Particle Chemical Composition Research Articles

Ambient Aerosol Is Physically Larger on Cloudy Days in Bondville, Illinois.

Particle chemical composition affects aerosol optical and physical properties in ways important for the fate, transport, and impact of atmospheric particulate matter. For example, hygroscopic constituents take up water to increase the physical size of a particle, which can alter the extinction properties and atmospheric lifetime. At the collocated AERosol RObotic NETwork (AERONET) and Interagency Monitoring of PROtected Visual Environments (IMPROVE) network monitoring stations in rural Bondville, Illinois, we employ a novel cloudiness determination method to compare measured aerosol physicochemical properties on predominantly cloudy and clear sky days from 2010 to 2019. On cloudy days, aerosol optical depth (AOD) is significantly higher than on clear sky days in all seasons. Measured Ångström exponents are significantly smaller on cloudy days, indicating physically larger average particle size for the sampled populations in all seasons except winter. Mass concentrations of fine particulate matter that include estimates of aerosol liquid water (ALW) are higher on cloudy days in all seasons but winter. More ALW on cloudy days is consistent with larger particle sizes inferred from Ångström exponent measurements. Aerosol chemical composition that affects hygroscopicity plays a determining impact on cloudy versus clear sky differences in AOD, Ångström exponents, and ALW. This work highlights the need for simultaneous collocated, high-time-resolution measurements of both aerosol chemical and physical properties, in particular at cloudy times when quantitative understanding of tropospheric composition is most uncertain.

Low-cost zeolitic carriers for delivery of hydroxychloroquine immunomodulatory agent with antiviral activity

The coronavirus pandemic prompted scientists to look for active pharmaceutical ingredients that could be effective in treating COVID-19. One of them was hydroxychloroquine, an antimalarial and immunomodulatory agent exhibiting antiviral activity. The anchoring of this drug on porous carriers enables control of its delivery to a specific place in the body, and thus increases bioavailability. In this work, we developed low-cost zeolitic platforms for hydroxychloroquine. The waste solution generated during zeolite production from fly ashes was used in the synthesis of Na-A and Na-X carriers at laboratory and technical scale. The materials were characterized by high purity and single mineral phase composition. The surface charge of zeolites varied from negative at pH 5.8, and 7.2, to positive at pH 1.2. All samples indicated good sorption ability towards hydroxychloroquine. The mechanism of drug adsorption was based on electrostatic interactions and followed the Freundlich model. Zeolitic carriers modified the hydroxychloroquine release profiles at conditions mimicking the pH of body fluids. The mode of drug liberation was affected by particle size distributions, morphological forms, and chemical compositions of zeolites. The most hydroxychloroquine controlled release at pH 5.8 for the Na-X material was noted, which indicates that it can enhance the drug therapeutic efficacy.

Utilization of high and low calcium oxide fly ashes as the alternative fillers for natural rubber composites: A waste to wealth approach

Recently, fillers from renewable resources or agricultural wastes have been considered as the alternative fillers to reduce the environmental problems. Therefore, utilization of the fly ashes (FA) collected from the electric power plants as the reinforcing filler in natural rubber (NR) composites was carried out and compared these high (HCaO) and low (LCaO) calcium oxides with carbon black (CB). The FA concentration was varied up to an optimum loading of 1000 parts per hundred rubber (phr) by using melt mixing technique. Particle size and chemical composition of HCaO and LCaO were reported and the properties of NR composites in terms of cure characteristics, Payne effect, mechanical and dynamical properties together with morphologies were examined. It was found that the addition of HCaO significantly reduced the vulcanization time of the NR composites, while the one with LCaO provided higher degree of reinforcement efficiency to the NR matrix. It clearly supports the relation of storage modulus as a function of strain sweep and their morphologies, which are the major requirements in case of composites. Upon increasing of FA loading, NR has changed its role from rubber matrix to an adhesive binder and therefore the Young’s modulus was found to be strongly changed. FA can be used to replace CB in NR composites with the composition ratios starting from 1:2–1:6 phr. Although, CB exhibited a slightly better reinforcing effect than FA, based on the lowered glass transition temperature (Tg), Tan delta (Tan δ) exhibited the same elasticity and CB can be replaced in case of several CB-based composites, particularly, the artificial wood, car stopper and tire industries to produce rubber belt and bead.

Significant formation of sulfate aerosols contributed by the heterogeneous drivers of dust surface

Abstract. The importance of dust heterogeneous oxidation in the removal of atmospheric SO2 and formation of sulfate aerosols is not adequately understood. In this study, the Fe-, Ti-, and Al-bearing components, Na+, Cl−, K+, and Ca2+ of the dust surface, were discovered to be closely associated with the heterogeneous formation of sulfate. Regression models were then developed to make a reliable prediction of the heterogeneous reactivity based on the particle chemical compositions. Further, the recognized gas-phase, aqueous-phase, and heterogeneous oxidation routes were quantitatively assessed and kinetically compared by combining the laboratory work with a modelling study. In the presence of 55 µg m−3 airborne dust, heterogeneous oxidation accounts for approximately 28.6 % of the secondary sulfate aerosols during nighttime, while the proportion decreases to 13.1 % in the presence of solar irradiation. On the dust surface, heterogeneous drivers (e.g. transition metal constituents, water-soluble ions) are more efficient than surface-adsorbed oxidants (e.g. H2O2, NO2, O3) in the conversion of SO2, particularly during nighttime. Dust heterogeneous oxidation offers an opportunity to explain the missing sulfate source during severe haze pollution events, and its contribution proportion in the complex atmospheric environments could be even higher than the current calculation results. Overall, the dust surface drivers are responsible for the significant formation of sulfate aerosols and have profound impacts on the atmospheric sulfur cycling.

Impact of powder reusability on batch repeatability of Ti6Al4V ELI for PBF-LB industrial production

ABSTRACT In powder bed fusion laser beam (PBF-LB), powder reusability remains key to keeping cost-effectivity as well as sustainability. In this study, highly sensitive Ti6Al4V ELI powder typically used for medical and aerospace applications is studied. Powder properties of new and reused powders after 10 build cycles subjected to variations such as morphology, particle size distribution (PSD), chemical composition and flowability were analysed. The flow rate using Carney flowmeter increased from 6.8 s to 12 s. Oxygen content slightly increased from 0.11% to 0.12%. The dimensional deviations are measured in six builds of eight samples spread through the build plate. The density of the cubes does not show relevant differences in density (from 99.6% to 99.9%), only the last batch exhibits slightly lower density than the previous builds. Studied properties for the powder and builds are maintained throughout the experiment, demonstrating repeatability of industrial production of metal parts.

Influence of powder production process and properties on material properties of Ti6Al4V manufactured by L-PBF

Besides process parameters, powder properties such as grain size, morphology, and chemical composition have the highest impact on the material properties of parts produced by powder-based additive manufacturing. These properties are strongly influenced by the production process of the powder and its feedstock. In the scope of this work, the influence of three different powder producers of Ti6Al4V, on density, chemical composition, and mechanical properties of build samples, is investigated. Furthermore, the effects of the varying atomization process on morphology, particle size distribution, chemical composition, and oxide layers are studied. Particle size distribution and flowability seem to have a minor influence on the production process while density depends highly on the surface topology, sphericity, and nature of the oxide layer, which affect energy intake. Tensile properties are highly influenced by chemical composition, mainly dissolved oxygen, and polluting satellites, while notched bar impact strength is additionally influenced by the oxide layer and suspected TiO2 precipitations caused by it.

Characterization and Modification of Red Mud and Ferrosilicomanganese Fines and Their Application in the Synthesis of Hybrid Hydrogels.

In this work, hybrid hydrogels were synthesized with the inclusion of two types of clay materials that are considered industrial waste: red mud (RM) and ferrosilicomanganese fines (FeSiMn). These solid waste materials were characterized by studying their particle size and chemical composition, which are two key variables for their application in the synthesis of hybrid hydrogels. The morphology imaged by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), showed, in the case of RM, heterogeneous size and shape particles, with 73% of the particles having lengths of less than 5 μm. On the other hand, FeSiMn had particles with a circular morphology of nanometric sizes. Regarding the synthesis of the hybrid hydrogels, it was determined that the incorporation of small percentages (0.1%) of the inorganic phases improved the capacity of the materials to absorb water (swelling indices of 1678% and 1597% for the RM and FeSiMn hydrogels, respectively) compared to the conventional polyacrylamide hydrogel (1119%). An improvement in Vickers microhardness and storage modulus (G′) was also observed: the hybrid with 10% RM presented a G′, 50 times higher than conventional hydrogel. The results show the merit of RM and FeSiMn in improving the properties of hydrogels.

Effect of PVP surfactant on the synthesis of CuO nanoribbons by the chemical reduction method

This work developed a simple and time-dependent method to synthesize CuO nanoribbons. For this, the concentration of the precursor salt (CuCl2), surfactant (PVP), and reaction times were varied, keeping constant the reducing agent (NaBH4). SEM, TEM, XRD, and EDS characterized CuO ribbon-like particles' morphology, chemical composition, and structure. SEM studies confirmed that CuO nanoribbons appear after three weeks of reaction aging by mixing CuCl2 (17 mM), NaBH4 (26 mM), and PVP (1.6 mM). The nanoribbons have a relatively low aspect ratio of 2 to 3 µm long and around 60 nm wide. XRD and TEM confirmed the monoclinic structure of the CuO nanoribbons. SEM micrographs also indicated that as the salt concentration decreases to 10 mM, the size of the products decreases, and nanosheet-like nanostructures with lengths less than 1 μm and thicknesses of 100 nm are formed. PVP was found to have a great influence on the morphology of the nanostructures. For example, low amounts of PVP increase particle oxidation, easily driving the formation of CuO nanoribbons. At the same time, larger amounts stabilize the formation of Cu2O octahedral particles.

Resuspension of trace explosive particle residues by planar impinging jet: Effects of exposure duration and wall shear stress

Aerodynamic particle resuspension is important in many practical applications, such as surface cleaning, understanding particle fate in the environment, and surface sampling. In practical application, the probability of particle resuspension from the surface depends on several parameters, such as particle size, morphology, chemical composition, surface properties, environmental and flow conditions. The wall shear stress (τw) links fluid motion and forces acting on the particle and can be used to characterize particle resuspension. The literature reports that the resuspension rates decay as 1/t at long exposure times; however, the effect of very short exposures to aerodynamic forces on the resuspension of irregular microparticles has not been characterized. This work examines the effect of τw and exposure duration utilizing planar jet pulses. We evaluated resuspension silica spheres and irregular Trimethylenetrinitramine (RDX) microparticles from a smooth glass surface with a 10–100 ms pulse duration and extended exposure (60 s) for the same wall shear stresses. Reducing the jet duration shows that the removal rate is inversely proportional to exposure time; the trend is more visible at lower τw. At higher shear stresses, up to 80% of particles are removed in the first 10 ms of exposure to aerodynamic force.

Effects of different supplementary cementitious materials on the performance and environment of eco-friendly mortar prepared from waste incineration bottom ash

Municipal solid waste incineration bottom ash (MSWIBA) is a by-product produced by municipal waste incineration treatment. In this study, MSWIBA particle size distribution, chemical composition and particle shape were investigated and confirmed its value for reuse in the construction field and its good research potential. MSWIBA was used as fine aggregates, while coal fly ash (FA) and ground granulated blast furnace slag (GGBFS) were used as auxiliary cementitious materials to replace part of cement to manufacture the eco-friendly mortar (EFM). The effect of FA/GGBFS on the mechanical and microscopic properties of EFM with different material ratios was mainly investigated. And the analysis of the environmental friendliness and economy of this EFM was made. The results show that the combination of FA and GGBFS at the same time reduces the early mechanical properties of the mortar. However, the strength developed rapidly after 7 days, with an increase of more than 6 times the rate before 7 days. Compared with GGBFS, FA is more helpful in improving the mechanical properties of the EFM. After 28 days of full hydration, the hydration products within the EFM are numerous and well bonded to each other. Not only do these hydration products increase the mechanical strength of EFM, but they also successfully solidify the hazardous components in MSWIBA and reduce their negative environmental effects. In addition, the use of MSWIBA instead of sand for mortar preparation reduces energy consumption and CO2 emissions, and it reduces the cost by more than 50 %. This indicates that MSWIBA may perform well in the future development of the civil infrastructures. As well as recycling waste resources, it makes a valuable contribution to the development of green and sustainable building materials.

Characterization of ashes produced from different biomass fuels used in combustion systems in a pulp and paper industry towards its recycling

In the boilers of pulp mills the fuel blends used vary because they are essentially composed of residual forest biomass. Consequently, the physical-chemical properties of the produced ash streams can exhibit high temporal variability, making their proper management and recycling difficult. This study aims to characterize the ash from the incineration of biomass samples used as fuel in order to understand its influence on the properties of the generated ash fluxes. This can anticipate suitable blending procedures that minimize the variability of the ash characteristics. For this purpose, typical biomass samples (eucalyptus bark, treetops and knots, pine treetops, silver wattle, Sydney golden wattle, white poplar, and grey willow) were incinerated (at 550 and 825 °C) and the resulting ashes were characterized. The thermal behavior of the biomass was evaluated by TG/DTA and the generated ash content was determined. The particle size distribution (laser diffraction), morphology (SEM), mineralogy (XRD), and chemical composition (XRF) were other evaluated properties. From the results obtained it is concluded that the ashes cannot be used as raw materials for clinker production. However, they can be used in concrete and mortar formulations, as a cement substitute or as filler. The maximum incorporation amount depends on the type of biomass used, ranging from 54 wt% for pine treetops to 100 wt% for eucalyptus bark. This knowledge is fundamental to understand how to optimize the biomass blends used in industrial combustion systems to obtain ashes with suitable properties to be used as secondary raw materials in building materials formulations.

Reviewing the links and feedbacks between climate change and air pollution in Europe

Feedbacks between air pollutants and meteorology play a crucial role in the direction of the response of future climate and air pollution. These feedbacks are important to understand and quantify the potential impact of adaptation and mitigation policies setup for protecting the population against air pollution and heat stress. We review the interactions between climate and air pollution, with special focus on the projections of air pollution under different future climate scenarios and time horizons, based on a literature review of research articles and reports from the last decade. The assessment focuses on 1) the specific impacts of climate change on air pollution and natural particle and precursor emissions in Europe in the near future (2030), by mid-century (2050) and by end of the century (2100), 2) impacts on air pollution due to changes in emissions vs. changes in climate, 3) feedbacks from air pollution on climate, 4) impacts of climate change on wildland fires and air pollutant levels, and 5) the role of adaptation and mitigation policies on climate change and air pollution. Available literature to a large extent suggests that ozone concentrations will likely increase in the second half of the century by up to 9 ppb [−4 + 9.3], while in the first half of the century, changes are much smaller and are up to ±1.5 ppb. These changes are mainly attributed to increased temperatures and emissions of biogenic volatile organic compounds, but also depends on the models and scenarios used in these studies. On the other hand, the predicted changes in particle concentrations and chemical composition are uncertain and much smaller. Similar to ozone, larger changes in the particle concentrations are projected in the second half of the century. The main conclusion from this review is that the estimated changes in pollutant levels in the future vary significantly depending on the applied model systems, as well as the different emission or meteorological scenarios used in the different studies. Nevertheless, studies generally agree on the overall trend of the changes in pollutant levels due to climate change, in particular in the second half of the century.

Comparison of the Chemical Characteristics and Toxicity of PM2.5 Collected Using Different Sizes of Cyclones

Cyclone sampling devices have been helpful in assessing the toxic effects of fine particulate matter (PM2.5). The particle collection efficiency of sampling devices is critical. This study investigated the effect of cyclone size on particle size, chemical composition, and particle toxicity. Three cyclones with different inner diameters (12–68 mm) were tested for penetration using an aerodynamic particle sizer, fluorescent polystyrene latex, and a differential mobility analyzer. The elemental and water-soluble ion compositions of the particles collected by different cyclones were compared. An evaluation of the particles’ toxicity was conducted by comparing the results of dithiothreitol (DTT), limulus amebocyte lysate (LAL), and cell exposure assays. The experimental evaluation showed a 50% cut-size of the cyclones between 0.17–0.28, 0.34–0.36, and 0.70 μm for the small, medium, and large cyclones, respectively. To collect PM2.5 and evaluate separation performance in the real environment, the small and large cyclones were selected according to the particle penetration and flow rate. A comparison of chemical composition and enrichment factor values found that the particles in the small cyclone samples contained smaller and more anthropogenic sources than those in the large cyclone samples. The oxidative potential (OP) measured by the DTT assay of the samples collected using the small and large cyclones differed across sampling periods and associated with the transition metals. The viability of human epithelial A549 cells after exposure to the collected particles using the cyclones was different across sampling periods and associated with OP. The endotoxin concentrations measured in the LAL assay were found only in the large cyclone samples; they affected the estimated level of cytokine based on IL(interleukin)-6 release from human leukemia monocytic (THP-1) cells derived macro-phage-like cells. Regardless of the size, the cyclone techniques used in this study to collect aerosol particles would be a powerful tool for a detailed evaluation of particle toxicity.

Probing Individual Particles Generated at the Freshwater-Seawater Interface through Combined Raman, Photothermal Infrared, and X-ray Spectroscopic Characterization.

Sea spray aerosol (SSA) is one of the largest global sources of atmospheric aerosol, but little is known about SSA generated in coastal regions with salinity gradients near estuaries and river outflows. SSA particles are chemically complex with substantial particle-to-particle variability due to changes in water temperature, salinity, and biological activity. In previous studies, the ability to resolve the aerosol composition to the level of individual particles has proven necessary for the accurate parameterization of the direct and indirect aerosol effects; therefore, measurements of individual SSA particles are needed for the characterization of this large source of atmospheric aerosol. An integrated analytical measurement approach is required to probe the chemical composition of individual SSA particles. By combining complementary vibrational microspectroscopic (Raman and optical photothermal infrared, O-PTIR) measurements with elemental information from computer-controlled scanning electron microscopy with energy-dispersive X-ray analysis (CCSEM-EDX), we gained unique insights into the individual particle chemical composition and morphology. Herein, we analyzed particles from four experiments on laboratory-based SSA production using coastal seawater collected in January 2018 from the Gulf of Maine. Individual salt particles were enriched in organics compared to that in natural seawater, both with and without added microalgal filtrate, with greater enrichment observed for smaller particle sizes, as evidenced by higher carbon/sodium ratios. Functional group analysis was carried out using the Raman and infrared spectra collected from individual SSA particles. Additionally, the Raman spectra were compared with a library of Raman spectra consisting of marine-derived organic compounds. Saccharides, followed by fatty acids, were the dominant components of the organic coatings surrounding the salt cores of these particles. This combined Raman, infrared, and X-ray spectroscopic approach will enable further understanding of the factors determining the individual particle composition, which is important for understanding the impacts of SSA produced within estuaries and river outflows, as well as areas of snow and ice melt.

Chemical composition of secondary organic aerosol particles formed from mixtures of anthropogenic and biogenic precursors

Abstract. A series of experiments was designed and conducted in the Manchester Aerosol Chamber (MAC) to study the photo-oxidation of single and mixed biogenic (isoprene and α-pinene) and anthropogenic (o-cresol) precursors in the presence of NOx and ammonium sulfate seed particles. Several online techniques (HR-ToF-AMS, semi-continuous GC-MS, NOx and O3 analyser) were coupled to the MAC to monitor the gas and particle mass concentrations. Secondary organic aerosol (SOA) particles were collected onto a quartz-fibre filter at the end of each experiment and analysed using liquid chromatography–ultrahigh-resolution mass spectrometry (LC-Orbitrap MS). The SOA particle chemical composition in single and mixed precursor systems was investigated using non-targeted accurate mass analysis of measurements in both negative and positive ionization modes, significantly reducing data complexity and analysis time, thereby providing a more complete assessment of the chemical composition. This non-targeted analysis is not widely used in environmental science and has never been previously used in atmospheric simulation chamber studies. Products from α-pinene were found to dominate the binary mixed α-pinene–isoprene system in terms of signal contributed and the number of particle components detected. Isoprene photo-oxidation was found to generate negligible SOA particle mass under the investigated experimental conditions, and isoprene-derived products made a negligible contribution to particle composition in the α-pinene–isoprene system. No compounds uniquely found in this system sufficiently contributed to be reliably considered a tracer compound for the mixture. Methyl-nitrocatechol isomers (C7H7NO4) and methyl-nitrophenol (C7H7NO3) from o-cresol oxidation made dominant contributions to the SOA particle composition in both the o-cresol–isoprene and o-cresol–α-pinene binary systems in negative ionization mode. In contrast, interactions in the oxidation mechanisms led to the formation of compounds uniquely found in the mixed o-cresol-containing binary systems in positive ionization mode. C9H11NO and C8H8O10 made large signal contributions in the o-cresol–isoprene binary system. The SOA molecular composition in the o-cresol–α-pinene system in positive ionization mode is mainly driven by the high-molecular-weight compounds (e.g. C20H31NO4 and C20H30O3) uniquely found in the mixture. The SOA particle chemical composition formed in the ternary system is more complex. The molecular composition and signal abundance are both markedly similar to those in the single α-pinene system in positive ionization mode, with major contributions from o-cresol products in negative ionization mode.

Analysis of TRWP Particle Distribution in Urban and Suburban Landscapes, Connecting Real Road Measurements with Particle Distribution Simulation

This article deals with methods and measurements related to environmental pollution and analysis of particle distribution in urban and suburban landscapes. Therefore, an already-invented sampling method for tyre road wear particles (TRWP) was used to capture online emission factors from the road. The collected particles were analysed according to their size distribution, for use as an input for particle distribution simulations. The simulation model was a main traffic intersection, because of the high vehicle dynamic related to the high density of start–stop manoeuvres. To compare the simulation results (particle mass (PM) and particle number (PN)) with real-world emissions, measuring points were defined and analysed over a measuring time of 8 h during the day. Afterwards, the collected particles were analysed in terms of particle shape, appearance and chemical composition, to identify the distribution and their place of origin. As a result of the investigation, the appearance of the particles showed a good correlation to the vehicle dynamics, even though there were a lot of background influences, e.g., resuspension of dust. Air humidity also showed a great influence on the recorded particle measurements. In areas of high vehicle dynamics, such as heavy braking or accelerating, more tyre and brake particles could be found.

STUDY OF THE AERO-DISPERSION SYSTEM IN THE FERROALLOY WORKSHOP WORKING AREA

A large proportion of the gases from the process units in the casting and furnace bays of ferroalloy plants enter the production facilities, where they form a complex aerodisperse system. The resulting aerosols pose a great danger to the operating personnel due to the presence of toxic and carcinogenic components. To develop emission prevention and elimination methods, the sources of industrial aerosol formation during silicomanganese production, particle size distribution and chemical composition of the dust sludge, the behaviour of the gas-dispersed system in the working area have been analyzed. Scanning electron microscope TESCAN VEGA3 with microanalytical attachment Oxford X-Act was used to study the morphology of dust particles sediment. It was established that the aerodisperse system of the shop atmosphere consists of condensation aerosol with submicron particles of manganese and silicon oxides and dispersion aerosol generated mostly at the transportation and loading of charge materials. The behaviour of particles of silicon and manganese oxides, forming a part of the condensed aerosol in the workshop atmosphere was considered. The motion parameters of particles of various chemical compositions simulating compositions of condensation and dispersion aerosols typical of the working area atmospheric aerosol system were calculated. Time and velocity characteristics of aerosol condensation particles for silicon and manganese oxides of 0.1; 1 and 5 microns in diameter are provided.

Factors that govern sub-3 nm particle measurements in an Airmodus® PSM and a TSI® DEG–SMPS

Measurements of sub-3 nm particles are technically challenging and characterized with significant uncertainties. This study selected two types of widely used commercial instruments: an Airmodus® Particle Size Magnifier (PSM) and a TSI® diethylene glycol-based Scanning Mobility Particle Sizer (DEG–SMPS), and examined factors that govern their abilities on measurements of sub-3 nm particles. Monodisperse standard particles used in the experiments include positively and negatively charged tungsten oxide particles and nickel–chromium (Ni/Cr) oxide particles, positive and negative ions produced in a soft X-ray neutralizer, and positively charged organic particles including tetraheptylammonium bromide (THABr), tetrabutylammonium bromide (TBABr), and polyethylene glycol (PEG) particles. Our results show that both PSM and DEG–SMPS are subject to the influence of particle composition. Negatively charged tungsten oxide particles were detected at higher efficiencies than positively charged ones, whereas opposite results were observed for Ni/Cr particles and background ions produced in the soft X-ray neutralizer. In addition, the concentration accuracy of PSM and DEG–SMPS are explored after calibration using Ni/Cr particles. The inverted total concentrations by DEG–SMPS are usually underestimated because of the overestimation of penetration efficiency through different modules, whereas the inverted total concentrations by PSM can be either overestimated or underestimated, when the properties of analyte particles are significantly different from the calibration particles. A better understanding on the effects of particle chemical composition and charging state, and their diffusion losses in the instruments will help to diminish the uncertainties in the measurements.Copyright © 2022 American Association for Aerosol Research.

Secondary inorganic aerosol dominated the light absorption enhancement of black carbon aerosol in Wuhan, Central China

High uncertainty in simulating the climate effect of black carbon (BC)-containing particles can be raised by an important parameter: light absorption enhancement (Eabs), which was impacted by the morphology of BC, its mixing state with coating materials, and the aging process, etc. By a statistical approach called minimum R square (MRS), this study investigated the influence of aerosol chemical compositions on Eabs with on-line observational datasets during summer (June 2018) and winter (December 2018) at an urban site in Wuhan, Central China. The Eabs at 880 nm (Eabs_880) showed a moderate enhancement with a mean value of 1.36 ± 0.35 in summer, which was significantly (p < 0.001) higher than that in winter (1.17 ± 0.24). A proxy defined as the mass ratio of non-refractory chemical components to BC (RBC) was used to link the thickness of BC-containing particles and aerosol chemical compositions with Eabs. With the increase of RBC from 16.4 to 51.3 in summer and from 18.3 to 53.3 in winter, Eabs_880 values amplified by 15.3% and 38.3%, respectively. The statistical and sensitivity analysis indicated that secondary inorganic aerosols (SIA) contributed most to Eabs_880 during summer (92.6%) and winter (71.2%) in Wuhan. Given the dominant mass percentages of SIA in particle chemical compositions and their important role to Eabs, reducing their precursors would benefit to alleviate the particle pollution and the warming effect of BC synergistically. The comparison of Eabs with previous studies suggested that despite the MRS method in this study had some limitations, this method can be widely used in other regions with similar datasets.

High-performance micro/nanoplastics characterization by MALDI-FTICR mass spectrometry

Micro/nanoplastics (MNPs) are widespread environmental pollutants that cause high health risks. However, high heterogeneity in particle sizes and chemical compositions of MNPs make their accurate characterization extremely challenging. Herein, we established a matrix-assisted laser desorption ionization-Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR MS) strategy for the unambiguous characterization of different types of MNPs with high performance, including polystyrene, polyethylene glycol terephthalate, polyamide, polymethyl methacrylate, acrylonitrile butadiene styrene copolymer, and polycarbonate. The MNP sample preparation and detection conditions were systematically optimized by using response surface methodology, and the MS detection signal-to-noise ratios were improved 1.5 times on average. The ultrahigh mass resolution of FTICR MS is crucial to the unambiguous elucidation of MNP structures. We demonstrate that this MS strategy is highly efficient in the characterization of polymer constitutions of environmental MNPs derived from foam, bottles, cable ties, and compact discs, providing a promising tool for MNP detection and safety evaluation.