Electric field and force characteristic of dust aerosol particles on the surface of high-voltage transmission line

High-voltage transmission lines play a crucial role in facilitating the utilization of renewable energy in regions prone to desertification. The accumulation of atmospheric particles on the surface of these lines can significantly impact corona discharge and wind-induced conductor displacement. Accurately quantifying the force exerted by particles adhering to conductor surfaces is essential for evaluating fouling conditions and making informed decisions. Therefore, this study investigates the changes in electric field intensity along branched conductors caused by various fouling layers and their resulting influence on the adhesion of dust particles. The findings indicate that as individual particle size increases, the field strength at the top of the particle gradually decreases and eventually stabilizes at approximately 49.22 k V/cm, which corresponds to a field strength approximately 1.96 times higher than that of an unpolluted transmission line. Furthermore,when particle spacing exceeds 15 times the particle size, the field strength around the transmission line gradually decreases and approaches the level observed on non-adhering surface. The electric field remains relatively stable. In a triangular arrangement of three particles, the maximum field strength at the tip of the fouling layer is approximately 1.44 times higher than that of double particles and 1.5 times higher compared to single particles. These results suggest that particles adhering to the transmission line have a greater affinity for adsorbing charged particles. Additionally, relevant numerical calculations demonstrate that in dry environments, the primary adhesion forces between particles and transmission lines follow an order of electrostatic force and van der Waals force. Specifically, at the minimum field strength, these forces are approximately74.73 times and 19.43 times stronger than the gravitational force acting on the particles.

Size,composition,and mixing state of individual aerosol particles in a South China coastal city

Aerosol samples were collected in summer in Macao, a coastal city of the Pearl River Delta Region in China. Morphology, size, elemental composition, and mixing state of individual aerosol particles were determined by scanning electron microscopy coupled energy dispersive X-ray （SEM/EDX） and transmission electron microscopy （TEM）. Based on the morphologies of 5711 aerosol particles, they consist of soot （32%）, mineral （17%）, secondary-（22%）, and unknown fine particles （29%）. The sizes of these particles were mostly distributed between 0.1 and 0.4 μm. Compositions of 202 mineral particles were obtained by SEM/EDX. Mineral particles were mainly classified into three types： Si-rich, Ca-rich, and Na-rich. The compositions of typical mineral particles can indicate their sources in sampling location. For example, mineral particles, collected along the main street, were associated with trace amounts of heavy metals, such as Zn, Ti, Mn, Ba, Pb, and As. TEM observations indicate that most Na-rich particles were aged sea salt particles （e.g., Na2SO4 and NaNO3） which formed through heterogeneous chemical reactions between sea salt and acidic gases. Additionally, aging time of soot was short in Macao due to high humidity, high temperature, and high levels of sunlight in Macao. Most of soot and fine mineral dust particles were internally mixed with secondary particles.

Seasonal features of aerosol particles recorded in snow from Mt. Qomolangma (Everest) and their environmental implications

To assess the seasonality of aerosol deposition and anthropogenic effects on central Himalayas, a 1.85-m deep snow pit was dug on the northern slope of Mt. Qomolangma （Everest）. Based on the morphology and energy dispersive X-ray （EDX） signal, totally 1500 particles were classed into 7 groups： soot; aluminosilicates; fly ash; calcium sulfates; Ca/Mg carbonates; metal oxides; and biological particles and carbon fragments. The size distribution and number fractions of different particle groups exhibited distinct seasonal variations between non-monsoon and monsoon periods, which are clearly related to the differences in air mass pathways. Specifically, the relative abundance of soot in non-monsoon period （25%） was much higher than that in monsoon period （14%）, indicating Mt. Qomolangma region received more anthropogenic influence in non-monsoon than monsoon period.

The collision efficiency of spherical dioctyl phthalate aerosol particles in the Brownian coagulation

The collision efficiency in the Brownian coagulation is investigated. A new mechanical model of collision between two identical spherical particles is proposed, and a set of corresponding collision equations is established. The equations are solved numerically, thereby obtaining the collision efficiency for the monodisperse dioctyl phthalate spherical aerosols with diameters ranging from 100 to 760 nm in the presence of van der Waals force and the elastic deformation force. The calculated collision efficiency, in agreement with the experimental data qualitatively, decreases with the increase of particle diameter except a small peak appearing in the particles with a diameter of 510 nm. The results show that the interparticle elastic deformation force cannot be neglected in the computation of particle Brownian coagulation. Finally, a set of new expressions relating collision efficiency to particle diameter is established.

Growth Rates of Fine Aerosol Particles at a Site near Beijing in June 2013

Growth of fine aerosol particles is investigated during the Aerosol-CCN-Cloud Closure Experiment campaign in June 2013 at an urban site near Beijing. Analyses show a high frequency （- 50%） of fine aerosol particle growth events, and show that the growth rates range from 2.1 to 6.5 nm h-1 with a mean value of - 5.1 nm h-1. A review of previous studies indicates that at least four mechanisms can affect the growth of fine aerosol particles： vapor condensation, intramodal coagulation, extramodal coagulation, and multi-phase chemical reaction. At the initial stage of fine aerosol particle growth, condensational growth usually plays a major role and coagulation efficiency generally increases with particle sizes. An overview of previous studies shows higher growth rates over megacity, urban and boreal forest regions than over rural and oceanic regions. This is most likely due to the higher condensational vapor, which can cause strong condensational growth of fine aerosol particles. Associated with these multiple factors of influence, there are large uncertainties for the aerosol particle growth rates, even at the same location.

Study on optical constants inversion and infrared transmission characteristics of aerosol particles

Based on the experimental infrared spectral transmittances,an inverse model has been developed to determine the optical constants of the aerosol particles (SiO2 and Al2O3).Combined with the Mie theory and Kramers-Kronig (K-K) relations,the complex refractive indices of the SiO2 and Al2O3 particles are retrieved.The effects of the measurement errors on the inverse results are also investigated.With the optical constants inversed from the experiment,the discrete ordinate method (DOM) is used to calculate the infrared transmission characteristics of the aerosol particle cloud.Considering the multi-scattering and self-emission of the particles,the equivalent transmittance ratio (ETR) is suggested to evaluate the infrared transmission characteristics of the aerosol particles.Particular attention is given to analyze the effects of the volume fraction and diameters on infrared transmission characteristics.When the volume fraction is larger than 0.001,the particle diameter has little effect on the infrared transmission characteristics.For the uniform monodisperse particles in the detection waveband range of 3-5 μm and 8-12 μm,there exists a critical diameter where the ETR reaches the minimum value.In addition,the ETR of 3-5 μm is smaller than that of 8-12 μm with the same volume fraction and particle diameter.

Effect of Aerosol Particles on Orographic Clouds:Sensitivity to Autoconversion Schemes

Aerosol particles can serve as cloud condensation nuclei(CCN)to influence orographic clouds.Autoconversion,which describes the initial formation of raindrops from the collision of cloud droplets,is an important process for aerosol-cloud-precipitation systems.In this study,seven autoconversion schemes are used to investigate the impact of CCN on orographic warm-phase clouds.As the initial cloud droplet concentration is increased from 100 cm^(-3)to 1000 cm^(-3)(to represent an increase in CCN),the cloud water increases and then the rainwater is suppressed due to a decrease in the autoconversion rate,leading to a spatial shift in surface precipitation.Intercomparison of the results from the autoconversion schemes show that the sensitivity of cloud water,rainwater,and surface precipitation to a change in the concentration of CCN is different from scheme to scheme.In particular,the decrease in orographic precipitation due to increasing CCN is found to range from-87%to-10%depending on the autoconversion scheme.Moreover,the surface precipitation distribution also changes significantly by scheme or CCN concentration,and the increase in the spillover(ratio of precipitation on the leeward side to total precipitation)induced by increased CCN ranges from 10%to 55%under different autoconversion schemes.The simulations suggest that autoconversion parameterization schemes should not be ignored in the interaction of aerosol and orographic cloud.

Evolution of Small Scale Density Perturbations of Plasma and Charged Aerosol Particles in Polar Mesospheric Summer Echoes (PMSE) Layers

Time evolution of ionospheric D-region plasmas including the perturbations of electrons and charged aerosol particles is investigated under the conditions of polar mesosphere summer echoes （PMSE）. It is shown that the time scale of decay of the electron density is in the order of an hour under typical PMSE conditions, in the majority of cases, the electron density is anticorrelated to the ion density, except that the radius of aerosol particles is greater than 50 nm. Also, the evolutions under varied parameters, such as the amplitude and width of perturbation, the aerosol particle radius, and the altitude of the PMSE occurrence are investigated. The obtained results are useful for interpreting the experimental observations.

Density Function Theory Study on the Reaction Mechanism of Cerium with Oxygen for Ce-bearing Aerosol Particle Formation

We obtained the reaction mechanism of cerium with oxygen by means of density functional theory (DFT) under the explosive or detonation situation. The energy level order of cerium was calculated and the potential energy profile was plotted. The properties of the bonds of all special structures in the reaction path were analyzed using the method of the electron localization function (ELF). The results indicate that the final reaction pathway can be expressed as Ce+O2→ FC→TS→IM→O-Ce-O, and the formation of Ce2O3 has not been found. In addition, the ELF diagram of the final product CeO2 shows that Ce bonds with both O atoms and the bond angles increase significantly.

Insight into the interaction between water and surfactant aerosol particles based on molecular dynamics simulations

The ubiquitous surfactant significantly influences the hygroscopic growth of atmospheric aerosol par-ticles.However,knowledge on the morphology of surfactant particles after the adsorption of water is insufficient.In this study,the interaction between water and particles composed of surface active malonic acid(MA)or adipic acid(AA)are simulated based on the molecular dynamics method.The key point is the combined effect of temperature and water content on the structural properties of particles and the surface propensity of surfactants at the equilibrium state.Results show that demixed structure 1 with the adsorption of water clusters on acid grain,mixed structure and demixed structure 2 with acids coating on water droplet can be observed.With temperature increasing from 160 K to 330 K the surface propensity of MA and AA increases first and then weakens.Near the standard atmospheric temperature(280-330 K),the surface propensity of MA and AA increases with increasing water content and alkyl group,and its sensitivity to temperature and water content varies regularly.Moreover,all surfactants at the particle surface orient their hydrophobic groups toward the gas.These findings improve our insight into the surfactant partitioning and further assist in more accurate prediction of the particle hygroscopic growth.

Characterization of seawater and aerosol particle surfactants using solid phase extraction and mass spectrometry

Surface-active organic molecules(surfactants)may influence the ability of an aerosol particle to act as a cloud condensation nuclei by reducing its surface tension.One source of organic mass in aerosol particles,which may also contain surfactants,is bubble bursting on the sea surface.In order to directly compare these molecules in the ocean and aerosol particles,we developed a method using multiple solid phase extractions and high resolution mass spectrometry to characterize surface active organic molecules in both.This method has extraction efficiencies greater than 85%,75%,and 60%for anionic,cationic,and nonionic surfactant standards,respectively.In this study,we demonstrate the presence of three ionic classes of surface active organics in atmospheric aerosol particles and estuarine water from Skidaway Island,GA.With this extraction method,organic molecules from both estuarine water and atmospheric aerosol particles significantly reduced surface tension of pure water(surface tension depression of~18 m N/m)and had high ratios of hydrogen to carbon(H/C)and low ratios of oxygen to carbon(O/C),indicative of surfactants.While previous work has observed a larger fraction of anionic surface active organics in seawater and marine aerosol particles,here we show cationic surface active organics may make up a large fraction of the total surface active molecules in estuarine water(43%–47%).

Origin,evolution,and distribution of atmospheric aerosol particles in Asia

In recent years, Asia became the region with the highest increase in rate of urbanization and economic development in the world. According to recent estimates from the United Nations, the world population will increase 36% between 2000 and 2030, leading to a doubling of the number of urban dwellers in less developed regions, like Asia. Such rapid economic development has many associated environmental problems, including development of heavy aerosol pollution over Asia.

Charging states on atmospheric aerosol particles affected by meteorological conditions

Previous studies on haze formation focused mainly on the various chemical components in aerosol particles and their physicochemical effects on particle behaviour(e.g.,generation,growth,and agglomeration).This paper describes the measurement of the charging state on atmospheric aerosol particles,which could be affected by meteorological conditions.A series of experiments on particle charging state and meteorological factors was undertaken on the roof of the west 4th building on the Qujiang Campus at Xi'an Jiaotong University(China).Measurements were conducted approximately 20 m above ground level,Our results showed that most atmospheric particles carried net negative or positive charge and that the electric charge on the particles varied diurnally and seasonally.The average amount of charge on particles was higher in winter than in summer.The number concentration of charged particles was higher during the day than overnight.Obvious difference in the average charge of aerosol particles was found between sand-dust days and haze days.A strong relationship was found between the PM2.s concentration,charge amount on particles,and humidity.Our findings show that particle formation and growth could partly be attributed to variation in particle charging state,which is related to meteorological conditions including atmospheric humidity.

PRELIMINARY STUDY OF VARIATION OF SO_2 AND AEROSOL PARTICLE BACKGROUND CONCENTRATIONS IN THE EASTERN CHINA

The average concentrations of sulphur dioxide,sulfate aerosol and TSP were about 8—10 ppb,15.08 μg m^(-3),and 241.40 μg m^(-3) respectively,which were measured at the Lin'an regional background station during August— November,1991.The higher concentrations of SO_2 and SO_4^(2-) maybe acidify the rainfall.It has a great influence upon the human health and ecosystem.The simulated results indicate that the distributions of SO_2 and SO_4^(2-) were deter- mined by local emission sources.Average aerosol particle number density was 2.0×10~4 cm^(-3).It shows that social devel- opment and human activities strongly affect the atmospheric background level.

A Comparison of Two Bulk Microphysics Parameterizations for the Study of Aerosol Impacts on an Idealized Supercell

Idealized supercell storms are simulated with two aerosol-aware bulk microphysics schemes(BMSs),the Thompson and the Chen-Liu-Reisner(CLR),using the Weather Research and Forecast(WRF)model.The objective of this study is to investigate the parameterizations of aerosol effects on cloud and precipitation characteristics and assess the necessity of introducing aerosols into a weather prediction model at fine grid resolution.The results show that aerosols play a decisive role in the composition of clouds in terms of the mixing ratios and number concentrations of liquid and ice hydrometeors in an intense supercell storm.The storm consists of a large amount of cloud water and snow in the polluted environment,but a large amount of rainwater and graupel instead in the clean environment.The total precipitation and rain intensity are suppressed in the CLR scheme more than in the Thompson scheme in the first three hours of storm simulations.The critical processes explaining the differences are the auto-conversion rate in the warm-rain process at the beginning of storm intensification and the low-level cooling induced by large ice hydrometeors.The cloud condensation nuclei(CCN)activation and auto-conversion processes of the two schemes exhibit considerable differences,indicating the inherent uncertainty of the parameterized aerosol effects among different BMSs.Beyond the aerosol effects,the fall speed characteristics of graupel in the two schemes play an important role in the storm dynamics and precipitation via low-level cooling.The rapid intensification of storms simulated with the Thompson scheme is attributed to the production of hail-like graupel.

Observed Changes in Aerosol Physical and Optical Properties before and after Precipitation Events

Precipitation scavenging of aerosol particles is an important removal process in the atmosphere that can change aerosol physical and optical properties. This paper analyzes the changes in aerosol physical and optical properties before and after four rain events using in situ observations of mass concentration, number concentration, particle size distribution, scattering and absorption coefficients of aerosols in June and July 2013 at the Xianghe comprehensive atmospheric observation station in China. The results show the effect of rain scavenging is related to the rain intensity and duration, the wind speed and direction. During the rain events, the temporal variation of aerosol number concentration was consistent with the variation in mass concentration, but their size-resolved scavenging ratios were different. After the rain events, the increase in aerosol mass concentration began with an increase in particles with diameter ＆lt;0.8 μm [measured using an aerodynamic particle sizer（APS）], and fine particles with diameter ＆lt;0.1 μm [measured using a scanning mobility particle sizer（SMPS）]. Rainfall was most efficient at removing particles with diameter ～0.6 μm and greater than 3.5 μm. The changes in peak values of the particle number distribution（measured using the SMPS） before and after the rain events reflect the strong scavenging effect on particles within the 100–120 nm size range. The variation patterns of aerosol scattering and absorption coefficients before and after the rain events were similar, but their scavenging ratios differed, which may have been related to the aerosol particle size distribution and chemical composition.

Elemental Composition of PM2.5 and PM10 in the Industrial Area of Yopougon, Abidjan, Côte d’Ivoire

This paper describes the evaluation of trace element composition of atmospheric aerosol particles (PM2.5 and PM10) and their influence on air quality in the largest industrial area of Abidjan city, C?te d’Ivoire. Multi-week sampling was conducted in an urban site (industrial area) in Abidjan from April 2018 to July 2019. The mean mass concentration was 48.83 ± 15.24 μg/m3 for PM2.5 and 77.34 ± 10.91 μg/m3 for PM10, with significant temporal variability. The average ratio of PM2.5/PM10 was 0.64 ± 0.21. The concentration of BC in PM2.5 and PM10 was respectively 52.32 ± 7.48 μg/m3 and 52.26 ± 12.07 μg/m3. Twenty-two elements: Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Zr and Pb were analysed by Energy Dispersive X-ray Fluorescence (EDXRF). Elemental composition data were modeled using principal component analysis (PCA) with varimax rotation to determine two (2) and four (4) dominant source categories contributing to PM2.5 and PM10 respectively. In the case of fine particles PM2.5, the possible sources were Industrial activities and non-exhaust emissions, exhaust emissions. The PM10 sources were industrial activities and non-exhaust emissions, industrial processes, mineral dust, and waste combustion.

A model for aerosol mass concentration using an optical particle counter

A model for measuring aerosol mass concentration by an optical particle counter is presented using the conception of the average mass. In this model, to understand the meaning of the pulse height distribution of particles which is used to inverse mass concentration, the relationship among intensity distribution in the optical sensing volume, particle shape, and the pulse height distribution is discussed. To solve the instability of the equivalent factor, a novel two-step calibration method is proposed. The experimental results demonstrate that mass concentrations calculated by the model are in good agreement with those measured by a norm-referenced instrument. For samples of soot and air, the slopes of fitting lines of data points are 0.9582 and 0.9220, and the correlation coefficients are 0.9991 and 0.9965, respectively.

Effective platform for the generation of aerosol droplets and application in evaluating the effectiveness of a MEMS-based nanoparticle trapping device

The purpose of this study is two-fold： firstly, the development of a cheap, easy-to-construct and effective nanoparticle generator for testing nanoparticle sensors; secondly, the use of such a generator to test the effectiveness of a sensor device in trapping aerosolised nanoparticles. In this study, we have constructed an effective aerosol generator platform, based on aerosol-assisted chemical vapour deposition technology. Under well-controlled experimental conditions, this platform is capable of depositing aerosolised sodium chloride particles homogeneously on a substrate very effectively. Deposited aerosol droplets were subsequently dried and shown to form nanosized cubic crystals that are free from impurities. This platform was employed to test the effectiveness of a MEMS comb device in the electrostatic trapping of nanoparticles. Upon applying a DC bias （0.5 V） to the MEMS device, results showed an increase in nanoparticle deposition on the surface of the device, due to electrostatic precipitation. The presence of an electric field was shown to affect crystal formation upon drying of the aerosol droplets on the substrate; this caused a blotchy appearance on the SEM image, which was not observed in the absence of electric field.

Organic aerosol molecular composition and gas–particle partitioning coefficients at a Mediterranean site(Corsica)

Molecular speciation of atmospheric organic matter was investigated during a short summer field campaign performed in a citrus fruit field in northern Corsica（June 2011）. Aimedat assessing the performance on the field of newly developed analytical protocols, this work focuses on the molecular composition of both gas and particulate phases and provides an insight into partitioning behavior of the semi-volatile oxygenated fraction. Limonene ozonolysis tracers were specifically searched for, according to gas chromatography–mass spectrometry（GC–MS） data previously recorded for smog chamber experiments. A screening of other oxygenated species present in the field atmosphere was also performed. About sixty polar molecules were positively or tentatively identified in gas and/or particle phases. These molecules comprise a wide range of branched and linear, mono and di-carbonyls（C_3–C7）,mono and di-carboxylic acids（C_3–C_18）, and compounds bearing up to three functionalities.Among these compounds, some can be specifically attributed to limonene oxidation and others can be related to α- or β-pinene oxidation. This provides an original snapshot of the organic matter composition at a Mediterranean site in summer. Furthermore, for compounds identified and quantified in both gaseous and particulate phases, an experimental gas/particle partitioning coefficient was determined. Several volatile products, which are not expected in the particulate phase assuming thermodynamic equilibrium, were nonetheless present in significant concentrations. Hypotheses are proposed to explain these observations, such as the possible aerosol viscosity that could hinder the theoretical equilibrium to be rapidly reached.