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The morphological properties of biogenic particles in the near-surface aerosol composition in the Moscow Metropolitan Area were studied by scanning electron microscopy. Analysis data on aerosol samples (2019–2022) obtained during a complex experiment at the Institute of Atmospheric Physics, Russian Academy of Sciences, to study the variability of the physicochemical properties of bioaerosol particles under various meteorological conditions were summarized. The main types of bioaerosol particles were determined, as were their shapes and sizes. For the first time, brochosomes were detected in the surface aerosol in Moscow during field aerosol observations. [ABSTRACT FROM AUTHOR]

Calcium is known to be enriched in sea spray aerosols (SSA), but its controlling factors and individual mixing states remain ambiguous. Here, we investigate the impact of various environmental factors on the water-soluble calcium (Ca2+) distribution in SSA through R/V Xuelong cruise observations over the Ross Sea, Antarctica, from December 2017 to February 2018. We observed enhanced Ca2+ enrichment in aerosol samples at lower temperatures (< -3.5 °C), lower wind speeds (< 7 m s-1) and in the presence of sea ice. Further individual particle mass spectral analysis indicated that considerable fractions of calcium in SSA likely bind with organic matter (a single-particle type, OC-Ca), which may be neglected in current water-soluble estimation of Ca2+ enrichment. Also, this is the first time that a calcium-dominated single-particle type has been observed in the Antarctic atmosphere. We suggest that a broader focus on individual OC-Ca and its subsequent environmental behavior should be included in future Antarctic atmospheric modeling. Given the context of global warming and sea ice retreat, an understanding of the mechanisms of calcium enrichment and mixing state of individual particles involved is valuable for further recognizing the aerosol-cloud-climate interactions in the Antarctica summer. [ABSTRACT FROM AUTHOR]

Black carbon (BC) strongly absorbs solar radiation, contributing to global warming. Absorption enhancement of BC particles is difficult to quantify due to an inadequate representation of their complex morphology and mixing structures, as well as interaction with radiation. Here, we apply a 3D method accounting for detailed BC mixing structures to predict the absorption enhancement of individual BC particles (Eabs) and the total BC particle population (Eabs, bulk). The diverse range of mixing structures in individual BC particles leads to variable Eabs that could hardly be predicted by empirical approximations. We find that the volume proportion of the BC embedded in coating (F) determines Eabs when the particle to BC core diameter ratio (Dp/Dc) is larger than 2.0. Our findings reveal the potential mechanism behind the differences in observed and modeled Eabs, bulk. The framework builds a bridge connecting the microscopic mixing structure of individual BC particle with Eabs, bulk. Plain Language Summary: Absorption by black carbon (BC) in the atmosphere strongly affects radiative balance and global climate. The large discrepancies in observed and modeled BC absorption enhancements raise a hot debate. Through applying a new 3D shape model based on electron microscope observations, we propose a new framework that estimates BC absorption enhancement through accounting for mixing structure diversity in individual particles. Our results reveal that the diverse range of mixing structures in individual particles in ambient air leads to complex absorption enhancement that could hardly be predicted by the empirical approximation. The bulk absorption enhancements based on diverse mixing structures provide an explanation for the globally disparate results from laboratory and field observations. The new framework linking microphysical structures to bulk BC optical properties can be used to improve assessment of climate impact. Key Points: The impact on absorption enhancement by embedded fraction is significantly enhanced when BC particle to core diameter ratio >2.0The embedded fraction and coating thickness in aged BC particles can lead to significant differences in bulk absorption enhancementA new bridge is built to connect the microscopic mixing structure of individual aged BC particles with bulk absorption enhancement of BC [ABSTRACT FROM AUTHOR]

This scoping study presents an investigation of the total and bioaccessible mercury concentrations in road dust (RD) from three international urban sites, where a one-off sampling campaign was conducted at each. This was done to address the hypothesis that the matrix in which mercury is found influences its ability to become accessible to the body once inhaled. For that purpose, the samples were analysed for total and pulmonary bioaccessible mercury and the data compared to the chemical structure of individual particles by SEM. The results obtained from this study suggest that a high mercury content does not necessarily equate to high bioaccessibility, a phenomenon which could be ascribed to the chemical character of the individual particles. It was found that the Manchester samples contained more pulmonary soluble mercury species (as determined by elemental associations of Hg and Cl) in comparison to the other two samples, Curitiba, Brazil, and Johannesburg, South Africa. This finding ultimately underlines the necessity to conduct a site-specific in-depth analysis of RD, to determine the concentration, chemical structure and molecular speciation of the materials within the complex matrix of RD. Therefore, rather than simply assuming that higher bulk concentrations equate to more significant potential human health concerns, the leaching potential of the metal/element in its specific form (for example as a mineral) should be ascertained. The importance of individual particle behaviour in the determination of human health risk is therefore highlighted. [ABSTRACT FROM AUTHOR]

To investigate the particle sources before, during, and after the 2022 Beijing Winter Olympic and Paralympic (WOP) in Beijing, ambient particles were passively collected from January to March 2022. The physicochemical properties including morphology, size, shape parameters, and elemental compositions were analyzed by the IntelliSEM EPAS (an advanced computer-controlled scanning electron microscopy [CCSEM] system). Using the user-defined classification rules, 37,174 individual particles were automatically classified into 27 major groups and further attributed to seven major sources based on the source-associated characteristics, including mineral dust, secondary aerosol, combustion/industry, carbonaceous particles, salt-related particles, biological particles, and fiber particles. Our results showed that mineral dust (66.5%), combustion/industry (12.6%), and secondary aerosol (6.3%) were the three major sources in a wide size range of 0.2–42.8 μm. During the Winter Olympic Games period, low emission of anthropogenic particles and favorable meteorological conditions contributed to significantly improved air quality. During the Winter Paralympic Games period, more particles sourced from the dust storm, secondary formed particles, and the adverse meteorological conditions resulted in relatively worse air quality. The secondary aerosol all decreased during the competition period, while increased during the non-competition period. Sulfate-related particles had explosive growth and further aggravate the pollution degree during the non-competition period, especially under adverse meteorological conditions. These results provide microscopic evidence revealing variations of physicochemical properties and sources in response to the control measures and meteorological conditions. [Display omitted] • Mineral dust, combustion/industry, and secondary aerosol were the top three sources of aerosol particle (0.2–42.8 μm). • Notable decreases in anthropogenic particles were observed during competition period by IntelliSEM EPAS. • Dramatic rise in secondarily formed particles mainly exacerbated pollution levels during non-competition period. • Winter Olympics had better air quality primarily benefited from significant emission reductions and favorable weathers. • Winter Paralympics faced deteriorated air quality due to dust storm and haze event under adverse weather. [ABSTRACT FROM AUTHOR]

To study the effect of fireworks/firecrackers (FF) display on aerosol particles, the chemical composition and morphology of fine aerosol particles (PM 2.5) collected in a rural valley of north China in the Chinese New Year's Eve (CNYE) were analyzed. The results showed that PM 2.5 was much lower in the 2022 CNYE with little influence by FF due to the strict no-FF display policy for the 2022 Winter Olympic Games. In contrast, PM 2.5 was significantly affected by FF display in the 2023 CNYE with the maximum hourly PM 2.5 mass concentrations reaching 1200 μg m−3. The value was even much higher than that in near-by cities. Chemical analysis showed that organic matter (24.5 wt% of total PM 2.5) was the most abundant in the CNYE, followed by K+ (15.3 wt%), SO 4 2− (12.3 wt%), and Cl− (9.9 wt%). The mass concentrations of K+, Mg2+, Cu, Sr, and Ba were as 22.0 to 41.4 times as those before the CNYE. The concentrations of elemental carbon, Cl−, SO 4 2−, and Ti were as 3.7 to 12.3 times as those before the CNYE. Further analysis by scanning electron microscope coupled with energy dispersive X-ray spectrometer revealed that carbonaceous particles in the CNYE contained more S, Cl, K and heavy metals compared with that before the CNYE. Most of the non-carbonaceous particles in the CNYE were K-rich, Mg-rich, Al-rich, and Ba-rich, with spherical and near-spherical shapes, which were much different from those before the CNYE with irregular shapes. The different morphologies of non-carbonaceous particles can have much different optical properties, which should be further evaluated. The results above suggested that the PM 2.5 mass concentration in rural valleys in the CNYE was extremely high in a short time and more attention should be paid in future policy making to improve air quality. • Air quality in rural valleys was more impacted by fireworks/firecrackers (FF) display than in near-by cities. • OM, K+, SO 4 2−, and Cl− were much high in rural valleys affected by FF display. • FF display emitted more spherical shaped K-rich, Al-rich, Mg-rich and Ba-rich particles. [ABSTRACT FROM AUTHOR]

To set up a sampling and analysis strategy for particulate matter (PM) based on the time periods used in international standards is often inadequate for assessing the impact of day/night cycles or episodic emissions on urban air quality. To obtain a detailed physico–chemical characterization of urban PM when concentrations exceed the regulatory thresholds, a new rotary cascade impactor named the Time-Resolved Atmospheric Particle Sampler (TRAPS) was designed and tested for coarse and fine particle sampling. The TRAPS implementation, coupled with Optical Particle Counter measurements, provides time-resolved samples that can be analyzed by a wide range of single-particle analysis techniques. The TRAPS theoretical design was verified experimentally. Experimental cut-off diameters of 1.32 and 0.13 µm, respectively, for coarse and fine stages, were found in good agreement with theoretical values. Additionally, good trace separation, preventing inter-sample contamination, was evidenced by Scanning Electron Microscopy (SEM). The homogeneous distribution of particles of different types over a trace was also verified. As a case study, automated SEM-EDX analysis of 2500 particles, collected during two pollution peaks of a transient PM2.5 pollution event, revealed that individual particles’ chemical composition was influenced by local sources during the first pollution peak, and mainly transported during the second peak.

Abstract Traffic vehicles, many of which are powered by port fuel injection (PFI) engines, are major sources of particulate matter in the urban atmosphere. We studied particles from the emission of a commercial PFI-engine vehicle when it was running under the states of cold start, hot start, hot stabilized running, idle and acceleration, using a transmission electron microscope and an energy-dispersive X-ray detector. Results showed that the particles were mainly composed of organic, soot, and Ca-rich particles, with a small amount of S-rich and metal-containing particles, and displayed a unimodal size distribution with the peak at 600 nm. The emissions were highest under the cold start running state, followed by the hot start, hot stabilized, acceleration, and idle running states. Organic particles under the hot start and hot stabilized running states were higher than those of other running states. Soot particles were highest under the cold start running state. Under the idle running state, the relative number fraction of Ca-rich particles was high although their absolute number was low. These results indicate that PFI-engine vehicles emit substantial primary particles, which favor the formation of secondary aerosols via providing reaction sites and reaction catalysts, as well as supplying soot, organic, mineral and metal particles in the size range of the accumulation mode. In addition, the contents of Ca, P, and Zn in organic particles may serve as fingerprints for source apportionment of particles from PFI-engine vehicles. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Carbonaceous aerosol particles emitted from biomass burning (BB) have a large impact on the global climate. In particular, tarball particles (TBs), which are spherical organic aerosol particles, account for a large proportion of aerosol particles from BB. In this study, we collected aerosol particles over the western North Pacific and analyzed them using transmission electron microscopy with energy-dispersive X-ray spectroscopy (TEM-EDX) to reveal their shape and composition. We detected TBs and organic carbon particles originating from Siberian forest fires. To the best of our knowledge, this is the first case in which a large number of TBs have been found over the Pacific Ocean far from the BB source. The spherical shapes of the TBs were maintained even after long-range transport. In addition, our individual analysis of TBs showed that the size and composition of TBs differ depending on the air mass origin. The occurrence and microphysical properties of TBs are important to accurately evaluate the impact of TBs on climate. Our results imply that TBs can be transported to the Arctic and have an influence on radiative forcing over the ocean and in the Arctic.

Many studies indicate that the atmospheric environment over the southern part of the Tibetan Plateau is influenced by aged biomass burning particles that are transported over long distances from South Asia. However, our knowledge of the particles emitted locally (within the plateau region) is poor. We collected aerosol particles at four urban sites and one remote glacier site during a scientific expedition to the southeastern Tibetan Plateau in spring 2010. Weather and backward trajectory analyses indicated that the particles we collected were more likely dominated by particles emitted within the plateau. The particles were examined using an electron microscope and identified according to their sizes, shapes and elemental compositions. At three urban sites where the anthropogenic particles were produced mainly by the burning of firewood, soot aggregates were in the majority and made up >40% of the particles by number. At Lhasa, the largest city on the Tibetan Plateau, tar balls and mineral particles were also frequently observed because of the use of coal and natural gas, in addition to biofuel. In contrast, at the glacier site, large numbers of chain-like soot aggregates (~25% by number) were noted. The morphologies of these aggregates were similar to those of freshly emitted ones at the urban sites; moreover, physically or chemically processed ageing was rarely confirmed. These limited observations suggest that the biomass burning particles age slowly in the cold, dry plateau air. Anthropogenic particles emitted locally within the elevated plateau region may thus affect the environment within glaciated areas in Tibet differently than anthropogenic particles transported from South Asia. [ABSTRACT FROM AUTHOR]

People inhabiting the Tibetan Plateau rely for survival on the yak, the region's native cattle. One of the important products of yak is dung, which has been served as cooking and heating fuels in the traditional Tibetan pastoralist society for several thousand years. The indoor air quality (IAQ) at eight residential homes with altitudes ranging from 3212 m to 4788 m was investigated in November 2012 to obtain a shot-term profile of emission from combustion of dried yak dung as biofuel in pastoral and agro-pastoral regions on the Tibetan Plateau. The indoor temperature, relative humidity, CO2 and mass concentrations of PM2.5 were monitored for around a 4-h period (5 kg dried fuel was consumed) at each site. Filter-based aerosol samples were also collected to characterize their elemental compositions, water-soluble ions, carbonaceous species and individual particle morphologies. The results showed that combustion of solid biomass fuel in cast-iron stove is the preliminary source of indoor particulate pollution. The average indoor and outdoor PM2.5 mass concentrations were 330.7 and 29.1 μg/m3, respectively. Individual particle analysis showed that most of the particles in smoke from dung burning were in the submicrometer size range. Regular and irregular organic balls and soot aggregates were the predominant species in the smoke (>90% in numbers). The data set in this study can provide significant basis for IAQ and epidemiology study on the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Particles with diameters of 2.5 μm and smaller (PM 2.5) contain various trace elements and potentially influence human health. Physical and chemical features of individual particles and their concentrations with detailed time trends provide useful information for an accurate estimation of the sources and potential toxicity of PM 2.5. Although many studies have measured these features for relatively common elements (e.g., Fe, Zn, and Pb), diurnally concentrations changes and mixing states of particles containing trace elements (below 1 ng m−3) have not been explicitly analyzed. In this study, we observed atmospheric concentrations of 44 elements in PM 2.5 using a real-time observation technique (GED-ICP-MS) at Fukuoka, western Japan, during the winter and spring of 2018. As a result, various elements were detected in anthropogenic air masses from long-range transports. We also sampled aerosol particles every 3 h and analyzed their shapes, mixing states, and compositions using transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy to demonstrate particle occurrences containing trace elements at an individual scale. We especially focused on the abundance and physicochemical features of aerosol particles containing trace elements, such as As, Ga, Rb, Mo, Cd, Cs, and Tl. The element group Ga, Rb, and Cs and a pair of As and Cd showed significant correlations and we succeeded to observe three Ga-bearing particles, seven As-bearing particles, and three Cd-bearing particles. Moreover, we introduce particle features containing Mo and Tl, which were not reported in previous studies. Our results have implications for understanding the occurrence of trace elements in the atmosphere, identifying aerosol sources, and evaluating the influences of aerosol particles on human health. [Display omitted] ● Physical and chemical particle features containing trace elements were observed. ● Atmospheric concentrations of trace elements (below 1 ng m−3 on average) in PM2.5 were observed with time resolutions of five or 7 min. ● Most particles containing trace elements (Ti, Co, Ga, Zr, Mo, Ag, Sn, Sb, Ce, Nd, Tl, and Bi) were nanosized single grains or aggregated grains and embedded in sulfate and organics. ● Particles containing As, and Cd were distributed homogenously within the organic particles in more than half of the cases. [ABSTRACT FROM AUTHOR]

Input of dust to the ocean via the atmosphere is one of the key processes driving the development of marine ecosystems. It is usually estimated with dust concentration and deposition velocity on the assumption that particles settling to the marine surface are similar in composition to those in the air. In this study, we compared suspended and dry deposited dust particles which were collected at a seaside site on the southwestern Japan coast in two Asian dust episodes. Results show that particles mixed with sea salt and sulfate occupied 47–67% of the suspended dust particles while the percentage was 15–26% for the deposited particles. Sulfur and sodium contents in the deposited particles were apparently less than in the suspended particles. The mode size of the suspended ones, 2–3 μm, was a little smaller than that of the dry deposited ones, 3–5 μm. However, after being weighted by deposition velocity, it was similar to the latter one. These results support particle size as the key factor in determining the dry deposition and indicate the difference of suspended and deposited dust particles in the mixture with sea salt and sulfate in the marine atmosphere. [ABSTRACT FROM AUTHOR]

Smoke aerosol emitted by large scale wildfires in the European part of Russia and Ukraine, was transported to Athens, Greece during August 2010 and detected at an urban background site. Measurements were conducted for physico-chemical characterization of the aged aerosol and included on-line monitoring of PM 10 and carbonaceous particles mass concentrations, as well as number size distributions and aerosol optical properties. In addition TSP filter samples were analyzed for major inorganic ions, while morphology and composition of particles was studied by individual particle analysis. Results supported the long-range transport of smoke plumes from Ukraine and Russia burning areas indicated by back trajectory analysis. An increase of 50% and 40% on average in organic (OC) and elemental carbon (EC) concentrations respectively, and more than 95% in carbonate carbon (CC) levels was observed for the biomass burning (BB) transport period of August with respect to the previous month of July. Mean 24-h OC/EC ratio was found in the range 3.2–8.5. Single scattering albedo (SSA) was also increased, indicating abundance of light scattering constituents and/or shift of size distributions towards larger particles. Increase in particle size was further supported by a decreasing trend in absorption Angström exponent (AAE). Ion analysis showed major contribution of secondary species (ammonium sulfate and nitrate) and soil components (Ca 2+ , Mg 2+ ). Non-sea salt K + exhibited very good correlation with secondary species, indicating the long-range transport of BB smoke as a possible common source. Individual particle analysis of the samples collected during BB-transport event in Athens revealed elevated number of soot externally mixed with fly ash Ca-rich particles. This result is in agreement with the increased OC and CC levels measured, thus pointing towards the main components comprising the aged BB aerosol microstructure. [ABSTRACT FROM AUTHOR]

Abstract: Atmospheric particles larger than 0.2μm were collected at the top of Mt. Tai (36.25°N, 117.10°E, 1534m a.s.l.) in eastern China in May 2008 during the passage of a strong cyclone. The particles were analyzed with electron microscopes and characterized by morphology, equivalent diameter and elemental composition. Soot particles with coating (coated soot particles) and those without apparent coating (naked soot particles) were predominant in the diameter range smaller than 0.6μm in all samples. The number–size distribution of the relative abundance of naked soot particles in the prefrontal air was similar to that in the postfrontal air and their size modes were around 0.2–0.3μm. However, the distribution of inclusions of coated soot particles showed a mode in the range of 0.1–0.3μm. The coating degree of coated soot particles, which was defined by the ratio of the diameter of inclusion to the diameter of particle body, showed a mode around 0.5 with the range of 0.3–0.6. These results indicate that the status of soot particles in the prefrontal and postfrontal air was similar although air pollution levels were dramatically different. In addition, the relative abundance of accumulation mode particles increased with the decrease of soot particles after the front passage. [Copyright &y& Elsevier]

Aerosol samples were collected during the scientific expedition to Mt. Bogda in July-August, 2009. The major inorganic ions (Na, NH $_{4}^{\,\,+}$, K, Mg, Ca, Cl, SO $_{4}^{\,\,2-}$, and NO $_{3}^{\,\,-}$) of the aerosols were determined by ion chromatography. SO $_{4}^{\,\,2-}$, NO $_{3}^{\,\,-}$, and Ca were the dominate ions, with the mean concentrations of 0.86, 0.56, and 0.28 $\upmu $g m, respectively. These mean ion concentrations were generally comparable with the background conditions in remote site of Xinjiang, while much lower than those in Ürümqi. Morphology and elemental compositions of 1,500 particles were determined by field emission scanning electron microscopy equipped with an energy dispersive X-ray spectrometer. Based on the morphology and elemental compositions, particles were classed into four major groups: soot (15.1%), fly ash (4.7%), mineral particles (78.9%), and little other matters (0.8% Fe-rich particles and 0.5% unrecognized particles). Presence of soot and fly ash particles indicated the influence of anthropogenic pollutions, while abundance mineral particles suggested that natural processes were the primary source of aerosols over this region, coinciding with the ionic analysis. Backward air mass trajectory analysis suggested that Ürümqi may contribute some anthropogenic pollution to this region, while the arid and semi-arid regions of Central Asia were the primary source. [ABSTRACT FROM AUTHOR]

Consumption of coal is increasing as an alternative for petroleum. During the process, coal fly ash particles are produced and are disposed as an industrial waste. Coal ash contains toxic heavy metals, which leads to a concern about the possibility of leakage into environment. The spatial distribution and chemical form as well as elemental concentration of the toxic elements in the particles are important factors in assessing the leakage into the environment. In this study, we analyzed individual coal fly ash particles with 1 µm spatial resolution by using the simultaneous micro-PIXE/RBS/off-axis STIM system at Tohoku University. Eighty fly ash particles were analyzed. The particles are mainly composed of O, Si and Al and estimated as dioxide. Hydrogen and carbon are not observed in these particles. V, Zn, Sr, Cu, Ni, Mn, Cr and As are contained in the particles. The content of each element is quite different in each particle. These elements are distributed homogeneously. As an exception, Al, Ca, Fe, Zn, As and Zr are distributed on the surface of the particle which might be related to the combustion process. [ABSTRACT FROM AUTHOR]

Aerosol samples were collected during winter fog and nonfog episodes in Beijing. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were applied to study morphologies, sizes, and compositions of aerosol particles. TEM observation indicates that most mineral particles collected in fog episode are scavenged in fog droplets. Number–size distributions of mineral particles collected in fog and nonfog episodes show two main peaks at the ranges of 0.1–0.3 and 1–2.5 μm, respectively. Based on their major compositions, mineral particles mainly include Si-rich, Ca-rich, and S-rich. Average S/Ca ratio of mineral particles collected in fog episode is 6.11, being eight times higher than that in nonfog episodes. Development mechanism of individual mineral particles in fog droplets is proposed. It is suggested that mineral particles with abundant alkaline components (e.g., “Ca-rich” particles) occurred in air should alleviate acidic degree of fog and contribute to complexity of fog droplets in Beijing. [ABSTRACT FROM AUTHOR]

Atmospheric aerosols were collected during the scientific expedition to Mt. Qomolangma (Everest) in May–June, 2005. The elemental concentrations of the aerosols were determined by inductively coupled plasma mass spectrometry. This yielded data for the concentration of 14 elements: Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, and Pb. The mean elemental concentrations were generally comparable with those from central Asia and the Arctic, while much higher than those from Antarctic. Size, morphology, and chemical composition of 900 individual aerosol particles were determined by scanning electron microscopy and energy-dispersive X-ray microanalysis. Based on morphology and elemental composition, the particles were clustered into eight groups: soot (8%), tar ball (3%), alumosilicates/silica (55%), calcium sulfate (16%), Ca/Mg carbonate (2%), Fe/Ti-rich particles (3%), Pb-rich particles (1%), and biological particles (12%). The sampling site, located at 6,520 m in the Himalayas, is particularly remote and located at high altitude. Nonetheless, high aerosol enrichment factors for copper, chromium, lead, nickel, vanadium, and zinc all suggest the influence of long-range transported pollution, while enrichment in calcium and the presence of alumino-silicates in individual particle analyses indicates a distinct mineral dust influence. The backward air mass trajectories showed that the northwestern part of India may contribute to the atmospheric aerosol in the central high Himalayas. [ABSTRACT FROM AUTHOR]

Taiyuan, the capital of Shanxi province, China, is one of the most polluted cities in the world. To characterize the ambient particulate pollution, samples of particulates with aerodynamic diameter less than 10 µm (PM10) were collected during a 6-day campaign. Individual particles were analyzed by Scanning Electron Microscope with Energy-Dispersive Spectrometer (SEM-EDS) to determine their chemical composition. Meanwhile, photomicrographs were obtained from SEM to aid in particles’ source identification. The lumped data from SEM-EDS were subjected to hierarchical cluster analysis (HCA) to sort out particle types chemically. HCA combined with SEM photomicrographs allowed us to identify 20 different particle types, namely (in order of particle frequency), soil/fly ash particles, coal-burning, sulfur-rich, and iron-rich particles, gypsum, syngenite, quartz, cement, silicon sulfide, siliconferro alloy, calcium-rich particles, ferrochromium alloy, ammonium sulfate and chloride, iron-zinc, ammonium chloride, molybdenum-rich, potassium sulfate, dolomite, lead sulfate, and copper-rich particles. Their possible origins and pathways are suggested. The majority of the particles seem to originate from coal combustion, which conforms to Taiyuan’s industrial structure. [ABSTRACT FROM AUTHOR]

Characteristics of individual particles from a super dust storm (DS) on 20 March 2002, and those of non dust storm aerosols for Beijing (NDS) and Duolun (DL) (a desert area) are determined using a variety of methods. In China, typically the source of aerosols in dust storms is thought to be deserts with aluminosilicates being the main constituent particles; however, this does not reflect a complete analysis with our evidence indicating potential alternate dust sources along the storm's transport path. Individual particle analysis of aerosols collected from a super dust storm on 20 March 2002 in Beijing shows that among all the 14 elements measured, only S and Cl have remarkable positive correlation. 82.5% of all particles measured contained both S and Cl, and the relative mass percentage of S and C1 in these particles is much higher than the average of all particles. 62.0% of all particles contained S, Cl, and Na, in which the concentration of Na is 1.4 times higher than average. PMF (Positive Matrix Factorization) analysis indicates that NaCl and Na2SO4 are major components of these particles with S and C1 showing significant positive correlation. Moreover, SO42- and Cl- also show significant positive correlation in bulk aerosol analysis. XPS (X-ray Photoelectron Spectroscopy) analysis of the surface of aerosols demonstrates that concentrations of Na and S on particles from the dust storm are higher than those from non-dust storm particles in Beijing and also for particles from. It is very likely that particles enriched with S, Cl, and Na is from the surface soils of dried salt-lakes and saline soils enriched with chloride and sulfate. This evidence demonstrates that besides deserts, surface soils from dry salt-lakes and saline soils of arid and semi-arid areas are also sources of particulates in dust storms over Beijing. [ABSTRACT FROM AUTHOR]

To set up a sampling and analysis strategy for particulate matter (PM) based on the time periods used in international standards is often inadequate for assessing the impact of day/night cycles or episodic emissions on urban air quality. To obtain a detailed physico–chemical characterization of urban PM when concentrations exceed the regulatory thresholds, a new rotary cascade impactor named the Time-Resolved Atmospheric Particle Sampler (TRAPS) was designed and tested for coarse and fine particle sampling. The TRAPS implementation, coupled with Optical Particle Counter measurements, provides time-resolved samples that can be analyzed by a wide range of single-particle analysis techniques. The TRAPS theoretical design was verified experimentally. Experimental cut-off diameters of 1.32 and 0.13 µm, respectively, for coarse and fine stages, were found in good agreement with theoretical values. Additionally, good trace separation, preventing inter-sample contamination, was evidenced by Scanning Electron Microscopy (SEM). The homogeneous distribution of particles of different types over a trace was also verified. As a case study, automated SEM-EDX analysis of 2500 particles, collected during two pollution peaks of a transient PM2.5 pollution event, revealed that individual particles' chemical composition was influenced by local sources during the first pollution peak, and mainly transported during the second peak. [ABSTRACT FROM AUTHOR]

Abstract: Airborne aerosol collections were performed over Wakasa bay (36°00′N, 135°30′E) in March and Kumano open sea (34°00′N, 136°50′E) and Seto (35°10′N, 137°10′E) in July 2001 at altitudes between 1.0 and 5.8 km. The particles were individually analyzed using transmission electron microscopy (TEM). Relatively large mineral-dust (mostly clay) particles were abundant in the March samples. They also dominated in July in the mid-troposphere higher than 4 km altitude, whereas sea salt and ammonium sulfate were more abundant at lower altitudes. Ca-coated grid samples show many traces of aqueous sulfate droplets. The proportions of former sulfate droplets to the total collected particles apparently increased with increasing relative humidity at the time of sampling. TEM analysis revealed that a significant fraction of these former droplets enclose mineral-dust particles as well as sea salt, soot, and fly ash. Some enclose mixtures of mineral-dust, sea-salt, soot, and fly ash particles. The results provide evidence that mineral dust from the Asian continent could acquire coatings of sulfate while being transported in the free troposphere. The mineral-dust particles probably acquired the sulfate coatings either through heterogeneous uptake of gaseous SO2 and subsequent oxidation or through coagulation with cloud or fog droplets. The presence of the mixed particles in sulfate droplets also indicates that aggregation of particles of different origins occurred through cloud processing. Such sulfate-coated dust particles would affect cloud formation, precipitation, and chemistry of the free troposphere. [Copyright &y& Elsevier]

Abstract: The sources and character of individual metal and metalloid particles from atmospheric dry depositions in Kobe, Japan were investigated. Japan faces long-range pollutant transportation from northeastern Asia during winter and spring. Information regarding their properties and sources is useful for evaluating their affects on the environment and human health. Individual metal and metalloid particles that were collected for every 24h on the plate, which was designed to reduce a local turbulence, were characterized for their composition, diameter, and deposition fluxes using a field emission scanning electron microscope with an energy dispersive X-ray spectrometer. Approximately 3000 metal and metalloid particles were classified into 14 types based on their composition and further classified into four groups based on their distribution patterns. They are (A) Fe–O, Fe–Ba–Sb–Cu–S–Ti–O, Fe–Zn–O, Zn–O, Ni–O, and Mn–Fe–O; (B) Cu–Zn–O and Cu–Sn–O; (C) Pb–O, Sn–Sb–O, and Ag–O; (D) Pb–Zn–Cl–Si–S–O and Bi–Cl–O. From these data, this study suggests their sources as the Asian continent (Group A), local source (Group B), multiple sources (Group C), and incineration process (Group D). This study shows (1) the sources and character of individual metal and metalloid particles from short-term atmospheric depositions in Kobe, Japan and (2) application of individual particle analysis for atmospheric depositions. [Copyright &y& Elsevier]

Abstract: Dusts collected on air filters at a Pb–Zn refinery located in northern France were sampled in 1997, 1999 and 2002. The low temporal variability in major elements (Pb, Zn and S) abundances suggested chemical composition of particulate emissions was stable over time. In July 2001 and March 2002, atmospheric aerosols were sampled in the vicinity of the Pb–Zn refinery upwind and downwind from the smelters. Bulk concentrations of major elements (Al, Fe, Pb and Zn) and hydrosoluble ions (Na+, NH4 +, Mg2+, K+, Ca2+, Cl– NO3 – and SO4 2–) were, respectively, determined by atomic absorption spectrometry and ion chromatography. Elemental and molecular individual particle analyses were, respectively, performed by automated SEM–EDX and Raman microspectrometry. Continental air masses (campaign 2001) were characterized by low Na+ and high SO4 2–, NO3 – and NH4 + contents upwind from the smelters. Individual particle analysis of Pb- and Zn-rich airborne particles collected downwind from the refinery indicated elemental associations and molecular speciation were similar to those obtained at the emission: Pb compounds were mainly identified as oxides, sulfates and oxy-sulfates whereas Zn compounds were identified as sulfides. Marine air masses (campaign 2002) were characterized by high Na+ contents upwind from the smelters. Individual particle analysis of Pb- and Zn-rich particles collected downwind from the refinery pointed out a systematic association with Na, not emitted by the refinery, suggesting internal mixing of marine aerosols with heavy-metals dusts emitted by the refinery. Such fast evolution of airborne particles chemical composition in the vicinity of the refinery was further proven by SEM–EDX and Raman microspectrometry mappings showing physical evolution by aggregation or coagulation of Zn- and Pb-rich particles with aged sea-salts. [Copyright &y& Elsevier]

Inorganic particles in the upper waters of the 11 Finger Lakes of New York are morphometrically and elementally characterized by individual particle analysis conducted with scanning electron microscopy interfaced with automated image and X-ray analyses (IPA/SAX). Coupled measurements of Secchi disk transparency (SD), the attenuation coefficient for downwelling irradiance ( K d), the beam attenuation coefficient at 660 nm, and turbidity ( T n) were made to support evaluation of the importance of non-living, inorganic particles (inorganic tripton) in regulating these optical features of water quality. Wide differences in levels of inorganic tripton, represented in terms of particle projected area per unit volume (PAV in), and the optical measures are reported for these lakes. However, generally similar size distributions are observed for the inorganic tripton for the lakes. Terrigenous suspensoids, in the form of clay minerals, dominated the inorganic tripton particle assemblage of nine lakes, while CaCO3, formed autochthonously, dominated in the other two and was a noteworthy contributor in four others. PAV in is demonstrated to be an important regulator of the optical properties of these lakes, performing substantially better than chlorophyll in predicting SD, and T n, and interlake differences in these optical measures. [ABSTRACT FROM AUTHOR]

Abstract: Aerosol samples were collected in the Atlantic marine boundary layer between the English Channel and Antarctica during November–December 1999. The composition of coarse (aerodynamic diameter ∼1–3 μm) individual aerosol particles was studied using the SEM/EDX method. The major particle types observed were fresh sea salt, sea-salt particles reacted partly or totally with sulphuric acid or nitric acid, Mg-sulphate, Ca-sulphate, mixed aluminosilicates and sea salt, aluminosilicates, Ca-rich particles and Fe-rich particles. The relative fractions of sea-salt particles with moderate or strong Cl depletion were high near the coasts of Europe (65–74%) and Northern Africa (44–87%), low far from the coast of Western Africa (10–20%) and very low in remote sea areas between Africa and Antarctica (∼1%). The Cl depletion was strongest when air masses arrived from the direction of anthropogenic pollution sources. The fractions of Mg-sulphate particles were high (18–25%) in 2 samples near Europe. The Mg-sulphate particles were probably formed as a result of fractional recrystallization of sea-salt particles in which Cl was substituted by sulphate. It remained unclear whether these particles were formed in the atmosphere or during and after sampling. The relative fractions of particles from continental sources were quite low (10–15%) near Europe, very high (25–78%) near the coast of Northwestern Africa and very low in the remote sea areas (0–2%). Most of the continental particles were aluminosilicates and some of them were internally mixed with sea salt. Near the coast of Northwestern Africa, the main source of aluminosilicates was Saharan dust, and near the Gulf of Guinea, emissions from biomass burning were also mixed with aluminosilicates and sea salt. [Copyright &y& Elsevier]

Abstract: PM10 samples were collected during 5 days in Guiyang, China in July 2003. A total of about 2300 particles was analyzed by an automated Scanning Electron Microscope with Energy-Dispersive Spectrometer (SEM–EDS). Hierarchical cluster analysis (HCA) was used to identify different particle types that occurred in the aerosol. Seventeen particle types were identified and presented in the order of decreasing number abundance as: silicomanganese slag, soil and fly ash, coal burning, silicomanganese, quartz, syngenite, S-bearing iron, calcium rich, gypsum, sphalerite, dolomite, iron, alloy, lead sulfate, zinc rich, sulfur-rich particles and aluminum manufacturing dust. The majority of the particles in the studied size range are of anthropogenic origin, especially from metallurgical industry. The study illustrates the complexity of particle pollution in air of an industrial Chinese city and the results should be useful in planning mitigation measures. [Copyright &y& Elsevier]

Abstract: Capillary electrophoretic analysis of individual submicrometer size particles has been previously done using custom-built instruments. Despite that these instruments provide an excellent signal-to-noise ratio for individual particle detection, they are not capable of performing automated analyses of particles. Here we report the use of a commercial Beckman P/ACE MDQ capillary electrophoresis (CE) instrument with on-column laser-induced fluorescence (LIF) detection for the automated analysis of individual particles. The CE instrument was modified with an external I/O board that allowed for faster data acquisition rates (e.g. 100Hz) than those available with the standard instrument settings (e.g. 4Hz). A series of eight hydrodynamic injections expected to contain 32±6 particles, each followed by an electrophoretic separation at −300Vcm−1 with data acquired at 100Hz, showed 28±5 peaks corresponding to 31.9 particles as predicted by the statistical overlap theory. In contrast, a similar series of hydrodynamic injections followed by data acquisition at 4Hz revealed only 8±3 peaks suggesting that the modified system is needed for individual particle analysis. Comparison of electropherograms obtained at both data acquisition rates also indicate: (i) similar migration time ranges; (ii) lower variation in the fluorescence intensity of individual peaks for 100Hz; and (iii) a better signal-to-noise ratio for 4Hz raw data. S/N improved for 100Hz when data were smoothed with a binomial filter but did not reach the S/N values previously reported for post-column LIF detection. The proof-of-principle of automated analysis of individual particles using a commercially available CE system described here opens exciting possibilities for those interested in the study and analyses of organelles, liposomes, and nanoparticles. [Copyright &y& Elsevier]

Individual particle analysis (IPA) by scanning electron microscopy663 interfaced with automated image and X-ray analyses was used to characterize inorganic particles in five reservoirs and four tributaries located within the Catskill and Delaware systems of the New York City water supply. Individual particle analysis provides combined elemental and morphologic characterizations. Results are presented in terms of particle projected area per unit volume (PAV), consistent with optical impacts, and partitioned into seven generic particle types according to composition. Minerals of terrigenous origins, particularly clay minerals, dominated the inorganic particle populations of all the study systems except one downstream reservoir. Higher PAV levels were observed in the Catskill system. Particle dynamics represented by PAV were driven primarily by runoff, while the reservoirs were also greatly influenced by the timing of sediment resuspension promoted by drawdown of the surface and fall mixing. The benefit of the serial configuration of the reservoirs in decreasing inorganic particles with progression downstream towards the city is demonstrated. The patterns in PAV levels among the study systems generally tracked those of more common metrics of impacts of suspensoids, including mass concentrations of suspended solids, turbidity, and Secchi disc transparency. [ABSTRACT FROM AUTHOR]

Biomass burning is an important primary and secondary source of aerosol particles. The presence of carbonaceous particles in the respirable size range makes the study of this fraction important in view of possible health and climatic effects. The annual burning of sugar cane plantations causes emission of huge amounts of pyrogenic particles. Aerosol samples were collected in Araraquara city, São Paulo state, Brazil, during the harvest season for fine and coarse particles and bulk; they were analysed by electron-probe microanalysis, including facilities for low-Z element determination (low-Z EPMA) and by energy-dispersive X-ray fluorescence (EDXRF), in order to investigate the elemental composition of individual particles and bulk samples, respectively. Numerical analysis of the EPMA results by hierarchical clustering shows high contributions of carbonaceous particles that can be distinguished mainly in two different types: biogenic and carbon-rich. Additionally, two significant contributions of aluminosilicate particles were identified: as rather pure aluminosilicates or mixed with carbonaceous species. The EDXRF results are compatible with those of aerosol particles in Amazon, which is nowadays one of the main sources of biogenic particles in the world. [ABSTRACT FROM AUTHOR]

The hygroscopic behaviour of NaCl, (NH4)2SO4, Na2SO4 and NH4NO3 particles in the size range of 0.1–20 μm was studied by environmental scanning electron microscopy (ESEM). This technique allows the in-situ observation of individual aerosol particles while changing the temperature and/or relative humidity (RH) in the sample chamber. The hygroscopic behaviour of these particles (e.g., deliquescence, adsorption of water on the particle surface) becomes directly observable with a lateral resolution of the order of 8–15 nm. The deliquescence relative humidities (DRH) of the different salts, the temperature dependence of the DRH for NH4NO3, and the growth factors (at increasing relative humidities) for NaCl were determined. Generally, a good agreement between the values obtained by ESEM and those found in literature was achieved. However, the DRH of NaCl determined by ESEM is systematically higher (approximately 2%, absolute) than the values obtained by other techniques, which can be explained by the observed strong absorption of water onto the crystal surface prior to droplet formation. The efflorescence behaviour of individual particles can be studied only qualitatively due to influences of the sample substrate. Furthermore, it is demonstrated that the activation of soot can be studied at high resolution by ESEM. [Copyright &y& Elsevier]

The combination of single-particle analysis using thin-window EPMA and a reverse Monte Carlo quantification procedure has been proven to provide semi-quantitative elemental concentrations, including light elements. The capabilities of the method are demonstrated through three different environmental applications in Hungary. Lake Balaton is the largest lake in central Europe. It is suspected that the atmosphere is an important source of environmental deterioration of the Lake, relative to the pollutant supply by rivers and direct discharges. Thin-window EPMA results of around 25,000 individual particles indicated that the composition of the aerosol did not show characteristic seasonal variation, it was more correlated to the daily meteorological circumstances. A serious heavy metal pollution of the river Tisza occurred on 10 March 2000, from a mine-dumping site in Romania. Sediment samples were taken from the main riverbed at six sites, on 16 March 2000. In some of the samples, pyrite type particles were observed in high abundance, revealing their dumping-site origin. Biomass burning for energy production has been increased recently, mostly in households and for space heating. Fly-ash and bottom-ash samples were collected at a 600 kW heating plant at Sződliget during standard winter operation. Most particles contained over 65% of unburned organic substance. The concentrations of major elements were obtained for each individual particle using thin-window EPMA, providing accurate matrix composition for further μ-XRF investigations of the trace element composition. [ABSTRACT FROM AUTHOR]

Beijing is one of the most important Chinese megacities with extremely serious air pollution problems and human health impacts. In response to the air pollution the central and municipal governments of China have implemented a series of actions; one of which is the "Action Plan for Comprehensive Prevention and Control of Autumn and Winter Air Pollution in Beijing-Tianjin-Hebei and Surrounding Areas 2017–2018" (the Action Plan) issued in 2017. The morphology, composition and mixing state of individual particles collected after the Action Plan was implemented were analyzed by high resolution-transmission electron microscopy coupled with an energy-dispersive X-ray spectrometer (TEM-EDX). The relative percentages of different individual particle types and the main sources of the particulate pollution before and after the Action Plan were compared. The results showed that sulfur was most frequently detected in the individual particles, and the particle types were mainly composed of soot aggregates, mineral particles, organic particles, metal particles, coal fly ashes, sulfate particles, and mixture particles. The mixture and sulfate particles dominated in the autumn samples, both for the haze and non-haze days. In winter the mineral and mixture particles dominated in samples for the non-haze days, while mixture particles and sulfate dominated in the samples for the haze days. The mixture particles in autumn were mainly the soot aggregates internally mixed with sulfate (S-soot type), while the mixture particles in winter were mainly the S-soot type and the mineral particles internally mixed with sulfate (S-mineral type). After the Action Plan, the relative percentages of sulfate particles, organic particles, and soot aggregates increased, while the relative percentages of mineral particles, metal particles and fly ashes decreased. The contribution from coal-fired sources was reduced significantly as evidenced by the decrease in the fly ash particles. The vehicle emissions and secondary reaction of particulate matter became the main sources of atmospheric particulate matters as evidenced by increase in sulfate particles, organic particles, and soot aggregates. The results presented in this study will assist in other plans to improve air quality and human health in megacities around the world. • Individual airborne particles collected in Beijing after the Action Plan in 2017 were investigated. • Soot aggregates, organic, metal, mineral, coal fly ash, sulfate, and mixture particles were identified. • Sulfate particles and sulfate-mixed primary particles were dominant in Beijing air. • The relative percentages of sulfate, organic and soot aggregates increased after the Action Plan. • The contributions of vehicle emission and secondary reactions increased. [ABSTRACT FROM AUTHOR]

The characterisation of mineral dust at emission sources is essential for quantifying the wider-scale environmental impacts dust has, as well as improving its incorporation in modelling. Methods of sampling sediments at these source areas for the purposes of dust characterisation are varied and can produce different representations of emitted dust. This study systematically compared dust characterisations from three established approaches for estimating dust emission potential, namely: Big Spring Number Eight (BSNE) traps, a Portable In-situ Wind Erosion Laboratory (PI-SWERL) wind tunnel, and bulk surface sampling, at a known Namib Desert dust source. Individual particle analysis by auto-SEM (QEMSCAN) allowed comparison of size, shape, mineralogy and elemental composition at micrometre-scale for samples from the three approaches. BSNE samples consisted of a lower proportion of fine sediment (<20 µm particle diameter) than PI-SWERL-derived samples, with this performance possibly influenced by atmospheric humidity. In comparison, PI-SWERL characterised the dust with relatively fewer particles between 63 and 100 µm, a fraction that was more evident in both the BSNE-derived and surface sediments. The reduced representation of this coarser fraction resulted in appreciable differences in particle shape and mineralogic characteristics compared to BSNE and surface-derived samples. The different representations by the three methods return variable dust characteristics at source across fundamental properties of particle size, shape and mineralogy. Awareness of the different representations of dust caused by sampling technique remains essential for the appropriate physical and geochemical characterisation of aeolian dust and highlights how standardised techniques are important for meaningful comparisons, while methods to achieve accurate characterisation remain a priority for the discipline. [ABSTRACT FROM AUTHOR]

Carbonaceous aerosol particles emitted from biomass burning (BB) have a large impact on the global climate. In particular, tarball particles (TBs), which are spherical organic aerosol particles, account for a large proportion of aerosol particles from BB. In this study, we collected aerosol particles over the western North Pacific and analyzed them using transmission electron microscopy with energy-dispersive X-ray spectroscopy (TEM-EDX) to reveal their shape and composition. We detected TBs and organic carbon particles originating from Siberian forest fires. To the best of our knowledge, this is the first case in which a large number of TBs have been found over the Pacific Ocean far from the BB source. The spherical shapes of the TBs were maintained even after long-range transport. In addition, our individual analysis of TBs showed that the size and composition of TBs differ depending on the air mass origin. The occurrence and microphysical properties of TBs are important to accurately evaluate the impact of TBs on climate. Our results imply that TBs can be transported to the Arctic and have an influence on radiative forcing over the ocean and in the Arctic. [ABSTRACT FROM AUTHOR]