Individual Particle Analysis Research Articles

Spatial and Temporal Variations of Atmospheric Aerosol in Osaka

It is well known that the aerosol distribution in Asia is complex due to both the increasing emissions of the anthropogenic aerosols associated with economic growth and the behavior of natural dusts. Therefore, detailed observations of atmospheric particles in Asian urban cities are important. In this work, we focus on the spatial and temporal variations of atmospheric particles around Higashi-Osaka in Japan. Higashi-Osaka is located in the eastern part of Osaka, the second-largest city in Japan, and is famous for small- and medium-sized manufacturing enterprises. For this study, we placed various ground measurement devices around the Higashi-Osaka campus of Kinki University including a Cimel sunphotometer supported by NASA/AERONET (Aerosol robotics network), suspended particulate matter (SPM) sampler and LIDAR (light detection and ranging). Individual particle analyses with a SEM (scanning electron microscope)/EDX (energy-dispersive X-ray analyzer) show the temporal variations of particle properties, such as size, shape and components, during a dust event on 21 March 2010. The simultaneous measurement using a portable sun photometer with AERONET was conducted from April to November 2011. A comparison of the data at each site and the combination of the observed LIDAR data and model simulations indicate the difference in the transportation processes between dust and anthropogenic particles. We suppose this difference is attributed to the differences in the vertical aerosol profiles, where one aerosol is transported over Mount Ikoma and the other is blocked by it.

Composition and Morphology of Particle Emissions from in-use Aircraft during Takeoff and Landing

In order to provide realistic data for air pollution inventories and source apportionment at airports, the morphology and composition of ultrafine particles (UFP) in aircraft engine exhaust were measured and characterized. For this purpose, two independent measurement techniques were employed to collect emissions during normal takeoff and landing operations at Brisbane Airport, Australia. PM1 emissions in the airfield were collected on filters and analyzed using the particle-induced X-ray emission (PIXE) technique. Morphological and compositional analyses of individual ultrafine particles in aircraft plumes were performed on silicon nitride membrane grids using transmission electron microscopy (TEM) combined with energy-dispersive X-ray microanalysis (EDX). TEM results showed that the deposited particles were in the range of 5-100 nm in diameter, had semisolid spherical shapes and were dominant in the nucleation mode (18-20 nm). The EDX analysis showed the main elements in the nucleation particles were C, O, S, and Cl. The PIXE analysis of the airfield samples was generally in agreement with the EDX in detecting S, Cl, K, Fe, and Si in the particles. The results of this study provide important scientific information on the toxicity of aircraft exhaust and their impact on local air quality.

Particle Sampling by TEM Grid Filtration

Transmission electron microscopy (TEM) coupled with energy-dispersive X-ray (EDX) offers a very comprehensive tool for individual particle analysis allowing the determination of size, morphology, specific surface, and elemental composition. This information is needed in aerosol studies, especially in the field of nanomaterials. However, observations with TEM require a controlled sampling on an adapted analysis support, namely TEM grid. Techniques allowing sampling on TEM grids are of great interest to aerosol analysis. Indeed, sample preparation is not required, thereby gaining time and avoiding a risk for the sample to be altered. The present study evaluates the efficiency of a new particle collection technique based on filtration through one class of TEM-dedicated supports, namely TEM porous grids. Two types of porous grids, considered as the best on the market for this application, have been put to the test: the 'Quantifoil' type porous grid, which has a regular structure, and the 'Holey' type (Agar Scientific, Stansted, Essex, England). A filter holder has been developed specifically for this application, the MPS (Mini-Particle Sampler , Ecomesure, Janvry, France). Experimental tests have been carried out with a flow rate of 0.3 L min-1. They show that the collection is operational in the 5-nm to 150-nm size range, with a minimum efficiency of 15-18% around 30 nm. Simulation confirms these results and shows an increased efficiency even below 5 nm and beyond 150 nm. The filter holder MPS designed in this study is a low-cost, portable, versatile, and easy-to-use tool.

Aerosol dynamics upon Terni basin (Central Italy): results of integrated vertical profile measurements and electron microscopy analyses

In this work, aerosol size distribution measurements along with individual particle analyses were performed along the vertical profile in the atmosphere, to shed some light on the dynamics of evolution of aerosol properties upon a basin valley. The case study is the Terni basin, one of the most polluted urban and industrial sites in central Italy. Aerosol vertical profile measurements were performed using a helium-filled tethered balloon equipped with an optical particle counter (OPC), a miniaturized cascade impactor with particle collection filter, and a portable meteorological station. Combined OPC number size measurements and single particle analyses by scanning electron microscopy were employed to reconstruct the pattern and evolution of aerosol properties over the basin. Moreover, the CHIMERE chemistry-transport model was applied over a selected computing domain to obtain a general overview of the driving forces of the aerosol dynamics. Scanning electron microscopy methods along with chemical transport modeling revealed distinct distributions of number, size and geochemical properties of different particles classes in the aerosols. These reflect distinct behaviours and spatial/temporal evolution of the constituent particles, along with the common occurrence of dust inputs from regional to long range sources (e.g., Saharan dust inputs). All these features have to be taken into consideration when approaching the modeling of atmospheric processes, particularly in basin valleys located in Central and Southern Italy where the influence of Saharan dust outbreaks is more pronounced.

Scanning Transmission Electron Microscopy Analysis of Diesel Soot Particles for Source Attribution

Scanning transmission electron microscopy (STEM) coupled with energy dispersive x-ray analysis (EDX) has been used to characterize the elemental composition of diesel soot samples. The STEM employed in this investigation is the Vacuum Generators Microscope HB603, with a microanalytical resolution approaching 1 nm, allowing the analysis of individual soot particles and aggregates. Quantification of the EDX spectra is accomplished after background and absorption corrections. This information can then be used to pinpoint the fuels and combustion process from which the soot originated. Six diesel soots were analyzed in this study including three from a U.S. Bureau of Mines diesel test engine, two from a West Virginia University diesel test engine, and one from an Orion diesel bus engine. This research showed that soot impurities were found throughout the aggregates, and that only one or two soot particles were necessary to obtain a chemical fingerprint. Some of these elements may be traced to the fuel and lubricant. Other elements were components of the engine itself that combined with the soot particulates during the combustion process. The concept of using a ‘Truth Table’ for the purpose of source attribution is also introduced.

Characterizations and modeling of turbidity in a water supply reservoir following an extreme runoff event

The findings from an integrated program of short- and long-term monitoring, individual particle analyses (IPA), and mechanistic modeling to characterize and simulate the turbidity (Tn) effects of an extreme runoff event (2011) on a water supply reservoir were documented. A robotic profiling platform and rapid profiling instrumentation resolved turbidity and temperature (T) patterns in time and space in the reservoir. Metalimnetic enrichment in Tn following the event was reported and attributed to the entry of turbid stream water as density currents, or plunging inflows. The diminishment of high Tn levels following the event was well represented by a first-order loss rate of about 0.023 d−1. The highest Tn levels were avoided in water withdrawn for the water supply following the event by selection of vertical intake alternatives, although Tn values in the withdrawal remained distinctly above typical baseline conditions for nearly 2 months. Based on IPA, the Tn-causing particles were mostly clay minerals in the 1–20 μm size range. The operation of sorting processes determining settling losses from the minerogenic particle population, according to their size and shape, following the runoff event was resolved. The set-up and testing of a mechanistic Tn model, composed of 2 submodels, a 2-dimensional hydrothermal/transport submodel, and a Tn kinetics submodel, is described. The hydrothermal/transport submodel was tested separately and performed well in simulating the dynamics of the reservoir’s stratification regime and the entry of the dense streams as plunging inflows during the extreme runoff event. The overall Tn model needed to represent the loss processes of both settling and coagulation to perform well in simulating the in-reservoir and withdrawal Tn patterns following the runoff event.

環境試料中の単一核物質含有微粒子の分析

環境試料中の単一核物質含有微粒子の分析

The use of solution nebulization ICP-MS combined with particle screening and micro-sampling for analysis of individual uranium-bearing particles

Solution nebulization inductively coupled plasma mass spectrometry (ICP-MS) was applied to the analysis of uranium isotope abundance ratios in individual particles. Particle screening was carried out before ICP-MS analysis using two different techniques: irradiation with thermal neutrons and fission track observation (so-called “fission track technique”) on the one hand and automated particle measurement (APM) in secondary ion mass spectrometry (SIMS) on the other hand. Uranium-bearing particles localized by the screening techniques were sampled individually by micro-sampling devices inside a scanning electron microscope and deposited on clean silicon wafers for subsequent chemical dissolution and ICP-MS measurement. The micro-sampling enables us to avoid polyatomic ion interferences and measure some uranium-bearing particles at the same time in isotopic analysis. Using both methods, particles from certified reference materials and a real-life sample taken at a nuclear facility were measured to evaluate the performance of the methods. Using ICP-MS combined with the fission track technique, the uranium isotope abundance ratios were successfully determined for individual particles with diameters ranging from 1.2 to 2.4 μm in a certified reference material (NBL CRM U100). The analysis of the real-life sample using ICP-MS combined with the fission track technique gave 235U/238U isotope abundance ratios between 0.0246 and 0.0376. When APM was used as the particle screening method for the real-life sample, 235U/238U isotope abundance ratios ranging from 0.0259 to 0.0432 were obtained. These values were higher than those obtained by a well-established method for particle analysis (SIMS). From these results, it can be concluded that both techniques allow selection and analysis of the uranium particles with the highest 235U abundance, which is the most important for nuclear safeguards.

Light scattering and Secchi depth in an oligotrophic lake: Insights from an individual particle analysis technique

Light-scattering attributes of particles of the upper waters of oligotrophic Skaneateles Lake, New York, were characterized monthly for the spring - fall interval of 2 years with scanning electron microscopy interfaced with automated image and X-ray analyses (SAX). SAX results were used to make forward estimates of the particulate scattering coefficients associated with 2 components (bx) of the overall particle population, minerogenic particles (bm) and diatoms (bdi), through Mie theory calculations. Estimates of the third component, scattering by organic particles other than diatoms (bo/nd), were calculated as the residual of bulk measurements of the particulate scattering coefficient (bp) and the summation of bm and bdi. Regulation of Secchi depth (SD) in the lake by bp was documented, in the form of a strong (R2 = 0.73) linear SD-1 - bp relationship. Variations in the summation (bm + bdi) explained 66% of the dynamics of bp and 56% for SD-1. A 2-component partitioning of bp that incorporates the SAX-Mie-based values of bm, and estimates of the contribution of all organic particulates with an empirical chlorophyll-a-based bio-optical model, failed to predict the bp dynamics but closed well on average for the entire study period. The SD-1 - bp relationship and the reported partitioning of bp were used to predict: (1) changes in bx from the study conditions that are consistent with a robust range of historic observations of SD, and (2) scenarios of management interest of levels of SD expected from hypothetical changes in bx.

Synthesis of Stable Ligand-free Gold–Palladium Nanoparticles Using a Simple Excess Anion Method

We report a convenient excess anion modification and post-reduction step to the impregnation method which permits the reproducible preparation of supported bimetallic AuPd nanoparticles having a tight particle size distribution comparable to that found for sol-immobilization materials but without the complication of ligands adsorbed on the particle surface. The advantageous features of the modified impregnation materials compared to those made by conventional impregnation include a smaller average particle size, an optimized random alloy composition, and improved compositional uniformity from particle-to-particle resulting in higher activity and stability compared to the catalysts prepared using both conventional impregnation and sol immobilization methods. Detailed STEM combined with EDX analyses of individual particles have revealed that an increase in anion concentration increases the gold content of individual particles in the resultant catalyst, thus providing a method to control/tune the composition of the nanoalloy particles. The improved activity and stability characteristics of these new catalysts are demonstrated using (i) the direct synthesis of hydrogen peroxide and (ii) the solvent-free aerobic oxidation of benzyl alcohol as case studies.

Red‐ox speciation and mixing state of iron in individual African dust particles

The Fe distribution in African dust particles collected in Senegal (North‐Western Africa) during the African Monsoon Multidisciplinary Analysis Special Observation Period 0 (AMMA‐“SOP 0,” February 2006) was assessed using individual particle analysis (Scanning and Transmission Electron Microscopy respectively equipped with X‐ray Spectrometry (SEM‐EDX) and Electron Energy Loss Spectrometry (TEM‐EELS)). Senegal is not a dust source area; the chemical composition of collected dusts indicates that they originate primarily in the North‐Western Sahara, which is consistent with previous studies of the area. Fe can be present inside dust particles as a substitution element in the crystalline lattice of aluminosilicate, but a high proportion (62%) of aluminosilicate Fe‐containing particles are also found as an internal mixture of aluminosilicate with Fe oxide grains (including both oxide and hydroxide species). The 3D structure of such particles obtained by tomography reveals that these Fe‐rich inclusions are often found at the surface of aluminosilicate particles but that some are also included inside particles. These Fe oxide grains can result from crustal earth or atmospheric processes during long‐range transport. FeIII is dominant in both the aluminosilicate matrix and the Fe oxide grains (FeIII/Σ Fe ratio = 76.8% and 90.0%, respectively, on average), with notable heterogeneities of Fe valence inside grains at a nanometer scale.

Single-particle Characterization of Aerosol Particles Collected Nearby a Lead Smelter in China

China has been a top producer and exporter of refined lead products in the world since the year 2000. After the phasing-out of leaded gasoline in the late 1990s, non-ferrous metallurgy and coal combustion have been identified as potential major sources of aerosol lead in China. This paper presents the single particle analytical results of ambient aerosol particles collected near a lead smelter using a scanning electron microscopy- energy dispersive x-ray spectroscopy (SEM-EDX). Aerosol particle samples were collected over a 24-hour period, starting from 8 pm on 31 May 2002, using a high volume TSP sampler. For this near source sample, 73 particles among 377 particles analyzed (accounting for 19.4%) were lead-containing particles mixed with other species (S, Cl, K, Ca, and/or C), which probably appeared to be from a nearby lead smelter. Lead-containing particles of less than <TEX>$2{\mu}m$</TEX> size in the near source sample were most frequently encountered with the relative abundances of 42%. SEM-EDX analysis of individual standard particles, such as PbO, PbS, <TEX>$PbSO_4$</TEX>, <TEX>$PbCl_2$</TEX>, and <TEX>$PbCO_3$</TEX>, was also performed to assist in the clear identification of lead-containing aerosol particles. Lead-containing particles were frequently associated with arsenic and zinc, indicating that the smelter had emitted those species during the non-ferrous metallurgical process. The frequently encountered particles following the lead-containing particles were mineral dust particles, such as aluminosilicates (denoted as AlSi), <TEX>$SiO_2$</TEX>, and <TEX>$CaCO_3$</TEX>. Nitrate- and sulfate-containing particles were encountered frequently in <TEX>$2-4{\mu}m$</TEX> size range, and existed mostly in the forms of <TEX>$Ca(NO_3,SO_4)/C$</TEX>, <TEX>$(Mg,Ca)SO_4/C$</TEX>, and <TEX>$AlSi+(NO_3,SO_4)$</TEX>. Particles containing metals (e.g., Fe, Cu, and As) in this near source sample had relative abundances of approximately 10%. Although the airborne particles collected near the lead smelter contained elevated levels of lead, other types of particles, such as <TEX>$CaCO_3$</TEX>-containing, carbonaceous, metal-containing, nitrates, sulfates, and fly-ash particles, showed the unique signatures of samples influenced by emissions from the lead smelter.

Factors Diminishing the Effectiveness of Phosphorus Loading from Municipal Effluent: Critical Information for TMDL Analyses

Factors that diminish the effectiveness of phosphorus inputs from a municipal wastewater treatment facility (Metro) in contributing to phosphorus levels and its availability to support algae growth in a culturally eutrophic urban lake (Onondaga Lake, NY) were characterized and quantified. These factors included the bioavailability and settling characteristics of particulate phosphorus from this effluent, the dominant form (70%) of phosphorus in this input, and the plunging of the discharge to stratified layers in the lake. Supporting studies included: (1) chemical and morphometric characterization of the phosphorus-enriched particles of this effluent, compared to particle populations of the tributaries and lake, with an individual particle analysis technique; (2) conduct of algal bioavailability assays of the particulate phosphorus of the effluent; (3) conduct of multiple size class settling velocity measurements on effluent particles; and (4) determinations of the propensity of the discharge to plunge, and documentation of plunging through three-dimensional monitoring of a tracer adjoining the outfall. All of these diminishing effects were found to be operative for the Metro effluent in Onondaga Lake and will be integrated into a forthcoming phosphorus "total maximum daily load" analysis for the lake, through appropriate representation in a supporting mechanistic water quality model. The particulate phosphorus in the effluent was associated entirely with Fe-rich particles formed in the phosphorus treatment process. These particles did not contribute to concentrations in pelagic portions of the lake, due to local deposition associated with their large size. Moreover, this particulate phosphorus was found to be nearly entirely unavailable to support algae growth. While substantial differences are to be expected for various inputs, the effective loading concept and the approaches adopted here to assess the diminishing factors are broadly applicable.

Peculiarities in the formation of gold nanoparticles by ion implantation in stabilized zirconia

The investigation of bulk single crystals and sputter-deposited films of yttria-stabilized zirconia (YSZ) upon irradiation by gold (Au) ions with an average energy of 160 keV followed by postimplantation annealing revealed peculiarities in the formation of nanocrystalline metal (nc-M) particles in this matrix. In the case of irradiation to small doses (∼5 × 1015 cm−2), the optical absorption spectra of samples showed evidence of the formation of nanoclusters of matrix cations (nc-Zr). In these samples, postimplantation annealing at temperatures ∼700°C and above leads to the formation of nc-Au particles. Local elemental analysis of individual nc-M particles in the YSZ matrix irradiated to a dose of 4 × 1016 cm−2 and annealed at 800°C showed the presence of metal nanoparticles with complex compositions including both implanted Au and matrix Zr atoms.

Sources and Sinks of Phosphorus for a Perturbed Stream and the Effects of Mineral Deposits1

Effler, Steven W., Anthony R. Prestigiacomo, David A. Matthews, and Feng Peng, 2012. Sources and Sinks of Phosphorus for a Perturbed Stream and the Effects of Mineral Deposits. Journal of the American Water Resources Association (JAWRA) 48(2): 321‐335. DOI: 10.1111/j.1752‐1688.2011.00617.xAbstract: Patterns of concentrations and loading rates of multiple forms of phosphorus (P) are resolved and analyzed along Ninemile Creek, New York, a stream perturbed by a domestic waste discharge and residual effects of a closed industry. This analysis is based on biweekly monitoring of total, dissolved, and soluble reactive P (SRP) for 19 months at four sites that bracket each of these effects, and 15 years of biweekly measurements at the two sites that bound industrial deposits. The minerogenic particle populations of the stream and the surficial sediments along the reach with extensive CaCO3 and clay mineral deposits are characterized with an individual particle analysis technique. Mass balance analyses depict: (1) increasing nonpoint inputs of particulate and dissolved organic P along the stream length; (2) input of P from a domestic waste facility, almost entirely in the form of SRP; and (3) a compensating downstream loss of SRP over the reach with the extensive industrial deposits of CaCO3. The downstream sink process for SRP is attributed to sorption processes with minerogenic deposits. The domestic waste‐based source and the compensating industrial waste‐based sink are noteworthy fluxes relative to other prevailing loads received by downstream Onondaga Lake, for which a major rehabilitation program targeting cultural eutrophication is underway. The P source/sink conditions of this stream are considered in the context of this rehabilitation program.

Isotope Ratio Analysis of Individual Plutonium and Uranium–Plutonium Mixed Oxide Particles by Thermal Ionization Mass Spectrometry with a Continuous Heating Method

Abstract Isotope ratio analysis of individual plutonium and uranium–plutonium mixed oxide (MOX) particles was performed using a combination of single particle transfer and thermal ionization mass spectrometry (TIMS) with a continuous heating method, namely the particles were measured without any chemical treatment. Accurate values were obtained for all isotope ratios of the individual particles prepared from standard solution. As a consequence, it is confirmed that the combination method is useful for isotope ratio analysis of individual plutonium and MOX particles.

Org.lcsim: Event Reconstruction in Java

Maximizing the physics performance of detectors being designed for the International Linear Collider, while remaining sensitive to cost constraints, requires a powerful, efficient, and flexible simulation, reconstruction and analysis environment to study the capabilities of a large number of different detector designs. The preparation of Letters Of Intent for the International Linear Collider involved the detailed study of dozens of detector options, layouts and readout technologies; the final physics benchmarking studies required the reconstruction and analysis of hundreds of millions of events.We describe the Java-based software toolkit (org.lcsim) which was used for full event reconstruction and analysis. The components are fully modular and are available for tasks from digitization of tracking detector signals through to cluster finding, pattern recognition, track-fitting, calorimeter clustering, individual particle reconstruction, jet-finding, and analysis. The detector is defined by the same xml input files used for the detector response simulation, ensuring the simulation and reconstruction geometries are always commensurate by construction. We discuss the architecture as well as the performance.

Feasibility Study of Isotope Ratio Analysis of Individual Uranium-Plutonium Mixed Oxide Particles with SIMS and ICP-MS

Isotope ratio analysis of nuclear materials in individual particles is of great importance for nuclear safeguards. Although secondary ion mass spectrometry (SIMS) and thermal ionization mass spectrometry (TIMS) are utilized for the analysis of individual uranium particles, few studies were conducted for the analysis of individual uranium-plutonium mixed oxide particles. In this study, we applied SIMS and inductively coupled plasma mass spectrometry (ICP-MS) to the isotope ratio analysis of individual U-Pu mixed oxide particles. In the analysis of individual U-Pu particles prepared from mixed solution of uranium and plutonium standard reference materials, accurate 235 U/ 238 U, 240 Pu/ 239 Pu and 242 Pu/ 239 Pu isotope ratios were obtained with both methods. However, accurate analysis of 241 Pu/ 239 Pu isotope ratio was impossible, due to the interference of the 241 Am peak to the 241 Pu peak. In addition, it was indicated that the interference of the 238 UH peak to the 239 Pu peak has a possibility to prevent accurate analysis of plutonium isotope ratios. These problems would be avoided by a combination of ICP-MS and chemical separation of uranium, plutonium and americium in individual U-Pu particles.

Characterization of a volcanic ash episode in southern Finland caused by the Grimsvötn eruption in Iceland in May 2011

Abstract. The volcanic eruption of Grimsvötn in Iceland in May 2011 affected surface-layer air quality at several locations in Northern Europe. In Helsinki, Finland, the main pollution episode lasted for more than 8 h around the noon of 25 May. We characterized this episode by relying on detailed physical, chemical and optical aerosol measurements. The analysis was aided by air mass trajectory calculations, satellite measurements, and dispersion model simulations. During the episode, volcanic ash particles were present at sizes from less than 0.5 μm up to sizes &gt;10 μm. The mass mean diameter of ash particles was a few μm in the Helsinki area, and the ash enhanced PM10 mass concentrations up to several tens of μg m−3. Individual particle analysis showed that some ash particles appeared almost non-reacted during the atmospheric transportation, while most of them were mixed with sea salt or other type of particulate matter. Also sulfate of volcanic origin appeared to have been transported to our measurement site, but its contribution to the aerosol mass was minor due the separation of ash-particle and sulfur dioxide plumes shortly after the eruption. The volcanic material had very little effect on PM1 mass concentrations or sub-micron particle number size distributions in the Helsinki area. The aerosol scattering coefficient was increased and visibility was slightly decreased during the episode, but in general changes in aerosol optical properties due to volcanic aerosols seem to be difficult to be distinguished from those induced by other pollutants present in a continental boundary layer. The case investigated here demonstrates clearly the power of combining surface aerosol measurements, dispersion model simulations and satellite measurements in analyzing surface air pollution episodes caused by volcanic eruptions. None of these three approaches alone would be sufficient to forecast, or even to unambiguously identify, such episodes.

Individual particle analysis of aerosols collected under haze and non-haze conditions at a high-elevation mountain site in the North China plain

Abstract. The North China plain is a region with megacities and huge populations. Aerosols over the highly polluted area have a significant impact on the regional and global climate. In order to investigate the physical and chemical characteristics of aerosol particles in elevated layers there, observations were carried out at the summit of Mt. Tai (1534 m a.s.l.) from 19 to 28 April, 2010, when the air masses were advected from the east (phase-I: 19–21 April), from the south (phase-II: 22–25 April), and from the northwest (phase-III: 26–28 April). Individual aerosol particles were identified with transmission electron microscopy (TEM), new particle formation (NPF) and growth events were monitored by a wide-range particle spectrometer, and ion concentrations in PM2.5 were analyzed. During phase-I and phase-II, haze layers caused by anthropogenic pollution were observed, and a high percentage of particles were sulfur-rich (47–49%). In phase-III, the haze disappeared due to the intrusion of cold air from the northwest, and mineral dust particles from deserts were dominant (43%). NPF followed by particle growth during daytime was more pronounced on hazy than on clear days. Particle growth during daytime resulted in an increase of particle geometric mean diameter from 10–22 nm in the morning to 56–96 nm in the evening. TEM analysis suggests that sulfuric acid and secondary organic compounds should be important factors for particle nucleation and growth. However, the presence of fine anthropogenic particles (e.g., soot, metal, and fly ash) embedded within S-rich particles indicates that they could weaken NPF and enhance particle growth through condensation and coagulation. Abundant mineral particles in phase-III likely suppressed the NPF processes because they supplied sufficient area on which acidic gases or acids condensed.