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Sample records for urban aerosol distribution

  1. Elemental mass size distribution of the Debrecen urban aerosol

    International Nuclear Information System (INIS)

    Kertesz, Zs.; Szoboszlai, Z.; Dobos, E.; Borbely-Kiss, I.

    2007-01-01

    Complete text of publication follows. Size distribution is one of the basic properties of atmospheric aerosol. It is closely related to the origin, chemical composition and age of the aerosol particles, and it influences the optical properties, environmental effects and health impact of aerosol. As part of the ongoing aerosol research in the Group of Ion Beam Applications of the Atomki, elemental mass size distribution of urban aerosol were determined using particle induced X-ray emission (PIXE) analytical technique. Aerosol sampling campaigns were carried out with 9-stage PIXE International cascade impactors, which separates the aerosol into 10 size fractions in the 0.05-30 ?m range. Five 48-hours long samplings were done in the garden of the Atomki, in April and in October, 2007. Both campaigns included weekend and working day samplings. Basically two different kinds of particles could be identified according to the size distribution. In the size distribution of Al, Si, Ca, Fe, Ba, Ti, Mn and Co one dominant peak can be found around the 3 m aerodynamic diameter size range, as it is shown on Figure 1. These are the elements of predominantly natural origin. Elements like S, Cl, K, Zn, Pb and Br appears with high frequency in the 0.25-0.5 mm size range as presented in Figure 2. These elements are originated mainly from anthropogenic sources. However sometimes in the size distribution of these elements a 2 nd , smaller peak appears at the 2-4 μm size ranges, indicating different sources. Differences were found between the size distribution of the spring and autumn samples. In the case of elements of soil origin the size distribution was shifted towards smaller diameters during October, and a 2 nd peak appeared around 0.5 μm. A possible explanation to this phenomenon can be the different meteorological conditions. No differences were found between the weekend and working days in the size distribution, however the concentration values were smaller during the weekend

  2. Retrieval of size distribution for urban aerosols using multispectral optical data

    International Nuclear Information System (INIS)

    Kocifaj, M; Horvath, H

    2005-01-01

    We are dealing with retrieval of aerosol size distribution using multispectral extinction data collected in highly industrialized urban region. Especially, a role of the particle morphology is in the focus of this work. As well known, at present, still many retrieval algorithms are based on simple Lorenz-Mie's theory applicable for perfectly spherical and homogeneous particles, because that approach is fast and can handle the whole size distribution of particles. However, the solid-phase aerosols never render simple geometries, and rather than being spherical or spheroidal they are quite irregular. It is shown, that identification of the modal radius a M of both, the size distribution f(a) and the distribution of geometrical cross section s(a) of aerosol particles is not significantly influenced by the particle's morphology in case the aspect ratio is smaller than 2 and the particles are randomly oriented in the atmospheric environment. On the other hand, the amount of medium-sized particles (radius of which is larger than the modal radius) can be underestimated if distribution of non-spherical grains is substituted by system of volume equivalent spheres. Retrieved volume content of fine aerosols (as characterized by PM 2.5 and PM 1.0 ) can be potentially affected by inappropriate assumption on the particle shape

  3. Aerosol number size distributions over a coastal semi urban location: Seasonal changes and ultrafine particle bursts

    International Nuclear Information System (INIS)

    Babu, S. Suresh; Kompalli, Sobhan Kumar; Moorthy, K. Krishna

    2016-01-01

    Number-size distribution is one of the important microphysical properties of atmospheric aerosols that influence aerosol life cycle, aerosol-radiation interaction as well as aerosol-cloud interactions. Making use of one-yearlong measurements of aerosol particle number-size distributions (PNSD) over a broad size spectrum (~ 15–15,000 nm) from a tropical coastal semi-urban location-Trivandrum (Thiruvananthapuram), the size characteristics, their seasonality and response to mesoscale and synoptic scale meteorology are examined. While the accumulation mode contributed mostly to the annual mean concentration, ultrafine particles (having diameter < 100 nm) contributed as much as 45% to the total concentration, and thus constitute a strong reservoir, that would add to the larger particles through size transformation. The size distributions were, in general, bimodal with well-defined modes in the accumulation and coarse regimes, with mode diameters lying in the range 141 to 167 nm and 1150 to 1760 nm respectively, in different seasons. Despite the contribution of the coarse sized particles to the total number concentration being meager, they contributed significantly to the surface area and volume, especially during transport of marine air mass highlighting the role of synoptic air mass changes. Significant diurnal variation occurred in the number concentrations, geometric mean diameters, which is mostly attributed to the dynamics of the local coastal atmospheric boundary layer and the effect of mesoscale land/sea breeze circulation. Bursts of ultrafine particles (UFP) occurred quite frequently, apparently during periods of land-sea breeze transitions, caused by the strong mixing of precursor-rich urban air mass with the cleaner marine air mass; the resulting turbulence along with boundary layer dynamics aiding the nucleation. These ex-situ particles were observed at the surface due to the transport associated with boundary layer dynamics. The particle growth rates from

  4. Aerosol number size distributions over a coastal semi urban location: Seasonal changes and ultrafine particle bursts

    Energy Technology Data Exchange (ETDEWEB)

    Babu, S. Suresh, E-mail: s_sureshbabu@vssc.gov.in [Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695022 (India); Kompalli, Sobhan Kumar [Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695022 (India); Moorthy, K. Krishna [Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore 560 012 (India)

    2016-09-01

    Number-size distribution is one of the important microphysical properties of atmospheric aerosols that influence aerosol life cycle, aerosol-radiation interaction as well as aerosol-cloud interactions. Making use of one-yearlong measurements of aerosol particle number-size distributions (PNSD) over a broad size spectrum (~ 15–15,000 nm) from a tropical coastal semi-urban location-Trivandrum (Thiruvananthapuram), the size characteristics, their seasonality and response to mesoscale and synoptic scale meteorology are examined. While the accumulation mode contributed mostly to the annual mean concentration, ultrafine particles (having diameter < 100 nm) contributed as much as 45% to the total concentration, and thus constitute a strong reservoir, that would add to the larger particles through size transformation. The size distributions were, in general, bimodal with well-defined modes in the accumulation and coarse regimes, with mode diameters lying in the range 141 to 167 nm and 1150 to 1760 nm respectively, in different seasons. Despite the contribution of the coarse sized particles to the total number concentration being meager, they contributed significantly to the surface area and volume, especially during transport of marine air mass highlighting the role of synoptic air mass changes. Significant diurnal variation occurred in the number concentrations, geometric mean diameters, which is mostly attributed to the dynamics of the local coastal atmospheric boundary layer and the effect of mesoscale land/sea breeze circulation. Bursts of ultrafine particles (UFP) occurred quite frequently, apparently during periods of land-sea breeze transitions, caused by the strong mixing of precursor-rich urban air mass with the cleaner marine air mass; the resulting turbulence along with boundary layer dynamics aiding the nucleation. These ex-situ particles were observed at the surface due to the transport associated with boundary layer dynamics. The particle growth rates from

  5. Preliminary study of elemental mass size distribution of urban aerosol collected in Debrecen

    International Nuclear Information System (INIS)

    Kertesz, Zs.; Borbely-Kiss, I.; Kiss, A.Z.; Koltay, E.; Szabo, Gy.

    2000-01-01

    Complete text of publication follows. Aerosol sampling campaigns were performed during January-February 1998 and August 1998 at an urban location (in the yard of the Institute of Nuclear Research), where aerosol sampling has been carried out continuously since 1991 with single stage Nuclepore filter holders, and since 1994 with 2-stage Gent stacked filter units (SFU). In the winter period in four weekdays 24-hours samplings were performed with a 7-stage PIXE International Cascade Impactor (PCI) and simultaneously with a SFU. On 19-25 August 1998, a week-long aerosol sampling campaign was carried out with the PCI (24-hour samplings), a SFU (24-hour samplings), and a streaker sampler (168-hour continuous sampling). For this period meteorological data were also obtained by a micro-meteorological station installed at the same location by the Radon Group. Elemental concentrations for Al, Si, P, S, Cl, K, Ca, Ti, V, Mn, Fe, Ni, Cu, Zn, Ba and Pb of the aerosol samples were determined by PIXE using the 2 MeV energy proton beam of the 5 MeV Van de Graaff accelerator of the Institute. The obtained average elemental concentrations and the seasonal variation in the elemental concentrations show good correlation with the results obtained from the analysis of the samples collected in previous years. In winter the elemental concentrations are usually lower than in summer, except Cl. The Cl concentration in the coarse fraction is higher with a factor of 10 than in summer due to the salting of the roads and pavements. The summer period included a long weekend with a national holiday. During the weekend the elemental concentrations and also the total mass decreased, and in the beginning of the following week it started to increase. Size distribution: the impactor we have used separate the aerosol within the size range of 0.25 μm and 30 μm into 7 fractions. The mass size distribution for elements of natural origin, like Si, Ca, Ti, Fe, and Mn has one mode: the coarse mode. The

  6. On the Redox Activity of Urban Aerosol Particles: Implications for Size Distribution and Relationships with Organic Aerosol Components

    Directory of Open Access Journals (Sweden)

    Constantini Samara

    2017-10-01

    Full Text Available This article presents the distribution of the dithiothreitol-based (DTT redox activity of water-soluble airborne particulate matter (PM from two urban sites in the city of Thessaloniki, northern Greece in four size ranges (<0.49, 0.49–0.97, 0.97–3.0 and >3 μm. Seasonal and spatial variations are examined. The correlations of the mass-normalized DTT activity with the content of PM in water-soluble organic carbon (WSOC and non-water-soluble carbonaceous species, such as organic and elemental carbon, as well as with solvent-extractable trace organic compounds (polycyclic aromatic hydrocarbons and nitro-derivatives, polychlorinated biphenyls, organochlorines, polybrominated biphenyl ethers and polar organic markers (dicarboxylic acids and levoglucosan, are investigated. Our study provides new and additional insights into the ambient size distribution of the DTT activity of the water-soluble fraction of airborne PM at urban sites and its associations with organic PM components.

  7. Concentrations and size distributions of fine aerosol particles measured at roof level in urban zone

    Science.gov (United States)

    Despiau, S.; Croci, D.

    2007-05-01

    During the experimental Field Experiments to Constrain Models of Atmospheric Pollution and Transport of Emissions (ESCOMPTE) campaign in June-July 2001, concentrations and size distributions of fine particles (14-722 nm) were measured at roof level in downtown Marseille (France). Part of the campaign was dedicated to the study of aerosol behavior in relation to strong photochemical events (which were identified as "IOP" days) and their regional modeling. The analysis of the concentration variations and the evolution of average diurnal size distribution showed that an "IOP day" is not characterized by a specific concentration or its variation, nor by a specific evolution of the average size distribution. The morning traffic rush is detected at roof level by a net increase in particle concentration over the whole size range measured, indicating a production of ultrafine particles by the traffic but also the raising to roof level of particles of the accumulation mode. The increase is observed about 1 hour after the traffic peak at street level, which is characterized by strong increases in NOx and CO concentrations. The corresponding flux of particles at roof level has been estimated around 3 × 104 cm-2 s-1. A specific signature characterized by a strong and rapid burst of concentration (factor 2 to 4 in 15 min) of particles between 25 and 50 nm, independent of the traffic source, has been detected on six occasions during the campaign. These events occur systematically around noon, in cases of strong radiation, low relative humidity, and common wind direction. Despite the high-diameter value of these particles, it is suggested that they could result from a specific "secondary aerosol process" event involving ozone, biogenic, and/or anthropogenic gas precursors like iodine and VOCs.

  8. Studies on aerosol optical properties over urban and semi-urban environments of Hyderabad and Anantapur

    International Nuclear Information System (INIS)

    Lata, K.M.; Badarinath, K.V.S.; Rao, T.V. Ramakrishna; Reddy, R.R.; Ahammed, Y. Nazeer; Gopal, K. Rama; Azeem, P. Abdul

    2003-01-01

    Aerosols in the troposphere exert an important influence on global climate and the environment through scattering, transmission and absorption of radiation as well as acting as nuclei for cloud formation. Atmospheric aerosol particles influence the earth's radiation balance directly by scattering of infrared energy and indirectly by modifying the properties of clouds through microphysical processes. The present study addresses visibility, radiative forcing, size distribution and attenuation of aerosols over the period from January to May, 2001 for urban and semi-urban regions of Hyderabad and Anantapur. High aerosol loading has been observed over urban environment compared to semi-urban environment. Aerosol optical depth values increased from January to April and then decreased during May over both urban and semi-urban regions. Over urban region, visibility decreased from January to April and increased during May. Similar trend has been observed over semi-urban region with relatively higher values of visibility. Radiative forcing estimated using aerosol optical depth values increased from January to April and then decreased during the month of May over urban and semi-urban areas. High visibility and low radiative forcing has been noticed over semi-urban area due to less aerosol loading. Wavelength exponent and turbidity coefficient registered high values over urban environment compared to semi-urban environment. Attenuation coefficient showed high values over urban region compared to semi-urban region. It reveals that semi-urban environment receives high solar flux than urban environment. Using 10 channel quartz crystal microbalance, measurements of total mass concentration and mass size distribution of near surface aerosols has been made over semi-urban environment and compared with size distribution derived from inversion methods based on aerosol optical depth variation with wavelength. The sensitivity of constrained linear inversions for inferring columnar

  9. Size distribution of natural aerosols and radioactive particles issued from radon, in marine and hardly polluted urban atmospheres

    International Nuclear Information System (INIS)

    Tymen, Georges.

    1979-03-01

    With a view to studying the natural radioactive particles produced by atttachment of 222 Rn daughters on environmental aerosol particles, the behaviours of CASELLA MK2 and ANDERSEN cascade impactors were first investigated. Their characteristic stage diameters were determined and size distributions of airborne particles were obtained in various situations. Moreover, an experimental and automatic equipment for measuring radon was devised and a method was developed in order to evaluate RaA, RaB, RaC concentrations in the free atmosphere. A degree of radioactive desequilibrium between 222 Rn and its daughters, more important than that in other locations was thus demonstrated. Furthermore, by means of various aerosol collection systems (ion tubes, diffusion batteries, cascade impactors, filters), the cumulative size distribution of natural radioactivity was established in the air, at ground level. Finally, from a theory of attachment of small radioactive ions on atmospheric particles, a tentative explanation of experimental results was made [fr

  10. PIXE technique use for urban aerosol characterization

    International Nuclear Information System (INIS)

    Dias da Cunha, K.; Lazarra, M.; Nazare, R.A.; D'Oliveira, D.; Barros Leite, C.V.

    1996-01-01

    A cascade impactor and PIXE technique were used to estimate the air pollution in a urban area. PIXE is a multielementar method and for all elements the detection limit is about nanograms. The particle size distribution was determined using a cascade impactor with six stage. It collects the particles in the respirable and invaluable of aerosol. The samples were collected close to Planetary in Rio de Janeiro City. The results indicate that particles containing Cu, Zn, Ni, Fe, Mn, Cr, V, Ti, Ca and K. The particle was in the respirable fraction of with MMAD,2 μm. (author)

  11. Aerosol Size Distributions In Auckland.

    Czech Academy of Sciences Publication Activity Database

    Coulson, G.; Olivares, G.; Talbot, Nicholas

    2016-01-01

    Roč. 50, č. 1 (2016), s. 23-28 E-ISSN 1836-5876 Institutional support: RVO:67985858 Keywords : aerosol size distribution * particle number concentration * roadside Subject RIV: CF - Physical ; Theoretical Chemistry

  12. Can Aerosol Offset Urban Heat Island Effect?

    Science.gov (United States)

    Jin, M. S.; Shepherd, J. M.

    2009-12-01

    The Urban Heat Island effect (UHI) refers to urban skin or air temperature exceeding the temperatures in surrounding non-urban regions. In a warming climate, the UHI may intensify extreme heat waves and consequently cause significant health and energy problems. Aerosols reduce surface insolation via the direct effect, namely, scattering and absorbing sunlight in the atmosphere. Combining the National Aeronautics and Space Administration (NASA) AERONET (AErosol RObotic NETwork) observations over large cities together with Weather Research and Forecasting Model (WRF) simulations, we find that the aerosol direct reduction of surface insolation range from 40-100 Wm-2, depending on seasonality and aerosol loads. As a result, surface skin temperature can be reduced by 1-2C while 2-m surface air temperature by 0.5-1C. This study suggests that the aerosol direct effect is a competing mechanism for the urban heat island effect (UHI). More importantly, both aerosol and urban land cover effects must be adequately represented in meteorological and climate modeling systems in order to properly characterize urban surface energy budgets and UHI.

  13. Aerosol particle mixing state, refractory particle number size distributions and emission factors in a polluted urban environment: Case study of Metro Manila, Philippines

    Science.gov (United States)

    Kecorius, Simonas; Madueño, Leizel; Vallar, Edgar; Alas, Honey; Betito, Grace; Birmili, Wolfram; Cambaliza, Maria Obiminda; Catipay, Grethyl; Gonzaga-Cayetano, Mylene; Galvez, Maria Cecilia; Lorenzo, Genie; Müller, Thomas; Simpas, James B.; Tamayo, Everlyn Gayle; Wiedensohler, Alfred

    2017-12-01

    Ultrafine soot particles (black carbon, BC) in urban environments are related to adverse respiratory and cardiovascular effects, increased cases of asthma and premature deaths. These problems are especially pronounced in developing megacities in South-East Asia, Latin America, and Africa, where unsustainable urbanization ant outdated environmental protection legislation resulted in severe degradation of urban air quality in terms of black carbon emission. Since ultrafine soot particles do often not lead to enhanced PM10 and PM2.5 mass concentration, the risks related to ultrafine particle pollution may therefore be significantly underestimated compared to the contribution of secondary aerosol constituents. To increase the awareness of the potential toxicological relevant problems of ultrafine black carbon particles, we conducted a case study in Metro Manila, the capital of the Philippines. Here, we present a part of the results from a detailed field campaign, called Manila Aerosol Characterization Experiment (MACE, 2015). Measurements took place from May to June 2015 with the focus on the state of mixing of aerosol particles. The results were alarming, showing the abundance of externally mixed refractory particles (soot proxy) at street site with a maximum daily number concentration of approximately 15000 #/cm3. That is up to 10 times higher than in cities of Western countries. We also found that the soot particle mass contributed from 55 to 75% of total street site PM2.5. The retrieved refractory particle number size distribution appeared to be a superposition of 2 ultrafine modes at 20 and 80 nm with a corresponding contribution to the total refractory particle number of 45 and 55%, respectively. The particles in the 20 nm mode were most likely ash from metallic additives in lubricating oil, tiny carbonaceous particles and/or nucleated and oxidized organic polymers, while bigger ones (80 nm) were soot agglomerates. To the best of the authors' knowledge, no other

  14. Seasonal dependence of aerosol processing in urban Philadelphia

    Science.gov (United States)

    Avery, A. M.; Waring, M. S.; DeCarlo, P. F.

    2017-12-01

    Urban aerosols pose an important threat to human health due to the conflation of emissions and concentrated population exposed. Winter and summer aerosol and trace gas measurements were taken in downtown Philadelphia in 2016. Measurements included aerosol composition and size with an Aerodyne Aerosol Mass Spectrometer (AMS), particle size distributions with an SMPS, and an aethalometer. Trace gas measurements of O3, NO, CH4, CO, and CO2 were taken concurrently. Sampling in seasonal extremes provided contrast in aerosol and trace gas composition, aerosol processing, and emission factors. Inorganic aerosol components contributed approximately 60% of the submicron aerosol mass, while summertime aerosol composition was roughly 70% organic matter. Positive Matrix Factorization (PMF) on the organic aerosol (OA) matrix revealed three factors in common in each season, including an oxygenated organic aerosol (OOA) factor with different temporal behavior in each season. In summertime, OOA varied diurnally with ozone and daytime temperature, but in the wintertime, it was anti-correlated with ozone and temperature, and instead trended with calculated liquid water, indicating a seasonally-dependent processing of organic aerosol in Philadelphia's urban environment. Due to the inorganic dominant winter aerosol, liquid water much higher (2.65 μg/m3) in winter than in summer (1.54 μg/m3). Diurnally varying concentrations of background gas phase species (CH4, CO2) were higher in winter and varied less as a result of boundary layer conditions; ozone was also higher in background in winter than summer. Winter stagnation events with low windspeed showed large buildup of trace gases CH4, CO, CO2, and NO. Traffic related aerosol was also elevated with black carbon and hydrocarbon-like OA (HOA) plumes of each at 3-5 times higher than the winter the average value for each. Winter ratios of HOA to black carbon were significantly higher in the winter than the summer due to lower

  15. Diurnal cycling of urban aerosols under different weather regimes

    Science.gov (United States)

    Gregorič, Asta; Drinovec, Luka; Močnik, Griša; Remškar, Maja; Vaupotič, Janja; Stanič, Samo

    2016-04-01

    A one month measurement campaign was performed in summer 2014 in Ljubljana, the capital of Slovenia (population 280,000), aiming to study temporal and spatial distribution of urban aerosols and the mixing state of primary and secondary aerosols. Two background locations were chosen for this purpose, the first one in the city center (urban background - KIS) and the second one in the suburban background (Brezovica). Simultaneous measurements of black carbon (BC) and particle number size distribution of submicron aerosols (PM1) were conducted at both locations. In the summer season emission from traffic related sources is expected to be the main local contribution to BC concentration. Concentrations of aerosol species and gaseous pollutants within the planetary boundary layer are controlled by the balance between emission sources of primary aerosols and gases, production of secondary aerosols, chemical reactions of precursor gases under solar radiation and the rate of dilution by mixing within the planetary boundary layer (PBL) as well as with tropospheric air. Only local emission sources contribute to BC concentration during the stable PBL with low mixing layer height, whereas during the time of fully mixed PBL, regionally transported BC and other aerosols can contribute to the surface measurements. The study describes the diurnal behaviour of the submicron aerosol at the urban and suburban background location under different weather regimes. Particles in three size modes - nucleation (humidity, wind speed and direction), diurnal profile differs for sunny, cloudy and rainy days. Nucleation mode particles were found to be subjected to lower daily variation and only slightly influenced by weather, as opposed to Aitken and accumulation mode particles. The highest correlation between BC and particle number concentration is observed during stable atmospheric conditions in the night and morning hours and is attributed to different particle size modes, depending on the

  16. Onshore Wind Speed Modulates Microbial Aerosols along an Urban Waterfront

    Directory of Open Access Journals (Sweden)

    M. Elias Dueker

    2017-11-01

    Full Text Available Wind blowing over aquatic and terrestrial surfaces produces aerosols, which include microbial aerosols. We studied the effect of onshore wind speeds on aerosol concentrations as well as total and culturable microbial aerosols (bacterial and viral at an urban waterfront (New York, NY, United States of America. We used two distinct methods to characterize microbial aerosol responses to wind speed: A culture-based exposure-plate method measuring viable bacterial deposition near-shore (CFU accumulation rate; and a culture-independent aerosol sampler-based method measuring total bacterial and viral aerosols (cells m−3 air. While ambient coarse (>2 µm and fine (0.3–2 µm aerosol particle number concentrations (regulated indicators of air quality decreased with increasing onshore wind speeds, total and depositing culturable bacterial aerosols and total viral aerosols increased. Taxonomic identification of the 16S rDNA of bacterial aerosol isolates suggested both terrestrial and aquatic sources. Wind appears to increase microbial aerosol number concentrations in the near-shore environment by onshore transport at low wind speeds (<4 m s−1, and increased local production and transport of new microbial aerosols from adjacent water surfaces at higher wind speeds (>4 m s−1. This study demonstrates a wind-modulated microbial connection between water and air in the coastal urban environment, with implications for public health management and urban microbial ecology.

  17. Hourly variation of elemental components of urban aerosol in Debrecen

    International Nuclear Information System (INIS)

    Kertesz, Zs.; Dobos, E.; Szoboszlai, Z.; Borbely-Kiss, I.

    2007-01-01

    Complete text of publication follows. With the use of accelerator based PIXE elemental analysis technique and statistical methods, systematic investigation of aerosol samples have been performed in the Institute of Nuclear Research of the Hungarian Academy of Sciences for 20 years determining the elemental composition, size distribution, seasonal and long term time variation, sources and lung deposition probabilities of atmospheric aerosol characteristic to the east-Hungary region. In continuation of this research we observed the short-term time variation of the elemental components in spring and in autumn 2007, at the end and the beginning of the heating season. We studied the changes in the elemental concentrations, their periodicity, correlation with other elements and meteorological parameters. The sampling was done with a PIXE International streaker sampler, which enables a time-discrete record of fine (PM2.5) and coarse (PM10-2.5) size fractions. Sampling campaigns were carried out in the garden of the Atomki on 10-16 April and 10-19 October. Elemental concentration data (Z > 12) with 2h time resolution were determined on the two size fractions. Statistical evaluation and source determination were carried out with the positive mass factorization method developed for aerosol source characterization by US EPA. Six sources of the urban aerosols were identified: 2 types of soil - loess and sand - biomass burning, sulfate originating form long range transport processes, an unknown source enriched with chlorine and heavy metals originating form traffic. The hourly contribution of some sources for the week 12-19 October is presented on figure 1. In the time trend of soil and heavy metals a periodicity can be observed: the peaks in the morning and in the evening of working days fall together with traffic rush hours. Peaks of biomass burning appear during nights and mornings indicating its origin of domestic heating. Several emission episodes were also detected. Such

  18. Carbonaceous aerosols in Norwegian urban areas

    Directory of Open Access Journals (Sweden)

    K. E. Yttri

    2009-03-01

    Full Text Available Little is known regarding levels and source strength of carbonaceous aerosols in Scandinavia. In the present study, ambient aerosol (PM10 and PM2.5 concentrations of elemental carbon (EC, organic carbon (OC, water-insoluble organic carbon (WINSOC, and water-soluble organic carbon (WSOC are reported for a curbside site, an urban background site, and a suburban site in Norway in order to investigate their spatial and seasonal variations. Aerosol filter samples were collected using tandem filter sampling to correct for the positive sampling artefact introduced by volatile and semivolatile OC. Analyses were performed using the thermal optical transmission (TOT instrument from Sunset Lab Inc., which corrects for charring during analysis. Finally, we estimated the relative contribution of OC from wood burning based on the samples content of levoglucosan.

    Levels of EC varied by more than one order of magnitude between sites, likely due to the higher impact of vehicular traffic at the curbside and the urban background sites. In winter, the level of particulate organic carbon (OCp at the suburban site was equal to (for PM10 or even higher (for PM2.5 than the levels observed at the curbside and the urban background sites. This finding was attributed to the impact of residential wood burning at the suburban site in winter, which was confirmed by a high mean concentration of levoglucosan (407 ng m−3. This finding indicates that exposure to primary combustion derived OCp could be equally high in residential areas as in a city center. It is demonstrated that OCp from wood burning (OCwood accounted for almost all OCp at the suburban site in winter, allowing a new estimate of the ratio TCp/levoglucosan for both PM10 and PM2.5. Particulate carbonaceous material (PCM

  19. Characterization of urban aerosol in Cork city (Ireland) using aerosol mass spectrometry

    Science.gov (United States)

    Dall'Osto, M.; Ovadnevaite, J.; Ceburnis, D.; Martin, D.; Healy, R. M.; O'Connor, I. P.; Kourtchev, I.; Sodeau, J. R.; Wenger, J. C.; O'Dowd, C.

    2013-05-01

    Ambient wintertime background urban aerosol in Cork city, Ireland, was characterized using aerosol mass spectrometry. During the three-week measurement study in 2009, 93% of the ca. 1 350 000 single particles characterized by an Aerosol Time-of-Flight Mass Spectrometer (TSI ATOFMS) were classified into five organic-rich particle types, internally mixed to different proportions with elemental carbon (EC), sulphate and nitrate, while the remaining 7% was predominantly inorganic in nature. Non-refractory PM1 aerosol was characterized using a High Resolution Time-of-Flight Aerosol Mass Spectrometer (Aerodyne HR-ToF-AMS) and was also found to comprise organic aerosol as the most abundant species (62%), followed by nitrate (15%), sulphate (9%) and ammonium (9%), and chloride (5%). Positive matrix factorization (PMF) was applied to the HR-ToF-AMS organic matrix, and a five-factor solution was found to describe the variance in the data well. Specifically, "hydrocarbon-like" organic aerosol (HOA) comprised 20% of the mass, "low-volatility" oxygenated organic aerosol (LV-OOA) comprised 18%, "biomass burning" organic aerosol (BBOA) comprised 23%, non-wood solid-fuel combustion "peat and coal" organic aerosol (PCOA) comprised 21%, and finally a species type characterized by primary {m/z} peaks at 41 and 55, similar to previously reported "cooking" organic aerosol (COA), but possessing different diurnal variations to what would be expected for cooking activities, contributed 18%. Correlations between the different particle types obtained by the two aerosol mass spectrometers are also discussed. Despite wood, coal and peat being minor fuel types used for domestic space heating in urban areas, their relatively low combustion efficiencies result in a significant contribution to PM1 aerosol mass (44% and 28% of the total organic aerosol mass and non-refractory total PM1, respectively).

  20. Characterization of urban aerosol in Cork city (Ireland using aerosol mass spectrometry

    Directory of Open Access Journals (Sweden)

    M. Dall'Osto

    2013-05-01

    Full Text Available Ambient wintertime background urban aerosol in Cork city, Ireland, was characterized using aerosol mass spectrometry. During the three-week measurement study in 2009, 93% of the ca. 1 350 000 single particles characterized by an Aerosol Time-of-Flight Mass Spectrometer (TSI ATOFMS were classified into five organic-rich particle types, internally mixed to different proportions with elemental carbon (EC, sulphate and nitrate, while the remaining 7% was predominantly inorganic in nature. Non-refractory PM1 aerosol was characterized using a High Resolution Time-of-Flight Aerosol Mass Spectrometer (Aerodyne HR-ToF-AMS and was also found to comprise organic aerosol as the most abundant species (62%, followed by nitrate (15%, sulphate (9% and ammonium (9%, and chloride (5%. Positive matrix factorization (PMF was applied to the HR-ToF-AMS organic matrix, and a five-factor solution was found to describe the variance in the data well. Specifically, "hydrocarbon-like" organic aerosol (HOA comprised 20% of the mass, "low-volatility" oxygenated organic aerosol (LV-OOA comprised 18%, "biomass burning" organic aerosol (BBOA comprised 23%, non-wood solid-fuel combustion "peat and coal" organic aerosol (PCOA comprised 21%, and finally a species type characterized by primary extit{m/z}~peaks at 41 and 55, similar to previously reported "cooking" organic aerosol (COA, but possessing different diurnal variations to what would be expected for cooking activities, contributed 18%. Correlations between the different particle types obtained by the two aerosol mass spectrometers are also discussed. Despite wood, coal and peat being minor fuel types used for domestic space heating in urban areas, their relatively low combustion efficiencies result in a significant contribution to PM1 aerosol mass (44% and 28% of the total organic aerosol mass and non-refractory total PM1, respectively.

  1. Seasonal variation of the particle size distribution of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in urban aerosol of Guangzhou, China.

    Science.gov (United States)

    Tang, X L; Bi, X H; Sheng, G Y; Tan, J H; Fu, J M

    2006-06-01

    Seasonal aerosol samples have been collected by Andersen Hi-Vol pumping system equipped with a five stage cascade impactor and a backup filter (size range: 10-7.2 microm, 7.2-3.0 microm, 3.0-1.5 microm, 1.5-0.95 microm, 0.95-0.49 microm, gas chromatography and PAHs were measured using gas chromatography/mass spectrometry analysis. The bimodal log-normal distributions of n-alkanes and semi-volatile PAHs were found, while for non-volatile PAHs that was unimodal, so much as the mode of semi-volatile PAHs was similar with that of the particles. The n-alkanes and PAHs were preferably associated with fine particles. C (max) (carbon number maximum) (C(22)-C(26)), CPI (carbon preference index) (1.12-1.21), U/R (unresolved to resolved components ratio) (7.42-10.7), wax% (0.9-3.12%) and the diagnostic ratios for PAHs revealed that vehicular emission was the major source of these organic compounds during the study periods, while the contribution of epicuticular waxes emitted by terrestrial plants was minor. CPI(2) (values for petrogenic hydrocarbons), CPI(3) (values for biogenic n-alkanes) and wax% revealed that the natural preferentially accumulated in the larger aerosol while the anthropogenic in the smaller. In addition, the different MMDs (mass median diameters) for n-alkanes and PAHs were observed in different seasons. The MMDs for n-alkanes and PAHs were higher in autumn/winter than those in spring/summer. The seasonal effect was related to the hydrocarbon content in the individual particulate fractions, showing a preferential association of n-alkanes and PAHs with larger particles in the autumn/winter season.

  2. Impact of Gobi desert dust on aerosol chemistry of Xi'an, inland China during spring 2009: differences in composition and size distribution between the urban ground surface and the mountain atmosphere

    Directory of Open Access Journals (Sweden)

    G. H. Wang

    2013-01-01

    Full Text Available Composition and size distribution of atmospheric aerosols from Xi'an city (~400 m, altitude in inland China during the spring of 2009 including a massive dust event on 24 April were measured and compared with a parallel measurement at the summit (2060 m, altitude of Mt. Hua, an alpine site nearby Xi'an. EC (elemental carbon, OC (organic carbon and major ions in the city were 2–22 times higher than those on the mountaintop during the whole sampling period. Compared to that in the non-dust period a sharp increase in OC was observed at both sites during the dust period, which was mainly caused by an input of biogenic organics from the Gobi desert. However, adsorption/heterogeneous reaction of gaseous organics with dust was another important source of OC in the urban, contributing 22% of OC in the dust event. In contrast to the mountain atmosphere where fine particles were less acidic when dust was present, the urban fine particles became more acidic in the dust event than in the non-dust event, mainly due to enhanced heterogeneous formation of nitrate and diluted NH3. Cl and NO3 in the urban air during the dust event significantly shifted toward coarse particles. Such redistributions were further pronounced on the mountaintop when dust was present, resulting in both ions almost entirely staying in coarse particles. On the contrary, no significant spatial difference in size distribution of SO42− was found between the urban ground surface and the mountain atmosphere, which dominated in the fine mode (<2.1 μm during the nonevent and comparably distributed in the fine (<2.1 μm and coarse (>2.1 μm modes during the dust event.

  3. A contribution to the study of atmospheric aerosols in urban, marine and oceanic areas

    International Nuclear Information System (INIS)

    Butor, Jean-Francois

    1980-01-01

    A study of atmospheric aerosols, especially marine aerosols, was carried out, using impactors and nuclepore filters in association with electron microscopy techniques. The performances of the experimental device were first determined carefully and a generator of monodisperse aerosols was built at the laboratory in order to measure the efficiency of the filters used. It was demonstrated that the chief atmospheric particulate constituents could be determined by electron microscopy. The particle-size distribution of oceanic aerosols was next studied on the basis of the results of three measurement campaigns carried out in the Atlantic ocean. In Brest, where urban aerosols more or less affected by the meteorological conditions can be found superimposed to marine aerosols, an assessment was made of the effects of moderate anthropogeneous pollution on marine aerosols as measured in the Atlantic ocean. Two cases of marine aerosol disturbance, the former by an accidental marine pollution, the latter linked to a natural local phenomenon are related and a model of the marine aerosol in the Northern Atlantic ocean is proposed which takes into account the mean particle size spectra, the characteristic parameters of its three-modal distribution and the qualitative analysis of particles. (author) [fr

  4. Characterization of urban aerosol sources in Debrecen, Hungary

    International Nuclear Information System (INIS)

    Kertesz, Zs.; Szoboszlai, T.; Angyal, A.; Dobos, E.; Borbely-Kiss, I.

    2009-01-01

    Complete text of publication follows. Aerosol pollution represents significant health hazard in urban environments. Despite the fact that Debrecen has not a much stressed environment the city is highly exposed to aerosol pollution. In order to evaluate the impact of aerosol particles on health, the knowledge of the particle size distribution, chemical composition, sources, and their change in time and space is needed. This work presents a source apportionment study of fine (particles with aerodynamic diameter less than 2.5 μm) and coarse (particles with aerodynamic diameter between 2.5 and 10 μm) particulate matter in Debrecen by following the evolution of the elemental components with hourly time resolution. The variation of the elemental concentrations, their periodicity, correlation with other elements and meteorological parameters were studied on samples collected in different seasons. Aerosol sources were determined using the positive matrix factorization (PMF) method. Aerosol samples were collected in the garden of the ATOMKI with a 2-stage sequential streaker sampler manufactured by PIXE International, which collected the fine and coarse fraction separately with few hours' time resolution. Between October 2007 and January 2009 five 10-days long sampling campaigns were carried out. The elemental composition was determined by Particle Induced X-ray emission (PIXE) for Z ≥ 13, and the elemental carbon (BC) content was estimated with a smoke stain reflectometer. Source apportionment was carried out with the PMF receptor model developed for aerosol source characterization, provided by US EPA. Mass of species apportioned to factor, percentage of species apportioned to factors and average factor contributions of the campaigns, of working days and weekends and within the days were calculated. The PMF analysis resulted seven factors in the fine and seven factors in the coarse mode. The main sources of atmospheric aerosol in the city of Debrecen were traffic

  5. Aerosol distribution measurements by laser - Doppler - spectroscopy

    International Nuclear Information System (INIS)

    Baldassari, J.

    1977-01-01

    Laser-Doppler-Spectroscopy is used to study particle size distribution, especially sodium aerosols, in the presence of uncondensable gases. Theoretical basis are given, and an experimental technique is described. First theoretical results show reasonably good agreement with experimental data available; this method seems to be a promising one. (author)

  6. Modelling and measurements of urban aerosol processes on the neighborhood scale in Rotterdam, Oslo and Helsinki

    Science.gov (United States)

    Karl, M.; Kukkonen, J.; Keuken, M. P.; Lützenkirchen, S.; Pirjola, L.; Hussein, T.

    2015-12-01

    This study evaluates the influence of aerosol processes on the particle number (PN) concentrations in three major European cities on the temporal scale of one hour, i.e. on the neighborhood and city scales. We have used selected measured data of particle size distributions from previous campaigns in the cities of Helsinki, Oslo and Rotterdam. The aerosol transformation processes were evaluated using an aerosol dynamics model MAFOR, combined with a simplified treatment of roadside and urban atmospheric dispersion. We have compared the model predictions of particle number size distributions with the measured data, and conducted sensitivity analyses regarding the influence of various model input variables. We also present a simplified parameterization for aerosol processes, which is based on the more complex aerosol process computations; this simple model can easily be implemented to both Gaussian and Eulerian urban dispersion models. Aerosol processes considered in this study were (i) the coagulation of particles, (ii) the condensation and evaporation of n-alkanes, and (iii) dry deposition. The chemical transformation of gas-phase compounds was not taken into account. It was not necessary to model the nucleation of gas-phase vapors, as the computations were started with roadside conditions. Dry deposition and coagulation of particles were identified to be the most important aerosol dynamic processes that control the evolution and removal of particles. The effect of condensation and evaporation of organic vapors emitted by vehicles on particle numbers and on particle size distributions was examined. Under inefficient dispersion conditions, condensational growth contributed significantly to the evolution of PN from roadside to the neighborhood scale. The simplified parameterization of aerosol processes can predict particle number concentrations between roadside and the urban background with an inaccuracy of ∼ 10 %, compared to the fully size-resolved MAFOR model.

  7. Size-segregated concentration of heavy metals in an urban aerosol of the Balkans region (Belgrade

    Directory of Open Access Journals (Sweden)

    Đorđević D.

    2013-04-01

    Full Text Available This work focuses on the heavy metals contents of the size-segregated urban aerosol of the continental area of Balkans. The distribution of nano/micron heavy metals in the size-segregated urban aerosol of Belgrade center was studied during the summer–autumn of 2008. The particle size distribution in the size ranges Dp ≤ 0.49 μm, 0.49 ≤ Dp ≤ 0.95 μm, 0.95 ≤ Dp ≤ 1.5 μm, 1.5 ≤ Dp ≤ 3.0 μm, 3.0 ≤ Dp ≤ 7.2 μm and Dp ≥ 7.2 μm was measured. The aerosol samples were submitted to gravimetric and chemical analyses. The obtained mean mass concentration of the PM fractions was in accordance with an urban aerosol distribution. The aerosol mass concentrations were determined by gravimetric measurements (mGM and, for heavy metals analyzed by ICP/MS.

  8. Aerosol composition of urban plumes passing over a rural monitoring site

    International Nuclear Information System (INIS)

    Ellestad, T.G.

    1980-01-01

    A field study conducted at a ground site 100 km north of St. Louis, Mo., to measure the aerosol composition and gaseous concentrations of urban plumes passing the site is discussed. Coarse and fine aerosol elemental concentrations, height scattering, meteorological data and concentrations of SO 2 , CO, O 3 , and NO-NO/sub x/ were measured and then analyzed together with data from associate investigators on fluorocarbon-11, total hydrocarbons, and size distributions. The results show that: (1) gaseous and elemental aerosol concentrations at the ground site 100 km from the St. Louis urban area were clearly influenced by the St. Louis urban plume, (2) the urban plumes of Chicago and Indianapolis, 350 km from the ground site, may have been detected, (3) sulfur compounds, presumably sulfates, accounted for 30-40% of the mass loading within the St. Louis urban plume, and resided almost entirely within the size range below 2.5 microns, (4) the most reliable urban-plume tracers in this study were fine Pb, fluorocarbon-11, total nonmethane hydrocarbons, and CO, and (5) over a period of several days, there may have been a regional buildup of fine S, light scattering, aerosol mass, O 3 , and NO/sub x/ and, to a lesser extent, CO and fluorocarbon-11

  9. Characterization of urban aerosol using aerosol mass spectrometry and proton nuclear magnetic resonance spectroscopy

    Science.gov (United States)

    Cleveland, M. J.; Ziemba, L. D.; Griffin, R. J.; Dibb, J. E.; Anderson, C. H.; Lefer, B.; Rappenglück, B.

    2012-07-01

    Particulate matter was measured during August and September of 2006 in Houston as part of the Texas Air Quality Study II Radical and Aerosol Measurement Project. Aerosol size and composition were determined using an Aerodyne quadrupole aerosol mass spectrometer. Aerosol was dominated by sulfate (4.1 ± 2.6 μg m-3) and organic material (5.5 ± 4.0 μg m-3), with contributions of organic material from both primary (˜32%) and secondary (˜68%) sources. Secondary organic aerosol appears to be formed locally. In addition, 29 aerosol filter samples were analyzed using proton nuclear magnetic resonance (1H NMR) spectroscopy to determine relative concentrations of organic functional groups. Houston aerosols are less oxidized than those observed elsewhere, with smaller relative contributions of carbon-oxygen double bonds. These particles do not fit 1H NMR source apportionment fingerprints for identification of secondary, marine, and biomass burning organic aerosol, suggesting that a new fingerprint for highly urbanized and industrially influenced locations be established.

  10. Wintertime hygroscopicity and volatility of ambient urban aerosol particles

    Science.gov (United States)

    Enroth, Joonas; Mikkilä, Jyri; Németh, Zoltán; Kulmala, Markku; Salma, Imre

    2018-04-01

    Hygroscopic and volatile properties of atmospheric aerosol particles with dry diameters of (20), 50, 75, 110 and 145 nm were determined in situ by using a volatility-hygroscopicity tandem differential mobility analyser (VH-TDMA) system with a relative humidity of 90 % and denuding temperature of 270 °C in central Budapest during 2 months in winter 2014-2015. The probability density function of the hygroscopic growth factor (HGF) showed a distinct bimodal distribution. One of the modes was characterised by an overall mean HGF of approximately 1.07 (this corresponds to a hygroscopicity parameter κ of 0.033) independently of the particle size and was assigned to nearly hydrophobic (NH) particles. Its mean particle number fraction was large, and it decreased monotonically from 69 to 41 % with particle diameter. The other mode showed a mean HGF increasing slightly from 1.31 to 1.38 (κ values from 0.186 to 0.196) with particle diameter, and it was attributed to less hygroscopic (LH) particles. The mode with more hygroscopic particles was not identified. The probability density function of the volatility GF (VGF) also exhibited a distinct bimodal distribution with an overall mean VGF of approximately 0.96 independently of the particle size, and with another mean VGF increasing from 0.49 to 0.55 with particle diameter. The two modes were associated with less volatile (LV) and volatile (V) particles. The mean particle number fraction for the LV mode decreased from 34 to 21 % with particle diameter. The bimodal distributions indicated that the urban atmospheric aerosol contained an external mixture of particles with a diverse chemical composition. Particles corresponding to the NH and LV modes were assigned mainly to freshly emitted combustion particles, more specifically to vehicle emissions consisting of large mass fractions of soot likely coated with or containing some water-insoluble organic compounds such as non-hygroscopic hydrocarbon-like organics. The hygroscopic

  11. Wintertime hygroscopicity and volatility of ambient urban aerosol particles

    Directory of Open Access Journals (Sweden)

    J. Enroth

    2018-04-01

    Full Text Available Hygroscopic and volatile properties of atmospheric aerosol particles with dry diameters of (20, 50, 75, 110 and 145 nm were determined in situ by using a volatility–hygroscopicity tandem differential mobility analyser (VH-TDMA system with a relative humidity of 90 % and denuding temperature of 270 °C in central Budapest during 2 months in winter 2014–2015. The probability density function of the hygroscopic growth factor (HGF showed a distinct bimodal distribution. One of the modes was characterised by an overall mean HGF of approximately 1.07 (this corresponds to a hygroscopicity parameter κ of 0.033 independently of the particle size and was assigned to nearly hydrophobic (NH particles. Its mean particle number fraction was large, and it decreased monotonically from 69 to 41 % with particle diameter. The other mode showed a mean HGF increasing slightly from 1.31 to 1.38 (κ values from 0.186 to 0.196 with particle diameter, and it was attributed to less hygroscopic (LH particles. The mode with more hygroscopic particles was not identified. The probability density function of the volatility GF (VGF also exhibited a distinct bimodal distribution with an overall mean VGF of approximately 0.96 independently of the particle size, and with another mean VGF increasing from 0.49 to 0.55 with particle diameter. The two modes were associated with less volatile (LV and volatile (V particles. The mean particle number fraction for the LV mode decreased from 34 to 21 % with particle diameter. The bimodal distributions indicated that the urban atmospheric aerosol contained an external mixture of particles with a diverse chemical composition. Particles corresponding to the NH and LV modes were assigned mainly to freshly emitted combustion particles, more specifically to vehicle emissions consisting of large mass fractions of soot likely coated with or containing some water-insoluble organic compounds such as non

  12. Size Distribution, Chemical Composition and Optical Properties of Atmospheric Dust in Israel: A Comparison of Urban and Desert Aerosols under Clear and Dusty Conditions.

    Science.gov (United States)

    1980-02-01

    counter (Royco 220). The instrument was calibrated with dry Latex particles of known sizes which were dispersed from a liquid suspension by the use of an...such spectra it is clear that samples from both sites contain significant amounts of gypsum, clay minerals, notably kaolin and montmorillonite clays...using a wavelength dispersive micro- probe. A comparison between aerosols from the Negev desert and Tel Aviv (under easterly flow) was conducted

  13. Modification of Local Urban Aerosol Properties by Long-Range Transport of Biomass Burning Aerosol

    Directory of Open Access Journals (Sweden)

    Iwona S. Stachlewska

    2018-03-01

    Full Text Available During August 2016, a quasi-stationary high-pressure system spreading over Central and North-Eastern Europe, caused weather conditions that allowed for 24/7 observations of aerosol optical properties by using a complex multi-wavelength PollyXT lidar system with Raman, polarization and water vapour capabilities, based at the European Aerosol Research Lidar Network (EARLINET network urban site in Warsaw, Poland. During 24–30 August 2016, the lidar-derived products (boundary layer height, aerosol optical depth, Ångström exponent, lidar ratio, depolarization ratio were analysed in terms of air mass transport (HYSPLIT model, aerosol load (CAMS data and type (NAAPS model and confronted with active and passive remote sensing at the ground level (PolandAOD, AERONET, WIOS-AQ networks and aboard satellites (SEVIRI, MODIS, CATS sensors. Optical properties for less than a day-old fresh biomass burning aerosol, advected into Warsaw’s boundary layer from over Ukraine, were compared with the properties of long-range transported 3–5 day-old aged biomass burning aerosol detected in the free troposphere over Warsaw. Analyses of temporal changes of aerosol properties within the boundary layer, revealed an increase of aerosol optical depth and Ångström exponent accompanied by an increase of surface PM10 and PM2.5. Intrusions of advected biomass burning particles into the urban boundary layer seem to affect not only the optical properties observed but also the top height of the boundary layer, by moderating its increase.

  14. Determination of the columnar aerosol size distribution by inversion of spectral aerosol optical depth measurements at different areas in Egypt

    International Nuclear Information System (INIS)

    EI-Metwally, M.; Madkour, M.A.

    2006-01-01

    Aerosols have a great effects on nuclear safety calculations and atmospheric environment. The aerosol optical depth measurements are carried out at four areas in Egypt: Cairo and Helwan as urban/industrial areas, Aswan as an arid area and Mansoura as an agricultural area covering the period from Jun 1992 to May 1993. These measurements were recorded by ground-based pyrheliometers with large band-pass filters. Monthly average values of aerosol optical depth (AOD) showed a pronounced temporal trend, with a maximum AOD during summer and the transition seasons (spring and autumn) at all sites. Levels of AODs are higher at both urban and industrial areas than at other areas. Variation of Angstrom exponent a with the AOD was clear at most sites and the a value depends on the spectral range used in its determination. The mean contribution of anthropogenic sources to AOD over Cairo was at the range of 25.1-54.3%, whereas those values in Helwan were at the range of 34.5-59.8%. Finally, columnar aerosol size distributions have been inferred by inverting particularly AOD measurements as a function of wavelength. The Junge (type I) and bimodal (type III) distributions are dominant at urban and arid areas (Cairo and Aswan), whereas mono dispersion distribution (type II) are dominant in industrial and agricultural areas (Helwan and Mansoura). In Cairo and Aswan, the peak of columnar size distribution for the fine mode at radius r is around 0.1 and 0.2 μm respectively, while it is around 1.0 and 2.0 μm for the coarse mode. .Also, the peak of size distribution for the mono dispersion mode was marked at radius around 0.2 μm at both Helwan and Mansoura. A comprehensive comparison of our results with literature size distributions is very sparse, nevertheless, our size distributions in general agree with them

  15. Contrasting aerosol optical and radiative properties between dust and urban haze episodes in megacities of Pakistan

    Science.gov (United States)

    Iftikhar, Muhammad; Alam, Khan; Sorooshian, Armin; Syed, Waqar Adil; Bibi, Samina; Bibi, Humera

    2018-01-01

    Satellite and ground based remote sensors provide vital information about aerosol optical and radiative properties. Analysis of aerosol optical and radiative properties during heavy aerosol loading events in Pakistan are limited and, therefore, require in-depth examination. This work examines aerosol properties and radiative forcing during Dust Episodes (DE) and Haze Episodes (HE) between 2010 and 2014 over mega cities of Pakistan (Karachi and Lahore). Episodes having the daily averaged values of Aerosol Optical Depth (AOD) exceeding 1 were selected. DE were associated with high AOD and low Ångström Exponent (AE) over Karachi and Lahore while high AOD and high AE values were associated with HE over Lahore. Aerosol volume size distributions (AVSD) exhibited a bimodal lognormal distribution with a noticeable coarse mode peak at a radius of 2.24 μm during DE, whereas a fine mode peak was prominent at a radius 0.25 μm during HE. The results reveal distinct differences between HE and DE for spectral profiles of several parameters including Single Scattering Albedo (SSA), ASYmmetry parameter (ASY), and the real and imaginary components of refractive index (RRI and IRI). The AOD-AE correlation revealed that dust was the dominant aerosol type during DE and that biomass burning and urban/industrial aerosol types were pronounced during HE. Aerosol radiative forcing (ARF) was estimated using the Santa Barbra DISORT Atmospheric Radiative Transfer (SBDART) model. Calculations revealed a negative ARF at the Top Of the Atmosphere (ARFTOA) and at the Bottom Of the Atmosphere (ARFBOA), with positive ARF within the Atmosphere (ARFATM) during both DE and HE over Karachi and Lahore. Furthermore, estimations of ARFATM by SBDART were shown to be in good agreement with values derived from AERONET data for DE and HE over Karachi and Lahore.

  16. Sources and composition of urban aerosol particles

    Science.gov (United States)

    Vogt, M.; Johansson, C.; Mårtensson, M.; Struthers, H.; Ahlm, L.; Nilsson, D.

    2011-09-01

    From May 2008 to March 2009 aerosol emissions were measured using the eddy covariance method covering the size range 0.25 to 2.5 μm diameter (Dp) from a 105 m tower, in central Stockholm, Sweden. Supporting chemical aerosol data were collected at roof and street level. Results show that the inorganic fraction of sulfate, nitrate, ammonium and sea salt accounts for approximately 15% of the total aerosol mass removed at 0.6 μm Dp. Further heating to 300 °C caused very little additional losses road traffic (as inferred from the ratio of the incremental concentrations of nitrogen oxides (NOx) and BC measured on a densely trafficked street) and the fluxes of non-volatile material at tower level are in close agreement, suggesting a traffic source of BC. We have estimated the emission factors (EFs) for non-volatile particles <0.6 μm Dp to be 2.4±1.4 mg veh-1 km-1 based on either CO2 fluxes or traffic activity data. Light (LDV) and heavy duty vehicle (HDV) EFs were estimated using multiple linear regression and reveal that for non-volatile particulate matter in the 0.25 to 0.6 μm Dp range, the EFHDV is approximately twice as high as the EFLDV, the difference not being statistically significant.

  17. Time resolved aerosol monitoring in the urban centre of Soweto

    Science.gov (United States)

    Formenti, P.; Annegarn, H. J.; Piketh, S. J.

    1998-03-01

    A programme of aerosol sampling was conducted from 1982 to 1984 in the urban area of Soweto, Johannesburg, South Africa. The particulate matter (aerodynamic diameter source apportionment of crustal elements between coal smoke and traffic induced road dust, based on chemical elemental measurements. A novel technique is demonstrated for processing PIXE-derived time sequence elemental concentration vectors. Slowly varying background components have been extracted from sulphur and crustal aerosol components, using alternatively two digital filters: a moving minimum, and a moving average. The residuals of the crustal elements, assigned to locally generated aerosol components, were modelled using surrogate tracers: sulphur as a surrogate for coal smoke; and Pb as a surrogate for traffic activity. Results from this source apportionment revealed coal emissions contributed between 40% and 50% of the aerosol mineral matter, while 18-22% originated from road dust. Background aerosol, characteristic of the regional winter aerosol burden over the South African Highveld, was between 12% and 21%. Minor contributors identified included a manganese smelter, located 30 km from the sampling site, and informal trash burning, as the source of intermittent heavy metals (Cu, Zn). Elemental source profiles derived for these various sources are presented.

  18. Size distributions of aerosols produced from substitute materials by the Laskin cold DOP aerosol generator

    International Nuclear Information System (INIS)

    Hinds, W.; Macher, J.; First, M.W.

    1981-01-01

    Test aerosols of di(2-ethylhexyl)phthalate (DOP) produced by Laskin nozzle aerosol generators are widely used for in-place filter testing and respirator fit testing. Concern for the health effects of this material has led to a search for substitute materials for test aerosols. Aerosols were generated with a Laskin generator and diluted 6000-fold with clean air. Size distributions were measured for DOP, di(2-ethylhexyl)sebecate, polyethylene glycol, mineral oil, and corn oil aerosols with a PMS ASAS-X optical particle counter. Distributions were slightly bimodal with count median diameters from 0.22 to 0.30 μm. Size distributions varied little with aerosol material, operating pressure, or liquid level. Mineral oil and corn oil gave the best agreement with the DOP size distribution

  19. Microphysical and optical properties of aerosol particles in urban zone during ESCOMPTE

    Science.gov (United States)

    Mallet, M.; Roger, J. C.; Despiau, S.; Dubovik, O.; Putaud, J. P.

    2003-10-01

    Microphysical and optical properties of the main aerosol species on a peri-urban site have been investigated during the ESCOMPTE experiment. Ammonium sulfate (AS), nitrate (N), black carbon (BC), particulate organic matter (POM), sea salt (SS) and mineral aerosol (D) size distributions have been used, associated with their refractive index, to compute, from the Mie theory, the key radiative aerosol properties as the extinction coefficient Kext, the mass extinction efficiencies σext, the single scattering albedo ω0 and the asymmetry parameter g at the wavelength of 550 nm. Optical computations show that 90% of the light extinction is due to anthropogenic aerosol and only 10% is due to natural aerosol (SS and D). 44±6% of the extinction is due to (AS) and 40±6% to carbonaceous particles (20±4% to BC and 21±4% to POM). Nitrate aerosol has a weak contribution of 5±2%. Computations of the mass extinction efficiencies σext, single scattering albedo ω0 and asymmetry parameter g indicate that the optical properties of the anthropogenic aerosol are often quite different from those yet published and generally used in global models. For example, the (AS) mean specific mass extinction presents a large difference with the value classically adopted at low relative humidity ( h<60%) (2.6±0.5 instead of 6 m 2 g -1 at 550 nm). The optical properties of the total aerosol layer, including all the aerosol species, indicate a mean observed single-scattering albedo ω0=0.85±0.05, leading to an important absorption of the solar radiation and an asymmetry parameter g=0.59±0.05 which are in a reasonably good agreements with the AERONET retrieval of ω0 (=0.86±0.05) and g (=0.64±0.05) at this wavelength.

  20. Modeling and measurements of urban aerosol processes on the neighborhood scale in Rotterdam, Oslo and Helsinki

    Science.gov (United States)

    Karl, Matthias; Kukkonen, Jaakko; Keuken, Menno P.; Lützenkirchen, Susanne; Pirjola, Liisa; Hussein, Tareq

    2016-04-01

    This study evaluates the influence of aerosol processes on the particle number (PN) concentrations in three major European cities on the temporal scale of 1 h, i.e., on the neighborhood and city scales. We have used selected measured data of particle size distributions from previous campaigns in the cities of Helsinki, Oslo and Rotterdam. The aerosol transformation processes were evaluated using the aerosol dynamics model MAFOR, combined with a simplified treatment of roadside and urban atmospheric dispersion. We have compared the model predictions of particle number size distributions with the measured data, and conducted sensitivity analyses regarding the influence of various model input variables. We also present a simplified parameterization for aerosol processes, which is based on the more complex aerosol process computations; this simple model can easily be implemented to both Gaussian and Eulerian urban dispersion models. Aerosol processes considered in this study were (i) the coagulation of particles, (ii) the condensation and evaporation of two organic vapors, and (iii) dry deposition. The chemical transformation of gas-phase compounds was not taken into account. By choosing concentrations and particle size distributions at roadside as starting point of the computations, nucleation of gas-phase vapors from the exhaust has been regarded as post tail-pipe emission, avoiding the need to include nucleation in the process analysis. Dry deposition and coagulation of particles were identified to be the most important aerosol dynamic processes that control the evolution and removal of particles. The error of the contribution from dry deposition to PN losses due to the uncertainty of measured deposition velocities ranges from -76 to +64 %. The removal of nanoparticles by coagulation enhanced considerably when considering the fractal nature of soot aggregates and the combined effect of van der Waals and viscous interactions. The effect of condensation and

  1. Modeling and measurements of urban aerosol processes on the neighborhood scale in Rotterdam, Oslo and Helsinki

    Directory of Open Access Journals (Sweden)

    M. Karl

    2016-04-01

    Full Text Available This study evaluates the influence of aerosol processes on the particle number (PN concentrations in three major European cities on the temporal scale of 1 h, i.e., on the neighborhood and city scales. We have used selected measured data of particle size distributions from previous campaigns in the cities of Helsinki, Oslo and Rotterdam. The aerosol transformation processes were evaluated using the aerosol dynamics model MAFOR, combined with a simplified treatment of roadside and urban atmospheric dispersion. We have compared the model predictions of particle number size distributions with the measured data, and conducted sensitivity analyses regarding the influence of various model input variables. We also present a simplified parameterization for aerosol processes, which is based on the more complex aerosol process computations; this simple model can easily be implemented to both Gaussian and Eulerian urban dispersion models. Aerosol processes considered in this study were (i the coagulation of particles, (ii the condensation and evaporation of two organic vapors, and (iii dry deposition. The chemical transformation of gas-phase compounds was not taken into account. By choosing concentrations and particle size distributions at roadside as starting point of the computations, nucleation of gas-phase vapors from the exhaust has been regarded as post tail-pipe emission, avoiding the need to include nucleation in the process analysis. Dry deposition and coagulation of particles were identified to be the most important aerosol dynamic processes that control the evolution and removal of particles. The error of the contribution from dry deposition to PN losses due to the uncertainty of measured deposition velocities ranges from −76 to +64 %. The removal of nanoparticles by coagulation enhanced considerably when considering the fractal nature of soot aggregates and the combined effect of van der Waals and viscous interactions. The effect of

  2. The influence of background aerosol on spectral transparency of urban air

    International Nuclear Information System (INIS)

    Ismayilov, F.I.

    2009-01-01

    The relations between distribution of city aerosol particles on dimensions and spectral transparency of aerosol layer of atmospheric air pollution in Baku city conditions. The power and logarithmically normal functions are used for city aerosol modeling

  3. Environmental pollution due to black carbon aerosols and its impacts in a tropical urban city

    Energy Technology Data Exchange (ETDEWEB)

    Madhavi Latha, K. [National Remote Sensing Agency, Department of Space-Government of India, Balanagar, Hyderabad 500 037 (India); Badarinath, K.V.S. [National Remote Sensing Agency, Department of Space-Government of India, Balanagar, Hyderabad 500 037 (India)]. E-mail: badrinath_kvs@nrsa.gov.in

    2005-05-15

    Black carbon (BC) has become the subject of interest in the recent years for a variety of reasons. BC aerosol may cause environmental as well as harmful health effects in densely inhabited regions. BC is a strong absorber of radiation in the visible and near-infrared part of the spectrum, where most of the solar energy is distributed. Black carbon is emitted into the atmosphere as a byproduct of all combustion processes, viz., vegetation burning, industrial effluents, motor vehicle exhausts, etc. In this paper, we present results from our measurements on BC aerosols, total aerosol mass concentration, and aerosol optical depth over an urban environment, namely Hyderabad during January-May, 2003. Diurnal variations of BC suggest that high BC concentrations are observed during 6:00-9:00 h and 19:00-23:00 h. Weekday variations of BC suggest that the day average BC concentrations increases gradually from Monday to Wednesday and gradually decreases from Thursday to Sunday. Fraction of BC to total mass concentration has been observed to be 7%. BC showed positive correlation with total mass concentration and aerosol optical depth at 500 nm. Radiative transfer calculations suggest that during January-May, diurnal averaged aerosol forcing at the surface was calculated to be -33 Wm{sup -2} and at the top of the atmosphere (TOA) it is to be +9 Wm{sup -2}.

  4. Quantitative characterization of urban sources of organic aerosol by high-resolution gas chromatography

    International Nuclear Information System (INIS)

    Hildemann, L.M.; Mazurek, M.A.; Cass, G.R.; Simoneit, B.R.T.

    1991-01-01

    Fine aerosol emissions have been collected from a variety of urban combustion sources, including an industrial boiler, a fireplace, automobiles, diesel trucks, gas-fired home appliances, and meat cooking operations, by use of a dilution sampling system. Other sampling techniques have been utilized to collect fine aerosol samples of paved road dust, brake wear, tire wear, cigarette smoke, tar pot emissions, and vegetative detritus. The organic matter contained in each of these samples has been analyzed via high-resolution gas chromatography. By use of a simple computational approach, a quantitative, 50-parameter characterization of the elutable fine organic aerosol emitted from each source type has been determined. The organic mass distribution fingerprints obtained by this approach are shown to differ significantly from each other for most of the source types tested, using hierarchical cluster analysis

  5. Aerosol Number Concentrations and Visibility during Dense Fog over a Subtropical Urban Site

    Directory of Open Access Journals (Sweden)

    Manju Mohan

    2014-01-01

    Full Text Available There is now enough evidence of greater frequencies and extent of fog formation in urban areas. These could easily be linked to rapid increase in aerosol number concentration (ANC peculiar to polluted urban environments. It is therefore pertinent to study ANC and visibility alongside the meteorological parameters in order to investigate the relationships which may possibly exist between these parameters especially during foggy conditions. This study based on field measurements of ANC for aerosol spectrum varying from 0.3 µm to 20 µm attempts to investigates whether a threshold ANC could be associated with a given visibility range during low visibility conditions including dense fog episodes. Thus, the present work explores relationship between ANC size spectrum and visibility (100 m–4500 m in a polluted urban environment in India with specific reference to episodes of dense fog during winter period. The study depicts a threshold minimum value of ANC during foggy conditions. A power relationship between ANC and visibility is obtained. Further, aerosol number distribution and size distribution function are also studied and empirical relation is compared with previous studies. Further work is suggested to strengthen the findings presented here.

  6. Aerosol Delivery for Amendment Distribution in Contaminated Vadose Zones

    Science.gov (United States)

    Hall, R. J.; Murdoch, L.; Riha, B.; Looney, B.

    2011-12-01

    Remediation of contaminated vadose zones is often hindered by an inability to effectively distribute amendments. Many amendment-based approaches have been successful in saturated formations, however, have not been widely pursued when treating contaminated unsaturated materials due to amendment distribution limitations. Aerosol delivery is a promising new approach for distributing amendments in contaminated vadose zones. Amendments are aerosolized and injected through well screens. During injection the aerosol particles are transported with the gas and deposited on the surfaces of soil grains. Resulting distributions are radially and vertically broad, which could not be achieved by injecting pure liquid-phase solutions. The objectives of this work were A) to characterize transport and deposition behaviors of aerosols; and B) to develop capabilities for predicting results of aerosol injection scenarios. Aerosol transport and deposition processes were investigated by conducting lab-scale injection experiments. These experiments involved injection of aerosols through a 2m radius, sand-filled wedge. A particle analyzer was used to measure aerosol particle distributions with time, and sand samples were taken for amendment content analysis. Predictive capabilities were obtained by constructing a numerical model capable of simulating aerosol transport and deposition in porous media. Results from tests involving vegetable oil aerosol injection show that liquid contents appropriate for remedial applications could be readily achieved throughout the sand-filled wedge. Lab-scale tests conducted with aqueous aerosols show that liquid accumulation only occurs near the point of injection. Tests were also conducted using 200 g/L salt water as the aerosolized liquid. Liquid accumulations observed during salt water tests were minimal and similar to aqueous aerosol results. However, particles were measured, and salt deposited distal to the point of injection. Differences between

  7. Radioactive Aerosol Size Distribution Measured in Nuclear Workplaces

    International Nuclear Information System (INIS)

    Kravchik, T.; Oved, S.; German, U.

    2002-01-01

    Inhalation is the main route for internal exposure of workers to radioactive aerosols in the nuclear industry.Aerosol's size distribution and in particular its activity median aerodynamic diameter (AMAD)is important for determining the fractional deposition of inhaled particles in the respiratory tract and the resulting doses. Respiratory tract models have been published by the International Commission on radiological Protection (ICRP).The former model has recommended a default AMAD of 1 micron for the calculation of dose coefficients for workers in the nuclear industry [1].The recent model recommends a 5 microns default diameter for occupational exposure which is considered to be more representative of workplace aerosols [2]. Several researches on radioactive aerosol's size distribution in nuclear workplaces has supported this recommendation [3,4].This paper presents the results of radioactive aerosols size distribution measurements taken at several workplaces of the uranium production process

  8. [Ozone concentration distribution of urban].

    Science.gov (United States)

    Yin, Yong-quan; Li, Chang-mei; Ma, Gui-xia; Cui, Zhao-jie

    2004-11-01

    The increase of ozone concentration in urban is one of the most important research topics on environmental science. With the increase of nitrogen oxides and hydrogen-carbon compounds which are exhausted from cars, the ozone concentration in urban is obviously increased on sunlight, and threat of photochemistry smog will be possible. Therefore, it is very important to monitor and study the ozone concentration distribution in urban. The frequency-distribution, diurnal variation and monthly variation of ozone concentration were studied on the campus of Shandong University during six months monitoring. The influence of solar radiation and weather conditions on ozone concentration were discussed. The frequency of ozone concentration less than 200 microg/m3 is 96.88%. The ozone concentration has an obvious diurnal variation. The ozone concentration in the afternoon is higher than in the morning and in the evening. The maximum appears in June, when it is the strong solar radiation and high air-temperature. The weather conditions also influence the ozone concentration. The ozone concentration in clear day is higher than in rainy and cloudy day.

  9. Measurement of size distribution for 220Rn progeny attached aerosols

    International Nuclear Information System (INIS)

    Zhang Lei; Guo Qiuju; Zhuo Weihai

    2008-01-01

    The size distribution of radioactive aerosols is a very important factor for evaluating the inner exposure dose contributed by radon and thoron progeny in environments. In order to measure the size distribution of thoron progeny attached radioactive aerosols, a device was developed using wire screens. The count median diameter (CMD) and the geometric standard deviation (GSD) of attached radioactive aerosols were calculated by collecting ThB and using CR-39 as detector. Field measurement results at Yangjiang City in Guangdong Province show that the CMDs distribute between 30 and 130 nm, and the GSDs are between 1.9 and 3.3. It also shows that the more humid country, the smaller CMDs, and the ventilation has great influence on the size distribution of aerosols. The CMDs of adobe house are smaller than that of the concrete houses. (authors)

  10. Methods of analysis for complex organic aerosol mixtures from urban emission sources of particulate carbon

    International Nuclear Information System (INIS)

    Mazurek, M.A.; Hildemann, L.M.; Simoneit, B.R.T.

    1990-10-01

    Organic aerosols comprise approximately 30% by mass of the total fine particulate matter present in urban atmospheres. The chemical composition of such aerosols is complex and reflects input from multiple sources of primary emissions to the atmosphere, as well as from secondary production of carbonaceous aerosol species via photochemical reactions. To identify discrete sources of fine carbonaceous particles in urban atmospheres, analytical methods must reconcile both bulk chemical and molecular properties of the total carbonaceous aerosol fraction. This paper presents an overview of the analytical protocol developed and used in a study of the major sources of fine carbon particles emitted to an urban atmosphere. 23 refs., 1 fig., 2 tabs

  11. Carbonaceous content of atmospheric aerosols in Lisbon urban atmosphere

    Science.gov (United States)

    Mirante, Fátima; Oliveira, C.; Martins, N.; Pio, C.; Caseiro, A.; Cerqueira, M.; Alves, C.; Oliveira, C.; Oliveira, J.; Camões, F.; Matos, M.; Silva, H.

    2010-05-01

    Lisbon is the capital city of Portugal with about 565,000 residents and a population density of 6,600 inhabitants per square kilometre. The town is surrounded by satellite cities, forming together a region known as "Lisbon Metropolitan Area" with about 3 million inhabitants. It is estimated that more than one million citizens come into the Lisbon area every day from the outskirts, leading to elevated traffic densities and intense traffic jams. Airborne particulate matter limit values are frequently exceeded, with important consequences on air pollution levels and obvious negative impacts on human health. Atmospheric aerosols are known to have in their structure significant amounts of carbonaceous material. The knowledge of the aerosols carbon content, particularly on their several carbon forms (as TC, EC and OC, meaning respectively Total, Elemental and Organic carbon) is often required to provide information for source attribution. In order to assess the vehicles PM input, two sampling campaigns (summer and winter periods) were carried out in 2008 in Lisbon in two contrasting sites, a roadside and an urban background site. Particulate matter was collected in two fractions on quartz fibre filters using Hi-Vol samplers (coarse fraction, 2.5µmwork was performed under Project PAHLIS (Polycyclic Aromatic Hydrocarbons Contamination in Lisbon Urban Atmosphere - PTDC/AMB/65699/2006) financed by "Fundação para a Ciência e a Tecnologia" - FCT. Fátima Mirante acknowledges FCT her PhD grant (SFRH/BD/45473/2008).

  12. Changes in the physico-chemical properties of Amazonian aerosols from background conditions due to urban impacts in Central Amazonia.

    Science.gov (United States)

    Artaxo, P.; Barbosa, H. M.; Brito, J.; Carbone, S.; Fiorese, C.; Andre, B.; Rizzo, L. V.; Ditas, F.; Pöhlker, C.; Pöhlker, M. L.; Saturno, J.; Holanda, B. A.; Wang, J.; Souza, R. A. F. D.; Machado, L.; Andreae, M. O.; Martin, S. T.

    2016-12-01

    The GoAmazon 2014/15 experiment (Observations and Modeling of the Green Ocean Amazon) was a great opportunity to study how urbanization can change aerosol properties under pristine conditions in a tropical rain forest. The experiment took place from January 2014 to December 2015 in the vicinity of Manaus, Brazil, where several sampling stations were operated. Natural biogenic aerosol properties were studied in 3 sampling stations upwind of Manaus (ATTO (T0a), ZF2 (T0z) and EMBRAPA (T0e)). Urban impacted aerosols were analysed in two downwind sampling stations at Tiwa (T2) and Manacapuru (T3). Properties analysed were size distribution, scattering and absorption, composition, vertical profiles and others. Remote sensing measurements were done using AERONET and MODIS, while extensive ground based measurements were done in all sampling stations. Remote sensing measurements shows important changes in aerosol optical depth (AOD), especially in the aerosol absorption component. It was also observed a reduction in cloud droplet size downwind of Manaus for liquid phase clouds. Changes in particle number and size were also very significant, that reflected in changes in the aerosol radiative forcing (RF) before and after Manaus plume. In the dry season, an average RF of -24 w/m² was observed upwind, while -17 w/m² was observed downwind, due to large scale biomass burning aerosols. Single scattering albedo (SSA) at 550 nm changed from a high value of 0.96 upwind to 0.84 downwind due to the increase in absorbing aerosols in the wet season. In the dry season, SSA at 550nm changed from 0.95 to 0.87. Aerosol composition showed a large dominance of organic aerosols for all sites, accounting for 65-75% of PM1 non refractory aerosol. Most of these were secondary organic aerosol (SOA), with very low sulfate and nitrate concentrations. The influence of the Manaus plume on aerosol properties was more intense during the wet season, because in the dry season a significant amount of

  13. Physical and chemical characterization of urban winter-time aerosols by mobile measurements in Helsinki, Finland

    Science.gov (United States)

    Pirjola, Liisa; Niemi, Jarkko V.; Saarikoski, Sanna; Aurela, Minna; Enroth, Joonas; Carbone, Samara; Saarnio, Karri; Kuuluvainen, Heino; Kousa, Anu; Rönkkö, Topi; Hillamo, Risto

    2017-06-01

    A two-week measurement campaign by a mobile laboratory van was performed in urban environments in the Helsinki metropolitan area, Finland, in winter 2012, to obtain a comprehensive view on aerosol properties and sources. The abundances and physico-chemical properties of particles varied strongly in time and space, depending on the main sources of aerosols. Four major types of winter aerosol were recognized: 1) clean background aerosol with low particle number (Ntot) and lung deposited surface area (LDSA) concentrations due to marine air flows from the Atlantic Ocean; 2) long-range transported (LRT) pollution aerosol due to air flows from eastern Europe where the particles were characterized by the high contribution of oxygenated organic aerosol (OOA) and inorganic species, particularly sulphate, but low BC contribution, and their size distribution possessed an additional accumulation mode; 3) fresh smoke plumes from residential wood combustion in suburban small houses, these particles were characterized by high biomass burning organic aerosol (BBOA) and black carbon (BC) concentrations; and 4) fresh emissions from traffic while driving on busy streets in the city centre and on the highways during morning rush hours. This aerosol was characterized by high concentration of Ntot, LDSA, small particles in the nucleation mode, as well as high hydrocarbon-like organic aerosol (HOA) and BC concentrations. In general, secondary components (OOA, NO3, NH4, and SO4) dominated the PM1 chemical composition during the LRT episode accounting for 70-80% of the PM1 mass, whereas fresh primary emissions (BC, HOA and BBOA) dominated the local traffic and wood burning emissions. The major individual particle types observed with electron microscopy analysis (TEM/EDX) were mainly related to residential wood combustion (K/S/C-rich, soot, other C-rich particles), traffic (soot, Si/Al-rich, Fe-rich), heavy fuel oil combustion in heat plants or ships (S with V-Ni-Fe), LRT pollutants (S

  14. Improved MODIS aerosol retrieval in urban areas using a land classification approach and empirical orthogonal functions

    Science.gov (United States)

    Levitan, Nathaniel; Gross, Barry

    2016-10-01

    New, high-resolution aerosol products are required in urban areas to improve the spatial coverage of the products, in terms of both resolution and retrieval frequency. These new products will improve our understanding of the spatial variability of aerosols in urban areas and will be useful in the detection of localized aerosol emissions. Urban aerosol retrieval is challenging for existing algorithms because of the high spatial variability of the surface reflectance, indicating the need for improved urban surface reflectance models. This problem can be stated in the language of novelty detection as the problem of selecting aerosol parameters whose effective surface reflectance spectrum is not an outlier in some space. In this paper, empirical orthogonal functions, a reconstruction-based novelty detection technique, is used to perform single-pixel aerosol retrieval using the single angular and temporal sample provided by the MODIS sensor. The empirical orthogonal basis functions are trained for different land classes using the MODIS BRDF MCD43 product. Existing land classification products are used in training and aerosol retrieval. The retrieval is compared against the existing operational MODIS 3 KM Dark Target (DT) aerosol product and co-located AERONET data. Based on the comparison, our method allows for a significant increase in retrieval frequency and a moderate decrease in the known biases of MODIS urban aerosol retrievals.

  15. [Size distributions of aerosol during the Spring Festival in Nanjing].

    Science.gov (United States)

    Wang, Hong-Lei; Zhu, Bin; Shen, Li-Juan; Liu, Xiao-Hui; Zhang, Ze-Feng; Yang, Yang

    2014-02-01

    In order to investigate the firework burning impacts on spectrum distribution of atmospheric aerosol during the Spring Festival in Nanjing, number concentration and mass concentration of aerosol as well as mass concentration of gas pollutants were measured during January 19-31, 2012. The results indicated that the concentration of aerosol between 10-20 nm decreased, aerosol concentration in the range of 50-100 nm, 100-200 nm and 200-500 nm increased during the firework burning period comparing to those during the non-burning period. However, there was no obvious variation for aerosol between 20-50 nm and 0.5-10 microm. The spectrum distribution of number concentration was bimodal during the non-burning period and unimodal during the burning period, with the peak value shifting to large diameter section. The mass concentration presented a bimodal distribution, the value of PM2.5/PM10 and PM10/PM10 increased by 10% during the burning period. The firework burning events had big influence on the density of aerosol between 1.0-2.1 microm.

  16. Elemental composition of urban aerosol collected in Florence, Italy

    International Nuclear Information System (INIS)

    Lucarelli, F.; Mando, P.A.; Nava, S.; Prati, P.; Zucchiatti, A.

    2000-01-01

    An extensive investigation is in progress aiming at the characterisation of the air particulate composition in Florence. The aim is to determine the aerosol elemental concentrations as well to identify pollution sources. For our investigation, we use the external PIXE-PIGE beam facility of the Van de Graaff accelerator of INFN at the Physics Department of the Florence University. We report here an overview of the results of the PIXE analysis of a long temporal series (about 1 yr) of PM 10 particulate collected on Millipore filters on a daily basis in three different sites (characterised by different urban settings). Daily concentrations of more than 20 elements have been obtained. From the observed elemental concentrations seasonal variation were found. A relevant decrease of S, Pb and Br levels has been found with respect to 10 yr ago. Four main sources (traffic, sulphates, soil-dust and wind-transported sea-salt) have been extracted with the help of factor analysis

  17. Optical Properties of the Urban Aerosol Particles Obtained from Ground Based Measurements and Satellite-Based Modelling Studies

    Directory of Open Access Journals (Sweden)

    Genrik Mordas

    2015-01-01

    Full Text Available Applications of satellite remote sensing data combined with ground measurements and model simulation were applied to study aerosol optical properties as well as aerosol long-range transport under the impact of large scale circulation in the urban environment in Lithuania (Vilnius. Measurements included the light scattering coefficients at 3 wavelengths (450, 550, and 700 nm measured with an integrating nephelometer and aerosol particle size distribution (0.5–12 μm and number concentration (Dpa > 0.5 μm registered by aerodynamic particle sizer. Particle number concentration and mean light scattering coefficient varied from relatively low values of 6.0 cm−3 and 12.8 Mm−1 associated with air masses passed over Atlantic Ocean to relatively high value of 119 cm−3 and 276 Mm−1 associated with South-Western air masses. Analysis shows such increase in the aerosol light scattering coefficient (276 Mm−1 during the 3rd of July 2012 was attributed to a major Sahara dust storm. Aerosol size distribution with pronounced coarse particles dominance was attributed to the presence of dust particles, while resuspended dust within the urban environment was not observed.

  18. The statistical distribution of aerosol properties in sourthern West Africa

    Science.gov (United States)

    Haslett, Sophie; Taylor, Jonathan; Flynn, Michael; Bower, Keith; Dorsey, James; Crawford, Ian; Brito, Joel; Denjean, Cyrielle; Bourrianne, Thierry; Burnet, Frederic; Batenburg, Anneke; Schulz, Christiane; Schneider, Johannes; Borrmann, Stephan; Sauer, Daniel; Duplissy, Jonathan; Lee, James; Vaughan, Adam; Coe, Hugh

    2017-04-01

    The population and economy in southern West Africa have been growing at an exceptional rate in recent years and this trend is expected to continue, with the population projected to more than double to 800 million by 2050. This will result in a dramatic increase in anthropogenic pollutants, already estimated to have tripled between 1950 and 2000 (Lamarque et al., 2010). It is known that aerosols can modify the radiative properties of clouds. As such, the entrainment of anthropogenic aerosol into the large banks of clouds forming during the onset of the West African Monsoon could have a substantial impact on the region's response to climate change. Such projections, however, are greatly limited by the scarcity of observations in this part of the world. As part of the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) project, three research aircraft were deployed, each carrying equipment capable of measuring aerosol properties in-situ. Instrumentation included Aerosol Mass Spectrometers (AMS), Single Particle Soot Photometers (SP2), Condensation Particle Counters (CPC) and Scanning Mobility Particle Sizers (SMPS). Throughout the intensive aircraft campaign, 155 hours of scientific flights covered an area including large parts of Benin, Togo, Ghana and parts of Côte D'Ivoire. Approximately 70 hours were dedicated to the measurement of cloud-aerosol interactions, with many other flights producing data contributing towards this objective. Using datasets collected during this campaign period, it is possible to build a robust statistical understanding of aerosol properties in this region for the first time, including size distributions and optical and chemical properties. Here, we describe preliminary results from aerosol measurements on board the three aircraft. These have been used to describe aerosol properties throughout the region and time period encompassed by the DACCIWA aircraft campaign. Such statistics will be invaluable for improving future

  19. Photochemical processing of organic aerosol at nearby continental sites: contrast between urban plumes and regional aerosol

    Science.gov (United States)

    Slowik, J. G.; Brook, J.; Chang, R. Y.-W.; Evans, G. J.; Hayden, K.; Jeong, C.-H.; Li, S.-M.; Liggio, J.; Liu, P. S. K.; McGuire, M.; Mihele, C.; Sjostedt, S.; Vlasenko, A.; Abbatt, J. P. D.

    2011-03-01

    As part of the BAQS-Met 2007 field campaign, Aerodyne time-of-flight aerosol mass spectrometers (ToF-AMS) were deployed at two sites in southwestern Ontario from 17 June to 11 July 2007. One instrument was located at Harrow, ON, a rural, agriculture-dominated area approximately 40 km southeast of the Detroit/Windsor/Windsor urban area and 5 km north of Lake Erie. The second instrument was located at Bear Creek, ON, a rural site approximately 70 km northeast of the Harrow site and 50 km east of Detroit/Windsor. Positive matrix factorization analysis of the combined organic mass spectral dataset yields factors related to secondary organic aerosol (SOA), direct emissions, and a factor tentatively attributed to the reactive uptake of isoprene and/or condensation of its early generation reaction products. This is the first application of PMF to simultaneous AMS measurements at different sites, an approach which allows for self-consistent, direct comparison of the datasets. Case studies are utilized to investigate processing of SOA from (1) fresh emissions from Detroit/Windsor and (2) regional aerosol during periods of inter-site flow. A strong correlation is observed between SOA/excess CO and photochemical age as represented by the NOx/NOy ratio for Detroit/Windsor outflow. Although this correlation is not evident for more aged air, measurements at the two sites during inter-site transport nevertheless show evidence of continued atmospheric processing by SOA production. However, the rate of SOA production decreases with airmass age from an initial value of ~10.1 μg m-3 ppmvCO-1 h-1 for the first ~10 h of plume processing to near-zero in an aged airmass (i.e. after several days). The initial SOA production rate is comparable to the observed rate in Mexico City over similar timescales.

  20. Persistence of urban organic aerosols composition: Decoding their structural complexity and seasonal variability

    International Nuclear Information System (INIS)

    Matos, João T.V.; Duarte, Regina M.B.O.; Lopes, Sónia P.; Silva, Artur M.S.; Duarte, Armando C.

    2017-01-01

    Organic Aerosols (OAs) are typically defined as highly complex matrices whose composition changes in time and space. Focusing on time vector, this work uses two-dimensional nuclear magnetic resonance (2D NMR) techniques to examine the structural features of water-soluble (WSOM) and alkaline-soluble organic matter (ASOM) sequentially extracted from fine atmospheric aerosols collected in an urban setting during cold and warm seasons. This study reveals molecular signatures not previously decoded in NMR-related studies of OAs as meaningful source markers. Although the ASOM is less hydrophilic and structurally diverse than its WSOM counterpart, both fractions feature a core with heteroatom-rich branched aliphatics from both primary (natural and anthropogenic) and secondary origin, aromatic secondary organics originated from anthropogenic aromatic precursors, as well as primary saccharides and amino sugar derivatives from biogenic emissions. These common structures represent those 2D NMR spectral signatures that are present in both seasons and can thus be seen as an “annual background” profile of the structural composition of OAs at the urban location. Lignin-derived structures, nitroaromatics, disaccharides, and anhydrosaccharides signatures were also identified in the WSOM samples only from periods identified as smoke impacted, which reflects the influence of biomass-burning sources. The NMR dataset on the H–C molecules backbone was also used to propose a semi-quantitative structural model of urban WSOM, which will aid efforts for more realistic studies relating the chemical properties of OAs with their atmospheric behavior. - Highlights: • 2D NMR spectroscopy was used to decode urban organic aerosols. • Water and alkaline soluble components of urban organic aerosols have been compared. • Persistence of urban organic aerosols composition across different seasons. • Annual background profile of the structural features of urban organic aerosols. • Semi

  1. Variability of aerosol vertical distribution in the Sahel

    Directory of Open Access Journals (Sweden)

    O. Cavalieri

    2010-12-01

    Full Text Available In this work, we have studied the seasonal and inter-annual variability of the aerosol vertical distribution over Sahelian Africa for the years 2006, 2007 and 2008, characterizing the different kind of aerosols present in the atmosphere in terms of their optical properties observed by ground-based and satellite instruments, and their sources searched for by using trajectory analysis. This study combines data acquired by three ground-based micro lidar systems located in Banizoumbou (Niger, Cinzana (Mali and M'Bour (Senegal in the framework of the African Monsoon Multidisciplinary Analysis (AMMA, by the AEROsol RObotic NETwork (AERONET sun-photometers and by the space-based Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP onboard the CALIPSO satellite (Cloud-Aerosol Lidar and Infrared Pathfinder Observations.

    During winter, the lower levels air masses arriving in the Sahelian region come mainly from North, North-West and from the Atlantic area, while in the upper troposphere air flow generally originates from West Africa, crossing a region characterized by the presence of large biomass burning sources. The sites of Cinzana, Banizoumbou and M'Bour, along a transect of aerosol transport from East to West, are in fact under the influence of tropical biomass burning aerosol emission during the dry season, as revealed by the seasonal pattern of the aerosol optical properties, and by back-trajectory studies.

    Aerosol produced by biomass burning are observed mainly during the dry season and are confined in the upper layers of the atmosphere. This is particularly evident for 2006, which was characterized by a large presence of biomass burning aerosols in all the three sites.

    Biomass burning aerosol is also observed during spring when air masses originating from North and East Africa pass over sparse biomass burning sources, and during summer when biomass burning aerosol is transported from the southern part of the

  2. On the Scattering Properties of Urban and Maritime Aerosols and its ...

    African Journals Online (AJOL)

    The scattering properties of aerosols play a dominant role in radiative energy transfer and consequently influencing the visibility and turbidity in the atmosphere. In the present attempt, calculations for scattered intensity have been made in case of urban and maritime aerosols in the varying conditions of relative humidity.

  3. Indoor radon progeny aerosol size measurements in urban, suburban, and rural regions

    International Nuclear Information System (INIS)

    Tu, K.W.; Knutson, E.O.; George, A.C.

    1991-01-01

    By using direct and indirect methods, the authors conducted size distribution measurements of radon progeny particles in a variety of indoor environments in urban, suburban, and rural areas. The radon progeny particle size distribution owing to indoor activities has two definable source categories: (1) gas combustion from stoves and kerosene heaters - particles were found to be smaller than 0.1 μm in diameter, mostly in the range 0.02-0.08 μm; and (2) cigarette smoking and food frying - particles were found to be larger, in the size range 0.1-0.2 μm. The radon progeny particle size distribution, without significant indoor activities, such as cooking, was found to be larger in rural areas than in urban or suburban areas. The modal diameters of the size spectra in the rural areas were two to three times larger than those in urban or suburban areas, around 0.3-0.4 bs. 0.1-0.2 μm. Results obtained by applying the attachment theory to the measured number-weighted size spectra from an electrical aerosol size analyzer support this finding. These results, if confirmed by more extensive studies, will be useful for the assessment of the risk from the inhalation of radon progeny in various indoor environments

  4. Spatial Interpolation of Aerosol Optical Depth Pollution: Comparison of Methods for the Development of Aerosol Distribution

    Science.gov (United States)

    Safarpour, S.; Abdullah, K.; Lim, H. S.; Dadras, M.

    2017-09-01

    Air pollution is a growing problem arising from domestic heating, high density of vehicle traffic, electricity production, and expanding commercial and industrial activities, all increasing in parallel with urban population. Monitoring and forecasting of air quality parameters are important due to health impact. One widely available metric of aerosol abundance is the aerosol optical depth (AOD). The AOD is the integrated light extinction coefficient over a vertical atmospheric column of unit cross section, which represents the extent to which the aerosols in that vertical profile prevent the transmission of light by absorption or scattering. Seasonal aerosol optical depth (AOD) values at 550 nm derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard NASA's Terra satellites, for the 10 years period of 2000 - 2010 were used to test 7 different spatial interpolation methods in the present study. The accuracy of estimations was assessed through visual analysis as well as independent validation based on basic statistics, such as root mean square error (RMSE) and correlation coefficient. Based on the RMSE and R values of predictions made using measured values from 2000 to 2010, Radial Basis Functions (RBFs) yielded the best results for spring, summer and winter and ordinary kriging yielded the best results for fall.

  5. SPATIAL INTERPOLATION OF AEROSOL OPTICAL DEPTH POLLUTION: COMPARISON OF METHODS FOR THE DEVELOPMENT OF AEROSOL DISTRIBUTION

    Directory of Open Access Journals (Sweden)

    S. Safarpour

    2017-09-01

    Full Text Available Air pollution is a growing problem arising from domestic heating, high density of vehicle traffic, electricity production, and expanding commercial and industrial activities, all increasing in parallel with urban population. Monitoring and forecasting of air quality parameters are important due to health impact. One widely available metric of aerosol abundance is the aerosol optical depth (AOD. The AOD is the integrated light extinction coefficient over a vertical atmospheric column of unit cross section, which represents the extent to which the aerosols in that vertical profile prevent the transmission of light by absorption or scattering. Seasonal aerosol optical depth (AOD values at 550 nm derived from the Moderate Resolution Imaging Spectroradiometer (MODIS sensor onboard NASA’s Terra satellites, for the 10 years period of 2000 - 2010 were used to test 7 different spatial interpolation methods in the present study. The accuracy of estimations was assessed through visual analysis as well as independent validation based on basic statistics, such as root mean square error (RMSE and correlation coefficient. Based on the RMSE and R values of predictions made using measured values from 2000 to 2010, Radial Basis Functions (RBFs yielded the best results for spring, summer and winter and ordinary kriging yielded the best results for fall.

  6. Water-soluble components in PM10 aerosols over an urban and a suburban site in the city of Sfax (Tunisia)

    OpenAIRE

    AZRI, C.; MABROUK, C.; ABIDA, H.; MEDHIOUB, K.

    2010-01-01

    This study examines the influence of source and meteorological factors on the physico-chemical characteristics of atmospheric aerosols collected at two sampling sites, urban and suburban, in the city of Sfax (Tunisia) during the year of 2004. Atmospheric aerosols were further analyzed for their chemical composition and spatio-temporal evolution was investigated. Based on particle content distribution, the species studied were classified into distinct groups with different content and temporal...

  7. A Merging Algorithm for Aerosol Size Distribution from Multiple Instruments

    Czech Academy of Sciences Publication Activity Database

    Ondráček, Jakub; Ždímal, Vladimír; Smolík, Jiří; Lazaridis, M.

    2009-01-01

    Roč. 199, 1-4 (2009), s. 219-233 ISSN 0049-6979 Grant - others:MTKD(XE) CT-2004-513849 Institutional research plan: CEZ:AV0Z40720504 Keywords : aerosols * merging particle size distribution * multilognormal model Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.676, year: 2009

  8. Particle size distribution of UO sub 2 aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Raghunath, B. (Radiation Safety Systems Div., BARC, Bombay (India)); Ramachandran, R.; Majumdar, S. (Radiometallurgy Div., BARC, Bombay (India))

    1991-12-01

    The Anderson cascade impactor has been used to determine the activity mean aerodynamic diameter and the particle size distribution of UO{sub 2} powders dispersed in the form of stable aerosols in an air medium. The UO{sub 2} powders obtained by the calcination of ammonium uranyl carbonate (AUC) and ammonium diuranate (ADU) precipitates have been used. (orig./MM).

  9. Photochemical processing of organic aerosol at nearby continental sites: contrast between urban plumes and regional aerosol

    Directory of Open Access Journals (Sweden)

    J. G. Slowik

    2011-03-01

    Full Text Available As part of the BAQS-Met 2007 field campaign, Aerodyne time-of-flight aerosol mass spectrometers (ToF-AMS were deployed at two sites in southwestern Ontario from 17 June to 11 July 2007. One instrument was located at Harrow, ON, a rural, agriculture-dominated area approximately 40 km southeast of the Detroit/Windsor/Windsor urban area and 5 km north of Lake Erie. The second instrument was located at Bear Creek, ON, a rural site approximately 70 km northeast of the Harrow site and 50 km east of Detroit/Windsor. Positive matrix factorization analysis of the combined organic mass spectral dataset yields factors related to secondary organic aerosol (SOA, direct emissions, and a factor tentatively attributed to the reactive uptake of isoprene and/or condensation of its early generation reaction products. This is the first application of PMF to simultaneous AMS measurements at different sites, an approach which allows for self-consistent, direct comparison of the datasets. Case studies are utilized to investigate processing of SOA from (1 fresh emissions from Detroit/Windsor and (2 regional aerosol during periods of inter-site flow. A strong correlation is observed between SOA/excess CO and photochemical age as represented by the NOx/NOy ratio for Detroit/Windsor outflow. Although this correlation is not evident for more aged air, measurements at the two sites during inter-site transport nevertheless show evidence of continued atmospheric processing by SOA production. However, the rate of SOA production decreases with airmass age from an initial value of ~10.1 μg m−3 ppmvCO−1 h−1 for the first ~10 h of plume processing to near-zero in an aged airmass (i.e. after several days. The initial SOA production rate is comparable to the observed rate in Mexico City over similar timescales.

  10. Droplet activation properties of organic aerosols observed at an urban site during CalNex-LA

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Fan [Brookhaven National Laboratory, Upton New York USA; Pacific Northwest National Laboratory, Richland Washington USA; Hayes, Patrick L. [Cooperative Institute for Research in Environmental Sciences, Boulder Colorado USA; Department of Chemistry and Biochemistry, University of Colorado, Boulder Colorado USA; Ortega, Amber [Cooperative Institute for Research in Environmental Sciences, Boulder Colorado USA; Department of Chemistry and Biochemistry, University of Colorado, Boulder Colorado USA; Taylor, Jonathan W. [School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester UK; Allan, James D. [School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester UK; National Centre for Atmospheric Science, University of Manchester, Manchester UK; Gilman, Jessica [NOAA Earth System Research Laboratory, Boulder Colorado USA; Kuster, William [NOAA Earth System Research Laboratory, Boulder Colorado USA; de Gouw, Joost [NOAA Earth System Research Laboratory, Boulder Colorado USA; Jimenez, Jose L. [Cooperative Institute for Research in Environmental Sciences, Boulder Colorado USA; Department of Chemistry and Biochemistry, University of Colorado, Boulder Colorado USA; Wang, Jian [Brookhaven National Laboratory, Upton New York USA

    2013-04-11

    Size-resolved cloud condensation nuclei (CCN) spectra and aerosol chemical composition were characterized at an urban supersite in Pasadena, California, from 15 May to 4 June 2010, during the CalNex campaign. The derived hygroscopicity (κCCN) of CCN-active particles with diameter between 97 and 165 nm ranged from 0.05 to 0.4. Diurnal variation showed a slight decrease of κCCN from 8:00 to 16:00 (from 0.24 to 0.20), which is attributed to increasing organics volume fraction resulted from secondary organic aerosol (SOA) formation. The derived hygroscopicity distribution and maximum activated fraction of the size selected particles were examined as functions of photochemical age. The result indicates that condensation of secondary species (e.g., SOA and sulfate) quickly converted hydrophobic particles to hydrophilic ones, and during daytime, nearly every particle became a CCN at ~0.4% in just a few hours. Based on κCCN and aerosol chemical composition, the organic hygroscopicity (κorg) was derived, and ranged from 0.05 to 0.23 with an average value of 0.13, consistent with the results from earlier studies. The derived κorg generally increased with the organic oxidation level, and most of the variation in κorg could be explained by the variation of the organic O : C atomic ratio alone. The least squares fit of the data yielded κorg = (0.83 ± 0.06) × (O:C) + (-0.19 ± 0.02). Compared to previous results based on CCN measurements of laboratory generated aerosols, κorg derived from measurements during the CalNex campaign exhibited stronger increase with O : C atomic ratio and therefore substantially higher values for organics with average O : C greater than 0.5.

  11. Anthropogenic influence on the distribution of tropospheric sulphate aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Langner, J; Rodhe, H; Crutzen, P J; Zimmermann, P [Swedish Meteorological and Hydrological Institute, Norrkoeping (Sweden)

    1992-10-22

    Human activities have increased global emissions of sulphur gases by about a factor of three during the past century, leading to increased sulphate aerosol concentrations, mainly in the Northern Hemisphere. Sulphate aerosols can affect the climate directly, by increasing the backscattering of solar radiation in cloud-free air, and indirectly, by providing additional cloud condensation nuclei. Here a global transport-chemistry model is used to estimate the changes in the distribution of tropospheric sulphate aerosol and deposition of non-seasalt sulphur that have occurred since pre-industrial times. The increase in sulphate aerosol concentration is small over the Southern Hemisphere oceans, but reaches a factor of 100 over northern Europe in winter. Calculations indicate, however, that at most 6% of the anthropogenic sulphur emissions is available for the formation of new aerosol particles. This is because about one-half of the sulphur dioxide is deposited on the Earth's surface, and most of the remainder is oxidized in cloud droplets so that the sulphate becomes associated with pre-existing particles. Even so, the rate of formation of new sulphate particles may have doubled since pre-industrial times. 18 refs., 3 figs.

  12. Phenomenological study of aerosol dry deposition in urban area: surface properties, turbulence and local meteorology influences

    International Nuclear Information System (INIS)

    Roupsard, P.

    2013-01-01

    Aerosol dry deposition is not much known for urban areas due to the lack of data. Knowledge on this phenomenon is necessary to understand pollutant fluxes in cities and to estimate inhabitant exposition to ionizing radiation of radioactive aerosols. A data providing could enable to enhance dry deposition models for these areas. An original experimental approach is performed to study submicron aerosol dry deposition on urban surfaces. Wind tunnel coupled to in situ experiments give results to study different physical phenomenon governing dry deposition. Dry deposition velocities are measured using aerosol tracers. These data are associated to turbulent and meteorological measured conditions. This database permits to classify the principal physical phenomenon for each experiment type. Finally, different phenomenon must be considered for chronic and acute exposition of urban surfaces to atmospheric particles. (author)

  13. Size distribution measurements and chemical analysis of aerosol components

    Energy Technology Data Exchange (ETDEWEB)

    Pakkanen, T.A.

    1995-12-31

    The principal aims of this work were to improve the existing methods for size distribution measurements and to draw conclusions about atmospheric and in-stack aerosol chemistry and physics by utilizing size distributions of various aerosol components measured. A sample dissolution with dilute nitric acid in an ultrasonic bath and subsequent graphite furnace atomic absorption spectrometric analysis was found to result in low blank values and good recoveries for several elements in atmospheric fine particle size fractions below 2 {mu}m of equivalent aerodynamic particle diameter (EAD). Furthermore, it turned out that a substantial amount of analyses associated with insoluble material could be recovered since suspensions were formed. The size distribution measurements of in-stack combustion aerosols indicated two modal size distributions for most components measured. The existence of the fine particle mode suggests that a substantial fraction of such elements with two modal size distributions may vaporize and nucleate during the combustion process. In southern Norway, size distributions of atmospheric aerosol components usually exhibited one or two fine particle modes and one or two coarse particle modes. Atmospheric relative humidity values higher than 80% resulted in significant increase of the mass median diameters of the droplet mode. Important local and/or regional sources of As, Br, I, K, Mn, Pb, Sb, Si and Zn were found to exist in southern Norway. The existence of these sources was reflected in the corresponding size distributions determined, and was utilized in the development of a source identification method based on size distribution data. On the Finnish south coast, atmospheric coarse particle nitrate was found to be formed mostly through an atmospheric reaction of nitric acid with existing coarse particle sea salt but reactions and/or adsorption of nitric acid with soil derived particles also occurred. Chloride was depleted when acidic species reacted

  14. Simulation of aerosol optical properties over a tropical urban site in India using a global model and its comparison with ground measurements

    Directory of Open Access Journals (Sweden)

    D. Goto

    2011-05-01

    Full Text Available Aerosols have great impacts on atmospheric environment, human health, and earth's climate. Therefore, information on their spatial and temporal distribution is of paramount importance. Despite numerous studies have examined the variation and trends of BC and AOD over India, only very few have focused on their spatial distribution or even correlating the observations with model simulations. In the present study, a three-dimensional aerosol transport-radiation model coupled with a general circulation model. SPRINTARS, simulated atmospheric aerosol distributions including BC and aerosol optical properties, i.e., aerosol optical thickness (AOT, Ångström Exponent (AE, and single scattering albedo (SSA. The simulated results are compared with both BC measurements by aethalometer and aerosol optical properties measured by ground-based skyradiometer and by satellite sensor, MODIS/Terra over Hyderabad, which is a tropical urban area of India, for the year 2008. The simulated AOT and AE in Hyderabad are found to be comparable to ground-based measured ones. The simulated SSA tends to be higher than the ground-based measurements. Both these comparisons of aerosol optical properties between the simulations with different emission inventories and the measurements indicate that, firstly the model uncertainties derived from aerosol emission inventory cannot explain the gaps between the simulations and the measurements and secondly the vertical transport of BC and the treatment of BC-containing particles can be the main issue in the global model to solve the gap.

  15. Size spectra for trace elements in urban aerosol particles by instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Ondov, J.M.; Divita, F. Jr.

    1993-01-01

    Size-fractionated aerosol samples collected with micro-orifice impactors at Camden, NJ, a heavily industrialized urban area, and at two sites near Washington, DC, were analyzed for elemental constituents determined instrumentally from short-lived neutron activation products. A least-squares peak-fitting method was used with impactor calibration data to determine log-normal distribution parameters, i.e., mass median aerodynamic diameter (MMAD) and geometric standard deviation (σ g ) for particles bearing S, V, Br, and I. For these elements, MMADs ranged from 0.24 to 0.65 μm; 0.23 to 0.53 μm; 0.22 to 0.61 μm, and 0.20 to 0.48 μm, respectively. (author) 15 refs.; 4 figs.; 2 tabs

  16. Atmospheric aerosol in an urban area: Comparison of measurement instruments and methodologies and pulmonary deposition assessment

    International Nuclear Information System (INIS)

    Berico, M.; Luciani, A.; Formignani, M.

    1996-07-01

    In March 1995 a measurement campaign of atmospheric aerosol in the Bologna urban area (Italy) was carried out. A transportable laboratory, set up by ENEA (Italian national Agency for New Technologies, Energy and the Environment) Environmental Department (Bologna), was utilized with instruments for measurement of atmospheric aerosol and meteorological parameters. The aim of this campaign was of dual purpose: to characterize aerosol in urban area and to compare different instruments and methodologies of measurements. Mass concentrations measurements, evaluated on a 23-hour period with total filter, PM10 dichotomous sampler and low pressure impactor (LPI Berner), have provided information respectively about total suspended particles, respirable fraction and granulometric parameters of aerosol. Eight meteorologic parameters, number concentration of submicromic fraction of aerosol and mass concentration of micromic fraction have been continually measured. Then, in a daytime period, several number granulometries of atmospheric aerosol have also been estimated by means of diffusion battery system. Results related to different measurement methodologies and granulometric characteristics of aerosol are presented here. Pulmonary deposition of atmospheric aerosol is finally calculated, using granulometries provided by LPI Brener and ICRP 66 human respiratory tract model

  17. Apportionment of urban aerosol sources in Cork (Ireland) by synergistic measurement techniques.

    Science.gov (United States)

    Dall'Osto, Manuel; Hellebust, Stig; Healy, Robert M; O'Connor, Ian P; Kourtchev, Ivan; Sodeau, John R; Ovadnevaite, Jurgita; Ceburnis, Darius; O'Dowd, Colin D; Wenger, John C

    2014-09-15

    The sources of ambient fine particulate matter (PM2.5) during wintertime at a background urban location in Cork city (Ireland) have been determined. Aerosol chemical analyses were performed by multiple techniques including on-line high resolution aerosol time-of-flight mass spectrometry (Aerodyne HR-ToF-AMS), on-line single particle aerosol time-of-flight mass spectrometry (TSI ATOFMS), on-line elemental carbon-organic carbon analysis (Sunset_EC-OC), and off-line gas chromatography/mass spectrometry and ion chromatography analysis of filter samples collected at 6-h resolution. Positive matrix factorization (PMF) has been carried out to better elucidate aerosol sources not clearly identified when analyzing results from individual aerosol techniques on their own. Two datasets have been considered: on-line measurements averaged over 2-h periods, and both on-line and off-line measurements averaged over 6-h periods. Five aerosol sources were identified by PMF in both datasets, with excellent agreement between the two solutions: (1) regional domestic solid fuel burning--"DSF_Regional," 24-27%; (2) local urban domestic solid fuel burning--"DSF_Urban," 22-23%; (3) road vehicle emissions--"Traffic," 15-20%; (4) secondary aerosols from regional anthropogenic sources--"SA_Regional" 9-13%; and (5) secondary aged/processed aerosols related to urban anthropogenic sources--"SA_Urban," 21-26%. The results indicate that, despite regulations for restricting the use of smoky fuels, solid fuel burning is the major source (46-50%) of PM2.5 in wintertime in Cork, and also likely other areas of Ireland. Whilst wood combustion is strongly associated with OC and EC, it was found that peat and coal combustion is linked mainly with OC and the aerosol from these latter sources appears to be more volatile than that produced by wood combustion. Ship emissions from the nearby port were found to be mixed with the SA_Regional factor. The PMF analysis allowed us to link the AMS cooking organic

  18. Study of Cl containing urban aerosol particles by ion beam analytical methods

    International Nuclear Information System (INIS)

    Angyal, A.; Kertesz, Zs.; Szikszai, Z.; Szoboszlai, T.

    2009-01-01

    Complete text of publication follows. In the densely populated areas of Europe one of the most important environmental problems is aerosol pollution. Thus one of the main goals of atmospheric research is to determine aerosol sources. In order to identify the origin of the particles, the knowledge of the chemical composition and size distribution is demanded. As a result of a source apportionment study, several sources of fine (particles with aerodynamic diameter < 2.5 μm) and coarse (10 μm ≥ aerodynamic diameter ≥ 2.5 μm) urban particulate matter were identified in Debrecen, using the hourly evolution of the elemental components. Sources characterized by high chlorine content were found in both size fractions, which gave significant contribution to the aerosol concentration in Debrecen. However, the origin of these particles could not be identified on the available information. In this work we give a more accurate characterization of the sources of coarse-mode Cl by using single particle analysis. Aerosol samples with 2-3 hours time resolution were collected in the frame of sampling campaigns in the garden of ATOMKI between October 2007 and January 2009. The elemental composition (for Z ≥ 13) was determined by Particle Induced X-ray Emission (PIXE). Single particle analysis of chosen samples was done on the ATOMKI Scanning Nuclear Microprobe Facility. Morphology, size and elemental composition for Z ≥ 6 of around 1000 coarse mode particles were determined by Scanning Transmission Ion Microscopy, light element PIXE and PIXE analytical methods. Hierarchical cluster analysis was performed on the data set to group the particles. In order to determine the possible sources of Cl in the coarse mode, the correlation between Cl and other elements, which could be used as tracers of different sources, was examined. Cl showed very strong correlation with Na. However the Cl:Na ratio was found to be different for different episodes indicating different origin of these

  19. Compact and portable system for evaluation of individual exposure at aerosol particle in urban area

    International Nuclear Information System (INIS)

    De Zaiacomo, T.

    1995-01-01

    A compact and portable system for real-time acquisition of aerosol concentration data in urban and extra-urban area is presented. It is based on two optical type aerosol monitors integrated by aerosol particle separating and collecting devices, assembled into a carrying case together with temperature and relative humidity sensors and a programmable analog data logger; data output is addressed to a dedicated printer or personal computer. Further data about particle size, morphological aspect and particle mass concentration are obtainable by weighing supports used to concurrently collect aerosol particles and/or by means of microanalytical techniques. System performances are evaluated from the point of view of portability, possibility of use as stationary sampler for long-term monitoring purposes and coherence between optical response and ponderal mass. Some tests are finally carried out, to investigate the effect of relative humidity on the optical response of this type of instruments

  20. Urban light pollution - The effect of atmospheric aerosols on astronomical observations at night

    Science.gov (United States)

    Joseph, Joachim H.; Mekler, Yuri; Kaufman, Yoram J.

    1991-01-01

    The transfer of diffuse city light from a localized source through a dust-laden atmosphere with optical depth less than 0.5 has been analyzed in the source-observer plane on the basis of an approximate treatment. The effect on several types of astronomical observation at night has been studied, considering different size distributions and amounts as well as particle shapes of the aerosols. The analysis is made in terms of the signal-to-noise ratios for a given amount of aerosol. The model is applied to conditions at the Wise Astronomical Observatory in the Negev desert, and limiting backgrounds for spectroscopy, photometry, and photography of stars and extended objects have been calculated for a variety of signal-to-noise ratios. Applications to observations with different equipment at various distances from an urban area of any size are possible. Due to the use of signal-to-noise ratios, the conclusions are different for the different experimental techniques used in astronomy.

  1. Identification of aerosol types over an urban site based on air-mass trajectory classification

    Science.gov (United States)

    Pawar, G. V.; Devara, P. C. S.; Aher, G. R.

    2015-10-01

    Columnar aerosol properties retrieved from MICROTOPS II Sun Photometer measurements during 2010-2013 over Pune (18°32‧N; 73°49‧E, 559 m amsl), a tropical urban station in India, are analyzed to identify aerosol types in the atmospheric column. Identification/classification is carried out on the basis of dominant airflow patterns, and the method of discrimination of aerosol types on the basis of relation between aerosol optical depth (AOD500 nm) and Ångström exponent (AE, α). Five potential advection pathways viz., NW/N, SW/S, N, SE/E and L have been identified over the observing site by employing the NOAA-HYSPLIT air mass back trajectory analysis. Based on AE against AOD500 nm scatter plot and advection pathways followed five major aerosol types viz., continental average (CA), marine continental average (MCA), urban/industrial and biomass burning (UB), desert dust (DD) and indeterminate or mixed type (MT) have been identified. In winter, sector SE/E, a representative of air masses traversed over Bay of Bengal and Eastern continental Indian region has relatively small AOD (τpλ = 0.43 ± 0.13) and high AE (α = 1.19 ± 0.15). These values imply the presence of accumulation/sub-micron size anthropogenic aerosols. During pre-monsoon, aerosols from the NW/N sector have high AOD (τpλ = 0.61 ± 0.21), and low AE (α = 0.54 ± 0.14) indicating an increase in the loading of coarse-mode particles over Pune. Dominance of UB type in winter season for all the years (i.e. 2010-2013) may be attributed to both local/transported aerosols. During pre-monsoon seasons, MT is the dominant aerosol type followed by UB and DD, while the background aerosols are insignificant.

  2. Mixing states of aerosols over four environmentally distinct atmospheric regimes in Asia: coastal, urban, and industrial locations influenced by dust.

    Science.gov (United States)

    Ramachandran, S; Srivastava, Rohit

    2016-06-01

    Mixing can influence the optical, physical, and chemical characteristics of aerosols, which in turn can modify their life cycle and radiative effects. Assumptions on the mixing state can lead to uncertain estimates of aerosol radiative effects. To examine the effect of mixing on the aerosol characteristics, and their influence on radiative effects, aerosol mixing states are determined over four environmentally distinct locations (Karachi, Gwangju, Osaka, and Singapore) in Asia, an aerosol hot spot region, using measured spectral aerosol optical properties and optical properties model. Aerosol optical depth (AOD), single scattering albedo (SSA), and asymmetry parameter (g) exhibit spectral, spatial, and temporal variations. Aerosol mixing states exhibit large spatial and temporal variations consistent with aerosol characteristics and aerosol type over each location. External mixing of aerosol species is unable to reproduce measured SSA over Asia, thus providing a strong evidence that aerosols exist in mixed state. Mineral dust (MD) (core)-Black carbon (BC) (shell) is one of the most preferred aerosol mixing states. Over locations influenced by biomass burning aerosols, BC (core)-water soluble (WS, shell) is a preferred mixing state, while dust gets coated by anthropogenic aerosols (BC, WS) over urban regions influenced by dust. MD (core)-sea salt (shell) mixing is found over Gwangju corroborating the observations. Aerosol radiative forcing exhibits large seasonal and spatial variations consistent with features seen in aerosol optical properties and mixing states. TOA forcing is less negative/positive for external mixing scenario because of lower SSA. Aerosol radiative forcing in Karachi is a factor of 2 higher when compared to Gwangju, Osaka, and Singapore. The influence of g on aerosol radiative forcing is insignificant. Results emphasize that rather than prescribing one single aerosol mixing state in global climate models regionally and temporally varying aerosol

  3. Spatial distribution analysis of the OMI aerosol layer height: a pixel-by-pixel comparison to CALIOP observations

    Science.gov (United States)

    Chimot, Julien; Pepijn Veefkind, J.; Vlemmix, Tim; Levelt, Pieternel F.

    2018-04-01

    A global picture of atmospheric aerosol vertical distribution with a high temporal resolution is of key importance not only for climate, cloud formation, and air quality research studies but also for correcting scattered radiation induced by aerosols in absorbing trace gas retrievals from passive satellite sensors. Aerosol layer height (ALH) was retrieved from the OMI 477 nm O2 - O2 band and its spatial pattern evaluated over selected cloud-free scenes. Such retrievals benefit from a synergy with MODIS data to provide complementary information on aerosols and cloudy pixels. We used a neural network approach previously trained and developed. Comparison with CALIOP aerosol level 2 products over urban and industrial pollution in eastern China shows consistent spatial patterns with an uncertainty in the range of 462-648 m. In addition, we show the possibility to determine the height of thick aerosol layers released by intensive biomass burning events in South America and Russia from OMI visible measurements. A Saharan dust outbreak over sea is finally discussed. Complementary detailed analyses show that the assumed aerosol properties in the forward modelling are the key factors affecting the accuracy of the results, together with potential cloud residuals in the observation pixels. Furthermore, we demonstrate that the physical meaning of the retrieved ALH scalar corresponds to the weighted average of the vertical aerosol extinction profile. These encouraging findings strongly suggest the potential of the OMI ALH product, and in more general the use of the 477 nm O2 - O2 band from present and future similar satellite sensors, for climate studies as well as for future aerosol correction in air quality trace gas retrievals.

  4. Spatial distribution analysis of the OMI aerosol layer height: a pixel-by-pixel comparison to CALIOP observations

    Directory of Open Access Journals (Sweden)

    J. Chimot

    2018-04-01

    Full Text Available A global picture of atmospheric aerosol vertical distribution with a high temporal resolution is of key importance not only for climate, cloud formation, and air quality research studies but also for correcting scattered radiation induced by aerosols in absorbing trace gas retrievals from passive satellite sensors. Aerosol layer height (ALH was retrieved from the OMI 477 nm O2 − O2 band and its spatial pattern evaluated over selected cloud-free scenes. Such retrievals benefit from a synergy with MODIS data to provide complementary information on aerosols and cloudy pixels. We used a neural network approach previously trained and developed. Comparison with CALIOP aerosol level 2 products over urban and industrial pollution in eastern China shows consistent spatial patterns with an uncertainty in the range of 462–648 m. In addition, we show the possibility to determine the height of thick aerosol layers released by intensive biomass burning events in South America and Russia from OMI visible measurements. A Saharan dust outbreak over sea is finally discussed. Complementary detailed analyses show that the assumed aerosol properties in the forward modelling are the key factors affecting the accuracy of the results, together with potential cloud residuals in the observation pixels. Furthermore, we demonstrate that the physical meaning of the retrieved ALH scalar corresponds to the weighted average of the vertical aerosol extinction profile. These encouraging findings strongly suggest the potential of the OMI ALH product, and in more general the use of the 477 nm O2 − O2 band from present and future similar satellite sensors, for climate studies as well as for future aerosol correction in air quality trace gas retrievals.

  5. Molecular composition and seasonal variation of amino acids in urban aerosols from Beijing, China

    Science.gov (United States)

    Ren, Lujie; Bai, Huahua; Yu, Xi; Wu, Fengchang; Yue, Siyao; Ren, Hong; Li, Linjie; Lai, Senchao; Sun, Yele; Wang, Zifa; Fu, Pingqing

    2018-05-01

    Fifteen hydrolyzed amino acids (THAA) were quantified in urban aerosols (TSP samples) collected during April 2012 to May 2013 in Beijing, China using high-performance liquid chromatography (HPLC) after their derivatization with o-phthalaldehyde (OPA), to investigate their molecular distributions and seasonal variation. Total concentrations of amino acids ranged from 1.73-25.7 nmol m- 3 with a peak in spring (13.7 nmol m- 3), followed by winter (11.5 nmol m- 3), fall (9.51 nmol m- 3) and summer (7.45 nmol m- 3). Glycine (Gly), alanine (Ala) and valine (Val) are found to be the most abundant species, which account for 46% of the total THAA. Compared with those recorded in previous studies, the atmospheric levels of amino acids in Beijing were higher than those from other regions. Enhanced amounts of methionine, tyrosine, histidine, aspartic acid and glutamic acid were found during the rainfall events. The factor analysis further suggests that amino acids in urban Beijing originated from multiple sources including biological emission, biomass burning, as well as anthropogenic activities.

  6. Aerosol-cloud interactions from urban, regional to global scales

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuan [California Institute of Technology, Pasadena, CA (United States). Seismological Lab.

    2015-10-01

    The studies in this dissertation aim at advancing our scientific understandings about physical processes involved in the aerosol-cloud-precipitation interaction and quantitatively assessing the impacts of aerosols on the cloud systems with diverse scales over the globe on the basis of the observational data analysis and various modeling studies. As recognized in the Fifth Assessment Report by the Inter-government Panel on Climate Change, the magnitude of radiative forcing by atmospheric aerosols is highly uncertain, representing the largest uncertainty in projections of future climate by anthropogenic activities. By using a newly implemented cloud microphysical scheme in the cloud-resolving model, the thesis assesses aerosol-cloud interaction for distinct weather systems, ranging from individual cumulus to mesoscale convective systems. This thesis also introduces a novel hierarchical modeling approach that solves a long outstanding mismatch between simulations by regional weather models and global climate models in the climate modeling community. More importantly, the thesis provides key scientific solutions to several challenging questions in climate science, including the global impacts of the Asian pollution. As scientists wrestle with the complexities of climate change in response to varied anthropogenic forcing, perhaps no problem is more challenging than the understanding of the impacts of atmospheric aerosols from air pollution on clouds and the global circulation.

  7. Aerosol-cloud interactions from urban, regional to global scales

    International Nuclear Information System (INIS)

    Wang, Yuan

    2015-01-01

    The studies in this dissertation aim at advancing our scientific understandings about physical processes involved in the aerosol-cloud-precipitation interaction and quantitatively assessing the impacts of aerosols on the cloud systems with diverse scales over the globe on the basis of the observational data analysis and various modeling studies. As recognized in the Fifth Assessment Report by the Inter-government Panel on Climate Change, the magnitude of radiative forcing by atmospheric aerosols is highly uncertain, representing the largest uncertainty in projections of future climate by anthropogenic activities. By using a newly implemented cloud microphysical scheme in the cloud-resolving model, the thesis assesses aerosol-cloud interaction for distinct weather systems, ranging from individual cumulus to mesoscale convective systems. This thesis also introduces a novel hierarchical modeling approach that solves a long outstanding mismatch between simulations by regional weather models and global climate models in the climate modeling community. More importantly, the thesis provides key scientific solutions to several challenging questions in climate science, including the global impacts of the Asian pollution. As scientists wrestle with the complexities of climate change in response to varied anthropogenic forcing, perhaps no problem is more challenging than the understanding of the impacts of atmospheric aerosols from air pollution on clouds and the global circulation.

  8. Trace elements in the urban aerosol of Sao Paulo

    International Nuclear Information System (INIS)

    Orsini, C.M.Q.; Artaxo Netto, P.E.; Tabacniks, M.H.

    1983-07-01

    The first trace-element data-set measured on the atmosphere aerosol of Sao Paulo City, Brazil, is presented. These measurements have been based on samplings by 6-stage cascade impactors combined with the analytical procedure by the PIXE method of elementary analysis. (L.C.) [pt

  9. A single-column particle-resolved model for simulating the vertical distribution of aerosol mixing state: WRF-PartMC-MOSAIC-SCM v1.0

    Science.gov (United States)

    Curtis, Jeffrey H.; Riemer, Nicole; West, Matthew

    2017-11-01

    The PartMC-MOSAIC particle-resolved aerosol model was previously developed to predict the aerosol mixing state as it evolves in the atmosphere. However, the modeling framework was limited to a zero-dimensional box model approach without resolving spatial gradients in aerosol concentrations. This paper presents the development of stochastic particle methods to simulate turbulent diffusion and dry deposition of aerosol particles in a vertical column within the planetary boundary layer. The new model, WRF-PartMC-MOSAIC-SCM, resolves the vertical distribution of aerosol mixing state. We verified the new algorithms with analytical solutions for idealized test cases and illustrate the capabilities with results from a 2-day urban scenario that shows the evolution of black carbon mixing state in a vertical column.

  10. Real-Time Characterization of Aerosol Particle Composition above the Urban Canopy in Beijing: Insights into the Interactions between the Atmospheric Boundary Layer and Aerosol Chemistry.

    Science.gov (United States)

    Sun, Yele; Du, Wei; Wang, Qingqing; Zhang, Qi; Chen, Chen; Chen, Yong; Chen, Zhenyi; Fu, Pingqing; Wang, Zifa; Gao, Zhiqiu; Worsnop, Douglas R

    2015-10-06

    Despite extensive efforts into the characterization of air pollution during the past decade, real-time characterization of aerosol particle composition above the urban canopy in the megacity Beijing has never been performed to date. Here we conducted the first simultaneous real-time measurements of aerosol composition at two different heights at the same location in urban Beijing from December 19, 2013 to January 2, 2014. The nonrefractory submicron aerosol (NR-PM1) species were measured in situ by a high-resolution aerosol mass spectrometer at near-ground level and an aerosol chemical speciation monitor at 260 m on a 325 m meteorological tower in Beijing. Secondary aerosol showed similar temporal variations between ground level and 260 m, whereas much weaker correlations were found for the primary aerosol. The diurnal evolution of the ratios and correlations of aerosol species between 260 m and the ground level further illustrated a complex interaction between vertical mixing processes and local source emissions on aerosol chemistry in the atmospheric boundary layer. As a result, the aerosol compositions at the two heights were substantially different. Organic aerosol (OA), mainly composed of primary OA (62%), at the ground level showed a higher contribution to NR-PM1 (65%) than at 260 m (54%), whereas a higher concentration and contribution (15%) of nitrate was observed at 260 m, probably due to the favorable gas-particle partitioning under lower temperature conditions. In addition, two different boundary layer structures were observed, each interacting differently with the evolution processes of aerosol chemistry.

  11. Fine and coarse elemental components in the urban aerosol of Sao Paulo, Brazil

    International Nuclear Information System (INIS)

    Boueres, L.C.S.; Orsini, C.M.Q.

    1981-01-01

    Using cascade impactor sampling and PIXE analysis we have measured particle size distributions for approximately 15 elements in the Sao Paulo urban atmosphere. These elements, in our case, may be classified, according to their occurrence in fine or coarse aerosol log-normal modes, into three groups: (a) soil dust reference elements (coarse particle mode): Ti, Si and Ca; (b) anthropogenic fine particle mode: Zn, Br and Pb; and (c) mixed bimodal elements: S, K, V, Cr, Mn, Ni, Cu and Fe. All of the soil dust reference elements show consistently the log-normal parameters MMAD approx. 5.5 μm and sigmasub(g) approx. 3.2 (mass median aerodynamic diameter and geometric standard deviation, respectively). Enrichment factor calculations for Ti, Si, Ca and K in the coarse particle fraction (> 2 μmad), relative to Fe and the standard crustal aerosol values of Lawson and Winchester, show that Ti and Si are mainly soil derived while Ca and K may have significant industrial components in this particle fraction (i.e. coarse mode). The fine mode parameters for the other elements show variations with element suggesting different air pollution sources (such as motor vehicles, resuspended dust, refuse burning, industrial activities, etc.) and/or different chemical pathways, which presumably could be identifiable. For example, the modal parameters for group (b) are: Zn, MMAD = 0.9 μm, sigmasub(g) = 2.2; Br, MMAD = 0.5 μm, sigmasub(g) = 4.0; Pb, MMAD = 0.6 μm, sigmasub(g) = 3.0; thus suggesting a common source (automotive) for Br and Pb, unrelated to the source of Zn (possibly refuse burning). (orig.)

  12. Measurement of the ambient organic aerosol volatility distribution: application during the Finokalia Aerosol Measurement Experiment (FAME-2008

    Directory of Open Access Journals (Sweden)

    B. H. Lee

    2010-12-01

    Full Text Available A variable residence time thermodenuder (TD was combined with an Aerodyne Aerosol Mass Spectrometer (AMS and a Scanning Mobility Particle Sizer (SMPS to measure the volatility distribution of aged organic aerosol in the Eastern Mediterranean during the Finokalia Aerosol Measurement Experiment in May of 2008 (FAME-2008. A new method for the quantification of the organic aerosol volatility distribution was developed combining measurements of all three instruments together with an aerosol dynamics model.

    Challenges in the interpretation of ambient thermodenuder-AMS measurements include the potential resistances to mass transfer during particle evaporation, the effects of particle size on the evaporated mass fraction, the changes in the AMS collection efficiency and particle density as the particles evaporate partially in the TD, and finally potential losses inside the TD. Our proposed measurement and data analysis method accounts for all of these problems combining the AMS and SMPS measurements.

    The AMS collection efficiency of the aerosol that passed through the TD was found to be approximately 10% lower than the collection efficiency of the aerosol that passed through the bypass. The organic aerosol measured at Finokalia is approximately 2 or more orders of magnitude less volatile than fresh laboratory-generated monoterpene (α-pinene, β-pinene and limonene under low NOx conditions secondary organic aerosol. This low volatility is consistent with its highly oxygenated AMS mass spectrum. The results are found to be highly sensitive to the mass accommodation coefficient of the evaporating species. This analysis is based on the assumption that there were no significant reactions taking place inside the thermodenuder.

  13. Vertical distribution of aerosol optical properties in the Po Valley during the 2012 summer campaigns

    Directory of Open Access Journals (Sweden)

    S. Bucci

    2018-04-01

    Full Text Available Studying the vertical distribution of aerosol particle physical and chemical properties in the troposphere is essential to understand the relative importance of local emission processes vs. long-range transport for column-integrated aerosol properties (e.g. the aerosol optical depth, AOD, affecting regional climate as well as for the aerosol burden and its impacts on air quality at the ground. The main objective of this paper is to investigate the transport of desert dust in the middle troposphere and its intrusion into the planetary boundary layer (PBL over the Po Valley (Italy, a region considered one of the greatest European pollution hotspots for the frequency that particulate matter (PM limit values are exceeded. Events of mineral aerosol uplift from local (soil sources and phenomena of hygroscopic growth at the ground are also investigated, possibly affecting the PM concentration in the region as well. During the PEGASOS 2012 field campaign, an integrated observing–modelling system was set up based on near-surface measurements (particle concentration and chemistry, vertical profiling (backscatter coefficient profiles from lidar and radiosoundings and Lagrangian air mass transport simulations by FLEXPART model. Measurements were taken at the San Pietro Capofiume supersite (44°39′ N, 11°37′ E; 11 m a.s.l., located in a rural area relatively close to some major urban and industrial emissive areas in the Po Valley. Mt. Cimone (44°12′ N, 10°42′ E; 2165 m a.s.l. WMO/GAW station observations are also included in the study to characterize regional-scale variability. Results show that, in the Po Valley, aerosol is detected mainly below 2000 m a.s.l. with a prevalent occurrence of non-depolarizing particles ( > 50 % throughout the campaign and a vertical distribution modulated by the PBL daily evolution. Two intense events of mineral dust transport from northern Africa (19–21 and 29 June to 2 July are

  14. Vertical distribution of aerosol optical properties in the Po Valley during the 2012 summer campaigns

    Science.gov (United States)

    Bucci, Silvia; Cristofanelli, Paolo; Decesari, Stefano; Marinoni, Angela; Sandrini, Silvia; Größ, Johannes; Wiedensohler, Alfred; Di Marco, Chiara F.; Nemitz, Eiko; Cairo, Francesco; Di Liberto, Luca; Fierli, Federico

    2018-04-01

    Studying the vertical distribution of aerosol particle physical and chemical properties in the troposphere is essential to understand the relative importance of local emission processes vs. long-range transport for column-integrated aerosol properties (e.g. the aerosol optical depth, AOD, affecting regional climate) as well as for the aerosol burden and its impacts on air quality at the ground. The main objective of this paper is to investigate the transport of desert dust in the middle troposphere and its intrusion into the planetary boundary layer (PBL) over the Po Valley (Italy), a region considered one of the greatest European pollution hotspots for the frequency that particulate matter (PM) limit values are exceeded. Events of mineral aerosol uplift from local (soil) sources and phenomena of hygroscopic growth at the ground are also investigated, possibly affecting the PM concentration in the region as well. During the PEGASOS 2012 field campaign, an integrated observing-modelling system was set up based on near-surface measurements (particle concentration and chemistry), vertical profiling (backscatter coefficient profiles from lidar and radiosoundings) and Lagrangian air mass transport simulations by FLEXPART model. Measurements were taken at the San Pietro Capofiume supersite (44°39' N, 11°37' E; 11 m a.s.l.), located in a rural area relatively close to some major urban and industrial emissive areas in the Po Valley. Mt. Cimone (44°12' N, 10°42' E; 2165 m a.s.l.) WMO/GAW station observations are also included in the study to characterize regional-scale variability. Results show that, in the Po Valley, aerosol is detected mainly below 2000 m a.s.l. with a prevalent occurrence of non-depolarizing particles ( > 50 % throughout the campaign) and a vertical distribution modulated by the PBL daily evolution. Two intense events of mineral dust transport from northern Africa (19-21 and 29 June to 2 July) are observed, with layers advected mainly above 2000 m

  15. Aircraft observations of aerosols O3 and NOy in a nighttime urban plume

    International Nuclear Information System (INIS)

    Berkowitz, C.M.; Zaveri, R.A.; Xindi Bian; Shiyuan Zhong; Disselkamp, R.S.; Laulainen, N.S.; Chapman, E.G.

    2001-01-01

    Nighttime measurements of aerosol surface area, O 3 , NO y and moisture were made downwind of Portland, Oregon, as part of a study to characterize the chemistry in a nocturnal urban plume. Air parcels sampled within the urban plume soon after sunset had positive correlations between O 3 , relative humidity, NO y and aerosol number density. However, the air parcels sampled within the urban plume just before dawn had O 3 mixing ratios that were highly anti-correlated with aerosol number density, NO y and relative humidity. Back-trajectories from a mesoscale model show that both the post-sunset and pre-dawn parcels came from a common maritime source to the northwest of Portland. The pre-dawn parcels with strong anti-correlations passed directly over Portland in contrast to the other parcels that were found to pass west of Portland. Several gas-phase mechanisms and a heterogeneous mechanism involving the loss of O 3 to the aerosol surface, are examined to explain the observed depletion in O 3 within the pre-dawn parcels that had passed over Portland. (Author)

  16. Receptor modelling of atmospheric aerosols in the urban area of Sao Paulo. Appendix 5

    International Nuclear Information System (INIS)

    Artaxo, P.; Castro, W.E. Jr. de; Freitas, M. de; Longo, K.M.

    1995-01-01

    The urban area of Sao Paulo has shown high concentrations of inhalable particulate matter, indicating air pollution problems. Back carbon concentration represents 26.1±9.7% of the fine mode aerosol mass, indicating the importance of diesel emission. Factor analysis was able to separate four factors, with a transportation-related component, a resuspended soil dust and an oil combustion component. A fourth factor mainly with Br was also observed. An independent multivariate analysis technique using Cluster analysis showed very similar elemental relationships. The results indicate that the transportation sector gives an important contribution to fine mode aerosol concentration

  17. Receptor modelling of atmospheric aerosols in the urban area of Sao Paulo. Appendix 5

    Energy Technology Data Exchange (ETDEWEB)

    Artaxo, P; Castro, W.E. Jr. de; Freitas, M de; Longo, K M [Grupo de Estudos de Poluicao do Ar, Departamento de Fisica Aplicada, Instituto de Fisica, Universidade de Sao Paulo, USP, Sao Paulo, SP (Brazil)

    1995-07-01

    The urban area of Sao Paulo has shown high concentrations of inhalable particulate matter, indicating air pollution problems. Back carbon concentration represents 26.1{+-}9.7% of the fine mode aerosol mass, indicating the importance of diesel emission. Factor analysis was able to separate four factors, with a transportation-related component, a resuspended soil dust and an oil combustion component. A fourth factor mainly with Br was also observed. An independent multivariate analysis technique using Cluster analysis showed very similar elemental relationships. The results indicate that the transportation sector gives an important contribution to fine mode aerosol concentration.

  18. Simultaneous PIXE and PIGE analyses of aerosol samples collected in urban areas

    International Nuclear Information System (INIS)

    Boni, C.; Caruso, E.; Cereda, E.; Marcazzan, G.M.; Redaelli, P.; Bacci, P.

    1988-01-01

    The paper concerns the simultaneous PIXE (Particle Induced X-ray Emission) and PIGE (Proton Induced Gamma-ray Emission) analyses of aerosol samples collected in urban areas. The results show that PIGE can detect Li, F, Na, Al, and Si in fly ashes and F, Na, Al and Si in atmospheric aerosol. The PIXE-PIGE technique has also been applied to 80 samples of atmospheric particular matter collected above Milan during the winter and summer months of 1986/7, and the average values of concentrations and enrichment factors are given for the detected elements. (U.K.)

  19. Atmospheric aerosol in an urban area: Comparison of measurement instruments and methodologies and pulmonary deposition assessment; Aerosol atmosferico in area urbanae di misura e valutazione di deposizione polmonare

    Energy Technology Data Exchange (ETDEWEB)

    Berico, M; Luciani, A; Formignani, M [ENEA, Centro Ricerche Bologna (Italy). Dip. Ambiente

    1996-07-01

    In March 1995 a measurement campaign of atmospheric aerosol in the Bologna urban area (Italy) was carried out. A transportable laboratory, set up by ENEA (Italian national Agency for New Technologies, Energy and the Environment) Environmental Department (Bologna), was utilized with instruments for measurement of atmospheric aerosol and meteorological parameters. The aim of this campaign was of dual purpose: to characterize aerosol in urban area and to compare different instruments and methodologies of measurements. Mass concentrations measurements, evaluated on a 23-hour period with total filter, PM10 dichotomous sampler and low pressure impactor (LPI Berner), have provided information respectively about total suspended particles, respirable fraction and granulometric parameters of aerosol. Eight meteorologic parameters, number concentration of submicromic fraction of aerosol and mass concentration of micromic fraction have been continually measured. Then, in a daytime period, several number granulometries of atmospheric aerosol have also been estimated by means of diffusion battery system. Results related to different measurement methodologies and granulometric characteristics of aerosol are presented here. Pulmonary deposition of atmospheric aerosol is finally calculated, using granulometries provided by LPI Brener and ICRP 66 human respiratory tract model.

  20. A model study of the size and composition distribution of aerosols in an aircraft exhaust

    Energy Technology Data Exchange (ETDEWEB)

    Sorokin, A.A. [SRC `ECOLEN`, Moscow (Russian Federation)

    1997-12-31

    A two-dimensional, axisymmetric flow field model which includes water and sulphate aerosol formation represented by moments of the size and composition distribution function is used to calculate the effect of radial turbulent jet mixing on the aerosol size distribution and mean modal composition. (author) 6 refs.

  1. A model study of the size and composition distribution of aerosols in an aircraft exhaust

    Energy Technology Data Exchange (ETDEWEB)

    Sorokin, A A [SRC ` ECOLEN` , Moscow (Russian Federation)

    1998-12-31

    A two-dimensional, axisymmetric flow field model which includes water and sulphate aerosol formation represented by moments of the size and composition distribution function is used to calculate the effect of radial turbulent jet mixing on the aerosol size distribution and mean modal composition. (author) 6 refs.

  2. Urban air quality assessment using monitoring data of fractionized aerosol samples, chemometrics and meteorological conditions.

    Science.gov (United States)

    Yotova, Galina I; Tsitouridou, Roxani; Tsakovski, Stefan L; Simeonov, Vasil D

    2016-01-01

    The present article deals with assessment of urban air by using monitoring data for 10 different aerosol fractions (0.015-16 μm) collected at a typical urban site in City of Thessaloniki, Greece. The data set was subject to multivariate statistical analysis (cluster analysis and principal components analysis) and, additionally, to HYSPLIT back trajectory modeling in order to assess in a better way the impact of the weather conditions on the pollution sources identified. A specific element of the study is the effort to clarify the role of outliers in the data set. The reason for the appearance of outliers is strongly related to the atmospheric condition on the particular sampling days leading to enhanced concentration of pollutants (secondary emissions, sea sprays, road and soil dust, combustion processes) especially for ultra fine and coarse particles. It is also shown that three major sources affect the urban air quality of the location studied-sea sprays, mineral dust and anthropogenic influences (agricultural activity, combustion processes, and industrial sources). The level of impact is related to certain extent to the aerosol fraction size. The assessment of the meteorological conditions leads to defining of four downwind patterns affecting the air quality (Pelagic, Western and Central Europe, Eastern and Northeastern Europe and Africa and Southern Europe). Thus, the present study offers a complete urban air assessment taking into account the weather conditions, pollution sources and aerosol fractioning.

  3. Identification of the sources of primary organic aerosols at urban schools: A molecular marker approach

    International Nuclear Information System (INIS)

    Crilley, Leigh R.; Qadir, Raeed M.; Ayoko, Godwin A.; Schnelle-Kreis, Jürgen; Abbaszade, Gülcin; Orasche, Jürgen; Zimmermann, Ralf; Morawska, Lidia

    2014-01-01

    Children are particularly susceptible to air pollution and schools are examples of urban microenvironments that can account for a large portion of children's exposure to airborne particles. Thus this paper aimed to determine the sources of primary airborne particles that children are exposed to at school by analyzing selected organic molecular markers at 11 urban schools in Brisbane, Australia. Positive matrix factorization analysis identified four sources at the schools: vehicle emissions, biomass burning, meat cooking and plant wax emissions accounting for 45%, 29%, 16% and 7%, of the organic carbon respectively. Biomass burning peaked in winter due to prescribed burning of bushland around Brisbane. Overall, the results indicated that both local (traffic) and regional (biomass burning) sources of primary organic aerosols influence the levels of ambient particles that children are exposed at the schools. These results have implications for potential control strategies for mitigating exposure at schools. - Highlights: • Selected organic molecular markers at 11 urban schools were analyzed. • Four sources of primary organic aerosols were identified by PMF at the schools. • Both local and regional sources were found to influence exposure at the schools. • The results have implications for mitigation of children's exposure at schools. - The identification of the most important sources of primary organic aerosols at urban schools has implications for control strategies for mitigating children's exposure at schools

  4. Dust aerosol properties and radiative forcing observed in spring during 2001-2014 over urban Beijing, China.

    Science.gov (United States)

    Yu, Xingna; Lü, Rui; Kumar, K Raghavendra; Ma, Jia; Zhang, Qiuju; Jiang, Yilun; Kang, Na; Yang, Suying; Wang, Jing; Li, Mei

    2016-08-01

    The ground-based characteristics (optical and radiative properties) of dust aerosols measured during the springtime between 2001 and 2014 were investigated over urban Beijing, China. The seasonal averaged aerosol optical depth (AOD) during spring of 2001-2014 was about 0.78 at 440 nm. During dust days, higher AOD occurred associated with lower Ångström exponent (AE). The mean AE440-870 in the springtime was about 1.0, indicating dominance of fine particles over the region. The back-trajectory analysis revealed that the dust was transported from the deserts of Inner Mongolia and Mongolia arid regions to Beijing. The aerosol volume size distribution showed a bimodal distribution pattern, with its highest peak observed in coarse mode for all episodes (especially for dust days with increased volume concentration). The single scattering albedo (SSA) increased with wavelength on dust days, indicating the presence of more scattering particles. Furthermore, the complex parts (real and imaginary) of refractive index showed distinct characteristics with lower imaginary values (also scattering) on dust days. The shortwave (SW; 0.2-4.0 μm) and longwave (LW; 4-100 μm) aerosol radiative forcing (ARF) values were computed from the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model both at the top of atmosphere (TOA) and the bottom of atmosphere (BOA) during dust and non-dust (dust free) days, and the corresponding heating rates and forcing efficiencies were also estimated. The SW (LW) ARF, therefore, produced significant cooling (warming) effects at both the TOA and the BOA over Beijing.

  5. Distributed intelligent urban environment monitoring system

    Science.gov (United States)

    Du, Jinsong; Wang, Wei; Gao, Jie; Cong, Rigang

    2018-02-01

    The current environmental pollution and destruction have developed into a world-wide major social problem that threatens human survival and development. Environmental monitoring is the prerequisite and basis of environmental governance, but overall, the current environmental monitoring system is facing a series of problems. Based on the electrochemical sensor, this paper designs a small, low-cost, easy to layout urban environmental quality monitoring terminal, and multi-terminal constitutes a distributed network. The system has been small-scale demonstration applications and has confirmed that the system is suitable for large-scale promotion

  6. Primary organic pollutants in New Zealand urban aerosol in winter during high PM1 episodes

    International Nuclear Information System (INIS)

    Krivacsy, Zoltan; Blazso, Marianne; Shooter, David

    2006-01-01

    In the two biggest New Zealand cities, Auckland and Christchurch, the mass concentration of the PM 1 atmospheric aerosol can exceed the 50 μg m -3 24 h health guideline in winter. This high pollution level is thought to be caused mainly by old-fashioned domestic heating systems based on wood combustion. Therefore the chemistry of the carbonaceous aerosol has been investigated in several high-pollution level urban situations in order to assess the origin of the pollution. All the high concentration organic tracers, including levoglucosan and dehydroabietic acid, were characteristic for biomass burning. The findings have confirmed via advanced chemical analytical methods that domestic heating can be the main contributor to the high level of wintertime pollution, especially in Christchurch. The results are of great importance in supporting the ambition of authorities and environmental associations to change the domestic heating regimes. - PM 1 aerosol concentrations can exceed air quality guidelines during winter in Christchurch, New Zealand

  7. Highly time-resolved urban aerosol characteristics during springtime in Yangtze River Delta, China: insights from soot particle aerosol mass spectrometry

    Science.gov (United States)

    Wang, Junfeng; Ge, Xinlei; Chen, Yanfang; Shen, Yafei; Zhang, Qi; Sun, Yele; Xu, Jianzhong; Ge, Shun; Yu, Huan; Chen, Mindong

    2016-07-01

    In this work, the Aerodyne soot particle - aerosol mass spectrometer (SP-AMS) was deployed for the first time during the spring of 2015 in urban Nanjing, a megacity in the Yangtze River Delta (YRD) of China, for online characterization of the submicron aerosols (PM1). The SP-AMS enables real-time and fast quantification of refractory black carbon (rBC) simultaneously with other non-refractory species (ammonium, sulfate, nitrate, chloride, and organics). The average PM1 concentration was found to be 28.2 µg m-3, with organics (45 %) as the most abundant component, following by sulfate (19.3 %), nitrate (13.6 %), ammonium (11.1 %), rBC (9.7 %), and chloride (1.3 %). These PM1 species together can reconstruct ˜ 44 % of the light extinction during this campaign based on the IMPROVE method. Chemically resolved mass-based size distributions revealed that small particles especially ultrafine ones (cooking-related OA (COA), semi-volatile oxygenated OA (SV-OOA), and low-volatility oxygenated OA (LV-OOA). Overall, secondary organic aerosol (SOA, equal to the sum of SV-OOA and LV-OOA) dominated the total OA mass (55.5 %), but primary organic aerosol (POA, equal to the sum of HOA and COA) can outweigh SOA in the early morning and evening due to enhanced human activities. High OA concentrations were often associated with high mass fractions of POA and rBC, indicating the important role of anthropogenic emissions during heavy pollution events. The diurnal cycles of nitrate, chloride, and SV-OOA both showed good anti-correlations with air temperatures, suggesting their variations were likely driven by thermodynamic equilibria and gas-to-particle partitioning. On the other hand, in contrast to other species, sulfate, and LV-OOA concentrations increased in the afternoon, and showed no positive correlations with relative humidity (RH), likely indicating the contribution from photochemical oxidation is dominant over that of aqueous-phase processing for their formations. The

  8. Particle size distributions of radioactive aerosols measured in workplaces

    International Nuclear Information System (INIS)

    Dorrian, M.-D.; Bailey, M.R.

    1995-01-01

    A survey of published values of Activity Median Aerodynamic Diameter (AMAD) measured in working environments was conducted to assist in the selection of a realistic default AMAD for occupational exposures. Results were compiled from 52 publications covering a wide variety of industries and workplaces. Reported values of AMAD from all studies ranged from 0.12 μm to 25 μm, and most were well fitted by a log-normal distribution with a median value of 4.4 μm. This supports the choice of a 5 μm default AMAD, as a realistic rounded value for occupational exposures, by the ICRP Task Group on Human Respiratory Tract Models for Radiological Protection and its acceptance by ICRP. Both the nuclear power and nuclear fuel handling industries gave median values of approximately 4 μm. Uranium mills gave a median value of 6.8 μm with AMADs frequently greater than 10 μm. High temperature and arc saw cutting operations generated submicron particles and occasionally, biomodal log-normal particle size distributions. It is concluded that in view of the wide range of AMADs found in the surveyed literature, greater emphasis should be placed on air sampling to characterise aerosol particle size distributions for individual work practices, especially as doses estimated with the new 5 μm default AMAD will not always be conservative. (author)

  9. Influence of extreme events on health-related aerosol particle deposition in an urban site during summer

    Science.gov (United States)

    Belmonte, Paula; Castro, Amaya; Calvo, Ana Isabel; Alves, Célia; Duarte, Márcio; Alonso-Blanco, Elisabeth; Fraile, Roberto

    2014-05-01

    Urban populations are exposed to aerosol particles that enter in the human respiratory track posing an important risk to human health. Particle sampling conventions have been established, expressed as curves describing "penetration" to the region of interest in terms of the particle aerodynamic diameter. The inhalable, thoracic, traqueo-bronchial and respirable fractions have been estimated according to the International Standard ISO 7708:1995. This study presents the analysis of aerosol size distributions and its deposition in the human respiratory tract according to ISO 7708. The influence of ambient conditions in an urban area affected by heat waves and wildfires in the summer months has been analyzed. A laser spectrometer PCASP-X was used to characterize the aerosol size distributions. This device registers particle sizes between 0.1 and 10 microns in 31 channels. The spectrometer was installed in the city of León (Spain), between June and September 2012, and 24 measurements were carried out daily to determine the size of the ambient particles in the urban area. The measurements were averaged over 15-minute intervals. A weather station was installed at 3 m above the ground to register automatically data on precipitation, pressure, temperature, relative humidity wind speed and direction. The refractive index of the particles was estimated for each value of relative humidity, as the relative humidity of the ambient atmosphere affects the size and the complex refractive index of aerosols. Afterwards, raw size bins were corrected from the estimated refractive indices using a program based on Mie Theory. The regional government provided data on the exact location of summer wildfires in the province of Leon, as well as data on the land area affected. A persistent and intense thermal inversion of subsidence caused an intense pollution episode in the city during the main wildfire, which broke out at a distance of about 60 km from the sampling point. Furthermore, the

  10. Aerosol vertical distribution characteristics over the Tibetan Plateau

    International Nuclear Information System (INIS)

    Deng, Z Q; Han, Y X; Zhao, Q; Li, J

    2014-01-01

    The Stratospheric Aerosol and Gas Experiment II (SAGE II) aerosol products are widely used in climatic characteristic studies and stratospheric aerosol pattern research. Some SAGE II products, e.g., temperature, aerosol surface area density, 1020 nm aerosol extinction coefficient and dust storm frequency, from ground-based observations were analysed from 1984 to 2005. This analysis explored the time and spatial variations of tropospheric and stratospheric aerosols on the Tibet Plateau. The stratospheric aerosol extinction coefficient increased more than two orders of magnitude because of a large volcanic eruption. However, the tropospheric aerosol extinction coefficient decreased over the same period. Removing the volcanic eruption effect, the correlation coefficient for stratospheric AOD (Aerosol Optical Depth) and tropospheric AOD was 0.197. Moreover, the correlation coefficient for stratospheric AOD and dust storm frequency was 0.315. The maximum stratospheric AOD was attained in January, the same month as the tropospheric AOD, when the Qaidam Basin was the centre of low tropospheric AOD and the large mountains coincided with high stratospheric AOD. The vertical structure generated by westerly jet adjustment and the high altitude of the underlying surface of the Tibetan Plateau were important factors affecting winter stratospheric aerosols

  11. Lidar measurements of ozone and aerosol distributions during the 1992 airborne Arctic stratospheric expedition

    Science.gov (United States)

    Browell, Edward V.; Butler, Carolyn F.; Fenn, Marta A.; Grant, William B.; Ismail, Syed; Carter, Arlen F.

    1994-01-01

    The NASA Langley airborne differential absorption lidar system was operated from the NASA Ames DC-8 aircraft during the 1992 Airborne Arctic Stratospheric Expedition to investigate the distribution of stratospheric aerosols and ozone (O3) across the Arctic vortex from January to March 1992. Aerosols from the Mt. Pinatubo eruption were found outside and inside the Arctic vortex with distinctly different scattering characteristics and spatial distributions in the two regions. The aerosol and O3 distributions clearly identified the edge of the vortex and provided additional information on vortex dynamics and transport processes. Few polar stratospheric clouds were observed during the AASE-2; however, those that were found had enhanced scattering and depolarization over the background Pinatubo aerosols. The distribution of aerosols inside the vortex exhibited relatively minor changes during the AASE-2. Ozone depletion inside the vortex as limited to less than or equal to 20 percent in the altitude region from 15-20 km.

  12. Isotopic evidence for enhanced fossil fuel sources of aerosol ammonium in the urban atmosphere.

    Science.gov (United States)

    Pan, Yuepeng; Tian, Shili; Liu, Dongwei; Fang, Yunting; Zhu, Xiaying; Gao, Meng; Gao, Jian; Michalski, Greg; Wang, Yuesi

    2018-04-20

    The sources of aerosol ammonium (NH 4 + ) are of interest because of the potential of NH 4 + to impact the Earth's radiative balance, as well as human health and biological diversity. Isotopic source apportionment of aerosol NH 4 + is challenging in the urban atmosphere, which has excess ammonia (NH 3 ) and where nitrogen isotopic fractionation commonly occurs. Based on year-round isotopic measurements in urban Beijing, we show the source dependence of the isotopic abundance of aerosol NH 4 + , with isotopically light (-33.8‰) and heavy (0 to +12.0‰) NH 4 + associated with strong northerly winds and sustained southerly winds, respectively. On an annual basis, 37-52% of the initial NH 3 concentrations in urban Beijing arises from fossil fuel emissions, which are episodically enhanced by air mass stagnation preceding the passage of cold fronts. These results provide strong evidence for the contribution of non-agricultural sources to NH 3 in urban regions and suggest that priority should be given to controlling these emissions for haze regulation. This study presents a carefully executed application of existing stable nitrogen isotope measurement and mass-balance techniques to a very important problem: understanding source contributions to atmospheric NH 3 in Beijing. This question is crucial to informing environmental policy on reducing particulate matter concentrations, which are some of the highest in the world. However, the isotopic source attribution results presented here still involve a number of uncertain assumptions and they are limited by the incomplete set of chemical and isotopic measurements of gas NH 3 and aerosol NH 4 + . Further field work and lab experiments are required to adequately characterize endmember isotopic signatures and the subsequent isotopic fractionation process under different air pollution and meteorological conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. A receptor model for urban aerosols based on oblique factor analysis

    DEFF Research Database (Denmark)

    Keiding, Kristian; Sørensen, Morten S.; Pind, Niels

    1987-01-01

    A procedure is outlined for the construction of receptor models of urban aerosols, based on factor analysis. The advantage of the procedure is that the covariation of source impacts is included in the construction of the models. The results are compared with results obtained by other receptor......-modelling procedures. It was found that procedures based on correlating sources were physically sound as well as in mutual agreement. Procedures based on non-correlating sources were found to generate physically obscure models....

  14. Nitrogen, Aerosol Composition, and Halogens on a Tall Tower (NACHTT): Overview of a wintertime air chemistry field study in the front range urban corridor of Colorado

    Science.gov (United States)

    Brown, Steven S.; Thornton, Joel A.; Keene, William C.; Pszenny, Alexander A. P.; Sive, Barkley C.; Dubé, William P.; Wagner, Nicholas L.; Young, Cora J.; Riedel, Theran P.; Roberts, James M.; VandenBoer, Trevor C.; Bahreini, Roya; Öztürk, Fatma; Middlebrook, Ann M.; Kim, Saewung; Hübler, Gerhard; Wolfe, Daniel E.

    2013-07-01

    The Nitrogen, Aerosol Composition, and Halogens on a Tall Tower (NACHTT) field experiment took place during late winter, 2011, at a site 33 km north of Denver, Colorado. The study included fixed-height measurements of aerosols, soluble trace gases, and volatile organic compounds near surface level, as well as vertically resolved measurements of nitrogen oxides, aerosol composition, soluble gas-phase acids, and halogen species from 3 to 270 m above ground level. There were 1928 individual profiles during the three-week campaign to characterize trace gas and aerosol distributions in the lower levels of the boundary layer. Nitrate and ammonium dominated the ionic composition of aerosols and originated primarily from local or regional sources. Sulfate and organic matter were also significant and were associated primarily with longer-range transport to the region. Aerosol chloride was associated primarily with supermicron size fractions and was always present in excess of gas-phase chlorine compounds. The nighttime radical reservoirs, nitryl chloride, ClNO2, and nitrous acid, HONO, were both consistently present in nighttime urban air. Nitryl chloride was especially pronounced in plumes from large point sources sampled aloft at night. Nitrous acid was typically most concentrated near the ground surface and was the dominant contributor (80%) to diurnally averaged primary OH radical production in near-surface air. Large observed mixing ratios of light alkanes, both in near-surface air and aloft, were attributable to local emissions from oil and gas activities.

  15. Study of particle size and trace metal distribution in atmospheric aerosols of islamabad

    International Nuclear Information System (INIS)

    Shah, M.H.; Shaheen, N.

    2009-01-01

    Atmospheric aerosol samples were collected on glass fibre filters using high volume air samplers Half of each aerosol sample was solubilized in nitric acid/hydrochloric acid based wet digestion method and the concentration of trace metals was determined through flame atomic absorption spectrophotometer. Among the eight trace metals analyzed, mean concentration recorded for Zn (844 ng/m3), Fe (642 ng/m3) and Pb (253 ng/m3), was found to be higher than mean levels of Mn, Cr and Co. The size distribution of the collected particulate samples was carried out on mastersizer, which revealed PM/sub 100-10/ as the major fraction (55 %) followed by PM/sub 2.5-10/ (28 %). The correlation study evidenced a strong tendency of trace metals to be associated with fine particulate fractions. The atmospheric trace metal levels showed that the mean metal concentrations in the atmosphere of Islamabad are far higher than background and European urban sites mainly due to the anthropogenic emissions. (author)

  16. Density and radioactivity distribution of respirable range human serum albumin aerosol

    International Nuclear Information System (INIS)

    Raghunath, B.; Somasundaram, S.; Soni, P.S.

    1988-01-01

    Dry human serum albumin (HSA) aerosol in the respirable size range was generated using the BARC nebulizer. The aerosol was sampled using Lovelace Aerosol Particle Separator (LAPS) and the density of HSA was determined. Labelling of HSA with 99m TcO 4 - was done, both in HSA solution and with dry denatured HSA particles, to study the distribution of radioactivity in both cases. The results are discussed. (author)

  17. Geophysical applicability of aerosol size distribution measurements using cascade impactors and proton induced X-ray emission

    International Nuclear Information System (INIS)

    Van Grieken, R.E.; Johansson, T.B.; Akselsson, K.R.; Winchester, J.W.; Nelson, J.W.; Chapman, K.R.

    1976-01-01

    Proton Induced X-ray Emission, (PIXE), is capable of high precision analysis for trace element components of aerosol particle size fractions sampled by cascade impactor. A statistical evaluation of data quality has been carried out in order to distinguish between analytical uncertainties in the PIXE procedure, errors caused by cascade impactor performance and by other factors in the sampling procedure, and geophysical causes of differences in composition and particle size distributions of the elements in aerosols. Replicate analyses and simultaneous samplings taken in north Florida and St. Louis have been used for the data evaluation. In addition to the analytical error the sampling procedure contributes an error of approximately 10% to be added quadratically. The resulting precision is sufficient to evaluate the data in geophysical terms. This is illustrated by means of sample sets taken simultaneously in an urban, forest and coastal environment of the same region. (author)

  18. Aerosol Optical Depth Distribution in Extratropical Cyclones over the Northern Hemisphere Oceans

    Science.gov (United States)

    Naud, Catherine M.; Posselt, Derek J.; van den Heever, Susan C.

    2016-01-01

    Using Moderate Resolution Imaging Spectroradiometer and an extratropical cyclone database,the climatological distribution of aerosol optical depth (AOD) in extratropical cyclones is explored based solely on observations. Cyclone-centered composites of aerosol optical depth are constructed for the Northern Hemisphere mid-latitude ocean regions, and their seasonal variations are examined. These composites are found to be qualitatively stable when the impact of clouds and surface insolation or brightness is tested. The larger AODs occur in spring and summer and are preferentially found in the warm frontal and in the post-cold frontal regions in all seasons. The fine mode aerosols dominate the cold sector AODs, but the coarse mode aerosols display large AODs in the warm sector. These differences between the aerosol modes are related to the varying source regions of the aerosols and could potentially have different impacts on cloud and precipitation within the cyclones.

  19. Volatility measurement of atmospheric submicron aerosols in an urban atmosphere in southern China

    Science.gov (United States)

    Cao, Li-Ming; Huang, Xiao-Feng; Li, Yuan-Yuan; Hu, Min; He, Ling-Yan

    2018-02-01

    Aerosol pollution has been a very serious environmental problem in China for many years. The volatility of aerosols can affect the distribution of compounds in the gas and aerosol phases, the atmospheric fates of the corresponding components, and the measurement of the concentration of aerosols. Compared to the characterization of chemical composition, few studies have focused on the volatility of aerosols in China. In this study, a thermodenuder aerosol mass spectrometer (TD-AMS) system was deployed to study the volatility of non-refractory submicron particulate matter (PM1) species during winter in Shenzhen. To our knowledge, this paper is the first report of the volatilities of aerosol chemical components based on a TD-AMS system in China. The average PM1 mass concentration during the experiment was 42.7±20.1 µg m-3, with organic aerosol (OA) being the most abundant component (43.2 % of the total mass). The volatility of chemical species measured by the AMS varied, with nitrate showing the highest volatility, with a mass fraction remaining (MFR) of 0.57 at 50 °C. Organics showed semi-volatile characteristics (the MFR was 0.88 at 50 °C), and the volatility had a relatively linear correlation with the TD temperature (from the ambient temperature to 200 °C), with an evaporation rate of 0.45 % °C-1. Five subtypes of OA were resolved from total OA using positive matrix factorization (PMF) for data obtained under both ambient temperature and high temperatures through the TD, including a hydrocarbon-like OA (HOA, accounting for 13.5 %), a cooking OA (COA, 20.6 %), a biomass-burning OA (BBOA, 8.9 %), and two oxygenated OAs (OOAs): a less-oxidized OOA (LO-OOA, 39.1 %) and a more-oxidized OOA (MO-OOA, 17.9 %). Different OA factors presented different volatilities, and the volatility sequence of the OA factors at 50 °C was HOA (MFR of 0.56) > LO-OOA (0.70) > COA (0.85) ≈ BBOA (0.87) > MO-OOA (0.99), which was not completely consistent with the sequence of their O

  20. Spatial and seasonal patterns in urban influence on regional concentrations of speciated aerosols across the United States

    Science.gov (United States)

    Hand, J. L.; Schichtel, B. A.; Malm, W. C.; Pitchford, M.; Frank, N. H.

    2014-11-01

    Monthly, seasonal, and annual mean estimates of urban influence on regional concentrations of major aerosol species were computed using speciated aerosol data from the rural IMPROVE network (Interagency Monitoring of Protected Visual Environments) and the United States Environmental Protection Agency's urban Chemical Speciation Network for the 2008 through 2011 period. Aggregated for sites across the continental United States, the annual mean and one standard error in urban excess (defined as the ratio of urban to nearby rural concentrations) was highest for elemental carbon (3.3 ± 0.2), followed by ammonium nitrate (2.5 ± 0.2), particulate organic matter (1.78 ± 0.08), and ammonium sulfate (1.23 ± 0.03). The seasonal variability in urban excess was significant for carbonaceous aerosols and ammonium nitrate in the West, in contrast to the low seasonal variability in the urban influence of ammonium sulfate. Generally for all species, higher excess values in the West were associated with localized urban sources while in the East excess was more regional in extent. In addition, higher excess values in the western United States in winter were likely influenced not only by differences in sources but also by combined meteorological and topographic effects. This work has implications for understanding the spatial heterogeneity of major aerosol species near the interface of urban and rural regions and therefore for designing appropriate air quality management strategies. In addition, the spatial patterns in speciated mass concentrations provide constraints for regional and global models.

  1. A new stochastic algorithm for inversion of dust aerosol size distribution

    Science.gov (United States)

    Wang, Li; Li, Feng; Yang, Ma-ying

    2015-08-01

    Dust aerosol size distribution is an important source of information about atmospheric aerosols, and it can be determined from multiwavelength extinction measurements. This paper describes a stochastic inverse technique based on artificial bee colony (ABC) algorithm to invert the dust aerosol size distribution by light extinction method. The direct problems for the size distribution of water drop and dust particle, which are the main elements of atmospheric aerosols, are solved by the Mie theory and the Lambert-Beer Law in multispectral region. And then, the parameters of three widely used functions, i.e. the log normal distribution (L-N), the Junge distribution (J-J), and the normal distribution (N-N), which can provide the most useful representation of aerosol size distributions, are inversed by the ABC algorithm in the dependent model. Numerical results show that the ABC algorithm can be successfully applied to recover the aerosol size distribution with high feasibility and reliability even in the presence of random noise.

  2. Modeling and measurements of urban aerosol processes on the neighborhood scale in Rotterdam, Oslo and Helsinki

    NARCIS (Netherlands)

    Karl, M.; Kukkonen, J.; Keuken, M.P.; Lützenkirchen, S.; Pirjola, L.; Hussein, T.

    2016-01-01

    This study evaluates the influence of aerosol processes on the particle number (PN) concentrations in three major European cities on the temporal scale of 1 h, i.e., on the neighborhood and city scales. We have used selected measured data of particle size distributions from previous campaigns in the

  3. Distributed models coupling soakaways, urban drainage and groundwater

    DEFF Research Database (Denmark)

    Roldin, Maria Kerstin

    in receiving waters, urban flooding etc. WSUD structures are generally small, decentralized systems intended to manage stormwater near the source. Many of these alternative techniques are based on infiltration which can affect both the urban sewer system and urban groundwater levels if widely implemented......Alternative methods for stormwater management in urban areas, also called Water Sensitive Urban Design (WSUD) methods, have become increasingly important for the mitigation of urban stormwater management problems such as high runoff volumes, combined sewage overflows, poor water quality......, and how these can be modeled in an integrated environment with distributed urban drainage and groundwater flow models. The thesis: 1. Identifies appropriate models of soakaways for use in an integrated and distributed urban water and groundwater modeling system 2. Develops a modeling concept that is able...

  4. Tracing of aerosol sources in an urban environment using chemical, Sr isotope, and mineralogical characterization.

    Science.gov (United States)

    Duarte, Regina M B O; Matos, João T V; Paula, Andreia S; Lopes, Sónia P; Ribeiro, Sara; Santos, José Francisco; Patinha, Carla; da Silva, Eduardo Ferreira; Soares, Rosário; Duarte, Armando C

    2017-04-01

    In the framework of two national research projects (ORGANOSOL and CN-linkAIR), fine particulate matter (PM 2.5 ) was sampled for 17 months at an urban location in the Western European Coast. The PM 2.5 samples were analyzed for organic carbon (OC), water-soluble organic carbon (WSOC), elemental carbon (EC), major water-soluble inorganic ions, mineralogical, and for the first time in this region, strontium isotope ( 87 Sr/ 86 Sr) composition. Organic matter dominates the identifiable urban PM 2.5 mass, followed by secondary inorganic aerosols. The acquired data resulted also in a seasonal overview of the carbonaceous and inorganic aerosol composition, with an important contribution from primary biomass burning and secondary formation processes in colder and warmer periods, respectively. The fossil-related primary EC seems to be continually present throughout the sampling period. The 87 Sr/ 86 Sr ratios were measured on both the labile and residual PM 2.5 fractions as well as on the bulk PM 2.5 samples. Regardless of the air mass origin, the residual fractions are more radiogenic (representative of a natural crustal dust source) than the labile fractions, whose 87 Sr/ 86 Sr ratios are comparable to that of seawater. The 87 Sr/ 86 Sr ratios and the mineralogical composition data further suggest that sea salt and mineral dust are important primary natural sources of fine aerosols throughout the sampling period.

  5. Study of Cl-containing urban aerosol particles by ion beam analytical methods

    Energy Technology Data Exchange (ETDEWEB)

    Angyal, A. [Laboratory of Ion Beam Applications (IBA LAB), Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), H-4001 Debrecen, P.O. Box 51 (Hungary); University of Debrecen - ATOMKI, Department of Environmental Physics, H-4001 Debrecen, P.O. Box 51 (Hungary); Kertesz, Zs., E-mail: zsofi@atomki.h [Laboratory of Ion Beam Applications (IBA LAB), Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), H-4001 Debrecen, P.O. Box 51 (Hungary); Szikszai, Z. [Laboratory of Ion Beam Applications (IBA LAB), Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), H-4001 Debrecen, P.O. Box 51 (Hungary); Szoboszlai, Z. [Laboratory of Ion Beam Applications (IBA LAB), Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), H-4001 Debrecen, P.O. Box 51 (Hungary); University of Debrecen - ATOMKI, Department of Environmental Physics, H-4001 Debrecen, P.O. Box 51 (Hungary)

    2010-06-15

    Fine (aerodynamic diameter < 2.5 {mu}m) and coarse (10 {mu}m {>=} aerodynamic diameter {>=} 2.5 {mu}m) mode urban aerosol samples were collected with 2-h time resolution in the frame of several sampling campaigns between 2007 and 2009 in downtown Debrecen, East-Hungary. The elemental composition (for Z {>=} 13) of the samples was measured by particle induced X-ray emission (PIXE). On this basis sources of urban aerosol were determined by factor analysis. For both size fractions a source characterized by high chlorine content were found. However, the origin of the Cl-containing aerosol could not be ascertained. Further investigation of samples characterized with high Cl content were done on the ATOMKI Scanning Nuclear Microprobe Facility in order to determine the possible chemical composition of these particles and thus the potential sources. Morphology, size and elemental composition for Z {>=} 6 of around 1000 coarse mode particles were determined by using STIM (Scanning Transmission Ion Microscopy), light-element PIXE and PIXE analytical methods. Hierarchical cluster analysis was performed on the obtained dataset in order to group the particles; correlations between different elements were also calculated. Five possible sources of Cl were identified, from which four were anthropogenic: winter salting of streets, agriculture through fertilizers, buildings and industry; the natural group was sea-salt.

  6. Measurement of aerosol size distribution by impaction and sedimentation An experimental study and data reduction

    International Nuclear Information System (INIS)

    Diouri, Mohamed.

    1981-09-01

    This study concerns essentially solid aerosols produced by combustion and more particulary the aerosol liberated by a sodium fire taken into account in safety studies related to sodium cooled nuclear reactors. The accurate determination of the aerosol size distribution depends on the selection device use. An experimental study of the parameters affecting the solid aerosol collection efficiency was made with the Andersen Mark II cascade impactor (blow off and bounce, electrical charge of particles, wall-loss). A sedimentation chamber was built and calibrated for the range between 4 and 10 μm. The second part describes a comparative study of different data reduction methods for the impactor and a new method for setting up the aerosol size distribution with data obtained by the sedimentation chamber [fr

  7. Particle characterization at rural, suburban and urban aerosol sampling sites in Hungary

    International Nuclear Information System (INIS)

    Borbely-Kiss, I.; Koltay, E.; Szabo, G.; Meszaros, E.; Molnar, A.; Bozo, L.

    1994-01-01

    The study of atmospheric aerosols originating from natural and anthropogenic processes is of basic importance for a detailed understanding of the physics and chemistry of the atmosphere. Particle Induced X-ray Emission (PIXE) technique has been used by the authors for studying regularly the elemental composition of rural, suburban, and urban aerosols collected at six sampling sites in Hungary. Observed data presented in terms of concentrations and regional signature values and evaluated wind sector partition and in transport modelling revealed the natural/anthropogenic contribution to the moderate air pollution here. Dry deposition velocities have been deduced for elements V, Cr, Mn, Co, Ni, Cu, Zn, Cd, and Pb. Model calculations based on annual emission data and observed elemental concentrations resulted in total dry and wet deposition masses of the above elements to the territory of the country. At the same time, deduced budget data for the emission and deposition of the constituents indicated whether the country represents a net source or a sink for the above mentioned elements in the regional aerosol transport between neighbouring countries. Evidences have been found for intrusion events of Saharan aerosol to the atmosphere of Hungary. Part of the data collected recently will be evaluated in the frame-work of an international co-ordinated research programme. (author)

  8. Vertical profiles of urban aerosol complex refractive index in the frame of ESQUIF airborne measurements

    Science.gov (United States)

    Raut, J.-C.; Chazette, P.

    2008-02-01

    A synergy between lidar, sunphotometer and in situ measurements has been applied to airborne observations performed during the Etude et Simulation de la QUalité de l'air en Ile-de-France (ESQUIF), enabling the retrieval of vertical profiles for the aerosol complex refractive index (ACRI) and single-scattering albedo with a vertical resolution of 200 m over Paris area. The averaged value over the entire planetary boundary layer (PBL) for the ACRI is close to 1.51(±0.02)-i0.017(±0.003) at 532 nm. The single-scattering albedo of the corresponding aerosols is found to be ~0.9 at the same wavelength. A good agreement is found with previous studies for urban aerosols. A comparison of vertical profiles of ACRI with simulations combining in situ measurements and relative humidity (RH) profiles has highlighted a modification in aerosol optical properties linked to their history and the origin of the air mass. The determination of ACRI in the atmospheric column enabled to retrieve vertical profiles of extinction coefficient in accordance with lidar profiles measurements.

  9. Aerosol removal due to precipitation and wind forcings in Milan urban area

    Science.gov (United States)

    Cugerone, Katia; De Michele, Carlo; Ghezzi, Antonio; Gianelle, Vorne

    2018-01-01

    Air pollution represents a critical issue in Milan urban area (Northern Italy). Here, the levels of fine particles increase, overcoming the legal limits, mostly in wintertime, due to favourable calm weather conditions and large heating and vehicular traffic emissions. The main goal of this work is to quantify the aerosol removal effect due to precipitation at the ground. At first, the scavenging coefficients have been calculated for aerosol particles with diameter between 0.25 and 3 μm. The average values of this coefficient vary between 2 ×10-5 and 5 ×10-5 s-1. Then, the aerosol removal induced separately by precipitation and wind have been compared through the introduction of a removal index. As a matter of fact, while precipitation leads to a proper wet scavenging of the particles from the atmosphere, high wind speeds cause enhanced particle dispersion and dilution, that locally bring to a tangible decrease of aerosol particles' number. The removal triggered by these two forcings showed comparable average values, but different trends. The removal efficiency of precipitation lightly increases with the increase of particle diameters and vice versa happens with strong winds.

  10. Retrieve Aerosol Concentration Based On Surface Model and Distribution of Concentration of PM2.5 ——A Case Study of Beijing

    Science.gov (United States)

    Cui, H.

    2017-12-01

    As China's economy continues to grow, urbanization continues to advance, along with growth in all areas to pollutant emissions in the air industry, air quality also continued to deteriorate. Aerosol concentrations as a measure of air quality of the most important part of are more and more people's attention. Traditional monitoring stations measuring aerosol concentration method is accurate, but time-consuming and can't be done simultaneously measure a large area, can only rely on data from several monitoring sites to predict the concentration of the panorama. Remote Sensing Technology retrieves aerosol concentrations being by virtue of their efficient, fast advantages gradually into sight. In this paper, by the method of surface model to start with the physical processes of atmospheric transport, innovative aerosol concentration coefficient proposed to replace the traditional aerosol concentrations, pushed to a set of retrieval of aerosol concentration coefficient method, enabling fast and efficient Get accurate air pollution target area. At the same paper also monitoring data for PM2.5 in Beijing were analyzed from different angles, from the perspective of the data summarized in Beijing PM2.5 concentration of time, space, geographical distribution and concentration of PM2.5 and explored the relationship between aerosol concentration coefficient and concentration of PM2.5.

  11. Aerosol indirect effect from turbulence-induced broadening of cloud-droplet size distributions

    Energy Technology Data Exchange (ETDEWEB)

    Chandrakar, Kamal Kant; Cantrell, Will; Chang, Kelken; Ciochetto, David; Niedermeier, Dennis; Ovchinnikov, Mikhail; Shaw, Raymond A.; Yang, Fan

    2016-11-28

    The influence of aerosol concentration on cloud droplet size distribution is investigated in a laboratory chamber that enables turbulent cloud formation through moist convection. The experiments allow steady-state microphysics to be achieved, with aerosol input balanced by cloud droplet growth and fallout. As aerosol concentration is increased the cloud droplet mean diameter decreases as expected, but the width of the size distribution also decreases sharply. The aerosol input allows for cloud generation in the limiting regimes of fast microphysics (τc < τt) for high aerosol concentration, and slow microphysics (τc > τt) for low aerosol concentration; here, τc is the phase relaxation time and τt is the turbulence correlation time. The increase in the width of the droplet size distribution for the low aerosol limit is consistent with larger variability of supersaturation due to the slow microphysical response. A stochastic differential equation for supersaturation predicts that the standard deviation of the squared droplet radius should increase linearly with a system time scale defined as τs-1c-1 + τt-1, and the measurements are in excellent agreement with this finding. This finding underscores the importance of droplet size dispersion for the aerosol indirect effect: increasing aerosol concentration not only suppresses precipitation formation through reduction of the mean droplet diameter, but perhaps more importantly, through narrowing of the droplet size distribution due to reduced supersaturation fluctuations. Supersaturation fluctuations in the low aerosol / slow microphysics limit are likely of leading importance for precipitation formation.

  12. Evolution of Multispectral Aerosol Absorption Properties in a Biogenically-Influenced Urban Environment during the CARES Campaign

    Energy Technology Data Exchange (ETDEWEB)

    Gyawali, Madhu; Arnott, W.; Zaveri, Rahul; Song, Chen; Flowers, Bradley; Dubey, Manvendra; Setyan, Ari; Zhang, Qi; China, Swarup; Mazzoleni, Claudio; Gorkowski, Kyle; Subramanian, R.; Moosmüller, Hans

    2017-11-01

    We present the evolution of multispectral optical properties as urban aerosols aged and interacted with biogenic emissions resulting in stronger short wavelength absorption and formation of moderately brown secondary organic aerosols. Ground-based aerosol measurements were made during June 2010 within the Sacramento urban area (site T0) and at a 40-km downwind location (site T1) in the forested Sierra Nevada foothills area. Data on black carbon and non-refractory aerosol mass and composition were collected at both sites. In addition, photoacoustic (PA) instruments with integrating nephelometers were used to measure spectral absorption and scattering coefficients for wavelengths ranging from 355 to 870 nm. The daytime absorption Ångström exponent (AAE) indicated a modest wavelength-dependent enhancement of absorption at both sites throughout the study. From the 22nd to the 28th of June, secondary organic aerosol mass increased significantly at both sites due to increased biogenic emissions coupled with intense photochemical activity and air mass recirculation in the area. During this period, the median BC mass-normalized absorption cross-section (MAC) values for 405 nm and 532 nm at T1 increased by ~23% and ~35%, respectively, compared to the relatively less aged urban emissions at the T0 site. In contrast, the average MAC values for the 870 nm wavelength were similar for both sites. These results suggest formation of moderately brown secondary organic aerosols in biogenically-influenced urban air.

  13. Highly time-resolved urban aerosol characteristics during springtime in Yangtze River Delta, China: insights from soot particle aerosol mass spectrometry

    Directory of Open Access Journals (Sweden)

    J. Wang

    2016-07-01

    Full Text Available In this work, the Aerodyne soot particle – aerosol mass spectrometer (SP-AMS was deployed for the first time during the spring of 2015 in urban Nanjing, a megacity in the Yangtze River Delta (YRD of China, for online characterization of the submicron aerosols (PM1. The SP-AMS enables real-time and fast quantification of refractory black carbon (rBC simultaneously with other non-refractory species (ammonium, sulfate, nitrate, chloride, and organics. The average PM1 concentration was found to be 28.2 µg m−3, with organics (45 % as the most abundant component, following by sulfate (19.3 %, nitrate (13.6 %, ammonium (11.1 %, rBC (9.7 %, and chloride (1.3 %. These PM1 species together can reconstruct ∼ 44 % of the light extinction during this campaign based on the IMPROVE method. Chemically resolved mass-based size distributions revealed that small particles especially ultrafine ones (< 100 nm vacuum aerodynamic diameter were dominated by organics and rBC, while large particles had significant contributions from secondary inorganic species. Source apportionment of organic aerosols (OA yielded four OA subcomponents, including hydrocarbon-like OA (HOA, cooking-related OA (COA, semi-volatile oxygenated OA (SV-OOA, and low-volatility oxygenated OA (LV-OOA. Overall, secondary organic aerosol (SOA, equal to the sum of SV-OOA and LV-OOA dominated the total OA mass (55.5 %, but primary organic aerosol (POA, equal to the sum of HOA and COA can outweigh SOA in the early morning and evening due to enhanced human activities. High OA concentrations were often associated with high mass fractions of POA and rBC, indicating the important role of anthropogenic emissions during heavy pollution events. The diurnal cycles of nitrate, chloride, and SV-OOA both showed good anti-correlations with air temperatures, suggesting their variations were likely driven by thermodynamic equilibria and gas-to-particle partitioning. On the other hand

  14. AOD Distributions and Trends of Major Aerosol Species over a Selection of the World's Most Populated Cities Based on the 1st Version of NASA's MERRA Aerosol Reanalysis

    Science.gov (United States)

    Provencal, Simon; Kishcha, Pavel; da Silva, Arlindo M.; Elhacham, Emily; Alpert, Pinhas

    2017-01-01

    NASA recently extended the Modern-Era Retrospective Analysis for Research and Application (MERRA) with an atmospheric aerosol reanalysis which includes five particulate species: sulfate, organic matter, black carbon, mineral dust and sea salt. The MERRA Aerosol Reanalysis (MERRAero) is an innovative tool to study air quality issues around the world for its global and constant coverage and its distinction of aerosol speciation expressed in the form of aerosol optical depth (AOD). The purpose of this manuscript is to apply MERRAero to the study of urban air pollution at the global scale by analyzing the AOD over a period of 13 years (2003-2015) and over a selection of 200 of the world's most populated cities in order to assess the impacts of urbanization, industrialization, air quality regulations and regional transport which affect urban aerosol load. Environmental regulations and the recent global economic recession have helped to decrease the AOD and sulfate aerosols in most cities in North America, Europe and Japan. Rapid industrialization in China over the last two decades resulted in Chinese cities having the highest AOD values in the world. China has nevertheless recently implemented emission control measures which are showing early signs of success in many cities of Southern China where AOD has decreased substantially over the last 13 years. The AOD over South American cities, which is dominated by carbonaceous aerosols, has also decreased over the last decade due to an increase in commodity prices which slowed deforestation activities in the Amazon rainforest. At the opposite, recent urbanization and industrialization in India and Bangladesh resulted in a strong increase of AOD, sulfate and carbonaceous aerosols in most cities of these two countries. The AOD over most cities in Northern Africa and Western Asia changed little over the last decade. Emissions of natural aerosols, which cities in these two regions tend to be mostly composed of, don't tend to

  15. Spaceborne Remote Sensing of Aerosol Type: Global Distribution, Model Evaluation and Translation into Chemical Speciation

    Science.gov (United States)

    Kacenelenbogen, M. S.; Tan, Q.; Johnson, M. S.; Burton, S. P.; Redemann, J.; Hasekamp, O. P.; Dawson, K. W.; Hair, J. W.; Ferrare, R. A.; Butler, C. F.; Holben, B. N.; Beyersdorf, A. J.; Ziemba, L. D.; Froyd, K. D.; Dibb, J. E.; Shingler, T.; Sorooshian, A.; Jimenez, J. L.; Campuzano Jost, P.; Jacob, D.; Kim, P. S.; Travis, K.; Lacagnina, C.

    2016-12-01

    It is essential to evaluate and refine aerosol classification methods applied to passive satellite remote sensing. We have developed an aerosol classification algorithm (called Specified Clustering and Mahalanobis Classification, SCMC) that assigns an aerosol type to multi-parameter retrievals by spaceborne, airborne or ground-based passive remote sensing instruments [1]. The aerosol types identified by our scheme are pure dust, polluted dust, urban-industrial/developed economy, urban-industrial/developing economy, dark biomass smoke, light biomass smoke and pure marine. We apply the SCMC method to inversions from the ground-based AErosol RObotic NETwork (AERONET [2]) and retrievals from the space-borne Polarization and Directionality of Earth's Reflectances instrument (POLDER, [3]). The POLDER retrievals that we use differ from the standard POLDER retrievals [4] as they make full use of multi-angle, multispectral polarimetric data [5]. We analyze agreement in the aerosol types inferred from both AERONET and POLDER and evaluate GEOS-Chem [6] simulations over the globe. Finally, we use in-situ observations from the SEAC4RS airborne field experiment to bridge the gap between remote sensing-inferred qualitative SCMC aerosol types and their corresponding quantitative chemical speciation. We apply the SCMC method to airborne in-situ observations from the NASA Langley Aerosol Research Group Experiment (LARGE, [7]) and the Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe (DASH-SP, [8]) instruments; we then relate each coarsely defined SCMC type to a sum of percentage of individual aerosol species, using in-situ observations from the Particle Analysis by Laser Mass Spectrometry (PALMS, [9]), the Soluble Acidic Gases and Aerosol (SAGA, [10]), and the High - Resolution Time - of - Flight Aerosol Mass Spectrometer (HR ToF AMS, [11]). [1] Russell P. B., et al., JGR, 119.16 (2014) [2] Holben B. N., et al., RSE, 66.1 (1998) [3] Tanré D., et al., AMT, 4.7 (2011

  16. The impact of aerosol vertical distribution on aerosol optical depth retrieval using CALIPSO and MODIS data: Case study over dust and smoke regions

    Science.gov (United States)

    Wu, Yerong; de Graaf, Martin; Menenti, Massimo

    2017-08-01

    Global quantitative aerosol information has been derived from MODerate Resolution Imaging SpectroRadiometer (MODIS) observations for decades since early 2000 and widely used for air quality and climate change research. However, the operational MODIS Aerosol Optical Depth (AOD) products Collection 6 (C6) can still be biased, because of uncertainty in assumed aerosol optical properties and aerosol vertical distribution. This study investigates the impact of aerosol vertical distribution on the AOD retrieval. We developed a new algorithm by considering dynamic vertical profiles, which is an adaptation of MODIS C6 Dark Target (C6_DT) algorithm over land. The new algorithm makes use of the aerosol vertical profile extracted from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) measurements to generate an accurate top of the atmosphere (TOA) reflectance for the AOD retrieval, where the profile is assumed to be a single layer and represented as a Gaussian function with the mean height as single variable. To test the impact, a comparison was made between MODIS DT and Aerosol Robotic Network (AERONET) AOD, over dust and smoke regions. The results show that the aerosol vertical distribution has a strong impact on the AOD retrieval. The assumed aerosol layers close to the ground can negatively bias the retrievals in C6_DT. Regarding the evaluated smoke and dust layers, the new algorithm can improve the retrieval by reducing the negative biases by 3-5%.

  17. Aerosol particle size distribution in the stratosphere retrieved from SCIAMACHY limb measurements

    Science.gov (United States)

    Malinina, Elizaveta; Rozanov, Alexei; Rozanov, Vladimir; Liebing, Patricia; Bovensmann, Heinrich; Burrows, John P.

    2018-04-01

    health, stratospheric aerosol plays an important role in atmospheric chemistry and climate change. In particular, information about the amount and distribution of stratospheric aerosols is required to initialize climate models, as well as validate aerosol microphysics models and investigate geoengineering. In addition, good knowledge of stratospheric aerosol loading is needed to increase the retrieval accuracy of key trace gases (e.g. ozone or water vapour) when interpreting remote sensing measurements of the scattered solar light. The most commonly used characteristics to describe stratospheric aerosols are the aerosol extinction coefficient and Ångström coefficient. However, the use of particle size distribution parameters along with the aerosol number density is a more optimal approach. In this paper we present a new retrieval algorithm to obtain the particle size distribution of stratospheric aerosol from space-borne observations of the scattered solar light in the limb-viewing geometry. While the mode radius and width of the aerosol particle size distribution are retrieved, the aerosol particle number density profile remains unchanged. The latter is justified by a lower sensitivity of the limb-scattering measurements to changes in this parameter. To our knowledge this is the first data set providing two parameters of the particle size distribution of stratospheric aerosol from space-borne measurements of scattered solar light. Typically, the mode radius and w can be retrieved with an uncertainty of less than 20 %. The algorithm was successfully applied to the tropical region (20° N-20° S) for 10 years (2002-2012) of SCIAMACHY observations in limb-viewing geometry, establishing a unique data set. Analysis of this new climatology for the particle size distribution parameters showed clear increases in the mode radius after the tropical volcanic eruptions, whereas no distinct behaviour of the absolute distribution width could be identified. A tape recorder

  18. Effects of urbanization on carnivore species distribution and richness

    Science.gov (United States)

    Ordenana, Miguel A.; Crooks, Kevin R.; Boydston, Erin E.; Fisher, Robert N.; Lyren, Lisa M.; Siudyla, Shalene; Haas, Christopher D.; Harris, Sierra; Hathaway, Stacie A.; Turschak, Greta M.; Miles, A. Keith; Van Vuren, Dirk H.

    2010-01-01

    Urban development can have multiple effects on mammalian carnivore communities. We conducted a meta-analysis of 7,929 photographs from 217 localities in 11 camera-trap studies across coastal southern California to describe habitat use and determine the effects of urban proximity (distance to urban edge) and intensity (percentage of area urbanized) on carnivore occurrence and species richness in natural habitats close to the urban boundary. Coyotes (Canis latrans) and bobcats (Lynx rufus) were distributed widely across the region. Domestic dogs (Canis lupus familiaris), striped skunks (Mephitis mephitis), raccoons (Procyon lotor), gray foxes (Urocyon cinereoargenteus), mountain lions (Puma concolor), and Virginia opossums (Didelphis virginiana) were detected less frequently, and long-tailed weasels (Mustela frenata), American badgers (Taxidea taxus), western spotted skunks (Spilogale gracilis), and domestic cats (Felis catus) were detected rarely. Habitat use generally reflected availability for most species. Coyote and raccoon occurrence increased with both proximity to and intensity of urbanization, whereas bobcat, gray fox, and mountain lion occurrence decreased with urban proximity and intensity. Domestic dogs and Virginia opossums exhibited positive and weak negative relationships, respectively, with urban intensity but were unaffected by urban proximity. Striped skunk occurrence increased with urban proximity but decreased with urban intensity. Native species richness was negatively associated with urban intensity but not urban proximity, probably because of the stronger negative response of individual species to urban intensity.

  19. Assessment of aerosols optical properties and radiative forcing over an Urban site in North-Western India.

    Science.gov (United States)

    Mor, Vikram; Dhankhar, Rajesh; Attri, S D; Soni, V K; Sateesh, M; Taneja, Kanika

    2017-05-01

    The present work is aimed to analyze aerosols optical properties and to estimate aerosol radiative forcing (ARF) from January to December 2013, using sky radiometer data over Rohtak, an urban site in North-Western India. The results reveal strong wavelength dependency of aerosol optical depth (AOD), with high values of AOD at shorter wavelengths and lower values at longer wavelength during the study period. The highest AOD values of 1.07 ± 0.45 at 500 nm were observed during July. A significant decline in Ångström exponent was observed during April-May, which represents the dominance of coarse mode particles due to dust-raising convective activities. Aerosols' size distribution exhibits a bimodal structure with fine mode particles around 0.17 µm and coarse mode particles with a radius around 5.28 µm. Single scattering albedo values were lowest during November-December at all wavelengths, ranging from 0.87 to 0.76, which corresponds to the higher absorption during this period. Aerosols optical properties retrieved during observation period are used as input for SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) to estimate the direct ARF at the surface, in the atmosphere and at the top of the atmosphere (TOA). The ARF at the TOA, surface and in the atmosphere are found to be in the range of -4.98 to -19.35 W m -2 , -8.01 to -57.66 W m -2 and +3.02 to +41.64 W m -2 , respectively. The averaged forcing for the whole period of observations at the TOA is -11.26 W m -2 , while at the surface it is -38.64 W m -2 , leading to atmospheric forcing of 27.38 W m -2 . The highest (1.168 K day -1 ) values of heating rate was estimated during November, whereas the lowest value (0.084 K day -1 ) was estimated for the February.

  20. Characteristics of fine and coarse particles of natural and urban aerosols of Brazil

    International Nuclear Information System (INIS)

    Orsini, C.M.Q.; Tabacniks, M.H.; Artaxo Netto, P.E.; Andrade, M.F.; Kerr, A.

    1986-02-01

    Fine and coarse particles have been sampled from 1982 to 1985 in one natural forest seacoast site (Jureia) and five urban-industrial cities (Vitoria, Salvador, Porto Alegre, Sao Paulo, and Belo Horizonte). The time variations of concentrations in air and the relative elemental compositions of fine and coarse particle fractions, sampled by Nuclepore stacked filter units (SFU), have been determined gravimetrically and by PIXE analysis, respectively. Enrichment factors and correlation coefficients of the trace elements measured lead to unambiguous characterization of soil dust and sea salt, both major aerosol sources that emit coarse particles, and soil dust is also a significant source of fine particles. (Author) [pt

  1. The Influence of Emission Location on the Magnitude and Spatial Distribution of Aerosols' Climate Effects

    Science.gov (United States)

    Persad, G.; Caldeira, K.

    2017-12-01

    The global distribution of anthropogenic aerosol emissions has evolved continuously since the preindustrial era - from 20th century North American and Western European emissions hotspots to present-day South and East Asian ones. With this comes a relocation of the regional radiative, dynamical, and hydrological impacts of aerosol emissions, which may influence global climate differently depending on where they occur. A lack of understanding of this relationship between aerosol emissions' location and their global climate effects, however, obscures the potential influence that aerosols' evolving geographic distribution may have on global and regional climate change—a gap which we address in this work. Using a novel suite of experiments in the CESM CAM5 atmospheric general circulation model coupled to a slab ocean, we systematically test and analyze mechanisms behind the relative climate impact of identical black carbon and sulfate aerosol emissions located in each of 8 past, present, or projected future major emissions regions. Results indicate that historically high emissions regions, such as North America and Western Europe, produce a stronger cooling effect than current and projected future high emissions regions. Aerosol emissions located in Western Europe produce 3 times the global mean cooling (-0.34 °C) as those located in East Africa or India (-0.11 °C). The aerosols' in-situ radiative effects remain relatively confined near the emissions region, but large distal cooling results from remote feedback processes - such as ice albedo and cloud changes - that are excited more strongly by emissions from certain regions than others. Results suggest that aerosol emissions from different countries should not be considered equal in the context of climate mitigation accounting, and that the evolving geographic distribution of aerosol emissions may have a substantial impact on the magnitude and spatial distribution of global climate change.

  2. Lidar Investigation of Aerosol Pollution Distribution near a Coal Power Plant

    Science.gov (United States)

    Mitsev, TS.; Kolarov, G.

    1992-01-01

    Using aerosol lidars with high spatial and temporal resolution with the possibility of real-time data interpretation can solve a large number of ecological problems related to the aerosol-field distribution and variation and the structure of convective flows. Significantly less expensive specialized lidars are used in studying anthropogenic aerosols in the planetary boundary layer. Here, we present results of lidar measurements of the mass-concentration field around a coal-fired power plant with intensive local aerosol sources. We studied the pollution evolution as a function of the emission dynamics and the presence of retaining layers. The technique used incorporates complex analysis of three types of lidar mapping: horizontal map of the aerosol field, vertical cross-section map, and a series of profiles along a selected path. The lidar-sounding cycle was performed for the time of atmosphere's quasi-stationarity.

  3. Lidar investigation of aerosol pollution distribution near a coal power plant

    International Nuclear Information System (INIS)

    Mitsev, T.S.; Kolarov, G.

    1992-01-01

    Using aerosol lidars with high spatial and temporal resolution with the possibility of real-time data interpretation can solve a large number of ecological problems related to the aerosol-field distribution and variation and the structure of convective flows. Significantly less expensive specialized lidars are used in studying anthropogenic aerosols in the planetary boundary layer. Here, results are presented of lidar measurements of the mass-concentration field around a coal-fired power plant with intensive local aerosol sources. The authors studied the pollution evolution as a function of the emission dynamics and the presence of retaining layers. The technique used incorporates complex analysis of three types of lidar mapping: horizontal map of the aerosol field, vertical cross-section map, and a series of profiles along a selected path. The lidar-sounding cycle was performed for the time of atmosphere's quasi-stationarity

  4. Aerosol Extinction Profile Mapping with Lognormal Distribution Based on MPL Data

    Science.gov (United States)

    Lin, T. H.; Lee, T. T.; Chang, K. E.; Lien, W. H.; Liu, G. R.; Liu, C. Y.

    2017-12-01

    This study intends to challenge the profile mapping of aerosol vertical distribution by mathematical function. With the similarity in distribution pattern, lognormal distribution is examined for mapping the aerosol extinction profile based on MPL (Micro Pulse LiDAR) in situ measurements. The variables of lognormal distribution are log mean (μ) and log standard deviation (σ), which will be correlated with the parameters of aerosol optical depht (AOD) and planetary boundary layer height (PBLH) associated with the altitude of extinction peak (Mode) defined in this study. On the base of 10 years MPL data with single peak, the mapping results showed that the mean error of Mode and σ retrievals are 16.1% and 25.3%, respectively. The mean error of σ retrieval can be reduced to 16.5% under the cases of larger distance between PBLH and Mode. The proposed method is further applied to MODIS AOD product in mapping extinction profile for the retrieval of PM2.5 in terms of satellite observations. The results indicated well agreement between retrievals and ground measurements when aerosols under 525 meters are well-mixed. The feasibility of proposed method to satellite remote sensing is also suggested by the case study. Keyword: Aerosol extinction profile, Lognormal distribution, MPL, Planetary boundary layer height (PBLH), Aerosol optical depth (AOD), Mode

  5. Mass and chemically speciated size distribution of Prague aerosol using an aerosol dryer - The influence of air mass origin

    Czech Academy of Sciences Publication Activity Database

    Schwarz, Jaroslav; Štefancová, Lucia; Maenhaut, W.; Smolík, Jiří; Ždímal, Vladimír

    2012-01-01

    Roč. 437, OCT 15 (2012), s. 348-362 ISSN 0048-9697 R&D Projects: GA ČR GA205/09/2055; GA ČR GAP209/11/1342; GA MŠk ME 941 Grant - others:SRF GU(BE) 01S01306 Institutional support: RVO:67985858 Keywords : atmospheric aerosols * mass size distribution * chemical composition Subject RIV: DI - Air Pollution ; Quality Impact factor: 3.258, year: 2012

  6. Distributions and climate effects of atmospheric aerosols from the preindustrial era to 2100 along Representative Concentration Pathways (RCPs simulated using the global aerosol model SPRINTARS

    Directory of Open Access Journals (Sweden)

    T. Takemura

    2012-12-01

    Full Text Available Global distributions and associated climate effects of atmospheric aerosols were simulated using a global aerosol climate model, SPRINTARS, from 1850 to the present day and projected forward to 2100. Aerosol emission inventories used by the Coupled Model Intercomparison Project Phase 5 (CMIP5 were applied to this study. Scenarios based on the Representative Concentration Pathways (RCPs were used for the future projection. Aerosol loading in the atmosphere has already peaked and is now reducing in Europe and North America. However, in Asia where rapid economic growth is ongoing, aerosol loading is estimated to reach a maximum in the first half of this century. Atmospheric aerosols originating from the burning of biomass have maintained high loadings throughout the 21st century in Africa, according to the RCPs. Evolution of the adjusted forcing by direct and indirect aerosol effects over time generally correspond to the aerosol loading. The probable future pathways of global mean forcing differ based on the aerosol direct effect for different RCPs. Because aerosol forcing will be close to the preindustrial level by the end of the 21st century for all RCPs despite the continuous increases in greenhouse gases, global warming will be accelerated with reduced aerosol negative forcing.

  7. Interpretation of aerosol trace metal particle size distributions

    International Nuclear Information System (INIS)

    Johansson, T.B.; Van Grieken, R.E.; Winchester, J.W.

    1974-01-01

    Proton-induced X-ray emission (PIXE) analysis is capable of rapid routine determination of 10--15 elements present in amounts greater than or equal to 1 ng simultaneously in aerosol size fractions as collected by single orifice impactors over short periods of time. This enables detailed study of complex relationships between elements detected. Since absolute elemental concentrations may be strongly influenced by meteorological and topographical conditions, it is useful to normalize to a reference element. Comparison between the ratios of concentrations with aerosol and corresponding values for anticipated sources may lead to the identification of important sources for the elements. Further geochemical insights may be found through linear correlation coefficients, regression analysis, and cluster analysis. By calculating correlations for elemental pairs, an indication of the degree of covariance between the elements is obtained. Preliminary results indicate that correlations may be particle size dependent. A high degree of covariance may be caused either by a common source or may only reflect the conservative nature of the aerosol. In a regression analysis, by plotting elemental pairs and estimating the regression coefficients, we may be able to conclude if there is more than one source operating for a given element in a certain size range. Analysis of clustering of several elements, previously investigated for aerosol filter samples, can be applied to the analysis of aerosol size fractions. Careful statistical treatment of elemental concentrations as a function of aerosol particle size may thus yield significant information on the generation, transport and deposition of trace metals in the atmosphere

  8. Universal scaling of the distribution of land in urban areas

    Science.gov (United States)

    Riascos, A. P.

    2017-09-01

    In this work, we explore the spatial structure of built zones and green areas in diverse western cities by analyzing the probability distribution of areas and a coefficient that characterize their respective shapes. From the analysis of diverse datasets describing land lots in urban areas, we found that the distribution of built-up areas and natural zones in cities obey inverse power laws with a similar scaling for the cities explored. On the other hand, by studying the distribution of shapes of lots in urban regions, we are able to detect global differences in the spatial structure of the distribution of land. Our findings introduce information about spatial patterns that emerge in the structure of urban settlements; this knowledge is useful for the understanding of urban growth, to improve existing models of cities, in the context of sustainability, in studies about human mobility in urban areas, among other applications.

  9. Effective Density and Mixing State of Aerosol Particles in a Near-Traffic Urban Environment

    DEFF Research Database (Denmark)

    Rissler, Jenny; Nordin, Erik Z; Eriksson, Axel C

    2014-01-01

    -range transport from polluted continental areas. The effective density of each group was relatively stable over time, especially of the soot aggregates, which had effective densities similar to those observed in laboratory studies of fresh diesel exhaust emissions. When heated to 300 °C, the soot aggregate......In urban environments, airborne particles are continuously emitted, followed by atmospheric aging. Also, particles emitted elsewhere, transported by winds, contribute to the urban aerosol. We studied the effective density (mass-mobility relationship) and mixing state with respect to the density...... and more dense particles. Both groups were present at each size in varying proportions. Two types of temporal variability in the relative number fraction of the two groups were found: soot correlated with intense traffic in a diel pattern and dense particles increased during episodes with long...

  10. Measurement and analysis of the concentration and size distribution of aerosols in a copper mine

    International Nuclear Information System (INIS)

    Li Dehong; Zhuo Weihai; Huang Gang; Su Xu; Sun Quanfu

    2008-01-01

    Objective: To explore the general characteristics of the concentration and size distribution of aerosols in a mine. Methods: In different areas of a non-uranium mine, the particle number and mass concentration of aerosols were surveyed with a condensation particle counter and a personal aerosol monitor, respectively, and the size distribution of aerosols larger than 1 μm in size was estimated according to the size- selective measurements of mass concentrations. The size distribution of submicron aerosols was evaluated based on the method of screen diffusion battery (SOB), and the measurements were performed in both inside and outside of a control room. Results: The mass concentration of inhaled particles (PM10) was averaged to be 0.42 mg/m 3 in the whole mine, and it varied with different working areas and significantly affected with human activities. In the mine, particles lager than 1 μm in size widely distributed, while the particles less than 5 nm in size were seldom observed. Conclusions: The characteristics of aerosol significantly change with different working areas, human activities and Antilation condition in mine. The dose contribution from inhaled radioactive particles larger than 1 μm in size should be considered in mine. (authors)

  11. The effect of increase in humidity on the size and activity distributions of radon progeny laden aerosols from hydrocarbon combustion

    International Nuclear Information System (INIS)

    Khan, Atika; Phillips, C.R.

    1988-01-01

    The effects of a humidity increase on the distributions of aerosol size and activity for hydrocarbon combustion aerosols laden with radon progeny were determined. Pre-humidification aerosol conditions were 20 0 C and 35% RH. Post-humidification aerosol conditions were 37 0 C and 100% RH, intended to simulate conditions in the human respiratory tract. Using kerosene combustion aerosols, a growth factor of 1.3 ± 0.2 (standard deviation) was found for both the aerosol median diameter and the activity median diameter. (author)

  12. Determination of the particle size distribution of aerosols by means of a diffusion battery

    International Nuclear Information System (INIS)

    Maigne, J.P.

    1978-09-01

    The different methods allowing to determine the particle size distribution of aerosols by means of diffusion batteries are described. To that purpose, a new method for the processing of experimental data (percentages of particles trapped by the battery vs flow rate) was developed on the basis of calculation principles which are described and assessed. This method was first tested by numerical simulation from a priori particle size distributions and then verified experimentally using a fine uranine aerosol whose particle size distribution as determined by our method was compared with the distribution previously obtained by electron microscopy. The method can be applied to the determination of particle size distribution spectra of fine aerosols produced by 'radiolysis' of atmospheric gaseous impurities. Two other applications concern the detection threshold of the condensation nuclei counter and the 'critical' radii of 'radiolysis' particles [fr

  13. CFD modelling for atmospheric pollutants/aerosols studies within the complex terrains of urban areas and industrial sites

    Czech Academy of Sciences Publication Activity Database

    Střižík, Michal; Zelinger, Z.; Nevrlý, Václav; Kubát, P.; Berger, P.; Černý, A.; Engst, P.; Bitala, Petr; Janečková, R.; Grigorová, Eva; Bestová, I.; Čadil, J.; Danihelka, P.; Kadeřábek, P.; Kozubková, M.; Drábková, S.; Hartman, D.; Bojko, M.; Zavila, O.

    2014-01-01

    Roč. 54, č. 1 (2014), s. 73-90 ISSN 0957-4352 R&D Projects: GA MV VG20132015108 Institutional support: RVO:61388998 Keywords : aerosol formation * computational fluid dynamic modeling * NH4NO3 aerosol * pollution dispersion * spatial distribution * turbulent environment Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 0.433, year: 2014

  14. Measurement of particle size distribution and mass concentration of nuclear fuel aerosols

    International Nuclear Information System (INIS)

    Pickering, S.

    1982-01-01

    The particle size distribution and particle mass concentration of a nuclear fuel aerosol is measured by admitting the aerosol into a vertically-extending container, positioning an alpha particle detector within the container so that its window is horizontal and directed vertically, stopping the admission of aerosol into the container, detecting the alpha-activity of the particles of the aerosol sedimenting onto the detector window (for example in a series of equal time intervals until a constant level is reached), and converting the alpha-activity measurements into particle size distribution and/or particle mass concentration measurements. The detector is attached to a pivotted arm and by raising a counterweight can be lowered from the container for cleaning. (author)

  15. Underground measurements of aerosol in radon and thoron progeny activity distributions

    International Nuclear Information System (INIS)

    Khan, A.; Bandi, F.; Phillips, C.R.; Duport, P.

    1990-01-01

    Aerosol and activity distributions of 218 Polonium, 214 Lead, 214 Bismuth, and 212 Lead were determined in two different underground mining environments by means of an optimized time-delay counting scheme and diffusion batteries. In one environment, diesel equipment was operating; and in the other, electrically powered equipment. The two environments differed significantly in total aerosol concentration. In the diesel environment, in particular, aerosol concentrations were unsteady, and fluctuated with vehicular traffic and mining activities. As measured by radon progeny disequilibrium, the age of the air ranged from about 25 to 60 minutes. Thoron working levels were of the same order as radon working levels. In this paper, comparisons are made between the aerosol and activity size distributions in both the diesel and electric mine

  16. Seasonal variability of aerosol concentration and size distribution in Cape Verde using a continuous aerosol optical spectrometer

    Directory of Open Access Journals (Sweden)

    Casimiro Adrião Pio

    2014-05-01

    Full Text Available One year of, almost continuous, measurements of aerosol optical properties and chemical composition were performed at the outskirts of Praia, Santiago Island, Cape Verde, within the framework of CV-DUST (Atmospheric aerosol in Cape Verde region: seasonal evaluation of composition, sources and transport research project, during 2011. This article reports the aerosol number and mass concentration measurements using a GRIMM Optical Aerosol Spectrometer that provides number size discrimination into 31 size ranges from 0.25 to 32 µm. Time series of 5 min average PM10 concentrations revealed peak values higher than 1000 µg.m-3 during winter dust storm events originating over Northern Africa. The 24 hours average concentrations exceeded the World Health Organization (WHO guidelines for PM2.5 and PM10 in 20% and 30% of the 2001 days, respectively. Annual average mass concentrations (±standard deviation for PM1, PM2.5 and PM10 were 5±5, 19±21 and 48±64 µg.m-3, respectively. The annual PM2.5 and PM10 values were also above the limits prescribed by the WHO (10 and 20 µg.m-3, respectively. The aerosol mass size distribution revealed two main modes for particles smaller than 10 µm: a fine mode (0.7-0.8 µm, which possibly results of gas to particle conversion processes; and a coarse mode with maxima at 3-4 µm, which is associated with desert dust and sea salt sources. Within the coarse mode two sub-modes with maxima at 5-6 µm and 10-12 µm were frequently present.

  17. Changes in concentration and size distribution of aerosols during ...

    Indian Academy of Sciences (India)

    It is proposed that the preferential growth and sedimentation of the coarse mode hygroscopic particles in the ... ing of aerosols by fog droplets during their sedi- mentation to the .... drawn through individual silicon conductive tubes of 0.5 cm ...

  18. Studies on aerosol properties during ICARB–2006 campaign period ...

    Indian Academy of Sciences (India)

    Synchronous measurements of Aerosol Optical Depth (AOD), Black Carbon (BC) aerosol mass concentration and aerosol particle size distribution were carried out during the campaign period at tropical urban regions of Hyderabad, India. Daily satellite datasets of DMSP-OLS were processed for night-time forest fires over ...

  19. The impact of precipitation evaporation on the atmospheric aerosol distribution in EC-Earth v3.2.0

    Science.gov (United States)

    de Bruine, Marco; Krol, Maarten; van Noije, Twan; Le Sager, Philippe; Röckmann, Thomas

    2018-04-01

    The representation of aerosol-cloud interaction in global climate models (GCMs) remains a large source of uncertainty in climate projections. Due to its complexity, precipitation evaporation is either ignored or taken into account in a simplified manner in GCMs. This research explores various ways to treat aerosol resuspension and determines the possible impact of precipitation evaporation and subsequent aerosol resuspension on global aerosol burdens and distribution. The representation of aerosol wet deposition by large-scale precipitation in the EC-Earth model has been improved by utilising additional precipitation-related 3-D fields from the dynamical core, the Integrated Forecasting System (IFS) general circulation model, in the chemistry and aerosol module Tracer Model, version 5 (TM5). A simple approach of scaling aerosol release with evaporated precipitation fraction leads to an increase in the global aerosol burden (+7.8 to +15 % for different aerosol species). However, when taking into account the different sizes and evaporation rate of raindrops following Gong et al. (2006), the release of aerosols is strongly reduced, and the total aerosol burden decreases by -3.0 to -8.5 %. Moreover, inclusion of cloud processing based on observations by Mitra et al. (1992) transforms scavenged small aerosol to coarse particles, which enhances removal by sedimentation and hence leads to a -10 to -11 % lower aerosol burden. Finally, when these two effects are combined, the global aerosol burden decreases by -11 to -19 %. Compared to the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite observations, aerosol optical depth (AOD) is generally underestimated in most parts of the world in all configurations of the TM5 model and although the representation is now physically more realistic, global AOD shows no large improvements in spatial patterns. Similarly, the agreement of the vertical profile with Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP

  20. Radiative response of biomass-burning aerosols over an urban atmosphere in northern peninsular Southeast Asia.

    Science.gov (United States)

    Pani, Shantanu Kumar; Lin, Neng-Huei; Chantara, Somporn; Wang, Sheng-Hsiang; Khamkaew, Chanakarn; Prapamontol, Tippawan; Janjai, Serm

    2018-08-15

    A large concentration of finer particulate matter (PM 2.5 ), the primary air-quality concern in northern peninsular Southeast Asia (PSEA), is believed to be closely related to large amounts of biomass burning (BB) particularly in the dry season. In order to quantitatively estimate the contributions of BB to aerosol radiative effects, we thoroughly investigated the physical, chemical, and optical properties of BB aerosols through the integration of ground-based measurements, satellite retrievals, and modelling tools during the Seven South East Asian Studies/Biomass-burning Aerosols & Stratocumulus Environment: Lifecycles & Interactions Experiment (7-SEAS/BASELInE) campaign in 2014. Clusters were made on the basis of measured BB tracers (Levoglucosan, nss-K + , and NO 3 - ) to classify the degree of influence from BB over an urban atmosphere, viz., Chiang Mai (18.795°N, 98.957°E, 354m.s.l.), Thailand in northern PSEA. Cluster-wise contributions of BB to PM 2.5 , organic carbon, and elemental carbon were found to be 54-79%, 42-79%, and 39-77%, respectively. Moreover, the cluster-wise aerosol optical index (aerosol optical depth at 500nm≈0.98-2.45), absorption (single scattering albedo ≈0.87-0.85; absorption aerosol optical depth ≈0.15-0.38 at 440nm; absorption Ångström exponent ≈1.43-1.57), and radiative impacts (atmospheric heating rate ≈1.4-3.6Kd -1 ) displayed consistency with the degree of BB. PM 2.5 during Extreme BB (EBB) was ≈4 times higher than during Low BB (LBB), whereas this factor was ≈2.5 for the magnitude of radiative effects. Severe haze (visibility≈4km) due to substantial BB loadings (BB to PM 2.5 ≈79%) with favorable meteorology can significantly impact the local-to-regional air quality and the, daily life of local inhabitants as well as become a respiratory health threat. Additionally, such enhancements in atmospheric heating could potentially influence the regional hydrological cycle and crop productivity over Chiang Mai in

  1. Carbonaceous aerosols and pollutants over Delhi urban environment: Temporal evolution, source apportionment and radiative forcing

    Energy Technology Data Exchange (ETDEWEB)

    Bisht, D.S. [Indian Institute of Tropical Meteorology, New Delhi (India); Dumka, U.C., E-mail: dumka@aries.res.in [Aryabhatta Research Institute of Observational Sciences, Nainital (India); Kaskaoutis, D.G. [School of Natural Sciences, Shiv Nadar University, Tehsil Dadri (India); Pipal, A.S. [Department of Chemistry, Savitribai Phule Pune University, Pune (India); Srivastava, A.K. [Indian Institute of Tropical Meteorology, New Delhi (India); Soni, V.K.; Attri, S.D.; Sateesh, M. [India Meteorology Department, Lodhi Road, New Delhi (India); Tiwari, S. [Indian Institute of Tropical Meteorology, New Delhi (India)

    2015-07-15

    Particulate matter (PM{sub 2.5}) samples were collected over Delhi, India during January to December 2012 and analysed for carbonaceous aerosols and inorganic ions (SO{sub 4}{sup 2−} and NO{sub 3}{sup −}) in order to examine variations in atmospheric chemistry, combustion sources and influence of long-range transport. The PM{sub 2.5} samples are measured (offline) via medium volume air samplers and analysed gravimetrically for carbonaceous (organic carbon, OC; elemental carbon, EC) aerosols and inorganic ions (SO{sub 4}{sup 2−} and NO{sub 3}{sup −}). Furthermore, continuous (online) measurements of PM{sub 2.5} (via Beta-attenuation analyser), black carbon (BC) mass concentration (via Magee scientific Aethalometer) and carbon monoxide (via CO-analyser) are carried out. PM{sub 2.5} (online) range from 18.2 to 500.6 μg m{sup −3} (annual mean of 124.6 ± 87.9 μg m{sup −3}) exhibiting higher night-time (129.4 μg m{sup −3}) than daytime (103.8 μg m{sup −3}) concentrations. The online concentrations are 38% and 28% lower than the offline during night and day, respectively. In general, larger night-time concentrations are found for the BC, OC, NO{sub 3}{sup −}and SO{sub 4}{sup 2−}, which are seasonally dependent with larger differences during late post-monsoon and winter. The high correlation (R{sup 2} = 0.74) between OC and EC along with the OC/EC of 7.09 (day time) and 4.55 (night-time), suggest significant influence of biomass-burning emissions (burning of wood and agricultural waste) as well as secondary organic aerosol formation during daytime. Concentrated weighted trajectory (CWT) analysis reveals that the potential sources for the carbonaceous aerosols and pollutants are local emissions within the urban environment and transported smoke from agricultural burning in northwest India during post-monsoon. BC radiative forcing estimates result in very high atmospheric heating rates (~ 1.8–2.0 K day{sup −1}) due to agricultural burning effects

  2. Carbonaceous aerosols and pollutants over Delhi urban environment: Temporal evolution, source apportionment and radiative forcing

    International Nuclear Information System (INIS)

    Bisht, D.S.; Dumka, U.C.; Kaskaoutis, D.G.; Pipal, A.S.; Srivastava, A.K.; Soni, V.K.; Attri, S.D.; Sateesh, M.; Tiwari, S.

    2015-01-01

    Particulate matter (PM 2.5 ) samples were collected over Delhi, India during January to December 2012 and analysed for carbonaceous aerosols and inorganic ions (SO 4 2− and NO 3 − ) in order to examine variations in atmospheric chemistry, combustion sources and influence of long-range transport. The PM 2.5 samples are measured (offline) via medium volume air samplers and analysed gravimetrically for carbonaceous (organic carbon, OC; elemental carbon, EC) aerosols and inorganic ions (SO 4 2− and NO 3 − ). Furthermore, continuous (online) measurements of PM 2.5 (via Beta-attenuation analyser), black carbon (BC) mass concentration (via Magee scientific Aethalometer) and carbon monoxide (via CO-analyser) are carried out. PM 2.5 (online) range from 18.2 to 500.6 μg m −3 (annual mean of 124.6 ± 87.9 μg m −3 ) exhibiting higher night-time (129.4 μg m −3 ) than daytime (103.8 μg m −3 ) concentrations. The online concentrations are 38% and 28% lower than the offline during night and day, respectively. In general, larger night-time concentrations are found for the BC, OC, NO 3 − and SO 4 2− , which are seasonally dependent with larger differences during late post-monsoon and winter. The high correlation (R 2 = 0.74) between OC and EC along with the OC/EC of 7.09 (day time) and 4.55 (night-time), suggest significant influence of biomass-burning emissions (burning of wood and agricultural waste) as well as secondary organic aerosol formation during daytime. Concentrated weighted trajectory (CWT) analysis reveals that the potential sources for the carbonaceous aerosols and pollutants are local emissions within the urban environment and transported smoke from agricultural burning in northwest India during post-monsoon. BC radiative forcing estimates result in very high atmospheric heating rates (~ 1.8–2.0 K day −1 ) due to agricultural burning effects during the 2012 post-monsoon season. - Highlights: • Very high PM 2.5 (> 200 µg m −3 ) levels

  3. Observations of black carbon aerosols characteristics over an urban environment: Radiative forcing and related implications.

    Science.gov (United States)

    Bibi, Samina; Alam, Khan; Chishtie, Farrukh; Bibi, Humera; Rahman, Said

    2017-12-15

    With observations of black carbon (BC) aerosol concentrations, optical and radiative properties were obtained over the urban city of Karachi during the period of March 2006-December 2008. BC concentrations were continuously measured using an Aethalometer, while optical and radiative properties were estimated through the Optical Properties of Aerosols and Clouds (OPAC) and Santa Barbra DISORT Atmospheric Radiative Transfer (SBDART) models, respectively. For the study period, the measured BC concentrations were higher during January, February and November, while lower during May, June, July and August. A maximum peak value was observed during January 2007 while the minimum value was observed during June 2006. The Short Wave (SW) BC Aerosol Radiative Forcing (ARF) both at Top of the Atmosphere (ToA) and within ATMOSphere (ATMOS) were positive during all the months, whereas negative SW BC ARF was found at the SurFaCe (SFC). Overall, SW BC ARF was higher during January, February and November, while relatively lower ARF was found during May, June, July and August. Conversely, the Long Wave (LW) BC ARF at ToA and SFC remained positive, whereas within ATMOS it shifted towards positive values (heating effect) during June-August. Finally, the net (SW+LW) BC ARF were found to be positive at ToA and in ATMOS, while negative at SFC. Moreover, a systematic increase in Atmospheric Heating Rate (AHR) was found during October to January. Additionally, we found highest correlation between Absorption Aerosol Optical Depth (AOD abs ) and SW BC ARF within ATMOS followed by SFC and ToA. Overall, the contribution of BC to the total ARF was found to greater than 84% for the whole observational period while contributing up to 93% during January 2007. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Evaluating the Sensitivity of the Mass-Based Particle Removal Calculations for HVAC Filters in ISO 16890 to Assumptions for Aerosol Distributions

    Directory of Open Access Journals (Sweden)

    Brent Stephens

    2018-02-01

    Full Text Available High efficiency particle air filters are increasingly being recommended for use in heating, ventilating, and air-conditioning (HVAC systems to improve indoor air quality (IAQ. ISO Standard 16890-2016 provides a methodology for approximating mass-based particle removal efficiencies for PM1, PM2.5, and PM10 using size-resolved removal efficiency measurements for 0.3 µm to 10 µm particles. Two historical volume distribution functions for ambient aerosol distributions are assumed to represent ambient air in urban and rural areas globally. The goals of this work are to: (i review the ambient aerosol distributions used in ISO 16890, (ii evaluate the sensitivity of the mass-based removal efficiency calculation procedures described in ISO 16890 to various assumptions that are related to indoor and outdoor aerosol distributions, and (iii recommend several modifications to the standard that can yield more realistic estimates of mass-based removal efficiencies for HVAC filters, and thus provide a more realistic representation of a greater number of building scenarios. The results demonstrate that knowing the PM mass removal efficiency estimated using ISO 16890 is not sufficient to predict the PM mass removal efficiency in all of the environments in which the filter might be used. The main reason for this insufficiency is that the assumptions for aerosol number and volume distributions can substantially impact the results, albeit with some exceptions.

  5. A case study of the impact of boundary layer aerosol size distribution on the surface UV irradiance

    Energy Technology Data Exchange (ETDEWEB)

    Kikas, U.; Reinhart, A. [University of Tartu (Estonia). Institute of Environmental Physics; Vaht, M. [Parnu Institute of Health Resort Treatment and Medical Rehabilitation (Estonia); Veismann, U. [Tartu Observatory (Estonia)

    2001-07-01

    The relationship between scattering characteristics of surface aerosol and surface UV irradiance was examined on the basis of the measurements carried out in June-August 1999 in Parnu, Estonia on the Eastern coast of the Baltic Sea (58{sup o}22'27 ''N, 24{sup o}30'43 ''E) The UV radiation spectra (300-34Onm) were measured with the Ocean Optics Inc. UV spectrometer PC 1000, the aerosol size distributions (3-1000nm) were measured with the electric aerosol spectrometer EAS. A case study was conducted for six sequential cloudless days, when the decrease of the surface UV irradiance was seemingly influenced by atmospheric aerosol. Aerosol radiative properties were calculated from the measured size distributions that represented the maritime polar (North Atlantic) and mixed maritime-continental air. The aerosol optical depths at 500nm for the North Atlantic air were estimated to be from 0.08 to 0. 13. The spectral aerosol optical depth agreed well with the Angstrom law, the Angstrom exponent ({alpha} varied from day to day between values of 0.52-0.90. Aerosol asymmetry factor at 300nm changed between values of 0.76 and 0.80, and was highly correlated with the mean radius of aerosol number distribution. The total aerosol UV scattering was mostly influenced by changes in aerosol with a diameter of 100-560nm. The aerosol scattering coefficients were positively correlated with the relative humidity of air. The ground aerosol properties were used for calculating the surface UV irradiance from the radiative transfer model of Bird and Riordan (J. Climate Appl. Meteorol. 25 (1986)). The calculated UV irradiances correlated quite well with the measured ones, showing that the use of ground aerosol data for radiative transfer calculations turned out reasonable results. However, ignoring the changes in the aerosol vertical distribution resulted in overestimation of aerosol optical depth on hazy days. (author)

  6. Scanning vertical distributions of typical aerosols along the Yangtze River using elastic lidar.

    Science.gov (United States)

    Fan, Shidong; Liu, Cheng; Xie, Zhouqing; Dong, Yunsheng; Hu, Qihou; Fan, Guangqiang; Chen, Zhengyi; Zhang, Tianshu; Duan, Jingbo; Zhang, Pengfei; Liu, Jianguo

    2018-07-01

    In recent years, China has experienced heavy air pollution, especially haze caused by particulate matter (PM). The compositions, horizontal distributions, transport, and chemical formation mechanisms of PM and its precursors have been widely investigated in China based on near-ground measurements. However, the understanding of the distributions and physical and chemical processes of PM in the vertical direction remains limited. In this study, an elastic lidar was employed to investigate the vertical profiles of aerosols along the Yangtze River during the Yangtze River Campaign of winter 2015. Some typical aerosols were identified and some events were analyzed in three cases. Dust aerosols can be transported from the Gobi Desert to the Yangtze River basin across a long distance at both low and high altitudes in early December. The transport route was perpendicular to the ship track, suggesting that the dust aerosols may have affected a large area. Moreover, during transport, some dust was also affected by the areas below its transport route since some anthropogenic pollutants were mixed with the dust and changed some of its optical properties. Biomass-burning aerosols covering a distant range along the Yangtze River were identified. This result directly shows the impact areas of biomass-burning aerosols in some agricultural fields. Some directly emitted aerosol plumes were observed, and direct effects of such plumes were limited both temporally and spatially. In addition, an aerosol plume with very low linear depolarization ratios, probably formed through secondary processes, was also observed. These results can help us better understand aerosols in large spatial scales in China and can be useful to regional haze studies. Copyright © 2018. Published by Elsevier B.V.

  7. C1-C2 alkyl aminiums in urban aerosols: Insights from ambient and fuel combustion emission measurements in the Yangtze River Delta region of China

    International Nuclear Information System (INIS)

    Shen, Wenchao; Ren, Lili; Zhao, Yi; Zhou, Luyu; Dai, Liang; Ge, Xinlei; Kong, Shaofei; Yan, Qin; Xu, Honghui; Jiang, Yujun; He, Jun; Chen, Mindong; Yu, Huan

    2017-01-01

    We measured low molar-mass alkyl aminiums (methylaminium, dimethylaminium, ethylaminium and diethylaminium) in urban aerosols in the Yangtze River Delta region of eastern China in August 2014 and from November 2015 to May 2016. After examining artifact formation on sample filters, methylaminium, dimethylaminium and ethylaminium concentrations were quantified. The three C1-C2 aminiums exhibited a unimodal size distribution that maximized between 0.56 and 1.0 μm. Their concentrations in PM 2.5 were 5.7 ± 3.2 ng m −3 , 7.9 ± 5.4 ng m −3 and 20.3 ± 16.6 ng m −3 , respectively, with higher concentrations during the daytime and in warm seasons. On new particle growth days, amine uptake to particles larger than 56 nm was barely enhanced. The molar ratios of individual aminium/NH 4 + in PM 2.5 were on the order of 10 −4 and 10 −3 . Aminiums were thus far less to out-compete ammonium (NH 4 + ) in neutralizing acidic species in particle sizes down to 56 nm. Abundant nitrate (NO 3 − /SO 4 2− molar ratio = ∼3) and its correlation to methylaminium and ethylaminium implied that nitrate might be more important aminium salt than sulfate in urban aerosols of this area. Direct measurement of particle-phase amine emission from coal and biomass burning showed that coal burning is an important atmospheric amine source, considering coal burning is top-ranked particulate matter source in China. - Highlights: • Aminium concentration showed seasonal and diurnal variations in urban aerosols of our area. • Nitrate was more important aminium salt than sulfate in urban aerosols of our area. • Particle-phase amine emission from coal burning is an important atmospheric amine source. • Amine uptake to particles larger than 56 nm was barely enhanced on new particle growth events. • Aminiums cannot out-compete ammonium in neutralizing acidic species in urban aerosols with particle sizes down to 56 nm. - Aminiums cannot out-compete ammonium in

  8. Volatility measurement of atmospheric submicron aerosols in an urban atmosphere in southern China

    Directory of Open Access Journals (Sweden)

    L.-M. Cao

    2018-02-01

    Full Text Available Aerosol pollution has been a very serious environmental problem in China for many years. The volatility of aerosols can affect the distribution of compounds in the gas and aerosol phases, the atmospheric fates of the corresponding components, and the measurement of the concentration of aerosols. Compared to the characterization of chemical composition, few studies have focused on the volatility of aerosols in China. In this study, a thermodenuder aerosol mass spectrometer (TD-AMS system was deployed to study the volatility of non-refractory submicron particulate matter (PM1 species during winter in Shenzhen. To our knowledge, this paper is the first report of the volatilities of aerosol chemical components based on a TD-AMS system in China. The average PM1 mass concentration during the experiment was 42.7±20.1 µg m−3, with organic aerosol (OA being the most abundant component (43.2 % of the total mass. The volatility of chemical species measured by the AMS varied, with nitrate showing the highest volatility, with a mass fraction remaining (MFR of 0.57 at 50 °C. Organics showed semi-volatile characteristics (the MFR was 0.88 at 50 °C, and the volatility had a relatively linear correlation with the TD temperature (from the ambient temperature to 200 °C, with an evaporation rate of 0.45 % °C−1. Five subtypes of OA were resolved from total OA using positive matrix factorization (PMF for data obtained under both ambient temperature and high temperatures through the TD, including a hydrocarbon-like OA (HOA, accounting for 13.5 %, a cooking OA (COA, 20.6 %, a biomass-burning OA (BBOA, 8.9 %, and two oxygenated OAs (OOAs: a less-oxidized OOA (LO-OOA, 39.1 % and a more-oxidized OOA (MO-OOA, 17.9 %. Different OA factors presented different volatilities, and the volatility sequence of the OA factors at 50 °C was HOA (MFR of 0.56  >  LO-OOA (0.70  >  COA (0.85  ≈  BBOA (0.87

  9. Rapid Measurements of Aerosol Size Distribution and Hygroscopic Growth via Image Processing with a Fast Integrated Mobility Spectrometer (FIMS)

    Science.gov (United States)

    Wang, Y.; Pinterich, T.; Spielman, S. R.; Hering, S. V.; Wang, J.

    2017-12-01

    Aerosol size distribution and hygroscopicity are among key parameters in determining the impact of atmospheric aerosols on global radiation and climate change. In situ submicron aerosol size distribution measurements commonly involve a scanning mobility particle sizer (SMPS). The SMPS scanning time is in the scale of minutes, which is often too slow to capture the variation of aerosol size distribution, such as for aerosols formed via nucleation processes or measurements onboard research aircraft. To solve this problem, a Fast Integrated Mobility Spectrometer (FIMS) based on image processing was developed for rapid measurements of aerosol size distributions from 10 to 500 nm. The FIMS consists of a parallel plate classifier, a condenser, and a CCD detector array. Inside the classifier an electric field separates charged aerosols based on electrical mobilities. Upon exiting the classifier, the aerosols pass through a three stage growth channel (Pinterich et al. 2017; Spielman et al. 2017), where aerosols as small as 7 nm are enlarged to above 1 μm through water or heptanol condensation. Finally, the grown aerosols are illuminated by a laser sheet and imaged onto a CCD array. The images provide both aerosol concentration and position, which directly relate to the aerosol size distribution. By this simultaneous measurement of aerosols with different sizes, the FIMS provides aerosol size spectra nearly 100 times faster than the SMPS. Recent deployment onboard research aircraft demonstrated that the FIMS is capable of measuring aerosol size distributions in 1s (Figure), thereby offering a great advantage in applications requiring high time resolution (Wang et al. 2016). In addition, the coupling of the FIMS with other conventional aerosol instruments provides orders of magnitude more rapid characterization of aerosol optical and microphysical properties. For example, the combination of a differential mobility analyzer, a relative humidity control unit, and a FIMS was

  10. Selection of City Distribution Locations in Urbanized Areas

    NARCIS (Netherlands)

    Bu, L.; Van Duin, J.H.R.; Wiegmans, B.; Luo, Z.; Yin, C.

    2012-01-01

    This paper aims to apply a preference method for selecting optimal city distribution reloading locations in urbanized areas. The focus in the optimization is on trucks entering the urbanized area where the truck can choose between at least two locations with similar distances determined by a

  11. Changes in column aerosol optical properties during extreme haze-fog episodes in January 2013 over urban Beijing

    International Nuclear Information System (INIS)

    Yu, Xingna; Kumar, K. Raghavendra; Lü, Rui; Ma, Jia

    2016-01-01

    Several dense haze-fog (HF) episodes were occurred in the North China Plain (NCP), especially over Beijing in January 2013 characterized by a long duration, a large influential region, and an extremely high PM 2.5 values (>500 μg m −3 ). In this study, we present the characteristics of aerosol optical properties and radiative forcing using Cimel sun-sky radiometer measurements during HF and no haze-fog (NHF) episodes occurred over Beijing during 1–31 January, 2013. The respective maximum values of daily mean aerosol optical depth at 440 nm (AOD 440 ) were observed to be 1.21, 1.43, 1.52, and 2.21 occurred on 12, 14 19, and 28 January. It was found that the Ångström exponent (AE) values were almost higher than 1.0 during all the days with its maximum on 26 January (1.53), suggests the dominance of fine-mode particles. The maximum (minimum) aerosol volume size distributions occurred during dense HF (NHF) days with larger particle volumes of fine-mode. The single scattering albedo, asymmetry parameter, and complex refractive index values during HF events suggest the abundance of fine-mode particles from anthropogenic (absorbing) activities mixed with scattering dust particles. The average shortwave direct aerosol radiative forcing (DARF) values at the bottom-of-atmosphere (BOA) during HF and NHF days were estimated to be 112.29 ± 42.18 W m −2 and −58.61 ± 13.09 W m −2 , while at the top-of-atmosphere (TOA) the forcing values were −45.78 ± 22.17 W m −2 and −18.64 ± 5.84 W m −2 , with the corresponding heating rate of 1.61 ± 0.48 K day −1 and 1.12 ± 0.31 K day −1 , respectively. The DARF values retrieved from the AERONET were in good agreement with the SBDART computed both at the TOA (r = 0.95) and the BOA (r = 0.97) over Beijing in January 2013. - Highlights: • Aerosol optical properties were reported during dense haze-fog (HF) episode. • High AE during HF episode observed dominance of fine mode

  12. The Spatial and Temporal Distributions of Absorbing Aerosols over East Asia

    Directory of Open Access Journals (Sweden)

    Litai Kang

    2017-10-01

    Full Text Available Absorbing aerosols can strongly absorb solar radiation and have a profound impact on the global and regional climate. Black carbon (BC, organic carbon (OC and dust are three major types of absorbing aerosols. In order to deepen the overall understanding of absorbing aerosols over East Asia and provide a basis for further investigation of its role in enhanced warming in drylands, the spatial-temporal distribution of absorbing aerosols over East Asia for the period of 2005–2016 was investigated based on the Ozone Monitoring Instrument (OMI satellite retrievals. Overall, high values of Aerosol Absorption Optical Depth (AAOD mainly distribute near dust sources as well as BC and OC sources. AAOD reaches its maximum during spring over East Asia as a result of dust activity and biomass burning. Single-scattering albedo (SSA is comparatively high (>0.96 in the most part of East Asia in the summer, indicating the dominance of aerosol scattering. Hyper-arid regions have the highest Aerosol Optical Depth (AOD and AAOD among the five climatic regions, with springtime values up to 0.72 and 0.04, respectively. Humid and sub-humid regions have relatively high AOD and AAOD during the spring and winter and the highest SSA during the summer. AAOD in some areas shows significant upward trends, which is likely due to the increase of BC and OC emission. SSA shows overall downward trends, indicating the enhancement of the aerosol absorption. Analysis of emission inventory and dust index data shows that BC and OC emissions mainly come from the humid regions, while dust sources mainly distribute in drylands.

  13. Persistence of urban organic aerosols composition: Decoding their structural complexity and seasonal variability.

    Science.gov (United States)

    Matos, João T V; Duarte, Regina M B O; Lopes, Sónia P; Silva, Artur M S; Duarte, Armando C

    2017-12-01

    Organic Aerosols (OAs) are typically defined as highly complex matrices whose composition changes in time and space. Focusing on time vector, this work uses two-dimensional nuclear magnetic resonance (2D NMR) techniques to examine the structural features of water-soluble (WSOM) and alkaline-soluble organic matter (ASOM) sequentially extracted from fine atmospheric aerosols collected in an urban setting during cold and warm seasons. This study reveals molecular signatures not previously decoded in NMR-related studies of OAs as meaningful source markers. Although the ASOM is less hydrophilic and structurally diverse than its WSOM counterpart, both fractions feature a core with heteroatom-rich branched aliphatics from both primary (natural and anthropogenic) and secondary origin, aromatic secondary organics originated from anthropogenic aromatic precursors, as well as primary saccharides and amino sugar derivatives from biogenic emissions. These common structures represent those 2D NMR spectral signatures that are present in both seasons and can thus be seen as an "annual background" profile of the structural composition of OAs at the urban location. Lignin-derived structures, nitroaromatics, disaccharides, and anhydrosaccharides signatures were also identified in the WSOM samples only from periods identified as smoke impacted, which reflects the influence of biomass-burning sources. The NMR dataset on the H-C molecules backbone was also used to propose a semi-quantitative structural model of urban WSOM, which will aid efforts for more realistic studies relating the chemical properties of OAs with their atmospheric behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Aerosol particles generated by diesel-powered school buses at urban schools as a source of children’s exposure

    Science.gov (United States)

    Hochstetler, Heather A.; Yermakov, Mikhail; Reponen, Tiina; Ryan, Patrick H.; Grinshpun, Sergey A.

    2015-01-01

    Various heath effects in children have been associated with exposure to traffic-related particulate matter (PM), including emissions from school buses. In this study, the indoor and outdoor aerosol at four urban elementary schools serviced by diesel-powered school buses was characterized with respect to the particle number concentrations and size distributions as well as the PM2.5 mass concentrations and elemental compositions. It was determined that the presence of school buses significantly affected the outdoor particle size distribution, specifically in the ultrafine fraction. The time-weighted average of the total number concentration measured outside the schools was significantly associated with the bus and the car counts. The concentration increase was consistently observed during the morning drop-off hours and in most of the days during the afternoon pick-up period (although at a lower degree). Outdoor PM2.5 mass concentrations measured at schools ranged from 3.8 to 27.6 µg m−3. The school with the highest number of operating buses exhibited the highest average PM2.5 mass concentration. The outdoor mass concentrations of elemental carbon (EC) and organic carbon (OC) were also highest at the school with the greatest number of buses. Most (47/55) correlations between traffic-related elements identified in the outdoor PM2.5 were significant with elements identified in the indoor PM2.5. Significant associations were observed between indoor and outdoor aerosols for EC, EC/OC, and the total particle number concentration. Day-to-day and school-to-school variations in Indoor/Outdoor (I/O) ratios were related to the observed differences in opening windows and doors, which enhanced the particle penetration, as well as indoor activities at schools. Overall, the results on I/O ratio obtained in this study reflect the sizes of particles emitted by diesel-powered school bus engines (primarily, an ultrafine fraction capable of penetrating indoors). PMID:25904818

  15. Aerosol particles generated by diesel-powered school buses at urban schools as a source of children's exposure.

    Science.gov (United States)

    Hochstetler, Heather A; Yermakov, Mikhail; Reponen, Tiina; Ryan, Patrick H; Grinshpun, Sergey A

    2011-03-01

    Various heath effects in children have been associated with exposure to traffic-related particulate matter (PM), including emissions from school buses. In this study, the indoor and outdoor aerosol at four urban elementary schools serviced by diesel-powered school buses was characterized with respect to the particle number concentrations and size distributions as well as the PM2.5 mass concentrations and elemental compositions. It was determined that the presence of school buses significantly affected the outdoor particle size distribution, specifically in the ultrafine fraction. The time-weighted average of the total number concentration measured outside the schools was significantly associated with the bus and the car counts. The concentration increase was consistently observed during the morning drop-off hours and in most of the days during the afternoon pick-up period (although at a lower degree). Outdoor PM2.5 mass concentrations measured at schools ranged from 3.8 to 27.6 µg m -3 . The school with the highest number of operating buses exhibited the highest average PM2.5 mass concentration. The outdoor mass concentrations of elemental carbon (EC) and organic carbon (OC) were also highest at the school with the greatest number of buses. Most (47/55) correlations between traffic-related elements identified in the outdoor PM2.5 were significant with elements identified in the indoor PM2.5. Significant associations were observed between indoor and outdoor aerosols for EC, EC/OC, and the total particle number concentration. Day-to-day and school-to-school variations in Indoor/Outdoor (I/O) ratios were related to the observed differences in opening windows and doors, which enhanced the particle penetration, as well as indoor activities at schools. Overall, the results on I/O ratio obtained in this study reflect the sizes of particles emitted by diesel-powered school bus engines (primarily, an ultrafine fraction capable of penetrating indoors).

  16. Molecular marker study of extractable organic matter in aerosols from urban areas of China

    Science.gov (United States)

    Simoneit, Bernd R. T.; Sheng, Guoying; Chen, Xiaojing; Fu, Jiamo; Zhang, Jian; Xu, Yuping

    The solvent-extractable compounds (lipids) of aerosol samples, which were collected from a western suburb of Beijing, in the city of Guiyang and on the outskirts of Guangzhou, P.R. China, using a standard high volume air sampler, were investigated to determine the distributions of homologous compounds and biomarkers. These preliminary results show that all samples contain aliphatic hydrocarbons including n-alkanes, steranes and triterpanes, derived from both biogenic sources (vascular plant wax input) and fossil fuel contamination (coal, crude oil, etc.). Polynuclear aromatic hydrocarbons, which are considered to be combustion products from fossil fuels such as petroleum and, especially in this case, coal burning, are also widely distributed in all samples. Oxygenated compounds (e.g. alkanoic acids, alkanones and alkanols) are present as major fractions and are derived from mainly natural sources. Furthermore, some compositional differences are observed for the organic compounds in samples from different heights above ground. This is interpreted to be due to dilution at higher levels of locally generated aerosol with upper air aerosol transported over longer distances.

  17. Biomass burning contributions to urban aerosols in a coastal Mediterranean city.

    Science.gov (United States)

    Reche, C; Viana, M; Amato, F; Alastuey, A; Moreno, T; Hillamo, R; Teinilä, K; Saarnio, K; Seco, R; Peñuelas, J; Mohr, C; Prévôt, A S H; Querol, X

    2012-06-15

    Mean annual biomass burning contributions to the bulk particulate matter (PM(X)) load were quantified in a southern-European urban environment (Barcelona, Spain) with special attention to typical Mediterranean winter and summer conditions. In spite of the complexity of the local air pollution cocktail and the expected low contribution of biomass burning emissions to PM levels in Southern Europe, the impact of these emissions was detected at an urban background site by means of tracers such as levoglucosan, K(+) and organic carbon (OC). The significant correlation between levoglucosan and OC (r(2)=0.77) and K(+) (r(2)=0.65), as well as a marked day/night variability of the levoglucosan levels and levoglucosan/OC ratios was indicative of the contribution from regional scale biomass burning emissions during night-time transported by land breezes. In addition, on specific days (21-22 March), the contribution from long-range transported biomass burning aerosols was detected. Quantification of the contribution of biomass burning aerosols to PM levels on an annual basis was possible by means of the Multilinear Engine (ME). Biomass burning emissions accounted for 3% of PM(10) and PM(2.5) (annual mean), while this percentage increased up to 5% of PM(1). During the winter period, regional-scale biomass burning emissions (agricultural waste burning) were estimated to contribute with 7±4% of PM(2.5) aerosols during night-time (period when emissions were clearly detected). Long-range transported biomass burning aerosols (possibly from forest fires and/or agricultural waste burning) accounted for 5±2% of PM(2.5) during specific episodes. Annually, biomass burning emissions accounted for 19%-21% of OC levels in PM(10), PM(2.5) and PM(1). The contribution of this source to K(+) ranged between 48% for PM(10) and 97% for PM(1) (annual mean). Results for K(+) from biomass burning evidenced that this tracer is mostly emitted in the fine fraction, and thus coarse K(+) could not be

  18. Detailed Comparison of OC/EC Aerosol at an Urban and a Rural Czech Background Site during Summer and Winter

    Czech Academy of Sciences Publication Activity Database

    Vodička, Petr; Schwarz, Jaroslav; Cusack, Michael; Ždímal, Vladimír

    518-519, JUN 15 (2015), s. 424-433 ISSN 0048-9697 R&D Projects: GA ČR GAP209/11/1342 Institutional support: RVO:67985858 Keywords : carbonaceous aerosol * urban and rural background * organic carbon fractions Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.976, year: 2015

  19. Simultaneous aerosol size distribution and turbidity measurements over St. Louis during METROMEX 1975

    International Nuclear Information System (INIS)

    Laulainen, N.S.; Alkezweeny, A.J.; Thorp, J.M.

    1978-01-01

    An experiment designed to measure aerosol size distributions and turbidity simultaneously over a metropolitan area is described. The particle volume size distributions measured in the city plume are found to be bimodal, with the total particle volume in the fine or submicron mode decreasing dramatically above the inversion. Aerosol extinction coefficients derived from sunphotometer optical depth measurements at four wavelengths are compared to those calculated from the measured size distributions using Mie theory with several different particle refractive indices. The accuracy of the experimental method for determining the aerosol extinction coefficient prevented any meaningful choice of the real part of particle refractive index between 1.5--1.6 and an imaginary part between 0 and -0.1i. Improvements to this type of experiment are discussed

  20. Geochemistry of aerosols from an urban site, Varanasi, in the Eastern Indo-Gangetic Plain

    Science.gov (United States)

    Ram, Kirpa; Norra, Stefan; Zirzov, Felix; Singh, Sunita; Mehra, Manisha; Nanad Tripathi, Sachichida

    2016-04-01

    PM2.5 aerosol samples were collected from an urban site, Varanasi, in the eastern Indo-Gangetic Plain on weekly basis during 19 March to 29 May 2015 (n=12), along with daily samples (n=8) during 11 to 18 March 2015 to study the geochemical and morphological features of aerosols. Samples were collected with a low volume sampler (Leckel GmbH, Germany) on the terrace of the Institute of Environment and Sustainable Development building, located in the Banaras Hindu University campus in the southern part of the city. Samples were analyzed for element concentration by Inductively Coupled Plasma Mass Spectrometry and particle morphology by Scanning Electron Microscope. PM2.5 concentration ranged between 22.3 and 70.5 μgm-3 in daily samples, whereas those varied between 52.0 and 106 μgm-3 in weekly samples. Lead, potassium, aluminum, zinc and iron have conspicuously higher concentrations with Pb concentration exceeding above the annual limit of 50 ngm-3 in four samples. First results show a trend of corresponding concentrations of chemical elements originated from anthropogenic and geogenic sources. The biogenic particles are a minor fraction of the total particulate aerosols. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) back trajectory analysis of air parcels indicate that the air mass for the low loaded days originate from eastern directions including the region of the gulf of Bengal, where as high aerosols concentrations in cases of air masses arriving from north-western direction transporting the air pollutants from the Gangetic Plain towards Varanasi. Black carbon (BC) concentration, measured using an microaethalometer (AE-51), exhibit a strong variability (4.4 to 8.4 μg m-3) in the University campus which are ˜20-40% lower than those measured in the Varanasi city. The carbon content was found to be high with soot particles constituting the largest part in these samples and exist as single particle as well as attachment to other particles

  1. Scattering and absorption characteristics of aerosols at an urban megacity over IGB: Implications to radiative forcing

    Science.gov (United States)

    Srivastava, A. K.; Bisht, D. S.; Singh, Sachchidanand; Kishore, N.; Soni, V. K.; Singh, Siddhartha; Tiwari, S.

    2018-06-01

    Aerosol scattering and absorption characteristics were investigated at an urban megacity Delhi in the western Indo-Gangetic Basin (IGB) during the period from October 2011 to September 2012 using different in-situ measurements. The scattering coefficient (σsp at 550 nm) varied between 71 and 3014 Mm-1 (mean 710 ± 615 Mm-1) during the entire study period, which was about ten times higher than the absorption coefficient (σabs at 550 nm 67 ± 40 Mm-1). Seasonally, σsp and σabs were substantially higher during the winter/post-monsoon periods, which also gave rise to single scattering albedo (SSA) by 5%. The magnitude of SSA (at 550 nm) varied between 0.81 and 0.94 (mean: 0.89 ± 0.05). Further, the magnitude of scattering Ångström exponent (SAE) and back-scattering Ångström exponent (BAE) showed a wide range from -1.20 to 1.57 and -1.13 to 0.87, respectively which suggests large variability in aerosol sizes and emission sources. Relatively higher aerosol backscatter fraction (b at 550 nm) during the monsoon (0.25 ± 0.10) suggests more inhomogeneous scattering, associated with the coarser dust particles. However, lower value of b during winter (0.13 ± 0.02) is associated with more isotropic scattering due to dominance of smaller size particles. This is further confirmed with the estimated asymmetry parameter (AP at 550 nm), which exhibits opposite trend with b. The aerosol optical parameters were used in a radiative transfer model to estimate aerosol radiative forcing. A mean radiative forcing of -61 ± 22 W m-2 (ranging from -111 to -40 W m-2) was observed at the surface and 42 ± 24 W m-2 (ranging from 18 to 87 W m-2) into the atmosphere, which can give rise to the mean atmospheric heating rate of 1.18 K day-1.

  2. Atmospheric aerosol sampling campaign in Budapest and K-puszta. Part 1. Elemental concentrations and size distributions

    International Nuclear Information System (INIS)

    Dobos, E.; Borbely-Kiss, I.; Kertesz, Zs.; Szabo, Gy.; Salma, I.

    2004-01-01

    Complete text of publication follows. Atmospheric aerosol samples were collected in a sampling campaign from 24 July to 1 Au- gust, 2003 in Hungary. The sampling were performed in two places simultaneously: in Budapest (urban site) and K-puszta (remote area). Two PIXE International 7-stage cascade impactors were used for aerosol sampling with 24 hours duration. These impactors separate the aerosol into 7 size ranges. The elemental concentrations of the samples were obtained by proton-induced X-ray Emission (PIXE) analysis. Size distributions of S, Si, Ca, W, Zn, Pb and Fe elements were investigated in K-puszta and in Budapest. Average rates (shown in Table 1) of the elemental concentrations was calculated for each stage (in %) from the obtained distributions. The elements can be grouped into two parts on the basis of these data. The majority of the particle containing Fe, Si, Ca, (Ti) are in the 2-8 μm size range (first group). These soil origin elements were found usually in higher concentration in Budapest than in K-puszta (Fig.1.). The second group consisted of S, Pb and (W). The majority of these elements was found in the 0.25-1 μm size range and was much higher in Budapest than in K-puszta. W was measured only in samples collected in Budapest. Zn has uniform distribution in Budapest and does not belong to the above mentioned groups. This work was supported by the National Research and Development Program (NRDP 3/005/2001). (author)

  3. Integrated infomobility services for urban freight distribution

    NARCIS (Netherlands)

    Zuccotti, S.; Corongiu, A.; Forkert, S.; Nasr, A.; Quak, H.; Torres, C.

    2011-01-01

    City logistics is one of the causes of today's road congestion in our cities, but at the same time its efficiency is affected by the traffic problems. The driving behaviour and mission strategies used by vans and lorries operating in urban areas usually does not exploit modern infomobility

  4. An effective inversion algorithm for retrieving bimodal aerosol particle size distribution from spectral extinction data

    Science.gov (United States)

    He, Zhenzong; Qi, Hong; Yao, Yuchen; Ruan, Liming

    2014-12-01

    The Ant Colony Optimization algorithm based on the probability density function (PDF-ACO) is applied to estimate the bimodal aerosol particle size distribution (PSD). The direct problem is solved by the modified Anomalous Diffraction Approximation (ADA, as an approximation for optically large and soft spheres, i.e., χ⪢1 and |m-1|⪡1) and the Beer-Lambert law. First, a popular bimodal aerosol PSD and three other bimodal PSDs are retrieved in the dependent model by the multi-wavelength extinction technique. All the results reveal that the PDF-ACO algorithm can be used as an effective technique to investigate the bimodal PSD. Then, the Johnson's SB (J-SB) function and the modified beta (M-β) function are employed as the general distribution function to retrieve the bimodal PSDs under the independent model. Finally, the J-SB and M-β functions are applied to recover actual measurement aerosol PSDs over Beijing and Shanghai obtained from the aerosol robotic network (AERONET). The numerical simulation and experimental results demonstrate that these two general functions, especially the J-SB function, can be used as a versatile distribution function to retrieve the bimodal aerosol PSD when no priori information about the PSD is available.

  5. Chemical composition, source, and process of urban aerosols during winter haze formation in Northeast China.

    Science.gov (United States)

    Zhang, Jian; Liu, Lei; Wang, Yuanyuan; Ren, Yong; Wang, Xin; Shi, Zongbo; Zhang, Daizhou; Che, Huizheng; Zhao, Hujia; Liu, Yanfei; Niu, Hongya; Chen, Jianmin; Zhang, Xiaoye; Lingaswamy, A P; Wang, Zifa; Li, Weijun

    2017-12-01

    The characteristics of aerosol particles have been poorly evaluated even though haze episodes frequently occur in winter in Northeast China. OC/EC analysis, ion chromatography, and transmission electron microscopy (TEM) were used to investigate the organic carbon (OC) and elemental carbon (EC), and soluble ions in PM 2.5 and the mixing state of individual particles during a severe wintertime haze episode in Northeast China. The organic matter (OM), NH 4 + , SO 4 2- , and NO 3 - concentrations in PM 2.5 were 89.5 μg/m 3 , 24.2 μg/m 3 , 28.1 μg/m 3 , and 32.8 μg/m 3 on the haze days, respectively. TEM observations further showed that over 80% of the haze particles contained primary organic aerosols (POAs). Based on a comparison of the data obtained during the haze formation, we generate the following synthetic model of the process: (1) Stable synoptic meteorological conditions drove the haze formation. (2) The early stage of haze formation (light or moderate haze) was mainly caused by the enrichment of POAs from coal burning for household heating and cooking. (3) High levels of secondary organic aerosols (SOAs), sulfates, and nitrates formation via heterogeneous reactions together with POAs accumulation promoted to the evolution from light or moderate to severe haze. Compared to the severe haze episodes over the North China Plain, the PM 2.5 in Northeast China analyzed in the present study contained similar sulfate, higher SOA, and lower nitrate contents. Our results suggest that most of the POAs and secondary particles were likely related to emissions from coal-burning residential stoves in rural outskirts and small boilers in urban areas. The inefficient burning of coal for household heating and cooking should be monitored during wintertime in Northeast China. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Pan-Arctic aerosol number size distributions: seasonality and transport patterns

    Science.gov (United States)

    Freud, Eyal; Krejci, Radovan; Tunved, Peter; Leaitch, Richard; Nguyen, Quynh T.; Massling, Andreas; Skov, Henrik; Barrie, Leonard

    2017-07-01

    The Arctic environment has an amplified response to global climatic change. It is sensitive to human activities that mostly take place elsewhere. For this study, a multi-year set of observed aerosol number size distributions in the diameter range of 10 to 500 nm from five sites around the Arctic Ocean (Alert, Villum Research Station - Station Nord, Zeppelin, Tiksi and Barrow) was assembled and analysed.A cluster analysis of the aerosol number size distributions revealed four distinct distributions. Together with Lagrangian air parcel back-trajectories, they were used to link the observed aerosol number size distributions with a variety of transport regimes. This analysis yields insight into aerosol dynamics, transport and removal processes, on both an intra- and an inter-monthly scale. For instance, the relative occurrence of aerosol number size distributions that indicate new particle formation (NPF) event is near zero during the dark months, increases gradually to ˜ 40 % from spring to summer, and then collapses in autumn. Also, the likelihood of Arctic haze aerosols is minimal in summer and peaks in April at all sites.The residence time of accumulation-mode particles in the Arctic troposphere is typically long enough to allow tracking them back to their source regions. Air flow that passes at low altitude over central Siberia and western Russia is associated with relatively high concentrations of accumulation-mode particles (Nacc) at all five sites - often above 150 cm-3. There are also indications of air descending into the Arctic boundary layer after transport from lower latitudes.The analysis of the back-trajectories together with the meteorological fields along them indicates that the main driver of the Arctic annual cycle of Nacc, on the larger scale, is when atmospheric transport covers the source regions for these particles in the 10-day period preceding the observations in the Arctic. The scavenging of these particles by precipitation is shown to be

  7. Radiocarbon variability of fatty acids in semi-urban aerosol samples

    International Nuclear Information System (INIS)

    Matsumoto, Kohei; Uchida, Masao; Kawamura, Kimitaka; Shibata, Yasuyuki; Morita, Masatoshi

    2004-01-01

    We analyzed radiocarbon and the stable carbon isotope ratio for individual monocarboxylic (fatty) acids in an aerosol sample (QFF 2138) and compared the results with data of the aerosol sample taken in another year. The fatty acid concentration distribution of aerosol sample QFF 2138 showed a bimodal pattern with maxima at C 16 and C 26 . Stable carbon isotope ratios of the fatty acids ranged from -30.8 per mille to -23.0 per mille which indicates the animal and/or marine algae origins for C 16 -C 19 fatty acids and mainly terrestrial C 3 plant origins for C >20 fatty acids. Δ 14 C values for fatty acids ranged from -89.7 per mille to +83.5 per mille. Compared with QFF1969, we found that the Δ 14 C values of fatty acids exhibited a wide diversity and Δ 14 C values for each fatty acid in QFF 2138 were largely different from those of QFF 1969

  8. Algorithm of Data Reduce in Determination of Aerosol Particle Size Distribution at Damps/C

    International Nuclear Information System (INIS)

    Muhammad-Priyatna; Otto-Pribadi-Ruslanto

    2001-01-01

    The analysis had to do for algorithm of data reduction on Damps/C (Differential Mobility Particle Sizer with Condensation Particle Counter) system, this is for determine aerosol particle size distribution with range 0,01 μm to 1 μm in diameter. Damps/C (Differential Mobility Particle Sizer with Condensation Particle Counter) system contents are software and hardware. The hardware used determine of mobilities of aerosol particle and so the software used determine aerosol particle size distribution in diameter. The mobilities and diameter particle had connection in the electricity field. That is basic program for reduction of data and particle size conversion from particle mobility become particle diameter. The analysis to get transfer function value, Ω, is 0.5. The data reduction program to do conversation mobility basis become diameter basis with number efficiency correction, transfer function value, and poly charge particle. (author)

  9. Simulating SAL formation and aerosol size distribution during SAMUM-I

    KAUST Repository

    Khan, Basit Ali

    2015-04-01

    To understand the formation mechanisms of Saharan Air Layer (SAL), we combine model simulations and dust observations collected during the first stage of the Saharan Mineral Dust Experiment (SAMUM-I), which sampled dust events that extended from Morocco to Portugal, and investigated the spatial distribution and the microphysical, optical, chemical, and radiative properties of Saharan mineral dust. We employed the Weather Research Forecast model coupled with the Chemistry/Aerosol module (WRF-Chem) to reproduce the meteorological environment and spatial and size distributions of dust. The experimental domain covers northwest Africa including the southern Sahara, Morocco and part of the Atlantic Ocean with 5 km horizontal grid spacing and 51 vertical layers. The experiments were run from 20 May to 9 June 2006, covering the period of most intensive dust outbreaks. Comparisons of model results with available airborne and ground-based observations show that WRF-Chem reproduces observed meteorological fields as well as aerosol spatial distribution across the entire region and along the airplane\\'s tracks. We evaluated several aerosol uplift processes and found that orographic lifting, aerosol transport through the land/sea interface with steep gradients of meteorological characteristics, and interaction of sea breezes with the continental outflow are key mechanisms that form a surface-detached aerosol plume over the ocean. Comparisons of simulated dust size distributions with airplane and ground-based observations are generally good, but suggest that more detailed treatment of microphysics in the model is required to capture the full-scale effect of large aerosol particles.

  10. Aircraft observations of aerosols O{sub 3} and NO{sub y} in a nighttime urban plume

    Energy Technology Data Exchange (ETDEWEB)

    Berkowitz, C.M.; Zaveri, R.A.; Xindi Bian; Shiyuan Zhong; Disselkamp, R.S.; Laulainen, N.S.; Chapman, E.G. [Pacific Northwest National Lab., Richland, WA (United States)

    2001-05-01

    Nighttime measurements of aerosol surface area, O{sub 3}, NO{sub y} and moisture were made downwind of Portland, Oregon, as part of a study to characterize the chemistry in a nocturnal urban plume. Air parcels sampled within the urban plume soon after sunset had positive correlations between O{sub 3}, relative humidity, NO{sub y} and aerosol number density. However, the air parcels sampled within the urban plume just before dawn had O{sub 3} mixing ratios that were highly anti-correlated with aerosol number density, NO{sub y} and relative humidity. Back-trajectories from a mesoscale model show that both the post-sunset and pre-dawn parcels came from a common maritime source to the northwest of Portland. The pre-dawn parcels with strong anti-correlations passed directly over Portland in contrast to the other parcels that were found to pass west of Portland. Several gas-phase mechanisms and a heterogeneous mechanism involving the loss of O{sub 3} to the aerosol surface, are examined to explain the observed depletion in O{sub 3} within the pre-dawn parcels that had passed over Portland. (Author)

  11. Enhancing non-refractory aerosol apportionment from an urban industrial site through receptor modeling of complete high time-resolution aerosol mass spectra

    Science.gov (United States)

    McGuire, M. L.; Chang, R. Y.-W.; Slowik, J. G.; Jeong, C.-H.; Healy, R. M.; Lu, G.; Mihele, C.; Abbatt, J. P. D.; Brook, J. R.; Evans, G. J.

    2014-08-01

    Receptor modeling was performed on quadrupole unit mass resolution aerosol mass spectrometer (Q-AMS) sub-micron particulate matter (PM) chemical speciation measurements from Windsor, Ontario, an industrial city situated across the Detroit River from Detroit, Michigan. Aerosol and trace gas measurements were collected on board Environment Canada's Canadian Regional and Urban Investigation System for Environmental Research (CRUISER) mobile laboratory. Positive matrix factorization (PMF) was performed on the AMS full particle-phase mass spectrum (PMFFull MS) encompassing both organic and inorganic components. This approach compared to the more common method of analyzing only the organic mass spectra (PMFOrg MS). PMF of the full mass spectrum revealed that variability in the non-refractory sub-micron aerosol concentration and composition was best explained by six factors: an amine-containing factor (Amine); an ammonium sulfate- and oxygenated organic aerosol-containing factor (Sulfate-OA); an ammonium nitrate- and oxygenated organic aerosol-containing factor (Nitrate-OA); an ammonium chloride-containing factor (Chloride); a hydrocarbon-like organic aerosol (HOA) factor; and a moderately oxygenated organic aerosol factor (OOA). PMF of the organic mass spectrum revealed three factors of similar composition to some of those revealed through PMFFull MS: Amine, HOA and OOA. Including both the inorganic and organic mass proved to be a beneficial approach to analyzing the unit mass resolution AMS data for several reasons. First, it provided a method for potentially calculating more accurate sub-micron PM mass concentrations, particularly when unusual factors are present, in this case the Amine factor. As this method does not rely on a priori knowledge of chemical species, it circumvents the need for any adjustments to the traditional AMS species fragmentation patterns to account for atypical species, and can thus lead to more complete factor profiles. It is expected that this

  12. High Resolution Aerosol Data from MODIS Satellite for Urban Air Quality Studies

    Science.gov (United States)

    Chudnovsky, A.; Lyapustin, A.; Wang, Y.; Tang, C.; Schwartz, J.; Koutrakis, P.

    2013-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) provides daily global coverage, but the 10 km resolution of its aerosol optical depth (AOD) product is not suitable for studying spatial variability of aerosols in urban areas. Recently, a new Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm was developed for MODIS which provides AOD at 1 km resolution. Using MAIAC data, the relationship between MAIAC AOD and PM(sub 2.5) as measured by the 27 EPA ground monitoring stations was investigated. These results were also compared to conventional MODIS 10 km AOD retrievals (MOD04) for the same days and locations. The coefficients of determination for MOD04 and for MAIAC are R(exp 2) =0.45 and 0.50 respectively, suggested that AOD is a reasonably good proxy for PM(sub 2.5) ground concentrations. Finally, we studied the relationship between PM(sub 2.5) and AOD at the intra-urban scale (10 km) in Boston. The fine resolution results indicated spatial variability in particle concentration at a sub-10 kilometer scale. A local analysis for the Boston area showed that the AOD-PM(sub 2.5) relationship does not depend on relative humidity and air temperatures below approximately 7 C. The correlation improves for temperatures above 7 - 16 C. We found no dependence on the boundary layer height except when the former was in the range 250-500 m. Finally, we apply a mixed effects model approach to MAIAC aerosol optical depth (AOD) retrievals from MODIS to predict PM(sub 2.5) concentrations within the greater Boston area. With this approach we can control for the inherent day-to-day variability in the AOD-PM(sub 2.5) relationship, which depends on time-varying parameters such as particle optical properties, vertical and diurnal concentration profiles and ground surface reflectance. Our results show that the model-predicted PM(sub 2.5) mass concentrations are highly correlated with the actual observations (out-of-sample R(exp 2) of 0.86). Therefore, adjustment

  13. Size distributions of n-alkanes, fatty acids and fatty alcohols in springtime aerosols from New Delhi, India.

    Science.gov (United States)

    Kang, Mingjie; Fu, Pingqing; Aggarwal, Shankar G; Kumar, Sudhanshu; Zhao, Ye; Sun, Yele; Wang, Zifa

    2016-12-01

    Size-segregated aerosol samples were collected in New Delhi, India from March 6 to April 6, 2012. Homologous series of n-alkanes (C 19 C 33 ), n-fatty acids (C 12 C 30 ) and n-alcohols (C 16 C 32 ) were measured using gas chromatography/mass spectrometry. Results showed a high-variation in the concentrations and size distributions of these chemicals during non-haze, haze, and dust storm days. In general, n-alkanes, n-fatty acids and n-alcohols presented a bimodal distribution, peaking at 0.7-1.1 μm and 4.7-5.8 μm for fine modes and coarse modes, respectively. Overall, the particulate matter mainly existed in the coarse mode (≥2.1 μm), accounting for 64.8-68.5% of total aerosol mass. During the haze period, large-scale biomass burning emitted substantial fine hydrophilic smoke particles into the atmosphere, which leads to relatively larger GMDs (geometric mean diameter) of n-alkanes in the fine mode than those during the dust storms and non-haze periods. Additionally, the springtime dust storms transported a large quantity of coarse particles from surrounding or local areas into the atmosphere, enhancing organic aerosol concentration and inducing a remarkable size shift towards the coarse mode, which are consistent with the larger GMDs of most organic compounds especially in total and coarse modes. Our results suggest that fossil fuel combustion (e.g., vehicular and industrial exhaust), biomass burning, residential cooking, and microbial activities could be the major sources of lipid compounds in the urban atmosphere in New Delhi. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Molecular characterization of urban organic aerosol in tropical India: contributions of primary emissions and secondary photooxidation

    Directory of Open Access Journals (Sweden)

    P. Q. Fu

    2010-03-01

    small. This study demonstrates that, in addition to fossil fuel combustion and biomass burning, the open-burning of plastics in urban area also contributes to the organic aerosols in South Asia.

  15. On numerical simulation of the global distribution of sulfate aerosol produced by a large volcanic eruption

    Energy Technology Data Exchange (ETDEWEB)

    Pudykiewicz, J.A.; Dastoor, A.P. [Atmospheric Environment Service, Quebec (Canada)

    1994-12-31

    Volcanic eruptions play an important role in the global sulfur cycle of the Earth`s atmosphere and can significantly perturb the global atmospheric chemistry. The large amount of sulfate aerosol produced by the oxidation of SO{sub 2} injected into the atmosphere during volcanic eruptions also has a relatively big influence on the radiative equilibrium of the Earth`s climatic system. The submicron particles of the sulfate aerosol reflect solar radiation more effectively than they trap radiation in the infrared range. The effect of this is observed as cooling of the Earth`s surface. The modification of the global radiation budget following volcanic eruption can subsequently cause significant fluctuations of atmospheric variables on a subclimatic scale. The resulting perturbation of weather patterns has been observed and well documented since the eruptions of Mt. Krakatau and Mt. Tambora. The impact of the sulfate aerosol from volcanic eruptions on the radiative equilibrium of the Earth`s atmosphere was also confirmed by the studies done with Global Circulation Models designed to simulate climate. The objective of the present paper is to present a simple and effective method to estimate the global distribution of the sulfate aerosol produced as a consequence of volcanic eruptions. In this study we will present results of the simulation of global distribution of sulfate aerosol from the eruption of Mt Pinatubo.

  16. Study of emission episodes of urban aerosol by ion beam analytical techniques

    International Nuclear Information System (INIS)

    Angyal, A.; Kertesz, Zs.; Szikszai, Z.; Szoboszlai, Z.; Furu, E.; Csedreki, L.; Daroczi, L.

    2010-01-01

    Complete text of publication follows. Aerosol pollution has impact on the climate and on human health. Thus investigation of atmospheric aerosol is important in urban environment such as Debrecen. One of the main goals of our study was to define the sources of the particles. The hourly evolution of atmospheric aerosol concentration was used to identify sources of fine (aerodynamic diameter < 2,5 μm) and coarse (10 μm ≥ aerodynamic diameter ≥ 2.5 μm) urban particulate matter in Debrecen. In both size fractions sources were found which were characterized by high heavy metal content. In this study we provide accurate information of the sources of coarse mode heavy metals by using nuclear and scanning electron microscopy. Single particle analysis of chosen samples was carried out on the ATOMKI Scanning Nuclear Microprobe Facility. Elemental composition for Z ≥ 6, morphology and size of around 500 coarse mode particles were determined by Scanning Transmission Ion Microscopy, light-element PIXE and PIXE analytical methods. Furthermore Scanning Electron Microscopy (SEM) was used to investigate particles morphology. The main components of the particles were Na, K, Ca, S, P and Fe with traces of Ti, V, Cr, Mn, Ni, Cu, Zn, Co, Pb. S-rich particles were enriched in one or more of the following elements: Na, Ca, K, Fe, Zn. Trace metals (Mn, Cu, Zn, Cr) occurred together Fe supposedly originated from industrial emission or traffic. P appeared in the Ca-rich particles. Particles with high concentration of Ni were rich in V, Fe and S. Thus this source was identified as residual combustion. V-rich particles occurred together with Fe, Mn and Cr. Their possible source was industry. Pb was attached to Ca, Fe, S containing particles. As result of the SEM study the following particle types (Figure 1.) were identified: semitransparent material (S-K-rich, S-Zn-rich, PCa-rich), spherical (FeO, Fe-Ni-Cr-V-rich), cubic (KCl, CaCl) and crystalline (S-Ca-rich). The main sources of

  17. Real-Time Measurement of Electronic Cigarette Aerosol Size Distribution and Metals Content Analysis.

    Science.gov (United States)

    Mikheev, Vladimir B; Brinkman, Marielle C; Granville, Courtney A; Gordon, Sydney M; Clark, Pamela I

    2016-09-01

    Electronic cigarette (e-cigarette) use is increasing worldwide and is highest among both daily and nondaily smokers. E-cigarettes are perceived as a healthier alternative to combustible tobacco products, but their health risk factors have not yet been established, and one of them is lack of data on aerosol size generated by e-cigarettes. We applied a real-time, high-resolution aerosol differential mobility spectrometer to monitor the evolution of aerosol size and concentration during puff development. Particles generated by e-cigarettes were immediately delivered for analysis with minimal dilution and therefore with minimal sample distortion, which is critically important given the highly dynamic aerosol/vapor mixture inherent to e-cigarette emissions. E-cigarette aerosols normally exhibit a bimodal particle size distribution: nanoparticles (11-25nm count median diameter) and submicron particles (96-175nm count median diameter). Each mode has comparable number concentrations (10(7)-10(8) particles/cm(3)). "Dry puff" tests conducted with no e-cigarette liquid (e-liquid) present in the e-cigarette tank demonstrated that under these conditions only nanoparticles were generated. Analysis of the bulk aerosol collected on the filter showed that e-cigarette emissions contained a variety of metals. E-cigarette aerosol size distribution is different from that of combustible tobacco smoke. E-cigarettes generate high concentrations of nanoparticles and their chemical content requires further investigation. Despite the small mass of nanoparticles, their toxicological impact could be significant. Toxic chemicals that are attached to the small nanoparticles may have greater adverse health effects than when attached to larger submicron particles. The e-cigarette aerosol size distribution is different from that of combustible tobacco smoke and typically exhibits a bimodal behavior with comparable number concentrations of nanoparticles and submicron particles. While vaping the e

  18. Implementing electric vehicles in urban distribution: A discrete event simulation

    OpenAIRE

    Lebeau, Philippe; Macharis, Cathy; Mierlo, Joeri Van; Maes, Guillaume

    2013-01-01

    Urban freight transport becomes increasingly important with the development of cities. However, it generates also inefficiencies on social, economic and environmental aspects. A possible solution is the use of urban distribution centres in order to rationalise the deliveries and to operate the last miles with clean vehicles. Electric vehicles are gaining attention lately but some barriers remain. Since costs barriers were already investigated, the paper aimed at evaluating the difference of p...

  19. Particle number size distributions in urban air before and after volatilisation

    Directory of Open Access Journals (Sweden)

    W. Birmili

    2010-05-01

    Full Text Available Aerosol particle number size distributions (size range 0.003–10 μm in the urban atmosphere of Augsburg (Germany were examined with respect to the governing anthropogenic sources and meteorological factors. The two-year average particle number concentration between November 2004 and November 2006 was 12 200 cm−3, i.e. similar to previous observations in other European cities. A seasonal analysis yielded twice the total particle number concentrations in winter as compared to summer as consequence of more frequent inversion situations and enhanced particulate emissions. The diurnal variations of particle number were shaped by a remarkable maximum in the morning during the peak traffic hours. After a mid-day decrease along with the onset of vertical mixing, an evening concentration maximum could frequently be observed, suggesting a re-stratification of the urban atmosphere. Overall, the mixed layer height turned out to be the most influential meteorological parameter on the particle size distribution. Its influence was even greater than that of the geographical origin of the prevailing synoptic-scale air mass.

    Size distributions below 0.8 μm were also measured downstream of a thermodenuder (temperature: 300 °C, allowing to retrieve the volume concentration of non-volatile compounds. The balance of particle number upstream and downstream of the thermodenuder suggests that practically all particles >12 nm contain a non-volatile core while additional nucleation of particles smaller than 6 nm could be observed after the thermodenuder as an interfering artifact of the method. The good correlation between the non-volatile volume concentration and an independent measurement of the aerosol absorption coefficient (R2=0.9 suggests a close correspondence of the refractory and light-absorbing particle fractions. Using the "summation method", an average diameter ratio of particles before and after volatilisation could

  20. Atmospheric Aerosols in Suburb of Prague: The Dynamics of Particle Size Distributions

    Czech Academy of Sciences Publication Activity Database

    Řimnáčová, Daniela; Ždímal, Vladimír; Schwarz, Jaroslav; Smolík, Jiří; Řimnáč, Martin

    2011-01-01

    Roč. 101, č. 3 (2011), s. 539-552 ISSN 0169-8095 Grant - others:MF NF(CZ) CZ0049 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z10300504 Keywords : atm ospheric aerosols * atm ospheric nucleation * part size distribution Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.911, year: 2011

  1. Inversion of multiwavelength Raman lidar data for retrieval of bimodal aerosol size distribution

    Science.gov (United States)

    Veselovskii, Igor; Kolgotin, Alexei; Griaznov, Vadim; Müller, Detlef; Franke, Kathleen; Whiteman, David N.

    2004-02-01

    We report on the feasibility of deriving microphysical parameters of bimodal particle size distributions from Mie-Raman lidar based on a triple Nd:YAG laser. Such an instrument provides backscatter coefficients at 355, 532, and 1064 nm and extinction coefficients at 355 and 532 nm. The inversion method employed is Tikhonov's inversion with regularization. Special attention has been paid to extend the particle size range for which this inversion scheme works to ~10 μm, which makes this algorithm applicable to large particles, e.g., investigations concerning the hygroscopic growth of aerosols. Simulations showed that surface area, volume concentration, and effective radius are derived to an accuracy of ~50% for a variety of bimodal particle size distributions. For particle size distributions with an effective radius of rims along which anthropogenic pollution mixes with marine aerosols. Measurement cases obtained from the Institute for Tropospheric Research six-wavelength aerosol lidar observations during the Indian Ocean Experiment were used to test the capabilities of the algorithm for experimental data sets. A benchmark test was attempted for the case representing anthropogenic aerosols between a broken cloud deck. A strong contribution of particle volume in the coarse mode of the particle size distribution was found.

  2. Aerosol pollution in urban and industrialized area under marine influence: physical-chemistry of particles

    International Nuclear Information System (INIS)

    Rimetz, J.

    2007-12-01

    Harbors for trade are known as highly urbanized and industrialized areas with important maritime, railway and road traffic. Industries are mainly represented by steel, cement works, and oil refineries. The maritime sector is becoming an even larger source of air pollution. Atmospheric NO x , SO 2 , O 3 levels and chemical analysis of airborne particulate matter were monitored in Dunkerque conurbation in 2005 and 2006. This study was included in the IRENI program. In low-pressure conditions, local pollutants are spread out far away the agglomeration, whereas, in high-pressure regimes, the atmospheric stability and sea-breezes allow an accumulation of pollutants over the urban zone. Size-resolved chemical analyses of particulate matter collected as function of the aerodynamic diameter (D a ) were performed. Ions (Na + , NH 4 + , Cl - , NO 3 - , SO 4 2- ), metals (Fe, Zn, Pb, Cd,...) and organic fraction (EC, OC) are associated with sub- or/and super-micron particles. The size, morphology and chemical species of individual particles collected selectively in the 12O 3 , Fe 3 O 4 , PbO,... containing particles emitted in the Dunkerque harbour area and aged sea-salt aerosol particles (NaCl, NaNO 3 ,...) from long range transport of air masses. Thin organic coatings from natural and anthropogenic origin are observed on the particles by ToF-SIMS imaging. (author)

  3. Urban distribution of Phlebotominae in a cutaneous leishmaniasis focus, Argentina

    Directory of Open Access Journals (Sweden)

    Oscar D Salomón

    2008-05-01

    Full Text Available Urbanization and vector domestication are currently proposed as factors that contributed to the recent increase of American cutaneous leishmaniasis (ACL. Is likely also urban transmission? Oran is the main city in the Argentinean hyper-endemic area of ACL, and human cases in urban residences are usually reported. In order to assess the spatial distribution of risk, phlebotomine traps were located in different environments of Oran. A total of 7,787 sand flies were captured: Lutzomyia neivai (98.1%, Lutzomyia migonei (1.2%, Lutzomyia cortelezzii (0.7%, and one Lutzomyia shannoni. During the season of transmission (April-May a single sand fly was obtained in one out of five urban sites, while a trap in a peri-urban pigsty captured up to 2,985 Lu. neivai/night. Captures performed in the other season of vector activity (September-October revealed that small-scale changes in the pigsty environment resulted in noticeable changes in the abundance of Lu. neivai. In addition, in a new neighbourhood, on the fringe of the city, 1,073 Lu. neivai/site were captured in the forested edge but one in the yard of the houses. Therefore, in this urban ACL focus the human-vector effective contact risk is still associated with peri-urban vegetation and ecotone modifications despite the urban residence of the cases.

  4. An effective inversion algorithm for retrieving bimodal aerosol particle size distribution from spectral extinction data

    International Nuclear Information System (INIS)

    He, Zhenzong; Qi, Hong; Yao, Yuchen; Ruan, Liming

    2014-01-01

    The Ant Colony Optimization algorithm based on the probability density function (PDF-ACO) is applied to estimate the bimodal aerosol particle size distribution (PSD). The direct problem is solved by the modified Anomalous Diffraction Approximation (ADA, as an approximation for optically large and soft spheres, i.e., χ⪢1 and |m−1|⪡1) and the Beer–Lambert law. First, a popular bimodal aerosol PSD and three other bimodal PSDs are retrieved in the dependent model by the multi-wavelength extinction technique. All the results reveal that the PDF-ACO algorithm can be used as an effective technique to investigate the bimodal PSD. Then, the Johnson's S B (J-S B ) function and the modified beta (M-β) function are employed as the general distribution function to retrieve the bimodal PSDs under the independent model. Finally, the J-S B and M-β functions are applied to recover actual measurement aerosol PSDs over Beijing and Shanghai obtained from the aerosol robotic network (AERONET). The numerical simulation and experimental results demonstrate that these two general functions, especially the J-S B function, can be used as a versatile distribution function to retrieve the bimodal aerosol PSD when no priori information about the PSD is available. - Highlights: • Bimodal PSDs are retrieved by ACO based on probability density function accurately. • J-S B and M-β functions can be used as the versatile function to recover bimodal PSDs. • Bimodal aerosol PSDs can be estimated by J-S B function more reasonably

  5. Urban particle size distributions during two contrasting dust events originating from Taklimakan and Gobi Deserts

    International Nuclear Information System (INIS)

    Zhao, Suping; Yu, Ye; Xia, Dunsheng; Yin, Daiying; He, Jianjun; Liu, Na; Li, Fang

    2015-01-01

    The dust origins of the two events were identified using HYSPLIT trajectory model and MODIS and CALIPSO satellite data to understand the particle size distribution during two contrasting dust events originated from Taklimakan and Gobi deserts. The supermicron particles significantly increased during the dust events. The dust event from Gobi desert affected significantly on the particles larger than 2.5 μm, while that from Taklimakan desert impacted obviously on the particles in 1.0–2.5 μm. It is found that the particle size distributions and their modal parameters such as VMD (volume median diameter) have significant difference for varying dust origins. The dust from Taklimakan desert was finer than that from Gobi desert also probably due to other influencing factors such as mixing between dust and urban emissions. Our findings illustrated the capacity of combining in situ, satellite data and trajectory model to characterize large-scale dust plumes with a variety of aerosol parameters. - Highlights: • Dust particle size distributions had large differences for varying origins. • Dust originating from Taklimakan Desert was finer than that from Gobi Desert. • Effect of dust on the supermicron particles was obvious. • PM_1_0 concentrations increased by a factor of 3.4–25.6 during the dust event. - Dust particle size distributions had large differences for varying origins, which may be also related to other factors such as mixing between dust and urban emissions.

  6. Variations in time and space of trace metal aerosol concentrations in urban areas and their surroundings

    Science.gov (United States)

    Moreno, T.; Querol, X.; Alastuey, A.; Reche, C.; Cusack, M.; Amato, F.; Pandolfi, M.; Pey, J.; Richard, A.; Prévôt, A. S. H.; Furger, M.; Gibbons, W.

    2011-09-01

    Using an unprecedentedly large geochemical database, we compare temporal and spatial variations in inhalable trace metal background concentrations in a major city (Barcelona, Spain) and at a nearby mountainous site (Montseny) affected by the urban plume. Both sites are contaminated by technogenic metals, with V, Pb, Cu, Zn, Mn, Sn, Bi, Sb and Cd all showing upper continental crust (UCC) normalised values >1 in broadly increasing order. The highest metal concentrations usually occur during winter at Barcelona and summer in Montseny. This seasonal difference was especially marked at the remote mountain site in several elements such as Ti and Rare Earth Elements, which recorded campaign maxima, exceeding PM10 concentrations seen in Barcelona. The most common metals were Zn, Ti, Cu, Mn, Pb and V. Both V and Ni show highest concentrations in summer, and preferentially fractionate into the finest PM sizes (PM1/PM10 > 0.5) especially in Barcelona, this being attributed to regionally dispersed contamination from fuel oil combustion point sources. Within the city, hourly metal concentrations are controlled either by traffic (rush hour double peak for Cu, Sb, Sn, Ba) or industrial plumes (morning peak of Ni, Mn, Cr generated outside the city overnight), whereas at Montseny metal concentrations rise during the morning to a single, prolonged afternoon peak as contaminated air transported by the sea breeze moves into the mountains. Our exceptional database, which includes hourly measurements of chemical concentrations, demonstrates in more detail than previous studies the spatial and temporal variability of urban pollution by trace metals in a given city. Technogenic metalliferous aerosols are commonly fine in size and therefore potentially bioavailable, emphasising the case for basing urban background PM characterisation not only on physical parameters such as mass but also on sample chemistry and with special emphasis on trace metal content.

  7. LASE Measurements of Water Vapor, Aerosol, and Cloud Distributions in Saharan Air Layers and Tropical Disturbances

    Science.gov (United States)

    Ismail, Syed; Ferrare, Richard A.; Browell, Edward V.; Kooi, Susan A.; Dunion, Jason P.; Heymsfield, Gerry; Notari, Anthony; Butler, Carolyn F.; Burton, Sharon; Fenn, Marta; hide

    2010-01-01

    LASE (Lidar Atmospheric Sensing Experiment) on-board the NASA DC-8 measured high resolution profiles of water vapor and aerosols, and cloud distributions in 14 flights over the eastern North Atlantic during the NAMMA (NASA African Monsoon Multidisciplinary Analyses) field experiment. These measurements were used to study African easterly waves (AEWs), tropical cyclones (TCs), and the Saharan Air Layer(s) (SAL). Interactions between the SAL and tropical air were observed during the early stages of the TC development. These LASE measurements represent the first simultaneous water vapor and aerosol lidar measurements to study the SAL and its impact on AEWs and TCs. Examples of profile measurements of aerosol scattering ratios, aerosol extinction coefficients, aerosol optical thickness, water vapor mixing ratios, RH, and temperature are presented to illustrate their characteristics in SAL, convection, and clear air regions. LASE data suggest that the SAL suppresses low-altitude convection at the convection-SAL interface region. Mid-level convection associated with the AEW and transport are likely responsible for high water vapor content observed in the southern regions of the SAL on August 20, 2008. This interaction is responsible for the transfer of about 7 x 10(exp 15) J latent heat energy within a day to the SAL. Measurements of lidar extinction-to-backscatter ratios in the range 36+/-5 to 45+/-5 are within the range of measurements from other lidar measurements of dust. LASE aerosol extinction and water vapor profiles are validated by comparison with onboard in situ aerosol measurements and GPS dropsonde water vapor soundings, respectively.

  8. Aerosol optical properties and radiative effects: Assessment of urban aerosols in central China using 10-year observations

    Science.gov (United States)

    Zhang, Ming; Ma, Yingying; Gong, Wei; Liu, Boming; Shi, Yifan; Chen, ZhongYong

    2018-06-01

    Poor air quality episodes are common in central China. Here, based on 10 years of ground-based sun-photometric observations, aerosol optical and radiative forcing characteristics were analyzed in Wuhan, the biggest metropolis in central China. Aerosol optical depth (AOD) in the last decade declined significantly, while the Ångström exponent (AE) showed slight growth. Single scattering albedo (SSA) at 440 nm reached the lowest value (0.87) in winter and highest value (0.93) in summer. Aerosol parameters derived from sun-photometric observations were used as input in a radiative transfer model to calculate aerosol radiative forcing (ARF) on the surface in ultraviolet (UV), visible (VIS), near-infrared (NIR), and shortwave (SW) spectra. ARFSW sustained decreases (the absolute values) over the last 10 years. In terms of seasonal variability, due to the increases in multiple scattering effects and attenuation of the transmitted radiation as AOD increased, ARF in summer displayed the largest value (-73.94 W/m2). After eliminating the influence of aerosol loading, the maximum aerosol radiative forcing efficiency in SW range (ARFESW) achieved a value of -64.5 W/m2/AOD in April. The ARFE change in each sub-interval spectrum was related to the change in SSA and effective radius of fine mode particles (Refff), that is, ARFE increased with the decreases in SSA and Refff. The smallest contribution of ARFENIR to ARFESW was 34.11% under strong absorbing and fine particle conditions, and opposite results were found for the VIS range, whose values were always over 51.82%. Finally, due to the serious air pollution and frequency of haze day, aerosol characteristics in haze and clear days were analyzed. The percentage of ARFENIR increased from 35.71% on clear-air days to 37.63% during haze periods, while both the percentage of ARFEUV and ARFENIR in ARFESW kept decreasing. The results of this paper should help us to better understand the effect of aerosols on solar spectral radiation

  9. Hourly elemental concentrations in PM2.5 aerosols sampled simultaneously at urban background and road site during SAPUSS -diurnal variations and PMF receptor modelling

    NARCIS (Netherlands)

    Dall'Osto, M.; Querol, X.; Amato, F.; Karanasiou, A.; Lucarelli, F.; Nava, S.; Calzolai, G.; Chiari, M.

    2013-01-01

    Hourly-resolved aerosol chemical speciation data can be a highly powerful tool to determine the source origin of atmospheric pollutants in urban environments. Aerosol mass concentrations of seventeen elements (Na, Mg, Al, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Pb) were obtained by time

  10. Size distribution dynamics reveal particle-phase chemistry in organic aerosol formation

    Science.gov (United States)

    Shiraiwa, Manabu; Yee, Lindsay D.; Schilling, Katherine A.; Loza, Christine L.; Craven, Jill S.; Zuend, Andreas; Ziemann, Paul J.; Seinfeld, John H.

    2013-01-01

    Organic aerosols are ubiquitous in the atmosphere and play a central role in climate, air quality, and public health. The aerosol size distribution is key in determining its optical properties and cloud condensation nucleus activity. The dominant portion of organic aerosol is formed through gas-phase oxidation of volatile organic compounds, so-called secondary organic aerosols (SOAs). Typical experimental measurements of SOA formation include total SOA mass and atomic oxygen-to-carbon ratio. These measurements, alone, are generally insufficient to reveal the extent to which condensed-phase reactions occur in conjunction with the multigeneration gas-phase photooxidation. Combining laboratory chamber experiments and kinetic gas-particle modeling for the dodecane SOA system, here we show that the presence of particle-phase chemistry is reflected in the evolution of the SOA size distribution as well as its mass concentration. Particle-phase reactions are predicted to occur mainly at the particle surface, and the reaction products contribute more than half of the SOA mass. Chamber photooxidation with a midexperiment aldehyde injection confirms that heterogeneous reaction of aldehydes with organic hydroperoxides forming peroxyhemiacetals can lead to a large increase in SOA mass. Although experiments need to be conducted with other SOA precursor hydrocarbons, current results demonstrate coupling between particle-phase chemistry and size distribution dynamics in the formation of SOAs, thereby opening up an avenue for analysis of the SOA formation process. PMID:23818634

  11. Size distribution dynamics reveal particle-phase chemistry in organic aerosol formation.

    Science.gov (United States)

    Shiraiwa, Manabu; Yee, Lindsay D; Schilling, Katherine A; Loza, Christine L; Craven, Jill S; Zuend, Andreas; Ziemann, Paul J; Seinfeld, John H

    2013-07-16

    Organic aerosols are ubiquitous in the atmosphere and play a central role in climate, air quality, and public health. The aerosol size distribution is key in determining its optical properties and cloud condensation nucleus activity. The dominant portion of organic aerosol is formed through gas-phase oxidation of volatile organic compounds, so-called secondary organic aerosols (SOAs). Typical experimental measurements of SOA formation include total SOA mass and atomic oxygen-to-carbon ratio. These measurements, alone, are generally insufficient to reveal the extent to which condensed-phase reactions occur in conjunction with the multigeneration gas-phase photooxidation. Combining laboratory chamber experiments and kinetic gas-particle modeling for the dodecane SOA system, here we show that the presence of particle-phase chemistry is reflected in the evolution of the SOA size distribution as well as its mass concentration. Particle-phase reactions are predicted to occur mainly at the particle surface, and the reaction products contribute more than half of the SOA mass. Chamber photooxidation with a midexperiment aldehyde injection confirms that heterogeneous reaction of aldehydes with organic hydroperoxides forming peroxyhemiacetals can lead to a large increase in SOA mass. Although experiments need to be conducted with other SOA precursor hydrocarbons, current results demonstrate coupling between particle-phase chemistry and size distribution dynamics in the formation of SOAs, thereby opening up an avenue for analysis of the SOA formation process.

  12. Growth Kinetics and Size Distribution Dynamics of Viscous Secondary Organic Aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Zaveri, Rahul A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Atmospheric Science and Global Change Div. (ASGC); Shilling, John E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Atmospheric Science and Global Change Div. (ASGC); Zelenyuk, Alla [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical Sciences Div.; Liu, Jiumeng [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Atmospheric Science and Global Change Div. (ASGC); Bell, David M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical Sciences Div.; Paul Scherrer Inst. (PSI), Villigen (Switzerland). Lab. of Atmospheric Chemistry; D’Ambro, Emma L. [Univ. of Washington, Seattle, WA (United States). Dept. of Atmospheric Sciences and Dept. of Chemistry; Gaston, Cassandra J. [Univ. of Washington, Seattle, WA (United States). Dept. of Atmospheric Sciences; Univ. of Miami, Miami, FL (United States). Rosenstiel School of Marine and Atmospheric Science; Thornton, Joel A. [Univ. of Washington, Seattle, WA (United States). Dept. of Atmospheric Sciences and Dept. of Chemistry; Laskin, Alexander [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Purdue Univ., West Lafayette, IN (United States). Dept. of Chemistry; Lin, Peng [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Purdue Univ., West Lafayette, IN (United States). Dept. of Chemistry; Wilson, Jacqueline [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical Sciences Div.; Easter, Richard C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Atmospheric Science and Global Change Div. (ASGC); Wang, Jian [Brookhaven National Lab. (BNL), Upton, NY (United States). Environmental & Climate Sciences Dept.; Bertram, Allan K. [Univ. of British Columbia, Vancouver, BC (Canada). Dept. of Chemistry; Martin, Scot T. [Harvard Univ., Cambridge, MA (United States). School of Engineering and Applied Sciences (SEAS) and Dept. of Earth and Planetary Sciences; Seinfeld, John H. [California Inst. of Technology (CalTech), Pasadena, CA (United States). Div. of Chemistry and Chemical Engineering and Div. of Engineering and Applied Science; Worsnop, Douglas R. [Aerodyne Research, Billerica, MA (United States). Center for Aerosol and Cloud Chemistry

    2017-12-15

    Low bulk diffusivity inside viscous semisolid atmospheric secondary organic aerosol (SOA) can prolong equilibration time scale, but its broader impacts on aerosol growth and size distribution dynamics are poorly understood. In this article, we present quantitative insights into the effects of bulk diffusivity on the growth and evaporation kinetics of SOA formed under dry conditions from photooxidation of isoprene in the presence of a bimodal aerosol consisting of Aitken (ammonium sulfate) and accumulation (isoprene or α-pinene SOA) mode particles. Aerosol composition measurements and evaporation kinetics indicate that isoprene SOA is composed of several semivolatile organic compounds (SVOCs), with some reversibly reacting to form oligomers. Model analysis shows that liquid-like bulk diffusivities can be used to fit the observed evaporation kinetics of accumulation mode particles but fail to explain the growth kinetics of bimodal aerosol by significantly under-predicting the evolution of the Aitken mode. In contrast, the semisolid scenario successfully reproduces both evaporation and growth kinetics, with the interpretation that hindered partitioning of SVOCs into large viscous particles effectively promotes the growth of smaller particles that have shorter diffusion time scales. This effect has important implications for the growth of atmospheric ultrafine particles to climatically active sizes.

  13. Vertical Distribution of Dust and Water Ice Aerosols from CRISM Limb-geometry Observations

    Science.gov (United States)

    Smith, Michael Doyle; Wolff, Michael J.; Clancy, Todd; Kleinbohl, Armin; Murchie, Scott L.

    2013-01-01

    [1] Near-infrared spectra taken in a limb-viewing geometry by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on board the Mars Reconnaissance Orbiter provide a useful tool for probing atmospheric structure. Specifically, the observed radiance as a function of wavelength and height above the limb enables the vertical distribution of both dust and water ice aerosols to be retrieved. More than a dozen sets of CRISM limb observations have been taken so far providing pole-to-pole cross sections, spanning more than a full Martian year. Radiative transfer modeling is used to model the observations taking into account multiple scattering from aerosols and the spherical geometry of the limb observations. Both dust and water ice vertical profiles often show a significant vertical structure for nearly all seasons and latitudes that is not consistent with the well-mixed or Conrath-v assumptions that have often been used in the past for describing aerosol vertical profiles for retrieval and modeling purposes. Significant variations are seen in the retrieved vertical profiles of dust and water ice aerosol as a function of season. Dust typically extends to higher altitudes (approx. 40-50km) during the perihelion season than during the aphelion season (water ice clouds are common, and water ice aerosols are observed to cap the dust layer in all seasons.

  14. Evolution of multispectral aerosol optical properties in a biogenically-influenced urban environment during the CARES campaign

    Science.gov (United States)

    Gyawali, M.; Arnott, W. P.; Zaveri, R. A.; Song, C.; Pekour, M.; Flowers, B.; Dubey, M. K.; Setyan, A.; Zhang, Q.; Harworth, J. W.; Radney, J. G.; Atkinson, D. B.; China, S.; Mazzoleni, C.; Gorkowski, K.; Subramanian, R.; Jobson, B. T.; Moosmüller, H.

    2013-03-01

    Ground-based aerosol measurements made in June 2010 within Sacramento urban area (site T0) and at a 40-km downwind location (site T1) in the forested Sierra Nevada foothills area are used to investigate the evolution of multispectral optical properties as the urban aerosols aged and interacted with biogenic emissions. Along with black carbon and non-refractory aerosol mass and composition observations, spectral absorptio (βabs), scattering (βsca), and extinction (βext) coefficients for wavelengths ranging from 355 to 1064 nm were measured at both sites using photoacoustic (PA) instruments with integrating nephelometers and using cavity ring-down (CRD) instruments. The daytime average Ångström exponent of absorption (AEA) was ~1.6 for the wavelength pair 405 and 870 nm at T0, while it was ~1.8 for the wavelength pair 355 and 870 nm at T1, indicating a modest wavelength-dependent enhancement of absorption at both sites throughout the study. The measured and Mie theory calculations of multispectral βsca showed good correlation (R2=0.85-0.94). The average contribution of supermicron aerosol (mainly composed of sea salt particles advected in from the Pacific Ocean) to the total scattering coefficient ranged from less than 20% at 405 nm to greater than 80% at 1064 nm. From 22 to 28 June, secondary organic aerosol mass increased significantly at both sites due to increased biogenic emissions coupled with intense photochemical activity and air mass recirculation in the area. During this period, the short wavelength scattering coefficients at both sites gradually increased due to increase in the size of submicron aerosols. At the same time, BC mass-normalized absorption cross-section (MAC) values for ultraviolet wavelengths at T1 increased by ~60% compared to the relatively less aged urban emissions at the T0 site. In contrast, the average MAC values for 870 nm wavelength were identical at both sites. These results suggest formation of moderately brown secondary

  15. Chemical composition, sources and evolution processes of aerosol at an urban site in Yangtze River Delta, China during wintertime

    Science.gov (United States)

    Zhang, Yunjiang; Tang, Lili; Yu, Hongxia; Wang, Zhuang; Sun, Yele; Qin, Wei; Chen, Wentai; Chen, Changhong; Ding, Aijun; Wu, Jing; Ge, Shun; Chen, Cheng; Zhou, Hong-cang

    2015-12-01

    To investigate the composition, sources and evolution processes of submicron aerosol during wintertime, a field experiment was conducted during December 1-31, 2013 in urban Nanjing, a megacity in Yangtze River Delta of China. Non-refractory submicron aerosol (NR-PM1) species were measured with an Aerodyne Aerosol Chemical Speciation Monitor. NR-PM1 is dominated by secondary inorganic aerosol (55%) and organic aerosol (OA, 42%) during haze periods. Six OA components were identified by positive matrix factorization of the OA mass spectra. The hydrocarbon-like OA and cooking-related OA represent the local traffic and cooking sources, respectively. A highly oxidized factor related to biomass burning OA accounted for 15% of the total OA mass during haze periods. Three types of oxygenated OA (OOA), i.e., a less-oxidized OOA (LO-OOA), a more-oxidized OOA (MO-OOA), and a low-volatility OOA (LV-OOA), were identified. LO-OOA is likely associated with fresh urban secondary OA. MO-OOA likely represents photochemical products showing a similar diurnal cycle to nitrate with a pronounced noon peak. LV-OOA appears to be a more oxidized factor with a pronounced noon peak. The OA composition is dominated by secondary species, especially during haze events. LO-OOA, MO-OOA and LV-OOA on average account for 11%, (18%), 24% (21%) and 23% (18%) of the total OA mass for the haze (clean) periods respectively. Analysis of meteorological influence suggested that regional transport from the northern and southeastern areas of the city is responsible for large secondary and low-volatility aerosol formation.

  16. Investigation of size-fractionated urban aerosol and trace gases in Budapest by nuclear-related and other analytical techniques

    International Nuclear Information System (INIS)

    Salma, I.; Maenhaut, W.; Zemplen-Papp, E.; Bobvos, J.

    1998-01-01

    An air pollution study was conducted at two urban residential sites in Budapest (one representing the downtown, the other representing a wooded suburb) from 9 April till 17 May 1996. Size-fractionated aerosol samples were simultaneously collected on a daily basis, and meteorological conditions were recorded at both sampling sites. Stacked filter units (SFUs) with an upper size inlet cut-off were used as sampling device separating the urban aerosol into a coarse (about 10-2 μm equivalent aerodynamic diameter, EAD) and a fine ( 2 , SO 2 , CO and the total mass of the suspended particulate matter were measured every half hour at one of the sampling sites by commercial equipment. The SFU filters were analyzed by gravimetry for the total particle mass, by a light reflectance technique for black carbon, by particle-induced X-ray emission analysis and instrumental neutron activation analysis for elemental composition (in combination for up to 40-45 elements). The analytical results were used for characterizing the levels and the multi-elemental composition of the urban aerosol at both sampling sites and for both size fractions, for investigating the atmospheric concentrations and diurnal variation of some criteria pollutants, and for comparing the time-trends of aerosols and trace gases. Identification of the major source types of the aerosol fractions and trace gases, and assessment of the relative contribution from these sources are to be accomplished by multivariate receptor modeling. The present paper reports on the status of the air pollution study, and gives a discussion of the results

  17. Characteristics, sources and evolution of fine aerosol (PM1) at urban, coastal and forest background sites in Lithuania

    Science.gov (United States)

    Masalaite, A.; Holzinger, R.; Remeikis, V.; Röckmann, T.; Dusek, U.

    2017-01-01

    The chemical and isotopic composition of organic aerosol (OA) samples collected on PM1 filters was determined as a function of desorption temperature to investigate the main sources of organic carbon and the effects of photochemical processing on atmospheric aerosol. The filter samples were collected at an urban (54°38‧ N, 25°18‧ E), coastal (55°55‧ N, 21°00‧ E) and forest (55°27‧ N, 26°00' E) site in Lithuania in March 2013. They can be interpreted as winter-time samples because the monthly averaged temperature was -4 °C. The detailed chemical composition of organic compounds was analysed with a thermal desorption PTR-MS. The mass concentration of organic aerosol at the forest site was roughly by a factor of 30 lower than at the urban and coastal site. This fact could be an indication that in this cold month the biogenic secondary organic aerosol (SOA) formation was very low. Moreover, the organic aerosol collected at the forest site was more refractory and contained a larger fraction of heavy molecules with m/z > 200. The isotopic composition of the aerosol was used to differentiate the two main sources of organic aerosol in winter, i.e. biomass burning (BB) and fossil fuel (FF) combustion. Organic aerosol from biomass burning is enriched in 13C compared to OA from fossil fuel emissions. δ13COC values of the OA samples showed a positive correlation with the mass fraction of several individual organic compounds. Most of these organic compounds contained nitrogen indicating that organic nitrogen compounds formed during the combustion of biomass may be indicative of BB. Other compounds that showed negative correlations with δ13COC were possibly indicative of FF. These compounds included heavy hydrocarbons and were on the average less oxidized than the bulk organic carbon. The correlation of δ13COC and the O/C ratio was positive at low but negative at high desorption temperatures at the forest site. We propose that this might be due to

  18. A case study of the highly time-resolved evolution of aerosol chemical and optical properties in urban Shanghai, China

    Directory of Open Access Journals (Sweden)

    Y. Huang

    2013-04-01

    Full Text Available Characteristics of the chemical and optical properties of aerosols in urban Shanghai and their relationship were studied over a three-day period in October 2011. A suite of real-time instruments, including an Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS, a Monitor for AeRosols and GAses (MARGA, a Cavity Ring Down Spectrometer (CRDS, a nephelometer and a Scanning Mobility Particle Sizer (SMPS, was employed to follow the quick changes of the aerosol properties within the 72 h sampling period. The origin of the air mass arriving in Shanghai during this period shifted from the East China Sea to the northwest area of China, offering a unique opportunity to observe the evolution of aerosols influenced by regional transport from the most polluted areas in China. According to the meteorological conditions and temporal characterizations of the chemical and optical properties, the sampling period was divided into three periods. During Period 1 (00:00–23:00 LT, 13 October, the aerosols in urban Shanghai were mainly fresh and the single scattering albedo varied negatively with the emission of elemental carbon, indicating that local sources dominated. Period 2 (23:00 LT on 13 October to 10:00 LT on 15 October was impacted by regionally transported pollutants and had the highest particulate matter (PM mass loading and the lowest particle acidity, characterized by large fractions of aged particles and high secondary ion (nitrate, sulfate and ammonium mass concentrations. Comparison between ATOFMS particle acidity and quantitative particle acidity by MARGA indicated the significance of semi-quantitative calculation in ATOFMS. Two sub-periods were identified in Period 2 based on the scattering efficiency of PM1 mass. Period 3 (from 10:00 LT on 15 October to 00:00 LT on 16 October had a low PM1/PM10 ratio and a new particle formation event. The comparison of these sub-periods highlights the influence of particle mixing state on aerosol optical properties

  19. Spectral dependence of aerosol light absorption at an urban and a remote site over the Tibetan Plateau.

    Science.gov (United States)

    Zhu, Chong-Shu; Cao, Jun-Ji; Hu, Ta-Feng; Shen, Zhen-Xing; Tie, Xue-Xi; Huang, Hong; Wang, Qi-Yuan; Huang, Ru-Jin; Zhao, Zhu-Zi; Močnik, Griša; Hansen, Anthony D A

    2017-07-15

    We present a study of aerosol light absorption by using a 7-wavelength Aethalometer model AE33 at an urban site (Lhasa) and a remote site (Lulang) in the Tibetan Plateau. Approximately 5 times greater aerosol absorption values were observed at Lhasa (53±46Mm -1 at 370nm and 20±18Mm -1 at 950nm, respectively) in comparison to Lulang (15±19Mm -1 at 370nm and 4±5Mm -1 at 950nm, respectively). Black carbon (BC) was the dominant light absorbing aerosol component at all wavelengths. The brown carbon (BrC) absorption at 370nm is 32±15% of the total aerosol absorption at Lulang, whereas it is 8±6% at Lhasa. Higher value of absorption Ångström exponent (AAE, 370-950nm) was obtained for Lulang (1.18) than that for Lhasa (1.04) due to the presence of BrC. The AAEs (370-950nm) of BrC were directly extracted at Lulang (3.8) and Lhasa (3.3). The loading compensation parameters (k) increased with wavelengths for both sites, and lower values were obtained at Lulang than those observed at Lhasa for all wavelengths. This study underlines the relatively high percentage of BrC absorption contribution in remote area compared to urban site over the Tibetan Plateau. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Cloud residues and interstitial aerosols from non-precipitating clouds over an industrial and urban area in northern China

    Science.gov (United States)

    Li, Weijun; Li, Peiren; Sun, Guode; Zhou, Shengzhen; Yuan, Qi; Wang, Wenxing

    2011-05-01

    Most studies of aerosol-cloud interactions have been conducted in remote locations; few have investigated the characterization of cloud condensation nuclei (CCN) over highly polluted urban and industrial areas. The present work, based on samples collected at Mt. Tai, a site in northern China affected by nearby urban and industrial air pollutant emissions, illuminates CCN properties in a polluted atmosphere. High-resolution transmission electron microscopy (TEM) was used to obtain the size, composition, and mixing state of individual cloud residues and interstitial aerosols. Most of the cloud residues displayed distinct rims which were found to consist of soluble organic matter (OM). Nearly all (91.7%) cloud residues were attributed to sulfate-related salts (the remainder was mostly coarse crustal dust particles with nitrate coatings). Half the salt particles were internally mixed with two or more refractory particles (e.g., soot, fly ash, crustal dust, CaSO 4, and OM). A comparison between cloud residues and interstitial particles shows that the former contained more salts and were of larger particle size than the latter. In addition, a somewhat high number scavenging ratio of 0.54 was observed during cloud formation. Therefore, the mixtures of salts with OMs account for most of the cloud-nucleating ability of the entire aerosol population in the polluted air of northern China. We advocate that both size and composition - the two influential, controlling factors for aerosol activation - should be built into all regional climate models of China.

  1. Variations in the OM/OC ratio of urban organic aerosol next to a major roadway.

    Science.gov (United States)

    Brown, Steven G; Lee, Taehyoung; Roberts, Paul T; Collett, Jeffrey L

    2013-12-01

    Understanding the organic matter/organic carbon (OM/OC) ratio in ambient particulate matter (PM) is critical to achieve mass closure in routine PM measurements, to assess the sources of and the degree of chemical processing organic aerosol particles have undergone, and to relate ambient pollutant concentrations to health effects. Of particular interest is how the OM/OC ratio varies in the urban environment, where strong spatial and temporal gradients in source emissions are common. We provide results of near-roadway high-time-resolution PM1 OM concentration and OM/OC ratio observations during January 2008 at Fyfe Elementary School in Las Vegas, NV, 18 m from the U.S. 95 freeway soundwall, measured with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-AMS). The average OM/OC ratio was 1.54 (+/- 0.20 standard deviation), typical of environments with a low amount of secondary aerosol formation. The 2-min average OM/OC ratios varied between 1.17 and 2.67, and daily average OM/OC ratios varied between 1.44 and 1.73. The ratios were highest during periods of low OM concentrations and generally low during periods of high OM concentrations. OM/OC ratios were low (1.52 +/- 0.14, on average) during the morning rush hour (average OM = 2.4 microg/m3), when vehicular emissions dominate this near-road measurement site. The ratios were slightly lower (1.46 +/- 0.10) in the evening (average OM = 6.3 microg/m3), when a combination of vehicular and fresh residential biomass burning emissions was typically present during times with temperature inversions. The hourly averaged OM/OC ratio peaked at 1.66 at midday. OM concentrations were similar regardless of whether the monitoring site was downwind or upwind of the adjacent freeway throughout the day, though they were higher during stagnant conditions (wind speed < 0.5 m/sec). The OM/OC ratio generally varied more with time of day than with wind direction and speed.

  2. The size distribution of marine atmospheric aerosol with regard to primary biological aerosol particles over the South Atlantic Ocean

    Science.gov (United States)

    Matthias-Maser, Sabine; Brinkmann, Jutta; Schneider, Wilhelm

    The marine atmosphere is characterized by particles which originate from the ocean and by those which reached the air by advection from the continent. The bubble-burst mechanism produces both sea salt as well as biological particles. The following article describes the determination of the size distribution of marine aerosol particles with special emphasis on the biological particles. Th data were obtained on three cruises with the German Research Vessel "METEOR" crossing the South Atlantic Ocean. The measurements showed that biological particles amount to 17% in number and 10% in volume concentration. Another type of particle became obvious in the marine atmosphere, the biologically contaminated particle, i.e. particles which consist partly (approximately up to one-third) of biological matter. Their concentration in the evaluated size class ( r>2 μm) is higher than the concentration of the pure biological particles. The concentrations vary over about one to two orders of magnitude during all cruises.

  3. Urban aerosol in Oporto, Portugal: Chemical characterization of PM10 and PM2.5

    Science.gov (United States)

    Custódio, Danilo; Ferreira, Catarina; Alves, Célia; Duarte, Mácio; Nunes, Teresa; Cerqueira, Mário; Pio, Casimiro; Frosini, Daniele; Colombi, Cristina; Gianelle, Vorne; Karanasiou, Angeliki; Querol, Xavier

    2014-05-01

    Several urban and industrial areas in Southern Europe are not capable of meeting the implemented EU standards for particulate matter. Efficient air quality management is required in order to ensure that the legal limits are not exceeded and that the consequences of poor air quality are controlled and minimized. Many aspects of the direct and indirect effects of suspended particulate matter on climate and public health are not well understood. The temporal variation of the chemical composition is still demanded, since it enables to adopt off-set strategies and to better estimate the magnitude of anthropogenic forcing on climate. This study aims to provide detailed information on concentrations and chemical composition of aerosol from Oporto city, an urban center in Southern Europe. This city is located near the coast line in the North of Portugal, being the country's second largest urban area. Moreover, Oporto city economic prospects depend heavily on a diversified industrial park, which contribute to air quality degradation. Another strong source of air pollution is traffic. The main objectives of this study are: 1) to characterize the chemical composition of PM10 and PM2.5 by setting up an orchestra of aerosol sampling devices in a strategic place in Oporto; 2) to identify the sources of particles exploring parameters such as organic and inorganic markers (e.g. sugars as tracers for biomass burning; metals and elemental carbon for industrial and vehicular emissions); 3) to evaluate long range transport of pollutants using back trajectory analysis. Here we present data obtained between January 2013 and January 2014 in a heavy traffic roadside sampling site located in the city center. Different PM10 and PM2.5 samplers were operated simultaneously in order to collect enough mass on different filter matrixes and to fulfill the requirements of analytical methodologies. More than 100 aerosol samples were collected and then analysed for their mass concentration and

  4. Spatio-temporal distribution of absorbing and non-absorbing aerosols derived from Aura-OMI Aerosol Index over Greece

    Science.gov (United States)

    Kaskaoutis, D. G.; Nastos, P. T.; Kosmopoulos, P. G.; Kambezidis, H. D.; Kharol, S. K.; Badarinath, K. V. S.

    2009-04-01

    The Aerosol Index (AI) observations derived from the Ozone Monitoring Instrument (OMI) on board the Dutch-Finnish Aura satellite are analyzed over Greece covering the whole period of the OMI available data, from September 2004 to August 2008. The objective of this study was to analyze the spatial, seasonal and inter-annual variability of AI over Greece, detected by OMI during 2004-2008, with an evaluation of potential contributing factors, including precipitation and long-range transport (Sahara dust and European pollution). The AI data cover the whole Greek territory (34o-42oN, 20o-28oE) with a spatial resolution of 0.25o x 0.25o (13 km x 24 km at nadir). The results show significant spatial and temporal variability of the seasonal and monthly mean AI, with higher values at the southern parts and lower values over northern Greece. On the other hand, the AI values do not show significant differences between the western and eastern parts and, therefore, the longitude-averaged AI values can be utilized to reveal the strong south-to-north gradient. This gradient significantly changes from season to season being more intense in spring and summer, while it is minimized in winter. Another significant remark is the dominance of negative AI values over northern Greece in the summer months, indicating the presence of non-UV absorbing aerosols, such as sulfate and sea-salt particles. The great geographical extent of the negative AI values in the summer months is indicative of long-range transport of such aerosols. In contrast, the high positive AI values over south Greece, mainly in spring, clearly reveal the UV-absorbing nature of desert-dust particles affecting the area during Saharan dust events. Synoptically, the spatial distribution in OMI-AI values was related to the Saharan dust events mainly over southern Greece and to the trans-boundary-pollution transport, consisting mainly of sulfate particles, in northern Greece. The annual variation of spatial-averaged AI values

  5. Aerosol formation from high-velocity uranium drops: Comparison of number and mass distributions. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Rader, D.J.; Benson, D.A.

    1995-05-01

    This report presents the results of an experimental study of the aerosol produced by the combustion of high-velocity molten-uranium droplets produced by the simultaneous heating and electromagnetic launch of uranium wires. These tests are intended to simulate the reduction of high-velocity fragments into aerosol in high-explosive detonations or reactor accidents involving nuclear materials. As reported earlier, the resulting aerosol consists mainly of web-like chain agglomerates. A condensation nucleus counter was used to investigate the decay of the total particle concentration due to coagulation and losses. Number size distributions based on mobility equivalent diameter obtained soon after launch with a Differential Mobility Particle Sizer showed lognormal distributions with an initial count median diameter (CMD) of 0.3 {mu}m and a geometric standard deviation, {sigma}{sub g} of about 2; the CMD was found to increase and {sigma}{sub g} decrease with time due to coagulation. Mass size distributions based on aerodynamic diameter were obtained for the first time with a Microorifice Uniform Deposit Impactor, which showed lognormal distributions with mass median aerodynamic diameters of about 0.5 {mu}m and an aerodynamic geometric standard deviation of about 2. Approximate methods for converting between number and mass distributions and between mobility and aerodynamic equivalent diameters are presented.

  6. Aerosol formation from high-velocity uranium drops: Comparison of number and mass distributions. Final report

    International Nuclear Information System (INIS)

    Rader, D.J.; Benson, D.A.

    1995-05-01

    This report presents the results of an experimental study of the aerosol produced by the combustion of high-velocity molten-uranium droplets produced by the simultaneous heating and electromagnetic launch of uranium wires. These tests are intended to simulate the reduction of high-velocity fragments into aerosol in high-explosive detonations or reactor accidents involving nuclear materials. As reported earlier, the resulting aerosol consists mainly of web-like chain agglomerates. A condensation nucleus counter was used to investigate the decay of the total particle concentration due to coagulation and losses. Number size distributions based on mobility equivalent diameter obtained soon after launch with a Differential Mobility Particle Sizer showed lognormal distributions with an initial count median diameter (CMD) of 0.3 μm and a geometric standard deviation, σ g of about 2; the CMD was found to increase and σ g decrease with time due to coagulation. Mass size distributions based on aerodynamic diameter were obtained for the first time with a Microorifice Uniform Deposit Impactor, which showed lognormal distributions with mass median aerodynamic diameters of about 0.5 μm and an aerodynamic geometric standard deviation of about 2. Approximate methods for converting between number and mass distributions and between mobility and aerodynamic equivalent diameters are presented

  7. Measurement of radioactive aerosols as an original indicator of atmospheric pollution in urban areas

    International Nuclear Information System (INIS)

    Le Petit, G.; Millies-Lacroix, J. C.

    1998-01-01

    The Service Radioanalyses, Chimie et Environnment (Departement Analyses Surveillance de l'Environnement) of the French Atomic Energy Commission, located in suburban Paris, has for many years been conducting atmospheric radioactivity measurements. Since 1994, the laboratory has been using high volume air samplers equipped with filters for the weekly collection of atmospheric aerosols at a mean rate of about 600 m 3 .h -1 . The polypropylene filters, with a collection efficiency in excess of 93%, are compacted after sampling. The atmospheric radioactivity is measured by HP Ge gamma spectrometry after decay of short-lived natural relationship products. A study conducted in 1996 shows good correlation between the evolution with time of some of the indicators routinely used by AIRPARIF, the organization in charge of monitoring the air quality in the Ile-de-France region, to measure atmospheric pollution in the Paris area (SO 2 , NO) and that related to radioactivity of terrestrial ( 210 Pb, 40 K) and anthropogenic ( 137 Cs) origin, as well as the amount of aerosols collected. Further, the distribution in time of the atmospheric radioactivity of cosmogenic origin ( 7 Be) shows a yearly evolution somewhat similar to that observed with ozone

  8. Measurement of radioactive aerosols as an original indicator of atmospheric pollution in urban areas

    International Nuclear Information System (INIS)

    Le Petit, G.; Millies-Lacroix, J.-C.; Simon, F.

    1998-01-01

    The Service Radioanalyses, Chimie et Environnement (Departement Analyses Surveillance de l'Environnement) of the French Atomic Energy Commission, located in suburban Paris, has for many years been conducting atmospheric radioactivity measurements. Since 1994, the laboratory has been using high volume air samplers equipped with filters for the weekly collection of atmospheric aerosols at a mean rate of about 600 m 3 .h -1 . The polypropylene filters, with a collection efficiency in excess of 93%, are compacted after sampling. The atmospheric radioactivity is measured by HP Ge gamma spectrometry after decay of short-lived natural relationship products. A study conducted in 1996 shows good correlation between the evolution with time of some of the indicators routinely used by AIRPARIF, the organization in charge of monitoring of the air quality in the Ile-de-France region, to measure atmospheric pollution in the Paris area (SO 2 , NO) and that related to radioactivity of terrestrial ( 210 Pb, 40 K) and anthropogenic ( 137 Cs) origin, as well as the amount of aerosols collected. Further, the distribution in time of the atmospheric radioactivity of cosmogenic origin ( 7 Be) shows a yearly evolution somewhat similar to that observed with ozone. (author). 16 refs., 21 figs., 1 tab

  9. Study of particle size distribution and formation mechanism of radioactive aerosols generated in high-energy neutron fields

    CERN Document Server

    Endo, A; Noguchi, H; Tanaka, S; Iida, T; Furuichi, S; Kanda, Y; Oki, Y

    2003-01-01

    The size distributions of sup 3 sup 8 Cl, sup 3 sup 9 Cl, sup 8 sup 2 Br and sup 8 sup 4 Br aerosols generated by irradiations of argon and krypton gases containing di-octyl phthalate (DOP) aerosols with 45 MeV and 65 MeV quasi-monoenergetic neutrons were measured in order to study the formation mechanism of radioactive particles in high energy radiation fields. The effects of the size distribution of the radioactive aerosols on the size of the added DOP aerosols, the energy of the neutrons and the kinds of nuclides were studied. The observed size distributions of the radioactive particles were explained by attachment of the radioactive atoms generated by the neutron-induced reactions to the DOP aerosols. (author)

  10. Meteorological and Land Surface Properties Impacting Sea Breeze Extent and Aerosol Distribution in a Dry Environment

    Science.gov (United States)

    Igel, Adele L.; van den Heever, Susan C.; Johnson, Jill S.

    2018-01-01

    The properties of sea breeze circulations are influenced by a variety of meteorological and geophysical factors that interact with one another. These circulations can redistribute aerosol particles and pollution and therefore can play an important role in local air quality, as well as impact remote sensing. In this study, we select 11 factors that have the potential to impact either the sea breeze circulation properties and/or the spatial distribution of aerosols. Simulations are run to identify which of the 11 factors have the largest influence on the sea breeze properties and aerosol concentrations and to subsequently understand the mean response of these variables to the selected factors. All simulations are designed to be representative of conditions in coastal sub tropical environments and are thus relatively dry, as such they do not support deep convection associated with the sea breeze front. For this dry sea breeze regime, we find that the background wind speed was the most influential factor for the sea breeze propagation, with the soil saturation fraction also being important. For the spatial aerosol distribution, the most important factors were the soil moisture, sea-air temperature difference, and the initial boundary layer height. The importance of these factors seems to be strongly tied to the development of the surface-based mixed layer both ahead of and behind the sea breeze front. This study highlights potential avenues for further research regarding sea breeze dynamics and the impact of sea breeze circulations on pollution dispersion and remote sensing algorithms.

  11. Aerosol Hygroscopicity Distribution and Mixing State Determined by Cloud Condensation Nuclei (CCN) Measurements

    Science.gov (United States)

    Su, H.; Rose, D.; Cheng, Y.; Gunthe, S. S.; Wiedensohler, A.; Andreae, M. O.; Pöschl, U.

    2009-12-01

    This paper presents, firstly the concept of hygroscopicity distribution and its application in the analysis of cloud condensation nuclei (CCN) measurement data. The cumulative particle hygroscopicity distribution function N(κ) is defined as the number concentration of particles with a hygroscopicity parameter, κ, smaller than a certain value of κ. Since the measured CCN (at supersaturation S) can be considered as those particles with κ larger than a certain value, the CCN efficiency spectra (activation curve) can be easily converted to N(κ) distributions. Unlike studies calculating only one hygroscopicity parameter from a CCN activation curve, the concept of N(κ) shows the usefulness of all points on the activation curve. Modeling studies of three assumed N(κ) distributions are used to illustrate the new concept N(κ) and how it is related to the size-resolved CCN measurements. Secondly, we discuss the aerosol mixing state information that can be obtained from the shape of N(κ). A case study is performed based on the CCN measurements during the CAREBEIJING 2006 campaign. In the campaign-averaged N(κ) distribution, most particles (>80%) lie in a mode with a geometric mean κ around 0.2-0.4, and an increasing trend in the mean κ is found as particle size increases. There seems to be another less hygroscopic mode but the κ resolution (depending on the size resolution) in the campaign is not high enough to interpret it. It is also clear that N(κ) is not a monodisperse distribution (implying an internal mixture of the aerosols). The dispersion parameter σg,κ, which is the geometric standard deviation of N(κ), can be used as an indicator for the aerosol mixing state. The indicator σg,κ shows good agreement with the soot mixing state measured by a volatility tandem differential mobility analyzer (VTDMA) during the CAREBEIJING 2006 campaign. The concept of N(κ) can be widely used to study aerosol mixing states, especially in the lab experiment where a

  12. A statistical analysis of North East Atlantic (submicron aerosol size distributions

    Directory of Open Access Journals (Sweden)

    M. Dall'Osto

    2011-12-01

    Full Text Available The Global Atmospheric Watch research station at Mace Head (Ireland offers the possibility to sample some of the cleanest air masses being imported into Europe as well as some of the most polluted being exported out of Europe. We present a statistical cluster analysis of the physical characteristics of aerosol size distributions in air ranging from the cleanest to the most polluted for the year 2008. Data coverage achieved was 75% throughout the year. By applying the Hartigan-Wong k-Means method, 12 clusters were identified as systematically occurring. These 12 clusters could be further combined into 4 categories with similar characteristics, namely: coastal nucleation category (occurring 21.3 % of the time, open ocean nucleation category (occurring 32.6% of the time, background clean marine category (occurring 26.1% of the time and anthropogenic category (occurring 20% of the time aerosol size distributions. The coastal nucleation category is characterised by a clear and dominant nucleation mode at sizes less than 10 nm while the open ocean nucleation category is characterised by a dominant Aitken mode between 15 nm and 50 nm. The background clean marine aerosol exhibited a clear bimodality in the sub-micron size distribution, with although it should be noted that either the Aitken mode or the accumulation mode may dominate the number concentration. However, peculiar background clean marine size distributions with coarser accumulation modes are also observed during winter months. By contrast, the continentally-influenced size distributions are generally more monomodal (accumulation, albeit with traces of bimodality. The open ocean category occurs more often during May, June and July, corresponding with the North East (NE Atlantic high biological period. Combined with the relatively high percentage frequency of occurrence (32.6%, this suggests that the marine biota is an important source of new nano aerosol particles in NE Atlantic Air.

  13. Impact of vegetation growth on urban surface temperature distribution

    International Nuclear Information System (INIS)

    Buyadi, S N A; Mohd, W M N W; Misni, A

    2014-01-01

    Earlier studies have indicated that, the temperature distribution in the urban area is significantly warmer than its surrounding suburban areas. The process of urbanization has created urban heat island (UHI). As a city expands, trees are cut down to accommodate commercial development, industrial areas, roads, and suburban growth. Trees or green areas normally play a vital role in mitigating the UHI effects especially in regulating high temperature in saturated urban areas. This study attempts to assess the effects of vegetation growth on land surface temperature (LST) distribution in urban areas. An area within the City of Shah Alam, Selangor has been selected as the study area. Land use/land cover and LST maps of two different dates are generated from Landsat 5 TM images of the year 1991 and 2009. Only five major land cover classes are considered in this study. Mono-window algorithm is used to generate the LST maps. Landsat 5 TM images are also used to generate the NDVI maps. Results from this study have shown that there are significant land use changes within the study area. Although the conversion of green areas into residential and commercial areas significantly increase the LST, matured trees will help to mitigate the effects of UHI

  14. Size distribution and hygroscopic properties of aerosol particles from dry-season biomass burning in Amazonia

    Directory of Open Access Journals (Sweden)

    J. Rissler

    2006-01-01

    Full Text Available Aerosol particle number size distributions and hygroscopic properties were measured at a pasture site in the southwestern Amazon region (Rondonia. The measurements were performed 11 September-14 November 2002 as part of LBA-SMOCC (Large scale Biosphere atmosphere experiment in Amazonia - SMOke aerosols, Clouds, rainfall and Climate, and cover the later part of the dry season (with heavy biomass burning, a transition period, and the onset of the wet period. Particle number size distributions were measured with a DMPS (Differential Mobility Particle Sizer, 3-850nm and an APS (Aerodynamic Particle Sizer, extending the distributions up to 3.3 µm in diameter. An H-TDMA (Hygroscopic Tandem Differential Mobility Analyzer measured the hygroscopic diameter growth factors (Gf at 90% relative humidity (RH, for particles with dry diameters (dp between 20-440 nm, and at several occasions RH scans (30-90% RH were performed for 165nm particles. These data provide the most extensive characterization of Amazonian biomass burning aerosol, with respect to particle number size distributions and hygroscopic properties, presented until now. The evolution of the convective boundary layer over the course of the day causes a distinct diel variation in the aerosol physical properties, which was used to get information about the properties of the aerosol at higher altitudes. The number size distributions averaged over the three defined time periods showed three modes; a nucleation mode with geometrical median diameters (GMD of ~12 nm, an Aitken mode (GMD=61-92 nm and an accumulation mode (GMD=128-190 nm. The two larger modes were shifted towards larger GMD with increasing influence from biomass burning. The hygroscopic growth at 90% RH revealed a somewhat external mixture with two groups of particles; here denoted nearly hydrophobic (Gf~1.09 for 100 nm particles and moderately hygroscopic (Gf~1.26. While the hygroscopic growth factors were surprisingly similar over the

  15. Urban Surface Temperature Reduction via the Urban Aerosol Direct Effect: A Remote Sensing and WRF Model Sensitivity Study

    Directory of Open Access Journals (Sweden)

    Menglin Jin

    2010-01-01

    Full Text Available The aerosol direct effect, namely, scattering and absorption of sunlight in the atmosphere, can lower surface temperature by reducing surface insolation. By combining National Aeronautics and Space Administration (NASA AERONET (AErosol RObotic NETwork observations in large cities with Weather Research and Forecasting (WRF model simulations, we find that the aerosol direct reduction of surface insolation ranges from 40–100Wm−2, depending on aerosol loading and land-atmosphere conditions. To elucidate the maximum possible effect, values are calculated using a radiative transfer model based on the top quartile of the multiyear instantaneous aerosol data observed by AERONET sites. As a result, surface skin temperature can be reduced by 1°C-2°C while 2-m surface air temperature reductions are generally on the order of 0.5°C–1°C.

  16. Determination of the particle size distribution of an aerosol using a diffusion battery

    International Nuclear Information System (INIS)

    Maigne, Jean-Pierre

    1974-02-01

    The principal methods for the treatment of concentration measurements both upstream and downstream of a diffusion battery are reviewed and discussed, the purpose of the measurements being the determination of the aerosol particle size distribution. It is then demonstrated that the resolution of the equations arising from the problem leads to the imposing of physical constraints on the distribution sought, these constraints being more and more restrictive with increasing experimental inaccuracies. An algorithm is proposed which provides an approximate solution to the system of equations, certain predetermined criteria, and the constraints imposed on the distribution being taken into account. (author)

  17. Aerosol and rainfall variability over the Indian monsoon region: distributions, trends and coupling

    Directory of Open Access Journals (Sweden)

    R. Gautam

    2009-09-01

    Full Text Available Aerosol solar absorption over the Indian monsoon region has a potential role of modulating the monsoon circulation and rainfall distribution as suggested by recent studies based on model simulations. Prior to the onset of the monsoon, northern India is influenced by significant dust transport that constitutes the bulk of the regional aerosol loading over the Gangetic-Himalayan region. In this paper, a multi-sensor characterization of the increasing pre-monsoon aerosol loading over northern India, in terms of their spatial, temporal and vertical distribution is presented. Aerosol transport from the northwestern arid regions into the Indo-Gangetic Plains and over the foothills of the Himalayas is found to be vertically extended to elevated altitudes (up to 5 km as observed from the space-borne lidar measurements (CALIPSO. In relation with the enhanced pre-monsoon aerosol loading and the associated solar absorption effects on tropospheric temperature anomalies, this paper investigates the monsoon rainfall variability over India in recent past decades from an observational viewpoint. It is found that the early summer monsoon rainfall over India is on the rise since 1950s, as indicated by historical rainfall data, with over 20% increase for the period 1950–2004. This large sustained increase in the early summer rainfall is led by the observed strengthening of the pre-monsoon tropospheric land-sea thermal gradient over the Indian monsoon region as indicated by microwave satellite measurements (MSU of tropospheric temperatures from 1979–2007. Combined analysis of changes in tropospheric temperatures and summer monsoon rainfall in the past three decades, suggest a future possibility of an emerging rainfall pattern of a wetter monsoon over South Asia in early summer followed by a drier period.

  18. Simultaneously combining AOD and multiple trace gas measurements to identify decadal changes in urban and biomass burning aerosols

    Science.gov (United States)

    Cohen, Jason

    2017-04-01

    This work presents a methodology by which to comprehensively analyze simultaneous tropospheric measurements of AOD and associated trace gasses. It then applies this methodology by focusing over the past 11 years (2006-2016) on one of the most rapidly changing regions of the troposphere: Eastern and Southeastern Asia. The specific work presented incorporates measurements of both aerosol and related gas phase tropospheric measurements across different spectral, spatial, temporal, and passive/active sensors and properties, including: MODIS, MISR, OMI, CALIOP, and others. This new characterization reveals a trio of new information, including a time-invariant urban signal, slowly-time-varying new-urbanization signal, and a rapidly time-varying biomass burning signal. Additionally, due to the different chemical properties of the various species analyzed, analyzing the different spatial domains of the resulting products allows for further information in terms of the amounts of aerosols produced both through primary emissions as well as secondary processing. The end result is a new characterization, in space, time, and magnitude, of both anthropogenic and biomass burning aerosols. These results are then used to drive an advanced modeling system including aerosol chemistry, physics, optics, and transport, and employing an aerosol routine based on multi-modal and both externally mixed and core-shell mixing. The resulting characterization in space, time, and quantity is analyzed and compared against AERONET, NOAA, and other ground networks, with the results comparing consistently to or better than present approaches which set up net emissions separately from urban and biomass burning products. Scientifically, new source regions of emissions are identified, some of which were previously non-urbanized or found to not contain any fire hotspots. This new approach is consistent with the underlying economic and development pathways of expanding urban areas and rapid economic growth

  19. Vertical distribution of Martian aerosols from SPICAM/Mars-Express limb observations

    Science.gov (United States)

    Fedorova, A.; Korablev, O.; Bertaux, J.-L.; Rodin, A.; Perrier, S.; Moroz, V. I.

    Limb spectroscopic observations provide invaluable information about vertical distribution of main atmospheric components in the Martian atmosphere, in particular vertical distribution and structure of aerosols, which play an important role in the heat balance of the planet. Only limited set of successful limb spectroscopic observations have been carried out on Mars so far, including those by MGS/TES spectrometer and Thermoscan and Auguste experiments of Phobos mission. Currently SPICAM instrument onboard Mars-Express spacecraft has accomplished several sequences of limb observations. First analysis of limb sounding data received by SPICAM IR and UV channels, which imply the presence of fine, deep, optically thin aerosol fraction extended over broad range of altitudes, is presented.

  20. Exploring Urban Taxi Drivers’ Activity Distribution Based on GPS Data

    Directory of Open Access Journals (Sweden)

    Xiaowei Hu

    2014-01-01

    Full Text Available With the rapid development of information communication technology and data mining technology, we can obtain taxi vehicle’s real time operation status through the large-scale taxi GPS trajectories data and explore the drivers’ activity distribution characteristics. Based on the 204 continuous hours of 3198 taxi vehicles’ operation data of Shenzhen, China, this paper analyzed the urban taxi driver’s activity distribution characteristics from different temporal and spatial levels. In the time level, we identified the difference with taxi daily operation pattern (weekday versus weekends, continuous time in one day, passengers in vehicle time, and taxi drivers’ operation frequency; in the space level, we explored the taxi driver’s searching pattern, including searching activity space distribution and the relationship between the pick-up locations and the drop-off locations. This research can be helpful for urban taxi drivers’ operation and behavior pattern identification, as well as the contribution to the geographical activity space analysis.

  1. Unattached fraction and the aerosol size distribution of the radon progeny in a natural cave and mine atmospheres

    International Nuclear Information System (INIS)

    Butterweck, G.; Porstendoerfer, J.; Reineking, A.; Kesten, J.

    1992-01-01

    Measurements of the activity size distribution of aerosol-attached radon progeny and the amount of unattached radon daughters have been performed in mine atmospheres and a tourist cave. During working hours a large number (10 5 -10 6 cm -3 ) of aerosol particles is generated in mines, mainly by diesel engines. The activity size distribution of these aerosol particles has smaller median diameters (AMAD about 200 nm) than the aged aerosol existing in the mine during non-working hours (AMAD about 350 nm). Strictly correlated to the aerosol concentration, the unattached fraction of the radon progeny, f p , in the tourist cave (3000 particles per cm 3 ) is higher (f p = 0.1) than in mines (f p 0.01) during working hours. This yields 1.4-2.5 times higher radiation dose conversion factors in the natural cave than in mines under working conditions. (author)

  2. Vertical distribution of aerosols over the Maritime Continent during El Niño

    Science.gov (United States)

    Blake Cohen, Jason; Loong Ng, Daniel Hui; Lun Lim, Alan Wei; Chua, Xin Rong

    2018-05-01

    The vertical distribution of aerosols over Southeast Asia, a critical factor impacting aerosol lifetime, radiative forcing, and precipitation, is examined for the 2006 post El Niño fire burning season. Combining these measurements with remotely sensed land, fire, and meteorological measurements, and fire plume modeling, we have reconfirmed that fire radiative power (FRP) is underestimated over Southeast Asia by MODIS measurements. These results are derived using a significantly different approach from other previously attempted approaches found in the literature. The horizontally constrained Maritime Continent's fire plume median height, using the maximum variance of satellite observed aerosol optical depth as the spatial and temporal constraint, is found to be 2.04 ± 1.52 km during the entirety of the 2006 El Niño fire season, and 2.19±1.50 km for October 2006. This is 0.83 km (0.98 km) higher than random sampling and all other past studies. Additionally, it is determined that 61 (+6-10) % of the bottom of the smoke plume and 83 (+8-11) % of the median of the smoke plume is in the free troposphere during the October maximum; while 49 (+7-9) % and 75 (+12-12) % of the total aerosol plume and the median of the aerosol plume, are correspondingly found in the free troposphere during the entire fire season. This vastly different vertical distribution will have impacts on aerosol lifetime and dispersal. Application of a simple plume rise model using measurements of fire properties underestimates the median plume height by 0.26 km over the entire fire season and 0.34 km over the maximum fire period. It is noted that the model underestimation over the bottom portions of the plume are much larger. The center of the plume can be reproduced when fire radiative power is increased by 20 % (with other parts of the plume ranging from an increase of 0 to 60 % depending on the portion of the plume and the length of the fire season considered). However, to reduce the biases

  3. Size distribution and ionic composition of marine summer aerosol at the continental Antarctic site Kohnen

    Science.gov (United States)

    Weller, Rolf; Legrand, Michel; Preunkert, Susanne

    2018-02-01

    We measured aerosol size distributions and conducted bulk and size-segregated aerosol sampling during two summer campaigns in January 2015 and January 2016 at the continental Antarctic station Kohnen (Dronning Maud Land). Physical and chemical aerosol properties differ conspicuously during the episodic impact of a distinctive low-pressure system in 2015 (LPS15) compared to the prevailing clear sky conditions. The approximately 3-day LPS15 located in the eastern Weddell Sea was associated with the following: marine boundary layer air mass intrusion; enhanced condensation particle concentrations (1400 ± 700 cm-3 compared to 250 ± 120 cm-3 under clear sky conditions; mean ± SD); the occurrence of a new particle formation event exhibiting a continuous growth of particle diameters (Dp) from 12 to 43 nm over 44 h (growth rate 0.6 nm h-1); peaking methane sulfonate (MS-), non-sea-salt sulfate (nss-SO42-), and Na+ concentrations (190 ng m-3 MS-, 137 ng m-3 nss-SO42-, and 53 ng m-3 Na+ compared to 24 ± 15, 107 ± 20, and 4.1 ± 2.2 ng m-3, respectively, during clear sky conditions); and finally an increased MS- / nss-SO42- mass ratio βMS of 0.4 up to 2.3 (0.21 ± 0.1 under clear sky conditions) comparable to typical values found at coastal Antarctic sites. Throughout the observation period a larger part of MS- could be found in super-micron aerosol compared to nss-SO42-, i.e., (10 ± 2) % by mass compared to (3.2 ± 2) %, respectively. On the whole, under clear sky conditions aged aerosol characterized by usually mono-modal size distributions around Dp = 60 nm was observed. Although our observations indicate that the sporadic impacts of coastal cyclones were associated with enhanced marine aerosol entry, aerosol deposition on-site during austral summer should be largely dominated by typical steady clear sky conditions.

  4. Measurement of an electronic cigarette aerosol size distribution during a puff

    Directory of Open Access Journals (Sweden)

    Belka Miloslav

    2017-01-01

    Full Text Available Electronic cigarettes (e-cigarettes have become very popular recently because they are marketed as a healthier alternative to tobacco smoking and as a useful tool to smoking cessation. E-cigarettes use a heating element to create an aerosol from a solution usually consisting of propylene glycol, glycerol, and nicotine. Despite the wide spread of e-cigarettes, information about aerosol size distributions is rather sparse. This can be caused by the relative newness of e-cigarettes and by the difficulty of the measurements, in which one has to deal with high concentration aerosol containing volatile compounds. Therefore, we assembled an experimental setup for size measurements of e-cigarette aerosol in conjunction with a piston based machine in order to simulate a typical puff. A TSI scanning mobility particle sizer 3936 was employed to provide information about particle concentrations and sizes. An e-cigarette commercially available on the Czech Republic market was tested and the results were compared with a conventional tobacco cigarette. The particles emitted from the e-cigarette were smaller than those of the conventional cigarette having a CMD of 150 and 200 nm. However, the total concentration of particles from e-cigarette was higher.

  5. Measurement of an electronic cigarette aerosol size distribution during a puff

    Science.gov (United States)

    Belka, Miloslav; Lizal, Frantisek; Jedelsky, Jan; Jicha, Miroslav; Pospisil, Jiri

    Electronic cigarettes (e-cigarettes) have become very popular recently because they are marketed as a healthier alternative to tobacco smoking and as a useful tool to smoking cessation. E-cigarettes use a heating element to create an aerosol from a solution usually consisting of propylene glycol, glycerol, and nicotine. Despite the wide spread of e-cigarettes, information about aerosol size distributions is rather sparse. This can be caused by the relative newness of e-cigarettes and by the difficulty of the measurements, in which one has to deal with high concentration aerosol containing volatile compounds. Therefore, we assembled an experimental setup for size measurements of e-cigarette aerosol in conjunction with a piston based machine in order to simulate a typical puff. A TSI scanning mobility particle sizer 3936 was employed to provide information about particle concentrations and sizes. An e-cigarette commercially available on the Czech Republic market was tested and the results were compared with a conventional tobacco cigarette. The particles emitted from the e-cigarette were smaller than those of the conventional cigarette having a CMD of 150 and 200 nm. However, the total concentration of particles from e-cigarette was higher.

  6. Key Role of Nitrate in Phase Transitions of Urban Particles: Implications of Important Reactive Surfaces for Secondary Aerosol Formation

    Science.gov (United States)

    Sun, Jiaxing; Liu, Lei; Xu, Liang; Wang, Yuanyuan; Wu, Zhijun; Hu, Min; Shi, Zongbo; Li, Yongjie; Zhang, Xiaoye; Chen, Jianmin; Li, Weijun

    2018-01-01

    Ammonium sulfate (AS) and ammonium nitrate (AN) are key components of urban fine particles. Both field and model studies showed that heterogeneous reactions of SO2, NO2, and NH3 on wet aerosols accelerated the haze formation in northern China. However, little is known on phase transitions of AS-AN containing haze particles. Here hygroscopic properties of laboratory-generated AS-AN particles and individual particles collected during haze events in an urban site were investigated using an individual particle hygroscopicity system. AS-AN particles showed a two-stage deliquescence at mutual deliquescence relative humidity (MDRH) and full deliquescence relative humidity (DRH) and three physical states: solid before MDRH, solid-aqueous between MDRH and DRH, and aqueous after DRH. During hydration, urban haze particles displayed a solid core and aqueous shell at RH = 60-80% and aqueous phase at RH > 80%. Most particles were in aqueous phase at RH > 50% during dehydration. Our results show that AS content in individual particles determines their DRH and AN content determines their MDRH. AN content increase can reduce MDRH, which indicates occurrence of aqueous shell at lower RH. The humidity-dependent phase transitions of nitrate-abundant urban particles are important to provide reactive surfaces of secondary aerosol formation in the polluted air.

  7. Inverse problem for particle size distributions of atmospheric aerosols using stochastic particle swarm optimization

    International Nuclear Information System (INIS)

    Yuan Yuan; Yi Hongliang; Shuai Yong; Wang Fuqiang; Tan Heping

    2010-01-01

    As a part of resolving optical properties in atmosphere radiative transfer calculations, this paper focuses on obtaining aerosol optical thicknesses (AOTs) in the visible and near infrared wave band through indirect method by gleaning the values of aerosol particle size distribution parameters. Although various inverse techniques have been applied to obtain values for these parameters, we choose a stochastic particle swarm optimization (SPSO) algorithm to perform an inverse calculation. Computational performances of different inverse methods are investigated and the influence of swarm size on the inverse problem of computation particles is examined. Next, computational efficiencies of various particle size distributions and the influences of the measured errors on computational accuracy are compared. Finally, we recover particle size distributions for atmospheric aerosols over Beijing using the measured AOT data (at wavelengths λ=0.400, 0.690, 0.870, and 1.020 μm) obtained from AERONET at different times and then calculate other AOT values for this band based on the inverse results. With calculations agreeing with measured data, the SPSO algorithm shows good practicability.

  8. Size distributions and chemical properties of aerosol at Ny Ålesund, Svalbard

    Science.gov (United States)

    Covert, David S.; Heintzenberg, Jost

    Physical and chemical parameters of the arctic aerosol were investigated at Ny Ålesund, Svalbard, in March and April 1989 in connection with the third Arctic Gas and Aerosol Project (AGASP III). The number size distribution of the particles was measured over the range of 0.02-1.0 μm. Filter samples were analysed for elemental composition and two integral chemical properties, hygroscopic growth and volatility, were measured. Along with the latter measurements, the distribution of these properties at specific particle sizes, i.e. the degree of internal mixing, was determined. Both clean, marine conditions and "arctic haze" episodes were included in the series of measurements. The number size distribution indicated that the aerosol was well aged based on its narrowness and the relative low concentration of nuclei mode particles. It had a number mode at 0.22 μm diameter and geometric standard deviation of 1.4. Generally the particles exhibited uniform hygroscopic growth properties, i.e. they were largely internally mixed. The growth factor was 1.45 at 90% relative humidity. Approximately 40% of the overall particulate mass was volatile at a temperature of 50°C. The volatile fraction varied form particle to particle, i.e. the particles were externally mixed with respect to volatility.

  9. Urbanization effects on sediment and trace metals distribution in an urban winter pond (Netanya, Israel)

    NARCIS (Netherlands)

    Zohar, I.; Teutsch, N.; Levin, N.; Mackin, G.; de Stigter, H.; Bookman, R.

    2017-01-01

    PurposeThis paper aims to elucidate urban development-induced processes affecting the sediment and the distribution of contaminating metals in a seasonal pond located in the highly populated Israeli Coastal Plain. The paper demonstrates how an integrated approach, including geochemical,

  10. Quantifying dust plume formation and aerosol size distribution during the Saharan Mineral Dust Experiment in North Africa

    KAUST Repository

    Khan, Basit Ali; Stenchikov, Georgiy L.; Weinzierl, Bernadett; Kalenderski, Stoitchko; Osipov, Sergey

    2015-01-01

    outflow are key mechanisms that form a surface--detached aerosol plume over the ocean. Comparisons of simulated dust size distributions with airplane and ground--based observations are generally good, but suggest that more detailed treatment

  11. Temporal characteristics of inhalable mercury and arsenic aerosols in the urban atmosphere in southern Taiwan

    Science.gov (United States)

    Tsai, Ying I.; Kuo, Su-Ching; Lin, Yi-Hsuan

    Urban aerosol samples for PM 10 and PM 2.5 were collected during summer (August) and winter (December) 2000 in southern Taiwan (Tainan City) to demonstrate the temporal variations of Hg and As in particulate matter (PM). The mean mass concentrations with standard deviations were 80.0±26.8 μg m -3 for PM 10 and 50.6±16.6 μg m -3 for PM 2.5. The average PM 2.5/PM 10 mass ratio for the two periods combined was 63%, indicating that fine particles were a large portion of PM 10. Particulate samples of Hg and As were analyzed within 2 days following sampling and weighing, because of the highly volatile nature of PM Hg and As. The average Hg and As values in PM 10, PM 2.5 and PM 2.5-10 in summer were significantly lower than those in winter. PM 2.5 Hg constituted 0.34 to 5.8 ng m -3 and PM 2.5-10 Hg 0.05 to 3.1 ng m -3. PM 2.5 As constituted 1.09 to 9.51 ng m -3 and PM 2.5-10 As 0.18 to 4.14 ng m -3. In summer and winter PM 10, the Hg contents showed regular daily variation, with the higher values at daytime and lower values at nighttime, indicating conversion of gaseous Hg to the particulate phase by reaction with atmospheric oxidants under strong solar radiation during the daytime in both summer and winter. PM As behaved similar to Hg in the summer, but in the winter higher concentrations were observed during the nighttime than during the daytime, implying that the stable temperature inversion during winter nighttime caused the accumulation of PM As near the ground. In summer, SE-WSW winds carried As from an As-emitting fossil power plant to the sample area. In a similar vein, NE-WNW winter winds contributed to aerosol Hg, especially in PM 2.5, originating from a waste incinerator located NW of Tainan City.

  12. Sustainable practices in urban freight distribution in Bilbao

    Directory of Open Access Journals (Sweden)

    Esther Alvarez

    2011-10-01

    Full Text Available Purpose: The objective of the present study is to select some feasible and sustainable logistic practices in order to improve the urban freight distribution in Bilbao city. Design/methodology/approach: After a thorough literature review and a benchmarking, Analytic Hierarchy Process (AHP techniques were used in order to support the decision making processes in order to select the most interesting practices. The criteria used for this selection were based on four factors: (1 improvement of the city freight distribution, (2 implementation possibility, (3 short and medium term applicability and (4 impact on the citizens of Bilbao. Findings: The paper identifies some specific problems that must be faced during the last stage of the logistics chain, where products are usually delivered to final customers in the urban environment. Research limitations/implications: Not all good urban freight distribution practices can be applied universally to all types of towns. Therefore, it is necessary to design some practices specifically to each particular city according to the physical characteristics of the city, the companies’ motivation and the citizens’ habits. Practical implications: All the agents involved in the city freight distribution should be aware of the benefits and problems that their actions cause. Originality/value: This study was carried out from a wide perspective that included researchers, logistics operators and local authorities.

  13. Distribution of sulfur aerosol precursors in the SPCZ released by continuous volcanic degassing at Ambrym, Vanuatu

    Science.gov (United States)

    Lefèvre, Jérôme; Menkes, Christophe; Bani, Philipson; Marchesiello, Patrick; Curci, Gabriele; Grell, Georg A.; Frouin, Robert

    2016-08-01

    The Melanesian Volcanic Arc (MVA) emits about 12 kT d- 1 of sulfur dioxide (SO2) to the atmosphere from continuous passive (non-explosive) volcanic degassing, which contributes 20% of the global SO2 emission from volcanoes. Here we assess, from up-to-date and long-term observations, the SO2 emission of the Ambrym volcano, one of the dominant volcanoes in the MVA, and we investigate its role as sulfate precursor on the regional distribution of aerosols, using both satellite observations and model results at 1° × 1° spatial resolution from WRF-Chem/GOCART. Without considering aerosol forcing on clouds, our model parameterizations for convection, vertical mixing and cloud properties provide a reliable chemical weather representation, making possible a cross-examination of model solution and observations. This preliminary work enables the identification of biases and limitations affecting both the model (missing sources) and satellite sensors and algorithms (for aerosol detection and classification) and leads to the implementation of improved transport and aerosol processes in the modeling system. On the one hand, the model confirms a 50% underestimation of SO2 emissions due to satellite swath sampling of the Ozone Monitoring Instrument (OMI), consistent with field studies. The OMI irregular sampling also produces a level of noise that impairs its monitoring capacity during short-term volcanic events. On the other hand, the model reveals a large sensitivity on aerosol composition and Aerosol Optical Depth (AOD) due to choices of both the source function in WRF-Chem and size parameters for sea-salt in FlexAOD, the post-processor used to compute offline the simulated AOD. We then proceed to diagnosing the role of SO2 volcanic emission in the regional aerosol composition. The model shows that both dynamics and cloud properties associated with the South Pacific Convergence Zone (SPCZ) have a large influence on the oxidation of SO2 and on the transport pathways of

  14. Preliminary study of 7Be, 137Cs and 131I activity concentration distribution rule in Beijing aerosol

    International Nuclear Information System (INIS)

    Fan Yuanqing; Wang Shilian; Zhang Xinjun; Li Qi; Jia Huaimao; Zhao Yungang; Chen Zhanying; Chang Yinzhong; Liu Shujiang; Li Huijuan

    2013-01-01

    The process of aerosol sampling and measuring of Beijing Radionuclide Station and Beijing Radionuclide Laboratory of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) International Monitoring System (IMS) was described. Long time aerosol monitoring data of the station and the laboratory were analyzed through statistic method and the characteristic and rule of the concentration distribution of nuclides 7 Be, 137 Cs and 131 I were obtained. The foundation was formed for further studying the rule of the radionuclide distribution in atmosphere. (authors)

  15. Estimation of the volatility distribution of organic aerosol combining thermodenuder and isothermal dilution measurements

    Science.gov (United States)

    Louvaris, Evangelos E.; Karnezi, Eleni; Kostenidou, Evangelia; Kaltsonoudis, Christos; Pandis, Spyros N.

    2017-10-01

    A method is developed following the work of Grieshop et al. (2009) for the determination of the organic aerosol (OA) volatility distribution combining thermodenuder (TD) and isothermal dilution measurements. The approach was tested in experiments that were conducted in a smog chamber using organic aerosol (OA) produced during meat charbroiling. A TD was operated at temperatures ranging from 25 to 250 °C with a 14 s centerline residence time coupled to a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and a scanning mobility particle sizer (SMPS). In parallel, a dilution chamber filled with clean air was used to dilute isothermally the aerosol of the larger chamber by approximately a factor of 10. The OA mass fraction remaining was measured as a function of temperature in the TD and as a function of time in the isothermal dilution chamber. These two sets of measurements were used together to estimate the volatility distribution of the OA and its effective vaporization enthalpy and accommodation coefficient. In the isothermal dilution experiments approximately 20 % of the OA evaporated within 15 min. Almost all the OA evaporated in the TD at approximately 200 °C. The resulting volatility distributions suggested that around 60-75 % of the cooking OA (COA) at concentrations around 500 µg m-3 consisted of low-volatility organic compounds (LVOCs), 20-30 % of semivolatile organic compounds (SVOCs), and around 10 % of intermediate-volatility organic compounds (IVOCs). The estimated effective vaporization enthalpy of COA was 100 ± 20 kJ mol-1 and the effective accommodation coefficient was 0.06-0.07. Addition of the dilution measurements to the TD data results in a lower uncertainty of the estimated vaporization enthalpy as well as the SVOC content of the OA.

  16. Estimation of the volatility distribution of organic aerosol combining thermodenuder and isothermal dilution measurements

    Directory of Open Access Journals (Sweden)

    E. E. Louvaris

    2017-10-01

    Full Text Available A method is developed following the work of Grieshop et al. (2009 for the determination of the organic aerosol (OA volatility distribution combining thermodenuder (TD and isothermal dilution measurements. The approach was tested in experiments that were conducted in a smog chamber using organic aerosol (OA produced during meat charbroiling. A TD was operated at temperatures ranging from 25 to 250 °C with a 14 s centerline residence time coupled to a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS and a scanning mobility particle sizer (SMPS. In parallel, a dilution chamber filled with clean air was used to dilute isothermally the aerosol of the larger chamber by approximately a factor of 10. The OA mass fraction remaining was measured as a function of temperature in the TD and as a function of time in the isothermal dilution chamber. These two sets of measurements were used together to estimate the volatility distribution of the OA and its effective vaporization enthalpy and accommodation coefficient. In the isothermal dilution experiments approximately 20 % of the OA evaporated within 15 min. Almost all the OA evaporated in the TD at approximately 200 °C. The resulting volatility distributions suggested that around 60–75 % of the cooking OA (COA at concentrations around 500 µg m−3 consisted of low-volatility organic compounds (LVOCs, 20–30 % of semivolatile organic compounds (SVOCs, and around 10 % of intermediate-volatility organic compounds (IVOCs. The estimated effective vaporization enthalpy of COA was 100 ± 20 kJ mol−1 and the effective accommodation coefficient was 0.06–0.07. Addition of the dilution measurements to the TD data results in a lower uncertainty of the estimated vaporization enthalpy as well as the SVOC content of the OA.

  17. Charge distribution on plutonium-containing aerosols produced in mixed-oxide reactor fuel fabrication and the laboratory

    International Nuclear Information System (INIS)

    Yeh, H.C.; Newton, G.J.; Teague, S.V.

    1976-01-01

    The inhalation toxicity of potentially toxic aerosols may be affected by the electrostatic charge on the particles. Charge may influence the deposition site during inhalation and therefore its subsequent clearance and dose patterns. The electrostatic charge distributions on plutonium-containing aerosols were measured with a miniature, parallel plate, aerosol electrical mobility spectrometer. Two aerosols were studied: a laboratory-produced 238 PuO 2 aerosol (15.8 Ci/g) and a plutonium mixed-oxide aerosol (PU-MOX, natural UO 2 plus PuO 2 , 0.02 Ci/g) formed during industrial centerless grinding of mixed-oxide reactor fuel pellets. Plutonium-238 dioxide particles produced in the laboratory exhibited a small net positive charge within a few minutes after passing through a 85 Kr discharger due to alpha particle emission removal of valence electrons. PU-MOX aerosols produced during centerless grinding showed a charge distribution essentially in Boltzmann equilibrium. The gross alpha aerosol concentrations (960-1200 nCi/l) within the glove box were sufficient to provide high ion concentrations capable of discharging the charge induced by mechanical and/or nuclear decay processes

  18. Contribution of bacteria-like particles to PM2.5 aerosol in urban and rural environments

    Science.gov (United States)

    Wolf, R.; El-Haddad, I.; Slowik, J. G.; Dällenbach, K.; Bruns, E.; Vasilescu, J.; Baltensperger, U.; Prévôt, A. S. H.

    2017-07-01

    We report highly time-resolved estimates of airborne bacteria-like particle concentrations in ambient aerosol using an Aerodyne aerosol mass spectrometer (AMS). AMS measurements with a newly developed PM2.5 and the standard (PM1) aerodynamic lens were performed at an urban background site (Zurich) and at a rural site (Payerne) in Switzerland. Positive matrix factorization using the multilinear engine (ME-2) implementation was used to estimate the contribution of bacteria-like particles to non-refractory organic aerosol. The success of the method was evaluated by a size-resolved analysis of the organic mass and the analysis of single particle mass spectra, which were detected with a light scattering system integrated into the AMS. Use of the PM2.5 aerodynamic lens increased measured bacteria-like concentrations, supporting the analysis method. However, at all sites, the low concentrations of this component suggest that airborne bacteria constitute a minor fraction of non-refractory PM2.5 organic aerosol mass. Estimated average mass concentrations were below 0.1 μg/m3 and relative contributions were lower than 2% at both sites. During rainfall periods, concentrations of the bacteria-like component increased considerably reaching a short-time maximum of approximately 2 μg/m3 at the Payerne site in summer.

  19. Source apportionment of organic compounds in Berlin using positive matrix factorization - assessing the impact of biogenic aerosol and biomass burning on urban particulate matter.

    Science.gov (United States)

    Wagener, Sandra; Langner, Marcel; Hansen, Ute; Moriske, Heinz-Jörn; Endlicher, Wilfried R

    2012-10-01

    Source apportionment of 13 organic compounds, elemental carbon and organic carbon of ambient PM(10) and PM(1) was performed with positive matrix factorization (PMF). Samples were collected at three sites characterized by different vegetation influences in Berlin, Germany in 2010. The aim was to determine organic, mainly biogenic sources and their impact on urban aerosol collected in a densely populated region. A 6-factor solution provided the best data fit for both PM-fractions, allowing the sources isoprene- and α-pinene-derived secondary organic aerosol (SOA), bio primary, primarily attributable to fungal spores, bio/urban primary including plant fragments in PM(10) and cooking and traffic emissions in PM(1), biomass burning and combustion fossil to be identified. With mean concentrations up to 2.6 μg Cm(-3), biomass burning dominated the organic fraction in cooler months. Concentrations for α-pinene-derived SOA exceeded isoprene-derived concentrations. Estimated secondary organic carbon contributions to total organic carbon (OC) were between 7% and 42% in PM(10) and between 11% and 60% in PM(1), which is slightly lower than observed for US- or Asian cities. Primary biogenic emissions reached up to 33% of OC in the PM(10)-fraction in the late summer and autumn months. Temperature-dependence was found for both SOA-factors, correlations with ozone and mix depth only for the α-pinene-derived SOA-factor. Latter indicated input of α-pinene from the borders, highlighting differences in the origin of the precursors of both factors. Most factors were regionally distributed. High regional distribution was found to be associated with stronger influence of ambient parameters and higher concentrations at the background station. A significant contribution of biogenic emissions and biomass burning to urban organic aerosol could be stated. This indicates a considerable impact on PM concentrations also in cities in a densely populated area, and should draw the attention

  20. Distribution of Costs and Profits in Urban Development

    DEFF Research Database (Denmark)

    Christensen, Finn Kjær; Sørensen, Michael Tophøj

    2009-01-01

    Most countries have a system - procedures and tools - for foreseeable, clear and fair distribution of costs and profits in urban development. However, the distribution of profits and costs between the municipality and the developers /landowners is in Denmark rather fragmented and not very...... transparent as the distribution is regulated throughout the whole planning and environmental regulation system. Furthermore, development agreements – an “old” tool in many countries and an efficient tool to distribute profits and costs between the public and private sector – have only recently become possible...... in Denmark, and only under some special circumstances. This paper aims to clarify how costs and profits are distributed between the municipality and the developers /landowners in Denmark. The paper analyses how the Danish planning and environmental regulation system handles this issue. Based on the analysis...

  1. Lead isotopic characterization of respirable urban aerosols and related sources, Santiago-Chile

    International Nuclear Information System (INIS)

    Diaz, M; Kawashita, K; Antinao, J.L

    2001-01-01

    Santiago de Chile is located in a poorly ventilated valley at 33 o 30' latitude south at an altitude of 550m. Local climate is semi-arid with mean annual rainfall below 350mm. The atmospheric particles constitute one of the main factors of urban air pollution in the city. Morphological characterization of airborne particles of Santiago done by Scanning Electron Microscopy showed the presence of three groups of particles: crystalline. spherical and agglomerate particles. The crystalline shapes originated in geologic sources have perfectly defined crystallographic parameters. The agglomerated shapes are formed by organic material and submicrometrical mineral particles derived from combustion of fossil fuel and the spherical shapes are products of metallurgical activities. Some of them could been associated with the wear of motorcars. Samples of aerosols. sediments and leaded petrol of different distributors were collected. Aerosols were sampled in two sites of Santiago: the Movil monitoring station, at east of the city, and Parque O'Higgins monitoring station in downtown. These two monitoring stations belong to the MACAM network. Sediments of Mapocho, Maipo, San Francisco and Zanjon de la Aguada rivers and two samples from Disputada and Merceditas ores were studied. All the samples have been measured for their 206 Pb/ 204 Pb, 207 Pb/ 204 Pb and 208 Pb/ 204 Pb ratios. The experimental chemical procedures of sample dissolution and Pb separation by anion exchange chromatography were developed in the Sernageomin clean laboratory of Santiago de Chile. The isotopic measurements were made using a VG-Sector isotope ratio mass spectrometer fitted with a thermal ion source, multi Faraday collector and Daly collector of the Isotopic Geology Laboratory in the Universidade Federal de Rio Grande do Sul, Brazil. The measurements were corrected using NBS 981 and 982 standards. Isotopic results plotted in a 208 Pb/ 204 Pb versus 206 Pb/ 204 Pb diagram and in a 207 Pb/ 204 Pb versus

  2. An inverse modeling procedure to determine particle growth and nucleation rates from measured aerosol size distributions

    Directory of Open Access Journals (Sweden)

    B. Verheggen

    2006-01-01

    Full Text Available Classical nucleation theory is unable to explain the ubiquity of nucleation events observed in the atmosphere. This shows a need for an empirical determination of the nucleation rate. Here we present a novel inverse modeling procedure to determine particle nucleation and growth rates based on consecutive measurements of the aerosol size distribution. The particle growth rate is determined by regression analysis of the measured change in the aerosol size distribution over time, taking into account the effects of processes such as coagulation, deposition and/or dilution. This allows the growth rate to be determined with a higher time-resolution than can be deduced from inspecting contour plots ('banana-plots''. Knowing the growth rate as a function of time enables the evaluation of the time of nucleation of measured particles of a certain size. The nucleation rate is then obtained by integrating the particle losses from time of measurement to time of nucleation. The regression analysis can also be used to determine or verify the optimum value of other parameters of interest, such as the wall loss or coagulation rate constants. As an example, the method is applied to smog chamber measurements. This program offers a powerful interpretive tool to study empirical aerosol population dynamics in general, and nucleation and growth in particular.

  3. Sustainable practices in urban freight distribution in Bilbao

    OpenAIRE

    Esther Alvarez; Alberto de la Calle

    2011-01-01

    Purpose: The objective of the present study is to select some feasible and sustainable logistic practices in order to improve the urban freight distribution in Bilbao city. Design/methodology/approach: After a thorough literature review and a benchmarking, Analytic Hierarchy Process (AHP) techniques were used in order to support the decision making processes in order to select the most interesting practices. The criteria used for this selection were based on four factors: (1) improvement of t...

  4. Spatial and seasonal distribution of Arctic aerosols observed by the CALIOP satellite instrument (2006–2012

    Directory of Open Access Journals (Sweden)

    M. Di Pierro

    2013-07-01

    Full Text Available We use retrievals of aerosol extinction from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP onboard the CALIPSO satellite to examine the vertical, horizontal and temporal variability of tropospheric Arctic aerosols during the period 2006–2012. We develop an empirical method that takes into account the difference in sensitivity between daytime and nighttime retrievals over the Arctic. Comparisons of the retrieved aerosol extinction to in situ measurements at Barrow (Alaska and Alert (Canada show that CALIOP reproduces the observed seasonal cycle and magnitude of surface aerosols to within 25 %. In the free troposphere, we find that daytime CALIOP retrievals will only detect the strongest aerosol haze events, as demonstrated by a comparison to aircraft measurements obtained during NASA's ARCTAS mission during April 2008. This leads to a systematic underestimate of the column aerosol optical depth by a factor of 2–10. However, when the CALIOP sensitivity threshold is applied to aircraft observations, we find that CALIOP reproduces in situ observations to within 20% and captures the vertical profile of extinction over the Alaskan Arctic. Comparisons with the ground-based high spectral resolution lidar (HSRL at Eureka, Canada, show that CALIOP and HSRL capture the evolution of the aerosol backscatter vertical distribution from winter to spring, but a quantitative comparison is inconclusive as the retrieved HSRL backscatter appears to overestimate in situ observations by a factor of 2 at all altitudes. In the High Arctic (>70° N near the surface (−1, followed by a sharp decline and a minimum in May–September (1–4 Mm−1, thus providing the first pan-Arctic view of Arctic haze seasonality. The European and Asian Arctic sectors display the highest wintertime extinctions, while the Atlantic sector is the cleanest. Over the Low Arctic (60–70° N near the surface, CALIOP extinctions reach a maximum over land in summer due to

  5. Elemental and organic carbon in aerosols over urbanized coastal region (southern Baltic Sea, Gdynia).

    Science.gov (United States)

    Lewandowska, Anita; Falkowska, Lucyna; Murawiec, Dominika; Pryputniewicz, Dorota; Burska, Dorota; Bełdowska, Magdalena

    2010-09-15

    Studies on PM 10, total particulate matter (TSP), elemental carbon (EC) and organic carbon (OC) concentrations were carried out in the Polish coastal zone of the Baltic Sea, in urbanized Gdynia. The interaction between the land, the air and the sea was clearly observed. The highest concentrations of PM 10, TSP and both carbon fractions were noted in the air masses moving from southern and western Poland and Europe. The EC was generally of primary origin and its contribution to TSP and PM 10 mass was on average 2.3% and 3.7% respectively. Under low wind speed conditions local sources (traffic and industry) influenced increases in elemental carbon and PM 10 concentrations in Gdynia. Elemental carbon demonstrated a pronounced weekly cycle, yielding minimum values at the weekend and maximum values on Thursdays. The role of harbors and ship yards in creating high EC concentrations was clearly observed. Concentration of organic carbon was ten times higher than that of elemental carbon, and the average OC contribution to PM 10 mass was very high (31.6%). An inverse situation was observed when air masses were transported from over the Atlantic Ocean, the North Sea and the Baltic Sea. These clean air masses were characterized by the lowest concentrations of all analysed compounds. Obtained results for organic and elemental carbon fluxes showed that atmospheric aerosols can be treated, along with water run-off, as a carbon source for the coastal waters of the Baltic Sea. The enrichment of surface water was more effective in the case of organic carbon (0.27+/-0.19 mmol m(-2) d(-1)). Elemental carbon fluxes were one order of magnitude smaller, on average 0.03+/-0.04 mmol m(-2) d(-1). We suggest that in some situations atmospheric carbon input can explain up to 18% of total carbon fluxes into the Baltic coastal waters. Copyright 2010 Elsevier B.V. All rights reserved.

  6. Mechanisms of desorption of 134Cs and 85Sr aerosols deposited on urban surfaces

    International Nuclear Information System (INIS)

    Real, J.; Persin, F.; Camarasa-Claret, C.

    2002-01-01

    The radioactive isotopes of cesium and strontium may be deposited on urban surfaces in the case of an accidental atmospheric discharge from a nuclear facility and thus imply a health hazard. In order to handle the decontamination of these surfaces, we have carried out experiments under controlled conditions on tiles and concrete and we have studied the physical and chemical mechanisms at the solid-liquid interface. The deposition of radionuclides was carried out in the form of aerosols indicating an accidental source term. Their desorption by rainwater is low in all cases, of the order of 5-6% for cesium for any material and 29 and 12% for strontium on tile and concrete, respectively. The low desorption values of cesium may be explained by the strong bonding that occurs with the silicates constituting the tile due to virtually irreversible processes of exchange of ions and by the formation of insoluble complexes with the C-S-H gel of concrete. The strontium-tile bonds are weaker, while strontium precipitates with the carbonates of concrete in the form of SrCO 3 . In view of these characteristics, washing solutions with high concentrations of chloride and oxalate of ammonium chosen for their ion-exchanging and sequestering properties were tested on these surfaces. The desorption of cesium improved strongly since it reached 70% on tile and 90% on concrete after 24 h of contact, which is consistent with our knowledge of the bonds between this element and the surfaces. Strontium, given the greater complexity of physical and chemical forms that it may take is less well desorbed. The ammonium chloride improves the desorption (50% and 40%, for tile and concrete, respectively) but the oxalate, while it does not affect desorption on the tiles, decreases that on the concrete since by strongly etching the concrete, it causes the release of carbonate ions that precipitate with strontium

  7. Marine aerosol distribution and variability over the pristine Southern Indian Ocean

    Science.gov (United States)

    Mallet, Paul-Étienne; Pujol, Olivier; Brioude, Jérôme; Evan, Stéphanie; Jensen, Andrew

    2018-06-01

    This paper presents an 8-year (2005-2012 inclusive) study of the marine aerosol distribution and variability over the Southern Indian Ocean, precisely in the area { 10 °S - 40 °S ; 50 °E - 110 °E } which has been identified as one of the most pristine regions of the globe. A large dataset consisting of satellite data (POLDER, CALIOP), AERONET measurements at Saint-Denis (French Réunion Island) and model reanalysis (MACC), has been used. In spite of a positive bias of about 0.05 between the AOD (aerosol optical depth) given by POLDER and MACC on one hand and the AOD measured by AERONET on the other, consistent results for aerosol distribution and variability over the area considered have been obtained. First, aerosols are mainly confined below 2km asl (above sea level) and are dominated by sea salt, especially in the center of the area of interest, with AOD ≤ 0 . 1. This zone is the most pristine and is associated with the position of the Mascarene anticyclone. There, the direct radiative effect is assessed around - 9 Wm-2 at the top of the atmosphere and probability density functions of the AOD s are leptokurtic lognormal functions without any significant seasonal variation. It is also suggested that the Madden-Jullian oscillation impacts sea salt emissions in the northern part of the area considered by modifying the state of the ocean surface. Finally, this area is surrounded in the northeast and the southwest by seasonal Australian and South African intrusions (AOD > 0.1) ; throughout the year, the ITCZ seems to limit continental contaminations from Asia. Due to the long period of time considered (almost a decade), this paper completes and strengthens results of studies based on observations performed during previous specific field campaigns.

  8. Hourly elemental concentrations in PM2.5 aerosols sampled simultaneously at urban background and road site during SAPUSS – diurnal variations and PMF receptor modelling

    Directory of Open Access Journals (Sweden)

    M. Dall'Osto

    2013-04-01

    Full Text Available Hourly-resolved aerosol chemical speciation data can be a highly powerful tool to determine the source origin of atmospheric pollutants in urban environments. Aerosol mass concentrations of seventeen elements (Na, Mg, Al, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Pb were obtained by time (1 h and size (PM2.5 particulate matter 2.5 mass fraction simultaneously measured at the UB and RS sites: (1 the regional aerosol sources impact both monitoring sites at similar concentrations regardless their different ventilation conditions; (2 by contrast, local industrial aerosol plumes associated with shipping oil combustion and smelters activities have a higher impact on the more ventilated UB site; (3 a unique source of Pb-Cl (associated with combustion emissions is found to be the major (82% source of fine Cl in the urban agglomerate; (4 the mean diurnal variation of PM2.5 primary traffic non-exhaust brake dust (Fe-Cu suggests that this source is mainly emitted and not resuspended, whereas PM2.5 urban dust (Ca is found mainly resuspended by both traffic vortex and sea breeze; (5 urban dust (Ca is found the aerosol source most affected by land wetness, reduced by a factor of eight during rainy days and suggesting that wet roads may be a solution for reducing urban dust concentrations.

  9. Aerosol Size Distributions During ACE-Asia: Retrievals From Optical Thickness and Comparisons With In-situ Measurements

    Science.gov (United States)

    Kuzmanoski, M.; Box, M.; Box, G. P.; Schmidt, B.; Russell, P. B.; Redemann, J.; Livingston, J. M.; Wang, J.; Flagan, R. C.; Seinfeld, J. H.

    2002-12-01

    As part of the ACE-Asia experiment, conducted off the coast of China, Korea and Japan in spring 2001, measurements of aerosol physical, chemical and radiative characteristics were performed aboard the Twin Otter aircraft. Of particular importance for this paper were spectral measurements of aerosol optical thickness obtained at 13 discrete wavelengths, within 354-1558 nm wavelength range, using the AATS-14 sunphotometer. Spectral aerosol optical thickness can be used to obtain information about particle size distribution. In this paper, we use sunphotometer measurements to retrieve size distribution of aerosols during ACE-Asia. We focus on four cases in which layers influenced by different air masses were identified. Aerosol optical thickness of each layer was inverted using two different techniques - constrained linear inversion and multimodal. In the constrained linear inversion algorithm no assumption about the mathematical form of the distribution to be retrieved is made. Conversely, the multimodal technique assumes that aerosol size distribution is represented as a linear combination of few lognormal modes with predefined values of mode radii and geometric standard deviations. Amplitudes of modes are varied to obtain best fit of sum of optical thicknesses due to individual modes to sunphotometer measurements. In this paper we compare the results of these two retrieval methods. In addition, we present comparisons of retrieved size distributions with in situ measurements taken using an aerodynamic particle sizer and differential mobility analyzer system aboard the Twin Otter aircraft.

  10. Annual cycle of size-resolved organic aerosol characterization in an urbanized desert environment

    Science.gov (United States)

    Cahill, Thomas M.

    2013-06-01

    Studies of size-resolved organic speciation of aerosols are still relatively rare and are generally only conducted over short durations. However, size-resolved organic data can both suggest possible sources of the aerosols and identify the human exposure to the chemicals since different aerosol sizes have different lung capture efficiencies. The objective of this study was to conduct size-resolved organic aerosol speciation for a calendar year in Phoenix, Arizona to determine the seasonal variations in both chemical concentrations and size profiles. The results showed large seasonal differences in combustion pollutants where the highest concentrations were observed in winter. Summertime aerosols have a greater proportion of biological compounds (e.g. sugars and fatty acids) and the biological compounds represent the largest fraction of the organic compounds detected. These results suggest that standard organic carbon (OC) measurements might be heavily influenced by primary biological compounds particularly if the samples are PM10 and TSP samples. Several large dust storms did not significantly alter the organic aerosol profile since Phoenix resides in a dusty desert environment, so the soil and plant tracer of trehalose was almost always present. The aerosol size profiles showed that PAHs were generally most abundant in the smallest aerosol size fractions, which are most likely to be captured by the lung, while the biological compounds were almost exclusively found in the coarse size fraction.

  11. Online Simulations of Global Aerosol Distributions in the NASA GEOS-4 Model and Comparisons to Satellite and Ground-Based Aerosol Optical Depth

    Science.gov (United States)

    Colarco, Peter; daSilva, Arlindo; Chin, Mian; Diehl, Thomas

    2010-01-01

    We have implemented a module for tropospheric aerosols (GO CART) online in the NASA Goddard Earth Observing System version 4 model and simulated global aerosol distributions for the period 2000-2006. The new online system offers several advantages over the previous offline version, providing a platform for aerosol data assimilation, aerosol-chemistry-climate interaction studies, and short-range chemical weather forecasting and climate prediction. We introduce as well a methodology for sampling model output consistently with satellite aerosol optical thickness (AOT) retrievals to facilitate model-satellite comparison. Our results are similar to the offline GOCART model and to the models participating in the AeroCom intercomparison. The simulated AOT has similar seasonal and regional variability and magnitude to Aerosol Robotic Network (AERONET), Moderate Resolution Imaging Spectroradiometer, and Multiangle Imaging Spectroradiometer observations. The model AOT and Angstrom parameter are consistently low relative to AERONET in biomass-burning-dominated regions, where emissions appear to be underestimated, consistent with the results of the offline GOCART model. In contrast, the model AOT is biased high in sulfate-dominated regions of North America and Europe. Our model-satellite comparison methodology shows that diurnal variability in aerosol loading is unimportant compared to sampling the model where the satellite has cloud-free observations, particularly in sulfate-dominated regions. Simulated sea salt burden and optical thickness are high by a factor of 2-3 relative to other models, and agreement between model and satellite over-ocean AOT is improved by reducing the model sea salt burden by a factor of 2. The best agreement in both AOT magnitude and variability occurs immediately downwind of the Saharan dust plume.

  12. Source apportionment of size and time resolved trace elements and organic aerosols from an urban courtyard site in Switzerland

    Directory of Open Access Journals (Sweden)

    A. Richard

    2011-09-01

    Full Text Available Time and size resolved data of trace elements were obtained from measurements with a rotating drum impactor (RDI and subsequent X-ray fluorescence spectrometry. Trace elements can act as indicators for the identification of sources of particulate matter <10 μm (PM10 in ambient air. Receptor modeling was performed with positive matrix factorization (PMF for trace element data from an urban background site in Zürich, Switzerland. Eight different sources were identified for the three examined size ranges (PM1−0.1, PM2.5−1 and PM10−2.5: secondary sulfate, wood combustion, fire works, road traffic, mineral dust, de-icing salt, industrial and local anthropogenic activities. The major component was secondary sulfate for the smallest size range; the road traffic factor was found in all three size ranges. This trace element analysis is complemented with data from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (AMS, assessing the PM1 fraction of organic aerosols. A separate PMF analysis revealed three factors related to three of the sources found with the RDI: oxygenated organic aerosol (OOA, related to inorganic secondary sulfate, hydrocarbon-like organic aerosol (HOA, related to road traffic and biomass burning organic aerosol (BBOA, explaining 60 %, 22 % and 17 % of total measured organics, respectively. Since different compounds are used for the source classification, a higher percentage of the ambient PM10 mass concentration can be apportioned to sources by the combination of both methods.

  13. Oxidative potential of size-fractionated atmospheric aerosol in urban and rural sites across Europe.

    Science.gov (United States)

    Shafer, Martin M; Hemming, Jocelyn D C; Antkiewicz, Dagmara S; Schauer, James J

    2016-07-18

    In this study we applied several assays, an in vitro rat alveolar macrophage model, a chemical ROS probe (DTT, dithiothreitol), and cytokine induction (TNFα) to examine relationships between PM-induced generation of reactive oxygen species (ROS) and PM composition, using a unique set of size-resolved PM samples obtained from urban and rural environments across Europe. From April-July 2012, we collected PM from roadside canyon, roadside motorway, and background urban sites in each of six European cities and from three rural sites spanning the continent. A Hi-Vol sampler was used to collect PM in three size classes (PM>7, PM7-3, PM3) and PM was characterized for total elements, and oxidative activity quantified in unfiltered and filtered PM extracts. We measured a remarkable uniformity in air concentrations of ROS and especially DTT activity across the continent. Only a 4-fold difference was documented for DTT across the urban sites and a similar variance was documented for ROS, implying that chemical drivers of oxidative activity are relatively similar between sites. The ROS and DTT specific activity was greater at urban background sites (and also rural sites) than at urban canyon locations. PM3 dominated the size distribution of both ROS activity (86% of total) and DTT activity (76% of total), reflecting both the large contribution of PM3 to total PM mass levels and importantly the higher specific oxidative activity of the PM3 in comparison with the larger particles. The soluble fraction of total activity was very high for DTT (94%) as well as for ROS (64%) in the PM3. However in the larger PM size fractions the contributions of the insoluble components became increasingly significant. The dominance of the insoluble PM drivers of activity was particularly evident in the TNFα data, where the insoluble contribution to cytokine production could be 100-fold greater than that from soluble components. ROS and DTT activity were strongly correlated in the PM3 (r = 0

  14. Particle size distribution of radioactive aerosols after the Fukushima and the Chernobyl accidents.

    Science.gov (United States)

    Malá, Helena; Rulík, Petr; Bečková, Vera; Mihalík, Ján; Slezáková, Miriam

    2013-12-01

    Following the Fukushima accident, a series of aerosol samples were taken between 24th March and 13th April 2011 by cascade impactors in the Czech Republic to obtain the size distribution of (131)I, (134)Cs, (137)Cs, and (7)Be aerosols. All distributions could be considered monomodal. The arithmetic means of the activity median aerodynamic diameters (AMADs) for artificial radionuclides and for (7)Be were 0.43 and 0.41 μm with GDSs 3.6 and 3.0, respectively. The time course of the AMADs of (134)Cs, (137)Cs and (7)Be in the sampled period showed a slight decrease at a significance level of 0.05, whereas the AMAD pertaining to (131)I increased at a significance level of 0.1. Results obtained after the Fukushima accident were compared with results obtained after the Chernobyl accident. The radionuclides released during the Chernobyl accident for which we determined the AMAD fell into two categories: refractory radionuclides ((140)Ba, (140)La (141)Ce, (144)Ce, (95)Zr and (95)Nb) and volatile radionuclides ((134)Cs, (137)Cs, (103)Ru, (106)Ru, (131)I, and (132)Te). The AMAD of the refractory radionuclides was approximately 3 times higher than the AMAD of the volatile radionuclides; nevertheless, the size distributions for volatile radionuclides having a mean AMAD value of 0.51 μm were very close to the distributions after the Fukushima accident. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Variability of carbonaceous aerosols in remote, rural, urban and industrial environments in Spain: implications for air quality policy

    Science.gov (United States)

    Querol, X.; Alastuey, A.; Viana, M.; Moreno, T.; Reche, C.; Minguillón, M. C.; Ripoll, A.; Pandolfi, M.; Amato, F.; Karanasiou, A.; Pérez, N.; Pey, J.; Cusack, M.; Vázquez, R.; Plana, F.; Dall'Osto, M.; de la Rosa, J.; Sánchez de la Campa, A.; Fernández-Camacho, R.; Rodríguez, S.; Pio, C.; Alados-Arboledas, L.; Titos, G.; Artíñano, B.; Salvador, P.; García Dos Santos, S.; Fernández Patier, R.

    2013-07-01

    We interpret here the variability of levels of carbonaceous aerosols based on a 12 yr database from 78 monitoring stations across Spain specially compiled for this article. Data did not evidence any spatial trends of carbonaceous aerosols across the country. Conversely, results show marked differences in average concentrations from the cleanest, most remote sites (around 1 μg m-3 of non-mineral carbon (nmC), mostly made of organic carbon (OC) with very little elemental carbon (EC), around 0.1 μg m-3; OC / EC = 12-15), to the highly polluted major cities (8-10 μg m-3 of nmC; 3-4 μg m-3 of EC; 4-5 μg m-3 of OC; OC / EC = 1-2). Thus, urban (and very specific industrial) pollution was found to markedly increase levels of carbonaceous aerosols in Spain, with much lower impact of biomass burning and of biogenic emissions. Correlations between yearly averaged OC / EC and EC concentrations adjust very well to a potential equation (OC = 3.37 EC0.326, R2 = 0.8). A similar equation is obtained when including average concentrations obtained at other European sites (OC = 3.60EC0.491, R2 = 0.7). A clear seasonal variability in OC and EC concentrations was detected. Both OC and EC concentrations were higher during winter at the traffic and urban sites, but OC increased during the warmer months at the rural sites. Hourly equivalent black carbon (EBC) concentrations at urban sites accurately depict road traffic contributions, varying with distance from road, traffic volume and density, mixing-layer height and wind speed. Weekday urban rush-hour EBC peaks are mimicked by concentrations of primary gaseous emissions from road traffic, whereas a single midday peak is characteristic of remote and rural sites. Decreasing annual trends for carbonaceous aerosols were observed between 1999 and 2011 at a large number of stations, probably reflecting the impact of the EURO4 and EURO5 standards in reducing the diesel PM emissions. This has resulted in some cases in an increasing trend for

  16. Global Distribution of Solid Ammonium Sulfate Aerosols and their Climate Impact Acting as Ice Nuclei

    Science.gov (United States)

    Zhou, C.; Penner, J.

    2017-12-01

    Laboratory experiments show that liquid ammonium sulfate particles effloresce when RHw is below 34% to become solid and dissolve when RHw is above 79%. Solid ammonium sulfate aerosols can act as heterogeneous ice nuclei particles (INPs) to form ice particles in deposition mode when the relative humidity over ice is above 120%. In this study we used the coupled IMPACT/CAM5 model to track the efflorescence and deliquescence processes of ammonium sulfate. Results show that about 20% of the total simulated pure sulfate aerosol mass is in the solid state and is mainly distributed in the northern hemisphere (NH) from 50 hPa to 200 hPa. When these solid ammonium sulfate aerosols are allowed to act as ice nuclei particles, they act to increase the ice water path in the NH and reduce ice water path in the tropics. The addition of these particles leads to a positive net radiative effect at the TOA ranging from 0.5-0.9 W/m2 depending on the amounts of other ice nuclei particles (e.g., dust, soot) used in the ice nucleation process. The short-term climate feedback shows that the ITCZ shifts northwards and precipitation increases in the NH. There is also an average warming of 0.05-0.1 K near the surface (at 2 meter) in the NH which is most obvious in the Arctic region.

  17. Atmospheric aerosols size distribution properties in winter and pre-monsoon over western Indian Thar Desert location

    Energy Technology Data Exchange (ETDEWEB)

    Panwar, Chhagan, E-mail: chhaganpanwar@gmail.com; Vyas, B. M. [Department of Physics, M.L. Sukhadia University, Udaipur-313001 (India)

    2016-05-06

    The first ever experimental results over Indian Thar Desert region concerning to height integrated aerosols size distribution function in particles size ranging between 0.09 to 2 µm such as, aerosols columnar size distribution (CSD), effective radius (R{sub eff}), integrated content of total aerosols (N{sub t}), columnar content of accumulation and coarse size aerosols particles concentration (N{sub a}) (size < 0.5 µm) and (N{sub c}) (size between 0.5 to 2 µm) have been described specifically during winter (a stable weather condition and intense anthropogenic pollution activity period) and pre-monsoon (intense dust storms of natural mineral aerosols as well as unstable atmospheric weather condition period) at Jaisalmer (26.90°N, 69.90°E, 220 m above surface level (asl)) located in central Thar desert vicinity of western Indian site. The CSD and various derived other aerosols size parameters are retrieved from their average spectral characteristics of Aerosol Optical Thickness (AOT) from UV to Infrared wavelength spectrum measured from Multi-Wavelength solar Radiometer (MWR). The natures of CSD are, in general, bio-modal character, instead of uniformly distributed character and power law distributions. The observed primary peaks in CSD plots are seen around about 10{sup 13} m{sup 2} μm{sup −1} at radius range 0.09-0.20 µm during both the seasons. But, in winter months, secondary peaks of relatively lower CSD values of 10{sup 10} to 10{sup 11} m{sup 2}/μm{sup −1} occur within a lower radius size range 0.4 to 0.6 µm. In contrast to this, while in dust dominated and hot season, the dominated secondary maxima of the higher CSD of about 10{sup 12} m{sup 2}μm{sup −3} is found of bigger aerosols size particles in a rage of 0.6 to 1.0 µm which is clearly demonstrating the characteristics of higher aerosols laden of bigger size aerosols in summer months relative to their prevailed lower aerosols loading of smaller size aerosols particles (0

  18. Chemical, optical and radiative characteristics of aerosols during haze episodes of winter in the North China Plain

    Science.gov (United States)

    Ding, Jing; Zhang, Yufen; Han, Suqin; Xiao, Zhimei; Wang, Jiao; Feng, Yinchang

    2018-05-01

    Aerosol and water vapor radiative forcings, shortwave atmospheric heating rates and longwave atmospheric cooling rates were determined based on in situ physical and chemical measurements of aerosol, associated with the Mie theory and a radiative transfer model, LOWTRAN7, during the two haze episodes in the winter of 2013 in Tianjin, China. The aerosol types considered in LOWTRAN7 included rural, urban, marine, desert and custom aerosols. The default ratio of the absorption coefficient to the extinction coefficient for urban aerosol in LOWTRAN7 was approximately double of those found in this work, implying the weaker absorption ability of aerosols in the North China Plain (NCP). Moreover, the aerosol is assumed to be evenly distributed below 1 km of planetary boundary layer (PBL) on hazy days in LOWTRAN7. If the default urban aerosol optical properties and extinction profile in LOWTRAN7 is employed directly, a larger energy imbalance between the atmosphere and surface is generated and the warming effect of the aerosol is magnified. Hence, modified urban aerosol optical properties were established to replace the corresponding parameters' database in LOWTRAN7. The aerosol extinction profiles were obtained based on a 255-m meteorological tower and observed results from the studies about Tianjin. In the NCP, the aerosol had little impact on atmospheric counter radiation. The water vapor is the crucial factor that affects atmospheric counter radiation. Both modified high shortwave heating rates and longwave cooling rates occur near the surface due to the abundance of aerosol and water vapor. The modified net atmospheric heating rate near the surface is 1.2 K d-1 on hazy days and 0.3 K d-1 on non-hazy days. Compared with the default urban aerosol optical properties and its vertical distribution in LOWTRAN7, the feedback effect of the modified urban aerosol on the boundary layer may not necessarily result in a stable lower atmosphere, but depends on the aerosol light

  19. Physical and Chemical Aerosol Properties At An Urban and A Rural Site During An Episode of Strong Photochemical Activity During Escompte

    Science.gov (United States)

    van Dingenen, R.; Putaud, J. P.; dell'Acqua, A.; Martins-Dos Santos, S.; Viidanoja, J.; Raes, F.

    During the ESCOMPTE campaign (10 June to 14 July, 2001), JRC mobile laboratories for aerosol physical and chemical measurements were deployed at two ground-based sites: Vallon Dol, located at the Northern edge of the Marseille agglomeration and Vi- non, a rural site about 80 km North-East of Marseille. Both sites were equipped with on-line instrumentation for number size distributions in the diameter size range 6nm to 10µm (10 minute time resolution), equivalent black carbon (15 minute time reso- lution), major anions and cations (15 minute time resolution). Time-integrated filter sampling at each site with a time resolution of 6-12 hours was performed with 2 sets of virtual impactors, separating the fine and coarse aerosol fraction. One set, loaded with quartz filters, was analyzed off-line using the `evolved gas analysis` technique for organic and elemental carbon. The second set, loaded with paper filters, was analyzed for dust (by ashing) and ionic composition. On top of the common instrumentation, the urban site was additionally performing on-line PM10 measurements (TEOM with sample equilibration system, 10 minute time resolution) and, during intensive obser- vation periods (IOP), size-segregated sampling with a 8 stage low-pressure Berner im- pactor (6-12 hours time resolution). In this presentation we will focus on data obtained during the second IOP (20-6 to 26-6). During this episode, the sea-breeze transported Marseille pollution plume was clearly observed at the Vinon rural site. Comparison of the aerosol properties at both sites will allow to evaluate the processes that contribute to the (trans)formation of particulate matter in the particular conditions of a marine air mass, mixed with local pollution and undergoing strong photochemical processes during in-land transport.

  20. Variability of aerosol, gaseous pollutants and meteorological characteristics associated with continental, urban and marine air masses at the SW Atlantic coast of Iberia

    Science.gov (United States)

    Diesch, J.-M.; Drewnick, F.; Zorn, S. R.; von der Weiden-Reinmüller, S.-L.; Martinez, M.; Borrmann, S.

    2011-12-01

    Measurements of the ambient aerosol were performed at the Southern coast of Spain, within the framework of the DOMINO (Diel Oxidant Mechanisms In relation to Nitrogen Oxides) project. The field campaign took place from 20 November until 9 December 2008 at the atmospheric research station "El Arenosillo" (37°5'47.76" N, 6°44'6.94" W). As the monitoring station is located at the interface between a natural park, industrial cities (Huelva, Seville) and the Atlantic Ocean a variety of physical and chemical parameters of aerosols and gas phase could be characterized in dependency on the origin of air masses. Backwards trajectories were examined and compared with local meteorology to classify characteristic air mass types for several source regions. Aerosol number and mass as well as polycyclic aromatic hydrocarbons and black carbon concentrations were measured in PM1 and size distributions were registered covering a size range from 7 nm up to 32 μm. The chemical composition of the non-refractory submicron aerosol was measured by means of an Aerosol Mass Spectrometer (Aerodyne HR-ToF-AMS). Gas phase analyzers monitored various trace gases (O3, SO2, NO, NO2, CO2) and a weather station provided meteorological parameters. Lowest average submicron particle mass and number concentrations were found in air masses arriving from the Atlantic Ocean with values around 2 μg m-3 and 1000 cm-3. These mass concentrations were about two to four times lower than the values recorded in air masses of continental and urban origins. For some species PM1-fractions in marine air were significantly larger than in air masses originating from Huelva, a closely located city with extensive industrial activities. The largest fraction of sulfate (54%) was detected in marine air masses and was to a high degree not neutralized. In addition small concentrations of methanesulfonic acid (MSA), a product of biogenic dimethyl sulfate (DMS) emissions could be identified in the particle phase. In all

  1. The evolution of biomass-burning aerosol size distributions due to coagulation: dependence on fire and meteorological details and parameterization

    Directory of Open Access Journals (Sweden)

    K. M. Sakamoto

    2016-06-01

    Full Text Available Biomass-burning aerosols have a significant effect on global and regional aerosol climate forcings. To model the magnitude of these effects accurately requires knowledge of the size distribution of the emitted and evolving aerosol particles. Current biomass-burning inventories do not include size distributions, and global and regional models generally assume a fixed size distribution from all biomass-burning emissions. However, biomass-burning size distributions evolve in the plume due to coagulation and net organic aerosol (OA evaporation or formation, and the plume processes occur on spacial scales smaller than global/regional-model grid boxes. The extent of this size-distribution evolution is dependent on a variety of factors relating to the emission source and atmospheric conditions. Therefore, accurately accounting for biomass-burning aerosol size in global models requires an effective aerosol size distribution that accounts for this sub-grid evolution and can be derived from available emission-inventory and meteorological parameters. In this paper, we perform a detailed investigation of the effects of coagulation on the aerosol size distribution in biomass-burning plumes. We compare the effect of coagulation to that of OA evaporation and formation. We develop coagulation-only parameterizations for effective biomass-burning size distributions using the SAM-TOMAS large-eddy simulation plume model. For the most-sophisticated parameterization, we use the Gaussian Emulation Machine for Sensitivity Analysis (GEM-SA to build a parameterization of the aged size distribution based on the SAM-TOMAS output and seven inputs: emission median dry diameter, emission distribution modal width, mass emissions flux, fire area, mean boundary-layer wind speed, plume mixing depth, and time/distance since emission. This parameterization was tested against an independent set of SAM-TOMAS simulations and yields R2 values of 0.83 and 0.89 for Dpm and modal width

  2. The evolution of biomass-burning aerosol size distributions due to coagulation: dependence on fire and meteorological details and parameterization

    Science.gov (United States)

    Sakamoto, Kimiko M.; Laing, James R.; Stevens, Robin G.; Jaffe, Daniel A.; Pierce, Jeffrey R.

    2016-06-01

    Biomass-burning aerosols have a significant effect on global and regional aerosol climate forcings. To model the magnitude of these effects accurately requires knowledge of the size distribution of the emitted and evolving aerosol particles. Current biomass-burning inventories do not include size distributions, and global and regional models generally assume a fixed size distribution from all biomass-burning emissions. However, biomass-burning size distributions evolve in the plume due to coagulation and net organic aerosol (OA) evaporation or formation, and the plume processes occur on spacial scales smaller than global/regional-model grid boxes. The extent of this size-distribution evolution is dependent on a variety of factors relating to the emission source and atmospheric conditions. Therefore, accurately accounting for biomass-burning aerosol size in global models requires an effective aerosol size distribution that accounts for this sub-grid evolution and can be derived from available emission-inventory and meteorological parameters. In this paper, we perform a detailed investigation of the effects of coagulation on the aerosol size distribution in biomass-burning plumes. We compare the effect of coagulation to that of OA evaporation and formation. We develop coagulation-only parameterizations for effective biomass-burning size distributions using the SAM-TOMAS large-eddy simulation plume model. For the most-sophisticated parameterization, we use the Gaussian Emulation Machine for Sensitivity Analysis (GEM-SA) to build a parameterization of the aged size distribution based on the SAM-TOMAS output and seven inputs: emission median dry diameter, emission distribution modal width, mass emissions flux, fire area, mean boundary-layer wind speed, plume mixing depth, and time/distance since emission. This parameterization was tested against an independent set of SAM-TOMAS simulations and yields R2 values of 0.83 and 0.89 for Dpm and modal width, respectively. The

  3. Partitioning phase preference for secondary organic aerosol in an urban atmosphere

    Science.gov (United States)

    Chang, Wayne Li-Wen

    Secondary organic aerosol (SOA) comprises a significant portion of atmospheric particular matter (PM). The impact of PM on both human health and global climate has long been recognized. Despite its importance, there are still many unanswered questions regarding the formation and evolution of SOA in the atmosphere. This study uses a modeling approach to understand the preferred partitioning behavior of SOA species into aqueous or organic condensed phases. More specifically, this work uses statistical analyses of approximately 24,000 data values for each variable from a state-of-the-art 3-D airshed model. Spatial and temporal distributions of fractions of SOA residing in the aqueous phase (fAQ) in the South Coast Air Basin of California are presented. Typical values of fAQ within the basin near the surface range from 5 to 80%. Results show that the distribution of fAQ values is inversely proportional to the total SOA loading. Further analysis accounting for various meteorological parameters indicates that large fAQ values are the results of aqueous-phase SOA insensitivity to the ambient conditions; while organic-phase SOA concentrations are dramatically reduced under unfavorable SOA formation conditions, aqueous-phase SOA level remains relatively unchanged, thus increasing fAQ at low SOA loading. Diurnal variations of fAQ near the surface are also observed: it tends to be larger during daytime hours than nighttime hours. When examining the vertical gradient of fAQ, largest values are found at heights above the surface layer. In summary, one must consider SOA in both organic and aqueous phases for proper regional and global SOA budget estimation.

  4. Simulation of concentration distribution of urban particles under wind

    Science.gov (United States)

    Chen, Yanghou; Yang, Hangsheng

    2018-02-01

    The concentration of particulate matter in the air is too high, which seriously affects people’s health. The concentration of particles in densely populated towns is also high. Understanding the distribution of particles in the air helps to remove them passively. The concentration distribution of particles in urban streets is simulated by using the FLUENT software. The simulation analysis based on Discrete Phase Modelling (DPM) of FLUENT. Simulation results show that the distribution of the particles is caused by different layout of buildings. And it is pointed out that in the windward area of the building and the leeward sides of the high-rise building are the areas with high concentration of particles. Understanding the concentration of particles in different areas is also helpful for people to avoid and reduce the concentration of particles in high concentration areas.

  5. Urban freight distribution: council warehouses & freight by rail

    Directory of Open Access Journals (Sweden)

    Aleksander SŁADKOWSKI

    2014-10-01

    Full Text Available Rail is the one of the highly underused form of freight transportation in the European Union. Majority of the freightage are distributed by trucks and HGVs. With new regulations and socio-environmental concerns urban logistics is facing a new challenge which can be tackled using innovative transport mechanisms and streamline operations. This article sheds light on a system which integrates freight distribution via metro lines in the closest vicinity of the customer, use of council warehouses and further innovative transport mechanisms for final delivery. This system uses existing infrastructure effectively without impacting its surroundings and triggers the reduction of polluting carriers. This system offers the option of immediate implementation which will enable EU to compete with a global freight distribution market.

  6. The response of a simulated mesoscale convective system to increased aerosol pollution: Part I: Precipitation intensity, distribution, and efficiency

    Science.gov (United States)

    Clavner, Michal; Cotton, William R.; van den Heever, Susan C.; Saleeby, Stephen M.; Pierce, Jeffery R.

    2018-01-01

    Mesoscale Convective Systems (MCSs) are important contributors to rainfall in the High Plains of the United States and elsewhere in the world. It is therefore of interest to understand how different aerosols serving as cloud condensation nuclei (CCN) may impact the total amount, rates and spatial distribution of precipitation produced by MCSs. In this study, different aerosol concentrations and their effects on precipitation produced by an MCS are examined by simulating the 8 May 2009 "Super-Derecho" MCS using the Regional Atmospheric Modeling System (RAMS), a cloud-resolving model (CRM) with sophisticated aerosol and microphysical parameterizations. Three simulations were conducted that differed only in the initial concentration, spatial distribution, and chemical composition of aerosols. Aerosol fields were derived from the output of GEOS-Chem, a 3D chemical transport numerical model. Results from the RAMS simulations show that the total domain precipitation was not significantly affected by variations in aerosol concentrations, however, the pollution aerosols altered the precipitation characteristics. The more polluted simulations exhibited higher precipitation rates, higher bulk precipitation efficiency, a larger area with heavier precipitation, and a smaller area with lighter precipitation. These differences arose as a result of aerosols enhancing precipitation in the convective region of the MCS while suppressing precipitation from the MCS's stratiform-anvil. In the convective region, several processes likely contributed to an increase of precipitation. First, owing to the very humid environment of this storm, the enhanced amount of cloud water available to be collected overwhelmed the reduction in precipitation efficiency associated with the aerosol-induced production of smaller droplets which led to a net increase in the conversion of cloud droplets to precipitation. Second, higher aerosol concentrations led to invigoration of convective updrafts which

  7. Hourly elemental concentrations in PM2.5 aerosols sampled simultaneously at urban background and road site during SAPUSS - diurnal variations and PMF receptor modelling

    Science.gov (United States)

    Dall'Osto, M.; Querol, X.; Amato, F.; Karanasiou, A.; Lucarelli, F.; Nava, S.; Calzolai, G.; Chiari, M.

    2013-04-01

    Hourly-resolved aerosol chemical speciation data can be a highly powerful tool to determine the source origin of atmospheric pollutants in urban environments. Aerosol mass concentrations of seventeen elements (Na, Mg, Al, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Pb) were obtained by time (1 h) and size (PM2.5 particulate matter Spain) during September-October 2010: an urban background site (UB) and a street canyon traffic road site (RS). Elements related to primary non-exhaust traffic emission (Fe, Cu), dust resuspension (Ca) and anthropogenic Cl were found enhanced at the RS, whereas industrial related trace metals (Zn, Pb, Mn) were found at higher concentrations at the more ventilated UB site. When receptor modelling was performed with positive matrix factorization (PMF), nine different aerosol sources were identified at both sites: three types of regional aerosols (regional sulphate (S) - 27%, biomass burning (K) - 5%, sea salt (Na-Mg) - 17%), three types of dust aerosols (soil dust (Al-Ti) - 17%, urban crustal dust (Ca) - 6%, and primary traffic non-exhaust brake dust (Fe-Cu) - 7%), and three types of industrial aerosol plumes-like events (shipping oil combustion (V-Ni) - 17%, industrial smelters (Zn-Mn) - 3%, and industrial combustion (Pb-Cl) - 5%, percentages presented are average source contributions to the total elemental mass measured). The validity of the PMF solution of the PIXE data is supported by very good correlations with external single particle mass spectrometry measurements. Some important conclusions can be drawn about the PM2.5 mass fraction simultaneously measured at the UB and RS sites: (1) the regional aerosol sources impact both monitoring sites at similar concentrations regardless their different ventilation conditions; (2) by contrast, local industrial aerosol plumes associated with shipping oil combustion and smelters activities have a higher impact on the more ventilated UB site; (3) a unique source of Pb-Cl (associated with

  8. Improvement of the CULTEX® exposure technology by radial distribution of the test aerosol.

    Science.gov (United States)

    Aufderheide, Michaela; Heller, Wolf-Dieter; Krischenowski, Olaf; Möhle, Niklas; Hochrainer, Dieter

    2017-07-05

    The exposure of cellular based systems cultivated on microporous membranes at the air-liquid interface (ALI) has been accepted as an appropriate approach to simulate the exposure of cells of the respiratory tract to native airborne substances. The efficiency of such an exposure procedure with regard to stability and reproducibility depends on the optimal design at the interface between the cellular test system and the exposure technique. The actual exposure systems favor the dynamic guidance of the airborne substances to the surface of the cells in specially designed exposure devices. Two module types, based on a linear or radial feed of the test atmosphere to the test system, were used for these studies. In our technical history, the development started with the linear designed version, the CULTEX ® glass modules, fulfilling basic requirements for running ALI exposure studies (Mohr and Durst, 2005). The instability in the distribution of different atmospheres to the cells caused us to create a new exposure module, characterized by a stable and reproducible radial guidance of the aerosol to the cells. The outcome was the CULTEX ® RFS (Mohr et al., 2010). In this study, we describe the differences between the two systems with regard to particle distribution and deposition clarifying the advantages and disadvantages of a radial to a linear aerosol distribution concept. Copyright © 2017 Elsevier GmbH. All rights reserved.

  9. Enviro-HIRLAM in Studies of Urban and Aerosol Impacts on Metropolitan Areas: Science-Education Approach

    Science.gov (United States)

    Mahura, Alexander; Nuterman, Roman; Mazeikis, Adomas; Gonzalez-Aparicio, Iratxe; Ivanov, Sergey; Palamarchuk, Julia

    2014-05-01

    To attract more perspective young scientists (and especially, MSc and PhD students) for advanced research and development of complex and modern modelling systems, a specific approach is required. It should allow within a short period of time to evaluate personal background levels, skills, capabilities, etc. To learn more about new potential science-oriented developers of the models, it is often not enough to look into the personal resume. Thus, a special event such as Young Scientist Summer School (YSSS) can be organized, where young researchers could have an opportunity to attend not only relevant lectures, but also participate in practical exercises allowing to solidify lecture materials. Here, the practical exercises are presented as independent small-scale (having duration of up to a week) research projects or studies oriented on specific topics of YSSS. Developed approach was tested and realized during 2008 and 2011 YSSS events held and organized in Zelenogorsk, Russia (by NetFAM et al.; http://netfam.fmi.fi/YSSS08) and Odessa, Ukraine (by MUSCATEN et al.; http://atmos.physic.ut.ee/~muscaten/YSSS/1info.html), respectively. It has been refined for the new YSSS (Jul 2014) to be organized by the COST Action EuMetChem. The main focus of all these YSSSs was/is on the integrated modelling of meteorological and chemical transport processes and impact of chemical weather on numerical weather prediction and climate modelling. During previous YSSSs some of such projects - "URBAN: The Influence of Metropolitan Areas on Meteorology", "AEROSOL: The Impact of Aerosols Effects on Meteorology", and "COASTAL: The Coastal & Cities Effects on Meteorology" - were focused on evaluation of influence of metropolitan areas on formation of meteorological and chemical fields above urban areas (such as Paris, France; Copenhagen, Denmark, and Bilbao, Spain) and surroundings. The Environment - HIgh Resolution Limited Area Model (Enviro-HIRLAM) was used and modifications were made taking

  10. Biomass burning aerosol transport and vertical distribution over the South African-Atlantic region: Aerosol Transport Over SE Atlantic

    Energy Technology Data Exchange (ETDEWEB)

    Das, Sampa [Department of Earth, Atmospheric and Planetary Sciences, Purdue University, West Lafayette Indiana USA; Harshvardhan, H. [Department of Earth, Atmospheric and Planetary Sciences, Purdue University, West Lafayette Indiana USA; Bian, Huisheng [Joint Center for Earth Systems Technology, UMBC, Baltimore Maryland USA; NASA Goddard Space Flight Center, Greenbelt Maryland USA; Chin, Mian [NASA Goddard Space Flight Center, Greenbelt Maryland USA; Curci, Gabriele [Department of Physical and Chemical Sciences, University of L' Aquila, L' Aquila Italy; Center of Excellence in Telesensing of Environment and Model Prediction of Severe events, University of L' Aquila, L' Aquila Italy; Protonotariou, Anna P. [Department of Physics, University of Athens, Athens Greece; Mielonen, Tero [Finnish Meteorological Institute, Kuopio Finland; Zhang, Kai [Pacific Northwest National Laboratory, Richland Washington USA; Wang, Hailong [Pacific Northwest National Laboratory, Richland Washington USA; Liu, Xiaohong [Department of Atmospheric Science, University of Wyoming, Laramie Wyoming USA

    2017-06-21

    Aerosols from wild-land fires could significantly perturb the global radiation balance and induce the climate change. In this study, the Community Atmospheric Model version 5 (CAM5) with prescribed daily fire aerosol emissions is used to investigate the spatial and seasonal characteristics of radiative forcings of wildfire aerosols including black carbon (BC) and particulate organic matter (POM). The global annual mean direct radiative forcing (DRF) of all fire aerosols is 0.15 W m-2, mainly due to the absorption of fire BC (0.25 W m-2), while fire POM induces a weak negative forcing (-0.05 W m-2). Strong positive DRF is found in the Arctic and in the oceanic regions west of South Africa and South America as a result of amplified absorption of fire BC above low-level clouds, in general agreement with satellite observations. The global annual mean cloud radiative forcing due to all fire aerosols is -0.70 W m-2, resulting mainly from the fire POM indirect forcing (-0.59 W m-2). The large cloud liquid water path over land areas of the Arctic favors the strong fire aerosol indirect forcing (up to -15 W m-2) during the Arctic summer. Significant surface cooling, precipitation reduction and low-level cloud amount increase are also found in the Arctic summer as a result of the fire aerosol indirect effect. The global annual mean surface albedo forcing over land areas (0.03 W m-2) is mainly due to the fire BC-on-snow forcing (0.02 W m-2) with the maximum albedo forcing occurring in spring (0.12 W m-2) when snow starts to melt.

  11. Pulmonary deposition of urban atmospheric aerosol. Assessments of the mass, number and surface of the deposited particles; Deposizione polmonare dell'aerosol atmosferico urbano in termini di massa, numero e superficie delle particelle

    Energy Technology Data Exchange (ETDEWEB)

    Luciani, A.; Berico, M.; Castellani, C.M. [ENEA, Centro Ricerche Ezio Clementel, Bologna (Italy). Dipt. Ambiente

    1998-07-01

    Pulmonary deposition of urban atmospheric aerosol has been calculated by means of the data derived from March 1995 measurement campaign of urban aerosol. The human respiratory tract model of the International Commission on Radiological Protection (n. 66) developed for radiation protection purposes has been used. The number and surface of the deposited particles, as well as the mass, have been also evaluated. [Italian] I dati relativi alla campagna di misure effettuata nel marzo 1995 sono stati rielaborati al fine di valutare la deposizione polmonare dell'aerosol atmosferico in area urbana. Le valutazioni di deposizione nel tratto respiratorio umano sono state condotte mediante l'utilizzo del modello del tratto respiratorio umano presentato per fini radioprotezionistici dalla International Commission on Radiological Protection (n. 66). Sono state effettuate valutazioni di deposizione in massa e in termini di numero e superficie delle particelle.

  12. Submicron aerosol distributions and CCN activity measured in and around the Korean Peninsula during KORUS-AQ

    Science.gov (United States)

    Park, M.; Kim, N.; Yum, S. S.; Thornhill, K. L., II; Anderson, B. E.; Kim, D. S.; Kim, H. J.; Jeon, H. E.; Park, Y. S.; Lee, S. B.

    2017-12-01

    KORUS-AQ is a field campaign aimed at investigating formation of ozone and aerosol and interactions between chemistry, transport and various sources in the Korean Peninsula which is the region affected both by long-range transport and local emission. Aerosol number concentration and size distribution, and CCN number concentration were measured on board the NASA DC-8 research aircraft and at a ground site at Olympic Park in Seoul, capital city of Korea during the KORUS-AQ campaign (May 2nd to June 10th, 2017). There were 20 flights during the KORUS-AQ campaign and total flight time was about 150 hours. CCN counter (CCNC) on the airborne platform was operated at the fixed internal supersaturation of 0.6% and CCNC at the ground site was operated at five different supersaturations (0.2%, 0.4%, 0.6%, 0.8%, and 1.0%). Aerosol hygroscopic parameter κ was also estimated from CCN number concentration and aerosol size distribution. Airborne measurements showed a large spatio-temporal variation of aerosol number concentration and CCN activity in and around the Korean peninsula, and the ground measurements also showed a large temporal variation. The campaign period can be classified into long-range transport dominant cases, local emission dominant cases due to stagnant air mass, and others. Aerosol number concentration in the Korean Peninsula measured in stagnant air mass period was higher than those in long-range transport period, but CCN number concentration showed an opposite tendency. Both aerosol and CCN number concentrations over the Yellow Sea in local emission period were slightly higher than those in long-range transport period. Since CCN activity is different depending on time and space, our focus is on understanding how CCN activity and aerosol hygroscopicity vary with the source of aerosol. Comprehensive analysis results will be shown at the conference.

  13. AOD distributions and trends of major aerosol species over a selection of the world’s most populated cities based on the 1st Version of NASA’s MERRA Aerosol Reanalysis

    Science.gov (United States)

    Provençal, Simon; Kishcha, Pavel; da Silva, Arlindo M.; Elhacham, Emily; Alpert, Pinhas

    2018-01-01

    NASA recently extended the Modern-Era Retrospective Analysis for Research and Application (MERRA) with an atmospheric aerosol reanalysis which includes five particulate species: sulfate, organic matter, black carbon, mineral dust and sea salt. The MERRA Aerosol Reanalysis (MERRAero) is an innovative tool to study air quality issues around the world for its global and constant coverage and its distinction of aerosol speciation expressed in the form of aerosol optical depth (AOD). The purpose of this manuscript is to apply MERRAero to the study of urban air pollution at the global scale by analyzing the AOD over a period of 13 years (2003–2015) and over a selection of 200 of the world’s most populated cities in order to assess the impacts of urbanization, industrialization, air quality regulations and regional transport which affect urban aerosol load. Environmental regulations and the recent global economic recession have helped to decrease the AOD and sulfate aerosols in most cities in North America, Europe and Japan. Rapid industrialization in China over the last two decades resulted in Chinese cities having the highest AOD values in the world. China has nevertheless recently implemented emission control measures which are showing early signs of success in many cities of Southern China where AOD has decreased substantially over the last 13 years. The AOD over South American cities, which is dominated by carbonaceous aerosols, has also decreased over the last decade due to an increase in commodity prices which slowed deforestation activities in the Amazon rainforest. At the opposite, recent urbanization and industrialization in India and Bangladesh resulted in a strong increase of AOD, sulfate and carbonaceous aerosols in most cities of these two countries. The AOD over most cities in Northern Africa and Western Asia changed little over the last decade. Emissions of natural aerosols, which cities in these two regions tend to be mostly composed of, don’t tend

  14. Seasonal monitoring and estimation of regional aerosol distribution over Po valley, northern Italy, using a high-resolution MAIAC product

    Science.gov (United States)

    Arvani, Barbara; Pierce, R. Bradley; Lyapustin, Alexei I.; Wang, Yujie; Ghermandi, Grazia; Teggi, Sergio

    2016-09-01

    In this work, the new 1 km-resolved Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm is employed to characterize seasonal PM10 - AOD correlations over northern Italy. The accuracy of the new dataset is assessed compared to the widely used Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 5.1 Aerosol Optical Depth (AOD) data, retrieved at 0.55 μm with spatial resolution of 10 km (MYD04_L2). We focused on evaluating the ability of these two products to characterize both temporal and spatial distributions of aerosols within urban and suburban areas. Ground PM10 measurements were obtained from 73 of the Italian Regional Agency for Environmental Protection (ARPA) monitoring stations, spread across northern Italy, during a three-year period from 2010 to 2012. The Po Valley area (northern Italy) was chosen as the study domain because of its severe urban air pollution, resulting from it having the highest population and industrial manufacturing density in the country, being located in a valley where two surrounding mountain chains favor the stagnation of pollutants. We found that the global correlations between the bin-averaged PM10 and AOD are R2 = 0.83 and R2 = 0.44 for MYD04_L2 and for MAIAC, respectively, suggesting a greater sensitivity of the high-resolution product to small-scale deviations. However, the introduction of Relative Humidity (RH) and Planetary Boundary Layer (PBL) depth corrections allowed for a significant improvement to the bin-averaged PM - AOD correlation, which led to a similar performance: R2 = 0.96 for MODIS and R2 = 0.95 for MAIAC. Furthermore, the introduction of the PBL information in the corrected AOD values was found to be crucial in order to capture the clear seasonal cycle shown by measured PM10 values. The study allowed us to define four seasonal linear correlations that estimate PM10 concentrations satisfactorily from the remotely sensed MAIAC AOD retrieval. Overall, the results show that the high

  15. Improved source apportionment of organic aerosols in complex urban air pollution using the multilinear engine (ME-2)

    Science.gov (United States)

    Zhu, Qiao; Huang, Xiao-Feng; Cao, Li-Ming; Wei, Lin-Tong; Zhang, Bin; He, Ling-Yan; Elser, Miriam; Canonaco, Francesco; Slowik, Jay G.; Bozzetti, Carlo; El-Haddad, Imad; Prévôt, André S. H.

    2018-02-01

    Organic aerosols (OAs), which consist of thousands of complex compounds emitted from various sources, constitute one of the major components of fine particulate matter. The traditional positive matrix factorization (PMF) method often apportions aerosol mass spectrometer (AMS) organic datasets into less meaningful or mixed factors, especially in complex urban cases. In this study, an improved source apportionment method using a bilinear model of the multilinear engine (ME-2) was applied to OAs collected during the heavily polluted season from two Chinese megacities located in the north and south with an Aerodyne high-resolution aerosol mass spectrometer (HR-ToF-AMS). We applied a rather novel procedure for utilization of prior information and selecting optimal solutions, which does not necessarily depend on other studies. Ultimately, six reasonable factors were clearly resolved and quantified for both sites by constraining one or more factors: hydrocarbon-like OA (HOA), cooking-related OA (COA), biomass burning OA (BBOA), coal combustion (CCOA), less-oxidized oxygenated OA (LO-OOA) and more-oxidized oxygenated OA (MO-OOA). In comparison, the traditional PMF method could not effectively resolve the appropriate factors, e.g., BBOA and CCOA, in the solutions. Moreover, coal combustion and traffic emissions were determined to be primarily responsible for the concentrations of PAHs and BC, respectively, through the regression analyses of the ME-2 results.

  16. Visibility degradation and light scattering/absorption due to aerosol particles in urban/suburban atmosphere of Irbid, Jordan

    International Nuclear Information System (INIS)

    Hamasha, K. M.; University of Tabuk, Tabuk

    2010-01-01

    Visible light scattering and absorption patterns were measured using a photoacoustic instrument at different locations in Irbid city. Measurments were perfoemed during the intervals 1-9 August 2007 and 7-13 October 2007 at the city center site (Palestine street) and the southern site (University Circle), respectively. The city center site is impacted by local urban and regional aerosols. The southern site is dominated by regional aerosols. Data from both sampling sites showed variety of diurnal light absorption and scattering patterns. During most of the measurement days, the highest light absorption peaks appeared in the morning, 7:00 - 9:30 AM, whereas the highest light scattering peaks appeared later, 9:30 - 11:00 AM. The earlier light absorption peaks are likely attributed to the elevated black carbon vehicular emission during the heavy traffic hours (rush hours) whereas, the later light scattering peaks are attributed to secondary aerosols generted in the atmosphere through photochmical reactions. The southern site (University Circle) exhibited a higher light scattering and a lower light absorption contribution to the light extinction, leading to a better visibility compared to the City Center site. The visibility is averaged at 44 km and 115 km at the city center site and southern site, respectively. (author).

  17. Chemical Composition Based Aerosol Optical Properties According to Size Distribution and Mixture Types during Smog and Asian Dust Events in Seoul, Korea

    Science.gov (United States)

    Jung, Chang Hoon; Lee, Ji Yi; Um, Junshik; Lee, Seung Soo; Kim, Yong Pyo

    2018-02-01

    This study investigated the optical properties of aerosols involved in different meteorological events, including smog and Asian dust days. Carbonaceous components and inorganic species were measured in Seoul, Korea between 25 and 31 March 2012. Based on the measurements, the optical properties of aerosols were calculated by considering composition, size distribution, and mixing state of aerosols. To represent polydisperse size distributions of aerosols, a lognormal size distribution with a wide range of geometric mean diameters and geometric standard deviations was used. For the optical property calculations, the Mie theory was used to compute single-scattering properties of aerosol particles with varying size and composition. Analysis of the sampled data showed that the water-soluble components of organic matter increased on smog days, whereas crustal elements increased on dust days. The water content significantly influenced the optical properties of aerosols during the smog days as a result of high relative humidity and an increase in the water-soluble component. The absorption coefficients depended on the aerosol mixture type and the aerosol size distributions. Therefore, to improve our knowledge on radiative impacts of aerosols, especially the regional impacts of aerosols in East Asia, accurate measurements of aerosols, such as size distribution, composition, and mixture type, under different meteorological conditions are required.

  18. Corporative Trends in Urban Distribution of Goods in Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Antun, J.P.

    2016-07-01

    The Logistics processes in urban-metropolitan distribution are constantly changing, both technological support and technical implementation in the processes themselves and in the management of these. It is necessary to monitor the substantive changes outlined in the metropolitan urban-physical distribution of goods, because they contribute to a better competitive position of companies in the market, and also to a better development of city life. It is a professional scientific and technical task that contributes, by its impact on {sup b}enchmarking{sup ,} the improvement of engineering practices in the professional community of executives in logistics and supply chains. Based on three extensive field research (ANTÚN, JP; LOZANO, A; HERNÁNDEZ, R; ALARCÓN, R et al 2007; ANTÚN, JP; LOZANO, A; MAGALLANES, R; ALARCÓN, R; GRANADOS, F 2009, ANTUN JP ALARCON R; 2014) on Logistics Distribution of Goods in Mexico City, this article presents and discusses major corporate trends on a set of key logistics processes, and bring examples from Case Studies. (Author)

  19. Optical properties of the urban aerosol and their relation to chemical composition

    International Nuclear Information System (INIS)

    Leaderer, B.P.; Stolwijk, J.A.J.

    1980-01-01

    Light extinction and resulting visibility degradation in an unsaturated precipitation-free atmosphere are determined by light absorption and scattering and are caused by a complex mix of natural components and anthropogenic pollutants. The paper reviews correlation studies relating light scattering and light extinction (visibility) to concentrations of sulfate mass, nitrate mass, the remainder of the mass, and in some cases organic aerosol mass, while accounting for variations in relative humidity. It is found that sulfate aerosol mass is the dominant chemical aerosol species affecting light scattering and extinction. The dominant effect of sulfate mass on light scattering and extinction, even when sulfates account for a relatively small fraction of the total mass, results from the fact that sulfates are secondary aerosols and are mostly found in the 0.1-1.0 micron size range

  20. Aliphatic and polycyclic aromatic hydrocarbons characterisation of Coimbra and Oporto PM2.5 urban aerosol

    Science.gov (United States)

    Rocha, A. C.; Mirante, F.; Gonçalves, C.; Nunes, T.; Alves, C.; Evtyugina, M.; Kowacz, M.; Pio, C.; Rocha, C.; Vasconcelos, T.

    2009-04-01

    The concentration of organic pollutants in urban areas is mostly due to incomplete combustion from vehicles, industries and domestic heating. Some of these compounds, principally the aliphatic (ALIPH) and polycyclic aromatic hydrocarbons (PAHs) promote harmful effects in human health. The determination of the ALIPH and PAHs concentration levels and their possible emission sources are useful for air quality management and source apportionment studies. In order to estimate and compare the ambient concentrations and establish the main sources of these compounds, the fine fraction of the atmospheric particulate matter (PM2.5) was collected simultaneously in Oporto and Coimbra during summer and winter seasons using a high volume sampler. The organic compounds were extracted from the particulate matter, under reflux with dichloromethane and the total organic extract (TOE) was fractionated by flash chromatography using five different eluents with increasing polarity. The hydrocarbon fractions were analysed by gas chromatography/mass spectrometry (GC/MS). Here we present and discuss the qualitative and quantitative composition of the aliphatic and aromatic fractions present in PM2.5 samples from both cities. The homologous series of C14 to C34 n-alkanes, isoprenoid hydrocarbons (pristane and phytane), PAHs and some petroleum markers have been identified and quantified. With the purpose of identifying the possible sources, various molecular diagnostic ratios were calculated. The global carbon preference index (CPI) closer to the unity, the large concentration of the unresolved complex mixture (UCM) and the presence of PAHs indicate that motor vehicle exhaust was the main emission source of the aliphatic and polycyclic aromatic fractions of Oporto and Coimbra aerosol, especially in the first city. Also, the remarkable presence of petroleum biomarkers such, as hopanes, confirms the previous results. Concentration ratios between PAHs were calculated and used to assign emission

  1. [Size distributions and source apportionment of soluble ions in aerosol in Nanjing].

    Science.gov (United States)

    Xue, Guo-Qiang; Zhu, Bin; Wang, Hong-Lei

    2014-05-01

    To explore the seasonal variation and source apportionment of soluble ions in PM10, PM2.1 and PM1.1, the aerosol mass. concentration and soluble ion concentration were investigated during a one-year observation in the urban-district and north suburb. As the results showed, (1)The concentrations of PM10, PM2.1, PM1.1 were in the order of winter > spring > autumn > summer. In spring, summer and autumn, the concentrations of PM10, PM2.1, PM1.1 in the north suburb were higher than in the urban, while the situation, was opposite in winter. (2) SO(2-)(4), NO(-)(3), Ca2+, NH(+)(4), Cl-, K+, Na+, F-, NO;, Mg2+ were measured, and their total concentration in PM10 was 46 microg.m -3 in urban sites and 39.6 microg m in north suburbs. Mass fraction percentage o f water soluble ion in PM2.1-10, PM1 1-2.1, PM1.1 in the urban district increased from 20.4% to 49.5% and 56% , and the value in the north suburb increased from 18.3% to 37. 9% and 42.5%. (3) Major ions, SO(2-)(4), NO(-)(3) , NH(+)(4) , second components and Ca2+ , had significant seasonal variation. In the urban district, the highest concentrations were observed in winter, and the lowest in summer, while in the. north suburb, the highest concentrations were observed in spring, and the lowest in summer. The seasonal changing climate in Nanjing and different anthropogenic influences with land surface in urban-suburb may be the major factors for the ions' seasonal variation. (4) NH(+)(4) , SO(2-)(4) , NO(-)(3) came from secondary chemical reactions of NH3, SO2, NO,, and these precursors mostly came from automobile exhaust in Summer while equally came from automobile exhaust and fossil fuel in winter. Cl- came from biomass burning in Winter . while transported from sea salt with Na+ in Summer. Ca2+ and Mg2+ came from ground dust and construction dust. K+, F- , NO(-)(2) may come from biomass burning and industrial emissions.

  2. Simulating Aerosol Size Distribution and Mass Concentration with Simultaneous Nucleation, Condensation/Coagulation, and Deposition with the GRAPES-CUACE

    Science.gov (United States)

    Zhou, Chunhong; Shen, Xiaojing; Liu, Zirui; Zhang, Yangmei; Xin, Jinyuan

    2018-04-01

    A coupled aerosol-cloud model is essential for investigating the formation of haze and fog and the interaction of aerosols with clouds and precipitation. One of the key tasks of such a model is to produce correct mass and number size distributions of aerosols. In this paper, a parameterization scheme for aerosol size distribution in initial emission, which took into account the measured mass and number size distributions of aerosols, was developed in the GRAPES-CUACE [Global/Regional Assimilation and PrEdiction System-China Meteorological Administration (CMA) Unified Atmospheric Chemistry Environment model]—an online chemical weather forecast system that contains microphysical processes and emission, transport, and chemical conversion of sectional multi-component aerosols. In addition, the competitive mechanism between nucleation and condensation for secondary aerosol formation was improved, and the dry deposition was also modified to be in consistent with the real depositing length. Based on the above improvements, the GRAPES-CUACE simulations were verified against observational data during 1-31 January 2013, when a series of heavy regional haze-fog events occurred in eastern China. The results show that the aerosol number size distribution from the improved experiment was much closer to the observation, whereas in the old experiment the number concentration was higher in the nucleation mode and lower in the accumulation mode. Meanwhile, the errors in aerosol number size distribution as diagnosed by its sectional mass size distribution were also reduced. Moreover, simulations of organic carbon, sulfate, and other aerosol components were improved and the overestimation as well as underestimation of PM2.5 concentration in eastern China was significantly reduced, leading to increased correlation coefficient between simulated and observed PM2.5 by more than 70%. In the remote areas where bad simulation results were produced previously, the correlation coefficient

  3. Season-dependent size distribution of aerosols over the tropical coastal environment of south-west India

    Science.gov (United States)

    Aryasree, S.; Nair, Prabha R.

    2018-01-01

    This paper presents the results of a detailed study on the size characteristics of aerosols at the tropical coastal site Thiruvananthapuram based on the in-situ measurements of size resolved aerosol number density using an aerosol spectrometer, covering a period of 28 months from September 2011 to December 2013. The diurnal pattern of aerosol number density is characterized by day time low and a two-fold increase during nighttime and these changes are closely associated with the strong mesoscale features namely the sea breeze and land breeze prevailing at the site. Aerosol Number Size Distribution (NSD) depicts a multi-modal nature with two prominent modes, one ≤0.1 μm and other ∼1 μm. Two other less pronounced modes are also observed in the NSD, one ∼0.3-0.5 μm and other ∼5-8 μm. The NSDs also exhibited strong seasonal changes linked with the synoptic meteorological feature of this region namely the South Asian monsoon. The seasonal NSDs were parameterized and analyzed. In addition to this, the effects of meteorological parameters temperature, relative humidity, and wind speed and airflow patterns on aerosol number density as revealed by partial correlation analysis were found to be aerosol size dependent.

  4. Spatial and temporal variability of carbonaceous aerosols: Assessing the impact of biomass burning in the urban environment.

    Science.gov (United States)

    Titos, G; Del Águila, A; Cazorla, A; Lyamani, H; Casquero-Vera, J A; Colombi, C; Cuccia, E; Gianelle, V; Močnik, G; Alastuey, A; Olmo, F J; Alados-Arboledas, L

    2017-02-01

    Biomass burning (BB) is a significant source of atmospheric particles in many parts of the world. Whereas many studies have demonstrated the importance of BB emissions in central and northern Europe, especially in rural areas, its impact in urban air quality of southern European countries has been sparsely investigated. In this study, highly time resolved multi-wavelength absorption coefficients together with levoglucosan (BB tracer) mass concentrations were combined to apportion carbonaceous aerosol sources. The Aethalometer model takes advantage of the different spectral behavior of BB and fossil fuel (FF) combustion aerosols. The model was found to be more sensitive to the assumed value of the aerosol Ångström exponent (AAE) for FF (AAE ff ) than to the AAE for BB (AAE bb ). As result of various sensitivity tests the model was optimized with AAE ff =1.1 and AAE bb =2. The Aethalometer model and levoglucosan tracer estimates were in good agreement. The Aethalometer model was further applied to data from three sites in Granada urban area to evaluate the spatial variation of CM ff and CM bb (carbonaceous matter from FF or BB origin, respectively) concentrations within the city. The results showed that CM bb was lower in the city centre while it has an unexpected profound impact on the CM levels measured in the suburbs (about 40%). Analysis of BB tracers with respect to wind speed suggested that BB was dominated by sources outside the city, to the west in a rural area. Distinguishing whether it corresponds to agricultural waste burning or with biomass burning for domestic heating was not possible. This study also shows that although traffic restrictions measures contribute to reduce carbonaceous concentrations, the extent of the reduction is very local. Other sources such as BB, which can contribute to CM as much as traffic emissions, should be targeted to reduce air pollution. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. High-time resolved measurements of biogenic and anthropogenic secondary organic aerosol precursors and products in urban air

    Science.gov (United States)

    Flores, Rosa M.; Doskey, Paul V.

    2016-04-01

    Volatile organic compounds (VOCs), which are present in the atmosphere entirely in the gas phase are directly emitted by biogenic (~1089 Tg yr-1) and anthropogenic sources (~185 Tg yr-1). However, the sources and molecular speciation of intermediate VOCs (IVOCs), which are for the most part also present almost entirely in the gas phase, are not well characterized. The VOCs and IVOCs participate in reactions that form ozone and semivolatile OC (SVOC) that partition into the aerosol phase. Formation and evolution of secondary organic aerosol (SOA) are part of a complex dynamic process that depends on the molecular speciation and concentration of VOCs, IVOCs, primary organic aerosol (POA), and the level of oxidants (NO3, OH, O3). The current lack of understanding of OA properties and their impact on radiative forcing, ecosystems, and human health is partly due to limitations of models to predict SOA production on local, regional, and global scales. More accurate forecasting of SOA production requires high-temporal resolution measurement and molecular characterization of SOA precursors and products. For the subject study, the IVOCs and aerosol-phase organic matter were collected using the high-volume sampling technique and were analyzed by multidimensional gas chromatography with time-of-flight mass spectrometry (GCxGC-ToFMS). The IVOCs included terpenes, terpenoids, n-alkanes, branched alkanes, isoprenoids, alkylbenzenes, cycloalkylbenzenes, PAH, alkyl PAH, and an unresolved complex mixture (UCM). Diurnal variations of OA species containing multiple oxygenated functionalities and selected SOA tracers of isorprene, α-pinene, toluene, cyclohexene, and n-dodecane oxidation were also quantified. The data for SOA precursor and oxidation products presented here will be useful for evaluating the ability of molecular-specific SOA models to forecast SOA production in and downwind of urban areas.

  6. Sensitivity of cloud albedo to aerosol concentration and spectral dispersion of cloud droplet size distribution

    Energy Technology Data Exchange (ETDEWEB)

    Iorga, G. [Faculty of Chemistry, University of Bucharest, Bucharest (Romania)]. E-mail: giorga@gw-chimie.math.unibuc.ro; Stefan, S. [Faculty of Physics, University of Bucharest, Bucharest (Romania)

    2007-07-15

    Both the enhancement of the aerosol number concentration and the relative dispersion of the cloud droplet size distribution (spectral dispersion) on a regional scale can modify the cloud reflectivity. This work is focused on the role that pre-cloud aerosol plays in cloud reflectivity. Log-normal aerosol size distributions were used to describe two aerosol types: marine and rural. The number of aerosols that activate to droplets was obtained based on Abdul-Razzak and Ghan's (2000) activation parameterization. The cloud albedo taking into account the spectral dispersion effect in the parameterization of cloud effective radius and in the scattering asymmetry factor has been estimated. Two different scaling factors to account for dispersion were used. The sensitivity of cloud albedo to spectral dispersion-cloud droplet number concentration relationship in connection to the changes in liquid water content (LWC), and the cloud droplet effective radius has been also investigated. We obtained higher values of effective radius when dispersion is taken into account, with respect to the base case (without considering dispersion). The inferred absolute differences in effective radius values between calculations with each of the scaling factors are below 0.8 {mu}m as LWC ranges between 0.1 and 1.0 g m-3. The optical depth decreased by up to 14% (marine), and up to 29% (continental) when dispersion is considered in both effective radius and asymmetry factor ({beta}LDR scaling factor). Correspondingly, the relative change in cloud albedo is up to 6% (marine) and up to 11% (continental) clouds. For continental clouds, the calculated effective radius when dispersion is considered fits well within the measured range of effective radius in SCAR-B project. The calculated cloud albedo when dispersion is considered shows better agreement with the estimated cloud albedo from measured effective radius in SCAR-B project than the cloud albedo calculated without dispersion. In cleaner

  7. Column-integrated aerosol optical properties and direct radiative forcing over the urban-industrial megacity Nanjing in the Yangtze River Delta, China.

    Science.gov (United States)

    Kang, Na; Kumar, K Raghavendra; Yu, Xingna; Yin, Yan

    2016-09-01

    Aerosol optical properties were measured and analyzed through the ground-based remote sensing Aerosol Robotic Network (AERONET) over an urban-industrial site, Nanjing (32.21° N, 118.72° E, and 62 m above sea level), in the Yangtze River Delta, China, during September 2007-August 2008. The annual averaged values of aerosol optical depth (AOD500) and the Ångström exponent (AE440-870) were measured to be 0.94 ± 0.52 and 1.10 ± 0.21, respectively. The seasonal averaged values of AOD500 (AE440-870) were noticed to be high in summer (autumn) and low in autumn (spring). The characterization of aerosol types showed the dominance of mixed type followed by the biomass burning and urban-industrial type of aerosol at Nanjing. Subsequently, the curvature (a 2) obtained from the second-order polynomial fit and the second derivative of AE (α') were also analyzed to understand the dominant aerosol type. The single scattering albedo at 440 nm (SSA440) varied from 0.88 to 0.93 with relatively lower (higher) values during the summer (spring), suggesting an increase in black carbon and mineral dust (desert dust) aerosols of absorbing (scattering) nature. The averaged monthly and seasonal evolutions of shortwave (0.3-4.0 μm) direct aerosol radiative forcing (DARF) values were computed from the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model both at the top of atmosphere (TOA) and bottom of atmosphere (SUR) during the study period. Further, the aerosol forcing efficiency (AFE) and the corresponding atmospheric heating rates (AHR) were also estimated from the forcing within the atmosphere (ATM). The derived DARF values, therefore, produced a warming effect within the atmosphere due to strong absorption of solar radiation.

  8. Urban distribution centers : a means to reducing freight vehicle miles traveled.

    Science.gov (United States)

    2011-02-01

    The present study examines the model of freight consolidation platforms, and urban distribution centers (UDCs) in particular, as a means to solve the last mile problem of urban freight while reducing vehicle miles traveled and associated environmenta...

  9. Seasonal and spatial variation of organic tracers for biomass burning in PM1 aerosols from highly insolated urban areas.

    Science.gov (United States)

    van Drooge, B L; Fontal, M; Bravo, N; Fernández, P; Fernández, M A; Muñoz-Arnanz, J; Jiménez, B; Grimalt, J O

    2014-10-01

    PM1 aerosol characterization on organic tracers for biomass burning (levoglucosan and its isomers and dehydroabietic acid) was conducted within the AERTRANS project. PM1 filters (N = 90) were sampled from 2010 to 2012 in busy streets in the urban centre of Madrid and Barcelona (Spain) at ground-level and at roof sites. In both urban areas, biomass burning was not expected to be an important local emission source, but regional emissions from wildfires, residential heating or biomass removal may influence the air quality in the cities. Although both areas are under influence of high solar radiation, Madrid is situated in the centre of the Iberian Peninsula, while Barcelona is located at the Mediterranean Coast and under influence of marine atmospheres. Two extraction methods were applied, i.e. Soxhlet and ASE, which showed equivalent results after GC-MS analyses. The ambient air concentrations of the organic tracers for biomass burning increased by an order of magnitude at both sites during winter compared to summer. An exception was observed during a PM event in summer 2012, when the atmosphere in Barcelona was directly affected by regional wildfire smoke and levels were four times higher as those observed in winter. Overall, there was little variation between the street and roof sites in both cities, suggesting that regional biomass burning sources influence the urban areas after atmospheric transport. Despite the different atmospheric characteristics in terms of air relative humidity, Madrid and Barcelona exhibit very similar composition and concentrations of biomass burning organic tracers. Nevertheless, levoglucosan and its isomers seem to be more suitable for source apportionment purposes than dehydroabietic acid. In both urban areas, biomass burning contributions to PM were generally low (2 %) in summer, except on the day when wildfire smoke arrive to the urban area. In the colder periods the contribution increase to around 30 %, indicating that regional

  10. Role of the Atmospheric General Circulation on the Temporal Variability of the Aerosol Distribution over Dakar (Senegal)

    Science.gov (United States)

    Senghor, Habib; Machu, Eric; Hourdin, Frederic; Thierno Gaye, Amadou; Gueye, Moussa; Simina Drame, Mamadou

    2016-04-01

    The natural or anthropogenic aerosols play an important role on the climate system and the human health through their optical and physical properties. To evaluate the potential impacts of these aerosols, it is necessary to better understand their temporal variability in relation with the atmospheric ciculation. Some previous case studies have pointed out the influence of the sea-breeze circulation on the vertical distribution of the aerosols along the Western African coast. In the present work, Lidar (Ceilometer CL31; located at Dakar) data are used for the period 2012-2014 together with Level-3 data from CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) between 2007 and 2014 for studying the seasonal cycle of the vertical distribution of aerosols over Dakar (17.5°W, 14.74°N). Both instruments show strong seasonal variability with a maximum of aerosol occurrence in May over Dakar. The CL31 shows a crucial impact of sea-breeze circulation on the diurnal cycle of the Mixed Atmospheric Boundary Layer and a strong dust signal in spring in the nocturnal low-level jet (LLJ) located between 500 and 1000 m altitudes over Dakar.

  11. Seasonal variations of ultra-fine and submicron aerosols in Taipei, Taiwan: implications for particle formation processes in a subtropical urban area

    Directory of Open Access Journals (Sweden)

    H. C. Cheung

    2016-02-01

    Full Text Available The aim of this study is to investigate the seasonal variations in the physicochemical properties of atmospheric ultra-fine particles (UFPs, d ≤ 100 nm and submicron particles (PM1, d ≤ 1 µm in an east Asian urban area, which are hypothesized to be affected by the interchange of summer and winter monsoons. An observation experiment was conducted at TARO (Taipei Aerosol and Radiation Observatory, an urban aerosol station in Taipei, Taiwan, from October 2012 to August 2013. The measurements included the mass concentration and chemical composition of UFPs and PM1, as well as the particle number concentration (PNC and the particle number size distribution (PSD with size range of 4–736 nm. The results indicated that the mass concentration of PM1 was elevated during cold seasons with a peak level of 18.5 µg m−3 in spring, whereas the highest concentration of UFPs was measured in summertime with a mean of 1.64 µg m−3. Moreover, chemical analysis revealed that the UFPs and PM1 were characterized by distinct composition; UFPs were composed mostly of organics, whereas ammonium and sulfate were the major constituents of PM1. The seasonal median of total PNCs ranged from 13.9  ×  103 cm−3 in autumn to 19.4  ×  103 cm−3 in spring. Median concentrations for respective size distribution modes peaked in different seasons. The nucleation-mode PNC (N4 − 25 peaked at 11.6  ×  103 cm−3 in winter, whereas the Aitken-mode (N25 − 100 and accumulation-mode (N100 − 736 PNC exhibited summer maxima at 6.0  ×  103 and 3.1  ×  103 cm−3, respectively. The change in PSD during summertime was attributed to the enhancement in the photochemical production of condensable organic matter that, in turn, contributed to the growth of aerosol particles in the atmosphere. In addition, clear photochemical production of particles was observed, mostly in the summer season

  12. Towards Scalable Distributed Framework for Urban Congestion Traffic Patterns Warehousing

    Directory of Open Access Journals (Sweden)

    A. Boulmakoul

    2015-01-01

    Full Text Available We put forward architecture of a framework for integration of data from moving objects related to urban transportation network. Most of this research refers to the GPS outdoor geolocation technology and uses distributed cloud infrastructure with big data NoSQL database. A network of intelligent mobile sensors, distributed on urban network, produces congestion traffic patterns. Congestion predictions are based on extended simulation model. This model provides traffic indicators calculations, which fuse with the GPS data for allowing estimation of traffic states across the whole network. The discovery process of congestion patterns uses semantic trajectories metamodel given in our previous works. The challenge of the proposed solution is to store patterns of traffic, which aims to ensure the surveillance and intelligent real-time control network to reduce congestion and avoid its consequences. The fusion of real-time data from GPS-enabled smartphones integrated with those provided by existing traffic systems improves traffic congestion knowledge, as well as generating new information for a soft operational control and providing intelligent added value for transportation systems deployment.

  13. Rural and urban distribution of trauma incidents in Scotland.

    Science.gov (United States)

    Morrison, J J; McConnell, N J; Orman, J A; Egan, G; Jansen, J O

    2013-02-01

    Trauma systems reduce mortality and improve functional outcomes from injury. Regional trauma networks have been established in several European regions to address longstanding deficiencies in trauma care. A perception of the geography and population distribution as challenging has delayed the introduction of a trauma system in Scotland. The characteristics of trauma incidents attended by the Scottish Ambulance Service were analysed, to gain a better understanding of the geospatial characteristics of trauma in Scotland. Data on trauma incidents collected by the Scottish Ambulance Service between November 2008 and October 2010 were obtained. Incident location was analysed by health board region, rurality and social deprivation. The results are presented as number of patients, average annual incidence rates and relative risks. Of the 141,668 incidents identified, 72·1 per cent occurred in urban regions. The risk of being involved in an incident was similar across the most populous regions, and decreased slightly with increasing rurality. Social deprivation was associated with greater numbers and risk. A total of 53·1 per cent of patients were taken to a large general hospital, and 38·6 per cent to a teaching hospital; the distribution was similar for the subset of incidents involving patients with physiological derangements. The majority of trauma incidents in Scotland occur in urban and deprived areas. A regionalized system of trauma care appears plausible, although the precise configuration of such a system requires further study. Copyright © 2012 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.

  14. Mid-infrared mapping of Jupiter's temperatures, aerosol opacity and chemical distributions with IRTF/TEXES

    Science.gov (United States)

    Fletcher, Leigh N.; Greathouse, T. K.; Orton, G. S.; Sinclair, J. A.; Giles, R. S.; Irwin, P. G. J.; Encrenaz, T.

    2016-11-01

    disequilibrium material. Temperate mid-latitudes display a correlation between mid-IR aerosol opacity and the white albedo features in visible light (i.e., zones). We find hemispheric asymmetries in the distribution of tropospheric PH3, stratospheric hydrocarbons and the 2D wind field (estimated via the thermal-wind equation) that suggest a differing efficiency of mechanical forcing (e.g., vertical mixing and wave propagation) between the two hemispheres that we argue is driven by dynamics rather than Jupiter's small seasonal cycle. Jupiter's stratosphere is notably warmer at northern mid-latitudes than in the south in both 2000 and 2014, although the latter can be largely attributed to strong thermal wave activity near 30°N that dominates the 2014 stratospheric maps and may be responsible for elevated C2H2 in the northern hemisphere. A vertically-variable pattern of temperature and windshear minima and maxima associated with Jupiter's Quasi Quadrennial Oscillation (QQO) is observed at the equator in both datasets, although the contrasts were more subdued in 2014. Large-scale equator-to-pole gradients in ethane and acetylene are superimposed on top of the mid-latitude mechanically-driven maxima, with C2H2 decreasing from equator to pole and C2H6 showing a polar enhancement, consistent with a radiatively-controlled circulation from low to high latitudes. Cold polar vortices beyond ∼60° latitude can be identified in the upper tropospheric and lower stratospheric temperature maps, suggesting enhanced radiative cooling from polar aerosols. Finally, compositional mapping of the Great Red Spot confirms the local enhancements in PH3 and aerosols, the north-south asymmetry in NH3 gas and the presence of a warm southern periphery that have been noted by previous authors.

  15. Relative importance of nitrate and sulfate aerosol production mechanisms in urban atmospheres

    International Nuclear Information System (INIS)

    Middleton, P.; Kiang, C.S.

    1979-01-01

    The relative importance of the various sulfate and nitrate aerosol production mechanisms is calculated for different atmospheric conditions. The calculation scheme used to determine the rates of nitrate and sulfate production, based on the concept that vapor transfer to the aerosols and nitrate and sulfate formation within the aerosols are coupled kinetic processes, considers sulfate formation by ozone and hydrogen peroxide oxidation and catalytic oxidation in the presence of soot, iron and manganese of sulfite solutions and sulfuric acid condensation and nitrate formation by the liquid-phase oxidation of dissolved nitrogen oxides for different initial gas concentrations and particle compositions and sizes. It is found that sulfate production is higher under daytime conditions, primarily proceeding by mechanisms involving sulfuric acid and hydrogen peroxide, while at night oxidation processes on the surface of the aerosol film are more important. Nitrate tends to decrease nighttime sulfate production due to an increase in aerosol acidity and nitrate production is found to be higher under nighttime conditions and in the winter

  16. An investigation of processes controlling the evolution of the boundary layer aerosol size distribution properties at the Swedish background station Aspvreten

    Directory of Open Access Journals (Sweden)

    P. Tunved

    2004-01-01

    Full Text Available Aerosol size distributions have been measured at the Swedish background station Aspvreten (58.8° N, 17.4° E. Different states of the aerosol were determined using a novel application of cluster analysis. The analysis resulted in eight different clusters capturing different stages of the aerosol lifecycle. The atmospheric aerosol size distributions were interpreted as belonging to fresh, intermediate and aged types of size distribution. With aid of back trajectory analysis we present statistics concerning the relation of source area and different meteorological parameters using a non-Lagrangian approach. Source area is argued to be important although not sufficient to describe the observed aerosol properties. Especially processing by clouds and precipitation is shown to be crucial for the evolution of the aerosol size distribution. As much as 60% of the observed size distributions present features that are likely to be related to cloud processes or wet deposition. The lifetime properties of different sized aerosols are discussed by means of measured variability of the aerosol size distribution. Processing by clouds and precipitation is shown to be especially crucial in the size range 100 nm and larger. This indicates an approximate limit for activation in clouds to 100 nm in this type of environment. The aerosol lifecycle is discussed. Size distributions indicating signs of recent new particle formation (~30% of the observed size distributions represent the first stage in the lifecycle. Aging of the aerosol size distribution may follow two branches: either growth by condensation and coagulation or processing by non-precipitating clouds. In both cases mass is accumulated. Wet removal is the main process capable of removing aerosol mass. Wet deposition is argued to be an important mechanism in reaching a state where nucleation may occur (i.e. sufficiently low aerosol surface area in environments similar to the one studied.

  17. Aerosol indirect effects on lightning in the generation of induced NOx and tropospheric ozone over an Indian urban metropolis

    Science.gov (United States)

    Saha, Upal; Maitra, Animesh; Talukdar, Shamitaksha; Jana, Soumyajyoti

    Lightning flashes, associated with vigorous convective activity, is one of the most prominent weather phenomena in the tropical atmosphere. High aerosol loading is indirectly associated with the increase in lightning flash rates via the formation of tropospheric ozone during the pre-monsoon and monsoon over the tropics. Tropospheric ozone, an important greenhouse pollutant gas have impact on Earth’s radiation budget and play a key role in changing the atmospheric circulation patterns. Lightning-induced NOx is a primary pollutant found in photochemical smog and an important precursor for the formation of tropospheric ozone. A critical analysis is done to study the indirect effects of high aerosol loading on the formation of tropospheric ozone via lightning flashes and induced NOx formation over an urban metropolitan location Kolkata (22°32'N, 88°20'E), India during the period 2001-2012. The seasonal variation of lightning flash rates (LFR), taken from TRMM-LIS 2.5o x 2.5o gridded dataset, show that the LFR was observed to be intensified in the pre-monsoon (March-May) and high in monsoon (June-September) months over the region. Aerosol Optical Depth (AOD) at 555nm, taken from MISR 0.5o x 0.5o gridded level-3 dataset, plays an indirect effect on the increase in LFR during the pre-monsoon and monsoon months and has positive correlations between them during these periods. This is also justified from the seasonal variation of the increase in LFR due to the increase in AOD over the region during 2001-2012. The calibrated GOME and OMI/AURA satellite data analysis shows that the tropospheric ozone, formed as a result of lightning-induced NOx and due to the increased AOD at 555 nm, also increases during the pre-monsoon and monsoon months. The seasonal variation of lightning-induced tropospheric NOx, taken from SCIAMACHY observations also justified the fact that the pre-monsoon and monsoon LFR solely responsible for the generation of induced NOx over the region. The

  18. Spatial distribution of aerosol black carbon over India during pre-monsoon season

    Science.gov (United States)

    Beegum, S. Naseema; Moorthy, K. Krishna; Babu, S. Suresh; Satheesh, S. K.; Vinoj, V.; Badarinath, K. V. S.; Safai, P. D.; Devara, P. C. S.; Singh, Sacchidanand; Vinod; Dumka, U. C.; Pant, P.

    Aerosol black carbon (BC) mass concentrations ([BC]), measured continuously during a mutli-platform field experiment, Integrated Campaign for Aerosols gases and Radiation Budget (ICARB, March-May 2006), from a network of eight observatories spread over geographically distinct environments of India, (which included five mainland stations, one highland station, and two island stations (one each in Arabian Sea and Bay of Bengal)) are examined for their spatio-temporal characteristics. During the period of study, [BC] showed large variations across the country, with values ranging from 27 μg m -3 over industrial/urban locations to as low as 0.065 μg m -3 over the Arabian Sea. For all mainland stations, [BC] remained high compared to highland as well as island stations. Among the island stations, Port Blair (PBR) had higher concentration of BC, compared to Minicoy (MCY), implying more absorbing nature of Bay of Bengal aerosols than Arabian Sea. The highland station Nainital (NTL), in the central Himalayas, showed low values of [BC], comparable or even lower than that of the island station PBR, indicating the prevalence of cleaner environment over there. An examination of the changes in the mean temporal features, as the season advances from winter (December-February) to pre-monsoon (March-May), revealed that: (a) Diurnal variations were pronounced over all the mainland stations, with an afternoon low and a nighttime high; (b) At the islands, the diurnal variations, though resembled those over the mainlands, were less pronounced; and (c) In contrast to this, highland station showed an opposite pattern with an afternoon high and a late night or early morning low. The diurnal variations at all stations are mainly caused by the dynamics of local Atmospheric Boundary Layer (ABL). At the entire mainland as well as island stations (except HYD and DEL), [BC] showed a decreasing trend from January to May. This is attributed to the increased convective mixing and to the

  19. Statistical analysis and parameterization of the hygroscopic growth of the sub-micrometer urban background aerosol in Beijing

    Science.gov (United States)

    Wang, Yu; Wu, Zhijun; Ma, Nan; Wu, Yusheng; Zeng, Limin; Zhao, Chunsheng; Wiedensohler, Alfred

    2018-02-01

    The take-up of water of aerosol particles plays an important role in heavy haze formation over North China Plain, since it is related with particle mass concentration, visibility degradation, and particle chemistry. In the present study, we investigated the size-resolved hygroscopic growth factor (HGF) of sub-micrometer aerosol particles (smaller than 350 nm) on a basis of 9-month Hygroscopicity-Tandem Differential Mobility Analyzer measurement in the urban background atmosphere of Beijing. The mean hygroscopicity parameter (κ) values derived from averaging over the entire sampling period for particles of 50 nm, 75 nm, 100 nm, 150 nm, 250 nm, and 350 nm in diameters were 0.14 ± 0.07, 0.17 ± 0.05, 0.18 ± 0.06, 0.20 ± 0.07, 0.21 ± 0.09, and 0.23 ± 0.12, respectively, indicating the dominance of organics in the sub-micrometer urban aerosols. In the spring, summer, and autumn, the number fraction of hydrophilic particles increased with increasing particle size, resulting in an increasing trend of overall particle hygroscopicity with enhanced particle size. Differently, the overall mean κ values peaked in the range of 75-150 nm and decreased for particles larger than 150 nm in diameter during wintertime. Such size-dependency of κ in winter was related to the strong primary particle emissions from coal combustion during domestic heating period. The number fraction of hydrophobic particles such as freshly emitted soot decreased with increasing PM2.5 mass concentration, indicating aged and internal mixed particles were dominant in the severe particulate matter pollution. Parameterization schemes of the HGF as a function of relative humidity (RH) and particle size between 50 and 350 nm were determined for different seasons and pollution levels. The HGFs calculated from the parameterizations agree well with the measured HGFs at 20-90% RH. The parameterizations can be applied to determine the hygroscopic growth of aerosol particles at ambient conditions for the area

  20. The fluorescence properties of aerosol larger than 0.8 μm in urban and tropical rainforest locations

    Science.gov (United States)

    Gabey, A. M.; Stanley, W. R.; Gallagher, M. W.; Kaye, P. H.

    2011-06-01

    UV-LIF measurements were performed on ambient aerosol in Manchester, UK (urban city centre, winter) and Borneo, Malaysia (remote, tropical) using a Wide Issue Bioaerosol Spectrometer, version 3 (WIBS3). These sites are taken to represent environments with minor and significant primary biological aerosol (PBA) influences respectively, and the urban dataset describes the fluorescent background aerosol against which PBA must be identified by researchers using LIF. The ensemble aerosol at both sites was characterised over 2-3 weeks by measuring the fluorescence intensity and optical equivalent diameter (DP) of single particles sized 0.8 ≤ DP ≤ 20 μm. Filter samples were also collected for a subset of the Manchester campaign and analysed using energy dispersive X-Ray (EDX) spectroscopy and environmental scanning electron microscopy (ESEM), which revealed mostly non-PBA at D ≤ 1 μm. The WIBS3 features three fluorescence channels: the emission following a 280 nm excitation is recorded at 310-400 nm (channel F1) and 400-600 nm (F2), and fluorescence excited at 350 nm is detected at 400-600 nm (F3). In Manchester the primary size mode of fluorescent and non-fluorescent material was present at 0.8-1.2 μm, with a secondary fluorescent mode at 2-4 μm. In Borneo non-fluorescent material peaked at 0.8-1.2 μm and fluorescent at 3-4 μm. Agreement between fluorescent number concentrations in each channel differed at the two sites, with F1 and F3 reporting similar concentrations in Borneo but F3 outnumbering F1 by a factor of 2-3 across the size spectrum in Manchester. The fluorescence intensity in each channel generally rose with DP at both sites with the exception of F1 intensity in Manchester, which peaked at DP = 4 μm, causing a divergence between F1 and F3 intensity at larger DP. This divergence and the differing fluorescent particle concentrations demonstrate the additional discrimination provided by the F1 channel in Manchester. The relationships between

  1. Factors influencing the outdoor concentration of carbonaceous aerosols at urban schools in Brisbane, Australia: Implications for children's exposure

    International Nuclear Information System (INIS)

    Crilley, L.R.; Ayoko, G.A.; Mazaheri, M.; Morawska, L.

    2016-01-01

    This comprehensive study aimed to determine the sources and driving factors of organic carbon (OC) and elemental carbon (EC) concentrations in ambient PM 2.5 in urban schools. Sampling was conducted outdoors at 25 schools in the Brisbane Metropolitan Area, Australia. Concentrations of primary and secondary OC were quantified using the EC tracer method, with secondary OC accounting for an average of 60%. Principal component analysis distinguished the contributing sources above the background and identified groups of schools with differing levels of primary and secondary carbonaceous aerosols. Overall, the results showed that vehicle emissions, local weather conditions and secondary organic aerosols (SOA) were the key factors influencing concentrations of carbonaceous component of PM 2.5 at these schools. These results provide insights into children's exposure to vehicle emissions and SOA at such urban schools. - Highlights: • We aimed to find the contributing sources to children's exposure at school. • Measured outdoor organic carbon and elemental carbon at 25 urban schools. • Schools varied in exposure to primary and secondary sources. • Secondary organic carbon the largest component of carbonaceous aerosols. • Vehicle emission levels at schools are primarily dependent on local traffic counts. - Key factors influencing concentrations of carbonaceous component of PM 2.5 at urban schools were found to be vehicle emissions, secondary organic aerosols and local weather conditions.

  2. [Airborne Fungal Aerosol Concentration and Distribution Characteristics in Air- Conditioned Wards].

    Science.gov (United States)

    Zhang, Hua-ling; Feng, He-hua; Fang, Zi-liang; Wang, Ben-dong; Li, Dan

    2015-04-01

    The effects of airborne fungus on human health in the hospital environment are related to not only their genera and concentrations, but also their particle sizes and distribution characteristics. Moreover, the mechanisms of aerosols with different particle sizes on human health are different. Fungal samples were obtained in medicine wards of Chongqing using a six-stage sampler. The airborne fungal concentrations, genera and size distributions of all the sampling wards were investigated and identified in detail. Results showed that airborne fungal concentrations were not correlated to the diseases or personnel density, but were related to seasons, temperature, and relative humidity. The size distribution rule had roughly the same for testing wards in winter and summer. The size distributions were not related with diseases and seasons, the percentage of airborne fungal concentrations increased gradually from stage I to stage III, and then decreased dramatically from stage V to stage VI, in general, the size of airborne fungi was a normal distribution. There was no markedly difference for median diameter of airborne fungi which was less 3.19 μm in these wards. There were similar dominant genera in all wards. They were Aspergillus spp, Penicillium spp and Alternaria spp. Therefore, attention should be paid to improve the filtration efficiency of particle size of 1.1-4.7 μm for air conditioning system of wards. It also should be targeted to choose appropriate antibacterial methods and equipment for daily hygiene and air conditioning system operation management.

  3. Aerosols, clouds, and precipitation in the North Atlantic trades observed during the Barbados aerosol cloud experiment – Part 1: Distributions and variability

    Directory of Open Access Journals (Sweden)

    E. Jung

    2016-07-01

    Full Text Available Shallow marine cumulus clouds are by far the most frequently observed cloud type over the Earth's oceans; but they are poorly understood and have not been investigated as extensively as stratocumulus clouds. This study describes and discusses the properties and variations of aerosol, cloud, and precipitation associated with shallow marine cumulus clouds observed in the North Atlantic trades during a field campaign (Barbados Aerosol Cloud Experiment- BACEX, March–April 2010, which took place off Barbados where African dust periodically affects the region. The principal observing platform was the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS Twin Otter (TO research aircraft, which was equipped with standard meteorological instruments, a zenith pointing cloud radar and probes that measured aerosol, cloud, and precipitation characteristics.The temporal variation and vertical distribution of aerosols observed from the 15 flights, which included the most intense African dust event during all of 2010 in Barbados, showed a wide range of aerosol conditions. During dusty periods, aerosol concentrations increased substantially in the size range between 0.5 and 10 µm (diameter, particles that are large enough to be effective giant cloud condensation nuclei (CCN. The 10-day back trajectories showed three distinct air masses with distinct vertical structures associated with air masses originating in the Atlantic (typical maritime air mass with relatively low aerosol concentrations in the marine boundary layer, Africa (Saharan air layer, and mid-latitudes (continental pollution plumes. Despite the large differences in the total mass loading and the origin of the aerosols, the overall shapes of the aerosol particle size distributions were consistent, with the exception of the transition period.The TO was able to sample many clouds at various phases of growth. Maximum cloud depth observed was less than ∼ 3 km, while most

  4. Impacts of urbanization on nitrogen cycling and aerosol, surface and groundwater transport in semi-arid regions

    Science.gov (United States)

    Lohse, K. A.; Gallo, E.; Carlson, M.; Riha, K. M.; Brooks, P. D.; McIntosh, J. C.; Sorooshian, A.; Michalski, G. M.; Meixner, T.

    2011-12-01

    Semi-arid regions are experiencing disproportionate increases in human population and land transformation worldwide, taxing limited water resources and altering nitrogen (N) biogeochemistry. How the redistribution of water and N by urbanization affects semi-arid ecosystems and downstream water quality (e.g. drinking water) is unclear. Understanding these interactions and their feedbacks will be critical for developing science-based management strategies to sustain these limited resources. This is especially true in the US where some of the fastest growing urban areas are in semi-arid ecosystems, where N and water cycles are accelerated, and intimately coupled, and where runoff from urban ecosystems is actively managed to augment a limited water supply to the growing human population. Here we synthesize several ongoing studies from the Tucson Basin in Arizona and examine how increasing urban land cover is altering rainfall-runoff relationships, groundwater recharge, water quality, and long range transport of atmospheric N. Studies across 5 catchments varying in impervious land cover showed that only the least impervious catchment responded to antecedent moisture conditions while hydrologic responses were not statistically related to antecedent rainfall conditions at more impervious sites. Regression models indicated that rainfall depth, imperviousness, and their combined effect control discharge and runoff ratios (p channel characteristics and infrastructure controlled runoff chemistry. Groundwater studies showed nonpoint source contamination of CFCs and associated nitrate in areas of rapid recharge along ephemeral channels. Aerosol measurements indicate that both long-range transport of N and N emissions from Tucson are being transported and deposited at high elevation in areas that recharge regional groundwater. Combined, our findings suggest that urbanization in semi-arid regions results in tradeoffs in the redistribution of water and N that have important

  5. Characterizing the Vertical Distribution of Aerosols using Ground-based Multiwavelength Lidar Data

    Science.gov (United States)

    Ferrare, R. A.; Thorsen, T. J.; Clayton, M.; Mueller, D.; Chemyakin, E.; Burton, S. P.; Goldsmith, J.; Holz, R.; Kuehn, R.; Eloranta, E. W.; Marais, W.; Newsom, R. K.; Liu, X.; Sawamura, P.; Holben, B. N.; Hostetler, C. A.

    2016-12-01

    Observations of aerosol optical and microphysical properties are critical for developing and evaluating aerosol transport model parameterizations and assessing global aerosol-radiation impacts on climate. During the Combined HSRL And Raman lidar Measurement Study (CHARMS), we investigated the synergistic use of ground-based Raman lidar and High Spectral Resolution Lidar (HSRL) measurements to retrieve aerosol properties aloft. Continuous (24/7) operation of these co-located lidars during the ten-week CHARMS mission (mid-July through September 2015) allowed the acquisition of a unique, multiwavelength ground-based lidar dataset for studying aerosol properties above the Southern Great Plains (SGP) site. The ARM Raman lidar measured profiles of aerosol backscatter, extinction and depolarization at 355 nm as well as profiles of water vapor mixing ratio and temperature. The University of Wisconsin HSRL simultaneously measured profiles of aerosol backscatter, extinction and depolarization at 532 nm and aerosol backscatter at 1064 nm. Recent advances in both lidar retrieval theory and algorithm development demonstrate that vertically-resolved retrievals using such multiwavelength lidar measurements of aerosol backscatter and extinction can help constrain both the aerosol optical (e.g. complex refractive index, scattering, etc.) and microphysical properties (e.g. effective radius, concentrations) as well as provide qualitative aerosol classification. Based on this work, the NASA Langley Research Center (LaRC) HSRL group developed automated algorithms for classifying and retrieving aerosol optical and microphysical properties, demonstrated these retrievals using data from the unique NASA/LaRC airborne multiwavelength HSRL-2 system, and validated the results using coincident airborne in situ data. We apply these algorithms to the CHARMS multiwavelength (Raman+HSRL) lidar dataset to retrieve aerosol properties above the SGP site. We present some profiles of aerosol effective

  6. Determination of the bioaccessible fraction of metals in urban aerosol using simulated lung fluids

    Czech Academy of Sciences Publication Activity Database

    Coufalík, Pavel; Mikuška, Pavel; Matoušek, Tomáš; Večeřa, Zbyněk

    2016-01-01

    Roč. 140, SEP (2016), s. 469-475 ISSN 1352-2310 R&D Projects: GA ČR(CZ) GA14-25558S; GA ČR(CZ) GA13-01438S Institutional support: RVO:68081715 Keywords : metal * aerosol * simulated lung fluid Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.629, year: 2016

  7. Sub-micron particle number size distribution characteristics at two urban locations in Leicester

    Science.gov (United States)

    Hama, Sarkawt M. L.; Cordell, Rebecca L.; Kos, Gerard P. A.; Weijers, E. P.; Monks, Paul S.

    2017-09-01

    The particle number size distribution (PNSD) of atmospheric particles not only provides information about sources and atmospheric processing of particles, but also plays an important role in determining regional lung dose. Owing to the importance of PNSD in understanding particulate pollution two short-term campaigns (March-June 2014) measurements of sub-micron PNSD were conducted at two urban background locations in Leicester, UK. At the first site, Leicester Automatic Urban Rural Network (AURN), the mean number concentrations of nucleation, Aitken, accumulation modes, the total particles, equivalent black carbon (eBC) mass concentrations were 2002, 3258, 1576, 6837 # cm-3, 1.7 μg m-3, respectively, and at the second site, Brookfield (BF), were 1455, 2407, 874, 4737 # cm-3, 0.77 μg m-3, respectively. The total particle number was dominated by the nucleation and Aitken modes, with both consisting of 77%, and 81% of total number concentrations at AURN and BF sites, respectively. This behaviour could be attributed to primary emissions (traffic) of ultrafine particles and the temporal evolution of mixing layer. The size distribution at the AURN site shows bimodal distribution at 22 nm with a minor peak at 70 nm. The size distribution at BF site, however, exhibits unimodal distribution at 35 nm. This study has for the first time investigated the effect of Easter holiday on PNSD in UK. The temporal variation of PNSD demonstrated a good degree of correlation with traffic-related pollutants (NOX, and eBC at both sites). The meteorological conditions, also had an impact on the PNSD and eBC at both sites. During the measurement period, the frequency of NPF events was calculated to be 13.3%, and 22.2% at AURN and BF sites, respectively. The average value of formation and growth rates of nucleation mode particles were 1.3, and 1.17 cm-3 s-1 and 7.42, and 5.3 nm h-1 at AURN, and BF sites, respectively. It can suggested that aerosol particles in Leicester originate mainly

  8. Aerosol ionic components at Mt. Heng in central southern China: abundances, size distribution, and impacts of long-range transport.

    Science.gov (United States)

    Gao, Xiaomei; Xue, Likun; Wang, Xinfeng; Wang, Tao; Yuan, Chao; Gao, Rui; Zhou, Yang; Nie, Wei; Zhang, Qingzhu; Wang, Wenxing

    2012-09-01

    Water-soluble ions in PM(2.5) were continuously measured, along with the measurements of many other species and collection of size-resolved aerosol samples, at the summit of Mt. Heng in the spring of 2009, to understand the sources of aerosols in rural central southern China. The mean concentrations of SO(4)(2-), NH(4)(+) and NO(3)(-) in PM(2.5) were 8.02, 2.94 and 1.47 μg/m(3), indicating a moderate aerosol pollution level at Mt. Heng. Water-soluble ions composed approximately 40% of the PM(2.5) mass on average. PM(2.5) was weakly acidic with about 66% of the samples being acidic. SO(4)(2-), NO(3)(-) and NH(4)(+) exhibited similar diurnal patterns with a broad afternoon maximum. SO(4)(2-) and NH(4)(+) were mainly present in the fine aerosols with a peak in the droplet mode of 0.56-1 μm, suggesting the important role of cloud processing in the formation of aerosol sulfate. NO(3)(-) was largely distributed in the coarse particles with a predominant peak in the size-bin of 3.2-5.6 μm. Long-distance transport of processed air masses, dust aerosols, and cloud/fog processes were the major factors determining the variations of fine aerosol at Mt. Heng. The results at Mt. Heng were compared with those obtained from our previous study at Mt. Tai in north China. The comparison revealed large differences in the aerosol characteristics and processes between southern and northern China. Backward trajectories indicated extensive transport of anthropogenic pollution from the coastal regions of eastern/northern China and the Pearl River Delta (PRD) to Mt. Heng in spring, highlighting the need for regionally coordinated control measures for the secondary pollutants. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Variations of aerosol size distribution, chemical composition and optical properties from roadside to ambient environment: A case study in Hong Kong, China

    Science.gov (United States)

    Zhang, Qian; Ning, Zhi; Shen, Zhenxing; Li, Guoliang; Zhang, Junke; Lei, Yali; Xu, Hongmei; Sun, Jian; Zhang, Leiming; Westerdahl, Dane; Gali, Nirmal Kumar; Gong, Xuesong

    2017-10-01

    This study investigated the ;roadside-to-ambient; evolution of particle physicochemical and optical properties in typical urban atmospheres of Hong Kong through collection of chemically-resolved PM2.5 data and PM2.5 size distribution at a roadside and an ambient site. Roadside particle size distribution showed typical peaks in the nuclei mode (30-40 nm) while ambient measurements peaked in the Aitken mode (50-70 nm), revealing possible condensation and coagulation growth of freshly emitted particles during aging processes. Much higher levels of anthropogenic chemical components, i.e. nitrate, sulfate, ammonium, organic carbon (OC) and elemental carbon (EC), but lower levels of OC/EC and secondary inorganic aerosols (SIA)/EC ratios appeared in roadside than ambient particles. The high OC/EC and SIA/EC ratios in ambient particles implied high contributions from secondary aerosols. Black carbon (BC), a strong light absorbing material, showed large variations in optical properties when mixed with other inorganic and organic components. Particle-bound polycyclic aromatic hydrocarbons (p-PAHs), an indicator of brown carbon (BrC), showed significant UV-absorbing ability. The average BC and p-PAHs concentrations were 3.8 and 87.6 ng m-3, respectively, at the roadside, but were only 1.5 and 18.1 ng m-3 at the ambient site, suggesting BC and p-PAHs concentrations heavily driven by traffic emissions. In contrast, PM2.5 UV light absorption coefficients (babs-BrC,370nm) at the ambient site (4.2 Mm-1) and at the roadside site (4.1 Mm-1) were similar, emphasizing that particle aging processes enhanced UV light-absorbing properties, a conclusion that was also supported by the finding that the Absorption Ångström coefficient (AAC) value at UV wavelengths (AAC_UV band) at the ambient site were ∼1.7 times higher than that at the roadside. Both aqueous reaction and photochemically produced secondary organic aerosol (SOA) for ambient aerosols contributed to the peak values of babs

  10. Evaluation of aerosol distributions in the GISS-TOMAS global aerosol microphysics model with remote sensing observations

    Directory of Open Access Journals (Sweden)

    Y. H. Lee

    2010-03-01

    Full Text Available The Aerosol Optical Depth (AOD and Angstrom Coefficient (AC predictions in the GISS-TOMAS model of global aerosol microphysics are evaluated against remote sensing data from MODIS, MISR, and AERONET. The model AOD agrees well (within a factor of two over polluted continental (or high sulfate, dusty, and moderate sea-salt regions but less well over the equatorial, high sea-salt, and biomass burning regions. Underprediction of sea-salt in the equatorial region is likely due to GCM meteorology (low wind speeds and high precipitation. For the Southern Ocean, overprediction of AOD is very likely due to high sea-salt emissions and perhaps aerosol water uptake in the model. However, uncertainties in cloud screening at high latitudes make it difficult to evaluate the model AOD there with the satellite-based AOD. AOD in biomass burning regions is underpredicted, a tendency found in other global models but more severely here. Using measurements from the LBA-SMOCC 2002 campaign, the surface-level OC concentration in the model are found to be underpredicted severely during the dry season while much less severely for EC concentration, suggesting the low AOD in the model is due to underpredictions in OM mass. The potential for errors in emissions and wet deposition to contribute to this bias is discussed.

  11. Quantifying dust plume formation and aerosol size distribution during the Saharan Mineral Dust Experiment in North Africa

    KAUST Repository

    Khan, Basit Ali

    2015-01-01

    Dust particles mixed in the free troposphere have longer lifetimes than airborne particles near the surface. Their cumulative radiative impact on earth’s meteorological processes and climate might be significant despite their relatively small contribution to total dust abundance. One example is the elevated dust--laden Saharan Air Layer (SAL) over the equatorial North Atlantic, which cools the sea surface and likely suppresses hurricane activity. To understand the formation mechanisms of SAL, we combine model simulations and dust observations collected during the first stage of the Saharan Mineral Dust Experiment (SAMUM--I), which sampled dust events that extended from Morocco to Portugal, and investigated the spatial distribution and the microphysical, optical, chemical, and radiative properties of Saharan mineral dust. We employed the Weather Research Forecast model coupled with the Chemistry/Aerosol module (WRF--Chem) to reproduce the meteorological environment and spatial and size distributions of dust. The experimental domain covers northwest Africa including the southern Sahara, Morocco and part of the Atlantic Ocean with 5 km horizontal grid spacing and 51 vertical layers. The experiments were run from 20 May to 9 June 2006, covering the period of most intensive dust outbreaks. Comparisons of model results with available airborne and ground--based observations show that WRF--Chem reproduces observed meteorological fields as well as aerosol distribution across the entire region and along the airplane’s tracks. We evaluated several aerosol uplift processes and found that orographic lifting, aerosol transport through the land/sea interface with steep gradients of meteorological characteristics, and interaction of sea breezes with the continental outflow are key mechanisms that form a surface--detached aerosol plume over the ocean. Comparisons of simulated dust size distributions with airplane and ground--based observations are generally good, but suggest

  12. Carbonaceous and inorganic aerosols over a sub-urban site in peninsular India: Temporal variability and source characteristics

    Science.gov (United States)

    Aswini, A. R.; Hegde, Prashant; Nair, Prabha R.

    2018-01-01

    PM10 aerosol samples collected from a sub-urban site in Coimbatore during pre-monsoon, monsoon, post-monsoon and winter from 2014 to 2016 showed a large variability from 7.6 to 89 μg m- 3 with an annual average of 41 ± 21 μg m- 3 (N = 69). High abundance of PM10 and other components were recorded during winter and lowest during monsoon period. Total carbonaceous aerosols and water soluble ionic species contributed to 31% and 45% of PM10 mass respectively. SO42 - was the most abundant species (average 9.8 ± 4.8 μg m- 3) and constituted for 24% of total mass. Organic Carbon (OC) was the next most abundant species ranging from 1 to 16 μg m- 3 with an average of 7 ± 3.6 μg m- 3 accounting for 17% of PM10 mass concentration. POC (primary organic carbon) and SOC (secondary organic carbon) accounted for 56% and 44% of OC respectively. A major portion of OC ( 60%) was found to be water soluble. The correlation between OC and EC (elemental carbon) was found to be higher for night-time compared to daytime suggesting their origin from common sources during night-time. K+ was found to be strongly correlated with OC during night-time. WSOC showed good correlation with POC and K+ which was high especially during night-time. WSON (water soluble organic nitrogen) accounted for 34% of water soluble total nitrogen (WSTN). HCO3- exhibited significant positive correlation with Ca2 + during daytime indicating their crustal origin. The observations suggest that the region is influenced by biomass burning sources, however during day-time, secondary production and terrestrial sources (due to high temperature and wind) significantly influence the atmospheric aerosols over this region.

  13. Differences of diurnal variations of some aliphatic and polycyclic aromatic hydrocarbons concentrations in aerosols of the urban area of Madrid

    International Nuclear Information System (INIS)

    Perez, M. M.; Perez-Pastor, R. M.; Bea, F. J.; Campos, A.; Gonzalez, D.

    1991-01-01

    A study on daily concentration changes of polycyclic aromatic and aliphatic hydrocarbons (PAH's and AH's), was carried out in aerosols sampled m the Ciudad Universitaria of Madrid. Samples were taken at morning and night during February and June, for short sampling times, on glass fiber filters in Hi-Vol samplers, and then extracted ultrasonically with cyclohexane. Analysis were performed by HRGC with fused-silica capillary columns. The variable traffic rate, and the strong influence during winter periods of domestic heating are characteristic of this place. The aim of this work was to evaluate diurnal and seasonal variations of selected AH and PAH in the urban area of Madrid, by using descriptive parameters, such as total concentrations of AH and PAH, characteristic profiles and predominance carbon index. (Author)

  14. Differences of diurnal variations of some aliphatic and polycyclic aromatic hydrocarbons concentrations in aerosol of the urban area of Madrid

    International Nuclear Information System (INIS)

    Perez Garcia, M.M.; Perez Pastor, R.M.; Bea, J.F.; Campos, A.; Gonzalez Diaz, D.

    1990-01-01

    A study on daily concentration changes of polycyclic aromatic and aliphatic hydrocarbons (PAH's and AH's), was carried out in aerosols sampled in the Ciudad Universitaria of Madrid. Samples were taken at morning and night during February and June, for short sampling times, on glass fiber filters in Hi-Vol samplers, and then extracted ultrasonically with cyclohexane. Analysis were performed by HRGC with fused-silica capillary columns. The variable traffic rate, and the strong influence during winter periods of domestic heating are characteristic of this place. The aim of this work was to evaluate diurnal and seasonal variations of selected AH and PAH in the urban area of Madrid, by using descriptive parameters, such as total concentrations of AH and PAH, characteristic profiles and predominance carbon index. From these results, it has been tried to identify emission sources of the studied hydrocarbons. (Author). 10 refs

  15. Submicrometer aerosol in rural and urban backgrounds in southern Poland: primary and secondary components of PM1.

    Science.gov (United States)

    Rogula-Kozłowska, Wioletta; Klejnowski, Krzysztof

    2013-01-01

    Diurnal samples of PM(1) (submicrometer particles, having aerodynamic diameters not greater than 1 μm) were collected at an urban background site in Zabrze (from 01.08. to 31.12.2009) and a rural background site in Racibórz (from 01.08. to 31.12.2010). The samples were analyzed for carbon (organic and elemental), water soluble ions (Na(+), NH(4) (+), K(+), Mg(2+), Ca(2+), Cl(-), NO(3)(-), SO(4)(2-)) and concentrations of 21 elements by using, respectively, a Sunset Laboratory carbon analyzer, a Herisau Metrohm AG ion chromatograph, a PANalitycal Epsilon 5 spectrometer. To perform the monthly mass closure calculations for PM(1), the chemical components were categorized into organic matter (OM), elemental carbon (EC), secondary inorganic aerosol (SIA), crustal matter (CM), marine components (MC), other elements (OE) and unidentified matter (UM). The mass contributions of secondary (SOM) and primary (POM) organic matter to PM(1) were also estimated. In average, 50 % of PM(1) in Zabrze and 40 % in Racibórz were secondary aerosol coming from the transformations of its gaseous precursors. High concentrations and mass contributions of EC and OM to PM, and probable PM acidic nature in Zabrze, indicate particularly high hazard from the ambient submicrometer particles to the inhabitants of southern Poland.

  16. Distribution of trace gases and aerosols in the Siberian air shed during wildfires of summer 2012

    Science.gov (United States)

    Belan, Boris D.; Paris, Jean-Daiel; Nedelec, Philippe; Antokhin, Pavel N.; Arshinova, Victoriya; Arshinov, Mikhail Yu.; Belan, Sergey B.; Davydov, Denis K.; Ivlev, Georgii A.; Fofonov, Alexandre V.; Kozlov, Artem V.; Rasskazchikova, Tatyana M.; Savkin, Denis E.; Simonenkov, Denis V.; Sklyadneva, Tatyana K.; Tolmachev, Gennadii N.

    2017-04-01

    During the last two decades, three strong biomass burning events have been observed in Russia: two of them in 2002 and 2010 in the European part of Russia, and another one in 2012 in West and East Siberia. In this paper we present results of the extensive airborne study of the vertical distribution of trace gases and aerosols carried out during strong wildfire event happened in summer 2012 in Siberia. For this purpose, the Optik TU-134 aircraft laboratory was used as a research platform. A large-scale airborne campaign has been undertaken along the route Novosibirsk-Mirny-Yakutsk-Bratsk-Novosibirsk on 31st of July and 1st of August, 2012. Flight pattern consisted of a number of ascents and descents between close to the ground and 8 km altitude that enabled 20 vertical profiles to be obtained. Campaign was conducted under the weather conditions of low-gradient baric field that determined the low speed transport of air masses, as well as the accumulation of biomass burning emissions in the region under study. Highest concentrations of CO2, CH4 and CO over wildfire spots reached 432 ppm, 2367 ppb, and 4036 ppb, correspondingly. If we exclude from the analysis the data obtained when crossing smoke plumes, we can find a difference between background concentrations measured in the atmosphere over regions affected by biomass burning and clean areas. Enhancement of CO2 over the wildfire areas changed with altitude. On average, it was 10.5 ppm in the atmospheric boundary layer (ABL) and 5-6 ppm in the free troposphere. Maximum CO2 enhancements reached 27 ppm and 24 ppm, correspondingly. The averaged CH4 enhancement varied from 75 ppb in the boundary layer to 30 ppb in the upper troposphere, and a little bit lower than 30 ppb in the middle troposphere. Maximum CH4 enhancements reached 202 ppb, 108 ppb, and 50-60 ppb, correspondingly. The averaged and maximum enhancements of CO differed by an order of magnitude. Thus, in the ABL the maximum difference in concentration between

  17. Variations in atmospheric PM trace metal content in Spanish towns: Illustrating the chemical complexity of the inorganic urban aerosol cocktail

    Science.gov (United States)

    Moreno, Teresa; Querol, Xavier; Alastuey, Andrés; Viana, Mar; Salvador, Pedro; Sánchez de la Campa, Ana; Artiñano, Begoña; de la Rosa, Jesús; Gibbons, Wes

    The majority of the Spanish urban population breathe air containing inhalable ambient airborne particles at average concentrations of 30-46 μg m -3 (PM 10) and 20-30 μg m -3 (PM 2.5). Even though the average weight of inhaled urban aerosol is commonly similar, however, there can be large chemical differences between the ambient dusts from different towns, including the more bioreactive elements such as some metals. In this context, we compare the source-apportioned trace metal content of airborne PM 10 and PM 2.5 collected daily over a 1-year period from six population centres in Spain: Barcelona, Alcobendas, Llodio, Huelva, Tarragona and Las Palmas de Gran Canaria. Total average trace metal (ΣTM) PM 10 and PM 2.5 contents vary by up to a factor of around 3, reaching a maximum of ΣTM 10 811 ng m -3 and ΣTM 2.5 503 ng m -3 at Llodio, an industrial but humid site with the lowest PM 10 mass levels but high contamination by Zn, Pb, Mn, Sn, Ni and Cr. In contrast, pollution at Huelva, although another industrially influenced site, instead emphasises Cu and As, whereas Barcelona, where traffic emissions and resuspension contribute to some of the highest average PM 10 levels in Spain, has unusually raised levels of Ti, V and Ba. Such variations in both daily and annual average PM bulk chemistry, particularly in potentially toxic trace metals concentrated in the finer aerosols (such as Cd, As, Pb, Hg and Ni), predict that PM health effects on resident populations from different towns are unlikely to be the same.

  18. Single-particle characterization of urban aerosol particles collected in three Korean cites using low-Z electron probe X-ray microanalysis.

    Science.gov (United States)

    Ro, Chul-Un; Kim, HyeKyeong; Oh, Keun-Young; Yea, Sun Kyung; Lee, Chong Bum; Jang, Meongdo; Van Grieken, René

    2002-11-15

    A recently developed single-particle analytical technique, called low-Z electron probe X-ray microanalysis (low-Z EPMA), was applied to characterize urban aerosol particles collected in three cities of Korea (Seoul, CheongJu, and ChunCheon) on single days in the winter of 1999. In this study, it is clearly demonstrated that the low-Z EPMA technique can provide detailed and quantitative information on the chemical composition of particles in the urban atmosphere. The collected aerosol particles were analyzed and classified on the basis of their chemical species. Various types of particles were identified, such as soil-derived, carbonaceous, marine-originated, and anthropogenic particles. In the sample collected in Seoul, carbonaceous, aluminosilicates, silicon dioxide, and calcium carbonate aerosol particles were abundantly encountered. In the CheongJu and ChunCheon samples, carbonaceous, aluminosilicates, reacted sea salts, and ammonium sulfate aerosol particles were often seen. However, in the CheongJu sample, ammonium sulfate particles were the most abundant in the fine fraction. Also, calcium sulfate and nitrate particles were significantly observed. In the ChunCheon sample, organic particles were the most abundant in the fine fraction. Also, sodium nitrate particles were seen at high levels. The ChunCheon sample seemed to be strongly influenced by sea-salt aerosols originating from the Yellow Sea, which is located about 115 km away from the city.

  19. Aerosol vertical distribution, new particle formation, and jet aircraft particle emissions in the free troposhere and tropopause region; Vertikalverteilung und Neubildungsprozesse des Aerosols und partikelfoermige Flugzeugemissionen in der freien Troposphaere und Tropopausenregion

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, F P

    2000-07-01

    A contribution to the understanding of natural and anthropogenously induced particle formation as well as aerosol physical transformation processes within the free troposphere (FT) is introduced. Documentation and interpretation of empirical data relevant with respect to possible climatologic impact of anthropogenous aerosol emissions into the atmosphere is presented. The first section describes new technique for high spatial resolution measurements of ultrafine aerosol particles by condensation nucleus counters (CNCs), a necessary prerequisite for the observation of natural particle formation and jet aircraft emissions. The second section illustrates vertical distribution and variability ranges of the aerosol in the FT and the tropopause region (TP). Typical microphysical states of the atmospheric aerosol within the Northern Hemisphere are documented by means of systematic measurements during more than 60 flight missions. Simple mathematical parameterizations of the aerosol vertical distribution and aerosol size distributions are developed. Important aerosol sources within the FT are localized and possible aerosol formation processes are discussed. The third section is focussed on jet-engine particle emissions within the FT and TP. A unique inflight experiment for detection of extremely high concentrations (>10{sup 6} cm{sup -3}) of extremely small (donw to <3 nm) aerosols inside the exhaust plumes of several jet aircraft is described. Particle emission indices and emission-controlling parameters are deduced. Most important topic is the impact of fuel sulfur content of kerosine on number, size and chemical composition of jet particle emissions. Generalized results are parameterized in form of lognormal aerosol particle size distributions. (orig.) [German] Ein Beitrag zum Verstaendnis natuerlicher und anthropogen induzierter Aerosolneubildung sowie physikalischer Aerosolumwandlung in der freien Troposphaere wird vorgestellt. Empirisch gewonnenes Datenmaterial wird

  20. Aerosol optical characteristics and their vertical distributions under enhanced haze pollution events: effect of the regional transport of different aerosol types over eastern China

    Science.gov (United States)

    Sun, Tianze; Che, Huizheng; Qi, Bing; Wang, Yaqiang; Dong, Yunsheng; Xia, Xiangao; Wang, Hong; Gui, Ke; Zheng, Yu; Zhao, Hujia; Ma, Qianli; Du, Rongguang; Zhang, Xiaoye

    2018-03-01

    The climatological variation of aerosol properties and the planetary boundary layer (PBL) during 2013-2015 over the Yangtze River Delta (YRD) region were investigated by employing ground-based Micro Pulse Lidar (MPL) and CE-318 sun-photometer observations. Combining Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite products, enhanced haze pollution events affected by different types of aerosol over the YRD region were analyzed through vertical structures, spatial distributions, backward trajectories, and the potential source contribution function (PSCF) model. The results show that aerosols in the YRD are dominated by fine-mode particles, except in March. The aerosol optical depth (AOD) in June and September is higher due to high single scattering albedo (SSA) from hygroscopic growth, but it is lower in July and August due to wet deposition from precipitation. The PBL height (PBLH) is greater (means ranging from 1.23 to 1.84 km) and more variable in the warmer months of March to August, due to the stronger diurnal cycle and exchange of heat. Northern fine-mode pollutants are brought to the YRD at a height of 1.5 km. The SSA increases, blocking the radiation to the surface, and cooling the surface, thereby weakening turbulence, lowering the PBL, and in turn accelerating the accumulation of pollutants, creating a feedback to the cooling effect. Originated from the deserts in Xinjiang and Inner Mongolia, long-range transported dust masses are seen at heights of about 2 km over the YRD region with an SSA440 nm below 0.84, which heat air and raise the PBL, accelerating the diffusion of dust particles. Regional transport from biomass-burning spots to the south of the YRD region bring mixed aerosol particles at a height below 1.5 km, resulting in an SSA440 nm below 0.89. During the winter, the accumulation of the local emission layer is facilitated by stable weather conditions

  1. Aerosol optical characteristics and their vertical distributions under enhanced haze pollution events: effect of the regional transport of different aerosol types over eastern China

    Directory of Open Access Journals (Sweden)

    T. Sun

    2018-03-01

    Full Text Available The climatological variation of aerosol properties and the planetary boundary layer (PBL during 2013–2015 over the Yangtze River Delta (YRD region were investigated by employing ground-based Micro Pulse Lidar (MPL and CE-318 sun-photometer observations. Combining Moderate Resolution Imaging Spectroradiometer (MODIS and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO satellite products, enhanced haze pollution events affected by different types of aerosol over the YRD region were analyzed through vertical structures, spatial distributions, backward trajectories, and the potential source contribution function (PSCF model. The results show that aerosols in the YRD are dominated by fine-mode particles, except in March. The aerosol optical depth (AOD in June and September is higher due to high single scattering albedo (SSA from hygroscopic growth, but it is lower in July and August due to wet deposition from precipitation. The PBL height (PBLH is greater (means ranging from 1.23 to 1.84 km and more variable in the warmer months of March to August, due to the stronger diurnal cycle and exchange of heat. Northern fine-mode pollutants are brought to the YRD at a height of 1.5 km. The SSA increases, blocking the radiation to the surface, and cooling the surface, thereby weakening turbulence, lowering the PBL, and in turn accelerating the accumulation of pollutants, creating a feedback to the cooling effect. Originated from the deserts in Xinjiang and Inner Mongolia, long-range transported dust masses are seen at heights of about 2 km over the YRD region with an SSA440 nm below 0.84, which heat air and raise the PBL, accelerating the diffusion of dust particles. Regional transport from biomass-burning spots to the south of the YRD region bring mixed aerosol particles at a height below 1.5 km, resulting in an SSA440 nm below 0.89. During the winter, the accumulation of the local emission layer is facilitated by

  2. Physicochemical and toxicological characteristics of urban aerosols during a recent Indonesian biomass burning episode.

    Science.gov (United States)

    Pavagadhi, Shruti; Betha, Raghu; Venkatesan, Shriram; Balasubramanian, Rajasekhar; Hande, Manoor Prakash

    2013-04-01

    Air particulate matter (PM) samples were collected in Singapore from 21 to 29 October 2010. During this time period, a severe regional smoke haze episode lasted for a few days (21-23 October). Physicochemical and toxicological characteristics of both haze and non-haze aerosols were evaluated. The average mass concentration of PM2.5 (PM with aerodynamic diameter of ≤2.5 μm) increased by a factor of 4 during the smoke haze period (107.2 μg/m(3)) as compared to that during the non-smoke haze period (27.0 μg/m(3)). The PM2.5 samples were analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs) listed by the United States Environmental Protection Agency and 10 transition metals. Out of the seven PAHs known as potential or suspected carcinogens, five were found in significantly higher levels in smoke haze aerosols as compared to those in the background air. Metal concentrations were also found to be higher in haze aerosols. Additionally, the toxicological profile of the PM2.5 samples was evaluated using a human epithelial lung cell line (A549). Cell viability and death counts were measured after a direct exposure of PM2.5 samples to A459 cells for a period of 48 h. The percentage of metabolically active cells decreased significantly following a direct exposure to PM samples collected during the haze period. To provide further insights into the toxicological characteristics of the aerosol particles, glutathione levels, as an indirect measure of oxidative stress and caspase-3/7 levels as a measure of apoptotic death, were also evaluated.

  3. Microplastic Distribution at Different Sediment Depths in an Urban Estuary

    Directory of Open Access Journals (Sweden)

    Kathryn A. Willis

    2017-12-01

    Full Text Available As plastic production increases, so to do the threats from plastic pollution. Microplastics (defined as plastics <5 mm are a subset of marine debris about which we know less than we do of larger debris items, though they are potentially ubiquitous in the marine environment. To quantify the distribution and change in microplastic densities through time, we sampled sediment cores from an estuary in Tasmania, Australia. We hypothesized that the type, distribution and abundance of microplastics observed would be associated with increasing plastic production, coastal population growth, and proximity to urban water outflows and local hydrodynamics. Sediments ranging from the year 1744 to 2004 were sub-sampled from each core. We observed microplastics in every sample, with greater plastic frequencies found in the upper (more recent sediments. This time trend of microplastic accumulation matched that of global plastic production and coastal population growth. We observed that fibers were the most abundant type of microplastic in our samples. These fibers were present in sediments that settled prior to the presence of plastics in the environment. We propose a simple statistical model to estimate the level of contamination in our samples. We suggest that the current trend in the literature suggesting very high loads of fibers, particularly in remote locations such as the deep seafloor, may be largely due to contamination.

  4. Levels and Speciation of Platinum in Size-Fractionated Atmospheric Aerosol in Urban and Rural Sites across Europe

    Science.gov (United States)

    Shafer, Martin; Antkiewicz, Dagmara; Overdier, Joel; Schauer, James

    2016-04-01

    In this study we characterized the levels and speciation of platinum in a unique set of size-resolved atmospheric aerosol (PM) samples obtained from urban environments across Europe. From April-July 2012 we collected PM from roadside canyon, roadside motorway, and background urban sites in each of six European cities (Amsterdam, Frankfurt, London, Milan, Stockholm, and Thessaloniki). A Hi-Vol sampler was used to collect PM in three size classes (>PM7, PM7-PM3, PM3) and characterized for total platinum, soluble platinum (in a suite of physiologically relevant fluids - lung fluid (ALF), Gambles saline, 0.07M HCl, and MQ) and speciated forms (colloidal and anionic) within the soluble fractions. In addition we measured 50 other elements by SF-ICPMS, soluble ions by IC, and soluble organic carbon in the PM. Order-of-magnitude differences in air concentrations of total platinum were observed between urban sites, ranging from 4 to over 45 pg/m3; with a median level of 6 pg/m3. When platinum concentrations are normalized to PM mass the cross Europe and site-to-site variability was substantially reduced - a 3-fold variation from 200 to 600 ng/g was observed. Roadside canyon sites in London, Stockholm and Thessaloniki exhibited the highest concentrations; however levels at urban background sites were remarkably similar across the cities. Relatively consistent and low concentrations (1 to 2 pg/m3) of total platinum were observed at rural background sites across Europe. The contribution of coarse particles (>7 micron and 7-3 micron) to air concentrations of total platinum was very significant (>35% at nearly all sites). Soluble platinum fractions ranged from 2 to 6% (MQ to HCl) in rural background sites to 5 to 20% (MQ to HCl) in roadway canyon sites in London and Thessaloniki; with the extractable platinum fractions a strong function of pH. With the exception of urban canyon sites in London and Thessaloniki, soluble platinum concentrations in the fine aerosol (PM3) were all

  5. Network Capacity Assessment of CHP-based Distributed Generation on Urban Energy Distribution Networks

    Science.gov (United States)

    Zhang, Xianjun

    The combined heat and power (CHP)-based distributed generation (DG) or dis-tributed energy resources (DERs) are mature options available in the present energy market, considered to be an effective solution to promote energy efficiency. In the urban environment, the electricity, water and natural gas distribution networks are becoming increasingly interconnected with the growing penetration of the CHP-based DG. Subsequently, this emerging interdependence leads to new topics meriting serious consideration: how much of the CHP-based DG can be accommodated and where to locate these DERs, and given preexisting constraints, how to quantify the mutual impacts on operation performances between these urban energy distribution networks and the CHP-based DG. The early research work was conducted to investigate the feasibility and design methods for one residential microgrid system based on existing electricity, water and gas infrastructures of a residential community, mainly focusing on the economic planning. However, this proposed design method cannot determine the optimal DG sizing and siting for a larger test bed with the given information of energy infrastructures. In this context, a more systematic as well as generalized approach should be developed to solve these problems. In the later study, the model architecture that integrates urban electricity, water and gas distribution networks, and the CHP-based DG system was developed. The proposed approach addressed the challenge of identifying the optimal sizing and siting of the CHP-based DG on these urban energy networks and the mutual impacts on operation performances were also quantified. For this study, the overall objective is to maximize the electrical output and recovered thermal output of the CHP-based DG units. The electricity, gas, and water system models were developed individually and coupled by the developed CHP-based DG system model. The resultant integrated system model is used to constrain the DG's electrical

  6. Distribution of radionuclides in urban areas and their removal

    International Nuclear Information System (INIS)

    Roed, J.; Andersson, K.G.; Garger, E.; Sobotovitch, E.; Matveenko, I.I.

    1996-01-01

    The major contamination processes in the urban environment are wet and dry deposition with the former leading to much greater deposition per unit of time. Typical deposition patterns for radiocesium in urban areas have been identified for these processes and recent in situ measurements have been used to verify these relations and to investigate the urban weathering effect over long periods. The results of a recent series of field trials of decontamination methods in urban or suburban Russian areas are reported, and this experience has been incorporated in an example of formation of strategies for clean-up in an urban contamination scenario

  7. Bimodal Nanoparticle Size Distributions Produced by Laser Ablation of Microparticles in Aerosols

    International Nuclear Information System (INIS)

    Nichols, William T.; Malyavanatham, Gokul; Henneke, Dale E.; O'Brien, Daniel T.; Becker, Michael F.; Keto, John W.

    2002-01-01

    Silver nanoparticles were produced by laser ablation of a continuously flowing aerosol of microparticles in nitrogen at varying laser fluences. Transmission electron micrographs were analyzed to determine the effect of laser fluence on the nanoparticle size distribution. These distributions exhibited bimodality with a large number of particles in a mode at small sizes (3-6-nm) and a second, less populated mode at larger sizes (11-16-nm). Both modes shifted to larger sizes with increasing laser fluence, with the small size mode shifting by 35% and the larger size mode by 25% over a fluence range of 0.3-4.2-J/cm 2 . Size histograms for each mode were found to be well represented by log-normal distributions. The distribution of mass displayed a striking shift from the large to the small size mode with increasing laser fluence. These results are discussed in terms of a model of nanoparticle formation from two distinct laser-solid interactions. Initially, laser vaporization of material from the surface leads to condensation of nanoparticles in the ambient gas. Material evaporation occurs until the plasma breakdown threshold of the microparticles is reached, generating a shock wave that propagates through the remaining material. Rapid condensation of the vapor in the low-pressure region occurs behind the traveling shock wave. Measurement of particle size distributions versus gas pressure in the ablation region, as well as, versus microparticle feedstock size confirmed the assignment of the larger size mode to surface-vaporization and the smaller size mode to shock-formed nanoparticles

  8. Particle size distribution of aerosols sprayed from household hand-pump sprays containing fluorine-based and silicone-based compounds.

    Science.gov (United States)

    Kawakami, Tsuyoshi; Isama, Kazuo; Ikarashi, Yoshiaki

    2015-01-01

    Japan has published safety guideline on waterproof aerosol sprays. Furthermore, the Aerosol Industry Association of Japan has adopted voluntary regulations on waterproof aerosol sprays. Aerosol particles of diameter less than 10 µm are considered as "fine particles". In order to avoid acute lung injury, this size fraction should account for less than 0.6% of the sprayed aerosol particles. In contrast, the particle size distribution of aerosols released by hand-pump sprays containing fluorine-based or silicone-based compounds have not been investigated in Japan. Thus, the present study investigated the aerosol particle size distribution of 16 household hand-pump sprays. In 4 samples, the ratio of fine particles in aerosols exceeded 0.6%. This study confirmed that several hand-pump sprays available in the Japanese market can spray fine particles. Since the hand-pump sprays use water as a solvent and their ingredients may be more hydrophilic than those of aerosol sprays, the concepts related to the safety of aerosol-sprays do not apply to the hand pump sprays. Therefore, it may be required for the hand-pump spray to develop a suitable method for evaluating the toxicity and to establish the safety guideline.

  9. INDOOR-OUTDOOR AEROSOL CONCENTRATIONS IN TWO PORTUGUESE CITIES AND THE GLOBAL WARMING SCENARIO

    Energy Technology Data Exchange (ETDEWEB)

    Antonio F. Miguel; A. Heitor Reis [Department of Physics, University of Evora (Portugal); Marta Melgao [Geophysics Centre of Evora (Portugal)

    2008-09-30

    Aerosols play a major role both in climate change and in air quality. They affect climate through interfering with radiative transfer and hence the atmospheric temperature, and also the air quality. Many epidemiological studies have confirmed that a relation exists between elevated aerosol particle concentration and adverse human health effects. Aerosol particle number and size distributions were measured both indoors and outdoors in the urban areas of Evora and Lisbon. We investigated the indoor-to-outdoor relationship of aerosol particles and the aerosol size distributions. The impact of the occurrence of a residential fire in the aerosol size distribution is also analyzed. Finally, we speculate of how global increase in temperature can affect concentration of aerosols in the atmosphere, via increased boundary layer convection.

  10. Factors influencing non-native tree species distribution in urban landscapes

    Science.gov (United States)

    Wayne C. Zipperer

    2010-01-01

    Non-native species are presumed to be pervasive across the urban landscape. Yet, we actually know very little about their actual distribution. For this study, vegetation plot data from Syracuse, NY and Baltimore, MD were used to examine non-native tree species distribution in urban landscapes. Data were collected from remnant and emergent forest patches on upland sites...

  11. The aerosol distribution in Europe derived with the Community Multiscale Air Quality (CMAQ) model: comparison to near surface in situ and sunphotometer measurements

    OpenAIRE

    Matthias , V.

    2008-01-01

    The aerosol distribution in Europe was simulated with the Community Multiscale Air Quality (CMAQ) model system version 4.5 for the years 2000 and 2001. The results were compared with daily averages of PM10 measurements taken in the framework of EMEP and with aerosol optical depth (AOD) values measured within AERONET. The modelled total aerosol mass is typically about 30–60% lower than the corresponding measurements. However a comparison of the chemical composition of th...

  12. Diurnal spatial distributions of aerosol optical and cloud micro-macrophysics properties in Africa based on MODIS observations

    Science.gov (United States)

    Ntwali, Didier; Chen, Hongbin

    2018-06-01

    The diurnal spatial distribution of both natural and anthropogenic aerosols, as well as liquid and ice cloud micro-macrophysics have been evaluated over Africa using Terra and Aqua MODIS collection 6 products. The variability of aerosol optical depth (AOD), Ångström exponent (AE), liquid and ice cloud microphysics (Liquid cloud effective radius LCER, Ice cloud effective radius ICER) and cloud macrophysics (Liquid cloud optical thickness LCOT, Liquid cloud water path LCWP, Ice cloud optical thickness ICOT, Ice cloud water path ICWP) parameters were investigated from the morning to afternoon over Africa from 2010 to 2014. In both the morning (Terra) and afternoon (Aqua) heavy pollution (AOD ≥ 0.6) occurs in the coastal and central areas (between 120 N-170 N and 100 E-150 E) of West of Africa (WA), Central of Africa (CA) (0.50 S-70S and 100 E-250 E),. Moderate pollution (0.3 1.2) aerosols. The mixture of dust and biomass burning aerosols (0.7 improve aerosol and cloud remote sensing retrieval.

  13. Influences of natural emission sources (wildfires and Saharan dust) on the urban organic aerosol in Barcelona (Western Mediterranean Basis) during a PM event.

    Science.gov (United States)

    van Drooge, Barend L; Lopez, Jordi F; Grimalt, Joan O

    2012-11-01

    The urban air quality in Barcelona in the Western Mediterranean Basin is characterized by overall high particulate matter (PM) concentrations, due to intensive local anthropogenic emissions and specific meteorological conditions. Moreover, on several days, especially in summer, natural PM sources, such as long-range transported Saharan dust from Northern Africa or wildfires on the Iberian Peninsula and around the Mediterranean Basin, may influence the levels and composition of the organic aerosol. In the second half of July 2009, daily collected PM(10) filter samples in an urban background site in Barcelona were analyzed on organic tracer compounds representing several emission sources. During this period, an important PM peak event was observed. Individual organic compound concentrations increased two to five times during this event. Although highest increase was observed for the organic tracer of biomass burning, the contribution to the organic aerosol was estimated to be around 6 %. Organic tracers that could be related to Saharan dust showed no correlation with the PM and OC levels, while this was the case for those related to fossil fuel combustion from traffic emissions. Moreover, a change in the meteorological conditions gave way to an overall increase of the urban background contamination. Long-range atmospheric transport of organic compounds from primary emissions sources (i.e., wildfires and Saharan dust) has a relatively moderate impact on the organic aerosol in an urban area where the local emissions are dominating.

  14. Assessment of Aerosol Distributions from GEOS-5 Using the CALIPSO Feature Mask

    Science.gov (United States)

    Welton, Ellsworth

    2010-01-01

    A-train sensors such as MODIS, MISR, and CALIPSO are used to determine aerosol properties, and in the process a means of estimating aerosol type (e.g. smoke vs. dust). Correct classification of aerosol type is important for climate assessment, air quality applications, and for comparisons and analysis with aerosol transport models. The Aerosols-Clouds-Ecosystems (ACE) satellite mission proposed in the NRC Decadal Survey describes a next generation aerosol and cloud suite similar to the current A-train, including a lidar. The future ACE lidar must be able to determine aerosol type effectively in conjunction with modeling activities to achieve ACE objectives. Here we examine the current capabilities of CALIPSO and the NASA Goddard Earth Observing System general circulation model and data assimilation system (GEOS-5), to place future ACE needs in context. The CALIPSO level 2 feature mask includes vertical profiles of aerosol layers classified by type. GEOS-5 provides global 3D aerosol mass for sulfate, sea salt, dust, and black and organic carbon. A GEOS aerosol scene classification algorithm has been developed to provide estimates of aerosol mixtures and extinction profiles along the CALIPSO orbit track. In previous work, initial comparisons between GEOS-5 derived aerosol mixtures and CALIPSO derived aerosol types were presented for July 2007. In general, the results showed that model and lidar derived aerosol types did not agree well in the boundary layer. Agreement was poor over Europe, where CALIPSO indicated the presence of dust and pollution mixtures yet GEOS-5 was dominated by pollution with little dust. Over the ocean in the tropics, the model appeared to contain less sea salt than detected by CALIPSO, yet at high latitudes the situation was reserved. Agreement between CALIPSO and GEOS-5, aerosol types improved above the boundary layer, primarily in dust and smoke dominated regions. At higher altitudes (> 5 km), the model contained aerosol layers not detected

  15. Aerosol particle size distribution in the stratosphere retrieved from SCIAMACHY limb measurements

    Directory of Open Access Journals (Sweden)

    E. Malinina

    2018-04-01

    Full Text Available w can be retrieved with an uncertainty of less than 20 %. The algorithm was successfully applied to the tropical region (20° N–20° S for 10 years (2002–2012 of SCIAMACHY observations in limb-viewing geometry, establishing a unique data set. Analysis of this new climatology for the particle size distribution parameters showed clear increases in the mode radius after the tropical volcanic eruptions, whereas no distinct behaviour of the absolute distribution width could be identified. A tape recorder, which describes the time lag as the perturbation propagates to higher altitudes, was identified for both parameters after the volcanic eruptions. A quasi-biannual oscillation (QBO pattern at upper altitudes (28–32 km is prominent in the anomalies of the analysed parameters. A comparison of the aerosol effective radii derived from SCIAMACHY and SAGE II data was performed. The average difference is found to be around 30 % at the lower altitudes, decreasing with increasing height to almost zero around 30 km. The data sample available for the comparison is, however, relatively small.

  16. Aerosol particle measurements at three stationary sites in the megacity of Paris during summer 2009: meteorology and air mass origin dominate aerosol particle composition and size distribution

    Directory of Open Access Journals (Sweden)

    F. Freutel

    2013-01-01

    Full Text Available During July 2009, a one-month measurement campaign was performed in the megacity of Paris. Amongst other measurement platforms, three stationary sites distributed over an area of 40 km in diameter in the greater Paris region enabled a detailed characterization of the aerosol particle and gas phase. Simulation results from the FLEXPART dispersion model were used to distinguish between different types of air masses sampled. It was found that the origin of air masses had a large influence on measured mass concentrations of the secondary species particulate sulphate, nitrate, ammonium, and oxygenated organic aerosol measured with the Aerodyne aerosol mass spectrometer in the submicron particle size range: particularly high concentrations of these species (about 4 μg m−3, 2 μg m−3, 2 μg m−3, and 7 μg m−3, respectively were measured when aged material was advected from continental Europe, while for air masses originating from the Atlantic, much lower mass concentrations of these species were observed (about 1 μg m−3, 0.2 μg m−3, 0.4 μg m−3, and 1–3 μg m−3, respectively. For the primary emission tracers hydrocarbon-like organic aerosol, black carbon, and NOx it was found that apart from diurnal source strength variations and proximity to emission sources, local meteorology had the largest influence on measured concentrations, with higher wind speeds leading to larger dilution and therefore smaller measured concentrations. Also the shape of particle size distributions was affected by wind speed and air mass origin. Quasi-Lagrangian measurements performed under connected flow conditions between the three stationary sites were used to estimate the influence of the Paris emission plume onto its surroundings, which was found to be rather small. Rough estimates for the impact of the Paris emission plume on the suburban areas can be

  17. Spatial distribution of urban heat island in Hangzhou and its mitigation countermeasures

    DEFF Research Database (Denmark)

    Wang, W.-W.; Li, G.-L.; Xue, J.

    2009-01-01

    of the evolution of urban landuse types, the changes of urban spatial pattern, the rationality of the urban land layout, and the emission of anthropogenic heat. Finally, in the perspective of urban planning, some mitigation countermeasures including the reasonable control of the expansion of urban landuse......, construction of the urban ecological open space, optimization of the layout of urban landuse, and planning for underlaying surface were put forward. This aims to provide a reference to work in improving the thermal environment of Hangzhou City.......Taking Hangzhou City in summer as a case, the thermal infrared remote sensing image (Landsat 5 TM) was used to extract and inverse the surface land cover types and surface temperature of Hangzhou City. The spatial distribution characteristics of urban heat island was analyzed in the city...

  18. Fractal-based exponential distribution of urban density and self-affine fractal forms of cities

    International Nuclear Information System (INIS)

    Chen Yanguang; Feng Jian

    2012-01-01

    Highlights: ► The model of urban population density differs from the common exponential function. ► Fractal landscape influences the exponential distribution of urban density. ► The exponential distribution of urban population suggests a self-affine fractal. ► Urban space can be divided into three layers with scaling and non-scaling regions. ► The dimension of urban form with characteristic scale can be treated as 2. - Abstract: Urban population density always follows the exponential distribution and can be described with Clark’s model. Because of this, the spatial distribution of urban population used to be regarded as non-fractal pattern. However, Clark’s model differs from the exponential function in mathematics because that urban population is distributed on the fractal support of landform and land-use form. By using mathematical transform and empirical evidence, we argue that there are self-affine scaling relations and local power laws behind the exponential distribution of urban density. The scale parameter of Clark’s model indicating the characteristic radius of cities is not a real constant, but depends on the urban field we defined. So the exponential model suggests local fractal structure with two kinds of fractal parameters. The parameters can be used to characterize urban space filling, spatial correlation, self-affine properties, and self-organized evolution. The case study of the city of Hangzhou, China, is employed to verify the theoretical inference. Based on the empirical analysis, a three-ring model of cities is presented and a city is conceptually divided into three layers from core to periphery. The scaling region and non-scaling region appear alternately in the city. This model may be helpful for future urban studies and city planning.

  19. The fluorescence properties of aerosol larger than 0.8 μm in urban and tropical rainforest locations

    Directory of Open Access Journals (Sweden)

    A. M. Gabey

    2011-06-01

    Full Text Available UV-LIF measurements were performed on ambient aerosol in Manchester, UK (urban city centre, winter and Borneo, Malaysia (remote, tropical using a Wide Issue Bioaerosol Spectrometer, version 3 (WIBS3. These sites are taken to represent environments with minor and significant primary biological aerosol (PBA influences respectively, and the urban dataset describes the fluorescent background aerosol against which PBA must be identified by researchers using LIF. The ensemble aerosol at both sites was characterised over 2–3 weeks by measuring the fluorescence intensity and optical equivalent diameter (DP of single particles sized 0.8 ≤ DP ≤ 20 μm. Filter samples were also collected for a subset of the Manchester campaign and analysed using energy dispersive X-Ray (EDX spectroscopy and environmental scanning electron microscopy (ESEM, which revealed mostly non-PBA at D ≤ 1 μm.

    The WIBS3 features three fluorescence channels: the emission following a 280 nm excitation is recorded at 310–400 nm (channel F1 and 400–600 nm (F2, and fluorescence excited at 350 nm is detected at 400–600 nm (F3. In Manchester the primary size mode of fluorescent and non-fluorescent material was present at 0.8–1.2 μm, with a secondary fluorescent mode at 2–4 μm. In Borneo non-fluorescent material peaked at 0.8–1.2 μm and fluorescent at 3–4 μm. Agreement between fluorescent number concentrations in each channel differed at the two sites, with F1 and F3 reporting similar concentrations in Borneo but F3 outnumbering F1 by a factor of 2–3 across the size spectrum in Manchester.

    The fluorescence intensity in each channel generally rose with DP at both sites with the exception of F1 intensity in Manchester, which peaked at DP = 4 μm, causing a divergence between F1 and F3 intensity at larger DP. This divergence and the differing

  20. Seasonal and spatial variability of the organic matter-to-organic carbon mass ratios in Chinese urban organic aerosols and a first report of high correlations between aerosol oxalic acid and zinc

    Science.gov (United States)

    Xing, L.; Fu, T.-M.; Cao, J. J.; Lee, S. C.; Wang, G. H.; Ho, K. F.; Cheng, M.-C.; You, C.-F.; Wang, T. J.

    2013-01-01

    We calculated the organic matter to organic carbon mass ratios (OM/OC mass ratios) in PM2.5 collected from 14 Chinese cities during summer and winter of 2003 and analyzed the causes for their seasonal and spatial variability. The OM/OC mass ratios were calculated two ways. Using a mass balance method, the calculated OM/OC mass ratios averaged 1.92 ± 0.39 yr-round, with no significant seasonal or spatial variation. The second calculation was based on chemical species analyses of the organic compounds extracted from the PM2.5 samples using dichloromethane/methanol and water. The calculated OM/OC mass ratio in summer was relatively high (1.75 ± 0.13) and spatially-invariant, due to vigorous photochemistry and secondary OA production throughout the country. The calculated OM/OC mass ratio in winter (1.59 ± 0.18) was significantly lower than that in summer, with lower values in northern cities (1.51 ± 0.07) than in southern cities (1.65 ± 0.15). This likely reflects the wider usage of coal for heating purposes in northern China in winter, in contrast to the larger contributions from biofuel and biomass burning in southern China in winter. On average, organic matters constituted 36% and 34% of Chinese urban PM2.5 mass in summer and winter, respectively. We reported, for the first time, high correlations between Zn and oxalic acid in Chinese urban aerosols in summer. This is consistent with the formation of stable Zn oxalate complex in the aerosol phase previously proposed by Furukawa and Takahashi (2011). We found that many other dicarboxylic acids were also highly correlated with Zn in the summer Chinese urban aerosol samples, suggesting that they may also form stable organic complexes with Zn. Such formation may have profound implications for the atmospheric abundance and hygroscopic property of aerosol dicarboxylic acids.

  1. Size distributions of various radioactive aerosols in the ground-level atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Schumann, G.; Baust, E.

    1963-11-15

    To know the size spectra of radioactive aerosols is important for many reasons. Among others, the efficiency of measuring devices or biological processes, as for instance, retention in the lungs, depend on particle size.The work described deals mainly with two different components of radioactive aerosols in the atmosphere: the natural radon daughters and the fission products originating from nuclear test explosions.

  2. Biomass burning contributions to urban aerosols in a coastal Mediterranean City

    NARCIS (Netherlands)

    Reche, C.; Viana, M.; Amato, F.; Alastuey, A.; Moreno, T.; Hillamo, R.; Teinilä, K.; Saarnio, K.; Seco, R.; Peñuelas, J.; Mohr, C.; Prévôt, A.S.H.; Querol, X.

    2012-01-01

    Mean annual biomass burning contributions to the bulk particulate matter (PM X) load were quantified in a southern-European urban environment (Barcelona, Spain) with special attention to typical Mediterranean winter and summer conditions. In spite of the complexity of the local air pollution

  3. Oxidative potential of ambient fine aerosol over a semi-urban site in the Indo-Gangetic Plain

    Science.gov (United States)

    Patel, Anil; Rastogi, Neeraj

    2018-02-01

    Indo-Gangetic Plain (IGP) receives emissions from variety of pollutant sources such as post-harvest crop residue burning, vehicles, industries, power plants, and bio-fuel burning. Several studies have documented physical, chemical and optical properties of aerosol over the IGP; however, their oxidative potential (OP) has not yet documented. Present study reports the OP (measured through dithiothreitol (DTT) assay) of soluble particulate matter smaller than 2.5 μm aerodynamic diameter (PM2.5) over Patiala (30.3°N, 76.4°E, 249 m amsl), a semi-urban site located in the IGP, during winter 2014. Volume-normalized OP (range: 1.3-7.2 nmol DTT min-1 m-3, average: 3.8 ± 1.4, 1σ) is found to be ∼3 to 20 times higher, and mass-normalized OP (range: 13-50 pmol DTT min-1 μg-1, average: 27 ± 8, 1σ) is found to be similar or higher than those documented in literature. Further, observed OP is found to depend more on PM2.5 composition rather than mass concentration. Mass fractions of organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon (WSOC) correlate positively whereas that of secondary inorganic aerosol (SIA, sum of the concentrations of SO42-, NO3- and NH4+) correlate negatively with OP μg-1 at considerable significance level (p < 0.05). Negative correlation of SIA with OP μg-1 has been assessed in laboratory experiment and attributed to their DTT inactive nature. It is suggested to use WSOC/SIA ratio as a measure of DTT activity of secondary particles over the study region. Further, biomass burning derived species are observed to be more DTT active than those derived from fossil fuel burning. It was also observed that the slope of OP μg-1 and WSOC/SIA ratio linear relationship enhances significantly in samples collected during days following foggy nights in comparison to that in samples collected during non-foggy period, which may be due to the production of redox-active species by fog processing. Such studies have implications in assessing

  4. Variability of atmospheric aerosols at urban, regional and continental backgrounds in the western mediterranean basin

    OpenAIRE

    Pérez Lozano, Noemí

    2010-01-01

    Descripció del recurs: el 14 de febrer de 2011 El estudio de los niveles y composición del material particulado atmosférico (PM) medido simultáneamente en diferentes ambientes a escala regional se llevó a cabo en la cuenca del Mediterráneo Occidental con el fin de entender las fuentes y patrones de transformación y transporte de aerosoles en esta zona. Para esto, la medida de niveles y caracterización química de PM10, PM2.5 y PM1 se llevó a cabo en tres estaciones de monitoreo: Montsec (MS...

  5. Application of PIXE analysis to study urban atmospheric aerosols from downtown Havana City

    International Nuclear Information System (INIS)

    Perez Zayas, Grizel; Pinnera Hernandez, Ibrahin; Ramos Aruca, Maridelin; Guibert Gala, Rolando; Molina Esquivel, Enrique; Martinez Varona, Miriam; Fernandez Arocha, Ariadna; Aldape Ugalde, Francisca; Flores Maldonado, Javier

    2010-01-01

    The present work reports, the results of a first study of elemental composition in airborne particulate matter (in fine and coarse particle size fractions) collected at the Atmospheric Monitoring Station in the Municipality of Centro Habana, using the Particle-Induced X-ray Emission (PIXE) technique. At present, there is not information available about elements contents in airborne particulate matter from this region. For this study, we carried out a sampling campaign during five months (November 14, 2006 to April 19, 2007). The samples were collected every second day during 24 h under an air flux of 20 l/min. The air sampler used was a Gent Sampler equipped with a Stacked Filter Unit (SFU) system which allows the aerosol collection in both size fractions simultaneously. A total of 144 aerosol samples were collected (72 correspond to the fine mass particle and 72 to the coarse mass particle). For PIXE analysis, the samples were irradiated by 2.5 MeV energy protons from the 2MV Van de Graff Tandetron Accelerator from the Laboratory of PIXE analysis at ININ, Mexico. A total of 14 elements (S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br and Pb) were consistently detected in both particle size fractions with minimum detection limits in the range of 1-10 ng/m3. The quantitative results obtained from PIXE elemental analysis for mass of particles in both fractions have revealed important information that has been used in a first attempt to understand and to characterize the atmospheric pollution of this area. A general discussion about these results is presented in this paper. (author)

  6. Application of PIXE analysis to study urban atmospheric aerosols from downtown Havana City

    International Nuclear Information System (INIS)

    Perez Zayas, Grizel; Pinnera Hernandez, Ibrahin; Ramos Aruca, Maridelin; Guibert Gala, Rolando; Molina Esquivel, Enrique; Martinez Varona, Miriam; Fernandez Arocha, Ariadna; Aldape Ugalde, Francisca; Flores Maldonado, Javier

    2009-01-01

    The present work reports, the results of a first study of elemental composition in airborne particulate matter (in fine and coarse particle size fractions) collected at the Atmospheric Monitoring Station in the Municipality of Centro Habana, using the Particle-Induced X-ray Emission (PIXE) technique. At present, there is not information available about elements contents in airborne particulate matter from this region. For this study, we carried out a sampling campaign during five months (November 14, 2006 to April 19, 2007). The samples were collected every second day during 24 h under an air flux of 20 l/min. The air sampler used was a Gent Sampler equipped with a Stacked Filter Unit (SFU) system which allows the aerosol collection in both size fractions simultaneously. A total of 144 aerosol samples were collected (72 correspond to the fine mass particle and 72 to the coarse mass particle). For PIXE analysis, the samples were irradiated by 2.5 MeV energy protons from the 2MV Van de Graff Tandetron Accelerator from the Laboratory of PIXE analysis at ININ, Mexico. A total of 14 elements (S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br and Pb) were consistently detected in both particle size fractions with minimum detection limits in the range of 1-10 ng/m3. The quantitative results obtained from PIXE elemental analysis for mass of particles in both fractions have revealed important information that has been used in a first attempt to understand and to characterize the atmospheric pollution of this area. A general discussion about these results is presented in this paper. (author)

  7. Secondary organic aerosol origin in an urban environment: influence of biogenic and fuel combustion precursors.

    Science.gov (United States)

    Minguillón, M C; Pérez, N; Marchand, N; Bertrand, A; Temime-Roussel, B; Agrios, K; Szidat, S; van Drooge, B; Sylvestre, A; Alastuey, A; Reche, C; Ripoll, A; Marco, E; Grimalt, J O; Querol, X

    2016-07-18

    Source contributions of organic aerosol (OA) are still not fully understood, especially in terms of quantitative distinction between secondary OA formed from anthropogenic precursors vs. that formed from natural precursors. In order to investigate the OA origin, a field campaign was carried out in Barcelona in summer 2013, including two periods characterized by low and high traffic conditions. Volatile organic compound (VOC) concentrations were higher during the second period, especially aromatic hydrocarbons related to traffic emissions, which showed a marked daily cycle peaking during traffic rush hours, similarly to black carbon (BC) concentrations. Biogenic VOC (BVOC) concentrations showed only minor changes from the low to the high traffic period, and their intra-day variability was related to temperature and solar radiation cycles, although a decrease was observed for monoterpenes during the day. The organic carbon (OC) concentrations increased from the first to the second period, and the fraction of non-fossil OC as determined by (14)C analysis increased from 43% to 54% of the total OC. The combination of (14)C analysis and Aerosol Chemical Speciation Monitor (ACSM) OA source apportionment showed that the fossil OC was mainly secondary (>70%) except for the last sample, when the fossil secondary OC only represented 51% of the total fossil OC. The fraction of non-fossil secondary OC increased from 37% of total secondary OC for the first sample to 60% for the last sample. This enhanced formation of non-fossil secondary OA (SOA) could be attributed to the reaction of BVOC precursors with NOx emitted from road traffic (or from its nocturnal derivative nitrate that enhances night-time semi-volatile oxygenated OA (SV-OOA)), since NO2 concentrations increased from 19 to 42 μg m(-3) from the first to the last sample.

  8. Changes in column aerosol optical properties during extreme haze-fog episodes in January 2013 over urban Beijing.

    Science.gov (United States)

    Yu, Xingna; Kumar, K Raghavendra; Lü, Rui; Ma, Jia

    2016-03-01

    Several dense haze-fog (HF) episodes were occurred in the North China Plain (NCP), especially over Beijing in January 2013 characterized by a long duration, a large influential region, and an extremely high PM2.5 values (>500 μg m(-3)). In this study, we present the characteristics of aerosol optical properties and radiative forcing using Cimel sun-sky radiometer measurements during HF and no haze-fog (NHF) episodes occurred over Beijing during 1-31 January, 2013. The respective maximum values of daily mean aerosol optical depth at 440 nm (AOD440) were observed to be 1.21, 1.43, 1.52, and 2.21 occurred on 12, 14 19, and 28 January. It was found that the Ångström exponent (AE) values were almost higher than 1.0 during all the days with its maximum on 26 January (1.53), suggests the dominance of fine-mode particles. The maximum (minimum) aerosol volume size distributions occurred during dense HF (NHF) days with larger particle volumes of fine-mode. The single scattering albedo, asymmetry parameter, and complex refractive index values during HF events suggest the abundance of fine-mode particles from anthropogenic (absorbing) activities mixed with scattering dust particles. The average shortwave direct aerosol radiative forcing (DARF) values at the bottom-of-atmosphere (BOA) during HF and NHF days were estimated to be 112.29 ± 42.18 W m(-2) and -58.61 ± 13.09 W m(-2), while at the top-of-atmosphere (TOA) the forcing values were -45.78 ± 22.17 W m(-2) and -18.64 ± 5.84 W m(-2), with the corresponding heating rate of 1.61 ± 0.48 K day(-1) and 1.12 ± 0.31 K day(-1), respectively. The DARF values retrieved from the AERONET were in good agreement with the SBDART computed both at the TOA (r = 0.95) and the BOA (r = 0.97) over Beijing in January 2013. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. PIXE identification of fine and coarse particles of aerosol samples and their distribution across Beirut

    Energy Technology Data Exchange (ETDEWEB)

    Roumie, M., E-mail: mroumie@cnrs.edu.lb [Accelerator Laboratory, Lebanese Atomic Energy Commission, National Council for Scientific Research, P.O. Box 11-8281, Beirut (Lebanon); Saliba, N., E-mail: ns30@aub.edu.lb [Department of Chemistry, Faculty of Arts and Sciences, American University of Beirut, Beirut (Lebanon); Nsouli, B., E-mail: bnsouli@cnrs.edu.lb [Accelerator Laboratory, Lebanese Atomic Energy Commission, National Council for Scientific Research, P.O. Box 11-8281, Beirut (Lebanon); Younes, M., E-mail: myriam_younis@hotmail.com [Accelerator Laboratory, Lebanese Atomic Energy Commission, National Council for Scientific Research, P.O. Box 11-8281, Beirut (Lebanon); Noun, M., E-mail: manale_noun@hotmail.com [Accelerator Laboratory, Lebanese Atomic Energy Commission, National Council for Scientific Research, P.O. Box 11-8281, Beirut (Lebanon); Massoud, R., E-mail: rm84@aub.edu.lb [Department of Chemistry, Faculty of Arts and Sciences, American University of Beirut, Beirut (Lebanon)

    2011-12-15

    This study is the first national attempt to assess the levels of PMs in Beirut city and consequently understand air pollution distribution. Aerosol sampling was carried out using three PM{sub 10} and three PM{sub 2.5} samplers which were installed at three locations lying along the SE-NW direction over Beirut. The sampling of PM{sub 10} and PM{sub 2.5} was done during a period extending from May till December 2009. The random collection of the particles (1 in 6 days) was carried out on Teflon filters, for a period of 24-h. The elemental analysis of particulate matter was performed using proton induced X-ray emission technique PIXE at the Lebanese 1.7 MV Tandem-Pelletron accelerator of Beirut. Na, Mg, Al, Si, P, S and Cl were quantified using 1 MeV proton beam, while K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn and Pb were determined using 3 MeV-energy of proton beam.

  10. Emission and chemistry of organic carbon in the gas and aerosol phase at a sub-urban site near Mexico City in March 2006 during the MILAGRO study

    Directory of Open Access Journals (Sweden)

    J. A. de Gouw

    2009-05-01

    Full Text Available Volatile organic compounds (VOCs and carbonaceous aerosol were measured at a sub-urban site near Mexico City in March of 2006 during the MILAGRO study (Megacity Initiative: Local and Global Research Objectives. Diurnal variations of hydrocarbons, elemental carbon (EC and hydrocarbon-like organic aerosol (HOA were dominated by a high peak in the early morning when local emissions accumulated in a shallow boundary layer, and a minimum in the afternoon when the emissions were diluted in a significantly expanded boundary layer and, in case of the reactive gases, removed by OH. In comparison, diurnal variations of species with secondary sources such as the aldehydes, ketones, oxygenated organic aerosol (OOA and water-soluble organic carbon (WSOC stayed relatively high in the afternoon indicating strong photochemical formation. Emission ratios of many hydrocarbon species relative to CO were higher in Mexico City than in the U.S., but we found similar emission ratios for most oxygenated VOCs and organic aerosol. Secondary formation of acetone may be more efficient in Mexico City than in the U.S., due to higher emissions of alkane precursors from the use of liquefied petroleum gas. Secondary formation of organic aerosol was similar between Mexico City and the U.S. Combining the data for all measured gas and aerosol species, we describe the budget of total observed organic carbon (TOOC, and find that the enhancement ratio of TOOC relative to CO is conserved between the early morning and mid afternoon despite large compositional changes. Finally, the influence of biomass burning is investigated using the measurements of acetonitrile, which was found to correlate with levoglucosan in the particle phase. Diurnal variations of acetonitrile indicate a contribution from local burning sources. Scatter plots of acetonitrile versus CO suggest that the contribution of biomass burning to the enhancement of most gas and aerosol species was not dominant and perhaps

  11. Emission and Chemistry of Organic Carbon in the Gas and Aerosol Phase at a Sub-Urban Site Near Mexico City in March 2006 During the MILAGRO Study

    Energy Technology Data Exchange (ETDEWEB)

    de Gouw, Joost A.; Welsh-Bon, Daniel; Warneke, Carsten; Kuster, W. C.; Alexander, M. L.; Baker, Angela K.; Beyersdorf, Andreas J.; Blake, D. R.; Canagaratna, Manjula R.; Celada, A. T.; Huey, L. G.; Junkermann, W.; Onasch, Timothy B.; Salcido, A.; Sjostedt, S. J.; Sullivan, Amy; Tanner, David J.; Vargas-Ortiz, Leroy; Weber, R. J.; Worsnop, Douglas R.; Yu, Xiao-Ying; Zaveri, Rahul A.

    2009-05-28

    Volatile organic compounds (VOCs) and carbonaceous aerosol were measured at a sub-urban site near Mexico City in March of 2006 during the MILAGRO study (Megacity Initiative: Local and Global Research Objectives). Diurnal variations of hydrocarbons, elemental carbon (EC) and hydrocarbon-like organic aerosol (HOA) were dominated by a high peak in the early morning when local emissions accumulated in a shallow boundary layer, and a minimum in the afternoon when the emissions were diluted in a significantly expanded boundary layer and, in case of the reactive gases, removed by OH. In comparison, diurnal variations of species with secondary sources such as the aldehydes, ketones, oxygenated organic aerosol (OOA) and water-soluble organic carbon (WSOC) stayed relatively high in the afternoon indicating strong photochemical formation. Emission ratios of many hydrocarbon species relative to CO were higher in Mexico City than in the U.S., but we found similar emission ratios for most oxygenated VOCs and organic aerosol. Secondary formation of acetone may be more efficient in Mexico City than in the U.S., due to higher emissions of alkane precursors from the use of liquefied petroleum gas. Secondary formation of organic aerosol was similar between Mexico City and the U.S. Combining the data for all measured gas and aerosol species, we describe the budget of total observed organic carbon (TOOC), and find that the enhancement ratio of TOOC relative to CO is conserved between the early morning and mid afternoon despite large compositional changes. Finally, the influence of biomass burning is investigated using the measurements of acetonitrile, which was found to correlate with levoglucosan in the particle phase. Diurnal variations of acetonitrile indicate a contribution from local burning sources. Scatter plots of acetonitrile versus CO suggest that the contribution of biomass burning to the enhancement of most gas and aerosol species was not dominant and perhaps not dissimilar

  12. Size distributions of hydrophilic and hydrophobic fractions of water-soluble organic carbon in an urban atmosphere in Hong Kong

    Science.gov (United States)

    Wang, Nijing; Yu, Jian Zhen

    2017-10-01

    Water-soluble organic carbon (WSOC) is a significant part of ambient aerosol and plays an active role in contributing to aerosol's effect on visibility degradation and radiation budget through its interactions with atmospheric water. Size-segregated aerosol samples in the range of 0.056-18 μm were collected using a ten-stage impactor sampler at an urban site in Hong Kong over one-year period. The WSOC samples were separated into hydrophilic (termed WSOC_h) and hydrophobic fractions (i.e., the humic-like substances (HULIS) fraction) through solid-phase extraction procedure. Carbon in HULIS accounted for 40 ± 14% of WSOC. The size distribution of HULIS was consistently characterized in all seasons with a dominant droplet mode (46-71%) and minor condensation (9.0-18%) and coarse modes (20-35%). The droplet mode had a mass median aerodynamic diameter in the range of 0.7-0.8 μm. This size mode showed the largest seasonal variation in abundance, lowest in the summer (0.41 μg/m3) and highest in the winter (3.3 μg/m3). WSOC_h also had a dominant droplet mode, but was more evenly distributed among different size modes. Inter-species correlations within the same size mode suggest that the condensation-mode HULIS was partly associated with combustion sources and the droplet-mode was strongly associated with secondary sulfate formation and biomass burning particle aging processes. There is evidence to suggest that the coarse-mode HULIS largely originated from coagulation of condensation-mode HULIS with coarse soil/sea salt particles. The formation process and possible sources of WSOC_h was more complicated and multiple than HULIS and need further investigation. Our measurements indicate that WSOC components contributed a dominant fraction of water-soluble aerosol mass in particles smaller than 0.32 μm while roughly 20-30% in the larger particles.

  13. Dependence of columnar aerosol size distribution, optical properties, and chemical components on regional transport in Beijing

    Science.gov (United States)

    Wang, Shuo; Zhao, Weixiong; Xu, Xuezhe; Fang, Bo; Zhang, Qilei; Qian, Xiaodong; Zhang, Weijun; Chen, Weidong; Pu, Wei; Wang, Xin

    2017-11-01

    Seasonal dependence of the columnar aerosol optical and chemical properties on regional transport in Beijing over 10 years (from January 2005 to December 2014) were analyzed by using the ground-based remote sensing combined with backward trajectory analysis. Daily air mass backward trajectories terminated in Beijing were computed with HYSPLIT-4 model and were categorized into five clusters. The columnar mass concentrations of black carbon (BC), brown carbon (BrC), dust (DU), aerosol water content (AW), and ammonium sulfate like aerosol (AS) of each cluster were retrieved from the optical data obtained from the Aerosol Robotic NETwork (AERONET) with five-component model. It was found that the columnar aerosol properties in different seasons were changed, and they were related to the air mass origins. In spring, aerosol was dominated by coarse particles. Summer was characterized by higher single scattering albedo (SSA), lower real part of complex refractive index (n), and obvious hygroscopic growth due to humid air from the south. During autumn and winter, there was an observable increase in absorption aerosol optical thickness (AAOT) and the imaginary part of complex refraction (k), with high levels of retrieved BC and BrC. However, concentrations of BC showed less dependence on the clusters during the two seasons owing to the widely spread coal heating in north China.

  14. Dust plume formation in the free troposphere and aerosol size distribution during the Saharan Mineral Dust Experiment in North Africa

    KAUST Repository

    Khan, Basit Ali

    2015-11-27

    Dust particles mixed in the free troposphere have longer lifetimes than airborne particles near the surface. Their cumulative radiative impact on earth’s meteorological processes and climate might be significant despite their relatively small contribution to total dust abundance. One example is the elevated dust-laden Saharan Air Layer (SAL) over the tropical and subtropical North Atlantic, which cools the sea surface. To understand the formation mechanisms of a dust layer in the free troposphere, this study combines model simulations and dust observations collected during the first stage of the Saharan Mineral Dust Experiment (SAMUM-I), which sampled dust events that extended from Morocco to Portugal, and investigated the spatial distribution and the microphysical, optical, chemical, and radiative properties of Saharan mineral dust. The Weather Research Forecast model coupled with the Chemistry/Aerosol module (WRF-Chem) is employed to reproduce the meteorological environment and spatial and size distributions of dust. The model domain covers northwest Africa and adjacent water with 5 km horizontal grid spacing and 51 vertical layers. The experiments were run from 20 May to 9 June 2006, covering the period of the most intensive dust outbreaks. Comparisons of model results with available airborne and ground-based observations show that WRF-Chem reproduces observed meteorological fields as well as aerosol distribution across the entire region and along the airplane’s tracks. Several mechanisms that cause aerosol entrainment into the free troposphere are evaluated and it is found that orographic lifting, and interaction of sea breeze with the continental outflow are key mechanisms that form a surface-detached aerosol plume over the ocean. The model dust emission scheme is tuned to simultaneously fit the observed total optical depth and the ratio of aerosol optical depths generated by fine and coarse dust modes. Comparisons of simulated dust size distributions with

  15. Dust plume formation in the free troposphere and aerosol size distribution during the Saharan Mineral Dust Experiment in North Africa

    Directory of Open Access Journals (Sweden)

    Basit Khan

    2015-11-01

    Full Text Available Dust particles mixed in the free troposphere have longer lifetimes than airborne particles near the surface. Their cumulative radiative impact on earth's meteorological processes and climate might be significant despite their relatively small contribution to total dust abundance. One example is the elevated dust-laden Saharan Air Layer (SAL over the tropical and subtropical North Atlantic, which cools the sea surface. To understand the formation mechanisms of a dust layer in the free troposphere, this study combines model simulations and dust observations collected during the first stage of the Saharan Mineral Dust Experiment (SAMUM-I, which sampled dust events that extended from Morocco to Portugal, and investigated the spatial distribution and the microphysical, optical, chemical, and radiative properties of Saharan mineral dust. The Weather Research Forecast model coupled with the Chemistry/Aerosol module (WRF-Chem is employed to reproduce the meteorological environment and spatial and size distributions of dust. The model domain covers northwest Africa and adjacent water with 5 km horizontal grid spacing and 51 vertical layers. The experiments were run from 20 May to 9 June 2006, covering the period of the most intensive dust outbreaks. Comparisons of model results with available airborne and ground-based observations show that WRF-Chem reproduces observed meteorological fields as well as aerosol distribution across the entire region and along the airplane's tracks. Several mechanisms that cause aerosol entrainment into the free troposphere are evaluated and it is found that orographic lifting, and interaction of sea breeze with the continental outflow are key mechanisms that form a surface-detached aerosol plume over the ocean. The model dust emission scheme is tuned to simultaneously fit the observed total optical depth and the ratio of aerosol optical depths generated by fine and coarse dust modes. Comparisons of simulated dust size

  16. Characterization of water-soluble organic aerosol in coastal New England: Implications of variations in size distribution

    Science.gov (United States)

    Ziemba, L. D.; Griffin, R. J.; Whitlow, S.; Talbot, R. W.

    2011-12-01

    Size distributions up to 10-micron aerosol diameter ( DP) of organic carbon (OC) and water-soluble organic carbon (WSOC) were measured at two sites in coastal New England, slightly inland at Thompson Farm (TF) and offshore at Isles of Shoals (IOS). Significant OC concentrations were measured across the full size distribution at TF and IOS, respectively. The WSOC fraction (WSOC/OC) was largest in the accumulation mode with values of 0.86 and 0.93 and smallest in the coarse mode with values of 0.61 and 0.79 at TF and IOS, respectively. Dicarboxylic acids containing up to five carbon atoms (C 5) were concentrated in droplet and accumulation mode aerosol with only minor contributions in the coarse mode. C 1-C 3 monocarboxylic acids were generally near or below detection limits. Results from proton nuclear magnetic resonance (H +-NMR) spectroscopy analyses showed that the organic functional group characterized by protons in the alpha position to an unsaturated carbon atoms ([H-C-C dbnd ]) was the dominant WSOC functionality at both TF and IOS, constituting 34 and 43% of carbon-weighted H +-NMR signal, respectively. Size distributions of each H +-NMR-resolved organic functionality are presented. Source apportionment using H +-NMR fingerprints is also presented, and results indicate that nearly all of the WSOC at TF and IOS spectroscopically resembled secondary organic aerosol, regardless of DP.

  17. Examining Urban Impervious Surface Distribution and Its Dynamic Change in Hangzhou Metropolis

    Directory of Open Access Journals (Sweden)

    Longwei Li

    2016-03-01

    Full Text Available Analysis of urban distribution and its expansion using remote sensing data has received increasing attention in the past three decades, but little research has examined spatial patterns of urban distribution and expansion with buffer zones in different directions. This research selected Hangzhou metropolis as a case study to analyze spatial patterns and dynamic changes based on time-series urban impervious surface area (ISA datasets. ISA was developed from Landsat imagery between 1991 and 2014 using a hybrid approach consisting of linear spectral mixture analysis, decision tree classifiers, and post-processing. The spatial patterns of ISA distribution and its dynamic changes in eight directions—east, southeast, south, southwest, west, northwest, north, and northeast—at the temporal scale were analyzed with a buffer zone-based approach. This research indicated that ISA can be extracted from Landsat imagery with both producer and user accuracies of over 90%. ISA in Hangzhou metropolis increased from 146 km2 in 1991 to 868 km2 in 2014. Annual ISA growth rates were between 15.6 km2 and 48.8 km2 with the lowest growth rate in 1994–2000 and the highest growth rate in 2005–2010. Urban ISA increase before 2000 was mainly due to infilling within the urban landscape, and, after 2005, due to urban expansion in the urban-rural interfaces. Urban expansion in this study area has different characteristics in various directions that are influenced by topographic factors and urban development policies.

  18. A spatially distributed model for assessment of the effects of changing land use and climate on urban stream quality: Development of a Spatially Distributed Urban Water Quality Model

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Ning [Department of Civil and Environmental Engineering, University of Washington, Seattle WA USA; Pacific Northwest National Laboratory, Richland WA USA; Yearsley, John [Department of Civil and Environmental Engineering, University of Washington, Seattle WA USA; Baptiste, Marisa [Department of Civil and Environmental Engineering, University of Washington, Seattle WA USA; Cao, Qian [Department of Geography, University of California Los Angeles, Los Angeles CA USA; Lettenmaier, Dennis P. [Department of Geography, University of California Los Angeles, Los Angeles CA USA; Nijssen, Bart [Department of Civil and Environmental Engineering, University of Washington, Seattle WA USA

    2016-08-22

    While the effects of land use change in urban areas have been widely examined, the combined effects of climate and land use change on the quality of urban and urbanizing streams have received much less attention. We describe a modeling framework that is applicable to the evaluation of potential changes in urban water quality and associated hydrologic changes in response to ongoing climate and landscape alteration. The grid-based spatially distributed model, DHSVM-WQ, is an outgrowth of the Distributed Hydrology-Soil-Vegetation Model (DHSVM) that incorporates modules for assessing hydrology and water quality in urbanized watersheds at a high spatial and temporal resolution. DHSVM-WQ simulates surface runoff quality and in-stream processes that control the transport of nonpoint-source (NPS) pollutants into urban streams. We configure DHSVM-WQ for three partially urbanized catchments in the Puget Sound region to evaluate the water quality responses to current conditions and projected changes in climate and/or land use over the next century. Here we focus on total suspended solids (TSS) and total phosphorus (TP) from nonpoint sources (runoff), as well as stream temperature. The projection of future land use is characterized by a combination of densification in existing urban or partially urban areas, and expansion of the urban footprint. The climate change scenarios consist of individual and concurrent changes in temperature and precipitation. Future precipitation is projected to increase in winter and decrease in summer, while future temperature is projected to increase throughout the year. Our results show that urbanization has a much greater effect than climate change on both the magnitude and seasonal variability of streamflow, TSS and TP loads largely due to substantially increased streamflow, and particularly winter flow peaks. Water temperature is more sensitive to climate warming scenarios than to urbanization and precipitation changes. Future urbanization and

  19. Aerosol Optical Properties in Southeast Asia From AERONET Observations

    Science.gov (United States)

    Eck, T. F.; Holben, B. N.; Boonjawat, J.; Le, H. V.; Schafer, J. S.; Reid, J. S.; Dubovik, O.; Smirnov, A.

    2003-12-01

    There is little published data available on measured optical properties of aerosols in the Southeast Asian region. The AERONET project and collaborators commenced monitoring of aerosol optical properties in February 2003 at four sites in Thailand and two sites in Viet Nam to measure the primarily anthropogenic aerosols generated by biomass burning and fossil fuel combustion/ industrial emissions. Automatic sun/sky radiometers at each site measured spectral aerosol optical depth in 7 wavelengths from 340 to 1020 nm and combined with directional radiances in the almucantar, retrievals were made of spectral single scattering albedo and aerosol size distributions. Angstrom exponents, size distributions and spectral single scattering albedo of primarily biomass burning aerosols at rural sites are compared to measurements made at AERONET sites in other major biomass burning regions in tropical southern Africa, South America, and in boreal forest regions. Additionally, the aerosol single scattering albedo and size distributions measured in Bangkok, Thailand are compared with those measured at other urban sites globally. The influences of aerosols originating from other regions outside of Southeast Asia are analyzed using trajectory analyses. Specifically, cases of aerosol transport and mixing from Southern China and from India are presented.

  20. Effect of urbanization on the winter precipitation distribution in Beijing area

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    According to the urbanization extent of Beijing area, and with 1980 as a turning point, the duration from 1961 to 2000 is divided into two periods: one is defined as the slow urbanization period from 1961 to 1980, and other one as the fast urbanization period from 1981 to 2000. Based on the 40-year’s precipi-tation data of 14 standard weather stations in Beijing area, the effect of urbanization on precipitation distribution is studied. It is found that there has been a noticeable and systematic change of winter precipitation distribution pattern between these two periods in Beijing area: in the slow urbanization period, the precipitation in the southern part of Beijing is more than that in the northern part; but in the fast urbanization period, the precipitation distribution pattern is reverse, i.e. the precipitation in the southern part is less than that in the northern part; But in other seasons, the precipitation distribution pattern did not change remarkably in general. The possible cause resulting in the change of winter precipitation distribution pattern, might be that with urban area extension, the effects of "urban heat island" and "urban dry island" become more and more intensified, and increase hydrometeors evapo-ration below precipitable cloud, and then cause less precipitation received on the ground surface in the downtown and the southern part. It is also noteworthy to further research why the precipitation distri-bution pattern does not change systematically in other seasons except winter after intense urbaniza-tion in Beijing area.

  1. Impact of aerosol particle sources on optical properties in urban, regional and remote areas in the north-western Mediterranean

    Science.gov (United States)

    Ealo, Marina; Alastuey, Andrés; Pérez, Noemí; Ripoll, Anna; Querol, Xavier; Pandolfi, Marco

    2018-01-01

    Further research is needed to reduce the existing uncertainties on the effect that specific aerosol particle sources have on light extinction and consequently on climate. This study presents a new approach that aims to quantify the mass scattering and absorption efficiencies (MSEs and MAEs) of different aerosol sources at urban (Barcelona - BCN), regional (Montseny - MSY) and remote (Montsec - MSA) background sites in the north-western (NW) Mediterranean. An analysis of source apportionment to the measured multi-wavelength light scattering (σsp) and absorption (σap) coefficients was performed by means of a multilinear regression (MLR) model for the periods 2009-2014, 2010-2014 and 2011-2014 at BCN, MSY and MSA respectively. The source contributions to PM10 mass concentration, identified by means of the positive matrix factorization (PMF) model, were used as dependent variables in the MLR model. With this approach we addressed both the effect that aerosol sources have on air quality and their potential effect on light extinction through the determination of their MSEs and MAEs. An advantage of the presented approach is that the calculated MSEs and MAEs take into account the internal mixing of atmospheric particles. Seven aerosol sources were identified at MSA and MSY, and eight sources at BCN. Mineral, aged marine, secondary sulfate, secondary nitrate and V-Ni bearing sources were common at the three sites. Traffic, industrial/metallurgy and road dust resuspension sources were isolated at BCN, whereas mixed industrial/traffic and aged organics sources were identified at MSY and MSA. The highest MSEs were observed for secondary sulfate (4.5 and 10.7 m2 g-1, at MSY and MSA), secondary nitrate (8.8 and 7.8 m2 g-1) and V-Ni bearing source (8 and 3.5 m2 g-1). These sources dominated the scattering throughout the year with marked seasonal trends. The V-Ni bearing source, originating mainly from shipping in the area under study, simultaneously contributed to both

  2. Source characterization of urban particles from meat smoking activities in Chongqing, China using single particle aerosol mass spectrometry.

    Science.gov (United States)

    Chen, Yang; Wenger, John C; Yang, Fumo; Cao, Junji; Huang, Rujin; Shi, Guangming; Zhang, Shumin; Tian, Mi; Wang, Huanbo

    2017-09-01

    A Single Particle Aerosol Mass Spectrometer (SPAMS) was deployed in the urban area of Chongqing to characterize the particles present during a severe particulate pollution event that occurred in winter 2014-2015. The measurements were made at a time when residents engaged in traditional outdoor meat smoking activities to preserve meat before the Chinese Spring Festival. The measurement period was predominantly characterized by stagnant weather conditions, highly elevated levels of PM 2.5 , and low visibility. Eleven major single particle types were identified, with over 92.5% of the particles attributed to biomass burning emissions. Most of the particle types showed appreciable signs of aging in the stagnant air conditions. To simulate the meat smoking activities, a series of controlled smoldering experiments was conducted using freshly cut pine and cypress branches, both with and without wood logs. SPAMS data obtained from these experiments revealed a number of biomass burning particle types, including an elemental and organic carbon (ECOC) type that proved to be the most suitable marker for meat smoking activities. The traditional activity of making preserved meat in southwestern China is shown here to be a major source of particulate pollution. Improved measures to reduce emissions from the smoking of meat should be introduced to improve air quality in regions where smoking meat activity prevails. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Spatial distribution of trace metals in sediments from urban streams of Semarang, Central Java, Indonesia.

    NARCIS (Netherlands)

    Widianarko, B.; Verweij, R.A.; van Gestel, C.A.M.; van Straalen, N.M.

    2000-01-01

    Elevated environmental concentrations of metals are usually associated with the impact of urbanization. The present study is focused on metal contamination in urban sediments. A field survey was carried out to determine the distribution of four metals, i.e., cadmium (Cd), lead (Pb), copper (Cu), and

  4. Characteristics of thin and coarse particulates of urban and natural brazilian aerosols

    International Nuclear Information System (INIS)

    Orsini, C.Q.; Tabacnics, M.H.; Artaxo, P.; Andrade, M.F.; Kerr, A.S.

    1994-01-01

    Thin and coarse particulate were sampled during the period 1982-1985 in a natural coastal forest (Jureia), and five urban-industrial regions (Vitoria, Salvador, Porto Alegre, Sao Paulo and Belo Horizonte). The time variation of the concentration in the air, and the relative elementary composition of the thin and coarse particulate, sampled by thin and Coarse Particulate Sampler (AFG), were determined by gravimetric method and PIXE analysis respectively. The results demonstrated that the ground dust and salt from the sea are unequivocally one of the largest sources of coarse particulate, and also the ground is a significant thin particulate source. 25 refs, 22 figs, 28 tabs. (L.C.J.A.)

  5. Source Apportionment of the Size-Fractionated Urban Aerosols in and around Kolkata, India

    Science.gov (United States)

    Sarkar, Ujjaini; Haque, Monirul; Roy, Rajdeep; Chakraborty, Sanjoy

    Our main objective was to estimate the heavy metals like the Lead, Mercury, Cadmium, Sodium, Potassium, Calcium, Aluminium, and Iron, in addition to ammonium, chloride, nitrate, and sulphate ions, by Atomic Absorption Spectrophotometry and Ion Chromatography and apportion the most probable sources using the Chemical Mass Balance Model. The three urban locations of Behala Chowrasta, Rabindra Sadan, and Shyam Bazaar Five Points were chosen within the city of Kolkata. One rural location was chosen at the Indian Institute of Technology campus, Kharagpur, a rural site in the Midnapur District of the state of West Bengal, India. The results look quite encouraging.

  6. Seasonal variation of spherical aerosols distribution in East Asia based on ground and space Lidar observation and a Chemical transport model

    Science.gov (United States)

    Hara, Y.; Yumimoto, K.; Uno, I.; Shimizu, A.; Sugimoto, N.; Ohara, T.

    2009-12-01

    The anthropogenic aerosols largely impact on not only human health but also global climate system, therefore air pollution in East Asia due to a rapid economic growth has been recognized as a significant environmental problem. Several international field campaigns had been conducted to elucidate pollutant gases, aerosols characteristics and radiative forcing in East Asia. (e.g., ACE-Asia, TRACE-P, ADEC, EAREX 2005). However, these experiments were mainly conducted in springtime, therefore seasonal variation of aerosols distribution has not been clarified well yet. National Institute for Environmental Studies (NIES) has been constructing a lidar networks by automated dual wavelength / polarization Mie-lidar systems to observe the atmospheric environment in Asian region since 2001. Furthermore, from June 2006, space-borne backscatter lidar, Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), onboard NASA/CALIPSO satellite, measures continuous global aerosol and cloud vertical distribution with very high spatial resolution. In this paper, we will show the seasonal variation of aerosols distribution in East Asia based on the NIES lidar network observation, Community Multi-scale Air Quality Modeling System (CMAQ) chemical transport model simulation and CALIOP observation over the period from July 2006 to December 2008. We found that CMAQ result explains the typical seasonal aerosol characteristics by lidar observations. For example, CMAQ and ground lidar showed a summertime peak of aerosol optical thickness (AOT) at Beijing, an autumn AOT peak at Guangzhou and summertime AOT trough at Hedo, Okinawa. These characteristics are mainly controlled by seasonal variations of Asian summer/winter monsoon system. We also examined the CMAQ seasonal average aerosol extinction profiles with ground lidar and CALIOP extinction data. These comparisons clarified that the CMAQ reproduced the observed aerosol layer depth well in the downwind region. Ground lidar and CALIOP seasonal

  7. Global distribution and evolvement of urbanization and PM2.5 (1998-2015)

    Science.gov (United States)

    Yang, Dongyang; Ye, Chao; Wang, Xiaomin; Lu, Debin; Xu, Jianhua; Yang, Haiqing

    2018-06-01

    PM2.5 concentrations increased and have been one of the major social issues along with rapid urbanization in many regions of the world in recent decades. The development of urbanization differed among regions, PM2.5 pollution also presented discrepant distribution across the world. Thus, this paper aimed to grasp the profile of global distribution of urbanization and PM2.5 and their evolutionary relationships. Based on global data for the proportion of the urban population and PM2.5 concentrations in 1998-2015, this paper investigated the spatial distribution, temporal variation, and evolutionary relationships of global urbanization and PM2.5. The results showed PM2.5 presented an increasing trend along with urbanization during the study period, but there was a variety of evolutionary relationships in different countries and regions. Most countries in East Asia, Southeast Asia, South Asia, and some African countries developed with the rapid increase in both urbanization and PM2.5. Under the impact of other socioeconomic factors, such as industry and economic growth, the development of urbanization increased PM2.5 concentrations in most Asian countries and some African countries, but decreased PM2.5 concentrations in most European and American countries. The findings of this study revealed the spatial distributions of global urbanization and PM2.5 pollution and provided an interpretation on the evolution of urbanization-PM2.5 relationships, which can contribute to urbanization policies making aimed at successful PM2.5 pollution control and abatement.

  8. Seasonal variation and source estimation of organic compounds in urban aerosol of Augsburg, Germany

    International Nuclear Information System (INIS)

    Pietrogrande, Maria Chiara; Abbaszade, Guelcin; Schnelle-Kreis, Juergen; Bacco, Dimitri; Mercuriali, Mattia; Zimmermann, Ralf

    2011-01-01

    This study reports a general assessment of the organic composition of the PM 2.5 samples collected in the city of Augsburg, Germany in a summer (August-September 2007) and a winter (February-March 2008) campaign of 36 and 30 days, respectively. The samples were directly submitted to in-situ derivatisation thermal desorption gas chromatography coupled with time of flight mass spectrometry (IDTD-GC-TOFMS) to simultaneously determine the concentrations of many classes of molecular markers, such as n-alkanes, iso- and anteiso-alkanes, polycyclic aromatic hydrocarbons (PAHs), oxidized PAHs, n-alkanoic acids, alcohols, saccharides and others. The PCA analysis of the data identified the contributions of three emission sources, i.e., combustion sources, including fossil fuel emissions and biomass burning, vegetative detritus, and oxidized PAHs. The PM chemical composition shows seasonal trend: winter is characterized by high contribution of petroleum/wood combustion while the vegetative component and atmospheric photochemical reactions are predominant in the hot season. - Highlights: → 59 molecular markers were simultaneously determined by thermal desorption GC-MS. → Organic composition of urban PM 2.5 in Augsburg, Germany, was characterized. → Fossil fuel, vegetative detritus, coal/wood burning are the main sources. → Seasonal trends winter vs. summer were identified. - Organic composition of the urban PM 2.5 identifies seasonal trend of the main sources: fossil fuel and biomass combustion sources, vegetative detritus, atmospheric photochemical reactions.

  9. Stratospheric aerosols

    International Nuclear Information System (INIS)

    Rosen, J.; Ivanov, V.A.

    1993-01-01

    Stratospheric aerosol measurements can provide both spatial and temporal data of sufficient resolution to be of use in climate models. Relatively recent results from a wide range of instrument techniques for measuring stratospheric aerosol parameters are described. Such techniques include impactor sampling, lidar system sensing, filter sampling, photoelectric particle counting, satellite extinction-sensing using the sun as a source, and optical depth probing, at sites mainly removed from tropospheric aerosol sources. Some of these techniques have also had correlative and intercomparison studies. The main methods for determining the vertical profiles of stratospheric aerosols are outlined: lidar extinction measurements from satellites; impactor measurements from balloons and aircraft; and photoelectric particle counter measurements from balloons, aircraft, and rockets. The conversion of the lidar backscatter to stratospheric aerosol mass loading is referred to. Absolute measurements of total solar extinction from satellite orbits can be used to extract the aerosol extinction, and several examples of vertical profiles of extinction obtained with the SAGE satellite are given. Stratospheric mass loading can be inferred from extinction using approximate linear relationships but under restrictive conditions. Impactor sampling is essentially the only method in which the physical nature of the stratospheric aerosol is observed visually. Vertical profiles of stratospheric aerosol number concentration using impactor data are presented. Typical profiles using a dual-size-range photoelectric dustsonde particle counter are given for volcanically disturbed and inactive periods. Some measurements of the global distribution of stratospheric aerosols are also presented. Volatility measurements are described, indicating that stratospheric aerosols are composed primarily of about 75% sulfuric acid and 25% water

  10. Enhancing non-refractory aerosol apportionment from an urban industrial site through receptor modelling of complete high time-resolution aerosol mass spectra

    Science.gov (United States)

    McGuire, M. L.; Chang, R. Y.-W.; Slowik, J. G.; Jeong, C.-H.; Healy, R. M.; Lu, G.; Mihele, C.; Abbatt, J. P. D.; Brook, J. R.; Evans, G. J.

    2014-02-01

    Receptor modelling was performed on quadrupole unit mass resolution aerosol mass spectrometer (Q-AMS) sub-micron particulate matter (PM) chemical speciation measurements from Windsor, Ontario, an industrial city situated across the Detroit River from Detroit, Michigan. Aerosol and trace gas measurements were collected on board Environment Canada's CRUISER mobile laboratory. Positive matrix factorization (PMF) was performed on the AMS full particle-phase mass spectrum (PMFFull MS) encompassing both organic and inorganic components. This approach was compared to the more common method of analysing only the organic mass spectra (PMFOrg MS). PMF of the full mass spectrum revealed that variability in the non-refractory sub-micron aerosol concentration and composition was best explained by six factors: an amine-containing factor (Amine); an ammonium sulphate and oxygenated organic aerosol containing factor (Sulphate-OA); an ammonium nitrate and oxygenated organic aerosol containing factor (Nitrate-OA); an ammonium chloride containing factor (Chloride); a hydrocarbon-like organic aerosol (HOA) factor; and a moderately oxygenated organic aerosol factor (OOA). PMF of the organic mass spectrum revealed three factors of similar composition to some of those revealed through PMFFull MS: Amine, HOA and OOA. Including both the inorganic and organic mass proved to be a beneficial approach to analysing the unit mass resolution AMS data for several reasons. First, it provided a method for potentially calculating more accurate sub-micron PM mass concentrations, particularly when unusual factors are present, in this case, an Amine factor. As this method does not rely on a priori knowledge of chemical species, it circumvents the need for any adjustments to the traditional AMS species fragmentation patterns to account for atypical species, and can thus lead to more complete factor profiles. It is expected that this method would be even more useful for HR-ToF-AMS data, due to the ability

  11. Distribution of trace gases and aerosols in the troposphere over West Siberia and Kara Sea

    Science.gov (United States)

    Belan, Boris D.; Arshinov, Mikhail Yu.; Paris, Jean-Daniel; Nédélec, Philippe; Ancellet, Gérard; Pelon, Jacques; Berchet, Antoine; Arzoumanian, Emmanuel; Belan, Sergey B.; Penner, Johannes E.; Balin, Yurii S.; Kokhanenko, Grigorii; Davydov, Denis K.; Ivlev, Georgii A.; Kozlov, Artem V.; Kozlov, Alexander S.; Chernov, Dmitrii G.; Fofonov, Alexader V.; Simonenkov, Denis V.; Tolmachev, Gennadii

    2015-04-01

    The Arctic is affected by climate change much stronger than other regions of the globe. Permafrost thawing can lead to additional methane release, which enhances the greenhouse effect and warming, as well as changes of Arctic tundra ecosystems. A great part of Siberian Arctic is still unexplored. Ground-based investigations are difficult to be carried out in this area due to it is an out-of-the-way place. So, in spite of the high cost, aircraft-based in-situ measurements can provide a good opportunity to fill up the gap in data on the atmospheric composition over this region. The ninth YAK-AEROSIB campaign was focused on the airborne survey of Arctic regions of West Siberia. It was performed in October 2014. During the campaign, the high-precision in-situ measurements of CO2, CH4, CO, O3, black carbon and aerososls, including aerosol lidar profiles, have been carried out in the Siberian troposphere from Novosibirsk to Kara Sea. Vertical distributions of the above atmospheric constituents will be presented. This work was supported by LIA YAK-AEROSIB, CNRS (France), the French Ministry of Foreign Affairs, CEA (France), the Branch of Geology, Geophysics and Mining Sciences of RAS (Program No. 5); State contracts of the Ministry of Education and Science of Russia No. 14.604.21.0100, (RFMTFIBBB210290) and No. 14.613.21.0013 (RFMEFI61314X0013); Interdisciplinary integration projects of the Siberian Branch of the Russian Academy of Science No. 35, No. 70 and No. 131; and Russian Foundation for Basic Research (grants No. 14-05-00526 and 14-05-00590).

  12. Using different assumptions of aerosol mixing state and chemical composition to predict CCN concentrations based on field measurements in urban Beijing

    Science.gov (United States)

    Ren, Jingye; Zhang, Fang; Wang, Yuying; Collins, Don; Fan, Xinxin; Jin, Xiaoai; Xu, Weiqi; Sun, Yele; Cribb, Maureen; Li, Zhanqing

    2018-05-01

    Understanding the impacts of aerosol chemical composition and mixing state on cloud condensation nuclei (CCN) activity in polluted areas is crucial for accurately predicting CCN number concentrations (NCCN). In this study, we predict NCCN under five assumed schemes of aerosol chemical composition and mixing state based on field measurements in Beijing during the winter of 2016. Our results show that the best closure is achieved with the assumption of size dependent chemical composition for which sulfate, nitrate, secondary organic aerosols, and aged black carbon are internally mixed with each other but externally mixed with primary organic aerosol and fresh black carbon (external-internal size-resolved, abbreviated as EI-SR scheme). The resulting ratios of predicted-to-measured NCCN (RCCN_p/m) were 0.90 - 0.98 under both clean and polluted conditions. Assumption of an internal mixture and bulk chemical composition (INT-BK scheme) shows good closure with RCCN_p/m of 1.0 -1.16 under clean conditions, implying that it is adequate for CCN prediction in continental clean regions. On polluted days, assuming the aerosol is internally mixed and has a chemical composition that is size dependent (INT-SR scheme) achieves better closure than the INT-BK scheme due to the heterogeneity and variation in particle composition at different sizes. The improved closure achieved using the EI-SR and INT-SR assumptions highlight the importance of measuring size-resolved chemical composition for CCN predictions in polluted regions. NCCN is significantly underestimated (with RCCN_p/m of 0.66 - 0.75) when using the schemes of external mixtures with bulk (EXT-BK scheme) or size-resolved composition (EXT-SR scheme), implying that primary particles experience rapid aging and physical mixing processes in urban Beijing. However, our results show that the aerosol mixing state plays a minor role in CCN prediction when the κorg exceeds 0.1.

  13. Seasonal variations in chromium concentration in urban atmospheric aerosol in the city of Radom

    Directory of Open Access Journals (Sweden)

    Molik Artur

    2018-01-01

    Full Text Available This paper presents seasonal variations in the occurrence of chromium in urban particulate matter (PM. Radom is an interesting area for this type of research due to its typical antiquated heating infrastructure. PM samples of two particulate fractions PM2.5 (particulates ≤ 2.5 µm and PM10 (particulates ≤ 10 µm were collected using a Copley cascade impactor Hi-Flow MOUDI Model 130. Chromium was determined in the samples using the GF-AAS technique. The concentration of chromium in PM2.5 was in the range of 0.38 to 3.2 ng/m3, whereas in PM10 it ranged from 0.43 to 4.1 ng/m3.

  14. Modeling the Hydrological Cycle in the Atmosphere of Mars: Influence of a Bimodal Size Distribution of Aerosol Nucleation Particles

    Science.gov (United States)

    Shaposhnikov, Dmitry S.; Rodin, Alexander V.; Medvedev, Alexander S.; Fedorova, Anna A.; Kuroda, Takeshi; Hartogh, Paul

    2018-02-01

    We present a new implementation of the hydrological cycle scheme into a general circulation model of the Martian atmosphere. The model includes a semi-Lagrangian transport scheme for water vapor and ice and accounts for microphysics of phase transitions between them. The hydrological scheme includes processes of saturation, nucleation, particle growth, sublimation, and sedimentation under the assumption of a variable size distribution. The scheme has been implemented into the Max Planck Institute Martian general circulation model and tested assuming monomodal and bimodal lognormal distributions of ice condensation nuclei. We present a comparison of the simulated annual variations, horizontal and vertical distributions of water vapor, and ice clouds with the available observations from instruments on board Mars orbiters. The accounting for bimodality of aerosol particle distribution improves the simulations of the annual hydrological cycle, including predicted ice clouds mass, opacity, number density, and particle radii. The increased number density and lower nucleation rates bring the simulated cloud opacities closer to observations. Simulations show a weak effect of the excess of small aerosol particles on the simulated water vapor distributions.

  15. Spatial distribution and temporal variation of chemical species in the bulk atmospheric aerosols collected at the Okinawa archipelago, Japan

    Science.gov (United States)

    Handa, D.; Somada, Y.; Ijyu, M.; Azechi, S.; Nakaema, F.; Arakaki, T.; Tanahara, A.

    2009-12-01

    The economic development and population growth in recent Asia have been increasing air pollution. A computer simulation study showed that air pollutants emitted from Asian continent could spread quickly within northern hemisphere. We initiated a study to elucidate the special distribution and chemical characterization of atmospheric aerosols around Okinawa archipelago, Japan. Okinawa Island is situated approximately 1500 km south of Tokyo, Japan, 2000 km southeast of Beijing, China, and 1000 km south of South Korea. Its location in Asia is well suited for studying long-range transport of air pollutants in East Asia because maritime air mass prevails during summer, while continental air mass dominates during fall, winter, and spring. The maritime air mass data can be seen as background and can be compared with continental air masses which have been affected by anthropogenic activities. We simultaneously collected bulk aerosol samples by using the same types of high volume air samplers at Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS, Okinawa Island), Kume Island (ca. 160 km south-west of CHAAMS) and Minami-daitou Island (ca. 320 km south-east of CHAAMS). We determined the concentrations of water-soluble anions, cations and dissolved organic carbon (DOC) using ion chromatography, atomic absorption spectrometry, and total organic carbon analyzer, respectively. We report and discuss spatial distribution and temporal variation of chemical species concentrations in bulk atmospheric aerosols collected during July, 2008 to July, 2009. We determine “background” concentration of chemical components in Okinawa archipelago. We then compare each chemical component among CHAAMS, Kume Island and Minami-daito Island to elucidate the influence of the long-range transport of chemical species from Asian continent.

  16. Spatial-temporal characteristics of haze and vertical distribution of aerosols over the Yangtze River Delta of China.

    Science.gov (United States)

    Cao, Yueqian; Zhang, Wu; Wang, Wenjing

    2018-04-01

    Variation of haze events occurred in the Yangtze River Delta (YRD) of China, the characteristics of meteorological elements and the vertical distribution of aerosols during haze episodes were analyzed by utilizing data of ground observation, radiosonde and CALIPSO. The results illustrate that the frequency of haze events between 1981 and 2010 peaked in winter but bottomed out in summer and decreased from north to south in the YRD region, reaching at the lowest point in "low frequency center" - Shanghai. When haze happened, the most seriously affected area was 2-4km above the ground and the concentrated range of total backscattering coefficient (TBC) that decreased with altitude was 0.8×10 -3 -2.5×10 -3 km -1 ·sr -1 . Particulate depolarization ratio (PDR) was less than 40% in a large part and 93% aerosols over the YRD area were regular particles, while the irregular ones concentrated on 2km above the surface and the irregularity rose up but the diversity diminished when altitude increased. Color ratio (CR) was lower than 1.2 mostly at all altitudes and distributed asymmetrically above the ground. Nearly 80% aerosols under 10km were fine particles (CR1.0) clustered at 2-4km. Large particles (CR>1.2) aggregated in lower troposphere massively yet relatively smaller ones gathered in middle and upper troposphere. In the YRD region, aerosols with more powerful capabilities were wider and less regular than the ones of Northwestern China. Copyright © 2017. Published by Elsevier B.V.

  17. Exposure to aerosol and gaseous pollutants in a room ventilated with mixing air distribution

    DEFF Research Database (Denmark)

    Bivolarova, Mariya Petrova; Ondráček, Jakub; Ždímal, Vladimír

    2016-01-01

    The present study investigates the aerosol and gas dispersal in a mechanically ventilated room and the personal exposure to these contaminants. The study was performed in a full-scale climate chamber. The room was air conditioned via mixing total volume ventilation system. The room occupancy was ...... of the thermal manikin were measured. The results showed higher exposure to the contaminants measured at the breathing zone than at the ambient air. The behaviour of the tracer gas and the aerosols was similar.......The present study investigates the aerosol and gas dispersal in a mechanically ventilated room and the personal exposure to these contaminants. The study was performed in a full-scale climate chamber. The room was air conditioned via mixing total volume ventilation system. The room occupancy...... was simulated by a sitting dressed thermal manikin with realistic body shape. During the experiments monodisperse aerosols of three sizes and nitrous oxide tracer gas were generated simultaneously from one location in the room. The aerosol and gas concentrations in the bulk room air and in the breathing zone...

  18. Seasonal variability of carbon in humic-like matter of ambient size-segregated water soluble organic aerosols from urban background environment

    Science.gov (United States)

    Frka, Sanja; Grgić, Irena; Turšič, Janja; Gini, Maria I.; Eleftheriadis, Konstantinos

    2018-01-01

    Long-term measurements of carbon in HUmic-LIke Substances (HULIS-C) of ambient size-segregated water soluble organic aerosols were performed using a ten-stage low-pressure Berner impactor from December 2014 to November 2015 at an urban background environment in Ljubljana, Slovenia. The mass size distribution patterns of measured species (PM - particulate matter, WSOC - water-soluble organic carbon and HULIS-C) for all seasons were generally tri-modal (primarily accumulation mode) but with significant seasonal variability. HULIS-C was found to have similar distributions as WSOC, with nearly the same mass median aerodynamic diameters (MMADs), except for winter when the HULIS-C size distribution was bimodal. In autumn and winter, the dominant accumulation mode with MMAD at ca. 0.65 μm contributed 83 and 97% to the total HULIS-C concentration, respectively. HULIS-C accounted for a large fraction of WSOC, averaging more than 50% in autumn and 40% in winter. Alternatively, during warmer periods the contributions of ultrafine (27% in summer) and coarse mode (27% in spring) were also substantial. Based on mass size distribution characteristics, HULIS-C was found to be of various sources. In colder seasons, wood burning was confirmed as the most important HULIS source; secondary formation in atmospheric liquid water also contributed significantly, as revealed by the MMADs of the accumulation mode shifting to larger sizes. The distinct difference between the spring and summer ratios of HULIS-C/WSOC in fine particles (ca. 50% in spring, but only 10% in summer) indicated different sources and chemical composition of WSOC in summer (e.g., SOA formation from biogenic volatile organic compounds (BVOCs) via photochemistry). The enlarged amount of HULIS-C in the ultrafine mode in summer suggests that the important contribution was most likely from new particle formation during higher emissions of BVOC due to the vicinity of a mixed deciduous forest; the higher contribution of

  19. Implications of the Khrgian-Mazin Distribution Function for Water Clouds and Distribution Consistencies With Aerosols and Rain

    Science.gov (United States)

    1991-12-06

    particle concentration of aerosols). Dk. Akad. Nauk. (Soy. Phys. Dokl.) 63. de Saussure . H.B. (1789) Mem. Acad. Turin 4:409-424. (Historic reference...atmospheric optics). de Saussure , H.B. (1789) Mem. Acad. Turin, 4:425-440. (Historic reference, atmospheric optics). de Saussure . H.B. (1791) Mem. de

  20. Size-distributions of n-alkanes, PAHs and hopanes and their sources in the urban, mountain and marine atmospheres over East Asia

    Directory of Open Access Journals (Sweden)

    Z. Wang

    2009-11-01

    Full Text Available Size-segregated (9 stages n-alkanes, polycyclic aromatic hydrocarbons (PAHs and hopanes in the urban (Baoji city in inland China, mountain (Mt. Tai in east coastal China and marine (Okinawa Island, Japan atmospheres over East Asia were studied using a GC/MS technique. Ambient concentrations of n-alkanes (1698±568 ng m−3 in winter and 487±145 ng m−3 in spring, PAHs (536±80 and 161±39 ng m−3, and hopanes (65±24 and 20±2.4 ng m−3 in the urban air are 1–2 orders of magnitude higher than those in the mountain aerosols and 2–3 orders of magnitude higher than those in the marine samples. Mass ratios of n-alkanes, PAHs and hopanes clearly demonstrate coal-burning emissions as their major source. Size distributions of fossil fuel derived n-alkane, PAHs and hopanes were found to be unimodal in most cases, peaking at 0.7–1.1 μm size. In contrast, plant wax derived n-alkanes presented a bimodal distribution with two peaks at the sizes of 0.7–1.1 μm and >4.7 μm in the summer mountain and spring marine samples. Among the three types of samples, geometric mean diameter (GMD of the organics in fine mode (<2.1 μm was found to be smallest (av. 0.63 μm in spring for the urban samples and largest (1.01 μm for the marine samples, whereas the GMD in coarse mode (≥2.1 μm was found to be smallest (3.48 μm for the marine aerosols and largest (4.04 μm for the urban aerosols. The fine mode GMDs of the urban and mountain samples were larger in winter than in spring and summer. Moreover, GMDs of 3- and 4-ring PAHs were larger than those of 5- and 6-ring PAHs in the three types of atmospheres. Such differences in GMDs can be interpreted by the repartitioning of organic compounds and the coagulation and hygroscopic growth of particles during a long-range transport from the inland continent to the marine area, as well as the difference in their sources among the three regions.

  1. Particle size distribution of the radon progeny and ambient aerosols in the Underground Tourist Route "Liczyrzepa" Mine in Kowary Adit

    Science.gov (United States)

    Wołoszczuk, Katarzyna; Skubacz, Krystian

    2018-01-01

    Central Laboratory for Radiological Protection, in cooperation with Central Mining Institute performed measurements of radon concentration in air, potential alpha energy concentration (PAEC), particle size distribution of the radon progeny and ambient aerosols in the Underground Tourist-Educational Route "Liczyrzepa" Mine in Kowary Adit. A research study was developed to investigate the appropriate dose conversion factors for short-lived radon progeny. The particle size distribution of radon progeny was determined using Radon Progeny Particle Size Spectrometer (RPPSS). The device allows to receive the distribution of PAEC in the particle size range from 0.6 nm to 2494 nm, based on their activity measured on 8 stages composed of impaction plates or diffusion screens. The measurements of the ambient airborne particle size distribution were performed in the range from a few nanometres to about 20 micrometres using Aerodynamic Particle Sizer (APS) spectrometer and the Scanning Mobility Particle Sizer Spectrometer (SMPS).

  2. Activity size distributions for long-lived radon decay products in aerosols collected in Barcelona (Spain)

    International Nuclear Information System (INIS)

    Camacho, A.; Valles, I.; Vargas, A.; Gonzalez-Perosanz, M.; Ortega, X.

    2009-01-01

    The activity median aerodynamic diameters (AMADs) of long-lived radon decay product ( 210 Pb, 210 Po) in aerosols collected in the Barcelona area (Northeast Spain) during the period from April 2006 to February 2008 are presented. The 210 Po mean AMAD was 420 nm, while the 210 Pb mean AMAD was 500 nm. The temporal evolution of 210 Pb and 210 Po AMADs shows maxima in autumn and winter and minima in spring and summer. 210 Pb AMAD are being used to estimate the mean-residence time of atmospheric aerosols.

  3. Climate Impacts of CALIPSO-Guided Corrections to Black Carbon Aerosol Vertical Distributions in a Global Climate Model

    International Nuclear Information System (INIS)

    Kovilakam, Mahesh; Mahajan, Salil; Saravanan, R.; Chang, Ping

    2017-01-01

    Here, we alleviate the bias in the tropospheric vertical distribution of black carbon aerosols (BC) in the Community Atmosphere Model (CAM4) using the Cloud-Aerosol and Infrared Pathfinder Satellite Observations (CALIPSO)-derived vertical profiles. A suite of sensitivity experiments are conducted with 1x, 5x, and 10x the present-day model estimated BC concentration climatology, with (corrected, CC) and without (uncorrected, UC) CALIPSO-corrected BC vertical distribution. The globally averaged top of the atmosphere radiative flux perturbation of CC experiments is ~8–50% smaller compared to uncorrected (UC) BC experiments largely due to an increase in low-level clouds. The global average surface temperature increases, the global average precipitation decreases, and the ITCZ moves northward with the increase in BC radiative forcing, irrespective of the vertical distribution of BC. Further, tropical expansion metrics for the poleward extent of the Northern Hemisphere Hadley cell (HC) indicate that simulated HC expansion is not sensitive to existing model biases in BC vertical distribution.

  4. The aerosol distribution in Europe derived with the Community Multiscale Air Quality (CMAQ model: comparison to near surface in situ and sunphotometer measurements

    Directory of Open Access Journals (Sweden)

    V. Matthias

    2008-09-01

    Full Text Available The aerosol distribution in Europe was simulated with the Community Multiscale Air Quality (CMAQ model system version 4.5 for the years 2000 and 2001. The results were compared with daily averages of PM10 measurements taken in the framework of EMEP and with aerosol optical depth (AOD values measured within AERONET. The modelled total aerosol mass is typically about 30–60% lower than the corresponding measurements. However a comparison of the chemical composition of the aerosol revealed a considerably better agreement between the modelled and the measured aerosol components for ammonium, nitrate and sulfate, which are on average only 15–20% underestimated. Sligthly worse agreement was determined for sea salt, that was only avaliable at two sites. The largest discrepancies result from the aerosol mass which was not chemically specified by the measurements. The agreement between measurements and model is better in winter than in summer. The modelled organic aerosol mass is higher in summer than in winter but it is significantly underestimated by the model. This could be one of the main reasons for the discrepancies between measurements and model results. The other is that primary coarse particles are underestimated in the emissions. The probability distribution function of the PM10 measurements follows a log-normal distribution at most sites. The model is only able to reproduce this distribution function at non-coastal low altitude stations. The AOD derived from the model results is 20–70% lower than the values observed within AERONET. This is mainly attributed to the missing aerosol mass in the model. The day-to-day variability of the AOD and the log-normal distribution functions are quite well reproduced by the model. The seasonality on the other hand is underestimated by the model results because better agreement is achieved in winter.

  5. Seasonal variability of carbonaceous aerosols in an urban background area in Southern Italy

    Science.gov (United States)

    Cesari, D.; Merico, E.; Dinoi, A.; Marinoni, A.; Bonasoni, P.; Contini, D.

    2018-02-01

    Organic (OC) and Elemental Carbon (EC) are important components of atmospheric aerosol particles, playing a key role in climate system and potentially affecting human health. There is a lack of data reported for Southern Italy and this work aims to fill this gap, focusing the attention on the long-term trends of OC and EC concentrations in PM2.5 and PM10, and on atmospheric processes and sources influencing seasonal variability. Measurements were taken at the Environmental-Climate Observatory of Lecce (SE Italy, 40°20‧8″N-18°07‧28″E, 37 m a.s.l.), regional station of the Global Atmosphere Watch program (GAW-WMO). Daily PM10 and PM2.5 samples were collected between July 2013 and July 2016. In addition, starting in December 2014, simultaneous equivalent Black Carbon (eBC) concentrations in PM10 were measured using a Multi Angle Absorption Photometer. A subset of 722 PM samples (361 for each size fraction) was analysed by using a thermo-optical method with a Sunset Laboratory OC/EC analyser, to determine elemental and organic carbon concentrations. The average PM10 and PM2.5 concentrations were 28.8 μg/m3 and 17.5 μg/m3. The average OC and EC concentrations in PM10 were 5.4 μg/m3 and 0.8 μg/m3, in PM2.5 these were 4.7 μg/m3 and 0.6 μg/m3. Carbonaceous content was larger during cold season with respect to warm season as well as secondary organic carbon (SOC) that was evaluated using the OC/EC minimum ratio method. SOC was mainly segregated in PM2.5 and represented 53% - 75% of the total OC. A subset of EC data was compared with eBC measurements, showing a good correlation (R2 = 0.80), however, eBC concentrations were higher than EC concentrations of an average factor of 1.95 (+/- 0.55 standard deviation). This could be explained by the presence of a contribution of Brown Carbon (BrC), for example from biomass burning, in eBC measurements. Weekly patterns showed a slight decrease of carbon content during weekends with respect to weekdays especially

  6. Deterioration and optimal rehabilitation modelling for urban water distribution systems

    NARCIS (Netherlands)

    Zhou, Y.

    2018-01-01

    Pipe failures in water distribution systems can have a serious impact and hence it’s important to maintain the condition and integrity of the distribution system. This book presents a whole-life cost optimisation model for the rehabilitation of water distribution systems. It combines a pipe breakage

  7. Photoacoustic Optical Properties at UV, VIS, and near IR Wavelengths for Laboratory Generated and Winter Time Ambient Urban Aerosols

    Science.gov (United States)

    Gyawali, M.; Arnott, W. P.; Zaveri, R. A.; Song, C.; Moosmuller, H.; Liu, L.; Mishchenko, M. I.; Chen, L.-W.A.; Green, M. C.; Watson, J. G.; hide

    2012-01-01

    We present the laboratory and ambient photoacoustic (PA) measurement of aerosol light absorption coefficients at ultraviolet wavelength (i.e., 355 nm) and compare with measurements at 405, 532, 870, and 1047 nm. Simultaneous measurements of aerosol light scattering coefficients were achieved by the integrating reciprocal nephelometer within the PA's acoustic resonator. Absorption and scattering measurements were carried out for various laboratory generated aerosols, including salt, incense, and kerosene soot to evaluate the instrument calibration and gain insight on the spectral dependence of aerosol light absorption and scattering. Ambient measurements were obtained in Reno, Nevada, between 18 December 2009 and 18 January 2010. The measurement period included days with and without strong ground level temperature inversions, corresponding to highly polluted (freshly emitted aerosols) and relatively clean (aged aerosols) conditions. Particulate matter (PM) concentrations were measured and analyzed with other tracers of traffic emissions. The temperature inversion episodes caused very high concentration of PM (sub 2.5) and PM( sub 10) (particulate matter with aerodynamic diameters less than 2.5 micrometers and 10 micrometers, respectively) and gaseous pollutants: carbon monoxide (CO), nitric oxide (NO), and nitrogen dioxide (NO2). The diurnal change of absorption and scattering coefficients during the polluted (inversion) days increased approximately by a factor of two for all wavelengths compared to the clean days. The spectral variation in aerosol absorption coefficients indicated a significant amount of absorbing aerosol from traffic emissions and residential wood burning. The analysis of single scattering albedo (SSA), Angstrom exponent of absorption (AEA), and Angstrom exponent of scattering (AES) for clean and polluted days provides evidences that the aerosol aging and coating process is suppressed by strong temperature inversion under cloudy conditions. In

  8. Global distribution and climate forcing of marine organic aerosol: 1. Model improvements and evaluation

    Directory of Open Access Journals (Sweden)

    N. Meskhidze

    2011-11-01

    Full Text Available Marine organic aerosol emissions have been implemented and evaluated within the National Center of Atmospheric Research (NCAR's Community Atmosphere Model (CAM5 with the Pacific Northwest National Laboratory's 7-mode Modal Aerosol Module (MAM-7. Emissions of marine primary organic aerosols (POA, phytoplankton-produced isoprene- and monoterpenes-derived secondary organic aerosols (SOA and methane sulfonate (MS are shown to affect surface concentrations of organic aerosols in remote marine regions. Global emissions of submicron marine POA is estimated to be 7.9 and 9.4 Tg yr−1, for the Gantt et al. (2011 and Vignati et al. (2010 emission parameterizations, respectively. Marine sources of SOA and particulate MS (containing both sulfur and carbon atoms contribute an additional 0.2 and 5.1 Tg yr−1, respectively. Widespread areas over productive waters of the Northern Atlantic, Northern Pacific, and the Southern Ocean show marine-source submicron organic aerosol surface concentrations of 100 ng m−3, with values up to 400 ng m−3 over biologically productive areas. Comparison of long-term surface observations of water insoluble organic matter (WIOM with POA concentrations from the two emission parameterizations shows that despite revealed discrepancies (often more than a factor of 2, both Gantt et al. (2011 and Vignati et al. (2010 formulations are able to capture the magnitude of marine organic aerosol concentrations, with the Gantt et al. (2011 parameterization attaining better seasonality. Model simulations show that the mixing state of the marine POA can impact the surface number concentration of cloud condensation nuclei (CCN. The largest increases (up to 20% in CCN (at a supersaturation (S of 0.2% number concentration are obtained over biologically productive ocean waters when marine organic aerosol is assumed to be externally mixed with sea-salt. Assuming

  9. Evaluating the impact of improvements to the FLAMBE smoke source model on forecasts of aerosol distribution from NAAPS

    Science.gov (United States)

    Hyer, E. J.; Reid, J. S.

    2006-12-01

    As more forecast models aim to include aerosol and chemical species, there is a need for source functions for biomass burning emissions that are accurate, robust, and operable in real-time. NAAPS is a global aerosol forecast model running every six hours and forecasting distributions of biomass burning, industrial sulfate, dust, and sea salt aerosols. This model is run operationally by the U.S. Navy as an aid to planning. The smoke emissions used as input to the model are calculated from the data collected by the FLAMBE system, driven by near-real-time active fire data from GOES WF_ABBA and MODIS Rapid Response. The smoke source function uses land cover data to predict properties of detected fires based on literature data from experimental burns. This scheme is very sensitive to the choice of land cover data sets. In areas of rapid land cover change, the use of static land cover data can produce artifactual changes in emissions unrelated to real changes in fire patterns. In South America, this change may be as large as 40% over five years. We demonstrate the impact of a modified land cover scheme on FLAMBE emissions and NAAPS forecasts, including a fire size algorithm developed using MODIS burned area data. We also describe the effects of corrections to emissions estimates for cloud and satellite coverage. We outline areas where existing data sources are incomplete and improvements are required to achieve accurate modeling of biomass burning emissions in real time.

  10. On the diurnal cycle of urban aerosols, black carbon and the occurrence of new particle formation events in springtime São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    J. Backman

    2012-12-01

    Full Text Available Large conurbations are a significant source of the anthropogenic pollution and demographic differences between cities that result in a different pollution burden. The metropolitan area of São Paulo (MASP, population 20 million accounts for one fifth of the Brazilian vehicular fleet. A feature of MASP is the amount of ethanol used by the vehicular fleet, known to exacerbate air quality. The study describes the diurnal behaviour of the submicron aerosol and relies on total particle number concentration, particle number size distribution, light scattering and light absorption measurements. Modelled planetary boundary layer (PBL depth and air mass movement data were used to aid the interpretation. During morning rush-hour, stagnant air and a shallow PBL height favour the accumulation of aerosol pollution. During clear-sky conditions, there was a wind shift towards the edge of the city indicating a heat island effect with implications on particulate pollution levels at the site. The median total particle number concentration for the submicron aerosol typically varied in the range 1.6 × 104–3.2 × 104 cm−3 frequently exceeding 4 × 104 cm−3 during the day. During weekdays, nucleation-mode particles are responsible for most of the particles by numbers. The highest concentrations of total particle number concentrations and black carbon (BC were observed on Fridays. Median diurnal values for light absorption and light scattering (at 637 nm wavelength varied in the range 12–33 Mm−1 and 21–64 Mm−1, respectively. The former one is equal to 1.8–5.0 μg m−3 of BC. The growth of the PBL, from the morning rush-hour until noon, is consistent with the diurnal cycle of BC mass concentrations. Weekday hourly median single-scattering albedo (ω0 varied in the range 0.59–0.76. Overall, this suggests a top of atmosphere (TOA warming effect. However

  11. An Improved Distribution Policy with a Maintenance Aspect for an Urban Logistic Problem

    Directory of Open Access Journals (Sweden)

    Nadia Ndhaief

    2017-07-01

    Full Text Available In this paper, we present an improved distribution plan supporting an urban distribution center (UDC to solve the last mile problem of urban freight. This is motivated by the need of UDCs to satisfy daily demand in time under a high service level in allocated urban areas. Moreover, these demands could not be satisfied in individual cases because the delivery rate can be less than daily demand and/or affected by random failure or maintenance actions of vehicles. The scope of our work is to focus on a UDC, which needs to satisfy demands in a finite horizon. To that end, we consider a distribution policy on two sequential plans, a distribution plan correlated to a maintenance plan using a subcontracting strategy with several potential urban distribution centers (UDCs and performing preventive maintenance to ensure deliveries for their allocated urban area. The choice of subcontractor will depend on distance, environmental and availability criteria. In doing so, we define a mathematical model for searching the best distribution and maintenance plans using a subcontracting strategy. Moreover, we consider delay for the next periods with an expensive penalty. Finally, we present a numerical example illustrating the benefits of our approach.

  12. Characteristics, sources and evolution of fine aerosol (PM1) at urban, coastal and forest background sites in Lithuania

    NARCIS (Netherlands)

    Masalaite, A.; Holzinger, R.; Remeikis, V.; Roeckmann, Thomas; Dusek, U.

    The chemical and isotopic composition of organic aerosol (OA) samples collected on PM1 filters was determined as a function of desorption temperature to investigate the main sources of organic carbon and the effects of photochemical processing on atmospheric aerosol. The filter samples were

  13. Aerosol particle size distribution in building and caves: impact to the radon-related dose evaluation

    International Nuclear Information System (INIS)

    Berka, Z.; Thinova, L.; Brandejsova, E.; Zdimal, V.; Fronka, A.; Milka, D.

    2004-01-01

    The results of evaluation of the aerosol particle size spectra observed in the Bozkov cave are presented and compared with the spectra observed in residential areas. The radon-to-dose conversion factor is discussed, as is the correction factor referred to as the cave factor. (P.A.)

  14. LIDAR Measurements of the Vertical Distribution of Aerosol Optical and Physical Properties over Central Asia

    Science.gov (United States)

    The vertical structure of aerosol optical and physical properties was measured by Lidar in Eastern Kyrgyzstan, Central Asia, from June 2008 to May 2009. Lidar measurements were supplemented with surface-based measurements of PM2.5 and PM10 mass and chemical ...

  15. Seasonal and spatial variability of the OM/OC mass ratios and high regional correlation between oxalic acid and zinc in Chinese urban organic aerosols

    Directory of Open Access Journals (Sweden)

    L. Xing

    2013-04-01

    Full Text Available We calculated the organic matter to organic carbon mass ratios (OM/OC mass ratios in PM2.5 collected from 14 Chinese cities during summer and winter of 2003 and analyzed the causes for their seasonal and spatial variability. The OM/OC mass ratios were calculated two ways. Using a mass balance method, the calculated OM/OC mass ratios averaged 1.92 ± 0.39 year-round, with no significant seasonal or spatial variation. The second calculation was based on chemical species analyses of the organic compounds extracted from the PM2.5 samples using dichloromethane/methanol and water. The calculated OM/OC mass ratio in summer was relatively high (1.75 ± 0.13 and spatially-invariant due to vigorous photochemistry and secondary organic aerosol (OA production throughout the country. The calculated OM/OC mass ratio in winter (1.59 ± 0.18 was significantly lower than that in summer, with lower values in northern cities (1.51 ± 0.07 than in southern cities (1.65 ± 0.15. This likely reflects the wider usage of coal for heating purposes in northern China in winter, in contrast to the larger contributions from biofuel and biomass burning in southern China in winter. On average, organic matter constituted 36% and 34% of Chinese urban PM2.5 mass in summer and winter, respectively. We report, for the first time, a high regional correlation between Zn and oxalic acid in Chinese urban aerosols in summer. This is consistent with the formation of stable Zn oxalate complex in the aerosol phase previously proposed by Furukawa and Takahashi (2011. We found that many other dicarboxylic acids were also highly correlated with Zn in the summer Chinese urban aerosol samples, suggesting that they may also form stable organic complexes with Zn. Such formation may have profound implications for the atmospheric abundance and hygroscopic properties of aerosol dicarboxylic acids.

  16. Seasonal and spatial variability of the OM/OC mass ratios and high regional correlation between oxalic acid and zinc in Chinese urban organic aerosols

    Science.gov (United States)

    Xing, L.; Fu, T.-M.; Cao, J. J.; Lee, S. C.; Wang, G. H.; Ho, K. F.; Cheng, M.-C.; You, C.-F.; Wang, T. J.

    2013-04-01

    We calculated the organic matter to organic carbon mass ratios (OM/OC mass ratios) in PM2.5 collected from 14 Chinese cities during summer and winter of 2003 and analyzed the causes for their seasonal and spatial variability. The OM/OC mass ratios were calculated two ways. Using a mass balance method, the calculated OM/OC mass ratios averaged 1.92 ± 0.39 year-round, with no significant seasonal or spatial variation. The second calculation was based on chemical species analyses of the organic compounds extracted from the PM2.5 samples using dichloromethane/methanol and water. The calculated OM/OC mass ratio in summer was relatively high (1.75 ± 0.13) and spatially-invariant due to vigorous photochemistry and secondary organic aerosol (OA) production throughout the country. The calculated OM/OC mass ratio in winter (1.59 ± 0.18) was significantly lower than that in summer, with lower values in northern cities (1.51 ± 0.07) than in southern cities (1.65 ± 0.15). This likely reflects the wider usage of coal for heating purposes in northern China in winter, in contrast to the larger contributions from biofuel and biomass burning in southern China in winter. On average, organic matter constituted 36% and 34% of Chinese urban PM2.5 mass in summer and winter, respectively. We report, for the first time, a high regional correlation between Zn and oxalic acid in Chinese urban aerosols in summer. This is consistent with the formation of stable Zn oxalate complex in the aerosol phase previously proposed by Furukawa and Takahashi (2011). We found that many other dicarboxylic acids were also highly correlated with Zn in the summer Chinese urban aerosol samples, suggesting that they may also form stable organic complexes with Zn. Such formation may have profound implications for the atmospheric abundance and hygroscopic properties of aerosol dicarboxylic acids.

  17. Estimation of Bimodal Urban Link Travel Time Distribution and Its Applications in Traffic Analysis

    Directory of Open Access Journals (Sweden)

    Yuxiong Ji

    2015-01-01

    Full Text Available Vehicles travelling on urban streets are heavily influenced by traffic signal controls, pedestrian crossings, and conflicting traffic from cross streets, which would result in bimodal travel time distributions, with one mode corresponding to travels without delays and the other travels with delays. A hierarchical Bayesian bimodal travel time model is proposed to capture the interrupted nature of urban traffic flows. The travel time distributions obtained from the proposed model are then considered to analyze traffic operations and estimate travel time distribution in real time. The advantage of the proposed bimodal model is demonstrated using empirical data, and the results are encouraging.

  18. Monitoring Pt and Rh in urban aerosols from Buenos Aires, Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Bocca, Beatrice; Caimi, Stefano; Caroli, Sergio [Istituto Superiore di Sanita, Viale Regina Elena 299, 00161, Rome (Italy); Smichowski, Patricia; Gomez, Dario [Comision Nacional de Energia Atomica, Unidad de Actividad Quimica, Centro Atomico Constituyentes, Av. Gral. Paz 1499, B1650KNA-San Martin, Pcia. de Buenos Aires (Argentina)

    2006-04-01

    Vehicular traffic is the main source of platinum group elements (PGEs) in highly populated urban areas like Buenos Aires where a traffic density of 1,500,000 vehicles day{sup -1} (corresponding to 7500 vehicles km{sup -2}) is estimated. Since there is no information on the levels of PGEs in Buenos Aires, a pilot study was undertaken to ascertain the amount of two major PGEs, namely Pt and Rh, in the atmosphere of this city. To this end, 49 samples of PM-10 particulate matter were collected during 7 days in seven representative sampling sites located downtown Buenos Aires and spread over an area of about 30 km{sup 2}. The collection of particulate matter was performed on ash-free glass-fiber filters using high volume samplers with PM-10 sampling heads. Filters loaded with the particulate matter were subjected to microwave (MW)-assisted acid digestion using a combination of HNO{sub 3}, HF and HClO{sub 4}. The resulting solutions were evaporated and then diluted with 0.1 mol l{sup -1} HCl. Analyses were performed by sector field inductively coupled plasma-mass spectrometry (SF-ICP-MS) and special attention was paid to the control of mass interferences. Statistical analysis was performed on the experimental data obtained for the element concentrations taking also into account local meteorological data for the monitored period. The highest concentrations of Pt and Rh were detected at two sites (Hospital Aleman and Casa Rapallini) located in streets with traffic consisting mostly of passenger cars. The Pt content (in pg m{sup -3}) in airborne particulate matter was found to vary from 2.3 to 47.7, with a mean value of 12.9+/-7, and that of Rh from 0.3 to 16.8, with a mean value of 3.9+/-2.8. These concentrations are by far below the levels for which adverse health effects might be expected to occur, i.e., around 100 ng m{sup -3}. On the other hand, monitoring of PGEs should be carried out in a systematic fashion to detect possible dramatic increases from today

  19. 2015 Plan. Project 6: urban and rural distribution systems

    International Nuclear Information System (INIS)

    1993-06-01

    The main development trends of distribution systems in 2015 Plan is studied, with the data of market continuity, costs and evolution of the physique system. Some factors that will influence the evolution of the distribution systems are presented and the impacts of economic view are discussed. The strategic lines that will give direction for the distribution expansion, including the energy conservation are also shown. (C.G.C.)

  20. Size distributions of aerosols in an indoor environment with engineered nanoparticle synthesis reactors operating under different scenarios

    International Nuclear Information System (INIS)

    Sahu, Manoranjan; Biswas, Pratim

    2010-01-01

    Size distributions of nanoparticles in the vicinity of synthesis reactors will provide guidelines for safe operation and protection of workers. Nanoparticle concentrations and size distributions were measured in a research academic laboratory environment with two different types of gas-phase synthesis reactors under a variety of operating conditions. The variation of total particle number concentration and size distribution at different distances from the reactor, off-design state of the fume hood, powder handling during recovery, and maintenance of reactors are established. Significant increases in number concentration were o