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This document is a summary of a special issue on "Heavy Metal Toxicity: Environmental and Human Health Risk Assessment." The issue includes fourteen papers that cover various aspects of heavy metal toxicity, such as metal pollution, bioindicators, environmental indicators, phytoremediation, epigenetics, and detoxification therapies. The papers discuss topics such as the monitoring of particulate matter using olive pollen as a bioindicator, the impact of heavy metals on fish and medicinal plants, the presence of toxic elements in sediment and water, lead contamination in soils and sediments, the effectiveness of substances in reducing heavy metal content in soil, the potential sources and concentration of heavy metals in sediments and flamingo tissues, the cellular effects of silver nanoparticle suspensions, the morphological and molecular alterations induced by lead in fish embryos and larvae, heavy metal concentrations in wild brown trout, microbial-based heavy metal bioremediation techniques, and the uses, toxicity, and detoxification therapies of arsenic and thallium. The special issue concludes by mentioning the possibility of further exploration and research in this field. [Extracted from the article]

The generation of acid mine drainage (AMD) characterized by high acidity and elevated levels of toxic metals primarily results from the oxidation and dissolution of sulfide minerals facilitated by microbial catalysis. Although there has been significant research on microbial diversity and community composition in AMD, as well as the relationship between microbes and heavy metals, there remains a gap in understanding the microbial community structure in uranium-enriched AMD sites. In this paper, water samples with varying levels of uranium pollution were collected from an abandoned stone coal mine in Jiangxi Province, China during summer and winter, respectively. Geochemical and high-throughput sequencing analyses were conducted to characterize spatiotemporal variations in bacterial diversity and community composition along pollution groups. The results indicated that uranium was predominantly concentrated in the AMD of new pits with strong acid production capacity, reaching a peak concentration of 9,370 µg/L. This was accompanied by elevated acidity and concentrations of iron and total phosphorus, which were identified as significant drivers shaping the composition of bacterial communities, rather than fluctuations in seasonal conditions. In an extremely polluted environment (pH < 3), bacterial diversity was lowest, with a predominant presence of acidophilic iron-oxidizing bacteria (such as Ferrovum), and a portion of acidophilic heterotrophic bacteria synergistically coexisting. As pollution levels decreased, the microbial community gradually evolved to cohabitation of various pH-neutral heterotrophic species, ultimately reverting back to background level. The pH was the dominant factor determining biogeochemical release of uranium in AMD. Acidophilic and uranium-tolerant bacteria, including Ferrovum, Leptospirillum, Acidiphilium, and Metallibacterium, were identified as playing key roles in this process through mechanisms such as enhancing acid production rate and facilitating organic matter biodegradation. [ABSTRACT FROM AUTHOR]

This paper studied the characteristics of the carbon emission of an industrial wastewater treatment plant (IWWTP) and a domestic WWTP (DWWTP) located in a high-tech industrial park of Shaanxi Province, China. The results showed that the total carbon emissions of the IWWTP and DWWTP were 10.13 kg/t and 1.84 kg/t in 2020, respectively. Indirect carbon emissions play a dominant role in the total carbon emission of the IWWTP, which accounts for about 97.6% of the total amount. The direct carbon emissions of greenhouse gases (e.g., CH4, N2O) account for about 62% of the total carbon emissions in the DWWTP, followed by the indirect carbon emissions generated by electricity consumption (31.06%) and chemical consumption (6.94%). Additionally, the centralized recycling and re-utilization of the wastewater could achieve 1.06 kg/t and 1.16 kg/t of carbon emission reduction in the IWWTP and DWWTP, respectively, while the carbon emissions of the DWWTP are inversely proportional to the treatment capacity. Therefore, it is of great value to collect and utilize intensively the recycled water to achieve the goal of regional carbon emission reduction and carbon neutralization of WWTPs in industrial parks. [ABSTRACT FROM AUTHOR]

The textile dyeing and manufacturing industry is the major producer of significant amounts of wastewater that contain persistent substances such as azo dyes that require adequate remediation measures. Far ultraviolet at 222 nm light may provide an advantage for contaminants degradation as compared to conventional UV sources (254 nm). In this paper, the degradation of reactive black 5 (RB5) in artificial wastewater has been performed using a 222 nm Kr/Cl2 excimer source under direct photolysis and an advanced oxidation process using TiO2/H2O2. The solution pH, catalyst concentration, 222 nm intensity, initial concentration of dye, and addition of H2O2 influence the degradation rate constant. The molar absorption coefficient, quantum yield of RB5 at 222 nm and the electrical energy per order (EEO) from different treatment methods have been reported. RB5 shows 1.26 times higher molar absorption at 222 nm than at 254 nm. The EEO for excimer-222/H2O2 (∼ 13 kWh/m3) is five times lower than that of the excimer-222/TiO2 process, which makes the process energy efficient. The degradation of wastewater has been carried out at three distinct pH values (2, 6, and 10), and the pH level of 10 exhibited the highest degree of degradation. The degradation rate in the alkaline medium is 8.27 and 2.05 times higher than in the acidic or ambient medium. Since textile effluent is highly alkaline, this result is significant, as no neutralization of the wastewater is required, and direct treatment is possible. A possible degradation pathway has been established based on Fourier transform infrared spectroscopy (FTIR) and high resolution mass spectroscopy (HRMS) analysis. The phytotoxicity of the treated wastewater has also been evaluated for its suitability for reuse in agriculture. The study reveals that the excimer-222/H2O2 treated wastewater significantly enhanced the germination percentage of Raphanus sativus seed (97%) compared to dye wastewater-grown seeds (75%). This work offers crucial information for future studies on the direct and indirect photolysis of azo dyes, as well as insight into the process of RB5 degradation under Kr/Cl2 excimer radiation. [ABSTRACT FROM AUTHOR]

This paper evaluates an experimental wetland as part of a pilot soil reclamation project in a mining area. The wetland was constructed using materials of mining origin from the area; most reactive materials of acid pH were stabilised using limestone filler. The study selected macrophytes that are tolerant to potentially toxic elements (PTEs) and resistant to salinity, namely Phragmites australis, Juncus effusus, and Iris pseudacorus. These macrophytes were then placed in pots containing substrates composed of different mixtures of topsoil, peat, and mining waste (black or yellow sand). A thorough analysis of the physicochemical and mineralogical characteristics of the materials included studies of PTE mobilisation. This study emphasises the significance of the rhizosphere in directing the transfer of PTEs to the plant and the correlation between the substrate and the development of plant defence mechanisms, such as the formation of Fe-plates. Scanning electron microscopy was used to highlight these aspects and validate the results of the analytical determinations. These wetlands can be proposed as a phytoremediation strategy for areas affected by mining and maritime influence. They are easy to construct and remain stable, providing important ecosystem services such as the natural attenuation of acid mine drainage, support for vegetation development and fauna, and a clean ecosystem. [ABSTRACT FROM AUTHOR]

However, while AI-generated text can undoubtedly be beneficial in expediting the writing process, caution must be exercised to ensure that the final output reflects the expertise and intent of the author. Researchers must be able to understand how AI models arrive at their conclusions and be aware of any limitations or potential biases in the algorithms. Before addressing the topic of AI, we need to note that this issue contains fewer papers than any issue we have published in over a decade, and it contains I every i paper that was ready for publication. [Extracted from the article]

Opencast coal mining produces trash of soil and rock containing various minerals, that are usually dumped nearby the abandoned sites which causes severe environmental concern including the production of acid mine drainage (AMD) through oxidation pyrite minerals. The current study entailed assessing the potential production of AMD from an opencast coal mining region in Northeast part of India. In order to have a comprehensive overview of the AMD problem in Makum coalfield, the physico-chemical, geochemical, and petrological characteristics of the coal and overburden (OB) samples collected from the Makum coalfield (Northeast India) were thoroughly investigated. The maceral compositions reveal that coal features all three groups of macerals (liptinite, vitrinite, and inertinite), with a high concentration of liptinite indicating the coal of perhydrous, thereby rendering it more reactive. Pyrite (FeS2) oxidation kinetics were studied by conducting the aqueous leaching experiments of coal and (OB) samples to interpret the chemical weathering under controlled laboratory conditions of various temperature and time periods, and to replicate the actual mine site leaching. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) was operated to detect the disposal of some precarious elements from coal and OB samples to the leachates during our controlled leaching experiment. The Rare earth element (REE) enrichment in the samples shows the anthropogenic incorporation of the REE in the coal and OB. These experiments reveal the change in conductivity, acid producing tendency, total dissolved solid(TDS), total Iron(Fe) and dissolved Sulfate(SO42−) ions on progress of the leaching experiments. Moreover, the discharge of FeS2 via atmospheric oxidation in laboratory condition undergoes a significant growth with the rise of temperature of the reaction systems in the environment and follows pseudo first order kinetics. A bio-remediative strategies is also reported in this paper to mitigate AMD water by employing size-segregated powdered limestone and water hyacinth plant in an indigenously developed site-specific prototype station. Apart from neutralisation of AMD water, this eco-friendly AMD remediation strategy demonstrates a reduction in PHEs concentrations in the treated AMD water. [ABSTRACT FROM AUTHOR]

This paper aimed to analyse the potato cultivar's response to physiological, biochemical performance, yield parameters and soil physiochemical properties when subjected to quicklime (un)treated acid mine drainage (AMD) irrigation. A randomized design experiment was conducted with five water treatment levels: TW1; TW2; TW3; TW4 to TW5 replicated four times. The results showed that the quicklime treatment increased the pH of the AMD water, reduced the concentration of EC, NO3−, SO42− and ameliorated heavy metals. However, unsafe levels of heavy metals above the maximum permissible (WHO/FAO) levels were found in Pb, Mg and Mo for water (TW4 and TW5), while As, Cd and Cr for soils (ST4 and ST5) respectively. For potato tubers (TT4 and TT5) concentrations of As, Cd, Cr, and Pb were above the maximum levels. Stomatal conductance, chlorophyll content and yield parameters responded positively by increasing significantly on TW4 and TW5 treatments, but negatively (reduced) towards TW2 and TW3 treatments. A higher bioaccumulation factor was obtained for Zn ˃ Cu ˃ Mg ˃ Pb ˃ Mn, which was an indication of the contamination status of soil, with Zn being more concentrated than other metals. The findings indicate that quicklime-treated AMD is usable for potato irrigation with regular monitoring of heavy metal levels and strict observation of water reuse protocols. The use of this large source of ameliorated (AMD) water will go a long way in improving food security in South Africa and/or in countries where agriculture production is around mining areas. [ABSTRACT FROM AUTHOR]

The construction industry is recognized for its high consumption of natural resources, resulting in significant environmental impacts. Given this reality, it is essential to seek new methods and solutions that minimize the impact of this activity on the environment. An innovative approach consists of using pigments derived from acid mine drainage (AMD) as a sustainable alternative in the production of mortar for decorative façade cladding. In this context, the main objective of this paper was to evaluate the physical/mechanical properties of decorative mortars developed by partially replacing natural sand with pigment from acid mine drainage. Initially, the pigment (yellow) was produced, characterized, and compared with a commercial pigment. Sequentially, decorative mortars were developed with different pigment concentrations (0%, 2%, 4%, and 6%). The mortars were subjected to compressive strength, flexural tensile strength, shrinkage, loss of mass, and colorimetry tests. The results showed that compressive strength, flexural tensile strength, weight loss, and dimensional variation were significantly affected by the partial addition of pigment to replace natural aggregate. In other words, there was a decrease in strength and an increase in mass loss and expansion of the mortars. However, the main factor influencing these variables was the greater amount of water added in the higher substitution cases. The addition of water was necessary to keep the consistency constant. A possible solution to maintain the same amount of water and avoid negative effects on the mortar properties would be to use additives in the mortar formulation in future work. Therefore, this research contributes to the search for more sustainable solutions in civil construction, exploring the use of pigments from AMD as a viable alternative to reduce the environmental impacts associated with this industry. [ABSTRACT FROM AUTHOR]

Mining waste is an obvious source of environmental pollution due to the presence of heavy metals, which can contaminate soils, water resources, sediments, air, and people living nearby. The F-(Ba-Pb-Zn) deposit of Hammam Zriba located in northeast Tunisia, 8 km southeast of Zaghouan was intensively exploited from 1970 to 1992. More than 250,000 m3 of flotation tailings were produced and stored in the open air in three dumps without any measure of environmental protection. Thus, in this paper, mineralogical and chemical characterization, especially the sulfide and carbonate phases, were carried out to evaluate the potential for acid mining drainage (AMD) and metal leaching (ML). Conventional analytical methods (XRD, XRF, SEM) have revealed that this mining waste contains on average 34.8% barite–celestine series, 26.6% calcite, 23% quartz, 6.3% anglesite, 4.8% fluorite, 2.1% pyrite, and 0.4% sphalerite. The content of sulfides is less important. The tailing leaching tests (AFNOR NFX 31-210 standard) did not generate acidic leachate (pH: 8.3). The acidity produced by sulfide oxidation was neutralized by calcite present in abundance. Furthermore, the leaching tests yielded leachates with high concentrations of heavy metals, above the authorized thresholds. This high mobilization rate in potential toxic elements (PTE) represents a contamination risk for the environment. [ABSTRACT FROM AUTHOR]

How to efficiently deal with waste acids and bases produced by industry has constantly been a tough question for scientists and engineers. Such acid–base wastewaters are normally treated by mixing to give neutral products (i.e., water and salts) and heat which is hard to collect and reuse. Therefore, there is a need for innovative approaches with high efficiencies and high-value added products. Here, we report an air/metal hydride battery with the function of both treating acid–base wastewaters and gathering the waste heat energy in the form of electricity. Remarkably, the proposed battery could exhibit a high coulombic efficiency of up to ca. 94%, along with an effective reduction in the acidity/alkalinity of waste acids/bases and a decent amount of electricity. The proposed battery device also demonstrates a stable operation in semi-flow mode over a two-day timescale, showcasing its potential scalability and long-term stability. Moreover, life cycle assessment results indicate that electricity retrieved from the treatment process is a key contributor to reducing environmental impacts. This work offers alternative opportunities for accelerating the transition to a waste acid–base circular economy. [ABSTRACT FROM AUTHOR]

Verrucomicrobia are a group of microorganisms that have been proposed to be deeply rooted in the Tree of Life. Some are methanotrophs that oxidize the potent greenhouse gas methane and are thus important in decreasing atmospheric concentrations of the gas, potentially ameliorating climate change. They are widespread in various environments including soil and fresh or marine waters. Recently, a clade of extremely acidophilic Verrucomicrobia, flourishing at pH < 3, were described from high-temperature geothermal ecosystems. This novel group could be of interest for studies about the emergence of life on Earth and to astrobiologists as homologs for possible extraterrestrial life. In this paper, we describe predicted mechanisms for survival of this clade at low pH and suggest its possible evolutionary trajectory from an inferred neutrophilic ancestor. Extreme acidophiles are defined as organisms that thrive in extremely low pH environments (≤pH 3). Many are polyextremophiles facing high temperatures and high salt as well as low pH. They are important to study for both providing fundamental insights into biological mechanisms of survival and evolution in such extreme environments and for understanding their roles in biotechnological applications such as industrial mineral recovery (bioleaching) and mitigation of acid mine drainage. They are also, potentially, a rich source of novel genes and pathways for the genetic engineering of microbial strains. Acidophiles of the Verrucomicrobia phylum are unique as they are the only known aerobic methanotrophs that can grow optimally under acidic (pH 2–3) and moderately thermophilic conditions (50–60◦C). Three moderately thermophilic genera, namely Methylacidiphilum, Methylacidimicrobium, and Ca. Methylacidithermus, have been described in geothermal environments. Most of the investigations of these organisms have focused on their methane oxidizing capabilities (methanotrophy) and use of lanthanides as a protein cofactor, with no extensive study that sheds light on the mechanisms that they use to flourish at extremely low pH. In this paper, we extend the phylogenetic description of this group of acidophiles using whole genome information and we identify several mechanisms, potentially involved in acid resistance, including “first line of defense” mechanisms that impede the entry of protons into the cell. These include the presence of membrane-associated hopanoids, multiple copies of the outer membrane protein (Slp), and inner membrane potassium channels (kup, kdp) that generate a reversed membrane potential repelling the intrusion of protons. Acidophilic Verrucomicrobia also display a wide array of proteins potentially involved in the “second line of defense” where protons that evaded the first line of defense and entered the cell are expelled or neutralized, such as the glutamate decarboxylation (gadAB) and phosphate-uptake systems. An exclusive N-type ATPase F0-F1 was identified only in acidophiles of Verrucomicrobia and is predicted to be a specific adaptation in these organisms. Phylogenetic analyses suggest that many predicted mechanisms are evolutionarily conserved and most likely entered the acidophilic lineage of Verrucomicrobia by vertical descent from a common ancestor. However, it is likely that some defense mechanisms such as gadA and kup entered the acidophilic Verrucomicrobia lineage by horizontal gene transfer. [ABSTRACT FROM AUTHOR]

Limited by mining technology, mineral exploitation can produce large amounts of tailings. Heavy summer rainfall or seasonal freeze-thaw can lead to physical and chemical modification of tailing material in mountainous areas, resulting in fluidized tailings flow and severe disaster losses. Therefore, aiming at the problem of tailings fluidization catastrophe, this paper tried to reveal the rheological mechanism of tailings fluidization transformation by combining rheological tests and theoretical analysis. The results show that the yield stress increases with decreasing temperature, and when the density of debris flow (ρ) is more than 1.9 g/cm3, this behavior becomes more pronounced as the density increases. The storage modulus decreases by at least two orders of magnitude at the solid-fluid transition under amplitude test sweep. Storage and loss modulus in the linear viscoelastic range and yield stress have an exponential growth relationship with sediment concentration. In addition, a stress constitutive relation and a new exponential law describing the evolution of yield stress required for solid-liquid transformation were proposed, and the relationship is further strengthened through a comprehensive analysis of existing results, which expands the evaluation application of the rheological characteristics of tailings flow. This paper provides a new insight into the rheological properties of tailing and how they occur through solid-liquid transition under different environments, which is beneficial to geological hazard prevention and the ecological remediation of the mining area. [ABSTRACT FROM AUTHOR]

Acid mine drainage and soil erosion are significant problems in the coal mining area. It affects the water quality and soil quality, henceforth affecting plant growth and most aquatic life. During the last two decades, coal mining areas were increased by 194 hectares in Makum coalfield (Assam), which led to an increase in acid mine drainage and soil loss. In this paper, the water chemistry of water samples was analyzed, and annual soil loss near the area of Makum coalfield was calculated to investigate the most affected region by Acid Mine Drainage (AMD) and soil erosion. The Watershed delineation, slope angle, elevation contour map, and drainage system of 57 km2 of the study area were developed by ArcGIS Pro. The Universal Soil Loss Equation was used to estimate the amount of annual soil loss. The USLE parameter was assessed using a Digital Elevation Model with a 30-meter X 30-meter resolution. The result indicates that the quality of drainage near the mines was highly acidic. Also, compared to the area near the riverside, the proximity of mines is more affected by soil erosion and needs improvement. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) poses serious consequences for human health and ecosystems. Novel strategies for its treatment involve the use of wastes. This paper evaluates the remediation potential of wastes from urban, mining and agro-industrial activities to address acidity and high concentrations of potentially toxic elements (PTE) in AMD. Samples of these waste products were spiked with an artificially prepared AMD, then pH, electrical conductivity (EC), and PTE concentrations in the leachates were measured. The artificial AMD obtained through oxidation of Aznalcóllar's tailing showed an ultra-acid character (pH − 2.89 ± 0.03) and extreme high electrical conductivity (EC − 3.76 ± 0.14 dS m−1). Moreover, most PTE were above maximum regulatory levels in natural and irrigation waters. Wastes studied had a very high acid neutralising capacity, as well as a strong capacity to immobilise PTE. Inorganic wastes, together with vermicompost from pruning, reduced most PTE concentrations by over 95%, while organic wastes retained between 50 and 95%. Thus, a wide range of urban, mining, and agro-industrial wastes have a high potential to be used in the treatment of AMD. This study provides valuable input for the development of new eco-technologies based on the combination of wastes (eg. Technosols, permeable reactive barriers) to remediate degraded environments. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) is a legacy left behind by abandoned and active mines that affects all environmental media. Contamination of water resources by AMD presents significant challenges to aquatic ecosystem stability and on the abundance and diversity of aquatic species. Aquatic organisms react and are affected differently by these conditions. Several studies have reported on how AMD affects aquatic organisms with most of these studies focusing on a specific group of organisms or characteristic of the water. This review paper presents a holistic view on how aquatic organisms cope with, and are affected by the high acidity, high heavy metals content and precipitation of oxides of iron and aluminium which are characteristic of AMD contaminated freshwater ecosystems. Mechanisms of tolerance and the effects of high acidity, high heavy metals content, and precipitates of oxides of iron and aluminium on diatoms, algae, fish, and amphibians are discussed. The paper concludes by discussing the implications of AMD contamination of aquatic environments on the United Nations Sustainable Development Goals (SDGs) and recommendations on possible future prospects. [ABSTRACT FROM AUTHOR]

One method to accelerate carbon sequestration within mine tailings from remote mines involves the injection of diesel generator exhaust into dry stack tailings. The techno-economic feasibility of this approach heavily depends on understanding the flow characteristics inside the perforated injection pipes embedded within the tailings. Two distinctive yet dynamically coupled transport phenomena were identified and evaluated: (i) gas transport inside the pipe and (ii) gas injection into the porous body of the tailings. This paper presents two models to investigate these transport phenomena, a three-dimensional (3D) and a one-plus-one-dimensional (1 + 1)D model. An experimental investigation of the pressure profile through the injection pipe was carried out to validate the models at the experimental scale. To apply the (1 + 1)D model to larger scales, the results were compared with those of the 3D model, as the (1 + 1)D model required significantly less computational resources and time. To include the effect of the perforations in the pipe on the pressure profile of the (1 + 1)D model, an analytical fluid velocity profile was developed in relation to geometric and physical parameters. The performance of the (1 + 1)D model with an impact factor was then evaluated against the 3D model results for the inlet pressure, pressure profile and gas outflow distribution under various conditions than those investigated experimentally. The developed (1 + 1)D model can be used to design an energy-efficient approach for large-scale implementation with a wide range of desired operating parameters. [ABSTRACT FROM AUTHOR]

Recently, China unveiled "The Implementation Plan for the National Ecological Civilization Zone", which recognizes ecosystems as a community of life and fosters such things as environmental restoration, ecological restoration, and watershed management. In addition, this section explores the environmental state and heavy metal contamination in the Beijing-Tianjin-Hebei region, North China; (3) The final section, including 1 research article and 2 review papers, highlights the aspects of environmental mechanisms and application technologies for metal-contaminated sites. [Extracted from the article]

This paper investigates the intricate interplay between carbon emissions and foreign direct investment within the context of Brazil, Russia, India, China, and South Africa (BRICS) for the period spanning 2000 to 2022. In our comprehensive analysis, we incorporate ecological footprint, renewable energy, globalization, and technological innovations as exogenous variables. Employing a system of simultaneous equations across the BRICS panel, we aim to fully elucidate the proposed relationships. Our empirical findings underscore the following key insights: foreign direct investment, technological innovations, and the adoption of renewable energy sources significantly contribute to the mitigation of carbon emissions in these selected nations. However, it is essential to note that ecological footprints exhibit a positive association with carbon emissions, raising concerns on two fronts: escalating environmental degradation and increased land pressure, both of which contribute to rising ecological footprints in BRICS countries. Additionally, our analysis reveals that foreign direct investment is influenced by its capacity to reduce carbon emissions and bolster renewable energy adoption, while globalization amplifies investment trends within the BRICS nations. To address the environmental repercussions of mining activities, it is imperative to implement stringent control and regulation measures, given their potential adverse impacts, including soil pollution, acid mine drainage, erosion, biodiversity loss, excessive water resource consumption, and wastewater disposal challenges. Nevertheless, proactive steps such as recycling mining waste, adopting environmentally friendly mining equipment, combatting illegal mining, and enhancing overall mining sustainability offer promising avenues to mitigate the environmental footprint of mining operations. [ABSTRACT FROM AUTHOR]

Low-power and smart sensing systems for iron detection are necessary for in situ monitoring of water quality. Here, a potentiometric Fe2+-selective electrode (ISE) was fabricated based on cyanomethyl N-methyl-N-phenyl dithiocarbamate for the first time as an ionophore. Under optimal conditions, the ISE showed a Nernstian slope of 29.76 ± 0.6 mV per decade for Fe2+ ions over a wide concentration range from 1.0 × 10−1 to 1.0 × 10−5 M with a lower detection limit (LOD) of 1.0 × 10−6 M. The ISE interference of various cations on the potentiometric response was also investigated. The ISE had a response time less than 3 s and the lifetime was two months. Also, an automated, long-range (LoRa), wireless enabled sampling microfluidic device powered with a solar panel as an autonomous power source was developed for a continuous sampling and sensing process. The sensing platform was employed in the determination of Fe2+ in acid mine drainage and spiked water samples with an average recovery of 100.7%. This simple, inexpensive (below $350), portable sensing platform will allow for rapid real-time monitoring of ground-, drinking-, and industrial waters contaminated with iron. [ABSTRACT FROM AUTHOR]

• A review with over 300 references on the utilization of challenging ashes. • Metal and phosphorus recovery from different ashes was addressed. • The key beneficial properties of biomass and MSW ashes were identified. In line with the objectives of the circular economy, the conversion of waste streams to useful and valuable side streams is a central goal. Ash represents one of the main industrial side-products, and using ashes in other than the present landfilling applications is, therefore, a high priority. This paper reviews the properties and utilization of ashes of different biomass power plants and waste incinerations, with a focus on the past decade. Possibilities for ash utilization are of uttermost importance in terms of circular economy and disposal of landfills. However, considering its applicability, ash originating from the heat treatment of chemically complex fuels, such as biomass and waste poses several challenges such as high heavy metal content and the presence of toxic and/or corrosive species. Furthermore, the physical properties of the ash might limit its usability. Nevertheless, numerous studies addressing the utilization possibilities of challenging ash in various applications have been carried out over the past decade. This review, with over 300 references, surveys the field of research, focusing on the utilization of biomass and municipal solid waste (MSW) ashes. Also, metal and phosphorus recovery from different ashes is addressed. It can be concluded that the key beneficial properties of the ash types addressed in this review are based on their i) alkaline nature suitable for neutralization reactions, ii) high adsorption capabilities to be used in CO 2 capture and waste treatment, and iii) large surface area and appropriate chemical composition for the catalyst industry. Especially, ashes rich in Al 2 O 3 and SiO 2 have proven to be promising alternative catalysts in various industrial processes and as precursors for synthetic zeolites. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) resulting from metal sulfide mining activities can lead to contamination by potentially toxic elements (PTEs) primarily concentrated around the mining area and gradually spreading outward. However, ecological risks do not correspond directly to PTE concentrations, making it challenging to effectively manage the mining environment and accurately prevent potential ecological impacts. In this paper, we analyzed Cd levels in sediments, soils, and corresponding rice grains sampled from four villages near Dabaoshan Mine of Guangdong, China, in 2017. Our results reveal that Cd is the most prominent pollutant element, exhibiting significant enrichment and spatial heterogeneity in both soil and sediments and higher accumulation levels in rice grains compared to other PTEs. Cd concentrations in soil decrease from the tailings pond to the river terrace, with a slight increase after Taiping River joins and flows into the alluvial plain. However, the concentrations in sediments show the opposite trend. The bioconcentration factor (BCF) for Cd in agricultural soil from the river terrace is lower than that from the alluvial plain and the degree of exceeding the maximum permit level (MPL) of Cd in rice grains increases along the river. Mineral transformation and topography are important factors in controlling the geochemical behavior of PTEs. Remediation efforts alter the physicochemical properties of the river, resulting in the release of PTEs during schwertmannite transformation followed by their adsorption by clay minerals. Furthermore, the random forest (RF) analysis highlights that the bioavailability and potential ecological risk of Cd in soils are governed by the occurrence form of Cd in different topographies, mainly controlled by TFe2O3, Mn, and CaO in the river terrace and CaO, Al2O3/SiO2, and Mn in the alluvial plain. Therefore, considering the impact of topography on mineral compositions, physicochemical properties, and occurrence form of PTEs in soil and sediments is essential for assessing ecological risk in mining areas. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) is an environmental problem commonly found in mining area. This paper collectively investigated the physicochemical parameters in AMD, and the speciation of heavy metals in the sediment and the associated risk of their re-mobilization in the Shirenzhang mine site. Results indicated that the aquatic systems suffered a combined pollution of heavy metals As, Zn, Cu, and Fe. The secondary Fe minerals in the sediments were capable of immobilizing the heavy metals and the immobilization affinity of minerals to As was stronger than that to Zn, Cu, and Cd. At pH<3, the well crystalline minerals including jarosite and ferroarsenite were detected in the sediments, and the heavy metals were mainly presented in the crystalline iron oxide-bound phase and the residual phase. The stability of heavy metals was relative high. At pH>3, however the poor crystalline iron oxyhydroxide including schwertmannite and β - Fe(OOH) were the dominant secondary minerals. And the heavy metals in the sediments were mainly presented in the surface-adsorbed phase and the poor crystalline iron oxide-bound phase, which led to a low stability of the heavy metals. In addition, the relative abundance of iron reducing bacteria was high in the sediments at pH>3, which might induce the transformation of the secondary minerals and the associated mobilization of heavy metals. These results provided important insights into the geochemical behavior of heavy metals in AMD environments. [ABSTRACT FROM AUTHOR]

This paper investigates the occurrence of natural attenuation in sediments from a water reservoir impacted by metals and radionuclides resulting from acid mine drainage. The chemical and radiochemical characterization indicated the enrichment of radionuclides (238U and 226Ra) and metals (Zn) in the sediments. The isotopic deviation δ34S (− 1.3 to − 17.4‰) and high contents of Acid Volatile Sulfide (2.34 to 5.71 g kg−1) indicated the occurrence of natural attenuation all through the reservoir, which contributes to the chemical stabilization of the contaminants. [ABSTRACT FROM AUTHOR]

Studies have indicated the potential of mixtures of silty soil and sludge produced by active treatment of acid mine drainage for use in covers with capillary barrier effects for mine site reclamation. Very high water contents of sludge in the settling pond could negatively affect the required hydrogeotechnical properties of soil sludge mixtures with high sludge contents. The challenge is then to determine the optimum wet sludge content of soil-sludge mixtures with air entry values (AEV) and/or saturated hydraulic conductivity (ksat) required for use in mine site reclamation covers. This paper presents a method to determine the optimum wet sludge content βopt for obtaining the maximum dry density of compacted soil-sludge mixtures. Two types of soil (S1 and S2) and two types of sludge (A and W) were tested. It was observed that βopt can be determined when the initial water content of the soil used in the mixture is lower than the optimum water content determined from the Proctor curve of the soil alone (10 wt% and 6 wt% for soils S1 and S2, respectively) and that βopt does not change with increasing initial soil water content. Optimum wet sludge contents found were low (≈15 wt% and ≈7 wt% for mixtures containing soils S1 and S2, respectively) for the test conditions, indicting a limited quantity of reusable sludge in the mixtures. For all mixtures, the water content corresponding to βopt was close to the optimum water content of the soil alone. Results of soil water retention and saturated hydraulic conductivity (ksat) tests conducted on selected optimized mixtures indicated that the mixtures based on soils S1 and S2 have air entry values higher than 20 kPa and would be suitable for use in the moisture retention layer of covers with capillary barrier effects, while soil S2 and the derived mixtures exhibited ksat < 10−7 cm/s and would be potential materials for the low permeability layer in low saturated hydraulic conductivity covers. [ABSTRACT FROM AUTHOR]

Coal washing plants produce large amounts of waste, and tailings are generally dumped in piles and impoundments nearby the plants. Sulfide minerals, water infiltration, and oxygen diffusion can result in acid mine drainage (AMD). In this paper, monitoring the AMD generated by a coal washing plant in northeastern Iran was investigated by applying time-lapse 2D and 3D geoelectrical techniques. For this purpose, 2D and 3D geoelectrical surveys with the Dipole-Dipole array were conducted in the area surrounded by an abandoned pile and nearby two impoundments. The surveys were repeated six months after the first measurements to characterize the temporal changes in the medium. 2D geoelectrical time-lapse suggests that the AMD is being generated at the shallower level of the pile. Moreover, the 3D time-lapse and hydrogeochemical analysis indicate that the likely plume is conveyed to the groundwater downstream of the pile. Besides, the results of time-lapse 3D geoelectrical models illustrate that seasonal changes, mainly precipitation, could affect the likely plume and transport it to subsurface layers. [ABSTRACT FROM AUTHOR]

This paper presents an easy-to-understand and easy-to-use methodology for monitoring the neutralization potential of residues derived from coal preparation. The methodology was developed based on the chemical composition of the waste and the relationship between calcium and sulfur. The effectiveness of this, in the control of residues, is demonstrated through in situ testing in a coal preparation plant in San Juan de Sabinas, Coahuila. The tests were carried out by collecting samples in three waste streams for five days at the plant. The methodology presents a strong linear correlation between the neutralization potential and the Ca/S ratio of 0.91. The estimation of neutralization potential through the Ca/S ratio represents a practical, easy-to-apply methodology that saves time and favors the decision-making required by waste management plans, to avoid the generation of acid drainage in coal waste. [ABSTRACT FROM AUTHOR]

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Containment and remediation of copper mine contamination with high concentration of heavy metals (Cu, Pb, Zn) and low pH (2–5) demand barriers with low hydraulic conductivity (k) and good chemical compatibility. To prepare modified barriers containing copper erosion by replacing Wyoming bentonite with local bentonite and screen out economic dosage, the k of 12 polymer-modified bentonites with sodium polyacrylate (PAA) or sodium-carboxymethyl cellulose (CMC) at dosages from 2 to 10%, was measured by modified fluid loss (MFL) test. The k of unmodified bentonites at 690 kPa top pressure ranged from 1.8 × 10−11 m/s to 1.9 × 10−11 m/s, which were reduced down to 4.6 × 10−12 m/s by 5% PAA or to 5.5×10−12 m/s by 5% CMC. The SEM & EDX-substantiated pore-filling effect of PAA, exfoliation of bentonite plates by PAA and CMC, and the XRD & FTIR-substantiated intercalation of CMC contributed to the decrement of available flow space and the increment of tortuosity of flow channel, and eventually k reduction. Excessive polymer (> 5%) might prop open interaggregate voids, increase pore connectivity and cause slight k increment up to 9.8 × 10−12 m/s and 6.5 × 10−12 m/s for 10% PAA- and 10% CMC-modified bentonites, respectively. Acidic condition (pH = 3) slightly increased the k of unmodified, 5% PAA- and 5% CMC-modified bentonite by less than 42%. At Cu2+ concentrations ([Cu2+]) of 0.38−10 mM (26 times the field concentration, 3.6 times the maximum concentration in the investigation), the k of 5% CMC-modified bentonite remained at 10−12 m/s, demonstrating good chemical compatibility. This was attributed to the intercalated CMC chains, which increased interlayer repulsion, enhanced osmotic swelling of bentonite plates, and reduced cation exchange reaction with Cu2+ at bentonite plate surfaces. When [Cu2+] reached 15 mM, k of 5% CMC-modified bentonite further increased to 6.0×10−11 m/s. This paper filled the gap of creating low permeable polymer-modified bentonite for permeants with acidic and high heavy metal content condition, which is typical near copper mines. The outcome of this research results in practically usable barrier materials, as used in a geosynthetic clay liner (GCL) or similar applications without the need of importing high-purity bentonite (e.g., Wyoming bentonite). [ABSTRACT FROM AUTHOR]

Combining environmental isotope analysis with principal component analysis can be an effective method to discriminate the inflows and sources of contamination in mining-affected watersheds. This paper presents a field-scale study conducted at an acid mine drainage (AMD)-contaminated site adjacent to a pyrite mine in South China. Samples of surface water and groundwater were collected to investigate transport in the vadose zone using stable isotopes of oxygen (δ18O) and hydrogen (δD) as environmental tracers. Principal component analysis of hydrogeochemical data was used to identify the probable sources of heavy metals in the AMD. The heavy metal pollution index (HPI) was applied to evaluate the pollution status of heavy metals in the groundwater. The groundwater associated with the Datai reservoir was recharged by atmospheric precipitation and surface water. On the side near the AMD pond, the groundwater was significantly affected by the soluble metals produced by pyrite oxidation. The concentrations of some metals (Al, Mn, and Pb) in all of the samples exceed the desirable limits prescribed by the World Health Organization (Guidelines for drinking-water quality, 4th edn. World Health Organization, Geneva, 2011). Among them, the concentration of Al is more than 30,000 times higher than the desirable limits prescribed by the World Health Organization (2011), and the concentration of Mn is more than 3000 times higher. The HPI values based on these heavy metal concentrations were found to be 10–1000 times higher than the critical pollution index value of 100. These findings provide a reference and guidance for research on the migration and evolution of heavy metals in vadose zone water in AMD-contaminated areas. [ABSTRACT FROM AUTHOR]

Abandoned sterile dumps can be a significant source of environmental pollution, therefore the distribution of trace elements throughout mining is vital. Monitoring environmental factors in closed mining perimeters aims to track the quality of discharged waters in the emissary and assess acid mine drainage, the quality of the soil and vegetation, stability, and the condition of the land surfaces within the perimeter of the sterile deposits. One of the primary sources of land, water and air pollution is sterile mining dumps. Knowing the source of pollution is the first step in adequately managing the affected areas. This paper investigates the physical–chemical properties and the concentrations of heavy metals in sterile dumps resulting from mining. We studied one sterile dump that was the result of ore processing and whose surface was covered with abandoned mixed ore concentrate (Pb, Zn), located in the Băiuț mining area (Romania), and a second sterile mining dump that was the result of exploration and exploitation work in the Ilba mining area (Romania). In order to determine the physicochemical characteristics of the studied sterile dumps and to determine the concentration of heavy metals, 27 sterile samples and one soil sample were taken from the Băiuț dump. Additionally, 10 sterile samples and one soil sample were collected from the Ilba dump. Aqua regia extractable concentrations of heavy metals were determined by inductively coupled plasma optical emission spectrometry. At the same time, using a portable XRF, we analyzed selected samples from each site for total metal concentrations. Furthermore, from each site, one sample was analyzed by FT–IR spectrometry. The pH values in both sterile dumps were highly acidic (≤3.5) and the content of heavy metals was generally increased. [ABSTRACT FROM AUTHOR]

Mercury (Hg) is a highly toxic and persistent heavy metal pollutant. The acid mine drainage (AMD) environment in sulfide-mining areas is a typical Hg pollution source. In this paper, the transformation of Hg2+ during anaerobic S0 reduction by an AMD environmental enrichment culture was studied by multiple spectroscopic and microscopic techniques. The experimental results showed that the microbial S0 reduction of the AMD enrichment culture was significantly inhibited in the presence of Hg2+. The results of cell surface morphology and composition analysis showed that there was obvious aggregation of flocculent particles on the cell surface in the presence of Hg2+, and the components of extracellular polymeric substances on the cell surface changed significantly. The results of surface morphology and C/S/Hg speciation transformation analyses of the solid particulate showed that Hg2+ gradually transformed to mercuric sulfide and Hg0 under anaerobic S0 reduction by the AMD enrichment culture. The microbial community structure results showed that Hg2+ significantly changed the enrichment community structure by decreasing their evenness. The dominant microorganisms with S0 reduction functions are closely related to mercury transformation and are the key driving force for the transformation of substrate solid particulate and cellular substances, as well as the fixation of Hg2+. [ABSTRACT FROM AUTHOR]

As naval forces continue to be increasingly present in today's operational environment, European maritime forces are poised to successfully exploit autonomous mine countermeasures (MCM) technology, not only to save manpower but also to increase operational efficiency. Successfully detecting and removing mines from the maritime environment (especially drifting mines, which have re-emerged in the spotlight following the outbreak of war in Ukraine in February 2022) remains a key requirement for maritime forces trying to maintain the security of waterways and oceans around the world. The overall objective of the project, which is the subject of this paper, is to develop and integrate autonomous means (UAVs and USVs) into the concept of action of specialized forces for the search and identification of sea mines. As a starting point in the definition of the overall objective, it has been taken into account that the intervention of specialized forces to neutralize explosive devices involves a series of complex actions, including search, detection, identification, location-based assessment, safe destruction/neutralization, recovery, and destruction of improvised explosive devices or munitions. [ABSTRACT FROM AUTHOR]

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Sulfate-laden wastewater generated from various natural and industrial activities, including mining, metallurgy, electroplating, and battery manufacturing and recycling, has the potential to contaminate both ground and surface water bodies. It is harmful to all forms of life and the environment. Thus, developing an efficient treatment system to address sulfate pollution is necessary. Biological sulfate reduction (BSR) involving sulfate-reducing bacteria offers a better removal of sulfate than conventional physicochemical methods. BSR offers various advantageous such as lower sludge production, removal and recovery of metals, and production of elemental sulfur. However, the performance of bioreactors depends on wastewater sources, microbes involved, and operating conditions. Currently, limited studies are available encapsulating the current state of the art of biological sulfate remediation aimed at optimization of bioreactor design and operation. Therefore, this paper attempts to provide a comprehensive review of the sources of sulfate, its health and ecological effects, microbes involved in sulfate reduction, and its removal pathways that would be beneficial for future bioreactor design. In addition, theoretical and practical aspects of influencing factors the process parameters have been discussed. Considering the results of the reviewed articles, operating, and set-up conditions are recommended to obtain the higher sulfate removal. It includes dissimilatory sulfate reduction by mixed bacterial culture using sodium lactate as an electron donor with pH near about neutral, mesophilic conditions, COD SO4 2-/ratio of 0.67-1.7, ORP less than -100 mV, and lesser sulfide concentration. This overview helps to develop an effective strategy for bioremediation of sulfate and decreasing the sulfate-rich industrial effluent footprint. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Water Treatment is the property of CNOOC Tianjin Chemical Research & Design Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Mine Water & the Environment is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The treatment of acid mine drainage is critical to environmental sustainability. At present, the use of sulfate-reducing bacteria to remediate acid mine drainage has attracted the attention of domestic and foreign researchers due to its advantages of high efficiency, environmental friendliness, and safe and pollution- free. Therefore, this paper reviewed the literature on the treatment of add mine drainage by sulfate-reducing bacteria, reviewed the sources and hazards of acid nine drainage, and summarized the mechanism of sulfate-reducing bacteria to remove high sulfate and metals in add mine drainage. And in this paper, the main factors affecting the treatment of acid mine drainage by sulfate reducing bacteria are introduced in detail and the bioreactor system based on sulfate reduction is described. Finally, the prospect of research on the treatment of add mine drainage by sulfate- reducing bacteria has prospected and some suggestions are put forward. [ABSTRACT FROM AUTHOR]

It is a major problem to remediate the uranium contaminated groundwater at an acid in-situ leaching uranium mine. In this paper, phytic acid was hydrolyzed by the hydrothermal reaction to obtain phytic acid hydrolyzate, and the simulated uranium contaminated groundwater was prepared according to the physicochemical characteristics of uranium-contaminated groundwater at an acid in-situ leaching uranium mine. The effect of the amount of added phytic acid hydrolyzate and its pH value on the removal performance of U( VI) from the uranium contaminated groundwater was explored, and the concentrations of phosphate anion, calcium ion, total iron ion, manganese ion, zinc ion, and magnesium ion were monitored, and the mechanism for the remediation of uranium contaminated groundwater was analyzed by SEM, TEM, XPS and XRD. The results show that when the amount of the addied phytic acid hydrolyzate was 2 mL, the concentration of phosphate was 24.562 g/L, the initial pH value was 6, the amount of simulated uranium contaminated groundwater was 100 mL, its initial pH value was 3, its uranium concentration was 5 mg/L, and the reaction time was 12 h, the removal rate of uranium reached more than 99%, and the pH value was raised to 5.9. The current research verified that it is feasible to use phytic acid hydrolyzate to remediate the uranium contaminated groundwater at add in-situ leading uranium mine. Since phytic add is cheap and easy to obtain, it can be used as an economical phosphorus source to replace expensive phosphate compounds for the remediation of uranium-contaminated groundwater at the mine. [ABSTRACT FROM AUTHOR]

The spontaneous combustion of coal storage piles and gangue piles in coal mines has been resulting in significant resource waste and serious environmental pollution. To solve spontaneous combustion problems, the use of gravity heat pipes to extract internal heat from piles of coal has been proposed. In this paper, a method for selecting the optimum working medium for a heat pipe is presented. In addition, an experimental system was set up to study a gravity heat pipe's heat extraction rate, and a gravity heat pipe heat dissipation experiment was conducted. The experimental results showed that compared with using ethanol or hexane as the working medium, a methanol gravity heat pipe had the highest efficiency and provided the fastest cooling rate. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) is a leachate that may occur naturally or be produced at mining sites and tailings deposits. Characteristically, AMD consists of effluents with extremely low pH (4.0) and a high concentration of heavy metals; therefore, it is highly toxic. Due to the impact that these effluents have on the environment, effective and low-cost methods for AMD treatment have been developed. As an important strategy for pH increase and metal-ion precipitation, there are biological treatment methods, in which bioreactors containing biocatalysts, such as sulfate-reducing bacteria, are applied. Regarding the applicability of microbial fuel cells (MFCs) for the treatment of effluents, this technology can be an innovative and promising alternative for AMD treatment. This paper aims to review the biological treatments already employed for the treatment of effluents containing sulfates and/or metals and to evaluate the adaptability of such methodologies for AMD treatment, using MFCs. Studies indicate that the MFC technology has a very promising application in the treatment of water with high concentrations of sulfate and heavy metals. It shows great advantage over other strategies, since it does not require the addition of chemical compounds, besides generating energy, thus being self-sustainable. [ABSTRACT FROM AUTHOR]

This paper describes a system for the automatic determination of rock-breaking target poses for impact hammers used in underground mines. The rock-breaking target pose is defined as the position and angle at which the impact hammer must strike a rock in order to break it. The automatic determination of this pose is essential for the autonomous operation of an impact hammer. The proposed system takes as input sensor data composed of point clouds and images, and automatically determines a rock-breaking target pose. The system consists of a rock segmentation subsystem that receives the sensor data and identifies and individualizes the rocks/boulders present above the grizzly, and a rock-breaking target pose generation and evaluation subsystem that receives the rock information produced by the rock segmentation subsystem, and generates a list of rock-breaking target pose candidates, it evaluates them, and it selects the best candidate as the rock-breaking target pose. The system is evaluated using real data. The reported experiments show the system's capability to generate appropriate target poses. [ABSTRACT FROM AUTHOR]