Large-scale wildfires are essential sources of black carbon (BC) and brown carbon (BrC), affecting aerosol-induced radiative forcing. This study investigated the impact of two wildfire plumes (Plume 1 and 2) transported to Moscow on the optical properties of BC and BrC during August 2022. During the wildfires, the total light absorption at 370 nm (b(abs_370nm)) increased 2.3-3.4 times relative to background (17.30 +/- 13.98 Mm(-)(1)), and the BrC contribution to total absorption increased from 14 % to 42-48 %. BrC was further partitioned into primary (BrCPri) and secondary (BrCSec) components. Biomass burning accounted for similar to 83-90 % of BrCPri during the wildfires. The b(abs_370nm) of BrCPri increased 5.6 times in Plume 1 and 11.5 times in Plume 2, due to the higher prevalence of peat combustion in Plume 2. b(abs_370nm) of BrCSec increased 8.3-9.6 times, driven by aqueous-phase processing, as evidenced by strong correlations between aerosol liquid water content and b(abs_370nm) of BrCSec. Daytime b(abs_370nm) of BrCSec increased 7.6 times in Plume 1 but only 3.6 times in Plume 2, due to more extensive photobleaching, as indicated by negative correlations with oxidant concentrations and longer transport times. The radiative forcing of BrCPri relative to BC increased 1.8 times in Plume 1 and Plume 2. In contrast, this increase for BrCSec was 3.4 times in Plume 1 but only 2.3 times in Plume 2, due to differences in chemical processes, which may result in higher uncertainty in its radiative forcing. Future work should prioritize elucidating both the emissions and atmospheric processes to better quantify wildfire-derived BrC and its radiative forcing.

The influence of aerosols on the Arctic system remains associated with significant uncertainties, particularly concerning black carbon (BC). The polar aerosol station “Island Bely” (IBS), located in the Western Siberian Arctic, was established to enhance aerosol monitoring. Continuous measurements from 2019 to 2022 revealed the long-term effects of light-absorbing carbon. During the cold period, the annual average light-absorption coefficient was 0.7 ± 0.7 Mm−1, decreasing by 2–3 times during the warm period. The interannual mean showed a peak in February (0.9 ± 0.8 Mm−1) then 10 times the lower minimum in June and exhibited high variability in August (0.7 ± 2.2 Mm−1). An increase of up to 1.5 at shorter wavelengths from April to September suggests contribution from brown carbon (BrC). The annual mean equivalent black carbon (eBC) demonstrated considerable interannual variability, with the lowest in 2020 (24 ± 29 ng m−3). Significant difference was observed between Arctic haze and Siberian wildfire periods, with record-high pollution levels in February 2022 (110 ± 70 ng m−3) and August 2021 (83 ± 249 ng m−3). Anthropogenic BC contributed 83 % to the total for the entire study period, and gas flaring, domestic combustion, transportation, and industrial emissions dominated. During the cold season, > 90 % of surface BC was attributed to anthropogenic sources, mainly gas flaring. In contrast, during the warm period, Siberian wildfires contributed to BC concentrations by 48 %. In August 2021, intense smoke from Yakutian wildfires was transported at high altitudes during the region's worst fire season in 40 years.

The article presents the results of the latest studies of the emission and distribution of microparticles in the environment based on monitoring and assessment of the ecological and geochemical state of urbanized areas and river basins. Scientific bases and technologies for geochemical analysis of microparticles in the atmosphere (aerosols, snow and rain), pedosphere (urban soils and road dust) and terrestrial hydrosphere (dissolved and suspended forms of chemical elements in water mass and bottom sediments) have been developed. It is shown that the analysis of microparticles is of key importance for understanding the mechanisms of pollution of the environmental components and the formation of technogenic geochemical anomalies in the Moscow metropolis and other cities. Our research made it possible to identify an association of chemical elements that enriches almost all components of the urban environment. It includes antimony, cadmium, copper, tungsten, zinc, lead, bismuth, tin, and molybdenum .With multiple emissions from various pollution sources in large cities, the Source Apportionment technology was used to quantify the contributions of sources to the pollution of the studied environments. The PMF receptor model was used for the first time to determine the contribution of dust, transport and industrial sources to the pollution of the Moscow atmosphere, which is necessary for assessing the air quality and geochemical load on terrestrial landscapes. The influence of long-range transport was estimated by calculating probable directions (reverse trajectories) of air advection using the NOAA HYSPLIT transport-dispersion model. Possible sources of metals and metalloids (MMs) in microparticles of Moscow road dust were identified using the PCA-MLR model. Statistical analysis of the experimental material allowed establishing the main factors and mechanisms that determine the spatial distribution of contamination of road dust and urban soils with MMs, as well as their most important carrier phases specific to different pollution sources. Based on the survey of the major rivers of Russia, a methodology and technology for hydrogeochemical analysis of river basins was elaborated. The analysis covers high-frequency (daily, weekly), seasonal and interannual variability of hydrological parameters, concentrations of chemical elements in dissolved and suspended forms, their particle size distribution, as well as chemical elements flows in river basins.

Wildfires are an important source of particulate matter in the atmosphere and have a significant impact on the regional atmospheric environment through atmospheric transportation.In this study,PM10 samples were collected at Moscow urban background from June to September 2022,covered the periods of wildfires occurred in the Ryazan forest,200 km from the city.Mass concentrations of carbonaceous components(organic carbon,OC,and elemental carbon,EC)and water soluble inorganic ions(WSlls)were analyzed to assess the impact of wildfires on the PM10 composition.Based on backward air mass trajectories and fire spot maps analysis,the two pollution events with significantly increased PM10 concentrations(Plume 1 and Plume 2)that occurred in August were identified.During Plume 1 and Plume 2,averaged PM10 were 44.1±7.2 and 71.0±19.2 μg/m3,respectively,1.9 and 3.0 times higher than during urban background period,nighttime PM10 concentrations were higher than daytime.SOC concentrations increased by 2.0 and 4.8 times,respectively,compared to urban background(3.9±1.9 μg/m3).OC and EC concentrations(Plume 1:18.8±7.0 and 3.9±1.2 μg/m3;Plume 2:32.5±15.1 and 5.4±2.4 μg/m3)were significantly higher than those during urban background period(7.7±2.8 and 2.1±1.0 μg/m3).Proportion of organic matter(OM)in PM10 and SOC in OC increased to 68.3％and 73.2％and up to more than 60％.The influence of the transportation of wildfire plumes increased the proportion of OM,especially SOC.The total concentrations of WSlls during Plume 1 and Plume 2 increased by 1.6 and 4.2 times compared to urban background(1.5±0.9 μg/m3),and the proportion of secondary inorganic ions(SNA)in WSlls also increased.Under plumes impact,significant correlations between SNA and K+were found,and NO3/SO4-were less than 1,different from urban background(NO3-/SO42-＞1),indicating that SNA contributed by wildfire smoke.By comparison of nitrogen oxidation(NOR)and sulfur oxidation(SOR)rates,it indicated the promotion of the conversions of SO2 and NO2 to SO4-and NO3-as a result of wildfire smoke plumes transportation to the megacity,especially the conversion of SO2 at night.

Biomass burning (BB) has a major impact on air quality and population health, with the brown carbon (BrC) of special concern as an important source of pollution and absorbing incoming radiation. The impact of BB was quantified in an urban area of Moscow, the northern gas-fuel heated European megacity, during warm and cold seasons. Real-time measurements of aerosol optical properties were performed by an aethalometer. Heating and non-heating periods are marked by Absorption Angstrom exponent (AAE) equal 1.1 and 1.2, spring agricultural and summer wildfires by 1.3 and 1.4, respectively. Light absorption babs of 10 f 9 Mm-1 at 880 nm and 29 f 27 Mm-1 at 370 nm was independent on heating activity. No significant seasonal difference was revealed by mass absorption coefficient for black carbon (BC) of 13.5 m2 g-1 and BrC of 0.9 m2 g-1. BC contribution to total absorption dominated in all wavelength ranges and seasons. During heating period, BrC contribution to total absorption at 370 nm (%babsBrC) was 16 f 21 %, lower than in other European and Asian megacities where populations widely burn biomass and coal. It was 24 f 31 % in spring due to agricultural fire impact and increased BB activity because of the population migration out of the city during the May holiday. Ryazan wildfire plumes affected Moscow, with babs(880) and babs(370) increase 1.7 and 2.4 times, respectively, with a high % babsBrC of 37 +/- 59 %, and strong BrC absorption capacity in both day and nighttime. The relative absorption forcing of BrC compared to BC was estimated to range between 36.2 +/- 1.1 % and 29.8 +/- 2.7 % in ultraviolet and visible radiation range, respectively. Backward trajectory cluster and concentration weighted trajectory analyses revealed the regional origin of BB sources, coinciding with areas of observed wildfires. Collocated 12 h sampling and chemical composition analyses of BB tracers (levoglucosan and K+) identified the emission sources by significant correlations with BrC absorption. Four factors of BrC apportionment were identified via positive matrix factorization, showing contributions from fossil fuel combustion and secondary organic (82 %), and BB (18 %). As a result, regional population activity and spring and summer wildfires highlighted the uniqueness of Moscow as the northern gas-fuel heated megacity for BB impact studies in Europe and Asia.

Among globally relevant combustion sources, such as diesel emission and biomass burning, gas flaring remains the most uncertain. In this study, small-scale turbulent gas flaring was used to characterize particulate emissions produced under different operating conditions, such as various burner diameters and exit velocities. The composition of the fuel was also varied by modifying the percentage of methane, ethane, propane, butane, N2, and CO2, which are the predominant constituents in the upstream oil and gas industry. A broad suite of physical, chemical, and microscopic techniques was employed for analysis, and scanning electron microscopy showed the generated soot agglomerates to be composed of primary spherules that were 30 ± 10 nm in diameter. Additionally, high-resolution transmission electron microscopy, used to determine the length, tortuosity, and separation of individual graphene fringes on the primary particles, revealed a fullerenic, multiple-nuclei internal structure. Single-particle analysis revealed the dominance of elemental carbon vs. oxidized and metal-contaminated particles, and infrared spectroscopy showed the presence of alkanes and aromatics with oxygenated compounds. Intercomparing the microstructure and the composition, we also concluded that the vast majority of particles are hydrophobic.

Impact of traditional biomass burning activities on regional air quality is a major environmental concern. Measurement campaigns were performed during post-harvesting activities in the Ba Vi region in Hanoi in May–June of 2015 and 2016. To quantify the source for regional haze the sampling of rice straw burning emissions was performed on fields. Carbonaceous (OC, EC, BrC) fractions, heavy metals, organic and ionic composition, and microstructure were characterized. A set of functionalities (hydroxyl, aliphatic, carbonyl, carboxylate, and nitro groups) revealed a functional marker of pile combustion. Optical, microstructural, and chemical analyses of environmentally-dangerous pollutants from traffic and cooking sources provided characteristics and functional markers of different pollution sources. Chemical features of rice straw burning were identified on the Ba Vi site during the haze episode of 2015, when PM10 mass approached the high smoke intensity, up to 167 µg m−3. Small-scale meteorology affected PM10, OC and EC, and ion mass in days of highest relative humidity and fogs. In days of highest smoke OC dominated PM10 mass by up to 42

Reliable assessment of the impact of Siberian boreal forest wildfires on the environment and climate necessitates an improved understanding of microphysical and chemical properties of emitted aerosols. Smoldering, flaming and mixed fires of typical Siberian biomass (pine and debris) were simulated during a small-scale study in a Large Aerosol Chamber (LAC). Individual particle analysis of PM10 and PM2.(5) smoke morphology and elemental composition revealed a strong dependence on combustion temperature, i.e., a dominant abundance of soot agglomerates versus roughly spherical organic particles in the flaming and smoldering phase, respectively. Cluster analysis of smoke microstructure was used to apportion the emitted particles into major characteristic groups: Soot and Organic, which accounted for around 90% and 60% of total particle numbers emitted from the flaming and smoldering fires, respectively. Carbon fractions and inorganic ion analysis supported the identification of particle types representative of combustion phase and biomass type. Elemental carbon (EC) particles from flaming fires comprised approximately 25% of Group Soot, in good agreement with a high EC fraction in total carbon of around 65% and low organic carbon (OC)/EC ratio near 0.5. Smoldering fires of pine and debris produced exclusively organic particles with high OC/EC ratios of 194 and 34, respectively. Small quantities of elemental constituents in biomass were vaporized during combustion and produced internally/externally mixed fly ash in Group Ca-, Si-, and Fe-rich of significantly less abundance. Ca, Cl, S, and Mg were more frequently distributed elements in pine than debris smoke. Sulfates and nitrates produced from gas-to-particle reactions formed Group S- and N-rich. During time evolution of smoke volatile inorganic compounds were condensed as potassium chlorides and sulfates into a newly formed Group K, Cl-rich. Quantification of Siberian biomass smoke microstructure by chemical micromarkers enables aerosols to be classified with respect to a source type assigned to Siberian wildfires.

As large-scale peat burning emissions can severely impact the environment and human health, it is crucial to assess the characteristics of smoke aerosol at the source and at down-wind locations. From March until late summer in 2014, the Tver region, north of the city of Moscow, was considerably affected by long-lasting peat bog fires. Peat bog smoldering emissions from three types of smoke (underground, inside grass, and above grass) were analyzed by an extensive suite of instrumentation that sampled and measured their optical and chemical properties. The particle composition was characterized by organic species with high OC/EC ratios (10–20), with water-soluble organic carbon (WSOC) and levoglucosan (Lev) comprising the largest fraction, up to 30 and 9

Cities are highly interconnected systems where specific interactions between various urban environments occur due to the Urban Heat Island (UHI) and Urban Pollution Island (UPI) effects. Four compartments of the environment (atmospheric air, road dust, streamflow, and people) are discussed for Moscow city. Long-term meteorological, radiative, air quality, and precipitation measurements, the non -hydrostatic regional numerical COSMO model, and extensive hydrological and geochemical sampling were used. To characterize mortality and UPI interaction, a family of distributed lag non-linear models (DLNM) was applied. The study reveals increased aerosols concentrations which reduce the incoming solar radiation and increase the atmospheric longwave radiation. UHI strengthens the low -troposphere convergence due to urban breeze circulation and atmospheric circulation due to elevated surface roughness, the effect which leads to 11.6% heaviest precipitation increase compared to background values. Increased precipitation doubles streamflow rates and enhances the contribution of rain floods to annual flow. Similar geochemical associations with Sb, W, Zn, Cd, Pb, and Cu were found in aerosol PM 10 , indicating transport and road dust impact. Finally, associations between high temperatures and human mortality which are generally stronger at high levels of air pollution for both PM 10 and NO 2 , and for lag 1 day and 2-6 days are discussed.

Aerosol particles significantly impact the regional environment, including climate change, specifically in periods of extensive biomass burning. The major agricultural and domestic combustion emission sources were assessed in near-source and ambient monitoring campaigns in northwestern Vietnam during the dry season. The composition and microstructure of on-field burning and cooking emissions were analyzed with a variety of techniques. A wide range of observed PM_(2.5) mass concentrations was categorized according to the smoke level, supported by the evolution of carbon fractions (OC and EC) as well as ionic species and molecular tracers (K^+, levoglucosan, and mannosan). The OC/EC and individual organic compound ratios on days with high smoke levels indicate smoldering combustion of softwood and other local biomass species, impacting aerosol composition at the regional level. Acid and non-acid carbonyls, carboxylates, and aliphatic carbon functionalities in the PM_(2.5) size fraction evolved with increasing smoke intensity, together with carbonates in coarse (PM_(1-2.5) and PM_(2.5-10)) size fractions, indicating a large impact of smoke emissions and soil lifted up by the intense fires. Biomass burning influence increased the abundance of soot and organic particles in the submicron fraction from 12% at low to 59% and 68% at moderate and high smoke levels, respectively. Smoke micromarkers of local biomass burning source emissions determined the microstructure of ambient aerosols representative for northern Southeast Asia.

ABSTRACTThe growing concern about air quality and the impact exhaust particles can have on the environment has resulted in the increased use of alternative fuels. A sampling campaign from a conventional heavy diesel engine operated in typical transient cycle or steady-state condition, and running on diesel, 30% biodiesel in diesel, and 100% biodiesel was carried out. The particulate composition was characterized using Fourier Transform Infrared (FTIR) spectroscopy, Two-step Laser Mass Spectrometry (L2MS), Secondary Ion Mass Spectrometry (SIMS), thermo-optical analysis, and capillary electrophoresis. Elemental carbon is demonstrated to decrease from diesel to 100% biodiesel, in agreement with the evolution of aromatic bands and the MS abundance of Cn– fragments, while organic carbon exhibits a constant level irrespective of the working regime. Aliphatic, aromatic, carboxyl, carbonyl, hydroxyl functionalities, and nitro compounds are found to depend on the engine-working regime. Mass spectra are mainly characterized by alkyl fragments (CnH2n+1+), associated to normal and branched alkanes, PAHs and their alkylated derivatives. The addition of biodiesel to diesel changes the particulate composition towards more oxygenated constituents, such as carbonyl groups attributed to methyl ester CH3O+ fragments of unburned biodiesel. Fuel-specific fragments have been identified, such as C3H7O+ for diesel, and C2H3O2+ and CH3O– for biodiesel. Nitrogenized compounds are revealed by -NO2 functionalities and N-containing fragments. Principal Component Analysis (PCA) was successfully applied to discriminate the engine operating conditions, with a higher variance given by the fuel, thus allowing to better evaluate the environmental impacts of alternative energy source emissions.

Poor air quality in workplaces constitutes a great concern on human health as a good fraction of our time is spent at work. In Greece, very unique workplaces are the street corner kiosks, which are freestanding boxes placed on sidewalks next to city streets and vehicular traffic, where one can find many consumer goods. As such, its employees are exposed to both outdoor and indoor air pollutants. Very few studies have examined the occupational exposure of kiosk workers to air pollutants, and thus the magnitude of this unique indoor and outdoor exposure remains unknown. The objective of this study is to investigate and compare the levels of indoor and outdoor particulate matter (PM10 and PM2.5), ultrafine particles (UFPs) and black carbon (BC) in different kiosks located in Athens, Greece, in urban-traffic and urban-background environments. Continuous measurements of the above-mentioned pollutants were carried out on a 24-h basis over 7 consecutive days at three kiosks from September to October 2019. Indoor PM10 concentrations in the urban kiosk ranged from 19.0 to 44.0 μg/m3, PM2.5 values ranged from 14.0 to 33.0 μg/m3, whereas BC concentrations ranged from 1.2 to 7.0 μg/m3 and UFPs from almost 9.5 to 47.0×103 pt/cm3. Outdoor PM10 and PM2.5 measurements ranged from 29.0 to 59.0 μg/m3 and from 22.0 to 39.0 μg/m3, respectively. BC outdoor concentrations ranged from 1.1 to 2.2 μg/m3. The mean hazard quotient (HQ) for PM10 (4.9) and PM2.5 (4.7) among all participants was > 1. The health risk of exposure to PM10 and PM2.5 was found to be at moderate hazard levels, although in some cases we observed HQ values higher than 10 due to high PM10 and PM2.5 concentrations in the kiosks. Overall our study indicates that people working at kiosks can be exposed to very high concentrations on particulate pollution depending on a number of factors including the traffic that strongly depends on location and the time of the day

A lack of understanding about the impact of Siberian wildfire emissions on the environment necessitates the characterization of biomass burning aerosol hygroscopicity. Flaming fires of typical Siberian biomass (pine and debris) were simulated during small-scale combustion experiments in a Large Aerosol Chamber (LAC). Analyses of individual particles with respect to morphology and elemental composition allows the separation of freshly-produced smoke into five fractions with the elemental carbon, chain soot agglomerates, irregular internally mixed soot, and distinct irregular minerals of fly ash containing S, Ca, Al, and Si. Aging in a dark chamber leads to an appearance of the fraction with inorganic inclusions such as KCl and CaCl2. Categorization of fresh-emitted and aged particles on hydrophobic, hydrophilic, and hygroscopic ones is performed. The criteria for categorization are extended from fossil fuel high-temperature combustion, based on a concept of water uptake by soot particles and utilization of a number of reference soots with known oxygen content and mixtures with sulfates and other inorganic salts. We show how the hydration properties of emitted smoke particles and inorganic inclusions can increase the initial level of smoke hygroscopicity.

Assessments of air quality in industrial cities are receiving much attention, especially in regions sensitive to the ecological and climate changes. The atmospheric aerosol loading was studied in the city of Novy Urengoy during the summer–autumn of 2023. Particle number concentration and the mass concentration of particles with a size less than 10 µm (PM10) and 2.5 µm (PM2.5), as well as black carbon (BC), were measured by the mobile Aerosol Complex. The portion of fossil fuel combustion (FF

Wildfires in Siberia generate large amounts of aerosols, which may be transported over long distances and pose a threat to the sensitive ecosystem of the Arctic. Particulate matter (PM) of aged wildfire plumes originating from Yakutia in August 2021 was collected in Nadym and on Bely Island (both in northwestern Siberia). An advanced analysis of the chemical composition of aerosol particles was conducted through a multi-wavelength thermal–optical carbon analyzer (TOCA) coupled to resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS) as well as through ultra-high-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). In Nadym, concentrations of organic carbon (OC) and elemental carbon (EC) peaked at 100 and 40 µg m−3, respectively, associated with Angström absorption exponents for 405 and 808 nm (AAE405/808) between 1.5 and 3.3. The weekly average on Bely Island peaked at 8.9 µg m−3 of OC and 0.3 µg m−3 of EC and AAE405/808 close to unity. In particular, ambient aerosol in Nadym had a distinct biomass burning profile with pyrolysis products from carbohydrates, such as cellulose and hemicellulose, as well as lignin and resinoic acids. However, temporarily higher concentrations of five- and six-ring polycyclic aromatic hydrocarbons (PAHs), different from the PAH signature of biomass burning, suggest a contribution of regional gas flaring. FT-ICR MS with electrospray ionization (ESI) revealed a complex mixture of highly functionalized compounds, containing up to 20 oxygen atoms, as well as nitrogen- and sulfur-containing moieties. Concentrations of biomass burning markers on Bely Island were substantially lower than in Nadym, flanked by the appearance of unique compounds with higher oxygen content, higher molecular weight, and lower aromaticity. Back-trajectory analysis and satellite-derived aerosol optical depth suggested long-range transport of aerosol from the center of a Yakutian wildfire plume to Nadym and from the plume periphery to Bely Island. Owing to lower aerosol concentrations in the plume periphery than in its center, it is demonstrated how dilution affects the chemical plume composition during atmospheric aging.

In the complex situation with the plurality of emissions, the important research task of assessing the air quality and potential sources through aerosol composition analyses remains for Moscow’s megacity environment. The light absorption, PM10 mass concentration, aerosol composition, and meteorological parameters in this urban background were measured during spring 2017, a period characterized by significant changes in the air temperature, mass advection, and solar radiation. The organic and elemental carbon (OC and EC) and 76 organic compounds, e.g., alkanes, polycyclic aromatic hydrocarbons (PAHs), oxidized PAHs, hopanes, anhydrosugars, polyols, primary and secondary saccharides, and HULIS, as well as 13 ions, including K+, a marker of biomass burning, have been quantified to determine the carbonaceous and inorganic chemical profiles of the aerosol. The correlation between the absorption Ångström exponent (AAE) and the levoglucosan concentration reveals the relative contributions of agricultural fires and residential biomass burning (BB) nearby to the urban aerosol composition. Combining detailed analytical and statistical approaches, we have identified and analyzed the specific chemical compounds that most accurately represent the variability of the aerosol composition. Principal component analysis (PCA) highlights the main factors for marker species related to gasoline/diesel traffic, BB, biogenic activity, and secondary formation in the atmosphere. Distinguishing the BB-affected periods allows us to evaluate daily changes in the aerosol composition in relation to the transported air masses and detected fires in the areas surrounding Moscow.

Globally the impact of COVID-19 lockdown on environmental pollution is evidenced. How significant it was due to social and working restrictions during different pandemic waves is still uncertain. Aerosol black carbon (BC) in the Moscow megacity background is measured during first wave COVID-19 lockdown and recovery periods in spring and summer of 2020, and at the same times in 2021 when pre-lockdown and lockdown of the third pandemic wave occurred. Economic and population activities in conjunction with meteorological parameters and air mass transportation are evaluated by studying the variability and concentration levels of black carbon. Because the strict social and working restrictions in lockdown 2020 the mean BC concentration dropped down to 1.5 ± 0.9 µg m−3. The portion of biomass burning (BB

High population and a wide range of activities in a megacity lead to large-scale ecological consequences which require the assessment with respect to distinct characteristics of climate, location, fuel consumption, and emission sources. In-depth study of aerosol characteristics was carried out in Moscow, the largest megacity in Europe, during the cold period (autumn and winter) and in spring. PM10 chemical speciation based on carbonaceous matter, water-soluble ions, and elements was carried out to reconstruct the PM mass and evaluate the primary and secondary aerosol contribution. For the whole study period organic matter, mineral dust, and secondary inorganic/organic accounted for 34, 24, and 16 % of PM10 mass, respectively. PM10, OC, and EC approached a maximum in spring and decreased in winter. Mineral dust seasonal fraction increased from spring (17 %) to autumn (32 %), and then decreased in winter (22 %). Secondary inorganic aerosols (SIA) in opposite showed the maximum 27 % in winter. K+ marked the residential biomass burning in the region surrounding a megacity in spring and autumn, agriculture fires in spring. In winter primary aerosol contribution dropped down 56 % while secondary approached practically equal 44 %. Source factors with the relative contributions are quantified, namely city dust (26 %), traffic (23 %), industrial (20 %), biomass burning (12 %), secondary (12 %), and de-icing salt (7 %); they were significantly varying between the cold heating period and springtime. The relevance of sources to meteorological parameters and mass transportation is investigated by using both bivariate polar plots and Lagrangian integrated trajectory (HYSPLIT) model. Trajectory clustering demonstrates regional sources being crucial contributors to PM10 pollution. Aerosol speciation and source apportion factors identify the differences of the Moscow urban background among large European and Asian cities due to northern climate conditions, fast construction, long-range transport from industrial -developing area surrounding a city, regional biomass burning preferably in spring and autumn, and winter road management.