Search Results (8,037)

VOCs are significant precursors for the formation of O₃ and SOA, directly impacting human health. This study employs multiple approaches to analyzing atmospheric VOCs by focusing on OVOCs including aldehydes, ketones, and phenols, with a case study in Beijing, China. We analyzed the concentration levels and compositions of VOCs and their atmospheric activities, offering a new perspective on VOCs. This analysis was conducted through offline measurements of volatile phenols and carbonyl compounds, complemented by online VOC observations during the summer period of high O₃ levels. The total atmospheric VOCs concentration was found to be 51.29 ± 10.01 ppbv, with phenols contributing the most (38.87 ± 11.57%), followed by carbonyls (34.91 ± 6.85%), and aromatics (2.70 ± 1.03%, each compound is assigned to only one category based on its primary functional group, with no double counting). Carbonyls were the largest contributors to the OFP at 59.03 ± 14.69%, followed by phenols (19.94 ± 4.27%). The contribution of phenols to the SOAFP (43.37 ± 9.53%) and the L_OH (67.74 ± 16.72%) is dominant. Among all quantified VOC species, phenol and formaldehyde exhibited the highest species-level contributions to atmospheric reactivity metrics, including L_OH, OFP and SOAFP, owing to their combination of elevated concentrations and large kinetic or MIR coefficients. Using the PMF model for source analysis, six main sources of volatile organic compounds were identified. Solvent use and organic chemicals production were found to be the primary contributors, accounting for 31.76% of the total VOCs emissions, followed by diesel vehicle exhaust (17.80%) and biogenic sources (15.51%). This study introduces important OVOCs such as phenols, re-evaluates the importance of OVOCs and their role in atmospheric chemical processes, and provides new insights into atmospheric VOCs. These findings are crucial for developing effective air pollution control strategies and improving air quality. This study emphasizes the importance of OVOCs, especially aldehydes and phenols, in the mechanism of summer O₃ generation. Full article

Accurate quantification of aircraft emissions and their uncertainties is essential for well-informed policy-making, air quality management, and the development of sustainable airport strategies. This study addresses uncertainties in aircraft emission estimates implemented for local air pollutants with hourly resolution at six European airports. Publicly available flight-tracking data were used to determine aircraft movements and types, but they typically lack detailed information on aircraft engine models, thus contributing to uncertainties in emission factors. Times-in-mode for take-off, climb-out, and approach modes followed International Civil Aviation Organization (ICAO) recommendations, while taxi times, known to vary between airports, were modeled using statistical distributions derived from Eurocontrol, and the contribution of taxi time to overall uncertainty in emission estimates was investigated. Monte Carlo simulation combined with Sobol sensitivity analysis identified the relative contribution of each uncertainty source. On average, the results indicate an uncertainty of 23% for CO, 34% for HC, 7% for NO_x, and 21% for PM across the airports analyzed. Overall, the proposed methodology introduces a novel framework utilizing publicly available, hourly resolved flight-tracking data with robust uncertainty analysis to estimate airport-level emissions with enhanced reliability, providing crucial information for local air quality assessment and policy development. Full article

Green hydrogen has become a fundamental pillar in the transition towards a low-carbon economy, due to its ability to produce energy without polluting emissions and from renewable sources such as solar and wind. Unlike other hydrogen production technologies, green hydrogen is obtained through water electrolysis using renewable electricity, which makes it a clean and sustainable fuel, ideal for hard-to-decarbonized sectors such as heavy industry and long-distance transportation. The main objective of this review is to analyze the evolution, trends, and knowledge gaps related to the sustainability of green hydrogen, identifying the main research focus areas, scientific actors, and emerging opportunities. To do this, 1935 scientific articles indexed in Scopus and WOS were examined under PRISMA 2020. Among the most relevant results, an exponential growth in scientific production on hydrogen and sustainability is observed, with Asian authors leading due to strong national commitments. The main challenges identified by the scientific community are related to efficiency, profitability, optimization, integration into sustainable energy systems, and emission reduction. Green hydrogen technologies are central to future energy, and success depends on international collaboration, innovation, and stable policies that support large-scale, sustainable clean energy adoption. Full article

In the pursuit of high-quality economic development, addressing the challenge of high pollution and carbon emissions has become a critical issue. The rapid advancement of digital technology offers novel opportunities and tools to effectively mitigate these challenges. This study examines how digital technology empowerment can enhance the effectiveness of low-carbon city pilot (LCCP) policies in mitigating high pollution and carbon emissions, thereby improving green economic efficiency (GEE), using data from 283 Chinese cities between 2006 and 2021. The method adopted is a DID framework tailored for settings with staggered treatment adoption. Our analysis focuses on the low-carbon city pilot initiative, examining its consequences and how it interacts with digital technology. The results indicate that (1) the LCCP policy significantly promotes green economic efficiency; (2) digital technology empowerment demonstrates a substantial positive moderating impact upon the policy outcome, thus considerably reinforcing low-emission pilot policies’ improvement effect on GEE; (3) there are regional variations in the policy effectiveness, with the eastern region showing the most pronounced improvement, followed by the central region, while the western region exhibits a relatively lower response. This study provides theoretical and empirical support for further integrating digital technology with low-carbon policies and advancing urban green and high-quality development. Full article

In the context of promoting strategies to mitigate the global warming effect resulting from greenhouse gas emissions produced by human activities, ammonia stands out as an important player in the decarbonization of various sectors, including transportation, energy, and other industries. Ammonia is an effective carrier of hydrogen, having three times the volumetric energy density of hydrogen itself. In this study, the authors present findings obtained from a group of experiments and simulations conducted on a diesel engine operating at a constant speed and under different loads, using a dual-fuel method in which ammonia was injected into the intake manifold to partially replace the original diesel fuel. The results demonstrate that it is possible to reduce fuel consumption and CO₂ emissions. NO_x dropped by 40.8% and soot by 13.4% under heavy load, while under light load, they dropped by 50.5% and 23.3%, respectively. Full article

Background: Healthcare is a large contributor to greenhouse gas (GHG) emissions, contributing to climate change and health impairments. However, the magnitude of health and climate benefits of local and regional GHG mitigation strategies has not been well quantified. Few studies have demonstrated the use of public tools for this purpose in healthcare facilities. Methods: We evaluated several renewable energy and energy efficiency scenarios focused on one academic medical center in New York State. We used the Environmental Protection Agency’s (EPA) publicly available AVoided Emissions and geneRation Tool to estimate avoided GHG and health-harmful air pollutant emissions. The economic value of the resulting avoided health and climate damages was quantified using EPA’s CO-Benefits Risk Assessment screening tool. Results: Transitioning one healthcare institution to 100% solar energy and improving energy efficiency by 25% could yield approximately $807,000 to $1.5 million in annual health savings, with an additional $2.3 million benefits in avoided climate damages. There is an approximate $108.5–$196.6 million in annual climate and health benefits when extrapolating these energy solutions to hospitals across the same state. Conclusions: There are significant health savings from healthcare GHG mitigation strategies. This application of publicly available and accessible tools demonstrates ways to integrate climate and health benefits into local decision-making around climate change mitigation and sustainability efforts. Full article

Vehicle emissions are key precursors to near-ground ozone and secondary aerosol formation. While China’s clean air actions have significantly reduced particulate pollution, ozone levels continue to rise in some city clusters, calling for a deeper understanding of volatile organic compound (VOC) emissions from gasoline vehicles. This study systematically evaluated the impacts of fuel composition (China 6b vs. Methyl tert-butyl ether -free (MTBE-free) gasoline), engine type (Port fuel injection (PFI) vs. Gasoline direct injection (GDI)), and ambient temperature (25 °C vs. −7 °C) on VOC emissions and ozone formation potential (OFP) under the World Harmonized Light-Duty Test Cycle (WLTC). Results of dynamometer experiments showed that MTBE-free gasoline reduced total VOC emissions by 47% compared to China 6b fuel, with aromatics accounting for 69% of this reduction. PFI vehicles exhibited higher VOC emissions than GDI vehicles at 25 °C, though this difference diminished at −7 °C. Low temperatures significantly increased VOC emissions and OFP, increasing by a factor of 10–13 compared to 25 °C. Aromatics were the dominant OFP contributors under all conditions. Our findings highlight the importance of fuel reformulation and temperature-specific emission controls in mitigating ozone pollution, particularly under cold-start conditions. Full article

This paper presents a numerical study on the deployment of Overfire Air (OFA) technology in coal-fired thermal power plants in Kazakhstan to reduce harmful emissions. The simulation utilized a digital model of the combustion chamber of the BKZ-75 boiler at Shakhtinsk thermal power plant, which utilizes high-ash Karaganda coal containing 35.10% ash. During the development of two-stage combustion technology, different methods of supplying extra air via OFA injectors were examined. Various positions within the combustion chamber were evaluated for their placement: at heights of h = 0.165 m; 0.75 m; 1.375 m; 2.25 m; 2.5 m; 8 m; 9.4 m; 10 m; 11 m; and 12 m. The baseline combustion mode (OFA = 0%) and several additional air injector settings were analyzed, including OFA levels of 5%, 10%, 15%, 18%, 20%, 25%, and 30% of the total air volume. Numerical simulations generated temperature distributions along with carbon monoxide (CO) and nitrogen (NO) concentration fields, both inside and outside the combustion chamber outlet. Research indicates that the most effective reduction in pollutant emissions happens when OFA injectors are positioned at 9.4 m and supply supplementary air at an OFA rate of 18%. Under these settings, the carbon monoxide concentration at the combustion chamber outlet decreases by approximately 36%, while nitrogen oxide levels drop by 25%, compared to the baseline condition (OFA = 0%). These insights can be utilized to upgrade boiler units, promoting cleaner fuel combustion in coal-fired thermal power plants. Full article

Civilisational progress contributes to an increase in the number of vehicles on the road, thereby intensifying air pollutant emissions and accelerating the degradation of the natural environment. Effective protection of urban areas against air pollution enhances safeguarding against numerous allergies and diseases resulting from unplanned and unintended absorption of harmful pollutants into the human body. Sustainable urban planning requires the collaboration of multiple scientific disciplines. In this context, measurement becomes crucial, as it reveals the spatial scale of the problem and identifies existing disparities. This study uses an integrated approach of standard measurement methods and statistical and geostatistical data analysis, identifying PM₁ fractions that are not included in EU air quality monitoring. The hypothesis explores how surface-based results correspond to point-based results from national air quality monitoring. The presented implications demonstrate similarities and differences between the studied measurement methods and the spatial distributions of PM₁₀, PM_2.5, and PM₁ dust. Full article

Accurate estimation of ship emissions is essential for the effective enforcement of emission control policies in inland waterways. However, existing “bottom-up” models face significant challenges owing to severe data scarcity for inland ships, particularly regarding ship static parameters. This study proposes a novel data fusion and machine learning framework to address this issue. The methodology integrates real-time SO₂ and CO₂ pollutant concentrations on the Nanjing Dashengguan Yangtze River Bridge, Automatic Identification System (AIS) data, and meteorological information. To address the scarcity of design data for inland ships, web scraping was used to extract basic parameters, which were then used to train five machine learning models. Among them, the XGBoost model demonstrated superior performance in predicting the main engine rated power. A refined activity-based emission model combines these predicted parameters, ship operational profiles, and specific emission factors to calculate real-time emission source strengths. Furthermore, the model was validated against field measurements by comparing the calculated and measured emission source strengths from ships, demonstrating high predictive accuracy with R² values of 0.980 for SO₂ and 0.977 for CO₂, and MAPE below 13%. This framework provides a reliable and scalable approach for real-time emission monitoring and supports regulatory enforcement in inland waterways. Full article

The energy transition in the transportation sector makes hydrogen a promising candidate as a fuel for internal combustion engines; however, its tendency to knock limits its use to lean mixtures, resulting in a reduction in performance. In this context, water injection represents a technical solution capable of reducing both the risk of knocking and the pollutant emissions of nitrogen oxide (NOx). Although several studies have been published on the benefits of water injection, its capacity to suppress high-intensity knocking phenomena was never investigated and is not traceable in the scientific literature. On account of this lack, the authors of the present paper experimentally evaluate the effectiveness of port water injection in suppressing high-intensity knock phenomena and its potential in terms of nitrogen oxide emission reduction. Differently from previous works, a highly reactive fuel (PRF60) was adopted to reproduce, as closely as possible, the knocking tendency of hydrogen. The tests were carried out on a single-cylinder CFR engine, suitably modified to allow port water injection, operating with stoichiometric air–fuel mixture (λ = 1) and at low engine speed, which constitutes the most critical condition, since it allows for heavy knocking and is less favorable for injected water evaporation. Moreover, aiming to assess the effect of spray atomization, the tests were repeated using three different water injection pressure levels. The study presented, however, is confined to the effects of port water injection on knock suppression and NOx emission reduction, while no engine performance or efficiency variation were considered. The results showed that port water injection, with water addition up to 40% by mass with respect to fuel, enables an almost complete suppression of high-intensity knocking phenomena, along with a significant reduction in NOx emissions (up to −62%). Full article

To address climate change and advance environmental sustainability in the context of the United Nations Sustainable Development Goals (SDGs), particularly SDG 9 (Industry, Innovation and Infrastructure), SDG 11 (Sustainable Cities and Communities), and SDG 13 (Climate Action), China has actively promoted digital trade development under its carbon peaking and carbon neutrality goals. However, whether digital trade contributes to environmental improvement, and through which mechanisms it does this, remains an open empirical question. This study examines whether and how digital trade development affects environmental pollution in China, with particular emphasis on spatial spillover effects and underlying mechanisms. Using provincial panel data from 2009 to 2023, we employ a spatial Durbin model combined with a mediation analysis framework. The results show that digital trade development has increased steadily in China and significantly reduces local environmental pollution, indicating a clear green effect. The spatial Durbin model shows that the environmental benefits of digital trade are unevenly distributed across space, with pollution reductions in core regions accompanied by increased emissions in neighboring areas. Further mechanism analysis indicates that industrial structure upgrading and consumption structure transformation are key channels through which digital trade development improves environmental sustainability. These findings provide important insights for coordinating digital trade expansion with regional environmental governance and low-carbon transition strategies. Full article

Highly accurate quantitative detection of heavy metals is crucial for preventing environmental pollution and safeguarding public health. To address the demand for sensitive and specific detection of Cu²⁺ ions, we have developed carbon dots using a simple hydrothermal process. The synthesized carbon dots are highly stable in aqueous media, environmentally friendly, and exhibit strong blue photoluminescence at 440 nm when excited at 352 nm, with a quantum yield of 5.73%. Additionally, the size distribution of the carbon dots ranges from 2.0 to 20 nm, and they feature excitation-dependent emission. They retain consistent optical properties across a wide pH range and under high ionic strength. The photoluminescent probes are selectively quenched by Cu²⁺ ions, with no interference observed from other metal cations such as Ag⁺, Ca²⁺, Cr³⁺, Fe²⁺, Fe³⁺, Hg²⁺, K⁺, Mg²⁺, Sn²⁺, Pb²⁺, Sr²⁺, and Zn²⁺. The emission of carbon dots exhibits a strong linear correlation with Cu²⁺ concentration in the range of 0–14 μM via a static quenching mechanism, with a detection limit (LOD) of 4.77 μM in water. The proposed carbon dot sensor is low cost and has been successfully tested for detecting Cu²⁺ ions in general water samples collected from rivers in Taiwan. Full article

Urban rivers are essential resources for human societies; however, their degradation poses serious public health, economic, and environmental risks. Conventional physical remediation methods can partially mitigate pollution by targeting specific contaminants, but they are often limited in scope, lack long-term sustainability, and fail to restore ecological functions. In contrast, biotechnological approaches integrated with ecological engineering offer sustainable and nature-based solutions for river depollution, conservation, and revitalization. Although these strategies are supported by a solid theoretical framework and successful applications in other aquatic systems, their large-scale implementation in urban rivers has only recently begun to gain momentum. This review critically examines strategies for the revitalization of polluted urban rivers, progressing from conventional remediation techniques to advanced biotechnological interventions. It highlights real-world applications, evaluates their advantages and limitations, and discusses policy frameworks and management strategies required to promote the broader adoption of biotechnological solutions for sustainable urban river restoration. The goal is to demonstrate the transformative potential of integrated biotechnological, eco-engineering, and data-driven approaches—particularly microbial, phytoplankton-based, and biofilm systems—to reduce energy demand and carbon emissions in urban river restoration while highlighting the need for scalable designs, adaptive management, and supportive regulatory frameworks to enable their large-scale implementation. Full article

Introduction: Open-circuit cooling systems (OCCSs), integral to many industrial processes, often release blowdown water containing elevated concentrations of treatment chemicals. These discharges, if uncontrolled, pose substantial risks to aquatic ecosystems and human health. This study addresses the environmental implications of chemical emissions from OCCS blowdown through the development of a predictive model designed to estimate contaminant concentrations in receiving water bodies. Methods: The research employs a computational model based on mass-balance equations to simulate the dynamics of chemical emissions from blowdown water. It incorporates key operational variables, including flow rates, degradation rates, and evaporation characteristics. The model evaluates two chemical dosing strategies, continuous and fractional, and their resultant pollutant dispersal patterns in river systems. Validation was performed using empirical data from sulfuric acid (H₂SO₄) applications at a nuclear power plant between 2015 and 2022. Results: The model demonstrated strong agreement with observed sulfate ion concentrations in the receiving water body, confirming its predictive reliability. Continuous dosing resulted in stable levels of pollutants, while fractional dosing caused temporary peaks that did not exceed regulatory limits. Conclusion: The modeling of blowdown water reveals important implications for river water quality and suggests that current wastewater management practices may be insufficient, benefiting from the integration of predictive modeling for blowdown discharges in industrial settings. Full article