Asian Journal of Atmospheric Environment最新文献

Volcanic and geothermal activities are one of the major emission sources of mercury (Hg), emitting 500 tons y^− 1 into the atmosphere, and it is known that there are three main forms of Hg released to the atmosphere from these activities: gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particle-bound mercury (PBM). In this study, the concentrations of GEM, GOM and PBM_2.5 (PBM in particles less than 2.5 μm) were continuously observed for 2 years at Sensuikyo Station, located 2.5 km northeast from Nakadake No. 1 Crater of Mt. Aso. The observed mean concentrations of GEM, GOM, and PBM_2.5 in the entire period were 1.64, 0.021 and 0.021 ng m^− 3, while maximum concentrations were 9.04, 2.45 and 3.20 ng m^− 3, respectively. The concentrations increased significantly when the volcanic activity was high and when the wind blew from the crater. Under high volcanic activity, the mean concentrations of GEM, GOM and PBM_2.5 were 1.3, 4.1, and 15.3 times higher than those during calm conditions. Changes in GOM and PBM_2.5 concentrations between active and calm conditions were significantly higher than those of GEM. The amplitude of volcanic tremors is usually used as a reference indicator of the volcanic activity. GOM and PBM_2.5 concentrations became higher before the volcanic tremor amplitude increased. However, the reliability of atmospheric GOM measurements in volcanic regions with high levels of acidic gases is still debatable. Therefore, PBM_2.5 concentrations can be used as one of the indicators to assess the activity of Mount Aso volcano.

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In this study, to assess the long-term air quality status in South Korea, we analyzed the concentration and attainment rate of air quality standards for 8 pollutants such as SO₂, NO₂, CO, O₃, PM₁₀, PM₂.₅, Pb, and benzene. In 2023, the average concentrations were as follows: PM₁₀ 37 µg/m³, PM₂.₅ 19 µg/m³, SO₂ 0.0025 ppm, NO₂ 0.0135 ppm, CO 0.39 ppm, O₃ 0.0327 ppm, Pb 0.01979 µg/m³, and benzene 0.64 µg/m³. Due to ongoing strict emission control policies, PM₂.₅ and NO₂ levels have decreased by approximately 27% and 43%, respectively, compared to 2015. Other pollutants, including SO₂, CO, PM₁₀, Pb, and benzene, also showed significant reductions, ranging from 36% to 74%, over the analyzed period. However, O₃ levels have shown a 73% increase since 1998. Primary pollutants have generally decreased in concentration with higher attainment rate for air quality standards, whereas PM₂.₅, a secondary pollutant, still exhibits a low attainment rate of less than 20% in 2023 despite concentration reductions. Likewise, low attainment rate coupled with rising O₃ levels indicate a need to focus on secondary pollutants in future air quality management policies. This study provides long-term observational data on air pollutants in South Korea, which can aid in understanding air quality across East Asia and help to make a direction ongoing air quality improvement policy.

Air pollution is the most significant environmental health risk, and the chemical composition of PM_2.5 has the greatest impact on its effects on human health. While PM_2.5 pollution has been widely studied, little attention has been given to the role of landfill fires in shaping PM_2.5 composition and dispersion in medium-sized cities with complex topographies. This study integrates the physical and chemical characterization of PM_2.5 (potassium, chlorine, and irregular morphology) with AERMOD dispersion modeling to assess exposure during a landfill fire in Guanajuato, Mexico. The maximum monthly average concentration was recorded in May at 22.4 µg m⁻³, while the 24-h average exceeded the allowable limit of 33 µg m⁻³ during the days of the landfill fire, reaching 50 µg m⁻³. The annual average concentration (13.4 µg m⁻³) also exceeded the 10 µg m⁻³ guideline. AERMOD simulations reproduced observed patterns, confirming northeastward dispersion toward the city hillside. Based on the 12-h moving average during the fire (45 µg m⁻³), residents were exposed to poor air quality and elevated risks of respiratory and cardiovascular diseases, stroke, and lung cancer. These results provide novel evidence of the contribution of landfill fires to urban PM_2.5 pollution and associated health risks, offering valuable insights for air quality management and public health protection in cities with similar environmental conditions.

To better understand the actual status of volatile organic compound (VOC) emissions from the livestock industry in Japan, air samples were collected near the exhaust vents of a windowless commercial layer hen facility located in the northern Kanto region. Environmental parameters including temperature, relative humidity, and wind speed at the ventilation outlets were also recorded. The average VOC concentration inside the shed ranged from 151 to 448 μg m⁻³, consistent with those observed in educational hen sheds. Volatile fatty acids (VFAs) were the most abundant VOCs across all months, followed by ketones and aldehydes, together accounting for 72–91% of total VOCs. Regarding atmospheric impacts, VFAs contributed most to hydroxyl radical reactivity (OHR), while aldehydes dominated ozone formation potential (OFP). VOC emission rates (ERs) ranged from 271 to 1240 μg h⁻¹ kg⁻¹, with the highest value recorded in June, and were positively correlated with in-shed temperature. The estimated annual VOC emissions from commercial layer hen facilities across Japan totaled approximately 455 tons, representing ~0.1% of the country’s anthropogenic VOC emissions.

The study on solar ultraviolet radiation (UVR) is essential for understanding the solar status of any location, which enables the determination of the level of exposure to solar UV radiation and the necessary precautions to be taken at that location. The measurement of solar UV radiation and its validation are increasingly prevalent worldwide, using various ground-based observations and satellite estimates. This paper compares the Ozone Monitoring Instrument (OMI)/Aura satellite solar ultraviolet index (UVI) with the ground-based UVI measurements at Biratnagar, Pokhara, Kathmandu, and Lukla in Nepal using data from 2009 to 2012. Trend analysis of UVI using moving averages, a box plot of overpass UVI and Total Ozone Column (TOC) to analyze their trends, and a scatter plot for comparison of OMI overpass UVI with ground-based UVI. Statistical tools were used to compare the datasets for UVI in all-sky conditions. The results show that satellite estimates tended to overestimate ground-based UVI levels, with a mean bias, relative bias, MAPE, RMSE, correlation coefficient, and standard deviation of error corresponding to 0.92, 1.9, 28.44, 1.6, 0.69, and 1.44 for UVI, respectively. The result also shows that the altitude effect is found to be (6.5-8.8) %/km approximately.

N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine quinone (6PPD-quinone) is an oxidation product of the tire antioxidant 6PPD and has recently emerged as a toxic environmental contaminant. Although the transformation of 6PPD to 6PPD-quinone through ozone has been documented, the influence of other atmospheric constituents as catalysts remains inadequately characterized. This study assessed whether specific airborne elements promote the conversion of 6PPD to 6PPD-quinone. From 7 to 26 June 2024, total suspended particles were sampled at the National Institute of Environmental Research in Incheon, Republic of Korea. The elemental composition of collected samples was determined using energy-dispersive X-ray fluorescence, while 6PPD-quinone levels were measured by liquid chromatography–tandem mass spectrometry. Particle number and volume concentrations were recorded in parallel with a scanning mobility particle sizer and an optical particle sizer, along with real-time detection of black carbon, nitrogen dioxide, and ozone. Mean daytime 6PPD-quinone concentrations were measured at 0.12 ± 0.08 ng m^− 3, displaying significant temporal variability (0.001–0.519 ng m^− 3). Multivariate regression analysis identified bromine and vanadium as principal predictors of 6PPD-quinone abundance. Notably, strong correlations with particle characteristics indicated that these elements may act not only as markers of emissions but also as catalysts facilitating atmospheric transformation of 6PPD. This study offers the first mechanistic insight in Korea into the contribution of traffic-associated elements to 6PPD-quinone formation, which has important implications for urban air quality management and the assessment of ecological risks.

This study examines variations in PM_2.5 mass, chemical composition, and oxidative potential (OP) at Gwanghwamun Square, Seoul, using intensive 3-h integrated sampling campaigns performed in September 2020 and 2022. The mean PM_2.5 concentrations declined significantly from 20.66 µg/m³ in 2020 to 12.04 µg/m³ in 2022, indicating a 42% reduction in overall particle mass. Despite this progress, the mass-normalized oxidative potential (DTTm) remained statistically unchanged (0.04 ± 0.04 vs. 0.03 ± 0.05 µM/µg, showing that particle toxicity per unit mass did not decrease. However, organic aerosol components exhibited marked increases in 2022. Organic carbon (OC) and water-soluble organic carbon (WSOC) increased by 22% and 82%, respectively, and primary organic carbon (POC) experienced more than a twofold rise. Levoglucosan (LEVO) concentrations grew by 37%, especially during nighttime periods, and the levoglucosan-to-POC ratio (LEVO/POC) surpassed 35 × 10^− 3 µg/µg at night, providing clear evidence of intensified biomass burning contributions. Annual flammable waste wood generation increased substantially in 2022, further supporting the conclusion that nighttime waste wood combustion contributed to higher organic aerosol levels and persistent OP values. These findings emphasize that reducing PM_2.5 mass alone is inadequate; targeted interventions to control nighttime biomass burning are essential for lowering health-relevant aerosol toxicity in urban Seoul.

Polycyclic aromatic sulfur heterocycles (PASHs) sulfur-containing analogues of polycyclic aromatic hydrocarbons (PAHs) are emerging atmospheric pollutants of concern due to their potential toxicity and environmental persistence. This study presents the first comparative analysis of PASHs in PM_2.5 between two representative East Asian cities: Xi’an, China, and Yokohama, Japan. Ambient PM_2.5 samples were collected from July 2022 to July 2023, and four PASHs compounds were quantified using gas chromatography tandem mass spectrometry (GC–MS/MS). Concentrations, seasonal variations, and emission sources were systematically analyzed. The results showed that the annual mean PASHs concentration in Xi’an (156.6 pg/mg) was significantly higher than that in Yokohama (102.6 pg/mg). Source apportionment using the Positive Matrix Factorization (PMF) model identified four major pollution sources in each city, revealing notable differences in source composition between the two countries. This study advances the understanding of the atmospheric behavior and origins of PASHs in East Asian urban environments and highlights cross-regional differences in their pollution profiles.

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Atmospheric concentrations of peroxides (hydrogen peroxide (H₂O₂) and methyl hydroperoxide (MHP)), formaldehyde (HCHO), ozone (O₃), and sulfur dioxide (SO₂) were measured using a helicopter over Imizu City, Toyama Prefecture, central Japan in early summer (May and June) from 2022 to 2024. The impact of transboundary air pollution was relatively small during the observation days. H₂O₂ concentrations were higher in the high-altitude atmosphere than on the ground and were sufficiently high relative to SO₂, similar to the H₂O₂ concentrations previously measured in mid-summer (August), suggesting that the potential for sulfur dioxide oxidation is high over central Japan during warm seasons. HCHO concentrations in the high-altitude atmosphere were high due to the influence of air pollution from domestic urban areas. The measurement results in this study were compared with the results of a series of helicopter observations previously conducted over Toyama Prefecture, and the characteristics of the oxidizing capacity in the atmosphere over central Japan are discussed.

Graphical Abstract