Search Results (135)

Atmospheric aerosols are recognized as a major air pollutant with significant impacts on human health, air quality, and climate. Yet, the chemical composition and seasonal variability of aerosols remain underexplored in several Western Mediterranean regions. This study presents a year-long investigation of PM_2.5 and PM₁₀ in Tetouan, Northern Morocco, where both local emissions and regional transport influence air quality. PM_2.5 and PM₁₀ samples were collected and analysed for total mass and comprehensive chemical characterization, including organic carbon (OC), elemental carbon (EC), water-soluble ions (WSIs), and sugar tracers (levoglucosan, arabitol, and glucose). Concentration-weighted trajectory (CWT) modelling and air mass back-trajectory analyses were used to assess potential source regions and transport pathways. PM_2.5 concentrations ranged from 4.2 to 41.8 µg m⁻³ (annual mean: 18.0 ± 6.4 µg m⁻³), while PM₁₀ ranged from 11.9 to 66.3 µg m⁻³ (annual mean: 30.8 ± 9.7 µg m⁻³), with peaks in winter and minima in spring. The PM_2.5-to-PM₁₀ ratio averaged 0.59, indicating a substantial accumulation of particle mass within the fine fraction, especially during the cold season. Carbonaceous aerosols dominated the fine fraction, with total carbonaceous aerosol (TCA) contributing ~52% to PM_2.5 and ~34% to PM₁₀. Secondary organic carbon (SOC) accounted for up to 90% of OC in PM_2.5, reaching 7.3 ± 3.4 µg m⁻³ in winter. WSIs comprised ~39% of PM_2.5 mass, with sulfate, nitrate, and ammonium as major components, peaking in summer. Sugar tracers exhibited coarse-mode dominance, reflecting biomass burning and biogenic activity. Concentration-weighted trajectory and back-trajectory analyses identified the Mediterranean Basin and Iberian Peninsula as dominant source regions, in addition to local urban emissions. Overall, this study attempts to fill a critical knowledge gap in Southwestern Mediterranean aerosol research by providing a comprehensive characterization of PM_2.5 and PM₁₀ chemical composition and their seasonal dynamics in Tetouan. It further offers new insights into how a combination of local emissions and regional transport shapes the aerosol composition in this North African urban environment. Full article

Carbonaceous aerosols exert significant impacts on human health and climate systems. This study investigates the seasonal variations of carbonaceous components in fine particulate matter (PM_2.5) in Qinhuangdao, a coastal city in northern China, throughout 2023. The mass concentrations of organic carbon (OC) and elemental carbon (EC) averaged 9.44 ± 4.57 μg m⁻³ and 0.84 ± 0.33 μg m⁻³, contributing 26.49 ± 8.74% and 2.81 ± 1.56% to total PM_2.5, respectively. OC exhibited a distinct seasonal trend: winter (12.02 μg m⁻³) > spring (11.96 μg m⁻³) > autumn (8.15 μg m⁻³) > summer (5.71 μg m⁻³), whereas EC followed winter (1.31 μg m⁻³) > autumn (0.73 μg m⁻³) > spring (0.70 μg m⁻³) > summer (0.63 μg m⁻³). Both OC and EC levels were elevated at night compared to daytime. Secondary organic carbon (SOC), estimated via the EC-tractor method, constituted 37.94 ± 14.26% of total OC. A positive correlation between SOC/OC ratios and PM_2.5 concentrations suggests that SOC formation critically influences haze events. In autumn and winter, SOC formation was higher at night, likely driven by aqueous-phase reactions, whereas in summer SOC formation was more pronounced during the day, likely due to enhanced photochemical reactions. Source apportionment analysis revealed that gasoline and diesel vehicles were major contributors to carbonaceous aerosols, accounting for 27.35–29.06% and 14.97–31.83%, respectively. Coal combustion contributed less (10.51–21.55%), potentially due to strict regulations prohibiting raw coal use for domestic heating in surrounding regions. Additionally, fugitive dust was found to have a high contribution to carbonaceous aerosols during spring and summer. Full article

The occurrence of haze pollution significantly deteriorates air quality and threatens human health, yet persistent knowledge gaps in real-time source apportionment of fine particulate matter (PM_2.5) hinder sustained improvements in atmospheric pollution conditions. Thus, this study employed single-particle aerosol mass spectrometry (SPAMS) to investigate PM_2.5 sources and dynamics during winter haze episodes in Yinchuan, Northwest China. Results showed that the average PM_2.5 concentration was 57 μg·m⁻³, peaking at 218 μg·m⁻³. PM_2.5 was dominated by organic carbon (OC, 17.3%), mixed carbonaceous particles (ECOC, 17.0%), and elemental carbon (EC, 14.3%). The primary sources were coal combustion (26.4%), fugitive dust (25.8%), and vehicle emissions (19.1%). Residential coal burning dominated coal emissions (80.9%), highlighting inefficient decentralized heating. Source contributions showed distinct diurnal patterns: coal combustion peaked nocturnally (29.3% at 09:00) due to heating and inversions, fugitive dust rose at night (28.6% at 19:00) from construction and low winds, and vehicle emissions aligned with traffic (17.5% at 07:00). Haze episodes were driven by synergistic increases in local coal (+4.0%), dust (+2.7%), and vehicle (+2.1%) emissions, compounded by regional transport (10.1–36.7%) of aged particles from northwestern zones. Fugitive dust correlated with sulfur dioxide (SO₂) and ozone (O₃) (p < 0.01), suggesting roles as carriers and reactive interfaces. Findings confirm local emission dominance with spatiotemporal heterogeneity and regional transport influence. SPAMS effectively resolved short-term pollution dynamics, providing critical insights for targeted air quality management in arid regions. Full article

Biomass burning processes affect many semi-rural areas in the Mediterranean, but there is a lack of long-term datasets focusing on their classification, obtained by monitoring carbonaceous particle concentrations and optical properties variations. To address this issue, a campaign to measure equivalent black carbon (eBC) and particle number size distributions (0.3–10 μm) was carried out from August 2019 to November 2020 at a coastal semi-rural site in the Basilicata region of Southern Italy. Long-term datasets were useful for aerosol characterization, helping to clearly identify traffic as a constant eBC source. For a shorter period, PM_2.5 mass concentrations were also measured, allowing the estimation of elemental and organic carbon (EC and OC), and chemical and SEM (scanning electron microscope) analysis of aerosols collected on filters. This multi-instrumental approach enabled the discrimination among different biomass burning (BB) processes, and the analysis of three case studies related to domestic heating, regional smoke plume transport, and a local smoldering process. The AAE (Ångström absorption exponent) daily pattern was characterized as having a peak late in the morning and mean hourly values that were always higher than 1.3. Full article

Medellín, a densely populated city in the Colombian Andes, faces significant health and environmental risks due to poor air quality. This is linked to the atmospheric dynamics of the valley in which it is located (Aburrá Valley). The region is characterized by a narrow valley and one of the most polluted areas in South America. This is a comparative study of the chemical composition of PM_2.5 (particles with diameter less than 2.5 µm) in Medellín between two periods (2014–2015 and 2018–2019) in which temporal trends and emission sources were evaluated. PM_2.5 samples were collected from urban, suburban, and rural stations following standardized protocols and compositional analyses of metals (ICP-MS), ions (ion chromatography), and carbonaceous species (organic carbon (OC) and elemental carbon (EC) by thermo-optical methods) were performed. The results show a reduction in average PM_2.5 concentrations for the two periods (from 26.74 µg/m³ to 20.10 µg/m³ in urban areas), although levels are still above WHO guidelines. Urban stations showed higher PM_2.5 levels, with predominance of carbonaceous aerosols (Total Carbon—TC = OC + EC = 35–50% of PM_2.5 mass) and secondary ions (sulfate > nitrate, 13–14% of PM_2.5 mass). Rural areas showed lower PM_2.5 concentrations but elevated OC/EC ratios, suggesting the influence of biomass burning as a major emission source. Metals were found to occupy fractions of less than 10% of the PM_2.5 mass; however, they included important toxic species associated with respiratory and cardiovascular risks. This study highlights progress in reducing PM_2.5 levels in the region, which has been impacted by local policies but emphasizes current and future challenges related mainly to secondary aerosol formation and carbonaceous aerosol emissions. Full article

This study examines the seasonality of Black Carbon (BC) and Brown Carbon (BrC) spectral absorption characteristics at a continental background site (Kozani) in southern Balkans (NW Greece). It aims to assess the seasonality and impact of different sources on light absorption properties, BC concentrations, and the fraction of BrC absorption. Moderate-to-low BC concentrations were observed, ranging from 0.05 µg m⁻³ to 2.44 µg m⁻³ on an hourly basis (annual mean: 0.44 ± 0.27 µg m⁻³; median: 0.39 µg m⁻³) with higher levels during winter (0.53 ± 0.33), reflecting enhanced emissions from residential wood burning (RWB) for heating purposes. Atmospheric conditions are mostly clean during spring (MAM) (BC: 0.34 µg m⁻³), associated with increased rainfall. BC components associated with fossil fuel combustion (BC_ff) and biomass burning (BC_bb), maximize in summer (0.36 µg m⁻³) and winter (0.28 µg m⁻³), respectively, while the absorption Ångstrôm exponent (AAE_370–880) values ranged from 1.09 to 1.93 on daily basis. The annual mean total absorption coefficient (b_abs,520) inferred by aethalometer (AE33) was 4.09 ± 2.65 Mm⁻¹ (median: 3.51 Mm⁻¹), peaking in winter (5.30 ± 3.35 Mm⁻¹). Furthermore, the contribution of BrC absorption at 370 nm, was also high in winter (36.7%), and lower during the rest of the year (17.3–29.8%). The measuring station is located at a rural background site 4 km outside Kozani City and is not directly affected by traffic and urban heating emissions. Therefore, the regional background atmosphere is composed of a significant fraction of carbonaceous aerosols from RWB in nearby villages, a characteristic feature of the Balkan’s rural environment. Emissions from the lignin-fired power plants, still operating in the region, have decreased during the last years and moderately affect the atmospheric conditions. Full article

Aerosols significantly impact the brightness temperature (BT) in thermal infrared (IR) channels, and ignoring their effects can lead to relatively large observation-minus-background (OMB) bias in radiance calculations. The accuracy of aerosol datasets is essential for BT simulations and bias reduction. This study incorporated aerosol reanalysis datasets from the Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) and Copernicus Atmosphere Monitoring Service (CAMS) into the Advanced Radiative Transfer Modeling System (ARMS) to compare their impacts on BT simulations from the Geostationary Interferometric Infrared Sounder (GIIRS) and their effectiveness in reducing OMB biases. The results showed that, for a sandstorm event on 10 April 2023, incorporating total aerosol data from the MERRA-2 improved the BT simulations by 0.56 K on average, surpassing CAMS’s 0.11 K improvement. Dust aerosols notably impacted the BT, with the MERRA-2 showing a 0.17 K improvement versus CAMS’s 0.06 K due to variations in the peak aerosol level, thickness, and column mass density. Improvements for sea salt and carbonaceous aerosols were concentrated in the South China Sea and Bay of Bengal, where the MERRA-2 outperformed CAMS. For sulfate aerosols, the MERRA-2 excelled in the Bohai Sea and southern Bay of Bengal, while CAMS was better in the northern Bay of Bengal. These findings provide guidance for aerosol assimilation and retrieval, emphasizing the importance of quality control and bias correction in data assimilation systems. Full article

A study of carbonaceous species, polycyclic aromatic hydrocarbons (PAHs), and nitro-PAHs associated with PM_2.5 was conducted to assess their carcinogenic potential and associated health risks in the two main cities of the State of Morelos: Cuernavaca and Cuautla. The annual median concentrations in Cuernavaca of organic carbon (OC) and elemental carbon (EC) were 6.2 µg m⁻³ and 0.6 µg m⁻³, respectively, whereas in Cuautla, OC concentrations averaged 4.8 µg m⁻³ and EC 0.6 µg m⁻³. OC/EC ratios, total carbonaceous aerosols (TCA), primary (POC) and secondary organic carbon (SOC), as well as elemental carbon reactive (ECR) were estimated, also showing prevalence of primary emissions such as biomass burning. The seventeen PAHs recommended by the EPA and twelve nitro-PAHs were measured using gas chromatography–mass spectrometry. The annual median sum of PAHs was 9.7 ng m⁻³ in Cuernavaca and 11.2 ng m⁻³ in Cuautla, where carcinogenic high-molecular-weight compounds were the most dominant; the annual median sums of nitro-PAHs were 287 pg m⁻³ and 432 pg m⁻³, respectively. Diagnostic ratios were applied to identify potential sources of PAH emissions, suggesting that fuel combustion is the major contributor in both sites, followed by coal biomass burning and agricultural activities. The annual carcinogenic potential as benzo(a)pyrene equivalent was 2.2 ng m⁻³ for both sites. The lifetime excess cancer risk from PAH inhalation was estimated to range from 1.8 × 10⁻⁴ to 2 × 10⁻⁴ in Cuernavaca and from 1.5 × 10⁻⁴ to 2.2 × 10⁻⁴ in Cuautla, similar to values observed in other urban regions globally. Full article

Air pollution can induce diseases and increase the risks of death, and it also has close links with climate change. Carbonaceous matter is an important component of aerosols, but studies quantifying the source apportionment of carbonaceous compositions in different-sized aerosols from a stable carbon isotopic perspective remain scarce. In this study, fine (particulate size < 2.5 μm) and coarse (particulate size 2.5~10 μm) particles were collected from December 2021 to February 2022 (winter) and from June to August 2022 (summer) in the tropical city of Haikou; the concentrations of water-soluble inorganic ions (WSIIs) and total carbonaceous matter (TC) and the stable carbon isotope of TC (δ¹³C-TC) values in both fine and coarse particles were analyzed. Higher concentrations of TC, SO₄²⁻, NO₃⁻, and NH₄⁺ but lower δ¹³C-TC values in fine particles than those in coarse particles in both winter and summer indicated that combustion-related emissions dominate fine particulate TC sources. The δ¹³C-TC values coupled with the stable isotope mixing model in R (SIAR) results showed that combustion-related emissions contributed 77.5% and 76.6% to the TC of fine particles in winter and summer, respectively. Additionally, the lowest δ¹³C-TC values were observed in summertime fine particles; plant physiological activity was identified as an important source of fine particulate TC in summer and contributed 12.4% to fine particulate TC. For coarse particles, higher δ¹³C-TC values and Ca²⁺ and Na⁺ concentrations but lower TC concentrations implied significant contributions from natural emissions (29.2% in winter and 44.3% in summer) to coarse particulate TC. This study underscores that instead of fossil fuels and biomass, clean energy can decrease 45–78% of aerosol TC at Haikou. In addition, our results also provide a dataset for making environmental policy and optimizing the energy structure, which further favors the sustainable development of air quality. Full article

Many cities in China are facing the dual challenge of PM_2.5 and PM₁₀ pollution. There is an urgent need to develop a cost-effective method that can apportion both with high-time resolution. A novel and practical apportionment method is presented in this study. It combines the measurement of particle mass size distribution (PMSD) with an optical particle counter (OPC) and the algorithm of normalized non-negative matrix factorization (N-NMF). Applied in the city center of Baoding, Hebei, this method separates four distinct pollution factors. Their sizes (ordered from the smallest to largest) range from 0.16 μm to 0.6 μm, 0.16 μm to 1.0 μm, 0.5 μm to 17.0 μm, and 2.0 μm to 20.0 μm, respectively. They correspondingly contribute to PM_2.5 (PM₁₀) with portions of 26% (17%), 37% (26%), 33% (41%), and 4% (16%), respectively, on average. The smaller three factors are identified as combustion, secondary, and industrial aerosols because of their high correlation with carbonaceous aerosols, nitrate aerosols, and trace elements of Fe/Mn/Ca in PM_2.5, respectively. The largest-sized factor is linked to dust aerosols. The primary origin regions, oxidation degrees, and formation mechanisms of each source are further discussed. This provides a scientific basis for the comprehensive management of PM_2.5 and PM₁₀ pollution. Full article

To determine the link between hygroscopicity and the constituent chemical composition of real biomass-burning atmospheric particles, we collected and analyzed aerosols during wheat-straw (April–May), rice-straw (October–November), and no-burning periods (August–September) in 2008 and 2009 in Patiala, Punjab. A hygroscopicity tandem differential mobility analyzer (HTDMA) system was used to measure hygroscopicity at ~5 to ~95% relative humidity (RH) of aerosolized 100 nm particles generated from the water extracts of PM_0.4 burning and no-burning aerosol samples. The chemical analyses of the extracts show that organic carbon and water-soluble inorganic-ion concentrations are 2 to 3 times higher in crop-residue burning aerosol samples compared to no-burning aerosols, suggesting the substantial contribution of biomass burning to the carbonaceous aerosols at the sampling site. We observed that aerosolized 100 nm particles collected during the crop-residue burning period show higher and more variable hygroscopic growth factor (g(RH)) ranging from 1.21 to 1.68 at 85% RH, compared to no-burning samples (1.27 to 1.33). Interestingly, crop-residue burning particles also show considerable shrinkage in their size (i.e., g(RH) < 1) at lower RH (<50%) in the dehumidification mode. The increased level of major inorganic ions in biomass-burning period aerosols is a possible reason for higher g(RH) as well as the observed particle shrinkage. Overall, the measured g(RH), together with the correlation observed between aerosol water content and ionic-species volume fraction, and the study of the abundance of individual constituent ionic species suggests that inorganic salts and their proportion in aerosol particles primarily governed the aerosol hygroscopicity. Full article

This study analyses the trends of total aerosol and the main aerosol species over nine capitals in the Baltic Sea basin from 1989 to 2019 based on the Modern-Era Retrospective Analysis for Research and Applications, Version 2 Reanalysis. Aerosol speciation includes mineral dust, sea salt, sulphate (SO₄), organic carbon (OC), and black carbon (BC). The mean total aerosol optical depth (AOD) values were the highest (up to 0.216) over the continental capitals (i.e., Warsaw, Berlin, and Vilnius). For each capital, the mean SO₄ AOD was the main aerosol species, with a trend specular to total AOD. Apart from Warsaw, the mean BC AOD was the aerosol species with the lowest level. The composition of aerosols changed with respect to the species of anthropogenic origins (i.e., SO₄, OC, and BC), with the percentage contribution to the total AOD decreasing for the SO₄ AOD and increasing for the BC AOD. Also, the OC AOD showed an increase in the percentage contribution to total AOD for Copenhagen, Oslo, Stockholm, and the continental capitals. Anthropogenic aerosols contributed up to 90.3% of the total AOD, with the highest values over the continental capitals. For each capital, the minimum in the percentage contribution of anthropogenic AOD was between 2007 and 2008, likely due to the global financial crisis. Anthropogenic AOD as a percentage of the total AOD decreased from 1989 to 2008. Both the total and the SO₄ AODs decreased over each capital. By contrast, the BC AOD increased over Stockholm, and both the OC and BC AODs increased over Berlin, Copenhagen, and Oslo. The decoupling of carbonaceous aerosols and the SO₄ AOD trends was likely due to concurrent factors such as biomass burning and low-sulphur fuel policies. From 2000 to 2019, the inverse relationships between gross domestic products and SO₄ AODs suggest a relative decoupling of economic growth from fossil fuels for Oslo, Stockholm, Tallinn, and Vilnius. Full article

The goals of the “dual carbon” program in China are to implement a series of air pollution policies to reduce the emission of carbon-bearing particulate matter (PM). Following improvements in the reduction in carbon emissions in Handan City, China, fine particulate matter (PM_2.5) was collected in the winters from 2016 to 2020 to characterize the concentrations and sources of carbonaceous components in PM_2.5. Trend analysis revealed that both organic carbon (OC) and elemental carbon (EC) concentrations significantly decreased. The proportion of total carbon aerosol (TCA) in PM_2.5 decreased by 47.0%, highlighting the effective reduction in carbon emissions. Secondary organic carbon (SOC) concentrations increased from 2016 (12.86 ± 14.10 μg·m⁻³) to 2018 (36.76 ± 21.59 μg·m⁻³) and then declined gradually. SOC/OC was larger than 67.0% from 2018 to 2020, implying that more effective synergistic emission reduction measures for carbonaceous aerosol and volatile organic compounds (VOCs) were needed. In the winters from 2016 to 2020, primary organic carbon (POC) concentrations reduced by 76.1% and 87.6% under a light/moderate pollution period (LP) and heavy/severe pollution periods (HPs), respectively. The TCA/PM_2.5 showed a decreasing trend under LP and HP conditions, decreasing by 42.1% and 54.7%, respectively. Source analysis revealed that carbonaceous components were mainly from biomass burning, coal combustion and automotive exhaust emissions in the winters of 2016 and 2020. OC/EC and K⁺/EC analysis pointed out that air pollutant reduction measurements should focus on rectification biomass fuels in the next stage. Compared with 2016, the contributions of automotive exhaust emissions decreased in 2020. OC and EC concentrations decreased due to control measures on automotive exhaust emissions. Full article

In West African cities, the impacts of the air quality on the health of the population is expected to increase significantly in the near future. For the first time to our knowledge, we conducted a high-resolution modeling study over Abidjan (Côte d’Ivoire) using the WRF-Chem model and the simplified GOCART model to simulate carbonaceous aerosols BC and OC, sulfate, dust, sea salt, PM_2.5, and PM₁₀. The simulations were carried out during January and February 2019, a period over which there are databases of observations available. The DACCIWA inventory provided anthropogenic emissions at the regional scale, whereas a new emission inventory has been developed for the city of Abidjan. In 2019, the emissions were 4986.8 Gg for BC, 14,731.4 Gg for OC, and 7751.6 Gg for SO₂. Domestic fires were the primary OC source (7719.5 Gg), while road traffic was the largest BC emitter (2198.8 Gg). Our modeling results generally overestimate urban particle concentrations, despite having a better agreement for those based on the inventory of the city of Abidjan. Modeled concentrations of BC are higher in administrative centers due to road traffic, while OC concentrations are significant in densely populated neighborhoods. Full article

This study investigated the aerosol particle properties and light absorption properties of brown carbon (BrC) by utilizing a seven-wavelength aethalometer, and analyzed NH₄⁺, NO₃⁻, SO₄²⁻, K⁺, K, organic carbon, elemental carbon, levoglucosan, and mannosan in PM_2.5. The research was conducted in a rural area of Jeonnam, South Korea, during the winter season. In addition, the dithiothreitol assay-oxidative potential normalized to 9,10-phenanthrenequinone (QDTT-OP) was investigated throughout the study period. The absorption coefficient was found to be 2.6 to 5.6 times higher at 370 nm compared to 880 nm, suggesting the presence of light-absorbing substances in addition to black carbon (BC) particles. The estimated absorption coefficient of BrC₃₇₀ was 29.9% of the total light absorption coefficient at 370 nm. Furthermore, BrC₃₇₀ exhibited a strong affinity with levoglucosan while showing a weak correlation with K⁺, confirming the suitability of levoglucosan as a tracer for biomass burning. The QDTT-OP was 5.3 nM m⁻³, and highly correlated with the carbonaceous components levoglucosan and mannosan, suggesting a relatively high contribution of biomass combustion emissions to oxidative potential. Further research should be conducted to assess the health risks associated with future PM_2.5 exposure related to biomass burning in the atmosphere. Full article