Nitrogen Oxides Research Articles

Room Temperature Reduction of Nitrogen Oxide on Iron Metal-Organic Frameworks.

Nitrogen oxides represent one of the main threats for the environment. Despite decades of intensive research efforts, a sustainable solution for NOx removal under environmental conditions is still undefined. Using theoretical modelling, material design, state-of-the-art investigation methods and mimicking enzymes, we have found that selected porous hybrid iron(II/III) based MOF material are able to decompose NOx, at room temperature, in the presence of water and oxygen, into N2 and O2 and without reducing agents. This paves the way to the development of new highly sustainable heterogeneous catalysts to improve air quality. This article is protected by copyright. All rights reserved.

Impact of Thunderstorm Activities on Tropospheric NOx Over Koshi Province of Nepal and Their Possible Role in Climate Change

Lightning, a natural atmospheric phenomenon, plays a significant role in altering atmospheric chemistry and air quality by generating nitrogen oxides (NOX). This research aims to explore the correlation between lightning stroke density and atmospheric NOX over Koshi Province of Nepal by using observational data. Over the course of three year (2018, 2019 and 2020), sessional (lightning pre-dominant; pre-monsoon and post-monsoon) measurements of lightning activity (lightning stroke density) were obtained from Global Lightning Dataset (GLD 360) and NOX data acquired from NASA’s Ozone Monitoring Instrument (OMI). The computation was conducted by using programming language PYTHON. Correlation analysis was performed to examine the relationship between lightning stroke density and NOX concentrations by considering lightning stroke density as independent variable and average NOX as dependent variable. Our analysis shows a notable positive correlation between lightning stroke density and average NOX over Koshi Province of Nepal. The values of correlation coefficient (R) was found 0.625, 0.630 and 0.511 in pre-monsoon of years 2018, 2019 and 20120 respectively and 0.654, 0.605 and 0.370 respectively in post-monsoon. Increased lightning activity corresponded to heightened NOX concentrations, especially during pre-monsoon and post-monsoon. These results indicate that lightning significantly contributes to NOX emissions in Koshi Province. Understanding the relationship between lightning and NOX is essential for study atmospheric chemistry and assessing the impact of lightning on atmosphere.

Reducing Soil-Emitted Nitrous Acid as a Feasible Strategy for Tackling Ozone Pollution.

Severe ozone (O3) pollution has been a major air quality issue and affects environmental sustainability in China. Conventional mitigation strategies focusing on reducing volatile organic compounds and nitrogen oxides (NOx) remain complex and challenging. Here, through field flux measurements and laboratory simulations, we observe substantial nitrous acid (HONO) emissions (FHONO) enhanced by nitrogen fertilizer application at an agricultural site. The observed FHONO significantly improves model performance in predicting atmospheric HONO and leads to regional O3 increases by 37%. We also demonstrate the significant potential of nitrification inhibitors in reducing emissions of reactive nitrogen, including HONO and NOx, by as much as 90%, as well as greenhouse gases like nitrous oxide by up to 60%. Our findings introduce a feasible concept for mitigating O3 pollution: reducing soil HONO emissions. Hence, this study has important implications for policy decisions related to the control of O3 pollution and climate change.

Emerging Role of p‐Block Element in Catalyzing Electrochemical NOx Reduction to Ammonia: A Theoretical Perspective

AbstractFixing earth‐abundant nitrogen elements into essential compounds is one of the ultimate issues for mankind. Electrochemical nitrogen fixation is regarded as promising to replace the Haber‐Bosch (HB) process at current stage. However, direct fixation of N2 is found skeptical recently due to the stable chemical properties of N2 molecule. In this regard, the more reactive nitrogen oxides (NOx) species came to light as an alternative of nitrogen sources. Since NOx species is one of the most prevalent pollutants in wastewater, it is also desired that NOx reduction can transform these detrimental ingredients into value‐added products such as ammonia. Like other chemical reactions, the performance of electrochemical NOx reduction to ammonia (eNOxRA) has a strong relation with the performance of catalysts. Previously, catalyst design of eNOxRA is dominantly based on transition metals. The role of p‐block elements in eNOxRA is not fully realized until very recent years. In this perspective, the up‐to‐date advances of p‐block‐contained catalysts in eNOxRA are concluded, with the role of p‐block elements specifically classified and discussed. Several strategies are also introduced to delicately investigate the interaction between p‐block elements and NOx species. At the end, some dilemmas and potential opportunities are proposed to achieve a more comprehensive understanding toward developing high‐efficient p‐block electrocatalyst for NOxRA.

Variability in the properties of the distribution of the relative humidity with respect to ice: implications for contrail formation

Abstract. Relative humidity with respect to ice (RHi) is a key variable in the formation of cirrus clouds and contrails. We document its probability density function (PDF) using long-term Measurements of Ozone, Water Vapour, Carbon Monoxide and Nitrogen Oxides by In-Service Airbus Aircraft (MOZAIC) and the In-service Aircraft for a Global Observing System (IAGOS) observations over the period 1995–2022 in the upper troposphere (UT) and the lower stratosphere (LS) between 325 and 175 hPa. The characteristics of the RHi PDF differ in the UT and in the LS of the high-latitude regions (HLs) and mid-latitude regions (MLs) of the Northern Hemisphere. In the LS, this PDF decreases exponentially with increasing RHi. In the UT, it first increases exponentially in subsaturated conditions and then decreases exponentially in supersaturated conditions. Because of these different behaviors, the PDF for the combined UT and LS is bimodal. In contrast to the HLs and the MLs, the RHi PDF in the tropical troposphere decreases exponentially with increasing RHi. The different forms of PDF, in the tropics and in the higher-latitude regions, lead to a global PDF of RHi in subsaturated tropospheric conditions that is almost uniform. These findings invite caution when using MOZAIC and IAGOS measurements to calibrate large-scale simulations of RHi. The variability in RHi properties associated with that of temperature also has implications for the formation of contrails. We examined the impact of switching fuel (from kerosene to bioethanol or liquid hydrogen) on the frequency of contrail formation using the Schmidt–Appleman criterion. We show that bioethanol and, to a larger extent, liquid hydrogen would produce more contrails. The impact of a potential change from kerosene to these alternative fuels decreases with decreasing pressure but increases when moving from the higher latitudes of the Northern Hemisphere to the tropics. Finally, we emphasize that investigations of the impact on contrail occurrence frequency as a result of switching from fossil kerosene to more sustainable fuels must be carried out in various meteorological conditions.

Evaluating the Performance and Practicality of a Multi-Parameter Assessment System with Design, Comparative Analysis, and Future Directions

This study introduces a developed environmental quality assessment system, detailing its hardware, software, and comparative analysis against a publicly available system. While showing larger deviations in particulate matter and air humidity parameters, the proposed system demonstrates sufficient accuracy in other environmental characteristics. It establishes a standardized operating procedure and evaluates uncertainty and quality assurance measures, ensuring reliability in environmental measurements. The system offers comprehensive capabilities, measuring parameters like total volatile organic compounds, carbon dioxide, temperature, humidity, particulate matter, noise, nitrogen oxides, sulfur oxides, ozone, and carbon monoxide, with real-time monitoring functions for detecting environmental changes. Its user-friendly interfaces, scalability, and potential integration with existing systems enhance its versatility and cost-effectiveness across diverse settings. This study underscores the need for future research to enhance accuracy, reliability, and real-time operability and explore integration with smart city initiatives and environmental management systems. Overall, the proposed system represents a promising advancement in environmental monitoring technology, facilitating comprehensive environmental quality assessment and management.

Observing low-altitude features in ozone concentrations in a shoreline environment via uncrewed aerial systems

Abstract. Ozone is a pollutant formed in the atmosphere by photochemical processes involving nitrogen oxides (NOx) and volatile organic compounds (VOCs) when exposed to sunlight. Tropospheric boundary layer ozone is regularly measured at ground stations and sampled infrequently through balloon, lidar, and crewed aircraft platforms, which have demonstrated characteristic patterns with altitude. Here, to better resolve vertical profiles of ozone within the atmospheric boundary layer, we developed and evaluated an uncrewed aircraft system (UAS) platform for measuring ozone and meteorological parameters of temperature, pressure, and humidity. To evaluate this approach, a UAS was flown with a portable ozone monitor and a meteorological temperature and humidity sensor to compare to tall tower measurements in northern Wisconsin. In June 2020, as a part of the WiscoDISCO20 campaign, a DJI M600 hexacopter UAS was flown with the same sensors to measure Lake Michigan shoreline ozone concentrations. This latter UAS experiment revealed a low-altitude structure in ozone concentrations in a shoreline environment showing the highest ozone at altitudes from 20–100 m a.g.l. These first such measurements of low-altitude ozone via a UAS in the Great Lakes region revealed a very shallow layer of ozone-rich air lying above the surface.

Insights into the Volatile Flavor Profiles of Two Types of Beef Tallow via Electronic Nose and Gas Chromatography–Ion Mobility Spectrometry Analysis

In the current study, an electronic nose (E-nose) and gas chromatography–ion mobility spectrometry (GC-IMS) were employed to investigate the volatile flavor compounds (VFCs) of intense flavor beef tallow (L) and ordinary beef tallow (P). The study results indicate that an E-nose combined with an LDA and GC-IMS combined with an OPLS-DA can effectively distinguish between the two types of beef tallow. Compared with ordinary beef tallow, the E-nose sensors of intense flavor beef tallow have stronger response signals to sulfides, terpenes, and nitrogen oxides. A total of 22 compounds contribute to making the flavor of intense flavor beef tallow more typical and richer; in contrast, ethyl acetate was the main aroma-active compound found in the ordinary beef tallow. Sulfur-containing compounds and terpenoids might be the key substances that cause sensory flavor differences between the two types of beef tallow. In conclusion, the results of this study clarify the characteristics and differences of the two types of beef tallow and provide an enhanced understanding of the differences in the flavors of the two types of beef tallow.

Atmospheric Oxidation Capacity Elevated during 2020 Spring Lockdown in Chengdu, China: Lessons for Future Secondary Pollution Control.

This study presents the measurement of photochemical precursors during the lockdown period from January 23, 2020, to March 14, 2020, in Chengdu in response to the coronavirus (COVID-19) pandemic. To derive the lockdown impact on air quality, the observations are compared to the equivalent periods in the last 2 years. An observation-based model is used to investigate the atmospheric oxidation capacity change during lockdown. OH, HO2, and RO2 concentrations are simulated, which are elevated by 42, 220, and 277%, respectively, during the lockdown period, mainly due to the reduction in nitrogen oxides (NOx). However, the radical turnover rates, i.e., OH oxidation rate L(OH) and local ozone production rate P(O3), which determine the secondary intermediates formation and O3 formation, only increase by 24 and 48%, respectively. Therefore, the oxidation capacity increases slightly during lockdown, which is partly attributed to unchanged alkene concentrations. During the lockdown, alkene ozonolysis seems to be a significant radical primary source due to the elevated O3 concentrations. This unique data set during the lockdown period highlights the importance of controlling alkene emission to mitigate secondary pollution formation in Chengdu and may also be applicable in other regions of China given an expected NOx reduction due to the rapid transformation to electrified fleets in the future.

Aluminum dynamics in nitrogen‐saturated Andisols in Tokyo

AbstractThe debate over whether forests around the Tokyo metropolitan area are nitrogen (N) saturation persists, as atmospheric N deposition in throughfall has decreased. This decrease is evidenced by a notable decline in samples collected in the 1990s (especially 1991–1992 and 1995). This decline can be attributed to a reduction in nitrogen oxide (NOx) emissions from automobiles. The acidity derived from N deposition can increase aluminum (Al) mobility. We conducted a monitoring study from September 2010 to December 2021 to elucidate the effects of decreased N deposition on Al concentrations and flux in a forested Andisol. Throughfall and soil‐percolated water samples were collected under stands of Japanese cedar and Japanese cypress in Hachioji, Tokyo (Field Museum Tamakyuryo). Major inorganic ions were determined by ion chromatography. Total Al concentrations were determined using atomic absorption spectrometry after concentration under acidic conditions. Aluminum and nitrate () concentrations were significantly correlated in the both Japanese cedar and Japanese cypress stands. In the case of the Japanese cedar stand, Al concentrations tended to decrease over time from November 2010 to May 2015. Based on stepwise multiple regression analysis, acid load associated with N transformation ([H+]load) was chosen as the sole factor affecting Al mobilization in the Japanese cedar stand. Decreased N deposition affects Al dynamics via a decrease in [H+]load.

Effect of CO2 Gasification on Nitrogen Oxide Emission in Oxy-Fuel Combustion.

Due to the cumulative effect of the recycled flue gas in oxy-fuel combustion, the reduction of NO has become the focus of research in which the role of CO2 gasification has a nonnegligible effect. In this article, the heterogeneous gasification mechanisms of CO2 on coal char during oxy-fuel combustion were studied by density functional theory and transition-state theory. The zigzag char model and char(N) model were selected to investigate the CO2 adsorption and gratification reactions at the molecular level. By comparison, the CO2 gasification reaction is preferred to occur on the zigzag char model with a reduction in the energy barrier and an increase in the reaction rate. When considering char nitrogen conversion, the gasification reaction is more prone to releasing NO first, leading to the contraction of the aromatic ring and the generation of CO at high temperatures. Therefore, the study further highlights the promoting role of CO2 gasification on the homogeneous and heterogeneous reduction of NO, which is mainly reflected in the reduction effect of CO. Moreover, it also accelerates the consumption of coal char and NO formation, which is favorable for the reduction reactions to a certain extent.

Impact of air pollution and climate change on mental health outcomes: an umbrella review of global evidence.

The impact of air pollution and climate change on mental health has recently raised strong concerns. However, a comprehensive overview analyzing the existing evidence while addressing relevant biases is lacking. This umbrella review systematically searched the PubMed/Medline, Scopus and PsycINFO databases (up to June 26, 2023) for any systematic review with meta-analysis investigating the association of air pollution or climate change with mental health outcomes. We used the R metaumbrella package to calculate and stratify the credibility of the evidence according to criteria (i.e., convincing, highly suggestive, suggestive, or weak) that address several biases, complemented by sensitivity analyses. We included 32 systematic reviews with meta-analysis that examined 284 individual studies and 237 associations of exposures to air pollution or climate change hazards and mental health outcomes. Most associations (n=195, 82.3%) involved air pollution, while the rest (n=42, 17.7%) regarded climate change hazards (mostly focusing on temperature: n=35, 14.8%). Mental health outcomes in most associations (n=185, 78.1%) involved mental disorders, followed by suicidal behavior (n=29, 12.4%), access to mental health care services (n=9, 3.7%), mental disorders-related symptomatology (n=8, 3.3%), and multiple categories together (n=6, 2.5%). Twelve associations (5.0%) achieved convincing (class I) or highly suggestive (class II) evidence. Regarding exposures to air pollution, there was convincing (class I) evidence for the association between long-term exposure to solvents and a higher incidence of dementia or cognitive impairment (odds ratio, OR=1.139), and highly suggestive (class II) evidence for the association between long-term exposure to some pollutants and higher risk for cognitive disorders (higher incidence of dementia with high vs. low levels of carbon monoxide, CO: OR=1.587; higher incidence of vascular dementia per 1 μg/m3 increase of nitrogen oxides, NOx: hazard ratio, HR=1.004). There was also highly suggestive (class II) evidence for the association between exposure to airborne particulate matter with diameter ≤10μm (PM10) during the second trimester of pregnancy and the incidence of post-partum depression (OR=1.023 per 1 μg/m3 increase); and for the association between short-term exposure to sulfur dioxide (SO2) and schizophrenia relapse (risk ratio, RR=1.005 and 1.004 per 1 μg/m3 increase, respectively 5 and 7 days after exposure). Regarding climate change hazards, there was highly suggestive (class II) evidence for the association between short-term exposure to increased temperature and suicide- or mental disorders-related mortality (RR=1.024), suicidal behavior (RR=1.012), and hospital access (i.e., hospitalization or emergency department visits) due to suicidal behavior or mental disorders (RR=1.011) or mental disorders only (RR=1.009) (RR values per 1°C increase). There was also highly suggestive (class II) evidence for the association between short-term exposure to increased apparent temperature (i.e., the temperature equivalent perceived by humans) and suicidal behavior (RR=1.01 per 1°C increase). Finally, there was highly suggestive (class II) evidence for the association between the temporal proximity of cyclone exposure and severity of symptoms of post-traumatic stress disorder (r=0.275). Although most of the above associations were small in magnitude, they extend to the entire world population, and are therefore likely to have a substantial impact. This umbrella review classifies and quantifies for the first time the global negative impacts that air pollution and climate change can exert on mental health, identifying evidence-based targets that can inform future research and population health actions.

Tracking social-economic system nitrogen flow in China for emissions reduction and efficiency improvement

The increasing human demand have driven intensive reactive nitrogen (Nr) use, leading to high emissions and low efficiency in entire social-economic system. Herein, we accomplished a social-economic Nr flow model to trace the multi-sectorial Nr use, efficiency, and emissions in China from 1980 to 2020. The results showed that Nr use intensity increased 3.1-fold within four decades, with the decreasing proportions of Nr recovery from 32.7 % to 16.8 %. The Nr use pathways of production, consumption and waste management stages showed low resources use efficiency in agriculture and industrial production, high degree of consumption loss, insufficient waste treatment characteristics currently. Nr emissions peaked in 2012 and declined 12.7 % to 2020 owing to the nitrogen oxides control and mitigating overuse of fertilizers, and will continuously decrease under strategies in 2040 (41.7 % compared with 2012), indicating the large potential for emission reduction and efficiency improvement in next few decades.

Method and application of surface modification of Cerium dioxide

Airborne pollutants, such as nitrogen oxides (NOx), and waterborne contaminants, including heavy metals, dyes, and other pollutants, pose substantial environmental threats and jeopardize human health. Additionally, certain limitations have hindered the widespread application of some batteries, primarily attributed to elevated operating temperatures and the decreasing use of fossil fuels. In response to these challenges, cerium dioxide (CeO2) nanoparticles have garnered considerable attention due to their unique and advantageous physical and chemical properties. Furthermore, the incorporation of CeO2 into various coating materials has demonstrated the potential to significantly enhance their performance. In the realm of biotechnology, research into CeO2 nanoparticles continues to expand, encompassing a range of applications such as the scavenging of reactive oxygen species (ROS) in biological systems, the development of anti‐inflammatory agents, and cancer research. Nevertheless, in these diverse applications, CeO2 still exhibits certain limitations that hinder the achievement of desired outcomes. The modification of CeO2 nanoparticles presents a promising avenue to address these limitations, thereby improving their overall efficacy. As such, this review aims to comprehensively compare and summarize various methods for the modification of CeO2 nanoparticles, elucidate their practical applications, and provide insights into the potential challenges and future prospects in this field.This article is protected by copyright. All rights reserved.

Water extraction in aero gas turbines for contrail mitigation

Abstract Water vapour and particles in aero engine exhaust can give rise to condensation trails (contrails) in the wake of aircrafts, and recent studies suggest that persistent contrails and contrail cirrus account for circa 50% of the total aviation-derived radiative forcing (RF). The Schmidt-Appleman criterion is widely used to qualitatively predict the formation of contrails. The criterion indicates that the formation of contrails is affected by both aero engine exhaust and ambient air conditions and can therefore provide the theoretical basis to devise contrail mitigation strategies and further allows quantitative assessment of these strategies. This work focuses on water extraction from the aircraft engine exhaust for contrail mitigation. The fuel water emission index ( ${\rm{E}}{{\rm{I}}_{{{\rm{H}}_2}{\rm{O}}}}$ ) is one of the key factors that determines whether persistent contrails form or not. It indicates the amount of water produced for every kg of fuel burnt. Research has indicated that water extraction from the exhaust of the aero engine has been considered for Nitrogen oxides (NOx) reduction, but not for contrail mitigation. Assuming that water extraction is indeed possible, the emphasis of this work will therefore be on understanding how much water is needed to be extracted for contrail mitigation depending on the altitude and the relative humidity (RH), with the aim to carry out a meaningful study on the mitigation of persistent contrails and contrail cirrus to enable a fast and considerable reduction in aviation-derived RF.

Digital disruption and energy efficiency: The impact of regional digitalization on China's industrial sector

Using the unique micro-data of industrial enterprises' Nitrogen oxides (NOx) and Sulfur oxides (SOx) emissions covering 58,725 enterprise-year observations, this paper investigates how digitalization affect energy efficiency. The empirical results show that regional digitalization can significantly promote the improvement of energy efficiency of industrial enterprises. Specifically, the result of PSM-DID method indicates that the impact of digitalization on energy efficiency is significantly enhanced by the “National innovative pilot cities” policy, while the dynamic result validates the continuity of industrial enterprises' energy efficiency. Moreover, regional digitalization has superior impact on enterprises within eastern region enterprises, the manufacturing sector, and with elevated liquidity and profitability levels. Finally, moderating effect suggests that technological innovation expand the positive impact of digitalization on enterprises’ energy efficiency. This study confirms regional digitalization can promote the energy efficiency of Chinese industrial enterprises, providing the policy suggestions to the energy transition in China.

Quality of Carbon Emissions Disclosure on Corporate Sustainability Report Gojek Period 2020 and Goto Period 2021 – 2022

The high level of air pollution which is increasing from year to year causes air quality to decline. One of the causes of the increase in air is the growth in the number of motorized vehicles which causes an increase in the amount of emissions released in the form of Carbon Monoxide (CO), Hydrocarbons (HC), Nitrogen Oxide (NO). This shows that climate change is occurring. Climate change is one of the environmental problems that is currently of concern to stakeholders. The Carbon Disclosure Project (CDP) is a non-profit organization that operates focused on addressing environmental issues. CDP works by publishing information sheets which are useful as a guide for companies to disclose greenhouse gas (GHG) emissions resulting from the company's business activities. The company publishes a sustainability report which reveals carbon emissions. GoTo is a merger between Gojek and Tokopedia where in 2020 Gojek published a sustainability report. Scoring of carbon emission disclosures both quantitatively and qualitatively was carried out in this research. During the 2020-2021 period, the highest level of suitability and quality of disclosure was obtained by GoTo. Quantitatively, the climate change category has high disclosure quality. Qualitatively, the GHG emissions calculation category has the highest disclosure quality.

Measurement-based carbon intensity of US offshore oil and gas production

Abstract The United States (US) produces oil and gas from six offshore regions: the North Slope of Alaska, Cook Inlet in Alaska, offshore California, and three Gulf of Mexico (GOM) sub-regions: state shallow, federal shallow, and deep waters. Measurement-based assessment of direct greenhouse gas emissions from this production can provide real-world information on carbon emissions to inform decisions on current and future production. In evaluating the climate impact of production, the Carbon Intensity (CI, the ratio of greenhouse gases emitted compared to the energy of fuels produced) is often used, though it is rarely quantified with measurements. Here, we complete an observational evaluation of the US offshore sector and present the largest current set of measurement-based CIs. We collected airborne measurements of methane, carbon dioxide, and nitrogen oxides from the North Slope, Cook Inlet, and California and combined with prior GOM results. For Alaska and California, we found emissions agree with facility-level inventories, however, the inventories miss some facilities. The US offshore CI, on a 100-year GWP basis, is 5.7 gCO2e/MJ[4.5, 6.8, 95% confidence interval]. This is greater than double the CI based on the national US inventory, with the discrepancy attributed primarily to methane emissions from GOM shallow waters, with a methane dominated CI of 16[12, 22] for GOM federal shallow waters and 43[25-65] for state shallow waters. Regional intensities vary, with carbon dioxide emissions largely responsible for CI on the North Slope 11[7.5, 15], in Cook Inlet 22[13, 34], offshore California 7.2[3.2, 13], and in GOM deep waters 1.1[1.0, 1.1]. These observations indicate offshore operations outside of the GOM in the US have modest methane emissions, but the CI can still be elevated due to direct carbon dioxide emissions. Accurate assessment of different offshore basins, with differing characteristics and practices, is important for the climate considerations of expanded production.

Automatic Fuel Flow Regulation System for the Combustion Chamber under Varying Operating Conditions Based on a Neural Nitrogen Oxide Sensor

Automatic Fuel Flow Regulation System for the Combustion Chamber under Varying Operating Conditions Based on a Neural Nitrogen Oxide Sensor

Effects of Ethanol addition to Diesel-Biodiesel blends on the CI engine characteristics

Effects of Ethanol addition to Diesel-Biodiesel blends on the CI engine characteristics