Journal of Atmospheric Chemistry最新文献

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.

This study analyzed the impact of air-mass transport via the Yellow Sea (YS) pathway on PM_2.5 concentrations and chemical composition in Seoul from 2016 to 2021, focusing on heavy metals while also considering inorganic and organic species. Using backward trajectories from the HYSPLIT model, the analysis showed that YS-pathway cases consistently showed higher concentrations PM_2.5 and most components compared to non-YS-pathway cases, indicating that the influence of transboundary air pollutants transported via the Yellow Sea persisted. This difference was also influenced by local meteorological conditions, such as lower planetary boundary layer heights and weaker wind speeds during YS-pathway cases in winter, which are unfavorable for pollutant dispersion. Vanadium (V) and nickel (Ni), markers of heavy oil combustion, showed similar trends, with significant declines in 2020 and 2021, likely due to the IMO 2020 regulation and reduced shipping activity during the COVID-19 pandemic. In contrast, arsenic (As) and selenium (Se), markers of coal combustion, showed different trends, suggesting variations in their emission sources. Elevated As levels observed in late 2020 were attributed to emissions from coal-fired power plants in North Korea and Liaoning Province, China. Meanwhile, lead (Pb) and As exhibited no significant differences between YS-pathway and non-YS-pathway cases, suggesting that their source distributions differ from those of other pollutants. These findings highlight the ongoing influence of transboundary air pollutants on air quality in Seoul and emphasize the need for international collaboration, sustained monitoring, and effective domestic and regional emissions controls.

Traffic activities and road dust are major contributors to the release of metals in ambient air which further cause serious health risks by entering the body. This study examined size-segregated PM concentration trends in rural site (Iradatnagar) Risk assessement and disease estimation was done by AirQ + and USEPA Methodology. PM_2.5-1.0 levels were 294.64 µg/m³ in summer and 78.81 µg/m³ was found in monsoon, while PM_1.0-0.5 measured 204.53 µg/m³ in summer and 66.42 µg/m³ in monsoon, respectively. Al, Ba, Ca, Fe, Mg, Mn, Pb, Ni, Cr, Cd, Cu, and Zn were analyzed. Total metal concentration was found to be 32.96 µg/m³ in summer and 12.27 µg/m³ in monsoon for PM_2.5−1.0, while for PM_1.0−0.5 it was found as 30.42 µg/m³ and 10.56 µg/m³ in summer and monsson respectively. According to the findings, the concentration of metals was higher in summer. Metal BI ranged from 5.12 to 6.46% (PM2.5-1.0) and 4.56–7.05% (PM1.0-0.5). HQ outcomes Cr(2.78, 9.59E-02), Ni(2.73, 6.85E-01), Al(1.43, 4.79E-01), and Mn(0.19, 1.92E-01) were observed for PM_2.5−1.0 in the summer and monsoon seasons respectively. HQ outcomes Cr(3.16, 9.59E-02), Ni(0.68, 6.85E-01), Al(1.55, 5.56E-01), and Mn(0.76, 1.92E-01) were identified for PM_1.0−0.5 in summer, and monsoon seasons. HQ was observed higher for PM_1.0−0.5 (1.95) size fractions compared to PM_2.5−1.0 (1.30). ELCR value for Cr(VI) was found higher for adult in comparison with child whereas the trend followed as as Cr(VI) (0.0007), (0.0002) > Pb (3.52E-06)(1.05E-06) > Ni (1.31E-06)(3.94E-07). Adult values were found to be greater (0.0002) than child values (7.10E-05). The Cancerous risk mean value found two times higher than the permissible limit (1 × 10^− 6).

This study investigates the mass concentrations, morphological characteristics, elemental composition and source apportionment of PM2.5 and PM10 aerosols across different seasons collected in a mountain valley of the central Himalayan region of Uttarakhand, India. The average PM10 concentration was found to be 88.74 ± 34.12 µg m⁻³, generally below the NAAQS 24-h standard, while the mean PM2.5 concentration was found to be 67.72 ± 37.00 µg m⁻³, exceeding the NAAQS standard. Elevated PM10 levels during pre-monsoon periods were linked to windblown dust from neighbouring regions and thermodynamic conditions within the planetary boundary layer, while high PM2.5 levels were attributed to temperature inversions and stable atmospheric conditions. The study identified three major particle groups—biogenic, geogenic, and anthropogenic—using SEM–EDX analysis highlighting the significant impact of both natural and anthropogenic sources. Biogenic aerosols were prevalent in the samples. Variations in the composition of the elements are noted, with C and Si being the most predominant. A strong correlation was found between carbon and oxygen (r = 0.926) using Pearson correlation matrix. NOAA HYSPLIT-4 model was used for air mass back trajectory analysis, which suggests that the receptor site station received air mass from both local sources and long-range transport.

Ozone (O₃) in ambient air acts as a greenhouse gas and has harmful effects on human health and vegetation. Short-term exposure to elevated surface O₃ is linked to increased risks of respiratory and cardiovascular mortality. The emission of volatile organic compounds (VOCs) and nitrogen oxides (NO_x) into the atmosphere can trigger chemical reactions influenced by solar radiation (SR), resulting in O₃ formation in the troposphere. This study focuses on a few locations within Delhi and Mumbai using publicly available data. O₃ concentrations peak in the afternoon and decrease subsequently. During winter, NO_x concentrations were higher, while O₃ concentrations were lower, possibly due to reduced solar radiation and altered atmospheric VOC-NO_x regimes. The HCHO/NO₂ ratios in both Delhi and Mumbai are less than 1, indicating VOC-limited conditions. The secondary fraction (SA) of PM_2.5 at select locations was estimated using the Approximate Envelope Method (AEM). SA values derived from AEM exhibited diurnal trends consistent with field studies and established knowledge. This analysis demonstrated that SA can constitute up to 85% of total PM_2.5, highlighting its significant contribution to overall particulate matter levels. An evaluation of the AVOC-NOx-O₃-SA relationship revealed that elevated O₃ concentrations predominantly occur at higher AVOC/NOx ratios, often leading to increased SA levels to some extent. To predict O₃, a multiple linear regression model was employed, incorporating various parameters. The model achieved a coefficient of correlation when compared to measured data of over 0.90, indicating its effectiveness in predicting O₃ levels. This research provides valuable insights into the dynamics of surface O₃ and its implications for urban secondary pollutants.

Though Dhaka is among the most air polluted cities, the origin and impact of respirable crystalline silica (RCS) are mostly unclear. This study examines the concentrations and sources of RCS and heavy metal in the ambient air of Dhaka city due to its health hazards. Samples were obtained from the industrial area, construction zone, hospital, and workshop over a period of three consecutive days. Each sample was collected using a polytetrafluoroethylene filter for a duration of 24 h. The quantification of RCS and heavy metal concentration was performed utilizing UV-vis and ICP-MS techniques, while SEM-EDX was employed to examine the morphology of total suspended particulate matter (TSP). The construction zone had the highest concentration of RCS, measuring 2.55 µgm^− 3 suggesting the likely source of the RCS. Additionally, this research revealed that among all locations, at least five individuals per 10,000 will be susceptible to cancer as a result of RCS. Construction zone exhibited a low level of heavy metal concentration, whereas industrial area contained the highest levels. The industrial area was found to contain the highest concentrations of Pb and Hg among the four heavy metals, while the workshop exhibited the highest concentrations of Cr and As. SEM analysis revealed a lot of soot particles that had chromium in them. Aluminum was found in the silica particle that reveal the source of it with more accuracy. This aerosol morphology investigation will assist stakeholders understand pollution source and type.