Journal of Atmospheric Chemistry最新文献

Ozone (O₃) and carbon dioxide (CO₂) critically influence climate change through complex interactions with terrestrial vegetation. Ground-level O₃ forms via NO_x 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 (Φ^NPF) of new particles formed during isoprene ozonolysis, competing against the growth of preexisting particles. The number concentration of newly formed particles (N^NPF) 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%) at the same reaction time. The number concentration of particles that took up semi-volatile organic compounds (N^uptake) was estimated from the difference in the size distribution between particle wall loss (PWL)-considered seed particles and SOAs with seed particles under humid conditions. The Φ^NPF was then calculated using the formula: N^NPF/(N^NPF + N^uptake) under different conditions. The methodology to determine the N^NPF was generally successful, whereas the determination of N^uptake was complicated due to the instability of PWL in the small Teflon bag experiments. The Φ^NPF can be represented as a product of the r^NPF(RH), the relative abundance of new particles formed during isoprene ozonolysis as a function of RH, and the ϕ^NPF(dry), the Φ^NPF value obtained under dry conditions. The obtained r^NPF(RH) values suggested that NPF can occur only under very limited RH conditions (RH < 10%) of isoprene ozonolysis in the atmosphere, but the products from the reaction of isoprene with O₃, probably Criegee intermediate oligomerization products, were found mainly to contribute to NPF.

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% increase in September mean sAOD), but highly variable, levels of stratospheric aerosol optical depth were observed. Ground-based measurements (total and partial columns) of ozone, ClO, HCl, ClONO₂, OClO, NO, NO₂ and HNO₃ throughout springtime show no measurable attributable impact of Hunga Tonga-Hunga Ha’apai water vapour on stratospheric chemical composition, and ozone depletion within the polar vortex. Prolonged denitrification and elevated levels of chlorine monoxide in the second half of September were caused by unseasonally low stratospheric temperatures. Contemporary TOMCAT 3-D chemical transport model simulations are in overall good agreement with observations. The model simulations indicate Hunga Tonga-Hunga Ha’apai water vapour caused an additional reduction in total column ozone of 5 -7 DU over Arrival Heights in spring and early summer within the polar vortex. Such small differences are not discernible using the current measurement dataset given atmospheric variability, measurement precision and observational gaps. The simulations indicate the largest additional reduction in total column ozone were in the polar vortex collar region, where increased water vapour loading caused additional ozone loss up to 13 DU over Arrival Heights.

In this study, the weekly total water-soluble inorganic ions (TWSII) concentrations of PM_2.5 in the coastal city of Algeria, Bou-Ismail, were determined from December 29th, 2013, to June 29th, 2014, under the ChArMEx project. This study aimed to identify the seasonal sources and chemical composition of PM2.5-bound water-soluble inorganic ions (WSIIs) in a coastal city of Algeria using principal component analysis (PCA). The findings indicated that the TWSII concentration was 14.06 ± 0.22 µg m⁻³ during the winter and 12.35 ± 0.42 µg m⁻³ during the spring. The Na⁺, NH₄⁺, NO₃⁻, and Cl⁻ ions were the main TWSII in winter, whilst Na⁺, NH₄⁺, oxalate, and NO₃⁻ ions were the main WSII in spring. PCA identified two sources for winter: PC1 is a mix of pollutants from secondary organic traces, marine sources, and stationary emissions from burning, while PC2 encompasses operations, construction materials, and secondary gas-particle transformations. For spring, four sources were identified: PC1, marine aerosol emissions; PC2, stationary emissions, agricultural practices, marine biogenic emissions, and biomass burning; PC3, photochemical response; and PC4, soil dust. The whole sample campaign had a 1.29 cationic-to-anionic regression slope. The [NO₃⁻]/[SO₄²⁻] mass ratio was greater than (1) The findings indicated the strong influence of pollutants from mobile sources over stationary sources. Pathway 1 includes all west and northwest air masses from the sample location. Large air masses traverse the Atlantic via Spain, Portugal, southern France, and western Algeria. An air mass from the south traversed the Algerian Desert and southern Libya in Pathway (2) In pathway 3, northwest Italy and Tunisia across the Mediterranean Sea were the most polluted.

Fuel composition and fuel type are crucial in determining the evaporative and combustion process emissions. This study examines the composition of Volatile Organic Compounds (VOCs) in the liquid fuel and headspace vapour of three commercially available regular and premium grade gasoline in India. More than 200 compounds were detected in the liquid samples, and 32 compounds were chosen as the target compounds based on the literature. The liquid normal grade fuel composition showed dominance of aromatics, accounting for about 50–64% of the total compounds, followed by isoparaffins (12–17%), paraffins (8–12%), naphthenes (4.5-6%), olefins (2–3%), oxygenates (5–8%) of the total detected compounds and others or unknown compounds. The premium gasoline showed higher concentrations of oxygenates and aromatics than the normal gasoline. Aromatics contributed 88% in the headspace vapour composition of premium grade and accounted for 86.9% of normal gasoline. VOCs are the primary precursors of ozone and secondary organic aerosols in ambient air; hence the environmental impacts like the ozone forming potential (OFP) and secondary organic aerosol formation potential (SOAP) of the target compounds were also determined in the study. The aromatics and paraffins showed the highest OFP and SOAP compared to the naphthenes and oxygenates. These results will aid in identifying the compounds that can be expected from fugitive emissions, define sources for receptor modeling, and determine the health and environmental risks associated with evaporative emissions.

This research examined the composition of PM_2.5, focusing on elemental carbon (EC), and organic carbon (OC), in six distinct indoor microenvironments (IMEs) and their associated outdoor locations (ODs). Four of the IMEs were located within the academic campus, Indian Institute of Technology Bombay (IITB), while two were situated within 500 m of IITB. Total carbon (TC = OC + EC) constituted 24.49–45.28% of indoor PM_2.5 and 22.87–38.64% of outdoor PM_2.5. Generally, the campus IMEs exhibited lower average PM concentrations compared to outdoor levels, with the dining room (IME4) being an exception. Indoor secondary organic carbon (ISOC) exceeded outdoor secondary organic carbon (OSOC) in all IMEs, apart from the library (IME3). All EC originated from outdoor sources in two campus-based IMEs—the hostel room (IME1) and the laboratory (IME2). IME4 and IME5 had over 30% of EC generated from indoor sources. OC2 and OC3 comprised over 70% of OC in IME4 and IME5. The study used the indoor-to-outdoor ratio of SOC/OC (I/OS_OC/OC) as an indicator for the favorability of chemical transformation inside an indoor microenvironment. The Total Respiratory Deposition Dose (TRDD), calculated using International Commission on Radiological Protection(ICRP) respiratory model, of EC was higher (> 0.030 µg/min) in indoor microenvironments with indoor sources present. The residential microenvironments with tiny volumes showed maximum favourability of the OC transformation to SOC. The study quantified health effects by calculating the number of passively smoked cigarettes (PSC). Number of PSC was > 2 for lung cancer and cardiovascular mortality in most of the studied locations.

Acryloyl peroxynitrate (APAN; molecular formula H₂C = CHC(O)O₂NO₂) is a trace gas found in the troposphere in elevated concentration in biomass burning plumes and downwind from petrochemical plants. Owing to the reactivity of the unsaturated side chain, its synthesis poses a challenge to laboratory studies and the calibration of field instruments alike. Here, the generation of APAN from photolysis at 285 nm of acrolein in air in the presence of NO_x (= NO + NO₂) is described. Formation of APAN is primarily initiated by the abstraction of the aldehydic hydrogen by the hydroxyl radical (OH). The output of APAN was increased by the addition of acetone, which acts as a source of OH radicals. Photochemically generated APAN was used to measure its room temperature Henry’s law solubility ((:{H}_{text{S}}^{cp})) and liquid phase loss rate (k_l) constants in deionized water using a jacketed bubble column apparatus. The measured (:{H}_{text{S}}^{cp}) value for APAN was (2.67 ± 0.10) M atm^− 1, where the error is at the 1σ level, and was on par with propionyl peroxynitrate (PPN). The k_l value of APAN in deionized water was determined to be (2.7 ± 0.4)×10^− 4 s^− 1, which is of similar magnitude as other PAN-type compounds.

This study investigates the impact of weather conditions specifically relative humidity (RH), temperature, wind speed (WS), and wind direction (WD) on air quality in Delhi during the Diwali festival. It analyzes PM_2.5 concentrations over an eight-year period during Diwali festival (2017–2024) at three key monitoring stations: IHBAS, DMS, and NSUT. The analysis reveals significant increases in PM_2.5 levels before, during, and after Diwali, with peak concentrations occurring during the festival due to firecracker usage. Meteorological factors, particularly RH, temperature, and WS, were found to significantly influence pollution spikes, with a strong correlation between these variables and Diwali-related air quality changes. In particular, the highest pollution levels were recorded during the night and early morning hours of Diwali, for exceeding the standard 24-hour limit of 60 µg/m³. The study also evaluates the accuracy of predictive models for air quality during Diwali, confirming that weather conditions, along with human activities, play a key role in forecasting pollution levels. The findings highlight the importance of incorporating environmental factors such as WS and WD along with Temp & RH and event based variable into predictive models for air quality and urban planning, especially during festive periods in Delhi. The results underscore the growing challenge of air pollution in the region and suggest that improving prediction models could help mitigate the adverse effects of seasonal air pollution, benefiting public health and environmental policies.

Heavy metals (HMs) in PM_2.5 have been extensively studied for their toxicity and carcinogenic risk. In this study, the toxicity and spatial health risks of PM_2.5-HMs from on-road vehicles were investigated in the Xiamen-Zhangzhou-Quanzhou (XZQ) metropolitan area in southeast China in 2021. The results show that the emissions of PM_2.5 and PM_2.5-HMs were 3219.54 and 89.48 t, with non-exhaust emissions contributing 62.1% and 87.6%, respectively. However, there were differences in the contribution of different sources to different HMs. The spatial distribution of PM_2.5 was characterized by high levels in the urban centers with high traffic flow and population. The daily PM_2.5 concentration could reach up to 6.85 μg/m³ in the area with heavy traffic. Wind speed and direction had a significant effect on the daily PM_2.5 concentration, while hourly concentrations were more influenced by variations in vehicle activity. The annual average concentration of Cr(VI) (0.15 ng/m³, estimated as 12% of total Cr) in the hotspot grid was six times the limit (0.025 ng/m³) of China’s air quality standard. Other toxic metals such as As, Cd and Pb were well below their guidelines. The health risk assessment showed that there was no threat of non-carcinogenic risks, but the carcinogenic risks in some urban centers exceeded the safety level of 10^–6. More than 90% of the carcinogenic risk came from Cr(VI), which mainly came from brake wear (55.7%) and diesel exhaust (32.5%). This study provides a scientific basis for the development of more effective pollution control strategies and public health policies.