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Numerous studies have shown negative health effects related to exposure to ambient particulate matter (PM), likely due to induced oxidative stress. In this study, we have examined ambient PM samples from Birr, a small (~5000 inhabitants) town in central Ireland, for their water-soluble DTT-based oxidative potential (OP_DTT) with a resolution of 6 h, together with online chemical characterization measurements, to assess the OP of organic aerosols, in particular from residential solid fuel burning. The OP_DTT normalized by the volume of sampled air shows a high variability, ranging from <0.1 to 3.8 nmol min−1 m−3, and a high correlation with PM mass. A lower variability was associated with the mass-normalized OP. Nevertheless, both tended to present higher values during night-time pollution episodes. Simple and multivariate linear regression approaches linked OP_DTT to residential solid fuel burning, and in particular to wood (~87%) and peat (~13%) combustion. The results of the present study show how residential solid fuel burning can have a severe impact on air quality, even in small towns, with potential negative health effects on the exposed population. [ABSTRACT FROM AUTHOR]

Sea salt (ss) aerosols in PM 2.5 are often quantified through source apportionment by applying sodium (Na + ) and chloride (Cl - ) as the markers, but both markers can be substantially emitted from anthropogenic sources. In this study, we differentiate ss from nonss (nss) portions of Na + and Cl - to better apportion PM 2.5 in a coastal tropical urban environment. Size-resolved ionic profiles accounting for Cl - depletion of aged ss were applied to 162-day measurements during 2012 and 2018-2019. Results show that the nss (likely anthropogenic) portions, on average, account for 50-80% of total Na + and Cl - in submicron aerosols (PM 1 ). This corresponds to up to 2.5 μg/m 3 of ss in submicron aerosols that can be ∼10 times overestimated if one attributes all Na + and Cl - in PM 1 to ss. Employing the newly speciated ss- and nss-portions of Na + and Cl - to source apportionment of urban PM 2.5 via positive matrix factorization uncovers a new source of transported anthropogenic emissions during the southwest monsoon, contributing to 12-15% of PM 2.5 . This increases anthropogenic PM 2.5 by ≥19% and reduces ss-related PM 2.5 by >30%. In addition to demonstrating Cl - depletion (aging) in submicron aerosols and quantifying ssNa + , nssNa + , ssCl - , as well as nssCl - therein, the refined PM 2.5 apportionment resolves new insights on PM 2.5 of anthropogenic origins in urban environments, useful to facilitate policy making.

Consideration is given to the problem of atomization of fine aerosols using atomizers of special designs that implement a cavitation regime. The formation of a fine aerosol is studied with the model of a pulse atomizer utilizing HEM energy and the model of an atomizer with a special nozzle to create counterflows. For these atomizers, the role of cavitation in obtaining a fine liquid aerosol is shown. A mathematical model is proposed which describes the processes of genesis of an aerosol cloud. Estimates of the critical pressure are obtained for the development of cavitation, the outflow velocity, and the resulting size of droplets as functions of the geometric parameters of the atomizers, the pressure in the structure, and the physicochemical properties of the liquid. Experimental investigations of the dispersion and concentration of aerosol particles are carried out using optical methods of measurement. Results of measuring the dispersion parameters of an aerosol in the process of cavitation atomization of liquids are presented. [ABSTRACT FROM AUTHOR]

Fine particulate matter (PM) is object of particular attention due to its health effects. It is currently regulated by adopting PM2.5 as an indicator to control anthropogenic combustion emissions. Therefore, it is crucial to collect aerosol samples representative of such sources, without including PM from natural sources. Thus, a clean separation between coarse and fine mode aerosol should be set. With this purpose, aerosol size mass distribution was taken in the aerodynamic diameter range from 0.5 to 10 µm. In comparison with a base scenario, characterized by local pollution sources, three case studies were considered, involving desert dust advection, sea salt advection and forest fire aerosol from a remote area. In the base scenario, PM2.5 represented a suitable fine-mode indicator, whereas it was considerably affected by coarse PM in case of desert dust and sea salt aerosol advection. Such interference was considerably reduced by setting the fine/coarse separation at 1.0 µm. Such separation underrepresented fine PM from forest fire long-range transport, nonetheless in the case studies considered, PM1 represented the best indicator of fine aerosol since less affected by coarse natural sources. The data presented clearly support the results from other studies associating the health effects of PM2.5 to PM1, rather than to PM1–2.5. Overall, there is a need to reconsider PM2.5 as an indicator of fine atmospheric aerosol.

Results of experimental investigation of the evolution and precipitation of a cloud of pneumatically obtained aerosol particles in a closed space under the influence of external physical fields are presented. The precipitation is contributed to by imposing acoustic and electrostatic fields, which leads to an acceleration of the coagulation of fine-aerosol particles. A method of searching for the aerosol′s dispersion characteristics is proposed, which has been implemented in a laser measuring complex. Experimental dependences of the average volume–surface diameter and of the relative concentration of aerosol particles of a model aerosol (talc) on time are presented. [ABSTRACT FROM AUTHOR]

The relevance of the research is related to searching the efficient ways of deposition of fine aerosols to clean production rooms from dust and smoke. Development of methods of ensuring purity of air environment in production rooms are especially relevant in connection with the development of nanotechnologies as well as engineering chemistries, related to possible emissions of harmful and dangerous dust. The main aim of the research is searching for optimum ways of deposition of fine aerosols comparing electrostatic and ultrasonic deposition of particles. Objects of the research are fine aerosols and ways of their deposition. Methods: mathematical modeling, optical methods of measurement of distribution function of particles by the sizes and concentration of aerosol particles using the laser measuring system LID2M and the Malvern Spraytec analyzer. Results. The authors have carried out the theoretical analysis of sedimentation rates of particles of fine aerosols (diameter of particles ~1-20 µm) in the presence of acoustic, electric field taking into account a drift in electric field, ultrasonic coagulation, and acoustic flows («sound wind»). The key mechanisms of particles deposition depending on their size are defined that allows proposing the optimum ways of deposition of fine aerosols in each range of particle sizes. The mathematical model of acoustic coagulation is based on an integral form of the equation of Smolukhovsky. The paper introduces the results of the experimental study of the model aerosol (NaCl) particles deposition with the reference diameter of particles about 6 µm by means of ultrasound and electrodeposition device. It is defined that application of these ways of deposition is essential (and it is approximately identical) and it accelerates considerably sedimentation of the model aerosol that corresponds to theoretical results. On the other hand, theoretical calculations predict that application of electrostatic way of deposition will be more effective in comparison with the ultrasonic one for aerosols with rather larger particles.

Finding an efficient way to eliminate fine dust (particle diameter of 1-15 µm) from a room can be a challenging problem. Acoustic radiation emitters are widely used to accelerate particle coagulation and sedimentation. In this study, we propose one more method for depositing harmful particles -- dispersion of electrostatically charged particles. These particles attract uncharged particles from the air and accelerate coagulation. The paper is devoted to a comparison of methods for the acoustic and electrostatic sedimentation of aerosols. The mathematical model for the coagulation of aerosols on the basis of Smoluchowski's equation is proposed in the options corresponding to acoustic and electrostatic coagulation. A number of conclusions about the most effective conditions of sedimentation were made on the basis of the analysis of a kernel type of Smoluchowski's integral equation. The results of the experiments on acoustic and electrostatic sedimentation of the model aerosol media (coal dust) are given. The results of the calculations according to the mathematical model of coagulation taking into account the proposed mechanisms for the sedimentation of aerosols in the acoustic field and electrostatic charging of particles are given. [ABSTRACT FROM AUTHOR]

Anhydrosugars including levoglucosan and mannosan are the most effective organic tracers for biomass burning aerosol in the atmosphere. In this study, to investigate the contribution of biomass burning emissions to the aerosol burden in the Pearl River Delta (PRD) region, China, 24-hour integrated PM2.5 samples were collected simultaneously at four locations, (i) Guangzhou (GZ), (ii) Zhaoqing (ZQ) in Guangdong province, (iii) Hok Tsui (HT) and (iv) Hong Kong Polytechnic University (PU) in Hong Kong, in four seasons between 2006 and 2007. Levoglucosan and mannosan, together with water-soluble inorganic ions and water-soluble organic carbon (WSOC), were determined to elucidate the seasonal and spatial variations in biomass burning contributions. The concentrations of levoglucosan and mannosan were on average 82.4±123 and 5.8±8.6 ng m−3, respectively. The WSOC concentrations ranged from 0.2 to 9.4 µg m−3, with an average of 2.1±1.6 µg m−3. The relative contributions of biomass burning emissions to OC were 33% in QZ, 12% in GZ, 4% at PU and 5% at HT, respectively, estimated by the measured levoglucosan to organic carbon ratio (LG/OC) relative to literature-derived LG/OC values. The contributions from biomass burning emissions were in general 1.7–2.8 times higher in winter than those in other seasons. Further, it was inferred from diagnostic tracer ratios that a significant fraction of biomass burning emissions was derived from burning of hard wood and likely also from field burning of agricultural residues, such as rice straw, in the PRD region. Our results highlight the contributions from biomass/biofuel burning activities on the regional aerosol budget in South China.

Results of measurements of the black carbon and fine aerosol content in Beijing and in a background region 150 km to the northeast of the capital of China are analyzed. The measurements have been carried out for many years, mainly in autumn periods. A regional decrease in the black carbon concentration has been found. The conclusion made in earlier works about the decrease in the relative contribution of soot aerosol, on average, with an increase in air turbidity has been corroborated. [ABSTRACT FROM AUTHOR]

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Filter-collected aerosol samples in the PM 1 and PM 10 fractions and particle number concentration were measured during experimental campaigns in a rural area near Bologna (Italy) in the periods 10–21 February 2014 and 19–30 May 2014. Ice nuclei particle (INP) concentrations measured off-line showed prevalently higher average values in the morning with respect to the afternoon, in the PM 1 fraction with respect to PM 1–10 (with the exception of the first campaign, at S w = 1.01), and at water saturation ratio S w = 1.01 with respect to S w = 0.96. The aerosol in the coarse size range (1–10 μm) contributed significantly to the total INP concentration. In the first campaign, the average INP concentration in the coarse fraction was 80% of the total in the morning and 74% in the afternoon, at S w = 1.01. In the second campaign, the contribution of the coarse size fraction to the INP number concentration was lower. On the whole, the results showed that the freezing activity of aerosol diameters larger than 1 μm needs to be measured to obtain the entire INP population. Sahara dust events (SDEs) took place during both campaigns, in the periods 17–20 February and 21–23 May 2014. Results show that the averaged particle number concentration was higher during SDE than during no-Saharan dust events. A low correlation between INP and total aerosol number concentration was generally measured, except for SDEs observed in February, in which the correlation coefficient between aerosol concentration in the coarse fraction and INP in the same range, at water supersaturation, was about 0.8. Precipitation events influenced the aerosol concentration. In the February campaign, lower values of INP and particle concentrations were measured in case of heavy rain events. During the May campaign, an average number concentration of the aerosol in the range 0.5–10 μm was slightly higher than on days when no precipitation was measured, the rainfall intensity being low. Only in a few cases did we note a sharp drop in INP in the PM 10 fraction at S w = 1.01 (26 May, 8 a.m. and 1 p.m.; 27 May, 1 p.m.). [ABSTRACT FROM AUTHOR]

Acoustic radiation sources are successfully applied to cleaning rooms from dust of fairly large particle sizes (ten micrometers and larger). The sedimentation of fine aerosols (particle diameter of 1-10 microns) is a more complicated challenge. The paper is devoted to the substantiation of the acoustic sedimentation method for such aerosols. On the basis of the mathematical model analysis for aerosol sedimentation by the acoustic field the mechanisms of this process have been determined and include the particle coagulation acceleration and radiation pressure effect. The experimental results of the acoustic sedimentation of a model aerosol (NaCl) are shown. The calculation results according to the mathematical model for coagulation and sedimentation, on the basis of the Smolukhovsky's equation taking into account various mechanisms of aerosol sedimentation by sound depending on the particle sizes and sound intensity, are given. The necessity to use intensive sources of high-frequency sound has been confirmed, suggesting that these sources must be located above dust clouds. [ABSTRACT FROM AUTHOR]

The variability of ground-level concentrations of fine suspended particulate matter (PM 2.5 ) in the Northeastern United States is examined using observed PM 2.5 from multiple data networks together with output from the Modern-Era Retrospective Analysis for Research and Applications Aerosol Reanalysis (MERRAero). The long-term variations as well as the occurrence of short-term high-concentration episodes in the region are investigated for the period 1999–2013. This analysis shows that over this period there has been a significant decrease in summer-mean PM 2.5 . A decrease in the occurrence and magnitude of high-PM 2.5 events in the Northeastern U.S. region is also observed. The potential sources of PM 2.5 are analyzed using MERRAero aerosol optical depth for two of the main components of the pollutant: organic carbon and ammonium sulfate. The analysis indicates that high-PM 2.5 events in the Northeastern U.S. are, generally, the result of long range transport of smoke from large boreal wildfires, Midwestern industrial emissions, or a combination of both. There are roughly equal numbers of events due to natural or anthropogenic sources for the 2002–2012 period for this region. The events that have an anthropogenic source are characterized by a strong high pressure system in the Southern U.S. that cause aerosols to be advected from the Midwest into the Northeastern U.S. The meteorology related to wildfire events is more variable, consistent with the varied locations of the fires that cause aerosol events in the Northeastern U.S. [ABSTRACT FROM AUTHOR]

We analysed aerosol optical and physical properties in an urban environment (Kolkata) during winter monsoon pollution transport from nearby and far-off regions. Prevailing meteorological conditions, viz. low temperature and wind speed, and a strong downdraft of air mass, indicated weak dispersion and inhibition of vertical mixing of aerosols. Spectral features of WinMon aerosol optical depth (AOD) showed larger variability (0.68-1.13) in monthly mean AOD at short-wavelength (SW) channels (0.34-0.5 μm) compared to that (0.28-0.37) at long-wavelength (LW) channels (0.87-1.02 μm), thereby indicating sensitivity of WinMon AOD to fine aerosol constituents and the predominant contribution from fine aerosol constituents to WinMon AOD. WinMon AOD at 0.5 μm (AOD ) and Angstrom parameter ( α) were 0.68-0.82 and 1.14-1.32, respectively, with their highest value in December. Consistent with inference from spectral features of AOD, surface aerosol loading was primarily constituted of fine aerosols (size 0.23-3 μm) which was 60-70 % of aerosol 10- μm (size 0.23-10 μm) concentration. Three distinct modes of aerosol distribution were obtained, with the highest WinMon concentration at a mass median diameter (MMD) of 0.3 μm during December, thereby indicating characteristics of primary contribution related to anthropogenic pollutants that were inferred to be mostly due to contribution from air mass originating in nearby region having predominant emissions from biofuel and fossil fuel combustion. A relatively higher contribution from aerosols in the upper atmospheric layers than at the surface to WinMon AOD was inferred during February compared to other months and was attributed to predominant contribution from open burning emissions arising from nearby and far-off regions. A comparison of ground-based measurements with Moderate Resolution Imaging Spectroradiometer (MODIS) data showed an underestimation of MODIS AOD and α values for most of the days. Discrepancy in relative distribution of fine and coarse mode of MODIS AOD was also inferred. [ABSTRACT FROM AUTHOR]

Anhydrosugars including levoglucosan and mannosan are the most effective organic tracers for biomass burning aerosol in the atmosphere. In this study, to investigate the contribution of biomass burning emissions to the aerosol burden in the Pearl River Delta (PRD) region, China, 24-hour integrated PM2.5 samples were collected simultaneously at four locations, (i) Guangzhou (GZ), (ii) Zhaoqing (ZQ) in Guangdong province, (iii) Hok Tsui (HT) and (iv) Hong Kong Polytechnic University (PU) in Hong Kong, in four seasons between 2006 and 2007. Levoglucosan and mannosan, together with water-soluble inorganic ions and water-soluble organic carbon (WSOC), were determined to elucidate the seasonal and spatial variations in biomass burning contributions. The concentrations of levoglucosan and mannosan were on average 82.4±123 and 5.8±8.6ng m-3, respectively. The WSOC concentrations ranged from 0.2 to 9.4µg m-3, with an average of 2.1±1.6µg m-3. The relative contributions of biomass burning emissions to OC were 33% in QZ, 12% in GZ, 4% at PU and 5% at HT, respectively, estimated by the measured levoglucosan to organic carbon ratio (LG/OC) relative to literature-derived LG/OC values. The contributions from biomass burning emissions were in general 1.7-2.8 times higher in winter than those in other seasons. Further, it was inferred from diagnostic tracer ratios that a significant fraction of biomass burning emissions was derived from burning of hard wood and likely also from field burning of agricultural residues, such as rice straw, in the PRD region. Our results highlight the contributions from biomass/biofuel burning activities on the regional aerosol budget in South China. [ABSTRACT FROM AUTHOR]

Isoprene is a substantial contributor to the global secondary organic aerosol (SOA) burden, with implications for public health and the climate system. The mechanism by which isoprene-derived SOA is formed and the influence of environmental conditions, however, remain unclear. We present evidence from controlled smog chamber experiments and field measurements that in the presence of high levels of nitrogen oxides (NOx = NO + NO2) typical of urban atmospheres, 2-methyloxirane-2-carboxylic acid (methacrylic acid epoxide, MAE) is a precursor to known isoprene-derived SOA tracers, and ultimately to SOA. We propose that MAE arises from decomposition of the OH adduct of methacryloylperoxynitrate (MPAN). This hypothesis is supported by the similarity of SOA constituents derived from MAE to those from photooxidation of isoprene, methacrolein, and MPAN under high-NOx conditions. Strong support is further derived from computational chemistry calculations and Community Multiscale Air Quality model simulations, yielding predictions consistent with field observations. Field measurements taken in Chapel Hill, North Carolina, considered along with the modeling results indicate the atmospheric significance and relevance of MAE chemistry across the United States, especially in urban areas heavily impacted by isoprene emissions. Identification of MAE implies a major role of atmospheric epoxides in forming SOA from isoprene photooxidation. Updating current atmospheric modeling frameworks with MAE chemistry could improve the way that SOA has been attributed to isoprene based on ambient tracer measurements, and lead to SOA parameterizations that better capture the dependency of yield on NOx. [ABSTRACT FROM AUTHOR]

Small-scale processes are taken to mean the disturbances of the atmospheric basic background which are caused by the thermal inhomogeneity of the underlying surface and under which one can neglect the effects of both centripetal and Coriolis accelerations. Slight disturbances suggest the use of linearized hydrothermodynamic equations of a weakly compressible atmosphere. Two models are considered. In one of the models, circulation over a weakly sloping barchan is analyzed using a refined model of mountain-valley circulation (the well-known Prandtl model). The other model, which is a model of a thermal spot in a geostrophic flow, can conditionally be called 'anticonvective.' This problem is solved using the method of universal functions for parabolic equations with variable coefficients. [ABSTRACT FROM AUTHOR]

Near real-time measurements of PM ionic compositions were performed at the summit of the highest mountain in the central-eastern plains in the spring and summer of 2007 in order to characterize aerosol composition and its interaction with clouds. The average concentrations of total water soluble ions were 27.5 and 36.7 μg m, accounting for 44% and 62% of the PM mass concentration in the spring and summer, respectively. A diurnal pattern of SO, NH and NO was observed in both campaigns and attributed to the upslope/downslope transport of air mass and the development of the planetary boundary layer (PBL). The average SO oxidation ratio (SOR) in summer was 57% (±27%), more than twice that in spring 24% (±16%); the fine nitrate oxidation ratio (NOR) was comparable in the two seasons (9 ± 6% and 11 ± 10% in summer and spring, respectively). This result indicates strong summertime production of sulfate aerosol. A principal component analysis shows that short-range and long-range transport of pollution, cloud processing, and crustal source were the main factors affecting the variability of the measured ions (and other trace gases and aerosols) at Mt. Tai. Strong indications of biomass burning were observed in summer. Cloud scavenging rates showed larger variations for different ions and in different cloud events. The elevated concentrations of the water soluble ions at Mt. Tai indicate serious aerosol pollution over the North China plain of eastern China. [ABSTRACT FROM AUTHOR]

Abstract: A novel wet electrostatic precipitator (WESP) is designed for effective control of fine aerosol from humid gases. It operates on the principle of unipolar particle charging in the corona discharge and particle precipitation under the field of their own space charge. The new precipitator is characterized by high gas velocity in the ionizing stage. Tests were carried out for gas with (NH4)2SO4, HCl and (NH4)Cl aerosol at particle number concentration up to 5·107#/cm3 and mass concentration 10–1000mg/Nm3. For test conditions one-field WESP ensures mass collection efficiency 90–97% and two-field electrostatic precipitator up to 99%. [Copyright &y& Elsevier]

This paper implements deep learning methods of recurrent neural networks and short-term memory models. Two kinds of time-series data were used: air pollutant factors, such as O3, SO2, and CO2 from 2017 to 2019, and meteorological factors such as temperature, humidity, wind direction, and wind speed. A trained model was used to predict air pollution within an eight-hour period. Correlation analysis was applied using Pearson and Spearman correlation coefficients. The KNN method was used to fill in the missing values to improve the generated model's accuracy. The average absolute error percentage value was used in the experiments to evaluate the model's performance. LSTM had the lowest RMSE value at 1.9 than the other models from the experiments. CNN had a significant RMSE value at 3.5, followed by Bi-LSTM at 2.5 and Bi-GRU at 2.7. In comparison, the RNN was slightly higher than LSTM at a 2.4 value. [ABSTRACT FROM AUTHOR]

Fine particulate matter (PM) is object of particular attention due to its health effects. It is currently regulated by adopting PM2.5 as an indicator to control anthropogenic combustion emissions. Therefore, it is crucial to collect aerosol samples representative of such sources, without including PM from natural sources. Thus, a clean separation between coarse and fine mode aerosol should be set. With this purpose, aerosol size mass distribution was taken in the aerodynamic diameter range from 0.5 to 10 µm. In comparison with a base scenario, characterized by local pollution sources, three case studies were considered, involving desert dust advection, sea salt advection and forest fire aerosol from a remote area. In the base scenario, PM2.5 represented a suitable fine-mode indicator, whereas it was considerably affected by coarse PM in case of desert dust and sea salt aerosol advection. Such interference was considerably reduced by setting the fine/coarse separation at 1.0 µm. Such separation underrepresented fine PM from forest fire long-range transport, nonetheless in the case studies considered, PM1 represented the best indicator of fine aerosol since less affected by coarse natural sources. The data presented clearly support the results from other studies associating the health effects of PM2.5 to PM1, rather than to PM1–2.5. Overall, there is a need to reconsider PM2.5 as an indicator of fine atmospheric aerosol. [ABSTRACT FROM AUTHOR]

Abstract: A period of intensive physical and chemical aerosol characterisation measurements was held over 5 days during July 2000 as part of the European SUB-AERO experiment.. Concurrent measurements were performed at the Finokalia remote coastal site on the island of Crete (Greece) and onboard the R/V “Aegaeon” which cruised in south part of the Aegean Sea northwards of Crete. The objective of the study was to investigate the spatial and temporal variability of microphysical parameters of the submicron aerosol and their dependence on airmass origin and chemical composition. The results reflect the submicron aerosol properties during airmass transport from the north including Europe and the Balkans and are in line with other studies on the aerosol properties of polluted continental air entering the marine boundary layer (MBL). Concentrations of submicron particulate matter (PM) mass were relatively higher at sea (20μgm−3) compared to the coastal site (16μgm−3). Concentrations of both organic carbon and sulphate, being the major water soluble component, were also higher at sea than at land. The high concentrations of ammonium and those of the water soluble organics, such as oxalate, can be attributed to emissions from mainland forest fires. The submicron aerosol number size distribution was unimodal with mobility mean diameters (d g) ranging from 98 to 144μm and standard deviations (σ g) from 1.56 to 1.9. Aerosol number concentrations at Finokalia were at least 50% lower especially when R/V Aegaeon sampled polluted air, but the modal parameters of the size distribution were very similar (d g: 111–120, σ g: 1.55–1.91). The surface MBL, under these conditions, was an aerosol rich environment where aerosol particles were transported both by the surface wind, advected from higher layers, chemically processed by interactions with gaseous precursors and physically altered by water vapour. The number to volume ratio for the submicrometer aerosol fraction reflected the effect of these mechanisms on the size distribution. [Copyright &y& Elsevier]

Particulate matter with diameters less than 2.5 μm (PM2.5) and ranging between 10 to 2.5 μm (PM10-2.5) were simultaneously collected at four air-quality monitoring stations in the Taichung area of central Taiwan during the period of February 12 to 22, 2004. Two different types of PM10 episodes, a nonlocal dust-storm episode and a local episode, were observed in the present study. High concentrations of coarse aerosols occurred during the dust-storm episode, whereas high concentrations of fine aerosols were present during the local episode. Relatively high levels of Na+, Mg2+, Ca2+, and Cl- in coarse aerosols were observed during the dust-storm episode. Very high concentrations of secondary aerosols ( NH4+, SO42-, and NO3-) in fine aerosols were observed during the local episode. The nitrate ion demonstrated the greatest increase in the ratios of ionic species to PM2.5 and ionic species to PM10-2.5 during the local episode. Significantly high ratios (0.444) of NO3- to NO2 in fine aerosols were present during the local episode, indicating that the relatively high formation rate of NO3- was one of the important factors leading to the increase of the NO3- to PM2.5 ratio during the local episode. Results also showed that an abundant quantity of fine ammonium nitrate was formed during the local episode, and chloride depletion probably was the major pathway to form coarse NaNO3 during this episode. [ABSTRACT FROM AUTHOR]

Abstract: The denuder/filter-pack sampling system has been used to simultaneously measure the daily concentrations of inorganic compounds of fine and coarse aerosol and related gases in Fukue Island, Japan, in three springs (March–April of 2000–2002). Gaseous nitric acid concentrations are low, and gas-to-total (gas+aerosol) fractions of nitrate are also low. The gas-to-total fraction of ammonium and the production of non-sea-salt (nss)-sulfate on coarse aerosol increase with dust loading. Total nitrate concentration correlates with both total ammonium concentration and total aerosol nss-sulfate concentration, although these species are differently partitioned among the gas and fine- and coarse-aerosol phases. In some dust events, there is a time lag between an increase in nss-sulfate concentration and an increase in dust loading. Trajectory analysis shows that one of the dust events with a time lag is composed of nss-sulfate from the east affected by volcanic plumes and dust from the northwest passing over the loess areas in the Asian continent. [Copyright &y& Elsevier]

Limits of detection (LODs) for aerosol samples collected using PIXE International cascade impactors, were improved approximately 50% after reducing the cross-sectional area of the analytical beam based on results obtained from microscope photographs of aerosol deposits. Improvements in LODs were most noticeable for selected elements collected on the smaller stages of the impactor (stages 1–3). [Copyright &y& Elsevier]

A year-round observation of the free amino acids (FAA) and combined amino acids (CAA) in coarse and fine aerosols were conducted at an urban site in Japan. The averaged concentrations of the total FAA and total CAA measured in this study were 149.9 and 237.6 pmolN m−3, respectively, in coarse aerosols, and 177.9 and 562.2 pmolN m−3, respectively, in fine aerosols. The concentrations of the total CAA were higher than those of the total FAA in both mode ranges. The CAA were mainly partitioned into the fine-mode range, whereas the FAA were contained in both mode ranges with a similar concentration level. Only 8.1% of the water-soluble organic nitrogen (WSON) in fine aerosols was explained by these amino acids, although a significant contribution (26.4%) of them to the WSON was found in coarse aerosols. Correlation and factor analyses including these amino acids and other chemical species in the aerosols and gas phase were conducted to discuss potential sources of these amino acids. Plant debris and their associated materials, sea-salt, and Asian dust particles would be important potential sources of the coarse-mode FAA. The most dominant FAA in coarse aerosols was serine that is considered to be derived from sea-salt and Asian dust particles, whereas the other major FAA in coarse aerosols would be from plant debris and associated materials. The coarse-mode CAA can be also considered to be mainly from plant debris and associated materials. Glutamic acid and aspartic acid were dominant in the coarse-mode CAA, and estimated to be from these sources. Significant parts of the fine-mode FAA would be derived from the photochemical aging of the fine-mode CAA in polluted air masses from the Asian continent. Glycine and arginine were dominant in the fine-mode FAA, and estimated to be from the photochemical aging process. The fine-mode CAA is considered to be mainly from both the fossil fuel and biomass burning particles from both the Asian continental and local sources. Glutamic acid and glycine were dominant in the fine-mode CAA, and would be mainly from these sources, especially the Asian continental sources. Serine that is the most dominant compound in the fine-mode CAA, however, is considered to be derived from other unidentified sources. • Plant debris, sea-salt, and Asian dust are important sources of the coarse-mode FAA. • The coarse-mode CAA is mainly derived from plant debris and associated materials. • The fine-mode FAA is mainly derived from the photochemical aging of the CAA. • The fine-mode CAA is mainly derived from both the fossil fuel and biomass burning. [ABSTRACT FROM AUTHOR]