Search

The eruption of Mount Cumbre Vieja, La Palma, Spain, on 19th September 2021 released large amounts of gas and volcanic ash into the atmosphere that spread over hundreds of kilometers. Subsequently, the volumes of gaseous, and water vapor components in the troposphere were highly disturbed. In general, the release of a large amount of water vapor during an eruption increases the value of path delay and vertical column density of SO2. Therefore, this study analyzed their variations to determine the impact of eruption. The precise point positioning on Global Navigation Satellite System (GNSS) observation data were processed to obtain zenith tropospheric delay (ZTD) and precipitable water vapor (PWV) contents, while Sentinel 5P, and MODIS remote sensing imagery were used to determine SO2 column density, aerosol index, and surface temperature. Moreover, time series and correlation analysis were computed to analyze the effect of the eruption and the relationship between GNSS and remote sensing parameters. Our findings showed that the variations in precipitable water vapor affected the ZTD value for three GNSS stations around the eruption point, showing a correlation value above 0.98. Meanwhile, the remote sensing data indicated that the SO2 content peaked at the end of September and in October 2021. Similarly, tropospheric delay, and water vapor had the highest fluctuations and increases in the early eruption period. However, the lower atmosphere layer was generally influenced by the autumn climate. The content of particles released into the atmosphere during eruption had minor effect in the middle to the end of the eruption period as rainfall events led to an increase in water vapor. The surface temperature was found to be characterized mostly by autumn condition but showed fluctuations and increased values in the early period of the eruption. [ABSTRACT FROM AUTHOR]

Introduction: Implementing control plans, monitoring, and formulating traffic and management laws requires obtaining basic information about the origin of particles, physicochemical properties, and their behavior in the atmosphere. Gathering this information requires studying the various dimensions of the nature of particles, most of which will not be directly possible. The challenge of air pollution in the metropolis of Tehran requires fundamental studies, and in this study, we tried to present new dimensions of physicochemical and fundamental properties of atmospheric particles in Tehran. Material and methods: The particle collection process to evaluate their concentration and chemical composition was performed by a high-volume sampler for 1 to 24 hours and an average flow of 1.7 m3/min on fiberglass filters. Also, to determine the aerodynamic diameter distribution of the particles, a cascade sampler (Anderson impactor) with a flow of 28.3.3 L/min was used for 72 hours to 7 days. After sampling, the samples were prepared to determine the total concentration and aerodynamic distribution in the laboratory. Results and discussion: The results showed that the mean particle concentration during the sampling period was 118.6 ± 11.9 µg/m3. During the sampling period, the highest concentration of collected particles was 154.61 ± 22.1 and the lowest was 129/12 ± 23.15 µg/m3. The results of SEM analysis of the collected samples showed that the particles were present in a spherical, irregular, fibrous shape as well as crystalline shape. The predominant elements in these samples are K, Ca, Cl and Fe, which are found in combination with Ti, Zn. Cluster-like and amorphous structures rich in O, Zn, Mg, Fe, K, Si, and Na were observed in particles with dimensions of 2 to 7 micrometers. Conclusion: According to the results and comparison with other work done in this field, more particulate matter is emitted during fuel combustion processes by industry and urban transportation. Larger particles are also produced and emitted by vehicles, construction, and industry during human activities such as road dust.

This paper presents the light-scattering matrices of atmospheric-aggregated hexagonal ice particles that appear in cirrus clouds. The aggregates consist of the same particles with different spatial orientations and numbers of these particles. Two types of particle shapes were studied: (1) hexagonal columns; (2) hexagonal plates. For both shapes, we studied compact and non-compact cases of particle arrangement in aggregates. As a result, four sets of aggregates were made: (1) compact columns; (2) non-compact columns; (3) compact plates; and (4) non-compact plates. Each set consists of eight aggregates with a different number of particles from two to nine. For practical reasons, the bullet-rosette and the aggregate of hexagonal columns with different sizes were also calculated. The light scattering matrices were calculated for the case of arbitrary spatial orientation within the geometrical optics approximation for sets of compact and non-compact aggregates and within the physical optics approximation for two additional aggregates. It was found that the light-scattering matrix elements for aggregates depend on the arrangement of particles they consist of. [ABSTRACT FROM AUTHOR]

Atmospheric particulate pollution is one of the most common pollution related issues and poses a serious threat to human health. PM2.5 and PM10 are important indicators of atmospheric particulate pollution currently. Based on the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model, the hourly 72 h backward trajectory of particulate matter in Xi'an from March 2019 to February 2022 was calculated, and the main path of air flow to Xi'an was studied by cluster analysis. Combined with hourly concentration monitoring data of PM2.5 and PM10 at each station, the potential source area of particles in Xi'an was calculated by potential source contribution factor analysis and concentration weighted trajectory analysis. The results show that Xi'an was most polluted in winter, followed by autumn and spring, and cleanest in the summer. The annual average mass concentrations of PM2.5 and PM10 are 48.5 ± 28.7 μg/m3 and 89.2 ± 39.2 μg/m3, respectively, both exceeding the national secondary standard for ambient air quality. On an annual basis, back-trajectory analysis showed that predominantly transport was rapid from the northwest (44%). Transport from the other sectors were 24%, 19%, and 14% from the northeast, southeast, and southwest, respectively, and featured lower windspeeds on average. The potential source areas of particulate matter in Xi'an in the spring are mainly located at the junction of Chongqing, Hunan, and Hubei, and parts of the southeast and north of Sichuan. This study provides context for air quality and atmospheric transport conditions in this region of China. [ABSTRACT FROM AUTHOR]

Introduction: Implementing control plans, monitoring, and formulating traffic and management laws requires obtaining basic information about the origin of particles, physicochemical properties, and their behavior in the atmosphere. Gathering this information requires studying the various dimensions of the nature of particles, most of which will not be directly possible. The challenge of air pollution in the metropolis of Tehran requires fundamental studies, and in this study, we tried to present new dimensions of physicochemical and fundamental properties of atmospheric particles in Tehran. Material and methods: The particle collection process to evaluate their concentration and chemical composition was performed by a high-volume sampler for 1 to 24 hours and an average flow of 1.7 m3/min on fiberglass filters. Also, to determine the aerodynamic diameter distribution of the particles, a cascade sampler (Anderson impactor) with a flow of 28.3.3 L/min was used for 72 hours to 7 days. After sampling, the samples were prepared to determine the total concentration and aerodynamic distribution in the laboratory. Results and discussion: The results showed that the mean particle concentration during the sampling period was 118.6 ± 11.9 μg/m3. During the sampling period, the highest concentration of collected particles was 154.61 ± 22.1 and the lowest was 129/12 ± 23.15 μg/m3. The results of SEM analysis of the collected samples showed that the particles were present in a spherical, irregular, fibrous shape as well as crystalline shape. The predominant elements in these samples are K, Ca, Cl and Fe, which are found in combination with Ti, Zn. Cluster-like and amorphous structures rich in O, Zn, Mg, Fe, K, Si, and Na were observed in particles with dimensions of 2 to 7 micrometers. Conclusion: According to the results and comparison with other work done in this field, more particulate matter is emitted during fuel combustion processes by industry and urban transportation. Larger particles are also produced and emitted by vehicles, construction, and industry during human activities such as road dust. [ABSTRACT FROM AUTHOR]

Abstract To solve the challenge of extracting nano- to micrometer-sized atmospheric particles from a mixed sample, we developed an electrostatic sieve system, the Fine Sieving of Collected Atmospheric Particles using Oil Electrophoresis (iSCAPE), based on the application of an electrostatic field to a non-conductive mineral oil. Using atmospheric samples, which were collected from different cities, in addition to soil and road dust samples, we tested this system under different conditions and found that the “iSCAPE’d” particles moved rapidly at varying velocities and in two opposite directions. The diverse origins of the sample—ambient air, soil, or road dust—exhibited specific charged properties, and clearly affected the electrical mobility, as demonstrated by the graphs, of the particles following the “iSCAPEing,” which lasted from seconds to minutes. We also observed an increased abundance of particles in specific mobility ranges. Furthermore, according to our adenosine triphosphate (ATP) monitoring results, the iSCAPE is capable of separating bacterial particles by size and electrical mobility. The experimental data suggests that the iSCAPE relies heavily on the electrostatic field strength, mineral oil viscosity, and run time. In theory, this method can extract any targets from a complex sample, thus creating many research opportunities in environmental, biomedical, and life sciences.

Residents in arid regions of northwest China, where dust storms are more common, are continually exposed to air pollution particularly fine particles of PM2.5 and PM10, causing health hazards to residents. Urban greening species have a strong dust retention capacity which is also available in arid conditions and should be chosen to reduce the impact of air pollution on people and the urban environment. In this paper, three common tree species in four different functional areas: Transportation area (TA), Residential area (RA), Industrial area (IA), and Clean area (CA) of Aksu City were selected to measure their foliar dust to select the matching trees for appropriate sites. The dust particle size distribution for PM2.5 and PM10 was analyzed to explore the particle size difference between foliar dust and natural landing dust. The largest particle size was recorded in IA (168.56 µm), while the smallest was found in CA (43.25 µm). Furthermore, Salix babylonica (S. babylonica) absorbed the highest PM2.5 and PM10, 0.15% and 1.39% respectively; while Ulmus densa (U. densa) absorbed the least PM2.5 and PM10, 0.08% and 0.37%. Platanus acerifolia (P. acerifolia) foliar dust particle density was the highest, and has stable dust retention capacity, while, S. babylonica foliar dust particulate density is the lowest under the same conditions (height/location, pollution exposition, weather). Our findings concluded that the average values of dust diameters in the four areas differed significantly. It is concluded that P. acerifolia is the best performer in removing dust in different functional urban areas and S. babylonica was more suitable for CA because of having the capacity to remove fine particle matter. [ABSTRACT FROM AUTHOR]

Wheat flag leaf (FL) is one of the primary sources of carbohydrates in grains; however, its role in grain lead (Pb) absorption remains unclear. A field experiment was conducted to assess the relative contribution of the FL to Pb accumulation in wheat grain by two contrasting treatments: without (CK) and with FL removal (FLR) at the grain-filling stage. The Pb concentration in leaves was closely related to leaf strata and decreased from FL to the third leaf. FLR treatment significantly reduced the yield and grain Pb concentration by 2.79% and 11.47%, respectively. The contribution of FL to grain Pb accumulation decreased gradually with the filling process, from 35.08% (at early stage) to 13.94% (at maturity stage). After FLR, the contribution proportion of atmospheric fallout to grain Pb decreased from 69.01% (CK) to 62.43% (FLR). Combined isotope analysis with scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS) revealed that the main contribution of FLs to grain Pb originated from Pb fallout in fine atmospheric particles. Therefore, taking measures to reduce the influence of fine atmospheric particles on wheat may be an effective way to control wheat grain Pb contamination.

An interlaboratory study of the National Institute for Environmental Studies (NIES) certified reference material (CRM) No. 28 Urban Aerosols collected from the filters of a central ventilating system in a building in the Beijing city center from 1996 to 2005 was performed to obtain an information value of the Sr isotopic composition. The Sr isotopic composition was measured using multi-collector-inductively coupled plasma-mass spectrometry (MC-ICP-MS) to confirm the CRM’s within- and between-bottle homogeneity, and the results showed a 87Sr/86Sr ratio of 0.710227 ± 0.000019 (2SD, n = 18). The Sr isotopic compositions were intercompared using thermal ionization mass spectrometry (TIMS), which showed good agreement with values obtained at NIES. Subsequently, a consistent 87Sr/86Sr ratio was observed between two dissolution (hotplate vs. high-pressure bomb) and Sr separation (Sr spec resin vs. cation exchange resin) methods. To validate and reproduce the accuracy of our analytical methods, the Sr isotopic compositions of secondary reference materials, JB-1b and JA-2, were also measured. Our results showed that NIES CRM No. 28 is appropriate for the quality control of Sr isotope measurements of particulate matter analyses for environmental and geochemical studies.

Polycyclic aromatic hydrocarbons (PAHs) have the capability for solar radiation absorption related to climate forcing. Herein, pollution characteristics and absorption spectra of size-resolved PAHs in atmospheric particles in a cold megacity were comprehensively investigated. The mean concentrations of Σ 18 PAHs in all the 11 particle size ranges were 3.95 ± 4.77 × 104 pg/m3 and 2.17 ± 1.54 × 103 pg/m3 in heating period (HP) and non-heating period (NHP), respectively. Except for most PAHs with 2 and 3 benzene rings in NHP, most other PAHs showed a unimodal distribution pattern with the peak at 0.56–1.0 µm in both periods, which was caused by PAH emission sources. The PAH-related climate forcing was mainly caused by the solar radiation absorptions at ∼325 (∼330) nm and ∼365 nm. In general, the absorption intensities were higher in HP than NHP. The absorption intensity in the particle size range of 0.56–1.0 µm was the highest, and benzo[ e ]pyrene was the dominant contributor. In colder periods in HP, higher PAH concentrations caused more intensive PAH-related climate forcing. This study provided new insights for pollution characteristics and absorption spectra of size-resolved PAHs in atmospheric particles, which will be useful for better understanding PAH-related climate forcing. [Display omitted] • Pollution characteristics and absorption spectra of size-resolved PAHs were studied. • Most PAHs showed a unimodal distribution pattern with the peak at 0.56-1.0 µm. • PAH-related climate forcing was mainly occurred at ∼325 (∼330) and ∼365 nm. • The absorption intensity of solar radiation in HP was higher than that in NHP. • More intensive climate forcing caused by PAHs occurred in colder periods. [ABSTRACT FROM AUTHOR]

A 1‐month field campaign (May 29–June 29, 2018) was conducted at a mountain site (862 m above sea level) on the Wudang Mountains in China. The particle number size distribution (3–400 nm), size‐resolved cloud condensation nuclei (CCN, at 0.2% and 0.8% SS), and nonrefractory PM1 chemical composition were measured, respectively. The occurrence of the three chosen new particle formation (NPF) events (June 4, 7, and 11) was facilitated by southwest or west winds with a speed of about 3–4 m s−1. The hygroscopicity parameter (κ) value of newly grown particles varied in a wide range (0.25–0.8) during the events, leading to large uncertainties (−98% to 38%) on the NCCN prediction compared to the campaign. During growth of the newly formed particles for the three events, condensation of sulfuric acid vapor accounts for 14%–42%, 2%–8%, and 3%–9%, respectively, indicating that organic vapors may play an important role in particle growth. For plume‐type events with rapid growth, the observed high CCN activity (i.e., June 7 event) may be explained by the contribution of amines and depression of surface tension in the presence of organic surfactants during particle growth. Our study demonstrates that the contribution of NPF to CCN concentration is modulated by many key factors including growth rate, hygroscopicity, concentrations of new particles and preexisting particles, and variation of those factors from one event to another leads to large uncertainties on the CCN prediction. Plain Language Summary: A 1‐month field experiment (May 29–June 29, 2018) was conducted at a mountain site (862 m above sea level) on the top of the Wudang Mountains in China. Several particle characteristics including particle sizes, chemical composition, and cloud condensation nuclei (CCN) were measured using advanced analytical instruments. During the campaign, events corresponding to a well‐known atmospheric phenomenon called new particle formation were observed and facilitated by southwest or west winds. New particles, once they are formed, can grow to CCN sizes to enhance cloud formation. Prediction of CCN concentration is subject to large uncertainties during particle formation events because of large variation of particle hygroscopicity. In the atmosphere, sulfuric acid, an important condensable gas, plays an important role in particle growth. However, in our study, sulfuric acid vapor contributes minor to particle growth compared to organic compounds. Our study concludes that contribution of new particles to CCN concentration was controlled by many factors and might vary substantially from one event to another. Key Points: Substantial variation of hygroscopicity leads to significant uncertainties in cloud condensation nuclei predictionContribution of new particle formation to cloud condensation nuclei concentration varies in a large range from one event to anotherThe growth rate, hygroscopicity, new particle concentration, and preexisting particles are the key factors of the cloud condensation nuclei contribution [ABSTRACT FROM AUTHOR]

Intense and frequent new particle formation (NPF) events have been observed in polluted urban environments, yet the dominant mechanisms are still under debate. To understand the key species and governing processes of NPF in polluted urban environments, we conducted comprehensive measurements in downtown Beijing during January–March, 2018. We performed detailed analyses on sulfuric acid cluster composition and budget, as well as the chemical and physical properties of oxidized organic molecules (OOMs). Our results demonstrate that the fast clustering of sulfuric acid (H2SO4) and base molecules triggered the NPF events, and OOMs further helped grow the newly formed particles toward climate‐ and health‐relevant sizes. This synergistic role of H2SO4, base species, and OOMs in NPF is likely representative of polluted urban environments where abundant H2SO4 and base species usually co‐exist, and OOMs are with moderately low volatility when produced under high NOx concentrations. Plain Language Summary: Atmospheric new particle formation (NPF) is a dominant source of atmospheric ultrafine particles worldwide. Those particles profoundly influence climate and human health. NPF includes two consecutive processes, that is, the formation of new particles (∼2 nm in diameter) and their subsequent growth to larger sizes. Extensive studies conducted in the laboratory and in forested areas have shown that many gaseous species can participate in NPF, such as sulfuric acid, ammonia, amines, and oxidize organic molecules. However, the actual roles of these vapors may vary significantly from location to location and are largely unclear in urban environments. Here, based on measurements of sulfuric acid, sulfuric acid clusters, and oxidize organic molecules, we demonstrate that sulfuric acid and base molecules were responsible for the initial formation of new particles during a wintertime field campaign in Beijing. The majority of oxidized organic molecules had a minor contribution to the formation of new particles but were crucial for particle growth above 2–3 nm to climate‐ and health‐relevant sizes. Key Points: Process‐level understanding of new particle formation (NPF) in wintertime Beijing was obtained based on measurement state‐of‐the‐art instrumentsThe analysis of sulfuric acid cluster composition and budget showed that sulfuric acid‐base clustering initiated NPFCondensable organic vapors were characterized and demonstrated to have a crucial influence on the growth of newly formed particles [ABSTRACT FROM AUTHOR]

We have developed an automated data analysis method for atmospheric particles using scanning transmission X-ray microscopy coupled with near edge X-ray fine structure spectroscopy (STXM/NEXAFS). This method is applied to complex internally mixed submicrometer particles containing organic and inorganic material. Several algorithms were developed to exploit NEXAFS spectral features in the energy range from 278 to 320 eV for quantitative mapping of the spatial distribution of elemental carbon, organic carbon, potassium, and noncarbonaceous elements in particles of mixed composition. This energy range encompasses the carbon K-edge and potassium L2 and L3 edges. STXM/NEXAFS maps of different chemical components were complemented with a subsequent analysis using elemental maps obtained by scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM/EDX). We demonstrate the application of the automated mapping algorithms for data analysis and the statistical classification of particles.

With the increase of particulate pollution in the atmosphere, it becomes extremely significant to understand the overall distribution characteristics of particulates and their adsorption of toxic gases for the source analysis and precise controlling of atmospheric particulate matters. The fractal theory was adopted to analyze particle sizes distribution characteristics in Xi'an city, China. Results showed the fractal dimension of particulate matters distribution ranged from 4.32-4.83, with an average fractal dimension of 4.54. A higher fractal dimension predicts a higher concentration of fine particles. Additionally the effects of outdoor temperature, humidity, and wind speed on the fractal dimension were also studied experimentally. [ABSTRACT FROM AUTHOR]

An analytical method was validated with two reference materials of polycyclic aromatic hydrocarbons in atmospheric particles. Standard reference materials (SRMs) were incorporated into the matrix of unexposed cut quartz filters. The methodology was previously designed and extraction of polycyclic aromatic hydrocarbons (PAHs) from fortified filters was based on a rapid low-cost method, for a low consumption of volume and time. The optimisation combined a low-volume Soxhlet apparatus used in hot Soxhlet mode with a quick clean-up by solid-phase extraction with special cartridges. The quantification of target compounds was performed by gas chromatography/mass spectroscopy in SIM mode. Temperatures of injector and oven program of the GC-MS were also optimised. Experimental variables of both systems were successfully optimised and validated, achieving a robust analytical methodology. [ABSTRACT FROM AUTHOR]

This study focuses on the water-soluble ion concentrations in the washing solution of leaves of different roadside tree species at three sites in Iran to estimate the ionic composition of the dry deposition of ambient air particulates. All considered water-soluble ion concentrations were significantly higher next to the roads with high traffic density compared to the reference site with low traffic density. The PCA results showed that Ca2+, Mg2+, N O 3 − and S O 4 2 − originated mainly from traffic activities and geological sources, and Na+, Cl−, K+ and F− from sea salts. In addition to sea salt, K+ and F− were also originated from anthropogenic sources i.e. industrial activities, biomass burning and fluorite mining. Moreover, the concentration of the water-soluble ions depended on species and site. C. lawsoniana had significantly higher ion concentrations in its leaf washing solution compared to L. japonicum and P. brutia which indicates C. lawsoniana is the most suitable species for accumulating of atmospheric dry deposition. From our results, it can be concluded that sites with similar traffic density can have different particle loads and water-soluble ion species, and that concentrations in leaf-washing solutions depend on site conditions and species-specific leaf surface characteristics. [ABSTRACT FROM AUTHOR]

Images captured in hazy or foggy weather conditions can be seriously degraded by scattering of atmospheric particles, which makes the objects and their features difficult to be identified by computer vision systems. In the past decades, image de‐hazing is used to remove the influence of weather factors and improve image visualisation in hazy scenes by providing easy image post‐processing towards human assistance systems benefit. In this study, the authors present a variational segmentation model equipped with de‐hazing constraint terms in a new coupled dehazing‐segmentation model. The proposed hybrid formulation not only recovers/restores the fog/haze degradation but at the same time segments image degraded object/objects by solving in this way the difficulties of simultaneously performed dehazing and segmentation pre/post‐processing. This combination takes into account the image structure boundaries and the image quality, leading in this way to a robust dehazing segmentation scheme. The advantages of the proposed method are the suitability of the model for grey and vector‐valued images, a small number of parameters involved, and a rather good speed of the algorithm. Experiments show that their approach outperforms the state‐of‐the‐art algorithms in terms of segmentation accuracy while avoiding a dehazing preprocessing which reflects an extended CPU time. [ABSTRACT FROM AUTHOR]

The pollution of phthalate esters (PAEs) remains an important issue in the world. Current studies mainly focused on atmospheric PAEs in urban area with strong anthropogenic activities, but there were no studies on PAEs in the ambient air around large natural lake. This paper focused on two sites around Lake Chaohu to investigate the monthly occurrence, composition and source of PAEs in the atmospheric particles around large shallow natural lake. New insights into atmospheric PAEs in large shallow natural lake and the overall fate of PAEs in lake ecosystem were given. The concentrations of the Σ 13 PAEs in atmospheric particles were at a significantly low level ranging from 2740 to 11,890 pg·m−3 and 2622 to 15,331 pg·m−3 in ZM (the lakeshore site) and HB (the downtown site), respectively. There were no statistically significant differences of PAEs between ZM and HB. The highest atmospheric PAE concentrations in August were likely related to the long-range transport from Guangdong Province. Di(2-ethylhexyl) phthalate (DEHP), diisobutyl phthalate (DIBP) and dibutyl phthalate (DBP) were the main PAE congeners. Temporally, DIBP and DBP had the highest fractions in winter and the lowest fractions in summer. It might be justified by the condensation of DIBP and DBP from gas phase to particulate phase at low temperature. Multimedia comparison of PAE profiles in Lake Choahu revealed that low molecular weight (LMW) congeners were transported mainly through water while high molecular weight (HMW) congeners were transported mainly through atmosphere. Unlabelled Image • First investigation of atmospheric PAEs in natural lake. • DEHP, DIBP and DBP were the main PAEs in atmospheric particles around Lake Chaohu. • Condensation of DIBP and DBP at low temperature may lead to their temporal variations. • The transport pathway for different PAE congeners was disparate. [ABSTRACT FROM AUTHOR]

This study presents a yearlong data set of 28 medium-chain functionalised carboxylic acids (C5 to C10) in atmospheric aerosol particles (PM10) from a German rural measurement station, which is analysed to obtain seasonal trends and evidences for possible sources of these rarely studied compounds. The analysed carboxylic acids were divided into four main groups: (I) functionalised aliphatic monocarboxylic acids, (II) functionalised aromatic monocarboxylic acids, (III) non-functionalised and functionalised aliphatic dicarboxylic acids, and (IV) aromatic dicarboxylic acids. A concentration maximum in summer was observed for aliphatic carboxylic acids, indicating mainly photochemical formation processes. For example, the highest mean summer concentrations were observed for 4-oxopentanoic acid (4.1 ng m−3) in group I and for adipic acid (10.3 ng m−3) in group III. In contrast, a concentration maximum in winter occurred for aromatic carboxylic acids, hinting at anthropogenic sources like residential heating. The highest mean winter concentrations were observed for 4-hydroxybenzoic acid (2.4 ng m−3) in group II and for phthalic acid (5.8 ng m−3) in group IV. For the annual mean concentrations, highest values were found for adipic acid and 4-oxopimelic acids with 7.8 ng m−3 and 6.1 ng m−3, respectively. The concentrations of oxodicarboxylic acids exceeded those of their corresponding unsubstituted form. Accordingly, straight-chain dicarboxylic acids might act as precursor compounds for their respective oxygenated forms. Similarly, unsubstituted monocarboxylic acids are possible precursors for functionalised aliphatic monocarboxylic acids. The present study contributes to the speciation of organic content on a molecular level of atmospheric particles, as well as giving hints for possible sources for these carboxylic acids. [ABSTRACT FROM AUTHOR]

The changes of particles and organic pollutants in indoor atmospheres as consequence of vaping with electronic cigarettes have been analyzed. Changes in the composition of volatile organic compounds (VOCs) in exhaled breath of non-smoking volunteers present in the vaping environments have also been studied. The exposure experiments involved non-vaping (n = 5) and vaping (n = 5) volunteers staying 12 h together in a room (54 m2) without external ventilation. The same experiment was repeated without vaping for comparison. Changes in the distributions of particles in the 8-400 nm range were observed, involving losses of nucleation-mode particles (below 20 nm) and increases of coagulation processes leading to larger size particles. In quantitative terms, vaping involved doubling the indoor concentrations of particles smaller than 10 μm, 5 μm, and 1 μm observed during no vaping. The increase of particle mass concentrations was probably produced from bulk ingredients of the e-liquid exhaled by the e-cigarette users. Black carbon concentrations in the indoor and outdoor air were similar in the presence and absence of electronic cigarette emissions. Changes in the qualitative composition of PAHs were observed when comparing vaping and non-vaping days. The nicotine concentrations were examined separately in the gas and in the particulate phases showing that most of the differences between both days were recorded in the former. The particulate phase should therefore be included in nicotine monitoring during vaping (and smoking). The concentration increases of nicotine and formaldehyde were small when compared with those described in other studies of indoor atmospheres or health regulatory thresholds. No significant changes were observed when comparing the concentrations of exhaled breath in vaping and no vaping days. Even the exhaled breath nicotine concentrations in both conditions were similar. As expected, toluene, xylenes, benzene, ethylbenzene, and naphthalene did not show increases in the vaping days since combustion was not involved. [ABSTRACT FROM AUTHOR]

Abstract To investigate the potential cancer risk resulting from exposure to air pollutants, polycyclic aromatic hydrocarbons (PAHs) bound to airborne particles (PM 2.5) were assessed in one outdoor environment and four indoor environments before and during the Spring Festival of 2015. The average total PAH concentration was site-dependent, and the concentration decreased before and during the Spring Festival. Fluoranthene (Flt) was the most commonly occurring among the 16 priority PAHs, and benzo(a)pyrene (BaP) accounted for the largest portion of the total carcinogenic potency of PAHs in PM 2.5. The average BaP levels, in both indoor and outdoor environments, considerably exceeded the maximum permissible risk level of 1 ng/m3. Hazard quotients were found to be much less than 1, indicating little risk in terms of non-carcinogenic effects. Carcinogenic health risks resulting from possible carcinogens were determined to be much less than 1.00E-06. According to the California and WHO reference protocol, using empty room data to estimate the carcinogenic health risk produced values that were 10% lower than those calculated using outdoor environmental data. Graphical abstract fx1 Highlights • Estimate spatial-temporal variation of PM 2.5 -bound PAHs during winter in a research center, especially for holiday effect. • Students are exposed to a varying degree to PAHs in different microenvironments. • The daily concentration of BaP exceeding the upper limit (2.5 ng/m3) of the Chinese NAAQS on all sampling days. • Excess inhalation cancer risk was estimated by using the reference from indoor environment in winter of northeast China. [ABSTRACT FROM AUTHOR]

Copyright of Research of Environmental Sciences is the property of Research of Environmental Sciences Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Road intersections have the potential to pose an additional exposure risk to surrounding dwellers or commuters; however, knowledge of fine-scale variations of traffic pollutants especially PM 2.5 and black carbon (BC) remains limited. To investigate them, we conducted a three-point synchronous observation at an intersection in Shanghai in winter and spring. Real-time monitors with one-minute intervals were used to obtain the pollutant and meteorological data while gasoline and diesel vehicle volumes were manually collected every five minutes. Observational results showed that the average PM 2.5 on the downwind roadside increased by approximately 9% in both seasons and that the average BC increased by 70% in winter and 97% in spring compared to those of the local background site. PM 2.5 displayed a similar diurnal variation among the three sites at the intersection, but in contrast to PM 2.5 , the BC variation was more strongly correlated to the diurnal traffic cycle. Generalized additive models further identified the background variation as the major contributor to the variations in both pollutants at the intersection, explaining 77–99% and 33–43% of the variance in ln ( P M 2.5 ) and ln ( B C ) , respectively. Air pressure and solar radiation were the next top determinants of pollutant variations. Relative humidity combined with air temperature in winter and with dew-point temperature in spring also had a significant impact. Roadside BC was sensitive to traffic from the windward direction, while PM 2.5 was mostly influenced by the external pollution driven by westerly winds. In contrast to gasoline vehicles, diesel vehicles were verified to provide an appreciable contribution of approximately 9% to roadside BC variations in spring. [ABSTRACT FROM AUTHOR]

Long-term measurements of PM 2.5 mass concentrations and aerosol particle size distributions from 2008 to 2015, as well as hygroscopicity measurements conducted over one year (2008–2009) at Cabauw, The Netherlands, are compiled here in order to provide a comprehensive dataset for understanding the trends and annual variabilities of the atmospheric aerosol in the region. PM 2.5 concentrations have a mean value of 14.4 μg m -3 with standard deviation 2.1 μg m -3 , and exhibit an overall decreasing trend of −0.74 μg m -3 year -1 . The highest values are observed in winter and spring and are associated with a shallower boundary layer and lower precipitation, respectively, compared to the rest of the seasons. Number concentrations of particles smaller than 500 nm have a mean of 9.2 × 10 3 particles cm -3 and standard deviation 4.9 × 10 3 particles cm -3 , exhibiting an increasing trend between 2008 and 2011 and a decreasing trend from 2013 to 2015. The particle number concentrations exhibit highest values in spring and summer (despite the increased precipitation) due to the high occurrence of nucleation-mode particles, which most likely are formed elsewhere and are transported to the observation station. Particle hygroscopicity measurements show that, independently of the air mass origin, the particles are mostly externally mixed with the more hydrophobic mode having a mean hygroscopic parameter κ of 0.1 while for the more hydrophilic mode κ is 0.35. The hygroscopicity of the smaller particles investigated in this work (i.e., particles having diameters of 35 nm) appears to increase during the course of the nucleation events, reflecting a change in the chemical composition of the particles. [ABSTRACT FROM AUTHOR]

During the MILAGRO campaign, March 2006, eight-stage cut impactors were used to sample atmospheric particles at Tecámac (T1 supersite), towards the northeast edge of the Mexico City Metropolitan Area, collecting fresh local emissions and aged pollutants produced in Mexico City. Particle samples were analyzed to determine total mass concentrations of Ca2+, Mg2+, NH4+, K+, Cl−, SO42−, and NO3−. Average concentrations were 22.1 ± 7.2 μg m−3 for PM10 and 18.3 ± 6.2 μg m−3 for PM1.8. A good correlation between PM10 and PM1.8, without influence from wind patterns, indicates that local emissions are more important than the city’s pollution transported to the site, despite the fact that Tecámac is just 40 km away from Mexico City. A lack of diurnal patterns in the PM2.5/PM1.8 ratio supports this conclusion. The inorganic composition of particles suggests that vehicles, soil resuspension, and industries are the main pollutant sources. Finally, the particles were found to be neutralized, in agreement with observations in the Mexico City Metropolitan Area. [ABSTRACT FROM AUTHOR]

Copyright of Research of Environmental Sciences is the property of Research of Environmental Sciences Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To explore the polychlorinated biphenyl (PCB) pollution characteristics of atmospheric particles, influential factors, and dry deposition fluxes, 28 PCB congeners were examined over a 2-year period in the environment of an isolated island in Fujian Province. In 2006 and 2007, PCB concentrations ranged from 1.12 to 87.32 pg m-3 and ND (not detected) to 44.93 pg m-3, respectively, and were predominantly highly-chlorinated PCBs. The levels were much lower than those from industrial, urban, and rural areas, but slightly higher than those found in coastal areas of Europe and in the ocean. Obvious seasonal variations were found in the PCB levels, with high levels appearing in the winter, whereas low levels appeared in the summer, which indicated a significant positive correlation with the atmospheric particle mass level. The distribution pattern of the PCB concentration was largely affected by the meteorological conditions and total organic carbon (TOC) levels. Moreover, air mass originating from Northern China may be responsible for the higher PCB levels over Pingtan Island during the winter, and tracing the source of atmospheric particles by the stable carbon isotope suggested that the PBC levels may be influenced by coal combustion during the "heating season" of Northern China. The total dry deposition flux of the 28 PCBs on Pingtan Island was 3.94 ng m-2 d-1 and 2.94 ng m-2 d-1 in 2006 and 2007, respectively, and the average yearly input to the adjacent waters was 7531.2 g y-1. [ABSTRACT FROM AUTHOR]

Haze occurs frequently in many cities, and becomes the authors' great common concern. A distributed real‐time monitoring system for atmospheric particles has been designed, implemented and tested. The proposed system consists of a front‐end data wireless acquisition network, an embedded web server system, a central server and remote monitoring terminals. The front‐end data‐acquisition network is made up of mobile data‐acquisition nodes distributed in atmospheric particle monitoring areas which collect atmospheric particle data periodically. The data is transmitted by Jennet wireless network and sent to the Internet through the embedded web servers attached to the coordinator nodes via the serial ports. Only a common Internet browser is required for a remote user to check the atmospheric particle data. The central server is responsible for storing the pollution data for further usage of pollution analysis, evaluation and early warning. In this study, the PM1.0, PM2.5 and PM10 particle data were successfully collected, transmitted and checked by the monitoring system in Lanzhou, China. The results show that the designed system can meet the needs of functional requirements of atmospheric particle monitoring. [ABSTRACT FROM AUTHOR]

Copyright of Ambiente y Desarrollo is the property of Pontificia Universidad Javeriana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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.