Search Results (2,089)

This paper demonstrates the successful synthesis of novel hybrid heterogeneous catalysts for the sustainable conversion of CO₂ into cyclic organic carbonates (COCs). The nanocat-alysts have been fabricated by encapsulating pre-formed ultra-small gold nanostructures into a nascent zinc-coordination polymer (ZnCP) framework formed from two organic building blocks, 2,4-naphthalenedicarboxylic acid (1,4-NDC) and 5-amino-1H-tetrazole (5-Atz), which serves as a nitrogen-rich ligand. Applying the fabricated catalysts in the synthesis of COCs yields high yields (up to 97%) and high selectivity (up to 100%), with exceptionally high turnover frequencies (TOFs) (up to 408 h⁻¹). The catalytic process can be carried out under mild conditions (80 °C, 1.5 MPa CO₂) and without the use of solvents. Nitrogen-rich ligand molecules in the structure of ZnCPs enhance catalytic performance thanks to additional nucleophilic centres, which are effective in the epoxides’ ring-opening process. The hybrid catalysts with encapsulated gold nanostructures, which modify the liquid–gas interface between epoxide and CO₂, give significantly higher yields and TOFs for less active epoxides. The designed hybrid nanocatalysts exhibit superior stability under the studied reaction conditions and can be reused without loss of activity. The developed coordination polymers are constructed from green components, and green chemistry principles are applied to prepare these catalytic materials. Full article

Straw returning is a common agricultural practice that can enhance rice (Oryza sativa L.) yield in paddy systems. However, it also leads to a significant increase in greenhouse gas emissions (GHG). Fortunately, this negative impact can be mitigated by implementing enhanced oxygenation strategies during rice cultivation. This study explored the effects of various oxygenation measures on GHG under straw-returning conditions through controlled pot experiments. Six distinct treatments were applied. These included straw not returned (NR, no straw applied), straw returned (SR), controlled irrigation (CI), oxygenation irrigation (OI), application of oxygenated fertilizer (OF, CaO₂), and use of biochar-based fertilizer (CF). All treatment groups, with the exception of the NR group, involved the return of straw to the field. Creating rice production methods that increase yield and decrease emissions is of great importance to agricultural ecology. We postulated that using aeration methods under straw return conditions would stabilize rice yield and reduce GHG. The experimental results were consistent with our hypothesis. The experiment evaluated multiple parameters, including rice yield, leaf photosynthetic performance, soil ammonium and nitrate nitrogen (N) levels, and greenhouse gas emissions. The findings revealed that different oxygenation approaches significantly promoted rice tillering. Oxygenation measures have been shown to enhance rice yield by 19% to 65%. The highest tiller numbers were observed in the SR (22.75) and CF (21.6) treatments. Among all treatments, the CF achieved the highest seed setting rate at 0.94, which was notably greater than that of the other treatments. Total plant biomass was also significantly higher in the straw returning treatment (109.36 g), surpassing all other treatments. In terms of soil nitrogen dynamics, the OF treatment resulted in the highest nitrate nitrogen content. Meanwhile, the ammonium nitrogen concentrations across the four oxygenation treatments (CI, OI, OF, CF) ranged from approximately 7 to 8.9 mg kg⁻¹. Regarding GHG, the CF treatment exhibited the lowest methane emissions, which were 33% lower compared to the straw returning treatment. The OF led to a 22% reduction in carbon dioxide emissions (CO₂) relative to straw returning. Most notably, the CF reduced nitrous oxide emissions by 37% compared to the straw returning treatment. Overall, SR was found to substantially increase GHG. In contrast, all tested oxygenation measures—CI, OI, OF, and CF—were effective in suppressing GHG to varying degrees. Among these, the CF and OF demonstrated the most balanced and outstanding effects, both in reducing emissions and maintaining stable rice yields. Full article

This study investigates the potential use of black coal mining waste as a feedstock for plasma gasification. A national database of coal waste heaps was developed based on standardized criteria such as heap volume (>100,000 m³), accessibility, and environmental risk. From six initially sampled sites, two active and unreclaimed heaps—Jan Karel (Karviná) and Paskov D (Ostrava)—were selected for detailed material analysis due to their favorable characteristics. Subsequent plasma gasification experiments were conducted using sorted coal waste fractions at a temperature of 1600 °C in a pilot-scale plasma reactor. Four trials were performed with fuel flow rates of 15 and 20 kg/h and varying steam/fuel ratios (0.6, 1.0, and 1.3). The results revealed a high syngas yield of up to 92% by volume. Increasing the steam/fuel ratio led to higher hydrogen and carbon dioxide content in the syngas, while lower ratios favored carbon monoxide and trace methane formation. Volt-ampere characteristics of the plasma torch showed that higher nitrogen flow rates required higher voltage to maintain a stable arc. The findings confirm the technical feasibility and efficiency of converting selected coal mining waste into valuable syngas, supporting its future use in advanced waste-to-energy technologies. Full article

Air pollution constitutes a major environmental determinant of cardiovascular morbidity and mortality worldwide. Western Macedonia, Greece, has historically hosted the largest lignite mining and combustion complex in Southeastern Europe, creating a unique exposure environment. This study investigates the relationship between air pollutant concentrations and cardiovascular hospital admissions over a ten-year period in this lignite-dependent region. Daily concentrations of particulate matter (PM₁₀), sulfur dioxide (SO₂), nitric oxide (NO), nitrogen dioxide (NO₂), and total nitrogen oxides (NO_x) were collected from regional monitoring stations for the winters of 2011–2021, while corresponding daily cardiovascular hospital admissions were obtained from the regional hospitals of Kozani, Ptolemaida, Florina, and Grevena. Spearman’s rank correlations and Friedman’s non-parametric tests were applied to assess temporal and spatial associations between pollutant levels and hospital admissions. A marked decline in air pollutant concentrations, particularly PM₁₀ and SO₂, was observed across the decade, coinciding with a significant reduction in cardiovascular hospitalizations. Specifically, PM₁₀ levels fell from ~75 μg/m³ to ~30 μg/m³ in Florina and from ~53 μg/m³ to ~11 μg/m³ in Ptolemaida, while SO₂ concentrations decreased by more than 90% across all sites. Cardiovascular admissions declined by 20–40% depending on the region over the same period. Significant but modest positive correlations were detected between PM₁₀ and admissions in Florina (ρ = 0.138, p = 0.017), SO₂ in Ptolemaida (ρ = 0.122, p = 0.034), and NO₂ in Kozani (ρ = 0.115, p = 0.045). Regions located near lignite combustion sites consistently exhibited higher pollutant levels and hospitalization rates. The study provides quantitative evidence linking air pollution from lignite combustion to adverse cardiovascular outcomes. The parallel decline in both pollution levels and hospital admissions underscores the cardiovascular benefits of emission reduction and the ongoing energy transition in Western Macedonia. Continuous air quality monitoring and preventive public health measures remain essential for safeguarding cardiovascular health in former coal-based regions. Full article

Open-pit coal mining is characterized by multiple pollution sources, diverse types, and extensive affected areas, leading to complex air pollution with wide diffusion. Traditional fixed monitoring methods cannot address these limitations. Taking a coal mine in Xinjiang as a case study, this study developed a drone-mounted mobile atmospheric monitoring system, focusing on nitrogen dioxide (NO₂) and suspended particulate matter (PM_2.5 and PM₁₀) to explore their distribution, diffusion patterns, and influencing factors. The results show distinct seasonal pollutant characteristics: NO₂ and ozone (O₃) dominate in summer, while particulate matter prevails in winter. The temporal distribution exhibits a bimodal pattern, with high levels in the early morning and evening hours. Spatially, higher pollutant concentrations accumulate vertically below ground level, while lower levels are observed above it. Horizontally, elevated concentrations are found along northern transport corridors; however, these levels become more uniform at greater heights. A spatiotemporal prediction model integrating convolutional neural network (CNN) and long short-term memory (LSTM) network was successfully applied to real-time pollutant prediction in open-pit coal mining areas. This study provides a reliable mobile monitoring solution for open-pit coal mine air pollution and offers valuable insights for targeted pollution control in similar mining areas. Full article

The environmental impact of trade liberalization hinges on a central tension between its ‘scale effect’ and its ‘technique and composition effects’. This study uses the Regional Comprehensive Economic Partnership’s (RCEP) influence on China-ASEAN green agricultural trade as a quasi-natural experiment to test the net outcome of this conflict. Leveraging panel data from 2003–2023 and a combined Difference-in-Differences (DID) and Instrumental Variables (IV) methodology, we find that while RCEP-driven agricultural expansion (the scale effect) did significantly increase NO₂ emissions by 21.80 units (p = 0.011), the total effect of RCEP was counter-intuitively and significantly negative. The agreement produced a context-specific environmental co-benefit, achieving a net reduction of 99.45 $\mathsf{\mu }\mathrm{m}\mathrm{o}\mathrm{l}/{\mathrm{m}}^2$ of NO₂ (p = 0.008). The agreement produced a specific reduction in combustion-related air pollution, achieving a net reduction of 99.45 $\mathsf{\mu }\mathrm{m}\mathrm{o}\mathrm{l}/{\mathrm{m}}^2$ of NO₂ (p = 0.008). We caution that this outcome is contextual: it is driven not only by a still-weak green technology effect (a 0.55 unit reduction, p = 0.095) but more critically by a structural shift in trade towards lower-emission fruit and vegetable products (coefficient = −0.13, p = 0.077), suggesting that environmental gains are currently contingent on product composition rather than broad decarbonization. This reveals that environmental pressures from scale are, for now, being offset by structural optimization, highlighting the urgent need for refined emission monitoring and targeted green policies within RCEP to solidify these environmental gains. Full article

Polymeric materials have become important components in prefilled syringes, drug delivery systems, and advanced medical devices. Background/Objectives: Nitrogen dioxide gas is used for the terminal sterilization of drug delivery systems. For the implementation of sterilization methods, compatibility with materials must be demonstrated such that the materials maintain product requirements and specifications after sterilization and at the time of use (i.e., product shelf life). Methods: Commonly used polymers were selected based on their chemical structures to provide insight into the nature of reactions that occur at the temperature and NO₂ concentration levels used in the sterilization process. After exposure to the NO₂ process, materials were evaluated for chemical, mechanical, and biocompatibility properties. Results: In this paper, we demonstrated the compatibility of polymers comprising carbonyl, unsaturated ester, and ketone groups which have been used in medical devices sterilized with NO₂. No significant chemical or physical changes were observed upon the treatment of Amorphous Polyester, Polysulfone (PSU), Polycarbonate (PC), PolyEtherEtherKetone (PEEK), PolyArylEtherKetone (PAEK), and Polypropylene (PP) with NO₂ at a sterilization temperature of 20 °C. At this relatively low sterilization temperature, the reactions of NO₂ with the polymer do not typically occur because the activation energies of these reactions require much higher temperatures. Conclusions: Not all materials will be compatible with NO₂ sterilization, and even with the established data, many devices will need to have their polymers evaluated for compatibility before moving to NO₂ sterilization. These results will provide guidance to device designers selecting materials for new drug delivery devices and to regulators that review the safety and efficacy of these devices. Full article

This study is based on data obtained as part of continuous monitoring of small gas impurities (SO₂, NO₂, NO), mass concentration of aerosol particles PM_2.5 and meteorological parameters, which was first implemented at the Tankhoi observation point (southeastern coast of Lake Baikal, Russia) from October 2023 to May 2025. Statistical methods and the non-parametric wind regression receptor model (NWR) were used to analyze temporal variability and identify sources of pollution. It was found that the concentrations of gas impurities have a clearly pronounced winter maximum: the median values for sulfur dioxide and nitrogen in winter reached 9.2 μg/m³ and 13.8 μg/m³, respectively, which is associated with emissions from coal-fired thermal power plants and unfavorable meteorological conditions (inversions, low boundary layer height). In contrast to gases, PM_2.5 demonstrated a summer peak up to 43.5 μg/m³ in July–August 2024 due to abnormally hot weather and forest fires. The daily course of sulfur dioxide was characterized by an atypical daily maximum caused by the convective transport of polluted air masses from the upper layers of the boundary layer. During this period, higher concentrations of sulfur dioxide caused by long-range high-altitude transport of emissions from regional thermal power plants can reach the ground surface, leading to an increase in their concentration in the near-surface layer. Using the NWR model, the influence of regional thermal power plants located 100–150 km northwest of the station on the levels of SO₂ and NO₂ was confirmed. The results also highlight the contribution of local sources, such as vehicles, stoves, and shipping, to the formation of NO and PM_2.5. Full article

Underground mining environments present elevated occupational health risks, primarily due to substantial exposure to diesel exhaust emissions within confined and poorly ventilated spaces. This study assesses the real-world performance of two advanced retrofit emission control systems—Proventia NOxBuster and Purifilter—installed on underground mining trucks operating in a Spanish mine. Emissions of carbon monoxide (CO), nitric oxide (NO), and nitrogen dioxide (NO₂) were quantified using a Testo 350 multigas analyser, while ultrafine particle (UFP) concentrations were measured with an Engine Exhaust Particle Sizer (EEPS-3090) equipped with a thermodiluter. Controlled tests under both idling and acceleration conditions revealed substantial reductions in pollutant emissions: CO decreased by 60–98%, NO by 51–92%, and NO₂ by 20–87%, depending on the system and operational phase. UFP concentrations during idling dropped by approximately 90%, from 542,000 particles/cm³ in untreated trucks to below 50,000 particles/cm³ in retrofitted vehicles. Under acceleration, the Proventia NOxBuster achieved reductions exceeding 95%. Conversely, Purifilter-equipped trucks exhibited a counterintuitive increase in UFPs within the 5.6–40 nm range, potentially due to ammonia slip events during selective catalytic reduction (SCR). Despite these discrepancies, both systems demonstrated considerable mitigation potential, albeit highly dependent on exhaust temperature (optimal: 200–450 °C), urea dosing precision, and maintenance protocols. This work underscores the necessity of in situ performance verification, regulatory vigilance, and targeted intervention strategies to protect underground workers effectively. Further investigation is warranted into the long-term health benefits, system durability, and nanoparticle emission dynamics under variable load conditions. Full article

Background: Given the rapid global increase in asthma cases, understanding the impact of climate change on respiratory health is necessary for evidence-based policymaking, particularly in low- and middle-income countries (LMICs). Objectives: To estimate the short-term associations between temperature (mean and diurnal range), particulate matter (PM_2.5 and PM₁₀), nitrogen dioxide (NO₂), ozone (O₃), and childhood asthma exacerbations in Cape Town, South Africa. Methods: We analysed daily hospital records (n = 7753; 2009, 2014, 2019) alongside citywide air quality and meteorological data using negative binomial mixed-effects models and distributed lag non-linear models to capture delayed effects. Results: NO₂ and PM₁₀ were consistently associated with a higher exacerbation risk, with additional delayed effects observed for PM_2.5, PM₁₀, and NO₂. Mean temperature and diurnal temperature range were also linked to an increased risk at short (lag 0–1) and medium (lag 4–5) delays. Conclusions: Temperature variability and traffic-related air pollution contribute to childhood asthma exacerbations in urban LMIC settings. The findings support child-centred early warning systems and stricter air quality controls aligned with WHO guidance. Full article

Simultaneous catalytic elimination of nitrogen oxides (NO_x) and volatile organic compounds (VOCs) represents a promising technology for addressing the synergistic pollution of fine particulate matters of <2.5 μm diameter (PM_2.5) and O₃. Nevertheless, it has been maintaining significant challenges in practical implementation, particularly the inherent mismatch in temperature windows between NO_x reduction and VOCs oxidation pathways, coupled with catalyst poisoning and deactivation phenomena. These limitations have hindered the industrial application of bifunctional catalysts for the removal of concurrent pollutant. This review systematically explored the fundamental mechanisms and functional roles of active sites in controlling synchronous catalytic processes. The mechanism of catalyst deactivation caused by multiple toxic substances has been comprehensively analyzed, including sulfur dioxide (SO₂), water vapor (H₂O), chlorine-containing species (Cl*), reaction by-products, and heavy metal contaminants. Furthermore, we critically evaluated the strategies of doping regulation, nanostructure engineering and morphology optimization to enhance the performance and toxicity resistance of catalysts. Meanwhile, emerging regeneration techniques and reactor design optimizations are discussed as potential solutions to improve the durability of catalysts. Based on the above critical aspects, this review aims to provide insights and guidelines for developing robust catalytic systems capable of controlling multi-pollutants in practical applications, and to offer theoretical guidance and technical solutions to bridge the gap between laboratory research and industrial environmental governance applications. Full article

Total ammonia nitrogen (TAN) is a common and potent neurotoxic pollutant in aquatic environments. Due to their strong adsorption capacity, titanium dioxide nanoparticles (n-TiO₂), a widely used engineered material, can induce combined toxicity with multiple pollutants. However, the combined neurotoxicity of n-TiO₂ and TAN and its underlying mechanisms remain unclear. In this study, zebrafish embryos were exposed to TAN (0, 0.1, 1, 10 mg/L) and n-TiO₂ (100 µg/L) individually or in combination for 120 h. The results indicated that co-exposure to n-TiO₂ and TAN significantly increased the bioaccumulation of TAN in zebrafish embryos compared to TAN alone. Consequently, this led to exacerbated neurotoxicity, manifested as developmental impairments and abnormal motor behavior. Mechanistic investigations revealed that the co-exposure aggravated developmental neurotoxicity by triggering neuronal apoptosis and oxidative stress, disrupting the cholinergic and dopaminergic systems, and impairing neural and retinal development. Transcriptomic analysis further indicated that the co-exposure predominantly perturbed neurodevelopment, oxidative stress, and apoptosis. In conclusion, this study confirms that n-TiO₂ significantly amplifies TAN-induced neurodevelopmental toxicity by promoting its bioaccumulation and synergistically disrupting multiple neurophysiological processes. These findings provide crucial scientific evidence for assessing the combined ecological risks of nanomaterials and conventional pollutants. Full article

Nitrogen dioxide (NO₂) and particulate matter of 2.5 microns (PM_2.5) impact health outcomes. This study utilized a pre- to post-test study design to evaluate the impact of air purifiers fitted with a high-efficiency particulate air (HEPA) and carbon filters in reducing indoor NO₂ and PM_2.5. Sixty-seven low-income homes in Lowell, Massachusetts, were included in this study. Home visits were conducted every four months for 12 months. At each visit, we conducted environmental sampling, measuring indoor NO₂, PM_2.5, stove use, temperature, and humidity over 5–7 days. We collected environmental exposure data using questionnaires. Air purifiers were introduced after the 4th month. Linear mixed models were used to predict changes in NO₂ and PM_2.5, with independent predictors as fixed effects and homes as random effects. The geometric mean (GM) for NO₂ decreased by 36% from 20.16 to 12.79 ppb (p < 0.001). GM for PM_2.5 decreased by 45% from 17.12 to 9.16 µg/m³ (p < 0.001). We found that an increase in air purifier use resulted in a significant decrease in NO₂ and PM_2.5, and an increase in stove usage increased NO₂. HEPA/carbon filters have the potential to improve indoor air quality by reducing NO₂ and PM_2.5, enabling the tailoring of interventions to mitigate these air pollutants. Full article

As global warming accelerates, the Paris Agreement has emphasized the urgent need for technologies that reduce and manage carbon dioxide emissions. Consequently, carbon capture and storage (CCS) has emerged as a critical area of research. For the safe and efficient transportation of captured carbon dioxide in cryogenic tanks, the design must accurately account for the phase change behavior of liquefied carbon dioxide (LCO₂). This study proposes a numerical approach to evaluate the thermal insulation performance of cryogenic tanks by simulating the phase change process of LCO₂. The phase transition of LCO₂ was simulated in a horizontally oriented Type-C cryogenic tank using the open-source computational fluid dynamics (CFD) framework OpenFOAM (v2312). To validate the numerical methodology, the phase change in liquefied nitrogen (LN₂) inside a tank was first simulated and compared with available experimental data. A mesh-independence study was then conducted to determine the optimal grid resolution, and the effects of different equations of state (EOS) for both liquid and gaseous phases, as well as various turbulence models, were examined. The boil-off rate (BOR) and boil-off gas (BOG) generation within the tank were predicted, and variations in internal pressure and flow fields were analyzed. The simulation results over 5000 s showed that the internal tank pressure increased from 7.8 bar to 8.1 bar, and the average temperature rose by approximately 1.3 K. The total mass of LCO₂ decreased from 1439.3 kg to 1431.0 kg. Full article

Against the backdrop of global climate change, alterations in precipitation regimes—including the increasing frequency of extreme events—have become more widespread, exerting profound impacts on terrestrial ecosystems and reshaping greenhouse gas (GHG) emission dynamics in wetlands. Wetlands, as unique ecosystems formed at the interface of terrestrial and aquatic environments, play a critical role in regulating carbon source–sink functions. In this study, we conducted in situ field simulation experiments to examine how precipitation changes influence the seasonal fluxes of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) in the Wayan Mountain headwater wetlands, and further explored the regulatory effects of vegetation attributes and soil physicochemical properties on these fluxes. The results revealed that a moderate increase in precipitation (+25%) enhanced CO₂ emissions and vegetation growth while suppressing CH₄ and N₂O fluxes, indicating a positive ecosystem response to additional water supply. In contrast, extreme precipitation changes (+75% and −75%) weakened the coupling between GHG fluxes and soil factors, resulting in reduced CO₂ flux, amplified variability in CH₄ and N₂O emissions, and inhibited vegetation growth and community diversity. The dominant controls differed among gases: CO₂ was primarily regulated by soil carbon pools, CH₄ was highly sensitive to water availability, and N₂O was influenced by soil nitrogen, pH, and salinity. Overall, moderate increases in precipitation enhance the carbon sink capacity and community stability of alpine wetlands, whereas extreme hydrological fluctuations undermine ecosystem functioning. These findings provide important insights into carbon cycling processes and regulatory mechanisms of alpine wetlands under future climate change scenarios. Full article