The characterization of saccharidic compounds in atmospheric aerosols is important in order to retrieve information about organic carbon sources and their transport pathways through the atmosphere. ...In this study, composition and sources of saccharides in PM
10
were determined in a South Asian megacity (Faisalabad) during the year 2015 – 2016. PM
10
sampled on quartz filters was analyzed by anion exchange chromatography for the selected saccharidic compounds. The average PM
10
concentration was found to be 744 ± 392 μg m
−3
, exceeding the daily limits proposed by Pak-EPA (150 μg m
−3
), US-EPA (150 μg m
−3
), and WHO (50 μg m
−3
). The average total saccharidic concentration was found to be 2820 ± 2247 ng m
−3
. Among the different saccharidic categories, anhydrosugars were the most abundant in concentration followed by primary sugars and sugar alcohols. The correlation and principal component analysis indicated emissions from biomass combustion, soil suspensions from areas such as farmlands having high microorganism activity, and biogenic emissions such as airborne fungal spores and vegetation detritus as major sources of saccharides in the aerosol samples.
Cleaning workers are exposed to many risk factors, including handling of cleaning products. Epidemiological studies show that they have a high incidence of asthma and other respiratory symptoms. Some ...studies have indicated an even higher incidence of asthma in individuals using cleaning sprays regularly. It is known that sprays produce an aerosol that can expose the respiratory system to chemicals. Knowledge of the physical characteristics of the airborne particles, as well as the characteristics of the gas phase, is needed to determine how they affect the respiratory tract and why they cause airway symptoms. The aim of this study was to characterize the aerosols from seven different ready-to-use trigger cleaning sprays in terms of total airborne mass fraction, particle size distribution, and new particle formation from ozone reactions. An additional aim was to calculate the respiratory deposition fraction of the measured particles. The total airborne mass fraction was determined by comparing the mass deposited on the chamber wall with the mass emitted from the bottle during spraying. Particle number concentration and size distribution of the airborne particles were measured using an aerodynamic particle sizer and a fast aerosol mobility size spectrometer. The total airborne mass fraction was between 2.7% and 32.2% of the mass emitted from the bottle, depending on the product. Between 0.0001% and 0.01% of the total airborne mass fraction consisted of residual particles. However, these particles had a mass median aerodynamic diameter between 1.9 µm and 3.7 µm, constituting a total respiratory deposition of up to 77%. New particle formation in the presence of ozone was also shown to vary between 5,000 cm
−3
and 35,000 cm
−3
depending on the product, in the studied settings. These findings confirm that a substantial part (up to 1/3) of the mass sprayed from the bottle does not reach the intended surface. Thus, the use of cleaning sprays can result in chemical airway exposure, with particles in the relevant size range for both nasal and alveolar deposition.
Particulate matter (PM
10, PM
2.5) measurements were performed during the period 2003–2009 at the Akrotiri monitoring station (suburban/rural) on the island of Crete, Greece. Concurrent measurements ...of PM
10 size distribution/chemical composition were also performed at selected time intervals to determine the PM sources in the region and the factors controlling their levels. Using a beta radiation attenuation monitor, the mean PM
10 concentration during the measuring period (15.04.2003–31.12.2009) was equal to 36.1
±
9.5
μg/m
3, whereas the PM
2.5 concentration was equal to 23.6
±
5.8
μg/m
3. Back trajectories showed that the dominant air mass origin was from North and Northwest Europe but the intrusion of southern air masses lead to elevated PM concentrations due to Saharan dust events. The 24-h EU limit value of 50
μg/m
3 (PM
10) was exceeded approximately 13.5% during the measured period. Furthermore, the PM
10 mass size distribution of metals, ions and organic carbon/elemental carbon (OC/EC) was characterized using a 9-stage Andersen non-viable impactor and a gravimetric sequential PM
10 sampler during two selected periods. The mean PM
10 concentration during the first sampling period was equal to 28.3
±
12.4
μg/m
3 (10.08.2007–28.08.2007), whereas during the second sampling period (09.07.2008–19.07.2008) was 41.6
±
14.0
μg/m
3. The measurements showed a bimodal size distribution for the aerosol mass concentration. PM
2.1 accounted for 41.0% and 37.2% for PM
10 during the two periods respectively. Over the measurement campaigns ions dominated the PM
10 mass (50–80%) with the organic mass and metals comprising the major part of the rest. The OC concentration was equal to 2.3
±
1.2
μg/m
3, whereas the EC concentration was equal to 0.8
±
0.2
μg/m
3. Finally, black carbon concentrations were measured in August 2007 with an aethalometer. The mean daily value of black carbon was 0.69
±
0.22
μg/m
3. The measurements showed that the PM values measured at the station correspond to a background/rural station in the region and are in agreement with other measurements in the Eastern Mediterranean region.
► We examine aerosol levels and variability in conjunction with their sources and their chemical signatures. ► Size distribution aerosol data chemically resolved are examined showing a bimodal size distribution. ► Ions dominate the PM
10 mass with Organic mass and metals comprising the major part of the rest. ► The 24-h EU limit value of 50
μg/m
3 (PM
10) was exceeded approximately 13.5% during the measured period. ► It is the first study in this area where OC and EC were determined in the whole range of the aerosol size distribution.
A characterisation of the dust transported from North Africa deserts to the Cape Verde Islands, including particle size distribution, concentrations and optical properties, for a complete annual ...cycle (the year 2011), is presented and discussed. The present analysis includes annual simulations of the BSC-DREAM8b and the NMMB/BSC-Dust models, 1-yr of surface aerosol measurements performed within the scope of the CV-DUST Project, AERONET direct-sun observations, and back-trajectories. A seasonal intrusion of dust from North West Africa affects Cape Verde at surface levels from October till March when atmospheric concentrations in Praia are very high (PM10 observed concentrations reach hourly values up to 710 µg/m
3
). The air masses responsible for the highest aerosol concentrations in Cape Verde describe a path over the central Saharan desert area in Algeria, Mali and Mauritania before reaching the Atlantic Ocean. During summer, dust from North Africa is transported towards the region at higher altitudes, yielding to high aerosol optical depths. The BSC-DREAM8b and the NMMB/BSC-Dust models, which are for the first time evaluated for surface concentration and size distribution in Africa for an annual cycle, are able to reproduce the majority of the dust episodes. Results from NMMB/BSC-Dust are in better agreement with observed particulate matter concentrations and aerosol optical depth throughout the year. For this model, the comparison between observed and modelled PM10 daily averaged concentrations yielded a correlation coefficient of 0.77 and a 29.0 µg/m
3
'bias', while for BSC-DREAM8b the correlation coefficient was 0.63 and 'bias' 32.9 µg/m
3
. From this value, 12-14 µg/m
3
is due to the sea salt contribution, which is not considered by the model. In addition, the model does not take into account biomass-burning particles, secondary pollutants and local sources (i.e., resuspension). These results roughly allow for the establishment of a yearly contribution of 42% of dust from North African deserts for PM10 levels observed in Cape Verde.
An experimental set-up has been developed for the production and characterization of aerosols developed from RDDs (Radioactive Dispersion Devices, a.k.a. dirty bombs). Separate effects of ...temperature, materials and different atmospheres on the produced aerosols characteristics can be systematically studied. A laser heating technique is used to vaporize the sample, and aerosols are then generated mainly by nucleation/condensation of the formed vapour. Different collection systems have been developed, permitting the use of different substrates and consequently the application of different post-analysis techniques for aerosols characterization (SEM/EDX, RAMAN, ICP-MS). The set-up permits us to study the chemical processes acting in aerosol formation, thanks to the control of the experiments atmosphere and temperature. The set-up has been tested for different materials, such as ceramics, salts and metals, and proved to be feasible for the production, collection and post-analyses of aerosols. Moreover the set-up is placed in a glove box, and suitable for tests with radioactive and nuclear materials. In this paper the set-up will be described, focussing on the instrumentation applied, on the post-analysis techniques and on the experimental procedure. Finally also examples of the results obtained will be given.
The recently presented drop-on-demand (DOD) aerosol generator overcomes some of the drawbacks of pneumatic nebulization, as its aerosol is no longer generated by gas–liquid interaction. In the ...current study, an advanced imaging technique is presented, based on a CCD camera equipped with magnifying telecentric optics to allow for fast, automated and precise aerosol characterization as well as fundamental studies on the droplet generation processes by means of pseudo-cinematography.
The DOD aerosol generator is thoroughly characterized regarding its droplet size distribution, which shows few distinct populations rather than a continuous distribution. Other important figures, such as the Sauter diameter (D3,2) of 22μm and the span of 0.4 were also determined. Additionally, the influence of the electrical operation conditions of the dosing device on the aerosol generation process is described. The number and volume of the generated droplets were found to be very reproducible and user-variable, e.g. from 17 to 27μm (D3,2), within a span of 0.07–0.89. The performances of different setups of the DOD as liquid sample introduction system in ICP-MS are correlated to the respective achievable aerosol characteristics and are also compared to the performance of a state-of-the-art μ-flow nebulizer (EnyaMist). The DOD system allowed for improved sensitivity, but slightly elevated signal noise and overall comparable limits of detection. The results are critically discussed and future directions are outlined.
Further characterization of the drop-on-demand aerosol generator for sample introduction in atomic spectrometry. Display omitted
•Significantly improved ICP-MS sensitivity using the DOD vs. EnyaMist.•Comparable detection limits but slightly worse short-term precision.•Superior flexibility compared with conventional/miniaturized pneumatic nebulizers.•Electrical operation conditions of the DOD influence aerosol characteristics.•The ejected volume can be adjusted from 8 to 36pL per dosing event.
Vipava valley in Slovenia is a representative hot-spot for complex mixtures of different aerosol types of both anthropogenic and natural origin. Aerosol loading distributions and optical properties ...were investigated using a two-wavelength polarization Raman LiDAR, which provided extinction coefficient, backscatter coefficient, depolarization ratio, backscatter Ångström exponent and LiDAR ratio profiles. Two different representative meteorological situations were investigated to explore the possibility of identifying aerosol types present in the valley. In the first case, we investigated the effect of strong downslope (Bora) wind on aerosol structures and characteristics. In addition to observing Kelvin–Helmholtz instability above the valley, at the height of the adjacent mountain ridge, we found new evidence for Bora-induced processes which inject soil dust aerosols into the free troposphere up to twice the height of the planetary boundary layer (PBL). In the second case, we investigated aerosol properties and distributions in stable weather conditions. From the observed stratified vertical aerosol structure and specific optical properties of different layers we identified predominant aerosol types in these layers.
Methods for determining aerosol types in cases where chemical composition measurements are not available are useful for improved aerosol radiative forcing estimates. In this study, two aerosol ...characterization methods by Cazorla et al. (2013, https://doi.org/10.5194/acp-13-9337-2013; CA13) and Costabile et al. (2013, https://doi.org/10.5194/acp-13-2455-2013; CO13) using wavelength‐dependent particle absorption and scattering are used, to assess their applicability and examine their limitations. Long‐term ambient particle optical property and chemical composition (major inorganic ions and bulk carbon) measurements from the Maldives Climate Observatory Hanimaadhoo as well as concurrent air mass trajectories are utilized to test the classifications based on the determined absorption Ångström exponent, scattering Ångström exponent, and single scattering albedo. The resulting aerosol types from the CA13 method show a good qualitative agreement with the particle chemical composition and air mass origin. In general, the size differentiation using the scattering Ångström exponent works very well for both methods, while the composition identification depending mainly on the absorption Ångström exponent can result in aerosol misclassifications at Maldives Climate Observatory Hanimaadhoo. To broaden the applicability of the CA13 method, we suggest to include an underlying marine aerosol group in the classification scheme. The classification of the CO13 method is less clear, and its applicability is limited when it is extended to aerosols in this environment at ambient humidity.
Key Points
Optical aerosol classifications conform reasonable well with chemical measurements and air mass origin analysis
The extension of optical characterization methods to a remote marine site is limited due to strong aerosol mixing and humidification
An underlying sea spray category should be considered for optical aerosol characterization at sites with marine influence
Experimental tests have been performed to characterize the aerosols representative of radiological dispersion devices (RDDs, a.k.a. "dirty bombs") by applying to chosen surrogate compound rapid high ...temperature transients, vaporizing the sample and forming aerosols mainly by rapid cooling of the vapour. The materials, which were tested in their non-radioactive form, had been chosen from the radioactive sources widely used in industries and nuclear medicine applications, Co, CsCl, Ir and SrTiO
3
. Our analyses permitted the characterization of the inhalable fraction of the aerosols released, and the study of the influence of cladding materials on the aerosol release and on its characteristics.
PDF
