Isoprene is one of the most abundant biogenic volatile organic compounds (BVOCs) emitted by plants and plays a key role in atmospheric chemistry. However, seasonally resolved, species-specific outdoor enclosure-based sapling measurements in tropical ecosystems remain scarce. In this study, isoprene emission rates from sixteen dominant tropical tree species in Central India were characterized across summer, rainy, and winter seasons using a dynamic enclosure chamber with potted saplings at GGV Campus, Bilaspur. Isoprene emissions peaked in summer, contributing 52
Size-fractionated particulate matter analysis is key to understanding how particle size influences health risks. However, data on metals distribution and respiratory deposition across PM sizes in Southeast Asia is still scarce. In this study, we evaluated the levels, size distribution, and health-related impacts of metals in particulate matter (PM) from Ho Chi Minh City (HCMC), the most densely populated urban in Southern Vietnam. Sampling was performed monthly with a five-stage nano-sampler (PM< 0.5, PM0.5−1, PM1−2.5, PM2.5−10, and PM> 10). Concentrations of 8 metals were analyzed by ICP-MS, and the levels were observed in the following order: Al (1741 ng m− 3) > Fe (958 ng m− 3) > Zn (731 ng m− 3) > Pb ( 22.6 ng m− 3) > Mn (21.3 ng m− 3) > Cu (19.4 ng m− 3) > Ni ( 4.86 ng m− 3) > Cd (0.52 ng m− 3). Crustal metals (Al and Fe) predominantly resided in the coarse particulate fraction, whereas anthropogenic metals (e.g. Pb, Zn, and Cd) were enriched in fine particles. Deposition modeling indicated that crustal metals were mostly retained in the head region (62–72
PM2.5 is associated with multiple adverse health outcomes, yet data on its concentration, composition and sources in African cities remain limited. This study presents the first detailed characterisation of outdoor PM2.5 in Johannesburg, South Africa. Twenty-four-hour filter samples were collected every sixth day from 3 October 2020 to 12 October 2021 at a residential site in the suburb of Buccleuch. Samples were analysed using gravimetric methods, smoke-stain reflectometry, optical transmissometry and X-ray fluorescence. Source contributions were assessed using principal component analysis (PCA), enrichment factor (EF) analysis and Hybrid Single Particle Lagrangian Integrated Trajectory model for backward trajectories. The mean PM2.5 concentration was 8.1 µg.m−3(range: 0.04–30 µg.m−3), exceeding the World Health Organization (WHO) annual guideline (5 µg.m−3). Daily concentrations surpassed the WHO daily guideline (15 µg.m−3) on seven of the 55 sampling days. Mean black carbon (BC) and organic carbon (OC) concentrations were 0.51 and 0.46 µg.m−3, respectively. Twelve trace elements were detected, with Fe, K, S and Si most abundant. PM2.5, BC, OC and several elements were significantly higher in winter and autumn, reflecting increased combustion activities and unfavourable meteorological conditions. Trajectory analysis indicated contributions from regional mining and coal-related activities. Integrated PCA and EF results showed that PM2.5 comprised resuspended dust, traffic-related non-exhaust emissions, local residential combustion and regionally transported pollution. These findings highlight multi-source exposure and the need for coordinated air quality management at municipal and regional scales.
Satellite data from the Sentinel-5P/TROPOMI sensor are used to monitor major air pollutants across Rajasthan in a consistent way. This study uses these observations to examine trends in six pollutants (NO2, SO2, CO, O3, CH4 and HCHO) from 2018 to 2024 and to find statistically significant hotspot areas. An Analytic Hierarchy Process (AHP) is applied to assign weights to the six pollutants after checking that the consistency ratio is within the accepted limit (CR ≤ 0.10). The weighted layers are combined to create a Composite Burden (CB) map. Hot and cold spots are then detected using the Getis–Ord Gi* statistic, based on a regular grid, an optimized neighborhood distance, row-standardized spatial weights, and false-discovery-rate correction. The state-level trend analysis shows that ozone (O3) and methane (CH4) are increasing steadily and significantly during the study period. Sulfur dioxide (SO2) shows a small decline, while nitrogen dioxide (NO2), carbon monoxide (CO) and formaldehyde (HCHO) show only small or non-significant changes. The CB and Gi* results highlight three main hotspot belts. The first is in the northern canal region, including Sri Ganganagar, Hanumangarh and Churu. The second follows the north-eastern industrial and transport corridor from Khairthal–Tijara through Bhiwadi, Neemrana, Kotputli, Behror, Alwar, Bharatpur and Dholpur. The third lies in the south-central and south-eastern industrial belt around Chittorgarh and the Kota–Baran–Jhalawar region, where many power plants and cement units are located. District-level analysis also shows similar increases in O3 and CH4 across major urban and industrial centres. This combined AHP and Gi* approach gives a clear, decision-oriented picture of Rajasthan’s multi-pollutant burden and points to priority regions for actions such as NOₓ/VOC control, SO2 reduction at large point sources, and CH4 management in agricultural and waste-rich districts.
This study investigates the characteristics, sources, and health risks of particulate-bound mercury (PBM) in PM₂.₅ from a suburban site in Nanjing, within the Yangtze River Delta, China. Seasonal sampling conducted in 2019 revealed a mean PBM concentration of 106 ± 115 pg/m³, with the highest levels in autumn. The PBM/PM₂.₅ ratio indicated significant anthropogenic influence. The estimated annual dry deposition flux of PBM was 39.86 µg/m²/yr. Health risk assessment determined that the non-carcinogenic risks from PBM exposure were below the safety threshold (Hazard Index < 1) for both children and adults. However, children were found to be more vulnerable, with risk levels approximately 11 times higher than adults, primarily through the ingestion pathway. Back-trajectory analysis indicated that air masses influencing the site originated from local, regional, and long-range sources. The findings underscore that while current PBM levels pose minimal immediate health risks, the heightened susceptibility of children and the significant dry deposition flux warrant continued monitoring and further investigation into the complete atmospheric mercury cycle in this economically vital region.
Tropospheric ozone (O3) pollution in urban regions has fueled numerous studies due to its far-reaching impacts on health, agriculture, and the climate. In this study, the variability of surface O3 and the roles of distinct physical and chemical drivers were investigated at a tropical coastal semi-urban site in southern peninsular India using observations collected from February 2021 to February 2023. The results revealed higher mean O3 concentrations during premonsoon due to stronger photochemistry. The lower seasonal amplitude (24
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 (PM2.5) as these components can significantly impact the local environment, climate, and human health. The present study aims to measure PM2.5 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 PM2.5 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 PM2.5 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 PM2.5 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.
Fine particulate matter (PM2.5) can pose serious health effects. Therefore, continuous monitoring of PM2.5 is vital for public health management. This study aims to investigate PM2.5 pollution in Türkiye in the period before ground-level measurements, both temporally and spatially. Satellite-based PM2.5 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 PM2.5. Health risks were assessed using Population Exposure (PE) model. The interannual average concentrations of PM2.5 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. PM2.5 concentrations showed a growth trend in nearly 90
Air pollution is a critical environmental issue influenced by both natural and anthropogenic sources. We hypothesized that PM2.5 chemical composition varies spatially due to local anthropogenic sources, soil resuspension, and biomass burning. This study analyzed particulate matter (PM2.5) 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 PM2.5 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
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 _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 _x and HO _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 _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; PM2.5) 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 PM2.5 in the Indo-Gangetic Plain (IGP). Scientific research has associated PM2.5 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 PM2.5 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 PM2.5 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.
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, NOx, 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
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. PM2.5 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 PM2.5 concentration was 96.8 ± 46.0 µg m–3. The positive matrix factorization model identified four primary PM2.5 sources in Nanjing: secondary nitrate (19.4 PM2.5 concentrations and sources in Nanjing were investigated from many perspectives. Precursors, meteorology, aerosol acidity impact secondary inorganic aerosol formation. Nitrate drives PM2.5formation and as the dominant component during severe pollution period. Ammonia-rich environment enhances nitrate formation in PM2.5.
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
Ozone (O3) and carbon dioxide (CO2) critically influence climate change through complex interactions with terrestrial vegetation. Ground-level O3 forms via NOx and VOCs photochemistry, while CO2 primarily comes from fossil fuel combustion. Their atmospheric concentrations interact through physicochemical processes: elevated CO2 levels may accelerate photochemical reaction rates of O3 precursors due to climate warming, while O3, as a potent oxidant, alters atmospheric oxidation capacity and consequently affects the lifetime of other greenhouse gases. Plant stomata serve as the primary interface for gas exchange between terrestrial ecosystems and the atmosphere, playing a critical role in regulating O3 uptake and CO2 assimilation. Plants simultaneously uptake CO2 for photosynthesis and absorb O3 through stomata. Interestingly, rising CO2 concentrations induce partial stomatal closure, thereby reducing O3 uptake. Conversely, elevated O3 concentrations entering stomata trigger oxidative stress responses in plants, leading to decreased stomatal conductance. While this defensive mechanism limits further O3 absorption, it simultaneously restricts CO2 uptake efficiency, ultimately impairing photosynthetic performance and carbon sequestration capacity. This review investigates the ecological effects of O3 and CO2 interactions, focusing on vegetation-mediated gas exchange and its feedback on atmospheric composition. This review examines flux monitoring technologies and modeling approaches, highlighting how O3 pollution influences CO2 assimilation and how plant responses contribute to atmospheric O3 regulation. Key factors such as species traits, growth conditions, and environmental variables are analyzed to evaluate how they modulate these interactions. By synthesizing current understanding of vegetation-regulated O3 and CO2 interactions, this study provides important insights for pollution control and sustainable ecosystem management.
Oligomeric hydroperoxides, including stabilized Criegee intermediates generated during isoprene ozonolysis, play an important role in new particle formation (NPF). In this study, we experimentally determined the relative abundance (ΦNPF) of new particles formed during isoprene ozonolysis, competing against the growth of preexisting particles. The number concentration of newly formed particles (NNPF) during isoprene ozonolysis was derived by comparing the size distribution of secondary organic aerosols (SOAs) in the presence of seed particles with that under humid conditions (relative humidity (RH) > 20
The Hunga Tonga-Hunga Ha’apai volcanic eruption in January 2022 injected an extraordinary amount of water vapour into the tropical stratosphere (estimated at 150 Tg) along with a modest injection of sulphur dioxide (estimated at 0.4 Tg). Using a suite of ground-based remote-sensing trace gas measurements located at Arrival Heights, Antarctica (78 S, 167E), along with co-located satellite measurements of water vapour and stratospheric aerosol optical depth, we observed the evolution of the 2023 ozone hole. Arrival Heights was located beneath the polar vortex for extended periods during the austral spring (late August to early December) 2023. Within this period, satellite measurements of lower stratospheric water vapour above Arrival Heights fall within climatology norms (2004–2023) while elevated (70
Atmospheric fine particulate matter (PM2.5) constitutes a major component of organics, inorganic and heavy toxic elements which is increasingly recognized as a significant factor of the tropospheric chemistry of planet Earth due to its ability to influence the planet’s radiative balance. In recent years, PM2.5 have been associated with declining air quality, negatively impacting both human health and the climate. Understanding the sources and behaviour of aerosols, both primary and secondary, as well as their spatial and temporal distribution, it is essential to evaluate their impact on air quality and climate. In the present study, a total 798 PM2.5 samples were collected and examined for their chemical speciation [carbon contents (OC and EC), inorganic ionic species (NH4+, Cl-, NO3- and SO42-) and elemental contents (Si, Ti, al, Fe, Zn, Cu, Mn, Pb, As, Br, Cr, Mo and P)] at metropolitan site of Delhi over the period of January 2013 to December 2021. On the basis of long-term analysis, the mean concentrations of total carbon contents (OC:15.5 ± 8.5 µg m-3 and EC: 7.0 ± 3.9 µg m-3), ionic species (Σ ionic species: 35.6 ± 25.6 µg m-3) and elements (Σ elements:17.2 ± 8.2 µg m-3) were estimated to be 18
