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Evaluation of the impact of atmospheric ozone and aerosols on the horizontal global/diffuse UV Index at Livorno (Italy)

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JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS 2016年 146卷 194-204页

作者： Scaglione, Daniele Giulietti, Danilo Morelli, Marco Univ Pisa Dept Phys Pisa Italy Flyby Srl Livorno Italy

A study was conducted at Livorno (Italy) to evaluate the impact of atmospheric aerosols and ozone on the solar UV radiation and its diffuse component at ground in clear sky conditions. Solar UV radiation has been quantified in terms of UV Index (UVI), following the ISO 17166:1999/CIE S007/E-1998 international standard. UVI has been calculated by exploiting the libRadtran radiative transfer modelling software as a function of both the aerosols Optical Depth (AOD) and the Total Ozone Column (TOC). In particular AOD and TOC values have been remotely sensed by the Ozone Monitoring Instrument (OMI) on board the NASA's EOS (Earth Observing System) satellites constellation. An experimental confirmation was also obtained by exploiting global UVI ground-based measurements from the 26/9/14 to 12/8/15 and diffuse UVI ground-based measurements from the 17/5/15 to 12/8/15. For every considered value of Solar Zenith Angle (SZA) and atmospheric condition, estimates and measurements confirm that the diffuse component contributes for more than 50% on the global UV radiation. Therefore an exposure of human skin also to diffuse solar UV radiation can be potentially harmful for health and need to be accurately monitored, e.g. by exploiting innovative applications such as a mobile app with a satellite-based UV dosimeter that has been developed. Global and diffuse UVI variations due to the atmosphere are primarily caused by the TOC variations (typically cyclic): the maximum TOC variation detected by OMI in the area under study leads to a corresponding variation in global and diffuse UVI of about 50%. aerosols in the area concerned, mainly of maritime nature, have instead weaker effects causing a maximum variation of the global and diffuse UVI respectively of 9% and 35% with an SZA of 20 and respectively of 13% and 10% with an SZA of 60 degrees. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： UV index Diffuse UV Ozone aerosols

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Heavy metals and Pb isotopic composition of aerosols in urban and suburban areas of Hong Kong and Guangzhou, South China - Evidence of the long-range transport of air contaminants

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ATMOSPHERIC ENVIRONMENT 2007年第2期41卷 432-447页

作者： Lee, Celine S. L. Li, Xiang-Dong Zhang, Gan Li, Jun Ding, Ai-Jun Wang, Tao Hong Kong Polytech Univ Dept Civil & Struct Engn Kowloon Hong Kong Peoples R China Chinese Acad Sci Guangzhou Inst Geochem State Key Lab Organ Geochem Guangzhou 510640 Peoples R China

Rapid urbanization and industrialization in South China has placed great strain on the environment and on human health. In the present study, the total suspended particulate matter (TSP) in the urban and suburban areas of Hong Kong and Guangzhou, the two largest urban centres in South China, was sampled from December 2003 to January 2005. The samples were analysed for the concentrations of major elements (Al, Fe, Mg and Mn) and trace metals (Cd, Cr, Cu, Pb, V and Zn), and for Pb isotopic composition. Elevated concentrations of metals, especially Cd, Pb, V and Zn, were observed in the urban and suburban areas of Guangzhou, showing significant atmospheric trace element pollution. Distinct seasonal patterns were observed in the heavy metal concentrations of aerosols in Hong Kong, with higher metal concentrations during the winter monsoon period, and lower concentrations during summertime. The seasonal variations in the metal concentrations of the aerosols in Guangzhou were less distinct, suggesting the dominance of local sources of pollution around the city. The Pb isotopic composition in the aerosols of Hong Kong had higher Pb-206/Pb-207 and Pb-208/Pb-207 ratios in winter, showing the influence of Pb from the northern inland areas of China and the Pearl River Delta (PRD) region, and lower Pb-206/Pb-207 and Pb-206/Pb-207 ratios in summer, indicating the influence of Pb from the South Asian region and from marine sources. The back trajectory analysis showed that the enrichment of heavy metals in Hong Kong and Guangzhou was closely associated with the air mass from the north and northeast that originated from northern China, reflecting the long-range transport of heavy metal contaminants from the northern inland areas of China to the South China coast. (c) 2006 Elsevier Ltd. All rights reserved.

关键词： aerosols heavy metals Pb isotopes trajectories South China

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ON THE FILTRATION OF FIBROUS aerosols

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SCIENCE OF THE TOTAL ENVIRONMENT 1986年第3期52卷 189-199页

作者： SPURNY, KR Fraunhofer-Institute for Environmental Chemistry and Ecotoxicology 5948 Schmallenberg-Grafschaft Federal Republic of Germany

Basic processes occurring during the filtration of fibrous aerosols are discussed. Using aerosols containing very fine asbestos fibers, the filtration efficiencies of some analytical ***, Millipore and fiber *** investigated. The collection efficiences were determined by electron microscopy and radiolabeled asbestos fibers and were found to depend upon the pore size of the filter and on the form of the fiber of the respective aerosols. The collection efficiencies were found to lie in the range 40-99.9%. A special problem discussed concerns the orientation of fibrous particles in the vicinity of the entrances to pores in the filter.

关键词： aerosols

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Influence of source distribution and geochemical composition of aerosols on children exposure in the large polymetallic mining region of the Bolivian Altiplano

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SCIENCE OF THE TOTAL ENVIRONMENT 2011年 412卷 170-184页

作者： Goix, Sylvaine Point, David Oliva, Priscia Polve, Mireille Duprey, Jean Louis Mazurek, Hubert Guislain, Ludivine Huayta, Carlos Barbieri, Flavia L. Gardon, Jacques Univ Toulouse IRD CNRS GET F-31400 Toulouse France IRD LCA UMSA La Paz Bolivia Univ Aix Marseille 1 IRD UMR151 Lab Populat Environm Dev F-13331 Marseille 3 France IRD La Paz Bolivia IRD Hydrosci Montpellier France

The Bolivian Altiplano (Highlands) region is subject to intense mining, tailing and smelting activities since centuries because of the presence of large and unique polymetallic ore deposits (Ag, Au, Cu, Pb, Sn, Sb, Zn). A large scale PM10, Pm-2.5 aerosol monitoring survey was conducted during the dry season in one of the largest mining cities of this region (Oruro, 200,000 inhabitants). Aerosol fractions, source distribution and transport were investigated for 23 elements at approximately 1 km(2) scale resolution, and compared to children exposure data obtained within the same geographical space. As, Cd, Pb, Sb, W and Zn in aerosols are present at relatively high concentrations when compared to studies from other mining regions. Arsenic exceeds the European council PM10 guide value (6 ng/m(3)) for 90% of the samples, topping 200 ng/m(3). Ag, As, Cd, Cu, Pb and Sb are present at significantly higher levels in the district located in the vicinity of the smelter zone. At the city level, principal component analysis combined with the mapping of factor scores allowed the identification and deconvolution of four individual sources: i) a natural magmatic source (Co, Cs, Fe, K. Mn, Na, Rb and U) originating from soil dust, resuspended by the traffic activity;ii) a natural sedimentary source (Mg, Ca, Sr, Ba and Th) resulting from the suspension of evaporative salt deposits located South;iii) an anthropogenic source specifically enriched in mined elements (As, Cd, Cu, Pb, Sb and Zn) mainly in the smelting district of the city;and iv) a Ni-Cr source homogenously distributed between the different city districts. Enrichment factors for As, Cd and Sb clearly show the impact of smelting activities, particularly in the finest PM2.5 fraction. Comparison to children's hair metal contents collected in five schools from different districts shows a direct exposure to smelting activity fingerprinted by a unique trace elements pattern (Ag, As, Cu, Pb, Sb). (C) 2011 Elsevier B.V. All right

关键词： aerosols Smelting activities Mining activities Heavy metals Human health Enrichment factors

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Modelling the size-dependent collection efficiency of hedgerows for ambient aerosols

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JOURNAL OF AEROSOL SCIENCE 2006年第8期37卷 990-1015页

作者： Tiwary, Abhishek Morvan, Herve P. Colls, Jeremy J. Univ Nottingham Sch Biosci Nottingham NG7 2RD England Univ Nottingham Sch Civil Engn Nottingham NG7 2RD England

A model for estimating the size-segregated particle collection efficiencies of three hedgerow species of different aerodynamic porosities has been developed and tested in the particle size range 0.5-20 mu m. Collection efficiency (CE) has been described in terms of the coupled effects of the deviation of the approach flow (CEflow) and the filtration through the foliage elements (CEfiltration). Variations in barrier porosities with wind speed, which govern both the flow and the particle collection mechanism, have been modelled using an empirical parameter called the "rigidity factor" (r) for representative leaf-sizes of the three hedge types. Computational fluid dynamics (CFD) allows simulation of velocity fields and turbulence around the barriers, leading to identification of prominent flow separation zones in the wake of denser hedges. Application of different turbulence closure schemes in the CFD model influences the predicted CE only for particles above (5 mu m). Field validations obtained for a porous (hawthorn) and a denser (yew) hedge indicate that CEfiltration ranges between 10 and 35% for "coarse" particles (10-20 mu m) and 1-5% for "fine" particles (0.5-3.5 mu m), the porous hedge showing higher values in the former case and vice versa in the latter. Model predictions of CE over the particle size range studied for the porous hedge lie within 1-30% and for the denser hedge within 0.4-3%. (C) 2005 Elsevier Ltd. All rights reserved.

关键词： hedgerows resistance coefficient collection efficiency aerosols CFD

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Laboratory polarization nephelometer for measurements of optical properties of aerosols

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MEASUREMENT SCIENCE AND TECHNOLOGY 2007年第3期18卷 632-638页

作者： Daugeron, D. Renard, J-B Personne, P. Brun, G. Andre, J-M Univ Blaise Pascal Lab Meteorol Phys Clermont Ferrand France Lab Phys & Chim Environm Orleans France Univ St Etienne Lab Traitement Signal & Instrumentat St Etienne France

Polarization measurements are a powerful tool for better documentation of a variety of liquid and solid particles found in the Earth's atmosphere. Because the solid particles have a non-symmetrical shape, which thereby prevents modelling calculations, it is necessary to build a database of the scattering properties of irregular solid particles in order to interpret the results of remote sensing measurements from aircraft, balloon and satellite. A new laboratory polarization nephelometer was built for this purpose. The particles are levitated by continuous airflow, and are illuminated by a laser at a wavelength of 802 nm. Two avalanche photodiode sensors are used for recording the components of the scattered light perpendicular and parallel to the scattering plane. Detector amplifiers allow light-power detection from a few microwatts down to a few picowatts. Measurements with liquid droplets, made for scattering angles in the 20 degrees-160 degrees range, are in agreement with theoretical calculations, showing that the instrument works well. The first results obtained for irregular solid particles are also presented.

关键词： polarization aerosols dust atmosphere

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Effect of aerosols on Freezing Drops, Hail, and Precipitation in a Midlatitude Storm

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JOURNAL OF THE ATMOSPHERIC SCIENCES 2016年第1期73卷 109-144页

作者： Ilotoviz, Eyal Khain, Alexander P. Benmoshe, Nir Phillips, Vaughan T. J. Ryzhkov, Alexander V. Hebrew Univ Jerusalem Dept Atmospher Sci IL-91904 Jerusalem Israel NOAA Geophys Fluid Dynam Lab Princeton NJ USA Lund Univ Dept Phys Geog & Ecosyst Sci Lund Sweden Univ Oklahoma Cooperat Inst Mesoscale Meteorol Studies Norman OK 73019 USA

A midlatitude hail storm was simulated using a new version of the spectral bin microphysics Hebrew University Cloud Model (HUCM) with a detailed description of time-dependent melting and freezing. In addition to size distributions of drops, plate-, columnar-, and branch-type ice crystals, snow, graupel, and hail, new distributions for freezing drops as well as for liquid water mass within precipitating ice particles were implemented to describe time-dependent freezing and wet growth of hail, graupel, and freezing *** carried out using different aerosol loadings show that an increase in aerosol loading leads to a decrease in the total mass of hail but also to a substantial increase in the maximum size of hailstones. Cumulative rain strongly increases with an increase in aerosol concentration from 100 to about 1000 cm(-3). At higher cloud condensation nuclei (CCN) concentrations, the sensitivity of hailstones' size and surface precipitation to aerosols decreases. The physical mechanism of these effects was analyzed. It was shown that the change in aerosol concentration leads to a change in the major mechanisms of hail formation and growth. The main effect of the increase in the aerosol concentration is the increase in the supercooled cloud water content. Accordingly, at high aerosol concentration, the hail grows largely by accretion of cloud droplets in the course of recycling in the cloud updraft zone. The main mechanism of hail formation in the case of low aerosol concentration is freezing of raindrops.

关键词： Studies Meteorology aerosols Clouds Hail Storms

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Accurate Representations of the Microphysical Processes Occurring during the Transport of Exhaled aerosols and Droplets

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ACS CENTRAL SCIENCE 2021年第1期7卷 200-209页

作者： Walker, Jim S. Archer, Justice Gregson, Florence K. A. Michel, Sarah E. S. Bzdek, Bryan R. Reid, Jonathan P. Univ Bristol Sch Chem Bristol BS8 1TS Avon England

aerosols and droplets from expiratory events play an integral role in transmitting pathogens such as SARS-CoV-2 from an infected individual to a susceptible host. However, there remain significant uncertainties in our understanding of the aerosol droplet microphysics occurring during drying and sedimentation and the effect on the sedimentation outcomes. Here, we apply a new treatment for the microphysical behavior of respiratory fluid droplets to a droplet evaporation/sedimentation model and assess the impact on sedimentation distance, time scale, and particle phase. Above a 100 mu m initial diameter, the sedimentation outcome for a respiratory droplet is insensitive to composition and ambient conditions. Below 100 mu m, and particularly below 80 mu m, the increased settling time allows the exact nature of the evaporation process to play a significant role in influencing the sedimentation outcome. For this size range, an incorrect treatment of the droplet composition, or imprecise use of RH or temperature, can lead to large discrepancies in sedimentation distance (with representative values >1 m, >2 m, and >2 m, respectively). Additionally, a respiratory droplet is likely to undergo a phase change prior to sedimenting if initially <100 mu m in diameter, provided that the RH is below the measured phase change RH. Calculations of the potential exposure versus distance from the infected source show that the volume fraction of the initial respiratory droplet distribution, in this size range, which remains elevated above 1 m decreases from 1 at 1 m to 0.125 at 2 m.

关键词： Anatomy Liquids Sedimentation aerosols Fluids

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Geochemical Behaviour of the Tunisian Background aerosols in Sirocco Wind Circulations

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Advances in Atmospheric Sciences 2009年第3期26卷 390-402页

作者： Chafai AZRI Habib ABIDA Khaled MEDHIOUB Department of Geology Faculty of Sciences of Sfax (FSS)BP 11713000 SfaxTunisia Institute of Preparatory Engineering Studies of Sfax (IPEIS) BP 8053018 SfaxTunisia

This study examines spatial and time evolutions of the principal constituents of the Tunisian background aerosols under Sirocco wind circulations. aerosols coming from the Sahara Desert were found to be loaded with particulate matter, especially silicon. The aerosols were shown to have varying geochemical behaviour along the ＂South-North＂ displacement of the Saharan plumes, depending on the wind flow characteristics, geomorphologic features and the nature of soils swept by the wind. In the south and the center part of the country, the transfer of aerosol constituents to the soil （by gravity and/or impaction） was probably predom- inated by localized enrichment phenomena. The latter are reinforced by the effect of turbulent winds over bare soils, wind wakes and probably selective disintegration, especially in the vicinity of the geomorphologic features of central Tunisia. These relatively high features, extending over important distances, appear to be of paramount importance for the phenomena of redistribution of aerosol constituents even during periods without Sirocco wind circulations. In the northern section of the country, aerosol constituent concentrations dropped to almost 50%, in spite of the abundance of localized turbulent winds. This may be explained by the effect of forests and the relatively dense vegetation cover, which clearly reinforces the transfer phenomena to the soil and the attenuate of dust entrainment.

关键词： aerosols Sahara Sirocco Tunisia turbulent winds

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Bacterial Communities in Marine aerosols Revealed by 454 Pyrosequencing of the 16S rRNA Gene

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JOURNAL OF THE ATMOSPHERIC SCIENCES 2015年第8期72卷 2997-3008页

作者： Xia, Xiaomin Wang, Jianjun Ji, Jiabin Zhang, Jiexia Chen, Liqi Zhang, Rui Hong Kong Univ Sci & Technol Div Environm Sci Kowloon Hong Kong Peoples R China State Ocean Adm Inst Oceanog 3 Key Lab Global Change & Marine Atmospher Chem Xiamen 361005 Fujian Peoples R China Xiamen Univ Inst Marine Microbes & Ecospheres State Key Lab Marine Environm Sci Xiamen Fujian Peoples R China

Although bacteria are an important biological component of aerosol particles, studies of bacterial communities in remote marine aerosol are largely lacking. In this study, aerosol samples were collected over the western Pacific Ocean, the northern Pacific Ocean, the Arctic Ocean, and the Norwegian Sea during the Fifth Chinese National Arctic Research Expedition (CHINARE 5). The diversity and structure of aerosol bacterial communities, based on 454 pyrosequencing, were explored in these samples. The bacterial community in the aerosols collected over the Pacific Ocean was more diverse than over the Norwegian Sea. Both temporal and spatial variations in aerosol bacterial communities were observed based on phylogenetic analysis. These results suggest that the source of air masses shape bacterial communities in aerosol particles over remote marine regions. aerosols are clearly important for long-range transport of bacteria. Since potential human pathogens (e.g., Streptococcus sp.) were retrieved in this study, further investigation is needed to evaluate the potential for their long-distance migration via aerosol.

关键词： Spatial variations Community composition aerosols Genes Atmospheric sciences Pathogens Phylogenetics Expeditions Phylogeny spatial variations Oceans rRNA 16S Migration Air masses Long-range transport Aerosol particles Marine aerosols Arctic Ocean Arctic research Streptococcus Shape Bacteria Air Masses Arctic

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