V have the highest pollution exceedance rates (93.18% and 75.76%, respectively). Moran's Index results highlight typical spatial clustering of elements, with hotspots in areas of high accessibility. Urbanization has led to distinct spatial agglomeration patterns in element concentrations and environmental factors. Geographic detector analysis reveal that in low accessibility areas, metal element pollution and distribution are influenced by a combination of complex factors, including soil properties (pH), terrain conditions (DEM), and the urbanization process (VA). In high accessibility areas, toxic heavy metal elements are primarily driven by urbanization factors, largely influenced by transportation activities, industrial development, and population density, while elements Mn, Ti, and V are still influenced by both natural processes and urbanization activities. These findings suggest that urbanization intensifies the impact on potential toxic elements in soil, and that trace elements are increasingly affected by urbanization, warranting further attention.

Tree-rings analysis to reconstruct atmospheric mercury contamination at a historical mining site

Mercury (Hg) is a global environmental concern due to its toxicity (especially high in methylated form) and the long-range distribution of its gaseous elemental form (GEM). Hg-contaminated areas, such as abandoned mining sites, pose intrinsic difficulties for their management and heavy monitoring costs. In these environments, plant-based solutions may play a key role in the ecosystem quality assessment and support remediation strategies, combining reliability and cost-effectiveness. In this study, we adopted a biomonitoring approach by using tree rings of four different species collected in the proximity of the mining-metallurgical area of Abbadia San Salvatore, central Italy, a major former Hg mining district whose reclamation is currently in progress. Our dendrochemical analysis was aimed at identifying the historical changes of local atmospheric Hg contamination and at singling out, for the first time in the study area, other potentially toxic elements (PTEs) associated with the past mining activity. Collected cores dated back to early as 1940 and provided the temporal patterns of atmospheric Hg emission vs the produced liquid quantities, so reconstructing the historical impact of the mining site on nearby terrestrial ecosystems and resident human population. Current GEM contamination was found about twenty times lower than that of the fully operational mine periods. From a first survey on other PTEs, thallium (Tl) and lead (Pb) appeared to be potentially associated with the mining activity, thus suggesting new working assumptions for further dendrochemical analyses and for the inclusion of Pb in human biomonitoring surveys of the Mt. Amiata area, actually not present in the control list. The results prompt a more thorough assessment by tracking for a longer time span a critical site that is an ideal open-field lab to study the ecophysiology of different tree species in relation to environmental behavior of PTEs for better-assessing wildlife and human exposures.

Exploring relationship of soil PTE geochemical and "VIS-NIR spectroscopy" patterns near Cu-Mo mine (Armenia)

PTE contamination of soils remains one of the global environmental concerns. The ways of detecting and monitoring PTE concentrations in soils varies including traditional field sampling accompanied by sample preparation and chemical analysis and state of the art visible and near-infrared (Vis-NIR) spectroscopic approaches. Among the different Machine Learning (ML) to extract soil information from spectra and to explore the relationship between spectral reflectance data and soil PTE content PLSR method is a well-established one to construct a soil PTE estimation model. This study aimed to explore the relationship of soil PTE geochemical and VIS-NIR spectroscopy characteristics in agricultural soils near Cu-Mo mine area in Armenia. PLSR method is applied to identify the links between the spectra and agricultural soil Ti, V, Cr, Mn, Fe, Co, Ba, Pb, Zn, Cu, Sr, Zr and Mo contents to reveal the potential of VIS-NIR spectroscopy in ex-situ monitoring of Kajaran soils. The results show that different portions of VIS-NIR spectra are responsible for Ti (1100-1200 nm, 2350-2500 nm), V (350-500 nm, 700-750 nm, 1000-1100 nm, 1400-2500 nm), Cr (1300-1400 nm, 1900-2100 nm) and Ba (450-500 nm, 600-800 nm, 1050-1700 nm, 2000-2100 nm, 2350-2400 nm) estimations through PLSR correspondingly. However, among the studied PTEs Ti and V, which shows significant negative correlations in VIS-NIR spectra registered at around 400-600 nm and 850-1150 nm regions, are remarkable and promising with the PLSR estimation results using VIS-NIR spectra Ti (R²_Test = 0.74), V (R²_Test = 0.71). This study shows that VIS-NIR spectroscopy has a high potential for the estimation of at least several PTE in soils and PLSR modelis reliable for deriving information from there.

Source apportionment of heavy metals in the soil at the regional scale based on soil-forming processes

Source apportionment is crucial to the prevention and control of heavy metals in the soil. The major methods focus on the identification of soil heavy metals from different pollution sources. However, they are unsuited to the source apportionment at a regional scale due to ignoring the spatial heterogeneity of heavy metal content caused by soil formation. Thus, we built a source apportionment model by introducing the weathering and leaching coefficients as the key parameters of soil-forming processes. In this study, we selected Liaohe Plain in China as the study area, which was the starting point of China's industrial development, with dense industrial areas and high levels of heavy-metal emission. Heavy metals concentrations in surface and deep soil of reference and grid points were collected as model data. The results showed that the average contribution rates of soil-forming process to Cd, Hg, As, and Pb were 82.7%, 85.2%, 88.6%, and 91.7%, respectively, and those of anthropogenic activities were 17.3%, 14.8%, 11.4%, and 8.3%, respectively. Spatial distribution of contribution rates showed the superposition of soil environmental background and pollution sources. This study provides a feasible method to quantify heavy metals contents from natural and anthropogenic sources at a regional scale.

New geochemical data for defining origin and distribution of mercury in groundwater of a coastal area in southern Tuscany (Italy)

A geochemical study was conducted in a coastal plain in the Orbetello Lagoon area in southern Tuscany (Italy), acquiring new data on groundwater, lagoon water, and stream sediment for insights into the origin, distribution, and behaviour of mercury in a Hg-enriched carbonate aquifer. The main hydrochemical features of the groundwater are ruled by the mixing of Ca-SO4 and Ca-Cl continental fresh waters of the carbonate aquifer and Na-Cl saline waters of the Tyrrhenian Sea and Lagoon of Orbetello. Groundwater had highly variable Hg concentrations (< 0.1-11 μg/L) that were not correlated with the percentage of saline water, depth in the aquifer, or distance from the lagoon. This excluded the possibility that saline water could be the direct source of Hg in groundwater and responsible for release of the element through interaction with the carbonate lithologies of the aquifer. The origin of Hg in groundwater could be ascribed to the Quaternary continental sediments overlying the carbonate aquifer because i) high Hg concentrations were found in the continental sediments of the coastal plain and in the contiguous lagoon sediments; ii) waters from the upper part of aquifer had the highest Hg concentrations; iii) Hg levels in groundwater increased with increasing thickness of the continental deposits. The high Hg content in the continental and lagoon sediments is geogenic due to regional and local Hg anomalies and to sedimentary and pedogenetic processes. It can be assumed that i) water circulating in these sediments dissolves the solid Hg-bearing constituents and mobilises this element mainly as chloride complexes; ii) Hg-enriched water moves from the upper part of the carbonate aquifer due to the cone of depression generated by intense pumping of groundwater by fish farms in the study area.

Air quality in post-mining towns: tracking potentially toxic elements using tree leaves

In this study, leaves of the evergreen holm oak Quercus ilex were used to assess airborne contamination of potentially toxic elements (PTEs) at five towns located on the slopes of the Mt. Amiata (central Italy), an area with a long history of mining and, more recently, an important district for the industrial exploitation of geothermal energy. PTE composition and covariance of washed and unwashed Q. ilex leaves of three different ages (6, 12 and 24 month-old) were used to identify atmospheric inputs of PTEs at residential areas, evaluate long-term adsorption and retention of PTEs by the leaves, thus providing an indication of potential human exposure. Moreover, the determination of foliar concentrations of major elements (C, N, S and P) allowed an assessment of the nutritional status of the investigated urban tree stands which excluded the existence of stress condition caused by air pollution or other disturbances. Results indicated that overall Pb, Cu, and Cd concentration were low in the investigated urban sites, if compared with similar studies conducted in larger Italian cities, denoting a low contribution of vehicular traffic to the atmospheric pathway. The five urban settlements were characterized by a specific profile of elements (Al, Ba, Hg and Sb) enriched in unwashed leaves, resulting from the distinct geochemical characteristics of the area and from diffuse (i.e., urban activity) and point sources of PTEs emission (i.e., brownfields, geothermal power plants). The latter sources primarily govern the distribution of Hg, whose contamination was found to be very localized close to a major abandoned mining area. Our data provided quantitative evidence of the spectrum of PTEs potentially impacting resident population and may prove useful in support of follow-up instrumental monitoring campaigns of air quality, as well as for human health and ecological risk assessments.

Multidisciplinary approach to the study of large-format oil paintings

Cultural heritage has become a keystone for comprehending our society, as it represents and reflects our origins, passions, beliefs and traditions. Furthermore, it provides fundamental information about specific temporary spaces, materials' availability, technology, artist's intention, and site weather conditions. Our aim was to develop a multidisciplinary approach with a main focus on investigating two Italian large-format paintings located in highly diverse environments such as the National Theater of Costa Rica. We monitored environmental conditions and quantified fungal aerial spores. Then, we determined regions of possible biodeterioration with the software MicroorganismPattern and used the software PigmentArrangement to elucidate the apparent colour of the paintings based on distribution and arrangement of the pigment crystals. Finally, we characterized eight genera of calcareous nannofossils found in the ground layers of the artwork. The former Men's Canteen at the National Theater of Costa Rica presented a mean air temperature of 23.5 [Formula: see text]C, a relative humidity of 72.7% and a concentration of CO[Formula: see text] of 570 ppm. The fungal aerial concentration was 1776 spores/m[Formula: see text]. The software MicroorganismPattern identified 32 sampling regions, out of which 11 were positive for microbial contamination. The software PigmentArrangement determined that the blue crystals (ultramarine pigment) had the shortest distances between themselves (29 [Formula: see text]m). Finally, the nanofossils identified enabled us to restrict the age of the material to a biostratigraphic interval ranging from Coniacian to Maastricthian ages. By using a multidisciplinary approach we were able to explore the diptych, suggest a set of minimally invasive perspectives in tropical environments to be used worldwide and obtain key information about the artist's artistic process, materials used along with better understand its state of conservation.

Evaluation of Pollution Level, Spatial Distribution, and Ecological Effects of Antimony in Soils of Mining Areas: A Review

The first global-scale assessment of Sb contamination in soil that was related to mining/smelting activities was conducted based on 91 articles that were published between 1989 and 2021. The geographical variation, the pollution level, the speciation, the influencing factors, and the environmental effects of Sb that were associated with mining/smelting-affected soils were analyzed. The high Sb values mainly occurred in developed (Poland, Italy, Spain, Portugal, New Zealand, Australia) and developing (China, Algeria, Slovakia) countries. Sb concentrations of polluted soil from mining areas that were reported in most countries significantly exceeded the maximum permissible limit that is recommended by WHO, except in Turkey and Macedonia. The soil Sb concentrations decreased in the order of Oceania (29,151 mg/kg) > North Africa (13,022 mg/kg) > Asia (1527 mg/kg) > Europe (858 mg/kg) > South America (37.4 mg/kg). The existing extraction methods for Sb speciation have been classified according to the extractant, however, further research is needed in the standardization of these extraction methods. Modern analytical and characterization technologies, e.g., X-ray absorption spectroscopy, are effective at characterizing chemical speciation. Conditional inference tree (CIT) analysis has shown that the clay content was the major factor that influenced the soil Sb concentration. Non-carcinogenic risks to the public from soil Sb pollution were within the acceptable levels in most regions. An Sb smelter site at the Endeavour Inlet in New Zealand, an abandoned open-pit Sb mine in Djebel Hamimat, Algeria, an old Sb-mining area in Tuscany, Italy, and Hillgrove mine in Australia were selected as the priority control areas. Cynodon dactylon, Boehmeria, Pteris vittata, and Amaranthus paniculatus were found to be potential Sb accumulators. All of the values of bioaccumulation factors for the crops were less than one. However, ingestion of Sb through crop consumption posed potential non-carcinogenic health risks, which should not be neglected. The soil variables (pH, Eh, total sulfur, carbon nitrogen ratio, total organic carbon, and sulfate), the total Sb and the bioavailable Sb, and heavy metal(loid)s (As, Pb, and Fe) were the major parameters affecting the microbial community compositions.

Pollution characteristics and environmental availability of toxic elements in soil from an abandoned arsenic-containing mine

Understanding the pollution characteristics and assessing the ecological risk of toxic metals in mine soil are crucial to controlling and managing risks in abandoned mine areas. In this study, the profile soil pollution characteristics and modified ecological risk of As, Cd, Hg, Pb, Sb, and Tl for both the different mining functional areas and the downstream impacted areas at a large-scale abandoned arsenic-containing mine were studied. Results showed that both the profile soils at the mining functional areas and the surface layer in downstream sites are heavily polluted by As, Cd, Hg, Sb, and Tl. As, Hg, Sb, and Tl mainly accumulated on soils with a depth of 0-1.5 m. In contrast, these metals in the mining site were gradually increased with soil depth above the bedrock strata. Cd and Pb were mainly concentrated at depth of 2.5-3.5 m in the smelting with by-product processing site. The speciation of metals in the profile soils mainly occurred in residual fraction. However, high levels of potential mobile As and Sb were found in mining soils and smelting surface soils, as well as Tl in deep soils at mining functional sites and top soils at downstream sites, with their mean contents in these areas arrived to 2950 mg kg^-1, 9.64 mg kg^-1, and 0.98 mg kg^-1, respectively. In addition, the modified ecological risk assessment (NIRI_m) values revealed a substantial ecological risk of As, Cd, Hg, and Sb in both the entire profile soils at the mining, smelting sites and topsoil (0-1.5 m) at the adjacent downstream site. In summary, the pollution characteristics and potential ecological risk of toxic metals in profile soils from the different functional sites at arsenic-containing mine were significantly different and suitable control strategies for available toxic elements should be adopted in the different functional sites of mine.

Accumulation, regional distribution, and environmental effects of Sb in the largest Hg-Sb mine area in Qinling Orogen, China

In this study, knowledge gaps on Sb concentration in rocks, ores, tailings, soil, river water, sediments, and crops of mine areas were identified and discussed in terms of contamination levels, spatial distribution, and environmental effects. Accordingly, Xunyang Hg-Sb mine, the largest Hg-Sb deposit in China as research region in this study, field sampling and laboratory analysis were conducted. The results showed elevated concentrations of Sb in the soil, sediment, and river water. The X-ray diffraction analysis indicated that the main minerals of the rocks were quartz, dolomite, calcite, and margarite. Based on the TESCAN integrated mineral analyzer analysis, the main ore minerals in the Gongguan mine were dolomite (93.97%), cinnabar (2.50%), stibnite (2.48%), calcite (0.38%), and quartz (0.38%). The μ-XRF analysis indicated that Sb distribution was similar to those of S and O, instead of those of Hg and As. The clear spatial variation of Sb concentration in environmental media, mines, tailings, and settling ponds affected Sb accumulation. Actinobacteriota, Proteobacteria, Acidobacteriota, and Chloroflexi were the dominant phyla in the soil. Patescibacteria, Proteobacteria, and Bdellovibrionota were negatively correlated with Sb in the soil (p < 0.05). Exposure to Sb through maize grain and cabbage consumption poses serious non-carcinogenic health risk for residents. This work provides a scientific basis for the environmental quality assessment of Sb mine areas and development of applicable guidelines.

Potentially Toxic Elements’ Contamination of Soils Affected by Mining Activities in the Portuguese Sector of the Iberian Pyrite Belt and Optional Remediation Actions: A Review

Both sectors of the Iberian Pyrite Belt, Portuguese and Spanish, have been exploited since ancient times, but more intensively during and after the second half of the 19th century. Large volumes of polymetallic sulfide ore were extracted in open pits or in underground works, processed without environmental concerns, and the generated waste rocks and tailings were simply deposited in the area. Many of these mining sites were abandoned for years under the action of erosive agents, leading to the spread of trace elements and the contamination of soils, waters and sediments. Some of these mine sites have been submitted to rehabilitation actions, mostly using constructive techniques to dig and contain the contaminated tailings and other waste materials, but the remaining soil still needs to be treated with the best available techniques to recover its ecosystem functions. Besides the degraded physical structure and poor nutritional status of these soils, they have common characteristics, as a consequence of the pyrite oxidation and acid drainage produced, such as a high concentration of trace elements and low pH, which must be considered in the remediation plans. This manuscript aims to review the results from studies which have already covered these topics in the Iberian Pyrite Belt, especially in its Portuguese sector, considering: (i) soils’ physicochemical characteristics; (ii) potentially toxic trace elements’ concentration; and (iii) sustainable remediation technologies to cope with this type of soil contamination. Phytostabilization, after the amelioration of the soil’s properties with organic and inorganic amendments, was investigated at the lab and field scale by several authors, and their results were also considered.

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

Antimony (Sb) is introduced into soils, sediments, and aquatic environments from various sources such as weathering of sulfide ores, leaching of mining wastes, and anthropogenic activities. High Sb concentrations are toxic to ecosystems and potentially to public health via the accumulation in food chain. Although Sb is poisonous and carcinogenic to humans, the exact mechanisms causing toxicity still remain unclear. Most studies concerning the remediation of soils and aquatic environments contaminated with Sb have evaluated various amendments that reduce Sb bioavailability and toxicity. However, there is no comprehensive review on the biogeochemistry and transformation of Sb related to its remediation. Therefore, the present review summarizes: (1) the sources of Sb and its geochemical distribution and speciation in soils and aquatic environments, (2) the biogeochemical processes that govern Sb mobilization, bioavailability, toxicity in soils and aquatic environments, and possible threats to human and ecosystem health, and (3) the approaches used to remediate Sb-contaminated soils and water and mitigate potential environmental and health risks. Knowledge gaps and future research needs also are discussed. The review presents up-to-date knowledge about the fate of Sb in soils and aquatic environments and contributes to an important insight into the environmental hazards of Sb. The findings from the review should help to develop innovative and appropriate technologies for controlling Sb bioavailability and toxicity and sustainably managing Sb-polluted soils and water, subsequently minimizing its environmental and human health risks.

Total and Leached Arsenic, Mercury and Antimony in the Mining Waste Dumping Area of Abbadia San Salvatore (Mt. Amiata, Central Italy)

Total and leached Arsenic, Mercury and Antimony were determined in the topsoils developed on the mining waste dumping area of Le Lame (Mt. Amiata, central Italy) where the post-processing Hg-rich ore deposits from the mining area of Abbadia San Salvatore were stored. The concentrations of As, Hg and Sb were up to 610, 1910 and 1610 mg kg−1, respectively, while those in the leachates (carried out with CO2-saturated MilliQ water to simulate the meteoric water conditions) were up to 102, 7 and 661 μg·L−1, respectively. Most aqueous solutions were characterized by Hg content <0.1 μg·L−1. This is likely suggesting that the mine wastes (locally named “rosticci”) were possibly resulting from an efficient roasting process that favored either the removal or inertization of Hg operated by the Gould furnaces and located in the southern sector of Le Lame. The highest values of total and leachate mercury were indeed mostly found in the northern portion where the “rosticci”, derived by the less efficient and older Spirek-Cermak furnaces, was accumulated. The saturation index was positive for the great majority of leachate samples in Fe-oxy-hydroxides, e.g., ferrihydrite, hematite, magnetite, goethite, and Al-hydroxides (boehmite and gibbsite). On the other hand, As- and Hg-compounds were shown to be systematically undersaturated, whereas oversaturation in tripuhyte (FeSbO4) and romeite (Ca2Sb2O7) was evidenced. The Eh-pH diagrams for the three chalcophile elements were also constructed and computed and updated according to the recent literature data.

Spatial Variation of Water Chemistry in Aries River Catchment, Western Romania

This study aims to investigate the quality and vulnerability of surface water (Aries River catchment) in order to identify the impact of past mining activities. For this purpose, the pollution and water quality indices, Piper and Durov plots, as well vulnerability modeling maps were used. The obtained results indicate that the water samples were contaminated with As, Fe, Mn, Pb and have relatively high concentrations of SO42−, HCO3−, TDS, Ca, K, Mg and high values for the electrical conductivity. Possible sources of the high content of chemicals could be the natural processes or the inputs of the mine drainage. Generally, according to the pollution indices, which were correlated to high concentrations of heavy metals, especially with Pb, Fe and Mn, the water samples were characterized by heavy metals pollution. The water quality index classified the studied water samples into five different classes of quality, namely: unsuitable for drinking, poor, medium, good and excellent quality. Similarly, medium, high and very high vulnerability classes were observed. The Durov and Piper plots classified the waters into Mg-HCO3− and Ca-Cl− types. The past and present mining activities clearly change the water chemistry and alter the quality of the Aries River, with the water requiring specific treatments before use.

Immobilization persistence of Cu, Cr, Pb, Zn ions by the addition of steel slag in acidic contaminated mine soil

Adding steel slag to the acidic contaminated mine soil can immobilize heavy metal ions, but immobilization persistence of the metal ions needs to be determined. In this study, dynamic column simulation experiments were set up to compare the immobilization persistence of Cu, Cr, Pb and Zn ions in original soil and with the addition of slag, lime or fly ash to the soil during a simulated 36-month of acid rain leaching. After adding slag and lime, the pH, organic matter content and cation exchange capacity of soil were significantly increased. Compared with the original soil, additions of slag and lime to the soil were able to persistently immobilize the metal ions, whereas fly ash additions had little effect. During simulation, the metal ion concentrations in the slag group leaching solution were essentially consistent with Standard IV for groundwater. The metal ions were immobilized to form instable hydroxides and stable fractions following adding slag to soil. The hydroxide could rerelease metal ions by acid rain leaching, part of which were re-immobilized into stable fractions by entering slag lattice and complexing with soil organic matter. Therefore, adding slag to soil can persistently immobilize metal ions for heavy metal-contaminated acidic mine soil.

Potentially toxic metal(loid) distribution and migration in the bottom weathering profile of indigenous zinc smelting slag pile in clastic rock region

Background

There are contaminated by potentially toxic metal(loid)s (PTMs) that the surface soil and the weathering profiles around the indigenous zinc smelting slag piles or smelters in the smelting area. However, few systematic studies are currently focusing on the PTM distribution and migration among the slag and its bottom weathering profile.

Methods

This research determined the concentrations of PTMs and pH values. And we analyzed PTM distribution in the two weathering profiles (slag-covered and slag-absent) with a small horizontal distance in the clastic rock region in the smelting area.

Results

The soil As and Pb contents, respectively, within the 30 and 50 cm depth in the slag-covered section were higher than those in the slag-absent profile. All soil Cd and Zn contents of the slag-covered core were significantly higher than those in the slag-absent weathering section.

Conclusions

Compared with the slag-absent weathering section, some PTMs (i.e., As, Cd, Pb and Zn) in the bottom weathering profile were polluted by these elements in the covered slag in the clastic rock region, and their depths were influenced by the slag to varying degrees. Additionally, with time, some PTMs (especially Cd and Zn) of the slag might finally contaminate the groundwater by leaching and infiltration through its bottom weathering profile in the clastic rock region.

Element transfer by a vapor-gas stream from sulfide mine tailings: from field and laboratory evidence to thermodynamic modeling

Condensates of vapor-gas streams were collected during field and laboratory experiments for the determination of the volatility of chemical elements in sulfide tailings under ambient conditions. The object of research was the Ursk waste heaps (Kemerovo region, Russia). Field experiments were performed on the top of the heap and in neighboring territories; the elements' concentrations in condensates from the top exceed the background values in 2-3 orders of magnitude. To obtain condensates in the laboratory, the waste material was heated to 60 °С. Laboratory condensate-contended high concentrations Ca, Mg, but Fe, Cd, Mo, Sn, Zr, and W were lower by more than 2 orders of magnitude. Also, chemical elements such as Au, Zr, Cs, U, and Tl were determined in the laboratory condensates at elevated temperatures. Also, solid samples were leached with water at the laboratory. A high positive correlation of condensate compositions with compositions of water extracts obtained from parallel samples was established. The most mobile elements transferred in the steam-gas phase are alkaline (Li, Cs, Na, K), alkaline earth (Ca, Sr), chalcophile metals (Hg, Zn, Cu), and metalloids (As, Sb, Se). The numerical experiment of metal transfer forms using thermodynamic modeling methods has been performed, including those with organic ligands.

Waste-to-Energy Process to Recover Dangerous Pollutants in an Environmental Protected Area

The present study aims to extract the polluting material from a lagoon and use it as an alternative fuel in cement industries. To this end, in the methodology will analyze two alternatives for the waste: fuel generation and incineration. The polluting material from the Arganda lagoon has highly calorific value to be used as fuel. Thus, not only are these wastes used, but also an area with potentially hazardous waste is decontaminated. After the extraction, which due to the characteristics of the material is chosen for the novel pumping extraction, and subsequent generation of fuel, the process for using this waste is through the distribution of the created fuel to nine cement plants in Spain, leading to significant environmental benefits. The results of the process shows an energy efficiency of 97% for using the waste as fuel, and a consumed energy of approximately 6000 kWh/t·waste to the process that leads to the desired environmental benefit. The use of waste contributes to the reduction of CO2 emissions and a decrease in the use of fossil fuels.

Geogenic and anthropogenic interactions at a former Sb mine: environmental impacts of As and Sb

Mining activities are acknowledged to introduce contaminants into localised environments and cause wider spread diffuse pollution. The concentration, distribution and fate of arsenic (As) and antimony (Sb) were studied at the former metalliferous Louisa Mine at Glendinning, Scotland. Soils and surface water were sampled and subsequently analysed to map the distribution of contamination and identify pollution sources. The maximum concentrations of As and Sb of 15,490 and 1504.2 mg kg^-1, respectively, were determined in soils associated with the ore processing area and spoil heaps. The fractions of dissolved As and Sb in soils were < 1 and < 5% of total soil content, respectively, confirming findings of previous studies that As and Sb are relatively immobile. Yet, the concentrations of As and Sb released by soils exceeded regulatory limits. Concentrations of As and Sb in surface water in the immediate vicinity of the mine were impacted by a gully discharge, but rapidly diluted. While the concentrations affected by the run-off waters did not exceed EU environmental standards for freshwater, the concentrations of both, As and Sb, sharply increased above the said environmental standards approximately 100 m downstream of the mine site. The unaltered As-to-Sb ratio in water samples suggests a geogenic source. While there is a justifiable concern about the soil pollution caused by the historic mining in the area, the Glenshanna Burn is affected more by indigenous geochemical processes than the derelict mine.

An overview on heavy metal resistant microorganisms for simultaneous treatment of multiple chemical pollutants at co-contaminated sites, and their multipurpose application

Anthropogenic imbalance of chemical pollutants in environment raises serious threat to all life forms. Contaminated sites often possess multiple heavy metals and other types of pollutants. Elimination of chemical pollutants at co-contaminated sites is imperative for the safe ecosystem functions, and simultaneous removal approach is an attractive scheme for their remediation. Different conventional techniques have been applied as concomitant treatment solution but fall short at various parameters. In parallel, use of microorganisms offers an innovative, cost effective and ecofriendly approach for simultaneous treatment of various chemical pollutants. However, microbiostasis due to harmful effects of heavy metals or other contaminants is a serious bottleneck facing remediation practices in co-contaminated sites. But certain microorganisms have unique mechanisms to resist heavy metals, and can act on different noxious wastes. Considering this significant, my review provides information on different heavy metal resistant microorganisms for bioremediation of different chemical pollutants, and other assistance. In this favour, the integrated approach of simultaneous treatment of multiple heavy metals and other environmental contaminants using different heavy metal resistant microorganisms is summarized. Further, the discussion also intends toward the use of heavy metal resistant microorganisms associated with industrial and environmental applications, and healthcare. PREFACE: Simultaneous treatment of multiple chemical pollutants using microorganisms is relatively a new approach. Therefore, this subject was not well received for review before. Also, multipurpose application of heavy metal microorganisms has certainly not considered for review. In this regard, this review attempts to gather information on recent progress on studies on different heavy metal resistant microorganisms for their potential of treatment of co-contaminated sites, and multipurpose application.

Combination of compositional data analysis and machine learning approaches to identify sources and geochemical associations of potentially toxic elements in soil and assess the associated human health risk in a mining city

Mining activities change the chemical composition of the environment and have negative reflection on people's health and there is no single measure to deal with adverse consequences of mining activities, as each case is specific and needs to be understood and mitigated in a unique way. In this study, the combination of compositional data analysis (CoDA), k-means algorithm, hierarchical cluster analysis applied to reveal the geochemical associations of potentially toxic elements (PTE) in soil of Alaverdi city (Armenia) (Ti, Fe, Ba, Mn, Co, V, Pb, Zn, Cu, Cr, Mo, As). Additionally, to assess PTE-induced health risk, two commonly used approaches were used. The obtained results show that the combination of CoDA and machine learning algorithms allow to identify and describe three geochemical associations of the studied elements: the natural, manmade and hybrid. Moreover, the revealed geochemical associations were linked to the natural pattern of distribution of the element concentrations including the influence of the natural mineralization of the parent rocks, as well as the emission from the copper smelter and urban management related activities. The health risk assessment using the US EPA method demonstrated that the observed contents of studied elements are posing a non-carcinogenic risk to children in the entire territory of the city. In the case of adults, the non-carcinogenic risk was identified in areas situated close to the copper smelter. The Summary pollution index (Zc) values were in line with the results of the US EPA method and indicated that the main residential part of the city was under the hazardous pollution level suggesting the possibility of increase in the overall incidence of diseases among frequently ill individuals, children with chronic diseases and functional disorders of vascular system. The obtained results indicated the need for further in-depth studies with special focus on the synergic effect of PTE.

Assessment of Geotourism Values and Ecological Status of Mines in Kopaonik Mountain (Serbia)

Abandoned mines can pose a major environmental hazard. At the beginning of the 21st century, significant steps were taken all around the world in order to protect these historically valuable complexes, and the mining heritage was recognized as a potential for the development of alternative tourism. This exploration covers mines in the Kopaonik Mountain area. Mining on this mountain began in ancient times. It has developed throughout history, and today only one mine is active. Three abandoned (Gvozdac, Suvo Rudište and Raičeva Gora) and one active mine (Belo Brdo-Zaplanina) are the subject of research. The basic aim of the research is twofold. The estimation of geo-tourist values was performed using the Geosite Assessment Model (GAM), and the ecological status assessment WAS performed according to the standard model based on negative and positive values. Based on the applied methods, it was concluded that mines (geosites) have a high level of natural characteristics, and that differences between geosites are evident in tourist values. The reason for this is insufficient tourist affirmation and the insufficient availability of tourist infrastructure. With the ecological status, positive values were observed on the geosites, which also differ from one (Raičeva Gora) to 15 points (Gvozdac). In the end, the results obtained are of great scientific importance, and their direct application is in the development of the Tourism Development Strategy in the Kopaonik area.

Influence of ferrous-metal production on mercury contamination and fractionation in farmland soil around five typical iron and steel enterprises of Tangshan, China

Iron and steel production is one of the main anthropogenic sources of mercury (Hg) emission and release. Oxidized and particulate Hg discharged from iron and steel enterprises deposit into the surrounding soil, which accumulate and introduce environmental risks. Therefore, it is important to assess Hg pollution in the soil surrounding iron and steel enterprises. In this study, the Hg pollution, Hg distribution from steel plants and Hg fractionation in farmland soil around five typical steel plants were analysed in Tangshan of China. The Hg pollution indexes (Pi) of more than 90% soil samples were greater than 3 by the single factor pollution index method, which showed that most soil samples around the five steel plants were strongly contaminated by Hg. The Hg contents in soil increased first and then decreased, and the maximum content presented at 250-300 m away from the boundary of the steel plants. The order of Hg fraction proportion in the soil samples was extractable (35%-43%) > volatile (24%-36%) > residual (10%-26%) > reducible (0-15%) > oxidizable (0-12%). The distribution of Hg fraction in farmland soil had no regular trend with the distance from the steel plants. The volatile Hg and extractable Hg were dominant in farmland soil, and their combined proportion was greater than 60%. These two fractions of Hg are at risk of re-volatilization into the atmosphere or potential absorption by plants.

A 200 km-long mercury contamination of the Paglia and Tiber floodplain: Monitoring results and implications for environmental management

This paper reports the results of a joint project carried out by three regional environmental agencies of Italy to evaluate long-range mercury (Hg) transport from the abandoned Mt. Amiata Hg district in southern Tuscany (the third largest worldwide site for Hg production) to the fluvial ecosystems of the Paglia and Tiber rivers. Most of the work focused on stream sediments, surface waters and soils. A preliminary survey of Hg⁰ content in air was also conducted. Data obtained by public health authorities on Hg in vegetables and fish were also included. The highest Hg concentrations (up to thousands of μg/g Hg) were observed in stream sediments and soils directly impacted by Hg mine runoff. Although progressive Hg dilution was observed from north to south along the river, sediments and soils show anomalous Hg levels for over 200 km downstream of Mt. Amiata, testifying to an extreme case of long-range Hg contamination. A pervasive redistribution of Hg is observed in all sediment compartments. Presumably, the width of the impacted fluvial corridor corresponds to the entire alluvial plains of the rivers. The floodplains can be considered new sources for downstream Hg redistribution, especially during large flood events. On the other hand, results from water, air, and vegetable sampling indicate low potential for human exposure to Hg. The extent and distribution of the contamination make remediation not viable. Therefore, people and human activities must coexist with such an anomaly. On the technical side, the most urgent action to be taken is a better definition of the exact extent of the contaminated area. On the management side, it is necessary to identify which public institution(s) can best deal with such a widespread phenomenon. According to the precautionary principle, the impact of the contamination on human activities in the affected areas should be considered.

Continuous impact of mining activities on soil heavy metals levels and human health

Soils samples collected during different geochemical surveys of the city of Kajaran located near the biggest Cu-Mo mining area in Armenia were subjected to the multivariate geostatistical analysis and geochemical mapping in order to reveal soil heavy metals spatial distribution pattern and assess human health risk level under continuous impact of mining activities. In addition, human health risk assessment was done for the contents of Pb, Cu, Zn, Co, Mo, Mn, Ti, and Fe. The results of Principal Component Analysis and Cluster Analysis verify each other and were also complemented by the spatial distribution features of studied heavy metals indicating that two groups of elements have been generated. The first anthropogenically predominated group includes the main industrial elements Mo and Cu, and their accessories Pb and Zn while Ti, Mn, Fe and Co with the naturally predominant contents were observed in the second group. Moreover, the study reveals that the superposition of geogenic and anthropogenic components lead to the alteration of the shapes of areas with the high natural contents of heavy metals and formation of polluted areas with the intensive anomalies of elements. Health risk assessment showed that Mo was the only studied element which poses a non-carcinogenic risk to adult and children's health in some sampling sites during the whole period of investigations. Moreover, in all studied locations multi-elemental non-carcinogenic risk to children health from all studied heavy metals were detected. Special attention was given to the soils of kindergarten territories, and the results indicated that Hazard Index in kindergartens was >1 indicating an adverse health effect to children. The results obtained can serve as a basis for the development and implementation of risks reduction measures and systematic monitoring program planning.