Concentration Of Aerosol Particles Research Articles

Turbulent fluxes of aerosol and heat in a desertified area during intermittent emission of dust aerosol

Based on fluctuations measurement results in the components of wind speed, air temperature and concentration of aerosol particles on a desertified area in the Astrakhan region under conditions of intermittent emission of dust aerosol, vertical turbulent fluxes of dust aerosol and heat were determined. Using spectral analysis, the temporal variability of the horizontal and vertical components of wind speed, air temperature and concentration of dust aerosol particles was characterized. It is shown that the intermittent emission of the dust aerosol is determined by low-frequency convective-induced variations in the horizontal component of wind speed when the threshold saltation speed is exceeded. Significant differences in the spatiotemporal variability of vertical heat transfer and dust aerosol were revealed. The 30-minute average values of heat fluxes (90–158 W/m2) and dust aerosol (7.2–27.5 cm–2cm–1), as well as the rate of heat removal (14–21 cm/s) and dust aerosol (10–16 cm/s).

How horizontal transport and turbulent mixing impact aerosol particle and precursor concentrations at a background site in the UAE

Abstract. The optical, physical, and chemical properties of aerosol particles have been previously studied in the United Arab Emirates (UAE), but there is still a gap in the knowledge of particle sources and in the horizontal and vertical transport of aerosol particles and their precursors in the area. To investigate how aerosol particle and SO2 concentrations at the surface responded to changes in horizontal and vertical transport, we used data from a 1-year measurement campaign at a background site where local sources of SO2 were expected to be minimal. The measurement campaign provided a combination of in situ measurements at the surface and the boundary layer evolution from vertical and horizontal wind profiles measured by a Doppler lidar. The diurnal structure of the boundary layer in the UAE was very similar from day to day, with a deep, well-mixed boundary layer during the day transitioning to a shallow nocturnal layer, with the maximum boundary layer height usually being reached around 14:00 local time. Both SO2 and nucleation-mode aerosol particle concentrations were elevated for surface winds coming from the east or western sectors. We attribute this to oil refineries located on the eastern and western coasts of the UAE. The concentrations of larger cloud condensation nuclei (CCN)-sized particles and their activation fraction did not show any clear dependence on wind direction, but the CCN number concentration showed some dependence on wind speed, with higher concentrations coinciding with the weakest surface winds. Peaks in SO2 concentrations were also observed despite low surface wind speeds and wind directions unfavourable for transport. However, winds aloft were much stronger, with wind speeds of 10 m s−1 at 1 km common at night and wind directions favourable for transport; surface-measured concentrations increased rapidly once these particular layers started to be entrained into the growing boundary layer, even if the surface wind direction was from a clean sector. These conditions also displayed higher nucleation-mode aerosol particle concentrations, i.e. new particle formation events occurring due to the increase in the gaseous precursor.

Evaluation of different computational methods for numerical simulation of aerosol distribution in the operating room

In traditional operating rooms, controlling the concentration of aerosol particles has been necessary to ensure surgical safety. The COVID-19 pandemic has further emphasized the need for protecting medical staff in operating rooms, thereby increasing the focus on aerosol concentrations. Accurate simulation calculations of aerosol concentration and distribution play a crucial role in evaluating these concentrations and the associated risk of exposure. This study aims to assess the distribution of aerosols within an operating room by employing four different calculation methods and comparing them with experimental data. These methods included two turbulence models - Reynolds Averaged Navier Stokes (RANS) and Large Eddy Simulation (LES)-combined with two different aerosol transmission calculation models -Lagrangian and Eulerian. The findings indicate that the LES model yields a more accurate representation of the flow field, whereas no significant differences were observed among the four methods when it came to calculating aerosol concentrations. However, Eulerian-based methods exhibited superior continuity in the results. The errors of the four methods were greater than 50 % at Class II sampling locations and less than 50 % at Class III sampling locations. Consequently, this study serves as a scientific reference for selecting appropriate numerical simulation methods to predict aerosol concentration and distribution in operating rooms.

Measurement of Aerosol Particles from Vibrated Lab Coats.

A study was conducted to measure aerosol particles emitted from laboratory coats (lab coats) under vibration, comparing them with a suit and a shirt. This study focused on particles ranging from 0.3 μm to >10 μm. Experimental results showed that lab coat vibration increased particles >5 μm while reducing submicron particles. The lab coat (old and used) exhibited greater particle concentration variations under vibration compared to those using the new lab coat or the shirt. Contrastingly, the suit under vibration did not significantly affect particle concentrations. These findings highlight the impact of lab coat vibration on aerosol particle concentrations in the surrounding air, which is important for work environments.

Exploring the tendency of Brownian agglomeration in polydispersed systems of solid atmospheric aerosols

Recent extensive research has focused on atmospheric aerosol systems, driven by their far-reaching implications for climate and public health, with a goal to identify optimal air quality management practices. This study employs Langevin dynamics to investigate the impact of size distribution and concentration of submicrometer solid aerosol particles on Brownian agglomeration tendencies within an isothermal, hydrostatically balanced atmosphere. To accomplish this, a Langevin dynamic model is devised, and parameters are carefully determined to ensure numerical integration precision, stability, and efficiency. Using this model, we numerically simulate the average agglomeration nucleus and overall agglomeration rate within the system while considering variations in the standard deviation of size distribution and volume fraction of aerosol particles.

Unveiling respiratory health risks: PCDD/Fs adhering to particulate matter (PM10 and PM2.5) in Bien Hoa City, Dong Nai, Vietnam

This study investigates the concentrations of atmospheric aerosol particles (PM, including PM2.5 and PM10), as well as the presence and distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in ambient air in Bien Hoa City (Dong Nai province, Vietnam) during the dry and rainy seasons in 2023. The concentrations of 7 PCDDs and 10 PCDFs congeners in PM10 or PM2.5 were determined using gas chromatography-mass spectrometry (GC-MS). The results show that the concentration of PM10 and PM2.5 were 54.7 ± 9.4 µg/m3, 65.3 ± 7.6 µg/m3, and 39.6 ± 7.9 µg/m3, 58.9 ± 12.6 µg/m3, in the rainy season and dry season, respectively. This reveals that while only PM2.5 concentration levels in the dry seasonexceed national ambient air quality standards, but all of PM2.5 concentration levels consistently exceeded WHO guidelines. The study highlights the dominance of PM2.5 and its adverse health implications, as evidenced by the PM2.5/PM10 ratio (0.74 and 0.85 for the rainy and dry seasons, respectively) and its association with worse air quality. Analysis of PCDD/Fs concentrations in PM samples demonstrates their comparable levels in both seasons, with OCDD being the most abundant species. Furthermore, the study estimates the toxic equivalency (TEQ) of PCDD/Fs and assesses health risks, revealing a potentially high cancer risk from exposure to these pollutants, particularly PM2.5 under WHO2005-TEQ. Several PCDD/Fs- WHO2005-TEQ congeners exhibit higher concentration levels in PM2.5 compared to PM10, suggesting differential particulate matter dynamics and potential environmental implications. These findings underscore the urgent need for mitigation strategies to alleviate air pollution and reduce associated health risks in the dioxin hotspot of Vietnam.

Assessment of Atmospheric Particles Flux Variation on the Different Underlying Surfaces (Grasslands and Forest) in the Lake Baikal Region

In this study, the new data of experimental studies of the atmospheric particulate matter (PM) on the south-eastern coast of Lake Baikal (station Boyarsky) were analyzed in summer 2021. High-altitude measuring sites were arranged in the forest massif (mast, 16 m) and above the meadow vegetation (mast, 30 m). By the Giardina M. model and based on the measurements data the calculations of the deposition flux density of aerosol particles on forest and meadow vegetation were made. Our preliminary results of prediction obtained by Giardina M. model good agrees with measured dry deposition velocities across particle sizes. In the forest, the mass concentration of aerosol particles differs slightly from the mass concentrations in the grasslands and is equal on average 7.9 × 10−3 mg m−3 for the size particles below 200 nm (PM0.2) and 6.7 × 10−4 mg m−3 for particles in the size range from 0.2 to 10 μm (PM0.2–10). However, we found that mass flux density of aerosol particle is almost 4.8 times higher under forest canopy than in meadow vegetation. In addition, the leaf area index (LAI), which characterize the effective area of particle deposition, is also significantly higher in the tree canopy (5.6) compared to the grassland vegetation (2.4).

Air Composition over the Russian Arctic–4: Atmospheric Aerosols

This work presents the analysis of the spatial distribution of number concentration, size distribution, and chemical composition of aerosol particles measured for the first time over the seas of the Russian Arctic. Various types of vertical distribution of the number concentration were recorded, characteristic of both coastal marine and continental areas. Most of them turned out to be of the continental type. Attention is also drawn to the almost complete absence of coarse particles above 2–3 km over all seas. The chemical composition of the Arctic aerosol at altitudes of both 200 m and 5000 m contains ions that can be referred to as both marine and continental. The identifiable carbon- and salt-free elemental part of the aerosol over the Arctic is 3–4 times larger than that of ions. Over all seas and at both altitudes, the Arctic aerosols mainly contain elements of terrigenous origin – Al, Cu, Fe, and Si. Over almost all seas, except the Barents Sea, Si is dominant in the elemental composition of the aerosol, its contribution over the Chukchi Sea reaching 85%. The analysis of backward trajectories showed that in all cases considered, whether the aerosol was formed over the continent or sea, air trajectories passed both over sea and over land. In this case, the formed particles could be enriched with additional ions and elements along their pathway. This work completes a cycle of the papers, devoted to studying air composition, which was carried out over the seas of the Russian Arctic in September 2020. Our results can be used to model the atmospheric processes occurring in the Arctic under the conditions of changing climate.

Quantitative evaluation of the impact of indoor relative humidity on deposition of aerosols generated during tooth grinding in a real-world clinical setting.

Exposure to aerosol particles generated from tooth grinding has a negative impact on the health of dental personnel. The aim of this study was to quantitatively analyze the impact of indoor relative humidity (IRH) on the deposition of these suspended particles in a well-controlled dental environment. In this study, a humidity control system was employed to effectively regulate and maintain indoor relative humidity (IRH). A novel computer-assisted numerical control system was developed to pre-treat the molar specimens, and accurately simulate clinical tooth grinding procedures. Each procedure was performed in triplicate, with an online real-time particle counter (ORPC; TR-8301, TongrenCo.) measuring aerosol production. All testing devices were controlled remotely. The data obtained were statistically analyzed using descriptive statistics and non-parametric tests (Kruskal-Wallis/ Dunn's post hoc test with Bonferroni correction, p < 0.05). The findings showed that with increasing IRH, the maximum peak concentration of aerosol particles decreased by 397% from 6.51 × 107 particles/m3 at 30% to 1.64 × 107 particles/m3 at 80%. The Kruskal-Wallis test results indicated a statistically significant effect of IRH on the aerosol increment (p < 0.05). Increasing the IRH level can effectively promote the deposition of aerosol particles, with a return to baseline within 15min after reaching 60% or above. Our study suggested that maintaining IRH above 70% during the cleaning process, allowing natural recovery to ambient humidity levels within 15min after cleaning, and taking basic precautions, may lead to an adequate reduction in the possible health risks of aerosol contamination.

The impact of aerosols and model grid spacing on a supercell storm from Swabian MOSES 2021

AbstractThe supercell storm that occurred in southwestern Germany on June 23, 2021, had an exceptionally long lifetime of 7.5 hr, travelled a distance of nearly 190 km, and produced large amounts of hail. During that summer, the Swabian MOSES field campaign was held in that area, and several hydro‐meteorological measurements are available, as the storm passed directly over the main observation site. We present hindcasts of this event with the Icosahedral Non‐hydrostatic model using two horizontal grid spacings (i.e., 2 km, 1 km) with a single‐moment and an advanced double‐moment microphysics scheme. Numerical results show that all 2 km model realizations do not simulate convective precipitation at the correct location and time. For the 1 km grid spacing, changes in aerosol concentration resulted in large changes in convective precipitation. Only the 1 km run assuming a low cloud condensation nuclei (CCNs) concentration is able to realistically capture the storm, whereas no supercell is simulated in the more polluted scenarios. Observed aerosol particle concentrations indicate that CCNs values were the lowest of the month, which suggests that the low aerosol concentration is a reasonable assumption. The thermodynamic structure of the pre‐convective environment, as well as other observations, showed the best agreement to this model run as well, indicating that the good representation of the supercell was obtained for the right reason. The automatic tracking of individual clouds revealed that more convective cells with longer lifetimes are simulated at finer resolution. We also find a negative aerosol–precipitation effect that is not only due to a reduced collision–coalescence process, but also to weaker cold‐rain processes. These findings demonstrate the benefits of using an aerosol‐aware double‐moment microphysics scheme for convective‐scale predictability and that the use of different CCNs concentrations can determine whether a supercell is successfully simulated or not.

Radon and Its Short-Lived Products in Indoor Air: Present Status and Perspectives

Initially, basic equations are given to express the activity concentrations and concentrations of potential α-energies of radon (222Rn) and thoron (220Tn) and their short-lived products in indoor air. The appearance of short-lived products as a radioactive aerosol is shown, and the fraction of the unattached products is particularly exposed, a key datum in radon dosimetry. This fundamental part is followed by giving the sources of radon and thoron indoors, and thus, their products, and displaying the dependence of their levels on the ground characteristics, building material and practice, and living–working habits of residents. Substantial hourly, daily, and seasonal changes in their activity concentrations are reviewed, as influenced by meteorological parameters (air temperature, pressure, humidity, and wind speed) and human activity (either by ventilation, air conditioning and air filtration, or by generating aerosol particles). The role of the aerosol particle concentration and their size distribution in the dynamics of radon products in indoor air has been elucidated, focusing on the fraction of unattached products. Intensifying combined monitoring of radon short-lived products and background aerosol would improve radon dosimetry approaches in field and laboratory experiments. A profound knowledge of the influence of meteorological parameters and human activities on the dynamics of the behaviour of radon and thoron accompanied by their products in the air is a prerequisite to managing sustainable indoor air quality and human health.

Low-Cost Sensor System for Air Purification Process Evaluation.

With the development of civilisation, the awareness of the impact of versatile aerosol particles on human health and the environment is growing. New advanced materials and techniques are needed to purify the air to reduce this impact. This brings the necessity of fast and low-cost devices to evaluate the air quality from particulate and gaseous impurities, especially in a place where gas chromatography (GC) techniques are unavailable. Small portable and low-cost systems may work separately or be incorporated into devices responsible for air-cleaning processes, such as filters, smoke adsorbers, or plasma air cleaners. Given the above, this study proposes utilising a self-assembled low-cost system to evaluate air quality, which can be used in many outdoor and indoor applications. ESP32 boards with the wireless communication protocol ESP-NOW were used as the framework of the system. The concentration of aerosol particles was measured using Alphasense sensors. The concentrations of the following gases were measured: NO2, SO2, O3, CO, CO2, and H2S. The system was used to evaluate the quality of air containing tobacco smoke after passing through an actual DBD plasma reactor where the purification occurred. A high amount of reduction in aerosol particles and a reduction in the SO2 concentration were detected. An increase in the NO2 concentration was seen as an undesirable effect. The aerosol particle measurements were compared with those using a professional device (GRIMM, Hamburg, Germany), which showed the same trends in aerosol particle behaviour. The obtained results are auspicious and are a step towards producing a low-cost, efficient system for evaluating air quality as well as indoor and outdoor conditions.

Variability of Concentration of Aerosol Particles, Polycyclic Aromatic Hydrocarbons, and Polychlorinated Biphenyls in the Atmosphere above the Surface of Lake Baikal

Variability of Concentration of Aerosol Particles, Polycyclic Aromatic Hydrocarbons, and Polychlorinated Biphenyls in the Atmosphere above the Surface of Lake Baikal

Identification of exhaust stack sampling location of a research reactor considering ANSI/HPS N13.1-2011 mixing criteria using computational fluid dynamics

ABSTRACT Research Reactors have exhaust stacks that emit filtered radioactive gaseous waste into the atmosphere. In this research work, to check whether the radioactive gaseous waste met the requirements of ANSI/HPS N13.1–2011 mixing criteria, computational fluid dynamics (CFD) analysis was performed. According to ANSI criteria, Coefficient of Variance (COV) of velocity uniformity, flow angle, tracer gas, and aerosol particles concentration should be less than 20%. Therefore, the COV of the four parameters at different sampling positions along the stack height, with eight tracer gas and eight particles injection cases, were analyzed. The COV of velocity at 6 m height is 17.5% and flow cyclone is 9.8 degree. The results indicated that the 6 m height of the stack is enough for cyclone angle and COV of velocity to fulfill the ANSI mixing criteria. The COV of tracer gas concentration in one to eight injection cases is 10%, 4.8%, 7.5%, 17%, 2.5%, 6%, 13%, and 5% at 14 m stack height so the tracer gas also satisfied the standard mixing criteria in a concise length of 14 m because of the minimal difference in densities of tracer gas and air. However, due to their much higher density, aerosol particles took much longer to mix into the air. At 60 m stack height, the COV of aerosol particle concentration in one to eight injection cases is 14.8%, 18%, 8%, 12%, 11%, 15%, 15.5%, and 2%, respectively. As a result, when the stack height is set to 60 m, the COV of velocity, cyclone flow angle, tracer gas concentration, and aerosol particle concentration are found to meet the ANSI mixing criteria. Therefore, the minimum recommended height of the stack is proposed to be 60 m for the case under consideration.

Mitigation of Aerosol and Microbial Concentration in a Weaning Piggery by Spraying Nanobubble Ozone Water with an Ultrasonic Sprayer.

Enhancing biosecurity measures in livestock is an essential prerequisite for producing animal products with the highest levels of safety and quality. In Japan, 70% of the mortalities post-weaning are attributed to respiratory pathogens. The research has shown that microorganisms, including both viruses and bacteria, do not merely float in the air independently. Instead, they spread by adhering to aerosols. Therefore, improving the control of aerosol dissemination becomes a critical strategy for reducing pathogenic loads and boosting the overall efficiency of livestock production. This study focused on reducing concentrations of aerosol particles, airborne microbial concentrations, and airborne mass concentrations by spraying ozone solution with an ultrasonic sprayer. The experiments were conducted at a farm in Fukushima Prefecture, Japan, known for its integrated management system, overseeing a herd of 200 sows. Nanobubble ozone water particles were dispersed using an ultrasonic sprayer, which allowed the particles to remain airborne significantly longer than those dispersed using a standard nozzle, at a rate of 30 mL per weaning pig 49 days old, for a 10 min period. This procedure was followed by a 10 min pause, and the cycle was repeated for 17 days. Measurements included concentrations of airborne bacteria, aerosol mass, and aerosol particles. The findings demonstrated a substantial reduction in airborne microbial concentrations of Escherichia coli and Staphylococcus aureus in the treated area compared to the control, with reductions reaching a peak of 85.7% for E. coli and 69.5% for S. aureus. Aerosol particle sizes ranging from 0.3-0.5 µm, 0.5-1.0 µm, 1.0-2.0 µm, 2.0-5.0 µm, to 5.0-10.0 µm were monitored, with a notable decrease in concentrations among larger particles. The average aerosol mass concentration in the test area was over 50% lower than in the control area.

Quantitative assessment of nano-plastic aerosol particles emitted during machining of carbon fiber reinforced plastic

Focusing on the relatively unexplored presence of micro- and nano-plastic aerosol particles, this study quantitatively assessed the emission of nano-plastic particles during the machining of carbon fiber reinforced plastic (CFRP) in the working environment. Measurements of aerosol particles smaller than 1 µm in size were performed by aerosol mass spectrometry. The findings revealed that concentrations of carbonous aerosol particles (organic aerosol and refractory black carbon (rBC)) were higher during working hours than during non-working hours. Positive matrix factorization identified CFRP particles as a significant source, contributing an average of approximately 30% of concentration of carbonous aerosol particles during working hours. This source apportionment was corroborated by the presence of bisphenol A and F fragments, principal components of the epoxy resins used in CFRP, and was corroborated by similarities to the carbon cluster ion distribution observed in rBC during CFRP pipe-cutting operations. Further, the particle size distribution suggested the existence of plastic aerosol particles smaller than 100 nm. This study established the method to quantitatively distinguish nano-plastic aerosol particles from other aerosol particles in high temporal resolution and these techniques are useful for accurately assessing exposure to nano-plastic aerosol particles in working environments.

NUMERICAL THREE-DIMENSIONAL MODEL OF ULTRASONIC COAGULATION OF AEROSOL PARTICLES IN VORTEX ACOUSTIC STREAMING

Separation of highly dispersed systems with huge liquid-gas or liquid-solid interfaces is relevant for practical tasks of gas purification from the most highly dispersed and difficult-to-detect dispersed fraction PM2.5, and separation of nanoparticles (including their small agglomerates) in fine chemical technology processes. One of the most effective ways to separate highly dispersed systems with a large interface surface is to combine each of the closed subsurfaces (surfaces of individual dispersed particles) under the influence of hydrodynamic effects in the gas phase, arising both near the interface surfaces and at a considerable distance from them, due to the superposition of ultrasonic vibrations. Since the efficiency of ultrasonic coagulation decreases with a large distance between closed subsurfaces from each other in PM2.5 aerosol and the small size of these surfaces, it is necessary to create conditions for the emergence of new nonlinear effects that contribute to the local compaction of the dispersed fraction. In a resonant and significantly inhomogeneous ultrasonic field (with a scale of inhomogeneity on the order of the wavelength), vortex acoustic flows arise, which, due to inertial forces, locally compact the dispersed phase in the form of an increase in the concentration of aerosol particles. A numerical model of ultrasonic coagulation of PM2.5 aerosol particles in three-dimensional (3D) vortex acoustic streaming is proposed in this paper. The model is designed to identify the possibility of increasing the efficiency of ultrasonic coagulation in 3D streaming by virtue of the following mechanisms: (1) local increase in concentration caused by the inertial transfer of particles to the periphery of 3D vortices in the gas phase; (2) increase in the frequency of particle collisions due to 3D turbulent disturbances in ultrasonic fields; and (3) increase in productivity and ensuring uninterrupted implementation of the process in a flow mode owing to transfer of particles between the streamlines of the main vortices initiated by ultrasonic vibrations. The listed mechanisms for increasing the efficiency of coagulation in 3D streaming are taken into consideration by introducing two stream functions, considering turbulent chaotic disturbances of the flow resulting in dispersion of particle velocities. It was possible to establish based on numerical analysis of the model using the example of PM2.5 that laminar vortex flows begin to influence at sound pressure level from 160-165 dB, and turbulent disturbances make an additional contribution in the range of sound pressure levels from 140-170 dB. At the same time, as a result of 3D turbulent disturbances, the efficiency of coagulation reaches almost 100&amp;#37; at a sound pressure level 5 dB lower than with laminar flows (sound pressure amplitude, 3 times lower).

Study of particulate emissions when using special wires for underwater welding

The article describes the study to evaluate the emissions to atmospheric air of airborne nano- and microparticles generated during underwater welding in seawater from Ajax Bay (Sea of Japan) using special wires and coated electrodes. The most commonly used underwater industrial production processes were selected: semi-automatic (mechanized) underwater welding with a welding wire, manual welding with electrodes, and semi-automatic (mechanized) underwater cutting with a welding wire for cutting. An aerosol particle counter was used to determine the mass concentration of fine aerosol particles in the air of the working area above the aquarium. The highest number of suspended particles in the atmospheric air was observed in the process of underwater welding with a welding electrode. Comparing the welding wire and the welding electrode for underwater welding, it can be concluded that the welding wire is less dangerous for people, which is confirmed by the lower amount of suspended particles emitted into the atmospheric air during its use.

Characteristics of aerosol at the research base “Ice Cape Baranova” in 2018–2023

Atmospheric aerosol plays an important role in the processes of radiative transfers and mass exchange by different substances in the “continent–atmosphere–ocean” system. In this paper we discuss the results of a five-year measurement cycle of the atmospheric aerosol characteristics at the polar station “Ice base Cape Baranov”, located on the Bolshevik Island (the Severnaya Zemlya Archipelago). The set of the characteristics analyzed includes: the aerosol optical depth (AOD) of the atmosphere; the ground concentration of aerosol particles in the radius range of 0.15–5 microns; the content of the absorbing substance (soot) in the aerosol in the equivalent of elemental black carbon. The average values of the aerosol characteristics for the general measurement period (from April 2018 to May 2023) were: volumes of submicron and coarse aerosol particles 0.43 and 0.46 μm3/cm3, respectively; mass concentration of black carbon — 45.8 ng/m3; AOT of the atmosphere at a wavelength of 0.5 µm — 0.08; Angstrom selectivity exponent — 1.67. The average annual variation of aerosol and black carbon concentrations is characterized by a maximum in winter (January–March) and a minimum in summer (June–August). A comparison is made against the data from analogous measurements of aerosol characteristics at the polar station in Barentsburg (the Spitsbergen Archipelago) and against the data from model calculations, i. e., MERRA-2 reanalysis. A distinctive feature of the data in the Cape Baranov area is the low content of coarse aerosol — 1.7 less than in Barentsburg. There is agreement with the annual variation of black carbon concentrations at other polar stations, but the opposite nature of the seasonal variability of model (MERRA-2) concentrations: low values in winter and high values in summer. It is shown that the average spectral AODs of the atmosphere at the “Cape Baranov” are intermediate values between the data from polar stations in NyÅlesund and Barentsburg.

Intra-event evolution of elemental and ionic concentrations in wet deposition in an urban environment

Abstract. A measurement campaign was conducted in the Paris region, focusing on the evolution of chemical composition of wet deposition during rainfall events from sequential sampling. A total of eight rain events were documented and characterized by varying meteorological conditions, atmospheric dynamics, and aerosol particle concentrations representative of urban conditions and influenced by long-range mineral dust transport. The intra-event evolution of the chemical composition of wet deposition revealed the predominant role of meteorological parameters and local sources in the observed mass concentration variability. From selected case studies, the washout ratios (WRs) and scavenging coefficients were quantified by conducting simultaneous measurements of aerosol particle composition and wet deposition. The results highlighted a variability of the WR and scavenging coefficients depending on the rainfall rate and on the chemical species. Scavenging coefficients estimated from WR ranged from 5.4×10-8 to 1.1×10-5 s−1 for chemical elements, and they are within the range of values reported in the literature for 0.2–2 µm particle diameters. Our results pointed out that the scavenging coefficient increases with rainfall rate according to a power law, as previously shown in the literature, indicating a stronger removal of particles from the atmosphere with greater precipitation intensity. Quantitative analysis of the data allowed us to estimate the relative contributions of in-cloud scavenging (ICS) for selected rain events. The ICS relative contributions ranged on average from 23 % to 62 % depending on the rain events, and they varied according to the chemical species within the same rain event. This highlights the variability and complexity of the wet deposition process and the influence of specific factors on the contribution of ICS, such as aerosol particle size and hygroscopicity. Overall, this study highlights the variability of wet deposition and its chemical composition and the need to consider the specificities of each event to fully understand the underlying mechanisms.