Journal of Atmospheric Chemistry最新文献

A severe air pollution episode occurred in Huangshi City, central China, during February 2024, coinciding with intensive Spring Festival fireworks. To investigate the chemical processes, PM₂.₅ mass and water-soluble inorganic ions (WSIIs) were analyzed in conjunction with ionic balance, correlation, and backward trajectory models. The episode exhibited three distinct phases. In the pre-pollution stage (February 5–8), PM₂.₅ remained stable around 60 µg/m³, with secondary inorganic aerosols (NO₃⁻, SO₄²⁻, NH₄⁺) as the major components under humid and stagnant conditions conducive to secondary aerosol formation. During the pollution peak (February 9–10), concentrations approached 800 µg/m³ due to firework emissions and stagnant conditions. Ion composition shifted markedly, with sharp increases in K⁺, Cl⁻, and Mg²⁺, concurrent decreases in NO₃⁻ and NH₄⁺, and a low neutralization ratio, indicating strongly acidic aerosols dominated by fireworks-derived sulfate. Ozone depletion further suppressed photochemistry and secondary aerosol production. In the post-pollution stage (February 11–14), improved dispersion and reduced emissions lowered PM₂.₅ to background levels, while NO₃⁻ and NH₄⁺ rebounded and dust-related ions (Ca²⁺, Mg²⁺) increased. Backward trajectory clustering revealed that northern transport contributed during the clean phase, local stagnation dominated the pollution peak, and mixed inflows supported atmospheric cleansing thereafter. These findings demonstrate that episodic fireworks can significantly reshape aerosol composition and acidity, with meteorological conditions determining the severity of pollution episodes.

Carbonaceous components, including organic carbon (OC) and elemental carbon (EC), are critical constituents of Fine Particulate Matter (PM_2.5) as these components can significantly impact the local environment, climate, and human health. The present study aims to measure PM_2.5 and its carbonaceous content (OC and EC) in close proximity to the Taj Mahal during the winter period of January to February 2022. The estimated average mass concentration of PM_2.5 was 154.2 ± 65.4 µg/m³. This level is alarmingly high, being almost 2.5 times greater than the daily standard (60.0 µg/m³) set by the National Ambient Air Quality Standards (NAAQS) of India and a staggering 10 times higher than the World Health Organization (WHO) guidelines (15.0 µg/m³). Such elevated levels of PM_2.5 indicate severely degraded air quality in the area, posing significant risks to both the environment and human health. The concentrations of OC and EC were found to be 19.8 ± 7.8 µg/m³ and 8.11 ± 2.81 µg/m³, respectively. These value underscore the predominance of carbonaceous aerosols in the local atmosphere. OC and EC are found to be positively corelated with each other indicating their emission from similar sources. The eight carbon fraction analysis of PM_2.5 shows that biomass burning and road dust were the main sources of emission at sampling site. The average concentration of primary organic carbon (POC) was 14.67 µg/m³ whereas secondary organic carbon (SOC) was recorded as 5.55 µg/m³, highlighting that organic carbon in the region is contributed by both primary sources and secondary processes, including the condensation or adsorption of organic compounds.

Air pollution is a critical environmental issue influenced by both natural and anthropogenic sources. We hypothesized that PM_2.5 chemical composition varies spatially due to local anthropogenic sources, soil resuspension, and biomass burning. This study analyzed particulate matter (PM_2.5) concentrations and chemical composition (black carbon (BC), elements, and ions) in three locations in Rio de Janeiro state: Gávea (urban area), PARNASO (environmental preservation area), and Campos dos Goytacazes (urban with burning biomass). The results show that PM_2.5 concentrations varied significantly among the sampled sites, with the average highest values recorded in PARNASO (20 ± 13 µg m^− 3), followed by Gávea (12 ± 7 µg m^− 3), and Campos (8 ± 4 µg m^− 3). Although no daily samples exceeded Brazilian air quality standards, 23% surpassed WHO guidelines. Fe and Al were the most abundant elements in all sites, indicating strong soil resuspension influence, with higher concentrations in Campos. BC was higher in PARNASO (2.2 ± 0.9 µg m^− 3) but contributed more to PM_2.5 in Campos (22–24%), highlighting the biomass-burning influence. Water-soluble ions, particularly Cl⁻, Na⁺, SO₄²⁻, and NO₃⁻, were predominant across all sites, with K⁺ showing statistical differences between seasonality in Campos. A Principal Component Analysis (PCA) identified soil resuspension, vehicular emissions, and biomass burning as major contributors to PM_2.5 pollution. These findings underscore the necessity for region-specific air quality policies and continuous monitoring, emphasizing their global relevance for effective long-term pollution mitigation in urban, and preserved areas.

Fine particulate matter (PM_2.5) can pose serious health effects. Therefore, continuous monitoring of PM_2.5 is vital for public health management. This study aims to investigate PM_2.5 pollution in Türkiye in the period before ground-level measurements, both temporally and spatially. Satellite-based PM_2.5 mapping was implemented to overcome gaps in ground-level measurements. The method of van Donkelaar et al. (2010), which combines satellite-derived aerosol optical depth (AOD) and aerosol profiles from the GEOS-Chem model, was applied. The global annual surface fine particulate matter concentration dataset (V4.GL.03) was used for 1998–2019. The unsupervised trend clustering method is applied to determine the trends in PM_2.5. Health risks were assessed using Population Exposure (PE) model. The interannual average concentrations of PM_2.5 in Türkiye ranged between 13.0 and 18.0 µg/m³ with a mean of 15.2 µg/m³. The highest level of particulate matter pollution was recorded in the provinces of Bursa and Kütahya. PM_2.5 concentrations showed a growth trend in nearly 90% of Türkiye. The findings provide critical information on air quality management and public health. Based on observed concentration trends and population exposure, urgent policy attention should focus on controlling PM_2.5 pollution in Bursa, Kütahya, Ankara, İzmir, Kocaeli, Adana, and Antalya provinces. Decision-makers should take the necessary precautions to cope with PM_2.5 pollution. Furthermore, Türkiye must set the PM_2.5 thresholds as soon as possible.

In the present study, production and loss pathways of tropospheric ozone and their rates are identified by an algorithm for the automatic determination of reaction pathways in complex chemical systems. For this purpose, reaction rates were provided by the chemistry-transport model IFS(MOZART) (Integrated Forecasting System - Model for Ozone and Related chemical Tracers). A detailed analysis is carried out for three different scenarios: clean air (Palau), intermediate emissions (Athens), and large emissions (Beijing). At each location the processes at the surface and at an altitude of 500 m are analysed. The ozone production rate is largest in Beijing, intermediate in Athens and smallest on Palau. Nevertheless, there is net ozone loss at the surface in Beijing because of a strong net conversion of ozone to NO(_{varvec{2}}) by freshly emitted NO. The ozone production is dominated by methane oxidation on Palau and by the oxidation of short-lived, i.e. emitted nearby, VOCs (volatile organic compounds) in Beijing, where the strongest individual contributor at the surface is isoprene. Athens represents an intermediate situation. The pathways determined show in detail all intermediate steps of the degradation of individual VOCs, including the interaction with NO(_{varvec{x}}) and HO(_{varvec{x}}) species, and permit the calculation of the number of ozone molecules formed per VOC molecule consumed. For instance, at the surface in Beijing the average net production of ozone in pathways leading to the full degradation of isoprene (to CO(_{varvec{2}})) is 10.1 ozone molecules per isoprene molecule consumed. At the same location pathways producing up to 18 ozone molecules per isoprene molecules have been found. However, the rates of these extreme pathways are very small.

Brominated and iodinated methanes impact atmospheric chemistry, particularly through ozone depletion, but the environmental factors controlling their production by marine phytoplankton are not fully understood. This study examined how different light intensities (30, 60, 90, and 120 µmol photons m^− 2 s^− 1) affect the growth and halomethane production by the marine diatom Achnanthes subconstricta. Cultures were incubated under full-spectrum light, and concentrations of CHBr₃, CHBr₂Cl, CHBrCl₂, CH₂I₂, CH₂ClI, and CH₂BrI were measured using purge-and-trap gas chromatography–mass spectrometry. Phytoplankton growth, assessed by chlorophyll a concentration, increased with light intensity. Among brominated methanes, CHBr₃ and CHBr₂Cl were generally more abundant, and CHBrCl₂ was least abundant. Similarly, CH₂I₂ was generally the dominant iodinated methane, followed by CH₂ClI and CH₂BrI. The production rate ratios of CHBr₃ : CHBr₂Cl : CHBrCl₂ and CH₂I₂ : CH₂ClI : CH₂BrI were 1.8 : 1.7 : 1 and 5.2 : 2.0 : 1, respectively, at 120 µmol photons m^− 2 s^− 1 during the exponential phase. CHBr₃ production rates normalized to chlorophyll a were 2.13, 3.12, 9.49, and 7.24 nmol (g chlorophyll a)⁻¹ d^− 1 at 30, 60, 90, and 120 µmol photons m^− 2 s^− 1, respectively. Similarly, CH₂I₂ production rates normalized to chlorophyll a were 5.47, 2.53, 10.5, and 29.8 nmol (g chlorophyll a)⁻¹ d^− 1 at the same light intensities. These results demonstrate that halomethane production in A. subconstricta is markedly affected by light intensity, with distinct patterns observed for different compounds. The findings suggest that A. subconstricta may play a significant role in marine halocarbon emissions, with production that varies depending on light conditions and growth phase. 

Environmental pollution due to fine particulate matter (particulate matter ≤ 2.5 μm; PM_2.5) is a major health concern worldwide, especially in India. In the post-monsoon and winter seasons, meteorological conditions favor the confinement of aerosols, leading to higher concentrations of PM_2.5 in the Indo-Gangetic Plain (IGP). Scientific research has associated PM_2.5 exposure with various causes of premature mortality, including ischemic heart disease (IHD), chronic obstructive pulmonary disease (COPD), and lung cancer (LC). This study investigates spatial and temporal variability and transport of particulate matter (utilizing the airmass back trajectory analysis) over six states in the IGP to gain insights into their origin and transport, during the most polluted (post-monsoon and winter) seasons. Among all monitored locations, Delhi reported the greatest PM_2.5 loading during the winter and post-monsoon seasons (170.47 ± 84.80 µg m⁻³), followed by Patna, Bihar (130.47 ± 61.97 µg m⁻³). Using the Integrated Exposure–Response (IER) model, our analysis indicates that annual exposure to PM_2.5 could lead to more than 3,000 premature deaths per million people in each city, based on the WHO guideline limits. This study presents a comparative assessment of PM concentrations and the associated mortality risks across six states of the Indo-Gangetic Plain (IGP), with two monitoring sites in each state. The findings provide valuable insights to support policymakers in developing effective air quality management and mitigation strategies.

Graphical abstract

Atmospheric simulation chambers (ASCs) are one of the most advanced tools for the experimental investigation of the oxidation of volatile organic compounds (VOCs) and the subsequent secondary organic aerosol (SOA) formation. Toluene is one of the most prevalent anthropogenic VOCs. Its photo-oxidation yields a wide range of products in the gas phase and a significant amount of SOA. Some of the remaining uncertainties about toluene atmospheric chemistry are possibly linked with chamber artifacts. In this study, several atmospheric simulation chambers, characterized by a great diversity (size, shape, material of walls, light source, instrumentation, measurement techniques, etc.), performed several toluene photo-oxidation experiments under different pre-set conditions (levels of toluene, NO_x, and relative humidity, presence, or lack of seeds). A model based on the Master Chemical Mechanism (MCM) and a SOA production module were used to facilitate the synthesis of the results. The results of the multiple-chamber toluene experiments suggest that a combination of facilities can provide a better picture of the overall behavior and that significant gaps remain in our understanding of the system, especially in the later oxidation stages. For cresol, a first-generation product, the observed gas-phase yields, ranging from 3% to 8% under low-NO_x conditions, were consistent with model predictions. In contrast, the measured gas-phase yields of benzaldehyde (8–16%%) were higher than the predicted (3–5%) yields, highlighting uncertainties in the H-abstraction pathway of the toluene reaction with hydroxyl radicals (OH). Glyoxal and methylglyoxal yields varied between facilities, with the model often failing to capture their temporal profiles. Additionally, the MCM-based model struggled to reproduce concentrations of oxygenated products (e.g., C₇H₈O₂ and C₇H₈O₃), suggesting shortcomings in simulating later oxidation stages. Most notably, the model consistently underpredicted SOA mass across experiments, pointing to critical gaps in the representation of SOA-forming pathways in the currently used version of the MCM.

Nitrate (NO₃^–) levels in air pollution have shown a sustained increase across eastern China. However, the key drivers behind rising surface NO₃^– concentrations remain unclear, posing challenges for targeted pollution control strategies. PM_2.5 samples were collected from September 2015 to August 2016 at both urban and suburban sites in Nanjing, a megacity in the Yangtze River Delta (YRD), for compositional analysis and source apportionment. The measured annual mean PM_2.5 concentration was 96.8 ± 46.0 µg m^–3. The positive matrix factorization model identified four primary PM_2.5 sources in Nanjing: secondary nitrate (19.4%), secondary sulfate (36.8%), coal and biomass burning (40.6%), and industrial emissions (3.2%). Water-soluble secondary inorganic aerosols (NO₃^–, SO₄^2–, NH₄⁺) dominated PM_2.5 composition, accounting for 92.7% of ionic components and 37.0% of total mass. NO₃^– concentrations exhibited significant increases in both absolute and relative terms as PM_2.5 pollution levels rose, suggesting its important role in PM_2.5 pollution. The results indicate that NO₃^– formation is enhanced under ammonia-rich conditions with low temperatures, high humidity, and elevated acidity. Policy-driven reductions in SO₂ and NO_x, without simultaneous NH₃ control, may have contributed to ammonia-rich conditions that facilitated NO₃^– formation, leading to NO₃^–-dominated PM_2.5 pollution in the YRD. Therefore, our results indicate that coordinated control of both nitrogen oxides and ammonia emissions may be necessary to mitigate NO₃^–-driven PM_2.5pollution.

Graphical abstract

This study investigates the concentration and variation of key air pollutants SO₂, NOx, PM₁₀, and PM₂.₅ from 2009 to 2022 in Thiruvananthapuram, a city relatively free from industrial activities. SO₂ levels consistently remained well below the National Ambient Air Quality Standards whereas, PM₁₀ levels rose significantly, and often exceeded permissible limits. ICP-MS analysis revealed that Na, Zn, and Ca constitute up to 60% of the PM₁₀ mass, with major sources including sea salt, vehicular emissions, and construction activities. SEM and EDS analyses indicated a significant presence of carbonaceous particles and trace elements like Ba and Zn, which are linked to vehicular emissions and pose severe health risks. The presence of black carbon (BC) and organic carbon further underscores the contribution of transportation to air pollution. These findings are found to be consistent with broader national and global air quality challenges. The rising PM₁₀ levels mirror trends observed in other Indian cities, where urbanization and vehicular emissions remain the primary pollution sources. On a global scale, the presence of hazardous pollutants such as BC and heavy metals in urban environments is a critical public health concern. This study underscores the urgent need for targeted local air quality management strategies that align with national and global efforts to mitigate air pollution and protect public health.