Coarse Aerosol Fractions Research Articles

Influenza A and B Viruses in Fine Aerosols of Exhaled Breath Samples from Patients in Tropical Singapore.

Influenza is a highly contagious respiratory illness that commonly causes outbreaks among human communities. Details about the exact nature of the droplets produced by human respiratory activities such as breathing, and their potential to carry and transmit influenza A and B viruses is still not fully understood. The objective of our study was to characterize and quantify influenza viral shedding in exhaled aerosols from natural patient breath, and to determine their viral infectivity among participants in a university cohort in tropical Singapore. Using the Gesundheit-II exhaled breath sampling apparatus, samples of exhaled breath of two aerosol size fractions ("coarse" > 5 µm and "fine" ≤ 5 µm) were collected and analyzed from 31 study participants, i.e., 24 with influenza A (including H1N1 and H3N2 subtypes) and 7 with influenza B (including Victoria and Yamagata lineages). Influenza viral copy number was quantified using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Infectivity of influenza virus in the fine particle fraction was determined by culturing in Madin-Darby canine kidney cells. Exhaled influenza virus RNA generation rates ranged from 9 to 1.67 × 105 and 10 to 1.24 × 104 influenza virus RNA copies per minute for the fine and coarse aerosol fractions, respectively. Compared to the coarse aerosol fractions, influenza A and B viruses were detected more frequently in the fine aerosol fractions that harbored 12-fold higher viral loads. Culturable virus was recovered from the fine aerosol fractions from 9 of the 31 subjects (29%). These findings constitute additional evidence to reiterate the important role of fine aerosols in influenza transmission and provide a baseline range of influenza virus RNA generation rates.

Detailed NMR analysis of water-soluble organic compounds in size-resolved particulate matter seasonally collected at a suburban site in Prague

The water-soluble organic compounds (WSOC) in size-resolved summer and winter aerosol collected in a Prague suburban area were analysed by 1H NMR spectroscopy. Advanced analysis of 1H NMR spectra − NMR aerosolomics − was applied, leading to the identification of 73 organic species in total. The compounds were classified into 9 chemical classes according to chemical nature, and possible aerosol sources were discussed, including an association of compounds across different classes according to common source or degradation pathway. A correlation between carbohydrates and trimethylglycine and choline was found in the coarse summer aerosol. Similar distribution profile was observed for several compounds associated to biomass burning in winter series. Multivariate statistical analysis revealed differences in chemical composition between both seasons and identified the main features of the fine and coarse aerosol matter. The group separation according to the season of sample collection was found mainly affected by levoglucosan while the content of carbohydrates in the coarse aerosol fractions impacted the clustering based on the particle size.

Air pollution in the Gobi Desert region: Analysis of dust‐storm events

AbstractAir pollutants in nine cities of the Gobi Desert region are examined in this study. Mean concentrations of PM2.5 and PM10, retrieved from ground‐based air quality monitoring stations, were 36.2 ± 23.7 and 97.3 ± 84.5 μg·m−3, respectively. The highest concentrations of pollutants were in spring and winter. This can be explained by wind‐borne dust in the spring and emissions from domestic sources during the winter heating season. The highest PM2.5 and PM10 concentrations were registered in a period of dust‐storm activity with values of 343 μg·m−3 and 1,642 μg·m−3. Generally, clean continental (CC) was the dominant aerosol type (73.9%), followed by mixed (MX) aerosol type (20.4%) with insignificant contribution of clean marine (CM) (2.1%), urban/industrial and biomass burning (UI/BB) (0.9%) and desert dust (DD) (2.7%) aerosol types. The various measures of pollution retrieved from AERONET stations, including aerosol optical depth (AOD), Ångström exponent (AE), asymmetry parameter (AP), single scattering albedo (SSA) and aerosol volume size distribution (AVSD), specify the content of coarse aerosol fractions in the period of dust activity. The aerosol radiative forcing at the bottom of the atmosphere (ARFBOA) and the top of the atmosphere (ARFTOA) during dust days were estimated to be −115.76 and −241.31 W·m−2, with a corresponding heating rate of 3.52 K·day−1. According to the backward and forward trajectories of air masses, the dust cloud moved to the east and southeast from the epicentre, affecting the eastern and the central parts of the country. This study may advise environmental policy, as it showed how controlling causes of pollution can improve air quality.

Seasonality of ship emission related atmospheric pollution over coastal and open waters of the North Sea

The seasonal changes of a large set of atmospheric pollutants (i.e., gases, water-soluble aerosols, metallic/elemental components and black carbon (BC) content) have been studied over the southern bight of the North Sea (the Belgian Continental Shelf) and the English Channel during several marine sampling campaigns, carried out in 2010–2011. A coastal research station at De Haan, Belgium was concurrently used as a background air monitoring site. Size-segregated aerosols (PM1, PM2.5-1, PM10-2.5) were analyzed for particulate mass, elemental content and water-soluble (ionic) compounds, while the equivalent BC content in PM10 was monitored with an Aethalometer. The results clearly demonstrated that the aerosols originating from ship exhaust emissions contributed mostly to fine fraction (PM1), and to a lesser extent to medium-sized fraction (PM2.5-1), whereas components of sea spray and of mineral/soil origin were dominating in the medium-size and coarse aerosol fractions. Looking at seasonal differences, more ship emission related components occurred in the fine and medium-sized PM during winter. Mineral aerosol components were more apparent in coarse PM and especially during the cold season, increased levels were noted. Similarly, higher concentrations of marine fine PM were found during winter, likely due to more extensive ship emissions and/or calm weather conditions. Gaseous pollutants (e.g., HNO2, HNO3, HCl, SO2, NH3) originating from exhaust fumes of ocean-going ships mostly reached the maximum levels in the cold season as well, thus supporting the more intense formation of secondary aerosols. The seasonal trends of total (inorganic) ionic species sampled on the open sea and at the coastal station were usually similar to those of the corresponding PM masses, peaking in the cold season. Sea salt bound fine sulfate and nitrate peaked in spring or the cold season for marine areas, whereas for the coastal site they clearly reached the maximum in the cold season. Ammonium-bound nitrates and sulfates in each PM fraction reached their peak air levels in the cold season over marine sites. Similar seasonal trends could be observed for the coastal station. The general tendency of aerosol distribution over the study areas was independent of the sampling site: the higher the aerosol mass on the open sea with ship traffic, the higher the suspended particulate mass sampled at the coast.

Spatial distribution and temporal variation of atmospheric pollution in the South Gobi Desert, China, during 2016-2019.

The rapid pace of economic growth and urbanization in China affects both large and small cities of the country, causing an increase of pollutant concentrations in the air. The South Gobi is one of the main deserts and semidesert regions of the country; therefore, the study of air pollution near the potential source of natural aerosols is of great importance. Data obtained in the period from 1 January 2016 to 31 December 2019 was used to analyze spatial-temporal characteristics of atmospheric pollutants (PM2.5, PM10, SO2, NO2, and CO) in eight cities. Total mean concentrations of PM2.5 and PM10 were 36.1 ± 21.1μg/m3 and 98.6 ± 108.7μg/m3. The occurrence rates of concentrations exceeding the Chinese National Ambient Air Quality Standard (CNAAQS) grade 1 and grade 2 were 40.1% and 5.4% for PM2.5 and 82.9% and 11.64% for PM10 in the region. Total concentrations of SO2, NO2, and CO did not exceed the CNAAQS standard and were 20.8 ± 23.6μg/m3, 22.6 ± 11.9μg/m3, and 0.72 ± 0.39mg/m3, respectively. The PM2.5 to PM10 ratio increased from 0.35 in spring to 0.46 in winter suggesting the predominance of coarse aerosol fractions in the atmosphere. Based on data on aerosol optical depth (AOD) and Ångström exponent (AE) ratio obtained from Moderate Resolution Imaging Spectroradiometer (MODIS), the predominant aerosol types in the region are Clean Сontinental and Mixed. Maximum concentrations of pollutants and the highest AOD values in the region air are observed in spring and winter. Results set forth in this article will be an important basis for further regional studies on air quality and distribution of sources.

Spatial analysis of aerosol optical depth obtained by air quality modelling and SEVIRI satellite observations over Portugal

The aim of this work is to explore the aerosol optical depth (AOD) data provided by different sources, namely satellite observations, air quality modelling and Aerosol Robotic Network (AERONET) observations, in order to improve characterisation of aerosol spatial distribution and to assess the contribution of the dust events on AOD over Portugal. Thus, the spatial and temporal variations of the AOD data were analysed for May 2011 taking into account the occurrence of mineral dust events. Satellite data obtained by Spinning Enhanced Visible and Infra-Red Imager (SEVIRI) instrument and air quality modelling results from the Comprehensive Air Quality Model (CAMx) over Portugal were explored. In this work, AOD values with a temporal resolution of 15 min were obtained from SEVIRI. Additionally, 3D data with 23 vertical layers for each aerosol constituent, size distribution and chemical composition were obtained from the modelling approach and used to compute the AOD at 550 nm by integrating of aerosol extinction coefficient (Qext) over the total atmospheric column. Despite the outbreaks of mineral dust occurring during this period, the overall contribution of organic carbon (OC), black carbon (BC) and sulphate (SO 4 ) compounds to the monthly average AOD values estimated by the model is very important achieving 95% mainly located in the northern part of the studied region. The model outputs and SEVIRI data were validated with AERONET observations presenting correlation coefficients of 0.71 and 0.68 respectively. Three different modes of aerosol were classified based on Ångström coefficient versus AOD and distinguishing between the dominance of fine and coarse aerosol fractions. The analysis implemented reveal that intercomparison of satellite observations with air quality modelling contribute to better understanding of the discrepancies presented in spatial pattern of AOD. • AOD data from satellite observations and air quality modelling were used. • Spatial and temporal variations of the AOD data were investigated. • Better correlation between modelling results and AERONET observations was obtained. • Satellite data and modelling results are in agreement but with different absolute values. • Analysis for observation points and for all domain provided different conclusions.

Brown and black carbons in megacity smogs

AERONET data are used to analyze variations in aerosol radiative characteristics caused by variations in the content of brown and black carbons in smogs of megacities by the example of Beijing, Sao Paulo, Santiago, and Mexico City. It is shown that the contribution of brown carbon to the imaginary part of refractive index at a wavelength of 440 nm in smogs can exceed the contribution of black carbon by a factor of three. In megacity smogs the spectral dependences of the aerosol absorption optical depth can be approximated by power-law functions with satisfactory accuracy, except in certain Beijing smogs at a wavelength of 400 nm for large relative concentrations of brown carbon. It is shown that the contribution of the coarse aerosol fraction to the total aerosol extinction optical depth in megacity smogs can be from 6 to 20% for wavelengths of 440 and 1020 nm, respectively, and that the contribution to aerosol absorption optical depth can be from 22% for a wavelength of 440 nm to 38% for a wavelength of 1020 nm. The aerosol in megacity smogs differs from the smoke aerosol from large-scale fires in the boreal forests of Russia by increased contribution of the coarse aerosol fraction to the total aerosol volume and by a relatively large imaginary part of the refractive index, and, hence, by a larger absorptance.

Transboundary and Local Air Pollutants in Western Japan Distinguished on the Basis of Ratios of Metallic Elements in Size-Segregated Aerosols

Trace metals in aerosols were observed at an urban site (Kumamoto, Kyushu, Japan) and a rural site (Cape Hedo, Okinawa, Japan) to investigate the relative contributions of transboundary air pollutants from mainland Asia and local air pollutants in western Japan. We used a cascade impactor to collect aerosols in five size classes. We apportioned the sources of the air masses on the basis of elemental components. Transboundary and local air pollutants were distinguished by use of the Pb/Cu and V/As ratios in selected size fractions of aerosols. The contribution of Pb (primarily from coal combustion in China) to total anthropogenic elements was greatest in spring, autumn, and winter in the 0.5–1 µm size fraction at both collection sites. The atmospheric environment at both sites was affected by this transboundary air pollutant. The contribution of Cu (primarily from local vehicle traffic) to total anthropogenic elements was greatest in all seasons in the 2.5–10 µm fraction at Kumamoto. Local air pollutants such as road dust, automobile brake abrasion, and waste incineration affected ambient air quality in Kumamoto. Because these pollutants resided mainly in the coarse aerosol fraction (> 2.5 µm), most of them were not transported to Cape Hedo in air bodies that we were able to trace to Kumamoto by backward projection. Based on our data the ambient air quality at Cape Hedo was little affected by local air pollutants emitted in the Kumamoto area.

Retrieval of the particle size distribution function from the data of lidar sensing under the assumption of known refractive index.

This paper presents a method to retrieve the particle size distribution function from the data of vertical lidar sensing. We have used 462 data models obtained at the Zvenigorod AERONET site obtained in 2011-2012. For each laser shot, we considered both fine (with particle sizes in a range from 0.05 to 0.6 μm) and coarse aerosol fractions (from 0.6 to 10 μm), with emphasize on the coarse fraction. Our suggested method is a modification of the Tikhonov method. The Tikhonov method is not optimal for coarse particles because its stabilizer does not and cannot account for the presence of the coarse mode, i.e., existence of more than one maximum of the size distribution function. The components of the matrix Wu-1 located in quadrants II and IV are sensitive to the change of these parameters. Neglecting this fact will lead again to arbitrary estimates of the contribution of the coarse particles even for exact values on the main diagonal and the two diagonals adjacent to it. Our method allows the coarse fraction up to 2.5 μm to be determined unambiguously. For larger particles (>2.5 μm) we recommend using the available sets of the coefficients, but with the level of values to be determined.

Tracing the Sources of Atmospheric Phosphorus Deposition to a Tropical Rain Forest in Panama Using Stable Oxygen Isotopes.

Atmospheric dust deposition can be a significant source of phosphorus (P) in some tropical forests, so information on the origins and solubility of atmospheric P is needed to understand and predict patterns of forest productivity under future climate scenarios. We characterized atmospheric dust P across a seasonal cycle in a tropical lowland rain forest on Barro Colorado Nature Monument (BCNM), Republic of Panama. We traced P sources by combining remote sensing imagery with the first measurements of stable oxygen isotopes in soluble inorganic phosphate (δ(18)OP) in dust. In addition, we measured soluble inorganic and organic P concentrations in fine (<1 μm) and coarse (>1 μm) aerosol fractions and used this data to estimate the contribution of P inputs from dust deposition to the forest P budget. Aerosol dry mass was greater in the dry season (December to April, 5.6-15.7 μg m(-3)) than the wet season (May to November, 3.1-7.1 μg m(-3)). In contrast, soluble P concentrations in the aerosols were lower in the dry season (980-1880 μg P g(-1)) than the wet season (1170-3380 μg P g(-1)). The δ(18)OP of dry-season aerosols resembled that of nearby forest soils (∼19.5‰), suggesting a local origin. In the wet season, when the Trans-Atlantic Saharan dust belt moves north close to Panama, the δ(18)OP of aerosols was considerably lower (∼15.5‰), suggesting a significant contribution of long-distance dust P transport. Using satellite retrieved aerosol optical depth (AOD) and the P concentrations in aerosols we sampled in periods when Saharan dust was evident we estimate that the monthly P input from long distance dust transport during the period with highest Saharan dust deposition is 88 ± 31 g P ha(-1) month(-1), equivalent to between 10 and 29% of the P in monthly litter fall in nearby forests. These findings have important implications for our understanding of modern nutrient budgets and the productivity of tropical forests in the region under future climate scenarios.

Atmospheric particulate mercury at the urban and forest sites in central Poland.

Particulate mercury concentrations were investigated during intensive field campaigns at the urban and forest sites in central Poland, between April 2013 and October 2014. For the first time, quantitative determination of total particulate mercury in coarse (PHg2.2) and fine (PHg0.7) aerosol samples was conducted in Poznań and Jeziory. The concentrations in urban fine and coarse aerosol fractions amounted to <MDL ± 77.1 pg m−3 and <MDL ± 604.9 pg m−3, respectively. Aerosol samples collected during the whole study period showed statistically significant differences for particulate mercury concentrations. A strong impact of meteorological conditions (wind velocity, air mass direction, air temperature, and precipitation amount) on particulate mercury concentrations was also observed. In particular, higher variation and concentration range of PHg0.7 and PHg2.2 was reported for wintertime measurements. An increase in atmospheric particulate mercury during the cold season in the study region indicated that coal combustion, i.e., residential and industrial heating, is the main contribution factor for the selected particle size modes. Coarse particulate Hg at the urban site during summer was mainly attributed to anthropogenic sources, with significant contribution from resuspension processes and long-range transport. The highest values of PHg0.7 and PHg2.2 were found during westerly and southerly wind events, reflecting local emission from highly polluted areas. The period from late fall to spring showed that advection from the southern part of Poland was the main factor responsible for elevated Hg concentrations in fine and coarse particles in the investigated region. Moreover, September 2013 could be given as an example of the influence of additional urban activities which occurred approx. 10 m from the sampling site—construction works connected with replacement of the road surface, asphalting, etc. The concentrations of particulate Hg (>600.0 pg m−3) were much higher than during the following months when any similar situation did not occur. Our investigations confirmed that Hg in urban aerosol samples was predominantly related to local industrial and commercial emissions, whereas the main source of Hg in particulate matter collected at the forest site was connected with regional anthropogenic processes. This paper provides the results of the first long-term measurements of size-fractionated particulate mercury conducted in central Poland, which could be an important insight into atmospheric Hg processes within such a scarcely investigated part of Europe.

Chemical Composition of Fine and Coarse Aerosol Particles in the Central Mediterranean Area during Dust and Non-Dust Conditions

A two-month field campaign was carried out from May to June 2010 at a remote site (Trisaia ENEA Research Centre) in the Southern Italy aiming to identify and quantify the changes of aerosol chemical composition in the presence of Saharan dust. The 24-hr PM_(10) and PM_(2.5) filter samples were analyzed by mass, carbonaceous species, inorganic ions and elemental composition. Saharan dust transport events were identified with two approaches: one recommended by EC (2011) and one based on indicators derived from measurements. Three indicators were used: PM_(2.5)/PM_(10) mass concentrations ratio, Ca/Al ratio and Al concentration. Based on these criteria, four Saharan dust transport events were identified, but only one had elevated dust concentration and leaded to an exceedance of the European short-term (24 hour) limit value of 50 μg/m^3 for PM_(10) (June 16^(th)). The comparison of chemical composition of fine and coarse aerosol fractions during dust and non-dust conditions shows that the presence of dust increases NH_4 and nssSO_4 concentrations in the fine fraction and NO_3 and nssSO_4 concentrations in the coarse fraction. OC and EC concentrations also increase in the fine fraction during dust transport. The uptake of primary and secondary species, inorganic and organic, by dust particles changes their composition and, thus, their properties and this may have implications for human health and climate change.

Properties of agricultural aerosol released during wheat harvest threshing, plowing and sowing

This study shows for the first time a chemical and morphological characterization of agricultural aerosols released during three important agricultural operations: threshing, plowing and sowing. The field campaigns were carried out in the eastern part of the Po Valley, Italy, in summer and autumn 2009. The aerosol particles were sampled on quartz fiber filters and polytetrafluoroethylene membranes in order to allow Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis and Scanning Electron Microscopy equipped with an Energy Dispersive X-ray Spectrometer (SEM-EDS) investigations, respectively. The organic carbon mass concentrations were measured with a Sunset Laboratory Dual-Optical Organic Carbone/Elemental Carbon (OCEC) Aerosol analyzer. The morphological and chemical analyses by SEM-EDS allowed recognizing four main particle classes: organic, silica, calcite and clay minerals. The organic particles contribute to both fine and coarse aerosol fractions up to ca. 50% for all three agricultural activities. This was also confirmed by OCEC analysis for fine fraction. Most of the agricultural aerosols, about 60%, were single particles and the remaining 40% were agglomerations of particles. The ICP-MS results showed that threshing and plowing produce more aerosol particles than sowing, which was characterized by important amounts of clay minerals produced from land soils.

Field measurements of the atmospheric dry deposition fluxes and velocities of polycyclic aromatic hydrocarbons to the global oceans.

The atmospheric dry deposition fluxes of 16 polycyclic aromatic hydrocarbons (PAHs) have been measured, for the first time, in the tropical and subtropical Atlantic, Pacific, and Indian Oceans. Depositional fluxes for fine (0.7-2.7 μm) and coarse (>2.7 μm) aerosol fractions were simultaneously determined with the suspended aerosol phase concentrations, allowing the determination of PAH deposition velocities (vD). PAH dry deposition fluxes (FDD) bound to coarse aerosols were higher than those of fine aerosols for 83% of the measurements. Average FDD for total (fine + coarse) Σ16PAHs (sum of 16 individual PAHs) ranged from 8.33 ng m(-2)d(-1) to 52.38 ng m(-2)d(-1). Mean FDD for coarse aerosol's individual PAHs ranged between 0.13 ng m(-2)d(-1) (Perylene) and 1.96 ng m(-2)d(-1) (Methyl Pyrene), and for the fine aerosol fraction these ranged between 0.06 ng m(-2)d(-1) (Dimethyl Pyrene) and 1.25 ng m(-2)d(-1) (Methyl Chrysene). The estimated deposition velocities went from the highest mean vD for Methyl Chrysene (0.17-13.30 cm s(-1)), followed by Dibenzo(ah)Anthracene (0.29-1.38 cm s(-1)), and other high MW PAHs to minimum values of vD for Dimethyl Pyrene (<0.04 cm s(-1)) and Pyrene (<0.06 cm s(-1)). Dry depositional processes depend on the concentration of PAHs in the suspended aerosol, but also on physicochemical properties and environmental variables (vapor pressure, wind speed, and on the affinity of aerosols for depositing to the sea surface). Empirical parametrizations are proposed to predict the dry depositional velocities of semivolatile organic compounds to the global oceans.

Particulate matter source apportionment in a village situated in industrial region of Central Europe

The bilinear receptor model positive matrix factorization (PMF) was used to apportion particulate matter with an aerodynamic diameter of 1–10 μm (PM1–10) sources in a village, Březno, situated in an industrial region of northern Bohemia in Central Europe. The receptor model analyzed the data sets of 90- and 60-min integrations of PM1–10 mass concentrations and elemental composition for 27 elements. The 14-day sampling campaigns were conducted in the village in summer 2008 and winter 2010. Also, to ensure seasonal and regional representativeness of the data sets recorded in the village, the spatial-temporal variability of the 24-hr PM10 and PM1–10 within 2008–2010 in winter and summer across the multiple sites was evaluated. There were statistically significant interseasonal differences of the 24-hr PM data, but not intrasummer or intrawinter differences of the 24-hr PM1–10 data across the multiple sites. PMF resolved seven sources of PM1–10. They were high-temperature coal combustion; combustion in local heating boilers; marine aerosol; mineral dust; primary biological/wood burning; road dust, car brakes; and gypsum. The main summer factors were assigned to mineral dust (38.2%) and primary biological/wood burning (33.1%). In winter, combustion factors dominated (80%) contribution to PM1–10. The conditional probability function (CPF) helped to identified local sources of PM1–10. The source of marine aerosol from the North Sea and English Channel was indicated by the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT). Implications: This is the first application of PMF to highly time/size resolved PM data in Czech Republic. The coarse aerosol fraction, PM1–10, was chosen with regard to industrial character of the region, sampling site near the coal strip mine and coal power stations. Contrary to expectation, source apportionment did not show dominance of emissions from the coal strip mine. The results will enable local authorities and state bodies responsible for air quality assessment to focus on sources most responsible for air pollution in this industrial region. Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association for (1) details of measurement campaigns; (2) CPF for each of the sources contributing to PM1–10; (3) factors contribution to PM1–10 resolved by PMF; (4) diurnal pattern of road dust, car brake factor in summer and winter; (5) trajectories during the marine aerosol episode in winter 2010; and (6) temporal temperature, concentration, and wind speed relationships during the summer 2008 campaign and winter 2010 campaign.

Method for determining microphysical parameters of atmospheric aerosol from the results of satellite and ground-based multifrequency sounding

A method for reconstructing the parameters of postvolcanic stratospheric aerosol from the results of joint measurements of the aerosol backscattering coefficient with lidar systems based on the Nd:YAG laser and the aerosol extinction coefficient with the SAGE III satellite instrumentation is developed. The most informative set of optical characteristics is determined for each of the microphysical parameters under consideration (concentration, surface area, volume, and effective size of particles of the fine and coarse aerosol fractions). Multiple polynomial regressions between optical and microphysical characteristics of aerosol are obtained. These regressions make it possible to determine the microphysical characteristics of aerosol within a wide range without solving incorrect inverse problems. The results are compared with independent experimental data. The errors of reconstructing microphysical parameters of aerosol are estimated for different situations in the stratosphere. The influence of the shape of particles of the dust fraction on the results of a reconstruction of the microphysical parameters of aerosol is considered.

Nanomaterial inhalation exposure from nanotechnology-based cosmetic powders: a quantitative assessment

In this study we quantified exposures to airborne particles ranging from 14 nm to 20 µm due to the use of nanotechnology-based cosmetic powders. Three nanotechnology-based and three regular cosmetic powders were realistically applied to a mannequin's face while measuring the concentration and size distribution of inhaled aerosol particles. Using these data we calculated that the highest inhaled particle mass was in the coarse aerosol fraction (2.5-10 µm), while particles <100 nm made minimal contribution to the inhaled particle mass. For all powders, 85-93 % of aerosol deposition occurred in the head airways, while <10 % deposited in the alveolar and <5 % in the tracheobronchial regions. Electron microscopy data suggest that nanomaterials were likely distributed as agglomerates across the entire investigated aerosol size range (14 nm-20 µm). Thus, investigation of nanoparticle health effects should consider not only the alveolar region, but also other respiratory system regions where substantial nanomaterial deposition during the actual nanotechnology-based product use would occur.

Two-wavelength lidar characterization of atmospheric aerosol fields at low altitudes over heterogeneous terrain

The possibilities for applying multiwavelength elastic lidar probing of the atmosphere to help monitor air-quality over large industrial and densely populated areas, based predominantly on the use and analysis of commonly obtainable backscatter-related lidar quantities, are examined. Presented are two-wavelength (1064/532 nm ) lidar observations on the spatial distribution, structure, composition, and temporal evolution of close-to-surface atmospheric aerosol fields over heterogeneous orographic areas (adjacent city, plain, and mountain) near Sofia, Bulgaria. Selected winter-time evening lidar measurements are described. Range profiles, histograms, and evolutional range-time diagrams of the aerosol backscatter coefficients, range-corrected lidar signals, normalized standard deviations, and backscatter-related Ångström exponents (BAE) are analyzed. Near-perfect correlation between the aerosol density distribution and orographic differentiation of the underlying terrain is established, finding expression in a sustained horizontal stratification of the probed atmospheric domains. Distinctive features in the spatial distribution and temporal evolution of both the fine- and coarse aerosol fractions are revealed in correlation with terrain's orography. Zonal aerosol particle size distributions are qualitatively characterized by using an approach based on BAE occurrence frequency distribution analysis. Assumptions are made about the aerosol particle type, origin, and dominating size as connected (by transport-modeling data) to local pollution sources.

Analyses of aerosol properties in Hefei based on polarization measurements of a sun photometer

Data collected with a CIMEL CE-318 sun-tracking photometer in Hefei between 2006 and 2008 were collected and inverted using an algorithm which takes polarization information into account. The aerosol optical depths (AOD) showed a pronounced temporal trend, with a maximum value of 0.55 at 440 nm in spring, and values around 0.45 in the remaining seasons. The Ångström parameter for all seasons exceeds 0.80 even in spring. Size distribution showed that both fine and coarse aerosol fractions change significantly and periodically in magnitude and shape during a year. Geometric mean radii for fine and coarse modes are 0.18 μm (standard deviation is 0.016) and 2.7 μm (standard deviation is 0.37), respectively. The spectral dependence of single scattering albedo and reflective index is distinct in the four seasons due to the different aerosol components. All these properties are reported, and it is expected that these aerosol characterizations will help refine aerosol models and clarify the mechanisms of aerosol radiative forcing.

Multiangle implementation of atmospheric correction (MAIAC): 1. Radiative transfer basis and look-up tables

[1] This paper describes a radiative transfer basis of the algorithm MAIAC which performs simultaneous retrievals of atmospheric aerosol and bidirectional surface reflectance from the Moderate Resolution Imaging Spectroradiometer (MODIS). The retrievals are based on an accurate semianalytical solution for the top-of-atmosphere reflectance expressed as an explicit function of three parameters of the Ross–Thick Li–Sparse model of surface bidirectional reflectance. This solution depends on certain functions of atmospheric properties and geometry which are precomputed in the look-up table (LUT). This paper further considers correction of the LUT functions for variations of surface pressure/height and of atmospheric water vapor, which is a common task in the operational remote sensing. It introduces a new analytical method for the water vapor correction of the multiple-scattering path radiance. It also summarizes the few basic principles that provide a high efficiency and accuracy of the LUT-based radiative transfer for the aerosol/surface retrievals and optimize the size of LUT. For example, the single-scattering path radiance is calculated analytically for a given surface pressure and atmospheric water vapor. The same is true for the direct surface-reflected radiance, which along with the single-scattering path radiance largely defines the angular dependence of measurements. For these calculations, the aerosol phase functions and kernels of the surface bidirectional reflectance model are precalculated at a high angular resolution. The other radiative transfer functions depend rather smoothly on angles because of multiple scattering and can be calculated at coarser angular resolution to reduce the LUT size. At the same time, this resolution should be high enough to use the nearest neighbor geometry angles to avoid costly three-dimensional interpolation. The pressure correction is implemented via linear interpolation between two LUTs computed for the standard and reduced pressure levels. A linear mixture and a modified linear mixture methods are used to represent different aerosol types in the aerosol/surface retrievals from several base models of the fine and coarse aerosol fractions. In summary, the developed LUT algorithm allows fast high-accuracy simulations of the outgoing radiance with full variability of the atmospheric and surface bidirectional reflectance properties for the aerosol/surface remote sensing.