Search Results (202)

Schwertmannite (Sch) is a widespread iron oxyhydroxysulfate mineral in acid mine drainage (AMD) systems, and its transformation strongly influences the environmental fate of chromium (Cr). However, the role of Ca(II), which is commonly introduced during alkaline neutralization of AMD, in regulating the transformation of Cr(VI)-adsorbed schwertmannite (Cr-Sch) and subsequent Cr redistribution remains insufficiently understood. In this study, transformation experiments were conducted under various pH conditions (3.0, 7.0, and 10.0) to investigate the effects of Ca(II) speciation on mineral transformation and Cr behavior. The results demonstrated that the transformation of Cr-Sch was predominantly pH-dependent. Under acidic conditions, Cr-Sch transformed into goethite via dissolution–recrystallization, resulting in transient Cr release followed by partial refixation. The presence of Ca(II) exerted only a minor influence due to weak interactions between Ca²⁺ and positively charged mineral surfaces. Under alkaline conditions, Cr-Sch preferentially transformed into hematite through dehydroxylation and cation rearrangement, leading to the sustained release of adsorbed Cr(VI). In contrast, Ca(II) predominantly precipitated as CaCO₃ precipitate (calcite, aragonite, and vaterite) under alkaline conditions, which coated mineral surfaces and inhibited phase transformation and Cr release. These findings reveal that Ca(II) regulates Cr redistribution primarily through pH-dependent speciation and mineral–surface interactions, highlighting coupled geochemical processes governing iron mineral transformation and contaminant mobility in AMD environments. This study provides mechanistic insights for predicting Cr behavior and optimizing alkaline remediation strategies in mining-impacted systems. Full article

Cobalt-based catalysts are promising for propane dehydrogenation (PDH), but their practical application is hindered by limited propylene yields, rapid deactivation, and an incomplete understanding of the catalytically relevant Co species. Here, alkaline treatment was used to increase the density of silanol defects on Silicalite-1, thereby creating abundant anchoring sites for highly dispersed Co species. The resulting Co/Silicalite-1 catalyst achieved 45% propane conversion, 96% propylene selectivity, and stable operation over 60 h on stream (k_d = 0.005 h⁻¹). Combined characterization indicates that silanol defects stabilize highly dispersed, defect-anchored Co species that are responsible for the superior PDH performance. By contrast, supports with lower silanol defect densities favor aggregated CoO_x/Co₃O₄-like species, which are less selective for PDH, more susceptible to reduction to metallic Co under reducing conditions, and more prone to cracking and coke formation. These findings reveal a strong correlation between silanol defect density, Co speciation, and catalytic performance, offering mechanistic insights and design principles for the development of efficient PDH catalysts. Full article

Magnetic biochar (MBC), a magnetically responsive soil amendment, has attracted considerable attention due to its efficient magnetic separation capability and strong potential for remediating heavy metal-contaminated soils. Despite extensive research, a comprehensive evaluation of its raw materials, synthesis routes, performance-influencing factors, removal mechanisms, and microbial interactions remains limited. This review systematically examines biomass feedstocks and magnetic precursors used in MBC production and critically evaluates preparation methods, including hydrothermal carbonization, co-precipitation, ball milling, microwave pyrolysis, and impregnation–pyrolysis. Key factors affecting heavy metal removal—such as metal speciation, pyrolysis temperature, soil properties, dosage, and feedstock type—are discussed in detail. The primary immobilization mechanisms, including redox reactions, surface and co-precipitation, ion exchange, functional group complexation, physical adsorption, π–π interactions, and electrostatic attraction, are comprehensively analyzed. Furthermore, the interactions between MBC, soil physicochemical parameters, and microbial communities are evaluated to assess ecotoxicological implications. Finally, we provide valuable recommendations for the future direction of magnetic biochar research to advance its application in heavy metal removal from soil. Full article

Lead contamination in urban soils, primarily from deteriorating lead-based paint, poses a significant health risk in the United States. These soils often serve as major sources of exposure, making them critical targets for remediation efforts. To guide such strategies, preliminary risk assessments are necessary to evaluate lead bioaccessibility in the soil and identify key soil properties influencing lead speciation. In this study, a novel machine learning approach was co-developed with an artificial intelligence assistant, Claude Sonnet, developed by Anthropic, to design a predictive model that overcomes the difficulties of conducting experimental bioaccessibility models. Data was compiled from published sources (n = 640), as well as an internal analysis of soils sampled across three large cities in the United States (n = 30), to use as a validation model. While our final model’s prediction accuracy was good (R² = 0.95), it initially did not perform as expected on our internal dataset, indicating a fundamental domain shift. Further analysis revealed complications with outliers, data availability, and data consistency that resulted in poor performance. When optimization was applied to the validation model, our final prediction accuracy improved (R² = 0.84). Here, we conclude the importance of data availability and consistency in heavy-metal soil bioaccessibility studies to build a generalizable predictive model. Full article

Acoustic divergence is widely recognized as a key driver of speciation and niche differentiation in vocal animals. In echolocating horseshoe bats (Rhinolophus), the larynx is specialized for producing high-duty-cycle signals used in foraging, navigation, and species recognition. While the ecological role of echolocation is established, the molecular mechanisms regulating laryngeal frequency remain unclear. We compared the laryngeal transcriptomes of three closely related, sympatric Rhinolophus species with distinct resting frequencies (RFs): R. episcopus (~46 kHz), R. siamensis (~66 kHz), and R. osgoodi (~85 kHz). This comparison identified 511 differentially expressed genes. High-frequency species upregulated genes involved in cytoskeletal dynamics and muscle contraction, such as cell adhesion molecules and motor proteins, while low-frequency species upregulated genes related to cellular homeostasis and metabolic maintenance. Weighted gene co-expression network analysis revealed two RF-correlated modules: a high-frequency module enriched in aerobic respiration and carbon metabolism and a low-frequency module enriched in lipid metabolism. Protein–protein interaction analysis identified ACTC1, vital for muscle contraction, as a hub gene. Evolutionary analysis showed that ACTC1 is highly conserved, with no significant positive selection, indicating that transcriptional regulation, rather than coding-sequence divergence, is the primary driver of the observed functional differences. These findings suggest that RF variation likely results from transcriptional remodeling in laryngeal superfast muscles. This study provides the first transcriptomic evidence linking laryngeal gene expression with acoustic divergence and offers new insights into the genetic basis of bat echolocation. Full article

Co-pyrolysis of sludge and plastics has gradually emerged as a crucial technical approach for waste reduction and resource recovery. This study develops high-precision, interpretable prediction models and quantifies the contributions of core risk factors to environmental risks. Based on the experimental datasets from 2015 to 2025, which include operational parameters and eight potential toxic elements (PTEs) with four chemical speciation fractions: acid-soluble/exchangeable (F1), reducible (F2), oxidizable (F3), and residual (F4), we constructed six machine learning models. Based on the experimental datasets from 2015 to 2025, which include operational parameters and eight potential toxic elements (PTEs) chemical speciation (F1–F4), we constructed six machine learning models. Feature importance analysis and Shapley Additive Explanation (SHAP) analysis were employed to identify core risk factors and interpret the model’s decision logic. Results indicate that XGBoost, Random Forest and CatBoost outperform other models, achieving test accuracies of 0.94, 0.92, and 0.90, with weighted F1-Scores of 0.94, 0.92, and 0.90, respectively. Feature importance highlights the most important features for the six different models, with Cd-F4, As-F1, and Cu-F4 contributing most significantly to the model predictions. SHAP analysis quantified the contributions of each feature to the model predictions, verified Cd-F4 as the primary risk discriminant, and further revealed that F1 and F4 of PTEs are key factors in distinguishing risk levels. This study proposes an interpretable machine learning framework, providing a theoretical basis for the optimization of the sludge and plastic co-pyrolysis process and the assessment of potential risks. Full article

Decarbonizing energy production is critical to slowing the effects of climate change and furthering global sustainability. Progress is often gauged via carbon dioxide (CO₂) emissions; however, sources of CO₂ vary beyond combustion, presenting a significant challenge to accurate tracking due to these various sources and sinks and the ubiquitous nature of CO₂ in the atmosphere. Nitrogen oxide (NO_X) emissions have previously been proposed as a surrogate for tracking sustainability, as they are primarily released from combustion processes. Facility-level data from Canada’s National Pollutant Release Inventory and Greenhouse Gas Reporting Program over a six-year period is used to assess the correlation between NO_X and CO₂ emissions from integrated facilities across Canada. Combustion-related CO₂ emissions accounting for approximately 94% of Canadian industrial emissions are examined, targeting eleven industries which together encompass over 90% of combustion emissions. Multiple linear regressions (MLRs) on each industry correlating NO_X, CO₂, and the inventory methods used (i.e., emission factors (EFs), source monitoring, mass balance, engineering estimates, and speciation) show R² values ranging from 0.81 to 0.96 for all but one industry. Several industries indicate that the methods used to calculate emissions influence the correlation of CO₂ to NO_X, highlighting issues in the current inventory techniques. The NO_X-to-CO₂ ratios calculated for the integrated facilities are similar to the ratios of the published main process-level EFs for NO_X to CO₂ (where available). These MLR models on NO_X could be used to predict CO₂ emissions with relative ease and accuracy in other jurisdictions, thereby simplifying large-scale emission inventory compilation while tracking sustainability. Full article

The hydroformylation of alkenylbenzenes remains insufficiently defined, despite the relevance of these substrates as biomass-derived aromatic feedstocks within sustainable chemical transformations. In this work, we present an experimental (catalytic and kinetic) study of their conversion into aldehydes under rhodium-phosphine catalysis, using complexes bearing mono-, bi- and tridentate phosphine ligands, [Rh(H)(CO)₂(PPh₃)₂], [Rh(H)(CO)(triphos)] and [Rh(H)(CO)₂(dppe)], under mild reaction conditions (80 °C and 2–30 bar of syngas for eugenol; 80 °C and 20–50 bar of syngas for estragole and trans-anethole). The catalytic activity order of the complexes was Rh (PPh₃) > Rh(triphos) > Rh(dppe), while the substrate reactivity followed the trend eugenol > estragole >> trans-anethole. Reaction rates were measured across a wide CO and H₂ pressure range, revealing redistribution between the active monocarbonyl species and an off-cycle (acyl)dicarbonyl complex that becomes dominant at elevated p(CO). The kinetic behavior observed for eugenol hydroformylation with Rh(PPh₃) was consistent with the established hydroformylation sequence involving alkene coordination, hydride migration to substrate and the CO-dependent re-coordination steps that determine catalyst speciation; the subsequent transfer of the alkyl group to the carbonyl ligand and hydrogenolysis complete the catalytic cycle; the H₂ addition or the hydride transfer to the alkene was identified as the rate-determining step, depending on whether low or high p(H₂) values were employed. To obtain statistically reliable kinetic parameters- often challenging in hydroformylation because of parameter covariance and restricted identifiability- we complemented conventional nonlinear regression with Bayesian inference based on the Markov Chain Monte Carlo approach. The resulting posterior distributions were well centered, exhibited realistic variance and provided parameter sets that are sufficiently robust to support mechanistic interpretation and subsequent kinetic modeling. Full article

Trioctyl(alkyl)phosphonium chloride ionic liquids ([P_888n][Cl], n = 8, 14, and 16) were synthesized, characterized, and investigated for the extraction of Co, Ni, Mn, Mg, Zn, and Ca from chloride solutions. The three ionic liquids were very effective for the extraction of cobalt (over 95%) from solutions containing 1 g/L of Co(II) and 4 M HCl or NaCl. Equilibrium cobalt extraction was attained in less than 10 min at 25 °C using the most viscous ionic liquid [P₈₈₈₁₆][Cl]. Based on a speciation diagram for cobalt–chloride species and ultraviolet–visible spectrometric analysis of the phases, it was concluded that Co(II) extraction involved the extraction of the neutral species CoCl₂. Only at high chloride concentration, the anionic exchange mechanism involving $\mathrm{C}\mathrm{o}{\mathrm{C}\mathrm{l}}_4^{2-}$ was the most dominant. The stripping of the loaded ionic liquids can be carried out with water, and the stripped ionic liquids can be recycled up to five times maintaining their extraction effectiveness. In all of the conditions tested, the selectivity of [P_888n][Cl] ionic liquids for the extraction of cobalt over nickel was great, with a separation factor over 25,000 for 5M HCl solutions. Furthermore, very good selectivity for Co(II) over Mg(II) and Ca(II) extraction was also obtained. Conversely, Zn(II) can be selectively extracted over Co(II) and Mn(II) using only diluted [P₈₈₈₁₄][Cl]. Full article

Linear α-olefins (LAOs) from CO/H₂ represent an attractive non-petroleum route, yet their selective formation over Fe catalysts is often limited by CO₂ formation via water–gas shift (WGS) reaction and by secondary hydrogenation that consumes terminal olefins. In this work, we demonstrate that these competing pathways can be regulated on carbon-nanotube (CNT) supported Fe catalysts by controlling the CNT interfacial oxygen environment through NO treatment or high-temperature annealing and by adjusting the Mn incorporation protocol between co-impregnation and stepwise addition. Under identical reaction conditions at 280 °C and 3.0 MPa with an H₂-to-CO ratio of 1, high-temperature treated CNTs improve olefin preservation and LAO retention compared with NO-treated CNTs. Mn promotion further shifts selectivity toward α-olefins and lowers CO₂ selectivity. At the same Fe-to-Mn ratio, the Mn introduction sequence produces distinct reducibility and CO-binding behaviors that lead to different steady-state oxide and carbide phases. XPS, H₂-TPR, and CO-TPD collectively suggest that CNT pretreatment and the Mn protocol modulate near-surface oxygen speciation, reduction kinetics, and CO adsorption strength. Mössbauer spectroscopy confirms a predominantly χ-Fe₅C₂ population and indicates the presence of ε-Fe₂C in selected samples together with residual oxide and superparamagnetic Fe species. These results highlight the importance of controlling the CNT–metal interface and Mn–Fe proximity to enhance LAO retention under high-temperature CO hydrogenation. Full article

A comparative cross-sectional study was undertaken in organized and unorganized dairy sectors to evaluate the prevalence of bovine mastitis and the antibiotic resistance in Staphylococcus spp. of dairy animals and their associated personnel. A total of 391 households (HH) consisting of 211 and 180 HHs from organized and unorganized sectors, respectively, were selected based on 30-cluster sampling methodology in southern and northeastern regions of India. From 391 HHs, a total of 1920 milking cows (organized dairy—533; unorganized dairy—1387) were screened for subclinical and clinical mastitis by the California Mastitis Test (CMT). Out of 1920 milk samples, 1002 milk samples, 362 associated personnel hand and nasal swabs, and 27 milking machine swabs were sourced. The samples were subjected to Staphylococcus spp. by isolation and identification by multiplex polymerase chain reactions (mPCRs) and antibiotic sensitivity testing (ABST) to determine antimicrobial resistance (AMR) profiles. CMT results showed high mastitis prevalence (54.65%) in unorganized farms compared to organized ones (45.78%), with a significant association of mastitis to dairy sectors (p = 0.0004). On speciation, S. aureus isolates were comparatively less than those of coagulase-negative staphylococci (CoNS) (3.5% and 7.7%, respectively) in the organized dairy sector, and the same was recorded for the unorganized dairy sector (0.85% and 13.19%, respectively). In both the dairy sectors, the highest antibiotic resistance for Staphylococcus spp. was observed against the β-lactams (penicillins and cephalosporins) group (71.36% and 76.59%) and the lowest for nitrofurans (3.5% and 3%), oxazolidines (0.7% and 5.1%), and rifamycin (0.7% and 5.1%), respectively. In both the sectors, human isolates had comparatively high mecA positives (15.70% and 15.96%) compared to the animal isolates (8.36% and 12.94%). Based on mPCR, a smaller number of methicillin-resistant S. aureus (MRSA) isolates (3.95%) than methicillin-resistant coagulase-negative Staphylococci (MRCoNS) was detected in milk samples (6.05%), and the same was observed for associated personnel samples (MRCoNS (14.63%) compared to MRSA (1.05%)). In four HHs, mecA positives were detected in both animal and human samples, and this highlights the transmission dynamics of mecA between animals and humans in households. The resistance of Staphylococcus spp. to β-lactams highlights the need for cautious antibiotic use to prevent AMR. Full article

Several lineages within the Eriophyoidea, an ancient group of phytoparasitic acariform mites, produce large protective silk webs on plant surfaces. This study examined the diversity and phylogeny of web-spinning eriophyoids associated with the leaves of Mangifera indica (mango) in Asia, Africa, and North America and Lepisanthes rubiginosa (mertajam) in Vietnam. We report, for the first time, silk-producing structures in Aceria aegyptindicae and Aculops knorri, as well as the presence of tibial seta l’ I and a lobular unpaired prosomal gland in Cisaberoptus kenyae. Molecular and morphological data indicate female dimorphism in A. knorri and reveal cryptic diversity within Cisaberoptus and mango-associated Aceria. The web-spinning species C. kenyae and Ac. aegyptindicae form a strongly supported clade and frequently coexist in syntopy on mango leaves, likely co-producing silk web. Phylogenetic analyses of COI and 28S genes place this clade as sister to Cecidophyinae, while grouping Aberoptus and A. knorri with Anthocoptini and Aceriini. These results demonstrate convergence, cryptic speciation, and unexpected mutualism in web-spinning eriophyoids, providing a framework for future research on the evolution of silk producing organs in this economically important mite group. Full article

Phosphogypsum (PG) and phosphorus tailings (PT) are bulk solid wastes generated by the phosphorus chemical industry whose stockpiling poses significant environmental risks and represents a waste of resources. To achieve the goals of “treating waste with waste” and large-scale disposal, this study proposes a technical pathway involving the co-pyrolysis of phosphogypsum and phosphorus tailings to produce artificial soil-like materials. The effects of raw material ratio, pyrolysis temperature and duration, and biomass addition on the speciation transformation, leaching toxicity, and matrix characteristics of phosphorus (P) and fluorine (F) in the products were systematically investigated. Characterization techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), were employed to elucidate the synergistic immobilization mechanism. The results indicate that under optimized conditions (PG:PT mass ratio of 6:4, pyrolysis temperature of 800 °C, duration of 2–3 h, and biomass addition of 20%–30%), the active forms of harmful elements in the product were significantly reduced. The proportion of water-soluble fluorine decreased from ~39% in raw phosphogypsum to less than 3%, with apatite phosphorus becoming the dominant form of phosphorus. Mechanistic studies reveal that the immobilization process follows a “multi-pathway synergy” mechanism: thermal activation promotes the in situ formation of thermodynamically stable fluorapatite through the reaction of Ca²⁺, PO₄³⁻, and F⁻ (chemical fixation); iron/aluminum oxides in phosphorus tailings and the biochar derived from added biomass provide adsorption sites for surface complexation (physicochemical fixation); and the melting of silicon–aluminum components forms an amorphous silicate network that physically encapsulates pollutant microcrystals. This study provides crucial theoretical foundations and process parameters for the synergistic disposal and soil-like resource utilization of phosphogypsum and phosphorus tailings, demonstrating significant environmental and economic benefits. Full article

This study investigated the remediation effects of iron-modified biochar (FeBC-1 and FeBC-2) on arsenic (As) and cadmium (Cd) co-contaminated paddy soil and elucidated the underlying mechanisms from the perspectives of rhizosphere microbial ecology and plant As and Cd accumulation. A pot experiment with rice was conducted, comprising a control (CK) and iron-modified biochar treatments (FeBC-1 and FeBC-2). Parameters such as As and Cd speciation in rhizosphere soil, bacterial community composition, and the abundance of As-related functional genes were analyzed. The results demonstrated that iron-modified biochar reduced As and Cd accumulation in rice grains by promoting the formation of iron plaques on root surfaces. Meanwhile, the iron-modified biochar significantly enhanced the alpha diversity of bacterial communities and altered their composition. Quantitative analysis of functional genes revealed that the abundance of the As oxidase gene (aioA) increased from 3.54 × 10⁵ in the CK treatment to 7.20 × 10⁵ in FeBC-1 and 7.14 × 10⁵ in FeBC-2, and the abundance of the As efflux gene (arsA) decreased in the biochar-treated groups. These results indicate reduced As bioavailability in the rhizosphere and enhanced transformation of As(III) to As(V). Full article

This study investigates the effects of polypropylene microplastics (PP-MPs) and copper (Cu), applied individually and in combination, on the growth (root and shoot length, fresh and dry biomass), peroxidase (POD) activity, and Cu accumulation of rice seedlings. A hydroponic experiment was conducted with four treatments: control (CK), PP, Cu, and PP+Cu. Exposure to PP-MPs slightly promoted seedling growth, whereas Cu markedly inhibited growth and induced chlorosis. Compared with Cu alone, co-exposure to PP-MPs and Cu (PP+Cu) partially improved shoot growth and alleviated Cu-induced suppression of shoot POD activity. In contrast, root POD activity showed the strongest reduction under PP+Cu (91.7% decrease), revealing a pronounced root–shoot divergence in antioxidant responses. Moreover, total Cu accumulation in seedlings increased by 12.3% in PP+Cu relative to Cu alone, implying that PP-MPs may influence Cu bioavailability and/or internal partitioning. However, Cu speciation and subcellular distribution were not quantified in this study and should be examined in future work. Overall, PP-MPs may simultaneously enhance Cu uptake while partially mitigating shoot-level toxicity, underscoring the complexity of microplastic–metal co-contamination in rice seedling systems. Full article