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• OS-P formed more amorphous charcoal-like graphite microcrystalline structure at 600℃. • The pyrolysis treatment could make the speciation of heavy metals more stabilized. • The environmental risks and ecological safety of OS-P are controllable. • OS-P can be considered as agricultural sludge. Solid-phase residues from pyrolysis of oily wastes (OS) are widely used due to their rich pore structure and strong adsorption capacity. In this study, pyrolysis residues (OS-P) were obtained from the pyrolysis treatment of four typical OS in Karamay, Xinjiang. The results indicate that the crystalline substances in OS-P mainly were SiO 2 , BaSO 4 , and graphite. The heavy metals of OS-P were higher than that of OS in the following order: Zn > Cu > Ni > Cr > Pb > Cd. The results of the improvement of Community Bureau of Reference (BCR) sequential extraction showed that the proportion of Cu, Ni and Cr in OS1-P in the residual fraction was higher than that of the other three OS. The residual fraction of Cu, Ni, and Cr in OS1-P increased from 16.0 %, 30.0 %, and 11.0 % to 66.1 %, 81.9 %, and 89.2 %, respectively. After pyrolysis treatment, the leaching concentration of heavy metals in the residue was reduced. Referring to the requirements for heavy metal control limits (GB 4284–2018), all heavy metals in OS-P showed low risk. Their potential ecological risk indices were 4.11, 3.13, 4.87 and 5.35, respectively, indicating that the potential ecological hazards of heavy metals from OS-P were slight. There was no significant effect on the histopathological changes of kidney, lung, liver, ovary and testis of mice, showing that the rational use of OS-P in production will not produce toxic effects on target animals. Based on risk assessment and safety evaluation, the application of OS-P is controllable, safe and reliable for resource utilization. [ABSTRACT FROM AUTHOR]

[Display omitted] • Heavy metals in MSWI fly ash were reduced into alloy by SAD. • Reduction rates of iron and zinc were 67 and 100% • Transparent glass for building was made from MSWI fly ash. • 115 ∼ 213 dollars were earned after disposing of 500 kg of MSWI fly ash. Municipal solid waste incineration (MSWI) fly ash is a hazardous waste containing heavy metals. Secondary aluminum dross (SAD) is a hazardous waste discharged from aluminum smelting, containing active aluminum nitride (AlN). In this work, heavy metals from MSWI fly ash were reduced into alloy by AlN from SAD, and the slag was manufactured into transparent glass for building. Reduction of iron and zinc was 67 and 100 %, respectively. Reduction mechanism was explored after applying XRD, XRF and thermodynamics analysis. It was found that the reduction reaction was an ion reaction. The AlN and heavy metal oxide transformed into anionic group containing nitrogen and heavy metal cation, after entering slag. The heavy metals were reduced into alloy after electron was transferred from anionic group to cation. In addition, the reduced iron and zinc could merge into alloy, which inhibited evaporation of zinc. Yellow transparent glass was obtained after the reduction process. Yellow was come from titanium oxide, which could not be reduced by AlN. Microhardness, density and water absorption of the transparent glass were 741 HV, 2.86 g·cm−3 and 0.04 %, respectively. Leaching content of Ni, Cu, Zn and Pb of the glass were 0.1, <0.1, 0.6 and < 0.1 mg/L, respectively, all below the TCLP limit. About 115 ∼ 213 dollars were earned after manufacturing 500 kg of MSWI fly ash into transparent glass. This work provided a novel idea of recycling solid waste into alloy and transparent glass for building. [ABSTRACT FROM AUTHOR]

[Display omitted] • More than 99.7 % of vancomycin was removed from vancomycin fermentation residue. • The residual antibiotic resistance genes were completely degraded. • Hydrothermal treatment and pyrolysis promoted immobilization of heavy metals. • Environmental risks of heavy metals were significantly reduced after treatments. • Toxicity tests demonstrated the detoxification effect of the treatment methods. Vancomycin fermentation residue (VFR) is a by-product of the pharmaceutical industry with high ecotoxicity caused by the residual antibiotics, antibiotic resistance genes (ARGs), and heavy metals (HMs). In this study, the detoxification effect of hydrothermal treatment (HT) and pyrolysis for VFR was assessed using chemical analysis and toxicity tests. When VFR was subjected to HT and pyrolysis at ≥400 °C, more than 99.70 % of the residual vancomycin and all ARGs were removed. The HMs contents in VFR followed the order of manganese (676.2 mg/kg) > zinc (148.6 mg/kg) > chromium (25.40 mg/kg) > copper (17.20 mg/kg), and they were highly bioavailable and easily leached. However, HT and pyrolysis (≥400 °C) substantially reduced the bioavailable fractions and leaching properties of the HMs. After HT and pyrolysis at ≥ 400 °C, the potential ecological risk of HMs in VFR was reduced from considerable to moderate/low levels. The elutriate acute toxicity test suggested that HT and pyrolysis at ≥ 400 °C effectively reduced the toxicity of VFR to an acceptable level (p < 0.05). This study demonstrates that HT and pyrolysis (≥400 °C) are promising methods for treating VFR and detoxifying it, and the treated products are safe for further reutilization. [ABSTRACT FROM AUTHOR]

In recent years, researchers have prepared glass-ceramics using a mixture of multiple solid waste materials, which is an effective and resourceful way to use and store solid waste. However, solid waste usually contains multiple heavy metals, which presents challenges during the mixing and co-solidification processes. In this study, high-performance glass-ceramics with low leaching were prepared from blast furnace slag (BFS). The synergistic curing mechanism of BFS glass-ceramics for heavy metals Cr, Mn, Cu, Zn, Ni, and Co was investigated in detail, as well as the migration pattern and storage state of heavy metals under different heat treatment stages and different Cr contents. The results show that the increases in temperature and Cr 2 O 3 content contribute to the incorporation of heavy metals into the crystal lattice and promote crystal growth. Excessive crystallization of spinel causes aggregation, which further curtails the leaching of heavy metals. The leaching concentration of heavy metals mainly depends on the heavy metal content in the glass network and the degree of network polymerization. Thus, spinel acts as a crystal core for the solidification of heavy metals, while augite and glass phases act as a double barrier to physically encapsulate them, which is effective for the storage of a wide range of heavy metals. Furthermore, the physical and chemical properties of BFS glass-ceramics are consistent with the Chinese industry standard "Glass-ceramics plate for industrial application" (JC/T 2097-2011). This study provides important theoretical support for the synergistic solidification of multiple heavy metals in glass-ceramics, as well as insights into the preparation of glass-ceramics by mixing BFS with other solid wastes. [Display omitted] [ABSTRACT FROM AUTHOR]

• Sulphate decomposition by galvanic sludge calcination forms a spinel solution. • The amount of kaolin and red clay influences the formation of a spinel solid solution. • Reuse of 300 tons/year of galvanic sludge helps Amazonian rainforest preservation. • Amazonian clays guarantee the sustainability of a highly toxic environment. This study presented the influence of two types of clay: kaolin (Kao) and red clay (RC) on the chemical and physical properties of ceramic specimens when galvanic sludge (GS) is incorporated to encapsulate heavy metals. Samples were obtained of GS from the industrial district of Manaus – Amazonas State, Brazil, and kaolin (Kao), and red clay (RC) from the Central Amazon. A fourth sample was prepared by mixing GS, Kao, and RC in the ratio 1:1:8 (GS + Kao + RC). This mixture was ground, and ceramic specimens were prepared, and heat treated at 950 °C and 1200 °C for three hours for phase detection, compressive strength, leaching of Fe, Ni and Cr metals and life cycle assessment. Galvanic sludge, Kao, and RC were also, and heat treated to at 950 °C and 1200 °C for three hours, obtaining GS950, GS1200, Kao950, Kao1200, RC950, and RC1200. The samples were submitted to XRF, XRD, Rietveld refinement, Mössbauer spectroscopy, TG/DTG/DSC, and SEM. The results show that the formation of nickel oxide and a spinel solid solution of the type F e 3 + { F e 1 - y 3 + , F e 1 - x 2 + , N i x 2 + , C r y 3 + } O 4 (in which [] = tetrahedral site, {} octahedral site) occurs in GS1200, which is caused by sulfate decomposition to SO 2. At 1200 °C, heavy metals are encapsulated, forming other phases such as nickel silicate and hematite. Life cycle assessment was used to verify the sustainability and value of GS in clay for making bricks, and it indicated that the production of ceramics is feasible, reduces the use of clays, and is sustainable. [ABSTRACT FROM AUTHOR]

• Oxygen carrier (OC) promotes the contact between fuel and oxygen in rotary kiln. • OC has capacity for K adsorption during solid waste incineration. • OC enhances hazardous heavy metals retention in the fuel bottom ash. • The leaching toxicity of heavy metals from OCs fully respects Chinese standard limits. Rotary kiln (RK) incineration technology gains prominence in waste management, aiming to reduce pollution, recover energy, and minimize waste. Oxygen-carrier (OC)-aided incineration of waste in the RK demonstrates notable benefits by enhancing oxygen distribution uniformity and facilitating fuel conversion. However, the effects of OC on ash-related alkali and heavy metals during waste incineration in the RK remain unknown. In this study, manganese ore and ilmenite as OCs are introduced into RK during waste combustion, focusing on their effects on the bottom ashes and the behavior of alkali and heavy metals. Results show that manganese ore exhibits a decreasing reactivity due to oxygen depletion during the conversion from Mn 2 O 3 to Mn 3 O 4 , while ilmenite maintains good reactivity due to sustained enrichment of Fe 2 O 3 on the particles even after multiple cycles in RK. The porous structure on the surface of OCs particles verifies the cyclic reaction involving oxidation by air and reduction by fuel as OCs move between the active and passive layers of the bed. The porous OCs particles offer abundant adsorption sites for K from the gaseous phase, with surface-deposited K migrating into the particles and enhancing the OCs' capacity for K adsorption. Adding OCs promotes the formation of stable, less volatile compounds of heavy metals (As, Cr, Pb, and Zn) and enhances their retention in bottom ash while ensuring the leaching toxicity remains below Chinese national standard limits. This study enhances the understanding of OCs in incineration, guiding vital references for waste management practices and environmental sustainability. [ABSTRACT FROM AUTHOR]

[Display omitted] • The release of Zn and Pb were mitigated by the synergistic effect. • Bioavailable fractions of HMs were reduced by SiO 2 and Al 2 O 3 from the sludge. • Bioavailable phosphorus was increased from 18.79 to 49.69 mg/g by co-pyrolysis. Phosphate tailings (PT) was used to reduce the release of heavy metals (HMs) during pyrolysis and the leachable rate of residual HMs, and simultaneously improve the bioavailability of phosphorus in the sludge-based biochar. The concentration of heavy metals and the fractions determined by BCR method was used to investigate the release and the transformation of Zn, Pb, Mn, Ni and Cu during pyrolysis involved with the effects of temperature and the addition of PT. The respective pyrolysis experiments shows that the release of Zn and Pb increases with temperature for both sewage sludge (SS) and PT, and the bioavailable fractions (F1 + F2) of Mn, Ni, and Cu increases with temperature for PT. During co-pyrolysis, blended samples released lower quantities of Zn and Pb and presented lower bioavailability of HMs than the individual SS or PT. A synergistic effect of co-pyrolysis was evident for volatile Zn and Pb. The decomposition of CaMg (CO 3) 2 from PT produced CaO, by which the volatile ZnCl 2 and PbCl 2 were transformed into ZnO and PbO with less volatility and higher reactivity with SiO 2 and Al 2 O 3 than the chlorides. Then SiO 2 and Al 2 O 3 from SS acted as the final stabilizer to immobilize the oxides. The final product combined with SiO 2 and Al 2 O 3 , such as ZnSiO 4 and ZnAl 2 O 4 , were detected. The addition of PT also introduced more Ca and P into sludge to produce biochar with higher concentration of apatite phosphorus with higher bioavailability. [ABSTRACT FROM AUTHOR]

• This paper addresses the pressing issue of heavy metal pollution's impact on crop plants. • It delves into plant stress tolerance mechanisms, including reduced metal uptake, phytochelatin binding, and robust antioxidant systems. • The study employs advanced omics technologies such as genomics, transcriptomics, miRNAomics, metallomics, and metabolomics to decode these processes. • These insights offer practical methods for enhancing crop stress tolerance and developing resilient genotypes. In the wake of rapid industrialization and human-induced environmental changes, toxic heavy metal pollution has become a widespread concern, posing a significant threat to crop plants. This paper explores the mechanisms of plant stress tolerance in the face of heavy metal toxicity. Plants have evolved defense strategies, including reduced metal uptake, phytochelatin binding, and robust antioxidant systems, to counter these challenges. Our study focuses on deciphering these mechanisms through advanced omics technologies like genomics, transcriptomics, miRNAomics, metallomics, and metabolomics. These insights offer practical methods to enhance stress tolerance in crops and develop resilient genotypes. Key enzymes such as peroxidase, superoxide dismutase, and catalase, along with non-enzymatic antioxidants like ascorbic acid, play pivotal roles in plant defense against heavy metal stress. Both essential and non-essential metals induce adverse effects in plants, from inhibited growth to impaired photosynthesis, ultimately impacting plant survival. Effective defense tactics involve not only enzymatic and non-enzymatic antioxidants but also root exudates and cell wall reinforcement. This review provides a concise exploration of the complex mechanisms underlying plant stress tolerance, covering metal uptake, transport, damage, and chelation within cellular components. It sheds light on how plants adapt to thrive amidst these challenging stress factors. [ABSTRACT FROM AUTHOR]

• High specific surface area reusable UiO66 composites were synthesized. • UiO66 composites maintains high adsorption capacity for Metal-EDTA complexes in soil. • UiO66 composites application improved the efficiency of EDTA-assisted washing. • Magnetic fields achieved harmful heavy metal recovery from the soil. • UiO66 composites reduced residual heavy metals mobility of soil. The coupling of washing with adsorption process can be adopted for the treatment of soils contaminated with heavy metals pollution. However, the complex environment of soil and the competitive behavior of leaching chemicals considerably restrain adsorption capacity of adsorbent material during washing process, which demands a higher resistance of the adsorbents to interference. In this study, we synthesized strongly magnetic, high specific surface area (573.49 m2/g) UiO66 composites (i.e., UiO66-Fe 3 O 4) using hydrothermal process. The UiO66-Fe 3 O 4 was applied as an adsorbent during the ethylene diamine tetraacetic acid (EDTA)-assisted washing process of contaminated soil. The incorporation of UiO66-Fe 3 O 4 results in rapid heavy metal removal and recovery from the soil under low concentrations of washing agent (0.001 mol/L) with reduced residual heavy metal mobility of soil after remediation. Furthermore, UiO66-Fe 3 O 4 can quickly recollect by an external magnet, which offers a simple and inexpensive recovery method for heavy metals from contaminated soil. Overall, UiO66-Fe 3 O 4 configuration with EDTA-assisted washing process showed opportunities for heavy metals contaminated sites. [Display omitted] [ABSTRACT FROM AUTHOR]

• The transformation of birnessite and its environmental implications were reviewed. • The relationship between transformation pathways and mechanisms of birnessite and environmental conditions was proposed. • The stabilization mechanisms of heavy metals in the transformation process were summarized. Birnessite is ubiquitous in the natural environment where heavy metals are retained and easily transformed. The surface properties and structure of birnessite change with the changes in external environmental conditions, which also affects the fate of heavy metals. Clarifying the effect and mechanism of the birnessite phase transition process on heavy metals is the key to taking effective measures to prevent and control heavy metal pollution. Therefore, the four transformation pathways of birnessite are summarized first in this review. Second, the relationship between transformation pathways and environmental conditions is proposed. These relevant environmental conditions include abiotic (e.g., co-existing ions, pH, oxygen pressure, temperature, electric field, light, aging, pressure) and biotic factors (e.g., microorganisms, biomolecules). The phase transformation is achieved by the key intermediate of Mn(III) through interlayer-condensation, folding, neutralization-disproportionation, and dissolution-recrystallization mechanisms. The AOS (average oxidation state) of Mn and interlayer spacing are closely correlated with the phase transformation of birnessite. Last but not least, the mechanisms of heavy metals immobilization in the transformation process of birnessite are summed up. They involve isomorphous substitution, redox, complexation, hydration/dehydration, etc. The transformation of birnessite and its implication on heavy metals will be helpful for understanding and predicting the behavior of heavy metals and the crucial phase of manganese oxides/hydroxides in natural and engineered environments. [Display omitted] [ABSTRACT FROM AUTHOR]

• Fe oxyhydroxides are the common dominant phase for As, Cd, Pb and Zn. • Paulmooreite is an important mineral host for Pb and As. • The leaching of Pb, Zn, Cd and As exhibit a strong dependence on pH. • Fe oxyhydroxides and secondary insoluble minerals are the solubility-controlling phases. The lack of understanding of heavy metal speciation and solubility control mechanisms in smelting soils limits the effective pollution control. In this study smelting soils were investigated by an advanced mineralogical analysis (AMICS), leaching tests and thermodynamic modelling. The aims were to identify the partitioning and release behaviour of Pb, Zn, Cd and As. The integration of multiple techniques was necessary and displayed coherent results. In addition to the residual fraction, Pb and Zn were predominantly associated with reducible fractions, and As primarily existed as the crystalline iron oxide-bound fractions. AMICS quantitative analysis further confirmed that Fe oxyhydroxides were the common dominant phase for As, Cd, Pb and Zn. In addition, a metal arsenate (paulmooreite) was an important mineral host for Pb and As. The pH-stat leaching indicted that the release of Pb, Zn and Cd increased towards low pH values while release of As increased towards high pH values. The separate leaching schemes were associated with the geochemical behaviour under the control of minerals and were confirmed by thermodynamic modelling. PHREEQC calculations suggested that the formation of arsenate minerals (schultenite, mimetite and koritnigite) and the binding to Fe oxyhydroxides synchronously controlled the release of Pb, Zn, Cd and As. Our results emphasized the governing role of Fe oxyhydroxides and secondary insoluble minerals in natural attenuation of heavy metals, which provides a novelty strategy for the stabilization of multi-metals in smelting sites. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Commercially treated incineration bottom ashes show distinctive characteristics. • Seawater promotes leaching of elements and needs attention in coastal regions. • Elements are categorized with different mobilities and controlled mechanisms. • Element leaching behaviors are categorized to improve long-term assessment. Leaching of potentially hazardous substances, especially the heavy metals from Incineration Bottom Ash (IBA) is a major problem in its recyclable usage. To address this concern, treatment of IBA is indispensable before it can be reused. IBA subjected to laboratory-scale treatment typically yields clearer conclusions in terms of leaching behaviors, benefiting from the controlled laboratory environment. However, the leaching behaviors of commercially treated IBA appear to be more ambiguous due to the complex and comprehensive nature of industrial-scale treatments, where multiple treatment techniques are involved concurrently. Furthermore, treatment efficiencies vary among different plants. In this study, three types of commercially treated IBA were sampled from leading waste treatment companies in Singapore. Characterization and leaching tests were performed on the treated IBAs in both standardized and modified manners to simulate various scenarios. Besides deionized water, artificial seawater was used as a leachant in leaching tests for simulating seawater intrusion. The results reveal the promoting effect of seawater on the leaching levels of several elements from three types of treated IBA, which may require special attention for IBA application and landfill near the coast. Furthermore, the elements examined in these three types of commercially treated IBA generally comply with the non-hazardous waste acceptance criteria outlined in Council Decision, 2003 /33/EC (2003), except Sb. By combining two leaching tests, the elements were categorized into different types of leaching behavior, making it possible to prepare and respond to the concerning leaching scenarios in future engineering applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Municipal solid waste incineration fly ash (MSWIFA) and phosphorous slag (PS) were investigated for solidified body. • The MSWIFA/PS solidified body is an environmentally friendly and efficient binder. • The MSWIFA/PS immobilized Zn 99.9 %, Pb 99.4 % and Cd 99.8 % in 60 day leaching tests. • Immobilization mechanism of the MSWIFA/PS was analyzed with XRD, TG-DTG and SEM-EDS. Municipal solid waste incineration fly ash (MSWIFA) contains potential contaminants and needs to be efficiently solidified/stablized and so should be managed properly. To achieve this goal, alkali-activated MSWIFA and phosphorus slag (PS) based geopolymer solidified bodies were investigated. Therefore, the mechanical properties of the solidified body, heavy metal leaching characteristics, heavy metal chemical forms, and heavy metal solidification/stabilization mechanisms were also analyzed. The results show that: The addition of an appropriate amount of PS can promote the strength development of a solidified body. When the mass ratio of MSWIFA to PS is 7:3, the strength of the solidified body reaches 22.8 MPa at 90d curing age, which is 5.3 times higher than that of the unmodified material. The MSWIFA/PS immobilized Zn 99.9 %, Pb 99.4 % and Cd 99.8 % in 60 day leaching tests. Meanwhile, PS can significantly increase the proportion of chemically stabilized forms of heavy metals in the solidified body. PS affects on the hydration process of the solidified body. When the mass fraction of PS doping was 30 %, the main hydration products of the solidified body were calcium silicate hydrate (C-S-H) and calcium alumina (AFt). When the mass fraction of PS is 50 %, the main hydration products are calcium aluminosilicate hydrate (C-A-S-H), sodium aluminosilicate hydrate (N-A-S-H), and AFt. These hydration products have good solidification effects on heavy metals. Therefore, it can be concluded that the MSWIFA/PS solidified body is an environmentally friendly and efficient binder. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biochar amendment to the digestate-based bioponics improved plant yield. • Biochar adsorbed heavy metals and decreased their bioaccumulation in plants. • Noncancer and cancer risks were found from ingestion of the plants. • Biochar enhanced microbial communities, aiding metal stabilization in bioponics. • Biochar promoted genera in sludge and plant roots for efficient P and N recovery. Bioponics is a nutrient-recovery technology that transforms nutrient-rich organic waste into plant biomass/bioproducts. Integrating biochar with digestate from anaerobic wastewater treatment process can improve resource recovery while mitigating heavy metal contamination. The overarching goal of this study was to investigate the application of biochar in digestate-based bioponics, focusing on its efficacy in nutrient recovery and heavy metal removal, while also exploring the microbial community dynamics. In this study, biochar was applied at 50 % w/w with 500 g dry weight of digestate during two 28-day crop cycles (uncontrolled pH and pH 5.5) using white stem pak choi (Brassica rapa var. chinensis) as a model crop. The results showed that the digestate provided sufficient phosphorus and nitrogen, supporting plant growth. Biochar amendment improved plant yield and phosphate solubilization and reduced nitrogen loss, especially at the pH 5.5. Furthermore, biochar reduced the heavy metal accumulation in plants, while concentrating these metals in the residual sludge. However, owing to potential non-carcinogenic and carcinogenic health risks, it is still not recommended to directly consume plants cultivated in digestate-based bioponic systems. Additionally, biochar amendment exhibited pronounced impact on the microbial community, promoting microbes responsible for nutrient solubilization and cycling (e.g., Tetrasphaera , Herpetosiphon , Hyphomicrobium , and Pseudorhodoplanes) and heavy metal stabilization (e.g., Leptolinea , Fonticella , Romboutsia , and Desulfurispora) in both the residual sludge and plants. Overall, the addition of biochar enhanced the microbial community and facilitated the metal stabilization and the cycling of nutrients within both residual sludge and root systems, thereby improving the overall efficiency of the bioponics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Heavy metals can controlled well in solid waste/sludge pyrolysis by vermiculite. • Interlayer spacing of vermiculite is positively correlated with heavy metal retention. • Heavy metals except Cd are at low potential ecological risk and 3IV reduces this risk. • Heavy metal oxides react more readily with vermiculite flakes than their chlorides. • The reactivity of Cr/Zn with vermiculite flakes is stronger than those of Cd/Pb/Cu. Pyrolysis is effective in reducing the volume of solid waste and sludge, and produces less pollutants than incineration and landfill, but the process still suffers from heavy metal pollution. Four types of intercalated-exfoliated modified vermiculite (UIV, DIV, TIV and 3IV) were prepared using urea, dimethylsulfoxide, tributyl phosphate and 3-aminopropyltriethoxysilane as intercalators for the control of Cd, Cr, Cu, Pb and Zn in municipal sewage sludge (MSL), paper mill sludge (PML), municipal domestic waste (MWA) and aged refuse (AFE). The larger the interlayer spacing of the vermiculite, the more favorable the retention of heavy metals. 3IV was the most effective additive, with an average retention of more than 75 % of all heavy metals at 450 ℃ for the four raw materials. Cr, Cu, Pb and Zn were all at low potential ecological risk (Pr), while Cd was moderate or considerable Pr, and the addition of 3IV reduced the Pr. Distribution of intercalators between vermiculite interlayers was haphazard, and interlayer spacing results were close to those of the experiment (except for tributyl phosphate). The reactive electrons mainly flowed from the Highest Occupied Molecular Orbital (HOMO) of vermiculite flakes to the Lower Unoccupied Molecular Orbital (LUMO) of heavy metal chlorides. In contrast, the reactive electrons mostly flowed from the HOMO of heavy metal oxides to the LUMO of vermiculite flakes. Heavy metal oxides were more readily adsorbed on vermiculite flakes than heavy metal chlorides, and the adsorption capacity of Cr and Zn was stronger than that of Cd, Pb and Cu. [ABSTRACT FROM AUTHOR]

• Silicon and nanosilicon mitigating the adverse effects of cadmium stress in fruit trees. • Silicon application enhancing the antioxidative capacity of fruit trees under cadmium stress. • Silicon supplementation increased fruit yield and reduced cadmium accumulation. • Silicon and nano silicon reduced oxidative damage in fruit crops under cadmium stress. For quality fruit production, balance fertilization and irrigation with good quality water had significant effects. The commercial production of fruits is badly affected due to heavy metals accumulation in soil. Among heavy metals, cadmium (Cd) is found in higher amount which greatly accumulate in fruits. Hence, consumption of such fruits causing different diseases in humans. Cd induced conditions decreased growth, yield and deteriorate fruit quality globally. Soil contaminated with Cd is mainly due to urbanization, industrialization and frequent application of chemicals. The absorption, uptake, translocation and accumulation of Cd is toxic for fruit crops. Cd stress resulted in oxidative stress and injury of cell wall due to toxic reactive oxygen species (ROS) production. Cell wall important functioning is protection from heavy metals entry into cytoplasm. Fruit tree produces antioxidant compounds which acts as scavengers of toxic ROS. Different management approaches i.e. molecular basis, mineral nutrients and proteomics can be adopted for mitigation of adverse of Cd on fruit crops. Among mineral nutrients, silicon (Si) and silicon nano-particles (Si-NPs) sprays are effective for mitigation of negative effects of Cd toxicity on fruit crops by improving antioxidant activities, osmolytes and photosynthetic pigments resulted in improved growth, yield, and quality. Current study encourages the application of Si and Si-NPs on fruit trees under Cd stress conditions. However, Si-NPs are more effective as compared to Si bulk form due to easier passage into cell wall. [ABSTRACT FROM AUTHOR]

• Continuous effluents and wastewater discharge contaminants the soil in the vicinity of Lyari River, Karachi. • Helianthus annuus, Zea mays and Brassica juncea plants successfully grown in the heavy metals contaminated soil. • Z. mays exhibited the higher tolerance against HMCS (based on growth attributes). • H. annuus was the best hyper accumulator plant related to other tested crops. • The physiological and biochemical attributes of plant are summarized and discussed. • Perspectives are presented for the potentials of pytoremediation in sustainable agriculture. Industrial and domestic effluents are often disposed of untreated or undertreated in developing countries resulting in the deposition of heavy metals in soil and water bodies. Karachi is the largest commercial hub of the country with many industries and the densely developed urban area. Lyari is one of the two major rivers of Karachi which has become a dumping site of the city's effluent. In the present study three crops- Helianthus annuus, Zea mays and Brassica juncea were grown in the heavy metals contaminated soil (HMCS) of Lyari River to explore their tolerance and phytoremediation potential. All the tested plants exhibited improved germination and growth in HMCS. The shoot length and plant biomass of all three cultivated species were high in HMCS. However, the tolerance against HMCS (based on growth attributes) of Z. mays was higher than other crops. The photochemistry and relative chlorophyll content of all plants were unaffected with HMCS. Although, H 2 O 2 content was high (around 25 %) but no change in antioxidant enzyme was found in H. annuus and B. juncea species under HMCS. In contrast, the enhanced activity of peroxidase and catalase enzymes in the shoot of Z. mays along with no increase in H 2 O 2 content is related with better plant growth in HMCS. H. annuus and B. juncea accumulated 40 % more Cu in shoots that are associated with high BAF and TF. High Zn accumulation in root (20 % more than shoot) of three cultivated species is related with <1 TF. Higher accumulation (40 % more than control) of Fe in H. annuus and Z. mays is linked with their BAF values. Among tested heavy metals, Mn accumulation was least (< 19 mg Kg−1) in all species. This study concluded that, Zea mays could be used as a best hyper-tolerant plant while H. annuus as the best hyper accumulator. [ABSTRACT FROM AUTHOR]

In this study, we investigated the impact of Pb/Co compositional ratios on the growth and phase transition of CsPbBr 3 within PbO-Bi 2 O 3 -B 2 O 3 glasses. We employed XRD Rietveld refinement and Raman spectra for a thorough analysis of structural modifications and crystal phases. To assess the morphology, size, and distribution of CsPbBr 3 crystals, as well as the homogeneity of embedded glasses, we utilized SEM and TEM, along with SAED patterns. The results confirmed a phase transition from cubic CsPbBr 3 to tetrahedral CsPb 2 Br 5 at Pb content exceeding 60%, leading, however, to severe crystallization and the transformation of glassy phases into ceramics. Expanding on the optimal 45% PbO content, we also explored the influence of CoBr 2. XRD refinement and Raman analysis revealed Co content-dependent growth and phase transition of CsPbBr 3 within the glasses. XPS studies demonstrated the coexistence of Co2+ and Co3+ ions, and their spin states and coordination were verified through XANES and EPR analysis. Notably, the presence of high-spin octahedral Co2+ replacing Pb in the B-site of perovskite resulted in observed ferromagnetism in the Co-doped glasses. Magnetization increased within the 1–3% Co content range. Simultaneously, a high-value Verdet constant of 108 rad/T·m at 633 nm was obtained, presenting an attractive feature for diamagnetic glasses. [ABSTRACT FROM AUTHOR]

• MKPC with low M/P ratios between 2 and 3 are more suitable for compressive strength development and heavy metal solidification/stabilization (S/S). • Pb had the highest S/S efficiency compared to Cu, Zn and Cd. • Presence of Pb 2 Cu (PO 4) 3 (OH)·4H 2 O promotes the S/S of Cu. • Heavy metals could increase the MgKPO 4 ·6H 2 O content and alter its morphology. Magnesium potassium phosphate cement (MKPC) is increasingly used in the solidification/stabilization (SS) of heavy metal (HM) pollutants. However, research on composite HM pollutants remains limited. In this study, four heavy metals (Pb/Zn/Cu/Cd) were individually and simultaneously introduced into MKPC systems with different magnesium/phosphorus (M/P) molar ratios. The introduction of HMs altered the extent of hydration and morphology of MgKPO 4 ·6H 2 O. Among the MKPC pastes, those with M/P = 2 and 3 had the highest HM solidification efficiency and strength, respectively. The HM solidification efficiency of all specimens exceeded 99 %. In samples with M/P = 3, the codoping of four HMs slightly increased the M/P ratio, thereby increasing MgKPO 4 ·6H 2 O content and enhancing strength. Pb could generate additional low-solubility precipitates, such as PbHPO 4 , Pb 3 (PO 4) 2 , Pb 5 (OH) (PO 4) 3 , and Pb (OH) 2 , which easily accumulated in pores and were encapsulated by MgKPO 4 ·6H 2 O, leading to the highest solidification efficiency of Pb by MKPC. Pb and Cu could also form the composite phosphate products Pb 2 Cu (PO 4) 3 (OH)·4H 2 O, thus promoting the S/S effect of Cu. Therefore, the use of MKPC with M/P ratio of 2–3 for the S/S of complex pollutants containing Pb and Cu is a promising approach. [ABSTRACT FROM AUTHOR]

• The risks of cardiovascular and respiratory diseases decline with PM 2.5 in Beijing. • Short periods of lockdown have little effect on long-term changes in health risks. • Ni, Cr, Pb, As, and BC in PM 2.5 show high carcinogenic risks in Beijing. • Health risks from traffic and biomass burning are more prominent in Beijing. • PM 2.5 mass concentration has decreased, but the risks of toxic components are still high. A comprehensive health risk assessment of PM 2.5 is meaningful to understand the current status and directions regarding further improving air quality from the perspective of human health. In this study, we evaluated the health risks of PM 2.5 as well as highly toxic inorganic components, including heavy metals (HMs) and black carbon (BC) based on long-term observations in Beijing from 2019 to 2021. Our results showed that the relative risks of chronic obstructive pulmonary disease, lung cancer, acute lower respiratory tract infection, ischemic heart disease, and stroke decreased by 4.07%-9.30% in 2020 and 2.12%-6.70% in 2021 compared with 2019. However, they were still at high levels ranging from 1.26 to 1.77, in particular, stroke showed the highest value in 2021. Mn had the highest hazard quotient (HQ , from 2.18 to 2.56) for adults from 2019 to 2021, while Ni, Cr, Pb, As, and BC showed high carcinogenic risks (CR > 1.0×10−6) for adults. The HQ values of Mn and As and the CR values of Pb and As showed constant or slight upwards trends during our observations, which is in contrast to the downward trends of other HMs and PM 2.5. Mn, Cr, and BC are crucial toxicants in PM 2.5. A significant shrink of southern region sourcesof HMs and BCshrank suggests the increased importance of local sources. Industry, dust, and biomass burning are the major contributors to the non-carcinogenic risks, while traffic emissions and industry are the dominant contributors to the carcinogenic risks in Beijing. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The refractory oxides of the W-residue formed a harmless slag after smelting with SKW. • Photovoltaic sawing waste was applied as a high-efficient silicothermic reductant. • Heavy metal oxides in W-residue were converted into high-value alloy phase. • An overall recovery rate of valuable metals of 91.7% was achieved. • The synergistic recovery mechanism of two industrial wastes was studied. Solid waste challenges in both the tungsten and photovoltaic industries present significant barriers to achieving carbon neutrality. This study introduces an innovative strategy for the efficient extraction of valuable metals from hazardous tungsten leaching residue (W-residue) by leveraging photovoltaic silicon kerf waste (SKW) as a silicothermic reducing agent. W-residue contains 26.2% valuable metal oxides (WO 3 , CoO, Nb 2 O 5 , and Ta 2 O 5) and other refractory oxides (SiO 2 , TiO 2 , etc.), while micron-sized SKW contains 91.9% Si with a surface oxide layer. The impact of SKW addition on the silicothermic reduction process for valuable metal oxides in W-residue was investigated. Incorporating SKW and Na 2 CO 3 flux enables valuable metal oxides from W-residue to be effectively reduced and enriched as a valuable alloy phase, with unreduced refractory oxides forming a harmless slag phase during the Na 2 O-SiO 2 -TiO 2 slag refining process. This process achieved an overall recovery yield of valuable metals of 91.7%, with individual recovery yields of W, Co, and Nb exceeding 90% with the addition of 8 wt.% SKW. This innovative approach not only achieves high-value recovery from W-residue and utilization of SKW but also minimizes environmental impact through an efficient and eco-friendly recycling pathway. The strategy contributes significantly to the establishment of a resource-efficient circular economy, wherein the recovered high-value alloy phase return to the tungsten supply chain, and the harmless slag phase become raw materials for microcrystalline glass production. [ABSTRACT FROM AUTHOR]

• The present study exerted heavy metal (Lead) accumulation and translocation capability of Withania somnifera shoots under lethal and non-lethal doses of Lead • In planta synthesis of Lead nanoparticles indicates that the presence specialized detoxification, sequestration and reduction mechanism in in vitro shoot cultures of Withania somnifera • Adsorption and translocation of Lead to aerial parts (stems and leaves) of the cultures was facilitated by liquid culture medium, and the addition of plant growth regulator (BAP), chelating agent (EDTA) and other mineral ions (Mg2+, K2+, Ca2+ and others) in the growth medium • Shoots exposed to non-lethal doses of Pb (800 µM) over prolonged period (12 days), significantly increased biomass and secondary metabolite (withanolides) production. Green synthesis of nanoparticles using biological extracts/live organisms has been the best substitute for chemical/physical synthesizing methods. Live plants can convert simple metal ions into metal nanoparticles using their intrinsic metabolic processes. In addition, medicinal plants with a hyperaccumulation potential also have high reduction potential which can be utilized for in planta synthesis of metal nanoparticles. Lead (Pb), a non-essential heavy metal, is known to stimulate various biological processes in plants at higher concentrations. Therefore, a medicinal plant with a hyperaccumulation potential was selected to investigate its potential for in planta reduction of Pb. In the present study, in vitro grown 45 days old Withania somnifera (L.) Dunal shoots were exposed to lead acetate (PbAC 2) at varying concentrations (acute: 300–4800 µM; chronic: 50–800 µM) for 12–48 h and 4–12 days, respectively. It revealed that cultures grown in 800 µM PbAC 2 for 12 days of exposure (C5) recorded significantly higher biomass (17.28 g) and increase in the divalent metal ions such as calcium from 1412 (control) to 1787 mg kg-1 (C5), potassium 21,109 (control) to 24,779 mg kg-1 (C5), and iron from 11 (control) to 82 mg kg-1 (C5), with lead (Pb) accumulation reaching up to 405 mg kg-1 (C5). Compared to the control shoots (0.783, 0.805 & 1.3 mg g-1), C5 shoots positively correlated with secondary metabolites namely withaferin A (3.14 mg g-1) and withanolide A (0.960 mg g-1) production and negatively with withanone (1.027 mg g-1). Also, C5 shoots had spherical shaped nanoparticles with a mean particle size of 25±10 nm which was then identified as lead nanoparticles (PbNPs). To our knowledge, the present study is the first of its kind where the in planta synthesis of PbNPs/PbONPs by in vitro shoot cultures of W. somnifera is reported along with accumulation of higher biomass and selective withanolides under Pb stress. [ABSTRACT FROM AUTHOR]

Phosphoric acid-activated geopolymer has become a promising ceramic material due to its superior thermal and mechanical properties. However, the gradual shortage of phosphate resources and the high price of phosphoric acid will be the key factors limiting the wide application of phosphoric acid-activated geopolymers. This paper developed a low-cost and low-carbon geopolymer non-sintered ceramics using industrial waste acid. The compressive strength of the prepared specimens can reach 32.2 MPa. The thermal gravimetric analysis indicated that the mass loss of the geopolymer remained almost unchanged in the temperature range between 400 and 1500 °C, indicating the geopolymer exhibited excellent thermal stability. Additionally, the infiltration test showed that the majority of the heavy metals could be solidified successfully with over 90% solidification efficiency, meaning the leaching of the heavy metals into the environment can be well controlled. Finally, the environmental and economic analysis showed that the carbon intensity (kg/m3/MPa) was reduced by 92.7% and 57.7% compared to cement paste and reported geopolymer. The cost intensity ($/m3/MPa) was negative due to the income of waste acid treatment, meaning that additional value benefit was added to the product. This paves a promising way for producing low-cost and low-carbon ceramic materials with excellent thermal and mechanical properties. [ABSTRACT FROM AUTHOR]

Shaerhu (SEH) coal is abundant in Xinjiang, China. The utilization of SEH suffers from severe ash deposition, slagging, and fouling problems due to its high-chlorine-alkaline characteristics. The co-combustion of high-alkaline coal and other type coals containing high Si/Al oxides has been proven to be a simple and effective method that will alleviate ash-related problems, but the risk of heavy metals (HMs) contamination in this process is nonnegligible. Hence, the volatilization rates and chemical speciation of Pb, Cu, and Zn in co-combusting SEH and a high Si/Al oxides coal, i.e., Yuanbaoshan (YBS) coal were investigated in this study. The results showed that the addition of SEH increased the volatilization rates of Pb, Cu, and Zn during the co-combustion at 800°C from 23.70%, 23.97%, and 34.98% to 82.31%, 30.01%, and 44.03%, respectively, and promoted the extractable state of Cu and Zn. In addition, the interaction between SEH and YBS inhibited the formation of the Pb residue state. SEM-EDS mapping results showed that compared to Zn and Cu, the signal intensity of Pb was extremely weak in regions where some of the Si and Al signal distributions overlap. The DFT results indicated that the O atoms of the metakaolin (Al 2 O 3 ⋅2SiO 2) (001) surface were better bound to the Zn and Cu than Pb atoms after adsorption of the chlorinated HMs. These results contribute to a better understanding of the effects of high-alkaline coal blending combustion on Pb, Cu, and Zn migration and transformation. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Heavy metals accumulate in biochar after contaminated peanut straw liquefaction. • Bioavailable fraction of heavy metals was converted to stable fraction in biochar. • Cd mobility was high in bio-oil, Zn and Cu were bound to unexchangeable fraction. • Leachability and phytoaccessibility of heavy metals were substantially reduced. • Heavy metal risk was reduced from medium and high risk to no and low risk. In this study, the speciation, leachability, phytoaccessibility, and environmental risks of heavy metals (Cd, Zn, and Cu) during liquefaction of contaminated peanut straw in ethanol at different temperatures (220, 260, 300, 340, and 380 °C) were comprehensively investigated. The results showed that elevated temperatures facilitated heavy metal accumulation in the biochar. The acid-soluble/exchangeable and reducible fraction percentages of heavy metals were substantially reduced in the biochar after liquefaction as the temperature increased, and the oxidizable fraction became the dominant heavy metal fraction, accounting for 44.14–78.67%. Furthermore, although an excessively high liquefaction temperature (380 °C) increased the residual fraction percentages of Zn and Cu, it was detrimental to Cd immobilization. The acid-soluble/exchangeable Cd in the contaminated peanut straw readily migrates to the bio-oil during liquefaction, with the highest concentration of 1.60 mg/kg at 260 °C liquefaction temperature, whereas Zn and Cu are predominantly bound to the unexchangeable fraction in the bio-oil. Liquefaction inhibited heavy metal leachability and phytoaccessibility in biochar, the lowest extraction rates of Cd, Zn, and Cu were 0.71%, 1.66% and 0.95% by diethylenetriamine pentaacetic acid, respectively. However, the leaching and extraction concentrations increased when the temperature was raised to 380 °C. Additionally, heavy metal risk was reduced from medium and high risk to no and low risk. In summary, liquefaction reduces heavy metal toxicity and the risks associated with contaminated peanut straw, and a temperature range of 300–340 °C for ethanol liquefaction can be considered optimal for stabilizing heavy metals. [ABSTRACT FROM AUTHOR]

[Display omitted] • BSFL has the strongest adsorption capacity for Zn and As in pig manure. • Addition of BC facilitates the migration of HMs into the BSFL body. • B. bacillus is beneficial for BSFL to accumulate more HMs. • The content of F1+F2 in the BSFL residue decreased due to the addition of BC. • HM speciation is affected by Firmicutes, Bacteroidetes, and Proteobacteria. During the conversion of pig manure by black soldier fly larvae (BSFL), the accumulation and speciation changes of heavy metals (HMs) have adverse effects on the environment. In this study, corn straw, rice straw, bamboo chips (BC), wood chips, and rice husk char were added to a bioconversion system to study the accumulation, migration, speciation changes, and microbial correlations of HMs. The results indicated that the addition of BC was most beneficial for the accumulation of HMs (47–72 %) in the BSFL body. In the BC group, the accumulation effect of the BSFL body on zinc (Zn) and arsenic (As) was the most evident (72 and 71 %, respectively). The results of linear fitting (R2 > 0.90) and redundancy analysis (RDA; 90 %) indicated that the bacterium Bacillaceae (Bacillus) was beneficial for increasing the larval weight (LW) of BSFL, and a higher LW accumulated HMs. The addition of BC helped reduce the total amount (6–51 %) of available states (weak acid extraction and reducible states) in the BSFL residue. The RDA results indicated that bacteria (55–92 %) affected the transformation of HM speciation. For example, Zn and cadmium were mainly affected by Firmicutes, whereas copper and chromium were affected by Bacteroidetes. Proteobacteria and Pseudomonas formosensis affected the conversion of lead and As. This study provides important insights into the adsorption of HMs from pig manure by BSFL. [ABSTRACT FROM AUTHOR]

Environmental pollution has gained negative attention in recent years. The pesticides and heavy metals are top list of environmental toxicants directly endangering the survival and development of Apis cerana cerana. Cyclin-dependent kinases (CDKs) are heteromeric serine/threonine kinases that participate in cell cycle regulation and have a vital role in pesticide and heavy metal stress in Apis cerana cerana. In this experiment, we filtered out CDK8 gene from Apis cerana cerana (AccCDK8) and investigated its functions of pesticide and heavy metals resistance. Sequence analysis indicated that AccCDK8 is highly homologous to multiple CDK8s and contains a highly conserved CDK active site sequence. Phylogenetic analysis showed that AmCDK8 and AccCDK8 were closely related evolutionarily in Apis mellifera. Transcriptome analysis revealed that AccCDK8 expression was differentially affected after exposure to pesticide and heavy metal stresses. This indicates that AccCDK8 has a significant role in the resistance of Apis cerana cerana to pesticide and heavy metal stresses. It has implications for studying the function of CDK in other insects in response to stress. [Display omitted] • Pesticides and heavy metals affect the survival of Apis cerana cerana. • CDK8 takes part in the oxidative stress response of Apis cerana cerana. • CDK8 is involved in the growth and reproduction of Apis cerana cerana. • AccCDK8 plays an important role in pesticide and heavy metals stresses. • We highlight the effects of some pesticides on the health of Apis cerana cerana. [ABSTRACT FROM AUTHOR]

The study aims to explore the environmental factors which activate accumulation abilities of Plantago lanceolata in the research area under strong anthropopressure resulting from the long-term pollution originating from copper mining-metallurgical activities in Southeastern Europe. Sampling was performed at the most endangered sites regarding its proximity to the major and/or secondary pollution sources, as well at the control site. The content of toxic elements (Al, Cu, Fe, Mn, Ni, Pb and Zn) was determined in the roots, leaves, stalks and flowers of P. lanceolata. The anthropogenic origin of environmental contamination was denoted through the high concentrations of Cu, Pb and Zn in the leaves of P. lanceolata , reaching toxic levels, combined with the enrichment of plant parts (Enrichment factor >2), especially with Cu (as well as with Al, Fe, Ni and Zn) in samples from the immediate proximity to the copper smelter or at the prevailing wind directions. Biomonitoring potential, assessed through the correlations between toxic element content, as well as the values of Enrichment factor, was indicated for roots (in the case of Cu), all the aboveground plant parts (Fe) and stalks (Zn). The results have shown that the contents of toxic elements in plant parts as well as phytoremediation of P. lanceolata were dependent on soil element content, soil physico-chemical properties and soil enzyme activities, which were regarded as the main environmental drivers affecting phytoremediation ability. The analysis of biological factors (bioconcentration, translocation and bioaccumulation factor) indicated exclusion strategy and possible usage of P. lanceolata in phytostabilization of Zn. The results indicated that the study area is 'environmental hotspot' with potential threat to human health due to the high levels of bioaccumulation of the investigated toxic elements in P. lanceolata parts. [Display omitted] [ABSTRACT FROM AUTHOR]

The present work studied electroplating wastewater treatment by the electro-oxidation (EO) method through a new Ti/TiO 2 -GO-SnO 2 electrode in a once-through continuous mode. The Ti/TiO 2 -GO-SnO 2 electrode was synthesized using an anodic oxidation technique and characterized by electrochemical characterizaftion. Response Surface Methodology (RSM) employing a Box-Behnken Design (BBD) model was utilized to optimize pH (3−7), current density (j = 16.72–50.16 mA/cm2), and time (t = 30–130 min) for removal of electroplating effluents and energy consumption. At the optimum condition, the values of the responses R 1 (% Cr(VI) removal), R 2 (% Zn removal), R 3 (% COD removal), and R 4 (energy consumption) were found to be 97.55%, 95.66%, 87.32%, and 14.97 kWh/m3, respectively. The effect of reactive species scavengers on removing electroplating effluents has been studied. The kinetics and cost analysis were also carried out under optimal conditions. Once-through continuous experiments were carried out at different flow rates to determine the viability of the process at industrial or pilot scale applications. The synthesized electrode proved highly reusable, maintaining durability even after sixty cycles of usage. Toxicity analysis showed that EO has the potential to detoxify electroplating effluents. The observed results confirm that the EO with Ti/TiO 2 -GO-SnO 2 electrode is low-cost and effective for removing electroplating effluents. [Display omitted] [ABSTRACT FROM AUTHOR]

Zinc leaching residue is the waste residue produced by the wet zinc extraction process, which cannot be effectively utilized due to its complex composition and the presence of toxic heavy metals. At this stage, a large amount of residue is piled up in the tailing storage, there is a waste of resources and the risk of environmental pollution. This paper introduced a study on the preparation of glass-ceramic in building materials from zinc leaching residue by the sintering method, using silica sand and albite as additives. It was found that the glass-ceramics prepared with zinc leaching residue incorporation of 70–75 % and sintering temperature in the range of 900–1000 °C exhibited excellent mechanical properties and stable chemical properties. The zinc leaching residue content and the sintering temperature together controlled the crystallization process and influenced the properties of the glass-ceramic. Increasing the zinc leaching residue content caused an increase in the content of non-bridging oxygen bonds in the glass-ceramic, which led to an increase in the degree of polymerization of the matrix and a decrease in the activation energy of the crystallization, which promoted the crystallization process. Higher temperatures provided more energy for the crystal crystallization reaction and facilitated the process. The glass-ceramics showed good solidification of heavy metals and compliance with the requirements for various heavy metals in the toxicity leaching test. The glass-ceramic made from zinc leaching residue eliminated the risk of heavy metals contamination and was a green, harmless, high-performance material that can be used in a wide range of fields. [ABSTRACT FROM AUTHOR]

Heavy metals enter our environment through diverse resources, causing harmful effects owing to their inherent toxicity and facile migration into aqueous medium, becoming an environmental challenge. Among technologies able to remove these contaminants, the adsorption process emerges as a promising application for water treatment. Herein, functionalized silica magnetic nanoparticles using inorganic and organic have been employed as adsorbents to remove environmental hazards from wastewater effectively. Magnetic silicate core-shell amino-functionalized (Fe 3 O 4 @SiO 2 -AP) nanocomposites were synthesised using acrylic acid (AA) and para-aminobenzoic acid (PABA) as dual copolymer for Cd (II) removal. The characterization analysis confirmed the formed crystal nanostructure and the copolymers were chemically introduced in the magnetic silicate core-shell nanoparticle. The Cd (II) adsorption results on (Fe 3 O 4 @SiO 2 -AP) nanocomposites achieved an impressive q max of 32.50 mg/g at pH 8, adsorbent dosage of 3 g/L, and Cd (II) concentration of 100 ppm. The laboratory-scale fixed-bed column showed the breakthrough curves are flow rate independent, achieving metal removal of 99% for 405 min, at pH 8, influent ion concentration of 100 ppm, flow rate of 5 mL/min, and 1 cm bed height. The Freundlich model was the most suitable for fitting equilibrium data (R2 adj = 0.981) indicating a multi-layer adsorption phenomenon in the heterogeneous surface sites of the (Fe 3 O 4 @SiO 2 -AP) nanocomposites. The pseudo-second-order model (R2 adj =0.999) confirms that the adsorption rate depends on nanocomposites active sites and occurs by chemical sorption mechanism. The reusability adsorption-desorption experiments slightly decreased from 97.5 to 86.7% in the sixth cycle stability, demonstrating the material stability. [Display omitted] • Sustainable magnetic silicate core-shell amino-functionalised nanocomposites were synthesised. • Multi-layered adsorption by Cd(II)-nanoparticles complex interactions, breakthrough curves are independent of flow rate. • Fe 3 O 4 @SiO 2 -AP recovered by an external magnetic field-driven. • Adsorption was driven by hydrogen bonding and coordination bonds. • High material stability and reusability after the sixth cycle was achieved. [ABSTRACT FROM AUTHOR]

Heavy metals are one of the core reasons for cancers and other disorders in humans and other organisms. Removal of heavy metal ions from contaminated resources is an expensive task. Replacement of deadly chemical adsorbents with biomaterials is an economic and eco-friendly approach for the treatment of contaminated water. The current study attempted to explore the biosorption potential of brown seaweed Stoechospermum marginatum to remove various heavy metal ions such as As, Zn, Cr and Pb. Structural analysis of the biomass before and after the biosorption was analyzed to check the structural characters and surface morphology of biomass. Functional groups responsible for the activity was studied by using the FTIR and it describes the presence of C-H bonds, carboxylic acid etc. which supports the biosorption. The surface morphology of biomass before and after biosorption was analyzed by SEM and XRD. SEM images show the vital change of biomass before and after biosorption. XRD result shows the crystalline phase of biomass. EDAX analysis on the metal bearing and raw biomass were conducted to check the localization of metals in the biomass. Influences of the parameters such as pH, time, initial metal concentrations, biomass concentration and temperature on the biosorption rate were also studied. The isotherm models such as Langmuir, Freundlich and Temkin was used to check the best fitting model. It was observed that, the present investigation fits with Langmuir model (32.154 mg/g) than the other models. Kinetic study indicates that the pseudo-second-order model suits for the reaction. The results showed that the biosorption was monolayer chemisorption. Moreover, the thermodynamic studies support the non-spontaneous reaction. The possibility of regeneration and reusability of heavy metal ions and biomass were also inspected. • Biosorption of heavy metal ions by brown seaweed were evaluated successfully. • FTIR, SEM, XRD and EDAX were applied to the biomass before and after biosorption. • Influence of various physicochemical parameters on the biosorption rate were studied. • Kinetic experiment on biosorption process were also carried out. • Stoechospermum marginatum supports the maximum adsorption of arsenic heavy metal. [ABSTRACT FROM AUTHOR]

• BW has strong acid resistance (pH ≥ 1). • BW selectively separates lead from complex heavy metal solutions. • The selective immobilization is due to its specific composite structure. The development of bio-adsorbents with highly selective immobilization properties for specific heavy metals is a great challenge, but has important application value. Biogenic whewellite (BW) with high selectivity for Pb(II) was synthesized by mineral microbial transformation. The selective immobilization properties and mechanism of BW for Pb(II) were analyzed by combining mineral characterization technology and batch adsorption research methods. The results indicated that BW can efficiently and selectively immobilize Pb(II) in single or composite heavy metal adsorption solutions, and the immobilized Pb(II) is difficult to desorb. BW undergoes monolayer adsorption on Pb(II), Q max ≈ 1073.17 mg/g. The immobilization of Pb(II) by BW is a physico-chemical adsorption process with spontaneous heat absorption and an accompanying increase in entropy. In addition, the sequestration of Pb(II) by BW remains around 756.99 mg/g even at pH = 1. The excellent selective immobilization properties of BW for Pb(II) are closely related to its smaller K sp , electrostatic repulsion effect, organic-inorganic composite structure, acid resistance and the formation of Pb(II) oxalate. This study provides beneficial information about the recycling of lead in acidic lead-containing wastewater and composite heavy metal contaminated water bodies. [Display omitted] [ABSTRACT FROM AUTHOR]

• The nosZ gene of N 2 O reductase determined by paddy soil tillage state. • The clade Ⅱ and Ⅰ nosZ gene was dominated in the tillage and fallow period, respectively. • Heavy-metal pollution inhibited the N 2 O emission while not affecting the genes' switch. • The genus Bradyhizobium most significantly regulated the N 2 O flux. Paddy soils are an important source of atmospheric nitrous oxide (N 2 O). However, numerous studies have focused on N 2 O production during the soil tillage period, neglecting the N 2 O production during the dry fallow period. In this study, we conducted an incubation experiment using the acetylene inhibition technique to investigate N 2 O emission and reduction rates of paddy soil profiles (0-1 m) from Guangdong Province and Jinlin Province in China, with different heavy-metal pollution levels. The abundance and community structures of denitrifying bacteria were determined via quantitative -PCR and Illumina MiSeq sequencing of nosZ, nirK , and nirS genes. Our results showed that the potential N 2 O emission rate, N 2 O production rate, and denitrification rate have decreased with increasing soil vertical depth and heavy-metal pollution. More importantly, we found that the functional gene type of N 2 O reductase switched with the tillage state of paddy soils, which clade Ⅱ nosZ genes were the dominant gene during the tillage period, while clade Ⅰ nosZ genes were the dominant gene during the dry fallow period. The heavy-metal pollution has less effect on the niche differentiation of the nosZ gene. The N 2 O emission rate was significantly regulated by the genus Bradyhizobium , which contains both N 2 O reductase and nitrite reductase genes. Our findings suggests that the nosZ gene of N 2 O reductase can significantly impact the N 2 O emission from paddy soils. [Display omitted] [ABSTRACT FROM AUTHOR]

Long-term deposition of atmospheric pollutants emitted from coal combustion and their effects on the eco-environment have been extensively studied around coal-fired power plants. However, the effects of coal-fired power plants on soil microbial communities have received little attention through atmospheric pollutant deposition and coal-stacking. Here, we collected the samples of power plant soils (PS), coal-stacking soils (CSS) and agricultural soils (AS) around three coal-fired power plants and background control soils (BG) in Huainan, a typical mineral resource-based city in East China, and investigated the microbial diversity and community structures through a high-throughput sequencing technique. Coal-stacking significantly increased (p < 0.05) the contents of total carbon, total nitrogen, total sulfur and Mo in the soils, whereas the deposition of atmospheric pollutants enhanced the levels of V, Cu, Zn and Pb. Proteobacteria, Actinobacteria, Thaumarchaeota, Thermoplasmata, Ascomycota and Basidiomycota were the dominant taxa in all soils. The bacterial community showed significant differences (p < 0.05) among PS, CSS, AS and BG, whereas archaeal and fungal communities showed significant differences (p < 0.01) according to soil samples around three coal-fired power plants. The predominant environmental variables affecting soil bacterial, archaeal and fungal communities were Mo-TN-TS, Cu-V-Mo, and organic matter (OM)-Mo, respectively. Certain soil microbial genera were closely related to multiple key factors associated with stacking coal and heavy metal deposition from power plants. This study provided useful insight into better understanding of the relationships between soil microbial communities and long-term disturbances from coal-fired power plants. [Display omitted] [ABSTRACT FROM AUTHOR]

• Microbial inoculants, (Rhizobium and two strains of AMF), were evaluated for their effectiveness in mitigating metal toxicity and reducing metal uptake in lentil plants. • Sewage sludge-amended soil adversely impacted lentil growth, leading to increased accumulation of heavy metals. • Microbial inoculants enhanced lentil growth and productivity, particularly under heavy metal stress. • Co application of microbial inoculants synergistically reduced heavy metal uptake in roots and shoots of lentil with more efficiency. • The findings suggest microbial inoculants could have practical applications for sustainable agriculture and efficient crop production. Reusing sewage sludge as a mode of nutrients and an organic amendment may be a viable choice for the appropriate treatment of organic waste. This study examined the impact of symbiotic microbes such as Rhizobium and two selected arbuscular mycorrhizal fungi (AMF), Funneliformis caledonius (Nicolson & Gerd.) and Glomus bagyarajii (Mehrotra), on the growth, photosynthetic pigments, biochemical content, microbial population, and heavy metal uptake in lentil plants grown in soil mixed with 20 % sewage sludge. Lentil seeds were inoculated with Rhizobium prior to sowing and with either of the AMF (Funneliformis caledonius or Glomus bagyarajii) in pots filled with soil-sewage sludge mixture. The results showed that the tested microbial inoculum enhanced the growth and productivity of lentil plants. Lentil plants inoculated with Rhizobium and AMF had better nodulation and root colonization, leading to an increase in the nitrogen, phosphorus and potassium (NPK) content and a decrease in the stress marker, proline, in plant parts. In addition, the inoculated microbes also improved the photosynthetic and biochemical contents of the plant. Lentil plants grown in sewage sludge-amended soil when inoculated with Rhizobium and either of AMF were found to be more effective in accumulating Cd, Cr, Pb, Ni, and Zn in the roots, while restricting their translocation to the above-ground parts of the plant, thereby improving plant health. Overall, the study outcomes provide evidence that Rhizobium and AMF have the potential to tolerate heavy metal stress caused by the addition of sewage sludge to soil, which has important implications for sustainable agriculture practices. The study also highlights the importance of microbial inoculants, such as Rhizobium and AMF in enhancing growth and yield, particularly under heavy metal stress in economically important lentil. [ABSTRACT FROM AUTHOR]

• Heavy metal tolerant and PGPR rhizobacteria (Bacillus cereus, Bacillus safensis, Bacillus pumilus, Serratia marcescens, Lelliottia amnigena, Pseudomonas koreensis and Klebsiella variicola) isolated from Musa rhizosphere growing in coal mining area. • Inoculation of the PGPR consortia in the Brassica sp. and Helianthus annuus growing in Cd/Cu contaminated soil has improved its tolerance to these heavy metals over the control. • PGPR can be used for the bioremediation of the contaminated soil. In soils polluted with heavy metals, plant growth promoting rhizobacteria (PGPR) with heavy metal tolerance can aid plants to adapt to heavy metal contaminated conditions. Heavy metal tolerant rhizobacteria were isolated from Musa rhizosphere growing the Tsurang Riverbank, Nagaland, India, a coal mining area. A total of 26 bacterial isolates/strains were tested for heavy metals and salt tolerance and some growth-promoting traits like IAA, siderophore production and phosphate solubilisation. Of the 26 strains, 7 strains (TSU1, TSU11, TSU12, TSU3, TSU4, TSU7, and TSU8) supported better plant growth. Different isolates displayed variable heavy metal tolerance (30 to 8070 μg/ml). Strains TSU8 and TSU4 exhibited the highest salt tolerance (12 %). Based on the 16S rRNA sequencing, the isolates were identified as TSU3 (Bacillus cereus) (OQ547230), TSU4 (Bacillus safensis) (OQ547231), TSU8 (Bacillus pumilus) (OQ547232), TSU11 (Klebsiella variicola) (OQ947091), TSU12 (Lelliottia amnigena) (OQ947097), TSU7 (Pseudomonas koreensis) (OQ947088) and TSU1 (Serratia marcescens) (OQ726408). A successful consortium of bacterial isolates was formulated and inoculated on Brassica juncea and Helianthus annuus with heavy metal Cd/Cu (150 µgml−1) in the potted soil. This consortium improved growth performance significantly in both fresh and dry weight basis. In B. juncea, enhancement in root length and weight were recorded by 53 and 93 % respectively against control, while, fresh weight of shoot was improved by 72 % on soil adjunct with PGPR and 67 % with PGPR in heavy metal contaminated condition. Similar trend was also registered on dry weight basis. Whereas, PGPR consortia treated H. annuus registered increased shoot and root lengths both fresh and dry weight basis. This consortium with these seven bacterial isolates may contribute to microbe assisted phytoremediation under heavy metal polluted area. [ABSTRACT FROM AUTHOR]

This study aimed to assess the associations between blood heavy metal concentrations and hearing loss. This was a systematic review and meta-analysis. A comprehensive literature search was performed using Embase, PubMed, Web of Science, Cochrane Library, China National Knowledge Infrastructure, Chinese Biomedical Literature, Wanfang and Weipu databases. Ten studies were included, and a random or fixed-effects model was used for the meta-analysis. Review Manager 5.4 software was used for data synthesis, and Stata 15.1 software was used for the publication bias and sensitivity analyses. Blood lead concentrations were significantly and substantially associated with hearing loss (mean difference (MD) = 1.14; 95% confidence interval [CI] = 0.03, 2.26; P = 0.04; I 2 = 81%), and iron deficiency was significantly related to hearing loss (MD = −0.42; 95% CI = −0.66, −0.18; P = 0.12; I 2 = 60%). These results suggest an association between blood heavy metal concentrations and hearing loss. However, there were limitations: confounding factors, lack of description for the specific methods of blinding and independent verification of case definition, limited sample size, Chinese publications comprising half of the primary data and the lack of assessment of the relationship between different blood heavy metal concentrations and the severity of hearing loss. Therefore, larger and well-designed prospective cohort studies are required for further exploration. [ABSTRACT FROM AUTHOR]

Phosphorus (P), as a crucial resource, has attracted more attention for its recycling. Products from hydrothermal reaction of sewage sludge (SS), represent promising sources for efficient P recovery. This work systematically summarizes reaction mechanisms of SS hydrothermal reactions and corresponding distribution, migration, and morphological transformation pathways of P during reactions. The formation of hydrochar is mainly attributed to the polymerization, aromatization, and condensation of remarkably reactive intermediates generated through the degradation of biopolymers in SS, as well as the solid-solid conversion of part of lignin and the precipitation of insoluble humic substances. P in SS is mostly concentrated in solid-phase products (hydrochar) after hydrothermal reaction. Orthophosphate is the dominant P species in hydrochar. The distribution and migration transformation pathways of P are notably influenced by reaction conditions (i.e., reaction temperature, reaction time, initial pH and additives). The reaction time had a small effect on P conversion. Wet chemical extraction is widely used to extract P from hydrochar. The P extraction efficiency of acid extraction is higher than that of alkaline extraction. However, the precipitation of heavy metals in hydrochar limits industrial application of acid leaching. Ultimately, some prospects for the optimization of the P recovery process are put forward. [Display omitted] [ABSTRACT FROM AUTHOR]

• Current and emerging photovoltaic modules may include small amounts of toxics. • Global toxicity characterization policies for photovoltaic devices are compared. • Sampling approach, particle size, and methods cause leachate result variability. • Limitations of current assessment procedures and regulations are disclosed. Environmental management of solar photovoltaic (PV) modules is attracting attention as a growing number of field-operated PV modules approach end of life (EoL). PV modules may contain small amounts of toxic metals, and the procedures for assessing and regulating the toxic metal content and release of such materials at EoL differ widely across nations. This paper provides an overview of the metal composition of PV modules and common procedures for toxicity assessment through extensive research and review of technical literature and legislative documents. This review focuses on three primary aspects: first, it explores the distribution of toxic elements within current and emerging PV module designs, with a specific focus on obtaining representative samples for proportional toxicity testing within different module laminate areas. Second, it examines a sampling standard and the diverse toxicity testing methods and regulations employed in various regions, encompassing standards like the Environmental Protection Agency (EPA) Test Method 1311 (Toxicity Characteristic Leaching Procedure, TCLP) in the U.S., Restriction of Hazardous Substances (RoHS) in Europe, and the Waste Extraction Test (WET) in California. Third, the review examines the sources of variability in toxicity testing outcomes, including techniques for securing homogeneous samples from non-uniform PV modules, selecting particle sizes representative of landfill conditions in extracted samples, determining appropriate leachate characteristics such as leaching agents and pH levels, and considering factors like test duration and temperatures. In summary, this review summarizes relevant regulations and offers a comprehensive overview of the strengths and limitations associated with several toxicity assessment procedures currently in practice. [ABSTRACT FROM AUTHOR]

• Large column and water tank were used to study the properties of particle layer. • Salt-resistant bentonite showed excellent adsorption capability for heavy metals. • Particle layer showed excellent properties under different depths of seawater. • Particle layer performed well under waste loaded seawater condition. The complex seabed conditions and ocean environment pose significant challenges to the material selection and construction of bottom liners for offshore final disposal sites. To overcome the challenges, this study proposed a novel isolation particle layer for offshore final disposal sites. The isolation particle was composed by salt-resistant bentonite coating material and cement core material (D10 was 10 mm in core diameter and 2 mm in coating thickness; D20 was 20 mm and 4 mm). Upon immersion in artificial seawater, the isolation particles underwent expansion, leading to the formation of the novel isolation particle layers with low hydraulic conductivity less than 1 × 10-7 cm/s and adsorption of heavy metals in bentonite interlayers. Large column tests showed that both D10 and D20 isolation particle layers exhibited remarkable swelling capacity and low hydraulic conductivity (4.3 × 10-9 cm/s and 2.6 × 10-8 cm/s) under 3 m seawater pressure. During one year of observation, water tank test demonstrated that both isolation particle layers displayed remarkable stability and low hydraulic conductivity of 2.73 × 10-10 cm/s and 8.36 × 10-10 cm/s with load. The maximum adsorption capacities of salt-resistant bentonite were 123.55 mg/g for Pb2+, 60.29 mg/g for Cd2+ and 54.22 mg/g for Cu2+. Both isolation particle layers exhibited a high removal rate of over 95 % for heavy metals in water tank tests. The large-scale laboratory tests indicated the significant potential of the novel isolation particle layer for offshore final disposal sites. Subsequently, a testing ocean site will be selected to further investigate its practical engineering performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • First generation PV technology competes with new generations, yet dominating. • Global trends for silicon-based PV recycling are overviewed. • Recovered products are utilized as secondary raw material of the PV industry. • Current challenges are underlined with appropriate suggestions. With the rapid deployment of renewable energy using photovoltaic (PV) panels, the sustainable management of decommissioned PV modules has become challenging. Decommissioned modules contain heavy metals, such as copper, cadmium, and lead, and hazardous polymer substances, such as ethylene vinyl acetate, polyethylene terephthalate, and polyvinylidene fluoride, which can pose a serious threat to the environment if disposed in a landfill. In addition, the low concentration value of critical metals, such as silver, indium, and tellurium, can also be lost. In this context, recycling decommissioned PV panels can be useful to resource recovery of valuable metals while lowering environmental stress. However, the lower share of PV modules and the prolonged life of 25–30 years compared to other waste volumes (e.g., electronic waste) hinder the progress in this direction. In contrast, reaching the end-of-life of the deployed first-generation PV panels is creating attraction toward the recycling of decommissioned modules. Henceforth, exploring the commercial viability of PV recycling necessitates a review of the methodologies that have been investigated on a laboratory scale and have the potential to be up-scaled. In this review, the recent trends in various PV-recycling steps, including frame disassembly, delamination, metal extraction, and recovery, are underlined while the associated problems are determined to suggest the required improvements in future technology. Furthermore, the environmental and economic feasibility of a few techniques are discussed to establish the viability of the recycling process. This review contributes to formulating PV waste management strategies and providing future research directions. [ABSTRACT FROM AUTHOR]

• In-situ formation of MgFe 2 O 4 enhancing the dehydration and decarboxylation of SM. • Stabilization of HMs was obviously increased after MgFe 2 O 4 modified HTC. • P retention rate reached 88% due to the decrease of soluble and exchangeable P. • MFHCs exhibited high Pb(II) and Cu(II) adsorption capacity without any HMs leaching. Hydrothermal carbonization is an efficient technique for the disposal of livestock manure, enabling its harmless treatment, quantity reduction, and resourceful utilization. Co-hydrothermal of modified materials facilitates the production of more valuable carbonaceous materials. However, further exploration is needed to understand their potential impact on the environmental risks associated with livestock manure disposal and the application of products derived from it. Therefore, the carbonization degree, heavy metals stabilization, and phosphorus retention during the hydrothermal treatment of swine manure were systematically investigated in this study under the influence of in-situ formed MgFe 2 O 4. The results revealed that the in-situ formation of MgFe 2 O 4 improved the dehydration and decarboxylation of organic components in swine manure, thereby improving its carbonization degree. Furthermore, both hydrothermal carbonization and MgFe 2 O 4 modified hydrothermal carbonization resulted in an enhanced stabilization of heavy metals, leading to a significant reduction in their soluble/exchangeable fraction and reducible fraction. Phosphorus was predominantly retained in the hydrochars, with the highest retention rate reaching 88%, attributed to the significant decrease in soluble and exchangeable phosphorus fractions facilitated by the in-situ formation of MgFe 2 O 4. Moreover, MgFe 2 O 4 modified hydrochars exhibited remarkable adsorption capacity for Pb(II) and Cu(II) without any leaching of heavy metals. Overall, the findings indicated that the in-situ formation of MgFe 2 O 4 positively influenced the hydrothermal of swine manure, improving certain economic benefits in its practical application. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a prevalent heavy metal contaminant that can cause centrosome amplification (CA) and cancer. Since CA can initiate tumorigenesis, it is plausible that cadmium initiates tumorigenesis via CA. The present study investigated the signaling pathways underlying CA by Cd. Our findings confirmed that sub-toxic concentrations of Cd could induce CA in the HCT116 colon cancer cells, and revealed that reactive oxygen species (ROS), GCLM, CCDC85C and PLK4 were the signaling molecules that formed a pathway of ROS-GCLM-CCDC85C-PLK4. Cd not only increased the protein levels of CCDC85C and PLK4, but also promoted their distribution to the centrosomes. Molecular docking analysis revealed that CCDC85C and PLK4 had the binding potential. Indeed, antibodies against CCDC85C and PLK4 were able to pull down PLK4 and CCDC85C, respectively. Knockdown of CCDC85C decreased the Cd-promoted centrosomal distribution of PLK4. Similarly, knockdown of PLK4 reduced the centrosomal distribution of CCDC85C. Our results suggest that Cd activates ROS-GCLM pathway that triggers the expression of and binding between CCDC85C and PLK4, and promotes the translocation of CCDC85C-PLK4 complex to the centrosomes, which eventually leads to CA. • GCLM and CCDC85C are new players for centrosome amplification. • CCDC85C binds with PLK4 and contributes to its localization on the centrosome. • Cd promotes CA through the ROS-GCLM-CCDC85C-PLK4 pathway. [ABSTRACT FROM AUTHOR]

(1) Cr and Mn were heavily contaminated; Ni and Zn were moderately contaminated. (2) The semi-variogram and ordinary kriging revealed the spatial distribution of HMs. (3) Soil pH was the main factor affecting the chemical fractions of HMs. The accumulation of coal gangue (CG) from coal mining is an important source of heavy metals (HMs) in soil. Its spatial distribution and environment risk assessment are extremely important for the management and remediation of HMs. Eighty soil samples were collected from the high-sulfur CG site in northern China and analyzed for six HMs. The results showed that the soil was heavily contaminated by Mn, Cr and Ni based on the Nemerow index, and posed seriously ecological risk depended on the geo-accumulation index, potential ecological risk index and risk assessment code. The semi-variogram model and ordinary kriging interpolation accurately portrayed the spatial distribution of HMs. Fe, Mn, and Cr were distributed by band diffusion, Ni was distributed by core, the distribution of Cu had obvious patchiness and Zn was more uniform. The spatial autocorrelation indicated that all HMs had strong spatial heterogeneity. The BCR sequential extraction was employed to qualify the geochemical fractions of HMs. The data indicated that Fe and Cr were dominated by residual fraction; Cu, Ni and Zn were dominated by reducible and oxidizable fractions; Mn was dominated by reducible and acid-extractable (25.38%-44.67%) fractions. Pearson correlation analysis showed that pH was the main control factor affecting the non-residue fractions of HMs. Therefore, acid production from high sulfur CG reduced soil pH by 2-3, which indirectly promoted the activity of HMs. Finally, the conceptual model of HMs contamination at the CG site was proposed, which can be useful for the development of ecological remediation strategies. [Display omitted] [ABSTRACT FROM AUTHOR]

Heavy metals from mica waste not only deteriorate the soil quality but also results in the uptake of metals in the crop. The present investigation was conducted to evaluate the effects of different fractions of metals on the uptake in rice, soil microbial and biochemical properties in mica waste-contaminated soils of Jharkhand, India. From each active mine, soil samples were randomly collected at distances of < 50 m (zone 1), 50–100 m (zone 2), and >100 m (zone 3). Sequential metal extraction was used to determine the fractions of different metals (nickel (Ni), cadmium (Cd), chromium (Cr) and lead (Pb)) including water-soluble (Ws) and exchangeable metals (Ex), carbonate-bound metals (CBD), Fe/Mn oxide (OXD) bound metals, organically bound metals (ORG), and residues (RS). The Ni, Cr, Cd and Pb in rice grain were 0.83±0.41, 0.41±0.19, 0.21±0.14 and 0.17±0.08 mg/kg respectively. From the variable importance plot of the random forest (RF) algorithm, the Ws fraction of Ni, Cr and Cd and Ex fraction of Pb was the most important predictor for rice grain metal content. Further, the partial dependence plots (PDP) give us an insight into the role of the two most important metal fractions on rice grain metal content. The microbial and enzyme activity was significantly and negatively correlated with Ws and Ex metal fractions, indicating that water-soluble and exchangeable fractions exert a strong inhibitory effect on the soil microbiological parameters and enzyme activities. [Display omitted] [ABSTRACT FROM AUTHOR]

• Heavy metal concentrations in the SPM were high during the dry period than in the rains. • The volumetric levels of SPM depicted the influence of oceanic waters. • Calculated Toxic Risk Index indicated low toxic risk to the benthos living in the lagoon. • The mean –ERM- Quotient denoted 9% probability of toxicity to the biota. The present study aimed to evaluate multi-element concentrations (Al, As, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sr) in suspended particulate material (SPM) collected from Ensenada de La Paz (ELP) lagoon, Baja California Sur, Mexico in two different periods (September and May) to comprehend their origin, geochemical behavior, mass transfer and associated ecotoxicological risks. The 24 hr variation coefficient of volumetric SPM levels were found to be 51.7% in September and 40.5% in May, signifying the effects of oceanic waters. The calculated enrichment factor (EF) values for all the studied elements were of higher magnitude because of the high surface area and oxide nature of SPM, and in this study, Mo had the highest EF of 46.77 probably due to its origin from continental weathering. From the ecotoxicological perspective, the integrated toxic risk index revealed low toxic risk to the benthic community. However, the mean-ERM-Quotient calculated using the particulate concentrations of As, Cd, Cr, Cu, Ni, Pb indicated 9% probability of toxicity to biota. The comprehensive geochemical and ecotoxicological assessment of particulate metal concentrations in the ELP lagoon signify low to moderate contamination. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Waste € Banknotes (W€B) is a promising substrate for AD valorization. • W€B methane yield, raw and pretreated, was 297 and 334 NmL CH 4 g VS-1, respectively. • Heavy metals were not a cause of inhibition. • The physical pretreatment increases the maximum methane production rate by 22.4% • Logistic kinetic model showed less than a 5% deviation from experimental values. The European Central Bank is striving to find environmentally friendly alternative methods of waste disposal. In 2020, it decided to end the disposal of Waste Euro Banknotes (W€B) in landfills and planned to use them for recycling and/or energy recovery. Despite being recognized as an effective tool in a circular economy model, there are no reported studies on the use of W€B as a substrate in anaerobic digestion (AD). Thus, the aim of this research was to assess the viability of W€B to be converted into high-value-added energy products (mainly methane) through AD. W€B (€10 and €20 denominations) provided by the Bank of Spain were used. Biochemical methane potential (BMP) tests of pre-treated (grinded) and untreated W€B were assessed at mesophilic temperature. The ultimate methane yield was considerably higher for pre-treated W€B (334 ± 23 NmL CH 4 g VS-1 added) than for untreated W€B (297 ± 14 NmL CH 4 g VS-1 added). The Logistic or Sigmoidal kinetic model adequately fit the experimental data and allowed for obtaining the kinetic parameters of each case studied. In this sense, an increase of 22.4 % in the maximum methane production rate (R max) was observed for the pre-treated W€B (52.5 ± 0.9 mL CH 4 (g VS·d)-1 compared to the untreated W€B (16.2 ± 1.8 mL CH 4 (g VS·d)-1). According to the obtained results, AD may be a good alternative for the energetic valorization and recycling of W€B. [ABSTRACT FROM AUTHOR]

• Production activities caused strong spatial heterogeneity of heavy metal(loid)s. • The migration of heavy metal(loid)s in soils was ordered as cd > zn > pb > as. • Arsenic existed in soil with high total contents but weakly migrated. Heavy metal(loid)s contamination is a constant issue at smelting sites. It is essential to investigate the spatial distribution and migration characteristics of heavy metal(loid)s in the soil for environmental management and remediation strategies of non-ferrous smelting sites. In this study, 203 soil samples from 57 sites were collected in a typical lead smelting site. The findings demonstrated that there were significant Pb, Zn, Cd, and As contamination in soil samples. The spatial distribution of heavy metal(loid)s showed strong spatial heterogeneity, the contaminated soil areas of Pb, As, Cd, and Zn were 99.5%, 98.9%, 85.3%, and 72.4%, respectively. Pb, Cd, and As contamination of the soil reached a depth of 5 m, which migrated from the surface to deep soil layers. The leaching contents of Zn, Pb, and As decreased obviously in 3-4 m soil layer, but the leaching content of Cd was still high, which indicated the high migration of Cd. With the increase of depth, the proportion of acid soluble fraction of heavy metal(loid)s decreased, and the residual fraction increased. The acid soluble fraction of Cd accounted for a higher proportion, and As mainly existed in reducible and residual fractions in soil. According to the calculation of the migration factor, the migration of heavy metal(loid)s in soils were ordered as Cd > Zn > Pb > As. The outcomes are advantageous for risk reduction and site remediation for non-ferrous metal smelting sites. [Display omitted] [ABSTRACT FROM AUTHOR]

• Eddy leaching technique was developed to treat heavy metal-contaminated soil. • Concentration of heavy metals in soil reduced as particle size increased. • Highest separation efficiency of hydrocyclone was 84.7%. • Enhanced desorption of heavy metals by eddy leaching compared to OAPE. An eddy deep leaching technology was developed in this paper to address the challenge of treating heavy metal contaminants in industrial mining areas. The desorption effect of As, Cd, Sb and Pb was investigated utilizing chemical leaching and physical eddy techniques. It was found that the heavy metals concentration increased with decreasing particle size. The highest proportion of Cd in the form distribution of soil was in the bound to iron and manganese oxides, while the maximum proportion of As, Sb and Pb were in the residual. The optimal solid-liquid ratio of the hydrocyclone was 1:20, and the corresponding separation efficiency and flow rate were 84.7% and 1.76 m3/hr, respectively. The grade efficiency of soil particle separation increases with particle size and exceeds 99% for particles above 1,000 µm. Leaching experiments have revealed that oxalic acid (OA) and a combination of oxalic acid and EDTA (OAPE) were more efficient than citric acid (CA) and a combination of citric acid and EDTA (CAPE) for the desorption of heavy metals, respectively. The comparison of OAPE and eddy leaching found that the latter improved the desorption efficiency by 9.4%, 7.5%, 7.2% and 7.8% for As, Cd, Sb and Pb compared to the former, respectively. The results demonstrated that the eddy leaching technique could further enhance the desorption efficiency of heavy metals. It is expected to provide technical support for soil remediation with reduced usage of leaching agents. [Display omitted] [ABSTRACT FROM AUTHOR]