WorldWideScience

Sample records for aerosol size distribution

  1. 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

  2. Aerosol and air pollution size distribution

    Science.gov (United States)

    Shani, Gad; Haccoun, A.; Kushelevsky, A.

    The size distribution of aerosols was measured in a moderately industrial city, in a semi-arid zone on the Negev desert border. The aerosols in the city of Beer Sheva are from two sources: the dust coming from the desert and urban pollution. The size measurements were done with a cascade impactor. The elemental content of the aerosols was investigated by neutron activation analysis and X-ray fluorescence. The main elements of the dust are: Ca, Si, Fe, Na and the trace elements are: Sc, Se, La, Sm, Hf and others. The main elements of the urban pollution are S, Br, Pb, Cl, Hg and others. It was found that the elements belonging to each group can easily be classified by the size distribution. The analytical consideration of the aerosol size distribution of each group are discussed and two corresponding analytical expressions are suggested. It is shown that aerosols originating in the dust have a hump shape distribution around ~ 4μm, and those originating in urban pollution have a distribution decreasing with increasing aerosol diameter. Many examples are given to prove the conclusions.

  3. Indoor aerosol size distributions in a gymnasium.

    Science.gov (United States)

    Castro, Amaya; Calvo, Ana I; Alves, Célia; Alonso-Blanco, Elisabeth; Coz, Esther; Marques, Liliana; Nunes, Teresa; Fernández-Guisuraga, Jose Manuel; Fraile, Roberto

    2015-08-15

    In this study, an indoor/outdoor monitoring program was carried out in a gymnasium at the University of Leon, Spain. The main goal was a characterization of aerosol size distributions in a university gymnasium under different conditions and sports activities (with and without magnesia alba) and the study of the mass fraction deposited in each of the parts of the respiratory tract. The aerosol particles were measured in 31 discrete channels (size ranges) using a laser spectrometer probe. Aerosol size distributions were studied under different conditions: i) before sports activities, ii) activities without using magnesia alba, iii) activities using magnesia alba, iv) cleaning procedures, and v) outdoors. The aerosol refractive index and density indoors were estimated from the aerosol composition: 1.577-0.003i and 2.055 g cm(-3), respectively. Using the estimated density, the mass concentration was calculated, and the evolution of PM1, PM2.5 and PM10 for different activities was assessed. The quality of the air in the gymnasium was strongly influenced by the use of magnesia alba (MgCO3) and the number of gymnasts who were training. Due to the climbing chalk and the constant process of resuspension, average PM10 concentrations of over 440 μg m(-3) were reached. The maximum daily concentrations ranged from 500 to 900 μg m(-3). Particle size determines the place in the respiratory tract where the deposition occurs. For this reason, the inhalable, thoracic, tracheobronchial and respirable fractions were assessed for healthy adults and high risk people, according to international standards. The estimations show that, for healthy adults, up to 300 μg m(-3) can be retained by the trachea and bronchi, and 130 μg m(-3) may reach the alveolar region. The different physical activities and the attendance rates in the sports facility have a significant influence on the concentration and size distributions observed. PMID:25897726

  4. Comparison of aerosol size distribution in coastal and oceanic environments

    NARCIS (Netherlands)

    Kusmierczyk-Michulec, J.T.; Eijk, A.M.J. van

    2006-01-01

    The results of applying the empirical orthogonal functions (EOF) method to decomposition and approximation of aerosol size distributions are presented. A comparison was made for two aerosol data sets, representing coastal and oceanic environments. The first data set includes measurements collected a

  5. Elemental mass size distribution of the Debrecen urban aerosol

    International Nuclear Information System (INIS)

    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 2nd, 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 2nd 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

  6. Size distribution of natural radioactive aerosols in an underground building

    International Nuclear Information System (INIS)

    The size distribution of natural radioactive aerosols is a very important factor for evaluating the exposure dose contributed by radon. In order to measure the size distribution, a cascade impactor was employed for sampling in an underground building. The results of 4-time measurements at 58 places show that the sizes of natural radioactive aerosols are lognormal distribution, and the AMAD is between 0.087 and 0.427 μm with an average of 0.194 μm. The AMADs ranging from 0.1 to 0.3 μm cover 85% of all data. (authors)

  7. Comparison of aerosol size distribution in coastal and oceanic environments

    Science.gov (United States)

    Kusmierczyk-Michulec, Jolanta; van Eijk, Alexander M.

    2006-08-01

    The results of applying the empirical orthogonal functions (EOF) method to decomposition and approximation of aerosol size distributions are presented. A comparison was made for two aerosol data sets, representing coastal and oceanic environments. The first data set includes measurements collected at the Irish Atlantic coast in 1994 and 1995, the second one data collected during the Rough Evaporation Duct (RED) experiment that took place off Oahu, Hawaii in 2001. The main finding is that aerosol size distributions can be represented by a superposition of the mean size distribution and the first eigenvector multiplied by an amplitude function. For the two aerosol data sets the mean size distribution is very similar in the range of small particles sizes (radius 1μm). It is also reflected by the spectral shape of the eigenvector. The differences can be related to the type of aerosols present at both locations, and the amplitude function can be associated to meteorological conditions. The amplitude function also indicates the episodes with the maximum/minimum continental influence. The results of this analysis will be used in upgrades of the ANAM model.

  8. Comparison of aerosol size distribution in coastal and oceanic environments

    OpenAIRE

    Kusmierczyk-Michulec, J.T.; Eijk, A.M.J. van

    2006-01-01

    The results of applying the empirical orthogonal functions (EOF) method to decomposition and approximation of aerosol size distributions are presented. A comparison was made for two aerosol data sets, representing coastal and oceanic environments. The first data set includes measurements collected at the Irish Atlantic coast in 1994 and 1995, the second one data collected during the Rough Evaporation Duct (RED) experiment that took place off Oahu, Hawaii in 2001. The main finding is that aero...

  9. A New Method to Generate Micron-Sized AerosolS With Narrow Size Distribution

    Science.gov (United States)

    Gañón-Calvo, Alfonso; Barrero, Antonio

    1996-11-01

    Aerosols in the micron-size range with a remarkable monodisperse size distribution can be generated from the breaking up process of a capillary microjet. The size of the main droplets and satellites depend on the jet diameter, d_j, as well as the flow rate, Q, and liquid properties which eventually determine the jet`s breaking up. Therefore, the generation and control of capillary microjets is essential to produce sprays of small droplets with narrow size histograms. Electrosprays has been up to now one of the most successful techniques to produce monodisperse micron-size aerosols. As an alternative, we report here a new method, aerospray, to generate capillary micro jets which can compete against the electrospray for the production of aerosols of small droplets with very narrow size distribution. The method is outlined in the following. Liquid coming out from the exit of a capillary needle is sucked by means of a high speed gas stream (usually air) which flows throughout a hole separating two chambers at different pressures. Under certain parametric conditions of liquid properties, liquid and air flow rates, and geometric characteristics (needle and hole diameters, distance from the needle to the hole, etc), the liquid forms a steady capillary microjet of very small diameter which is speeded up an stabilized by the action of the viscous stresses at the gas liquid interface. The jet passes through the hole and goes out the outside chamber where eventually breaks up into microdroplets by varicose instabilities. Measurements from Laser-Doppler PDA Analizer of these aerosprays show that both the droplet size and its standard deviation are comparable to those obtained by electrospray techniques. On the other hand, using the aerospray, the standard deviation of the resulting droplet size distribution is of the order of those that can be obtained by ultrasonic atomization but the mean diameters can be more than one order of magnitude smaller.

  10. Activity Size Distributions of Natural Radioactive Aerosols in Outdoor Air

    International Nuclear Information System (INIS)

    Activity size distributions of short lived radon and thoron decay products, long lived radon decay product lead-210 and cosmogenic beryllium-7 in atmospheric aerosol particles were measured using a five-stage high volume cascade impactor. The activity concentrations were measured by gamma spectrometry. The significant difference between the activity median aerodynamic diameters of the short and long-lived radon progeny seems to indicate that, after generation, the primary activity size distribution change to greater particle diameters mainly caused by the coagulation with existing non-active aerosol particles during their residence time in the atmosphere. (author)

  11. 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

  12. 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 ostatní: 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

  13. Aerosol Particle Size Distributions at a Rural Coastal Site

    NARCIS (Netherlands)

    Leeuw, G. de; Vignati, E.

    1998-01-01

    Aerosol particle size distributions were measured on the Swedish island Ostergamsholm, about 3 km east of Gotland, from 26 April until 13 May, 1998. In this contribution preliminary results are presented of the dialysis of data collected at the south tip of the island at 10 m above sea level using a

  14. Aged boreal biomass burning aerosol size distributions from BORTAS 2011

    Science.gov (United States)

    Sakamoto, K. M.; Allan, J. D.; Coe, H.; Taylor, J. W.; Duck, T. J.; Pierce, J. R.

    2014-09-01

    Biomass-burning aerosols contribute to aerosol radiative forcing on the climate system. The magnitude of this effect is partially determined by aerosol size distributions, which are functions of source fire characteristics (e.g. fuel type, MCE) and in-plume microphysical processing. The uncertainties in biomass-burning emission number size-distributions in climate model inventories lead to uncertainties in the CCN concentrations and forcing estimates derived from these models. The BORTAS-B measurement campaign was designed to sample boreal biomass-burning outflow over Eastern Canada in the summer of 2011. Using these BORTAS-B data, we implement plume criteria to isolate the characteristic size-distribution of aged biomass-burning emissions (aged ∼1-2 days) from boreal wildfires in Northwestern Ontario. The composite median size-distribution yields a single dominant accumulation mode with Dpm = 230 nm (number-median diameter), σ = 1.7, which are comparable to literature values of other aged plumes of a similar type. The organic aerosol enhancement ratios (ΔOA / ΔCO) along the path of Flight b622 show values of 0.05-0.18 μg m-3 ppbv-1 with no significant trend with distance from the source. This lack of enhancement ratio increase/decrease with distance suggests no detectable net OA production/evaporation within the aged plume over the sampling period. A Lagrangian microphysical model was used to determine an estimate of the freshly emitted size distribution corresponding to the BORTAS-B aged size-distributions. The model was restricted to coagulation and dilution processes based on the insignificant net OA production/evaporation derived from the ΔOA / ΔCO enhancement ratios. We estimate that the fresh-plume median diameter was in the range of 59-94 nm with modal widths in the range of 1.7-2.8 (the ranges are due to uncertainty in the entrainment rate). Thus, the size of the freshly emitted particles is relatively unconstrained due to the uncertainties in the

  15. Aerosol size distribution seasonal characteristics measured in Tiksi, Russian Arctic

    Science.gov (United States)

    Asmi, E.; Kondratyev, V.; Brus, D.; Laurila, T.; Lihavainen, H.; Backman, J.; Vakkari, V.; Aurela, M.; Hatakka, J.; Viisanen, Y.; Uttal, T.; Ivakhov, V.; Makshtas, A.

    2016-02-01

    Four years of continuous aerosol number size distribution measurements from the Arctic Climate Observatory in Tiksi, Russia, are analyzed. Tiksi is located in a region where in situ information on aerosol particle properties has not been previously available. Particle size distributions were measured with a differential mobility particle sizer (in the diameter range of 7-500 nm) and with an aerodynamic particle sizer (in the diameter range of 0.5-10 μm). Source region effects on particle modal features and number, and mass concentrations are presented for different seasons. The monthly median total aerosol number concentration in Tiksi ranges from 184 cm-3 in November to 724 cm-3 in July, with a local maximum in March of 481 cm-3. The total mass concentration has a distinct maximum in February-March of 1.72-2.38 μg m-3 and two minimums in June (0.42 μg m-3) and in September-October (0.36-0.57 μg m-3). These seasonal cycles in number and mass concentrations are related to isolated processes and phenomena such as Arctic haze in early spring, which increases accumulation and coarse-mode numbers, and secondary particle formation in spring and summer, which affects the nucleation and Aitken mode particle concentrations. Secondary particle formation was frequently observed in Tiksi and was shown to be slightly more common in marine, in comparison to continental, air flows. Particle formation rates were the highest in spring, while the particle growth rates peaked in summer. These results suggest two different origins for secondary particles, anthropogenic pollution being the important source in spring and biogenic emissions being significant in summer. The impact of temperature-dependent natural emissions on aerosol and cloud condensation nuclei numbers was significant: the increase in both the particle mass and the CCN (cloud condensation nuclei) number with temperature was found to be higher than in any previous study done over the boreal forest region. In addition

  16. Mass size distributions of elemental aerosols in industrial area.

    Science.gov (United States)

    Moustafa, Mona; Mohamed, Amer; Ahmed, Abdel-Rahman; Nazmy, Hyam

    2015-11-01

    Outdoor aerosol particles were characterized in industrial area of Samalut city (El-minia/Egypt) using low pressure Berner cascade impactor as an aerosol sampler. The impactor operates at 1.7 m(3)/h flow rate. Seven elements were investigated including Ca, Ba, Fe, K, Cu, Mn and Pb using atomic absorption technique. The mean mass concentrations of the elements ranged from 0.42 ng/m(3) (for Ba) to 89.62 ng/m(3) (for Fe). The mass size distributions of the investigated elements were bi-modal log normal distribution corresponding to the accumulation and coarse modes. The enrichment factors of elements indicate that Ca, Ba, Fe, K, Cu and Mn are mainly emitted into the atmosphere from soil sources while Pb is mostly due to anthropogenic sources. PMID:26644919

  17. Aerosol Optical Properties and Determination of Aerosol Size Distribution in Wuhan, China

    Directory of Open Access Journals (Sweden)

    Wei Gong

    2014-01-01

    Full Text Available Columnar aerosol volume size distributions from March 2012 to February 2013 in Wuhan, China, were investigated with a focus on monthly and seasonal variations in the aerosol optical depths (AODs and Ångström exponents. AOD is wavelength dependent, and for AOD at, for example, 500 nm, the seasonal averaged AOD value decreased in the order of winter (~0.84, spring (~0.83, summer (~0.76 and autumn (~0.55. The Ångström exponent suggested that the aerosol sizes in summer (~1.22, winter (~1.14, autumn (~1.06 and spring (~0.99 varied from fine to coarse particles. The Ångström exponent and AOD could provide a qualitative evaluation of ASD. Moreover, aerosol size distribution (ASD was larger in winter than the other three seasons, especially from 1.0 µm to 15 µm due to heavy anthropogenic aerosol and damp climate. The ASD spectral shape showed a bimodal distribution in autumn, winter, and spring, with one peak (<0.1 in the fine mode range and the other (>0.14 in the coarse mode range. However, there appeared to be a trimodal distribution during summer, with two peaks in the coarse mode, which might be due to the hygroscopic growth of the local particles and the generation of aerosol precursor resulting from the extreme-high temperature and relative humidity.

  18. Retrieval of particle size distribution from aerosol optical thickness using an improved particle swarm optimization algorithm

    Science.gov (United States)

    Mao, Jiandong; Li, Jinxuan

    2015-10-01

    Particle size distribution is essential for describing direct and indirect radiation of aerosols. Because the relationship between the aerosol size distribution and optical thickness (AOT) is an ill-posed Fredholm integral equation of the first type, the traditional techniques for determining such size distributions, such as the Phillips-Twomey regularization method, are often ambiguous. Here, we use an approach based on an improved particle swarm optimization algorithm (IPSO) to retrieve aerosol size distribution. Using AOT data measured by a CE318 sun photometer in Yinchuan, we compared the aerosol size distributions retrieved using a simple genetic algorithm, a basic particle swarm optimization algorithm and the IPSO. Aerosol size distributions for different weather conditions were analyzed, including sunny, dusty and hazy conditions. Our results show that the IPSO-based inversion method retrieved aerosol size distributions under all weather conditions, showing great potential for similar size distribution inversions.

  19. Interpretation of aerosol trace metal particle size distributions

    International Nuclear Information System (INIS)

    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

  20. Performance of DMPS/C System in Determining Aerosol Particle Size Distribution

    International Nuclear Information System (INIS)

    An evaluation of performance of DMPS/C system TSI-3932 in determining aerosol particle size has been carried out. The evaluation consist of validity of experimentally transfer function, instrument resolution, and test of measurement accuracy and precision for monodisperse and polydisperse aerosol size distribution. Evaluation of measurement accuracy gave a deviation of 0.74 %, and evaluation of measurement precision gave variation coefficient of 0,50 % and 1.63 % for monodisperse aerosol and polydisperse aerosol respectively

  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)

    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.

  2. Research on measurement method of 220Rn progeny aerosol size distribution

    International Nuclear Information System (INIS)

    The method for measuring 220Rn progeny aerosol activity particle size distributions was introduced through ELPI system, α spectroscopy and the energy discrimination method. The different particle sizes of the 220Rn progeny aerosols were collected and the activity size distributions in the 220Rn laboratory of the University of South China were measured by this method. The experiment results show that the activity median aerodynamic diameter (AMAD) of ThB aerosol is 237 nm, and that of ThC is 245 nm. The simple and quick method can be used to monitor the particle size distributions of 220Rn progeny aerosol in real time, the aerosol activity size distributions of ThB and ThC can be obtained by this method at the same time, and the measurement accuracy of the energy spectrum is higher than that of custom method. (authors)

  3. Size distributions of the ambient and radon daughter aerosols in southern England and implications for dose

    International Nuclear Information System (INIS)

    The size distribution of ambient aerosols indoors and outside have been measured at several urban, suburban and rural locations in southern England, using an eleven stage, wire screen diffusion battery. At four indoor locations with relatively high radon daughter concentrations, the size distributions of the radon daughter aerosol were also measured, using the diffusion battery in conjunction with Cr-39 etched track detectors of alpha-activity. The transformation from size distribution of the ambient aerosol to the radon daughter activity-size distribution was examined, using various models of radon daughter attachment rates. The implications of the radon daughter aerosol size distributions estimated for the different indoor and outdoor locations are discussed in terms of variation in the conversion between exposure and effective dose equivalent

  4. Aerosol mobility size spectrometer

    Science.gov (United States)

    Wang, Jian; Kulkarni, Pramod

    2007-11-20

    A device for measuring aerosol size distribution within a sample containing aerosol particles. The device generally includes a spectrometer housing defining an interior chamber and a camera for recording aerosol size streams exiting the chamber. The housing includes an inlet for introducing a flow medium into the chamber in a flow direction, an aerosol injection port adjacent the inlet for introducing a charged aerosol sample into the chamber, a separation section for applying an electric field to the aerosol sample across the flow direction and an outlet opposite the inlet. In the separation section, the aerosol sample becomes entrained in the flow medium and the aerosol particles within the aerosol sample are separated by size into a plurality of aerosol flow streams under the influence of the electric field. The camera is disposed adjacent the housing outlet for optically detecting a relative position of at least one aerosol flow stream exiting the outlet and for optically detecting the number of aerosol particles within the at least one aerosol flow stream.

  5. Vertical profile and aerosol size distribution measurements in Iceland (LOAC)

    Science.gov (United States)

    Dagsson Waldhauserova, Pavla; Olafsson, Haraldur; Arnalds, Olafur; Renard, Jean-Baptiste; Vignelles, Damien; Verdier, Nicolas

    2014-05-01

    Cold climate and high latitudes regions contain important dust sources where dust is frequently emitted, foremost from glacially-derived sediments of riverbeds or ice-proximal areas (Arnalds, 2010; Bullard, 2013). Iceland is probably the most active dust source in the arctic/sub-arctic region (Dagsson-Waldhauserova, 2013). The frequency of days with suspended dust exceeds 34 dust days annually. Icelandic dust is of volcanic origin; it is very dark in colour and contains sharp-tipped shards with bubbles. Such properties allow even large particles to be easily transported long distances. Thus, there is a need to better understand the spatial and temporal variability of these dusts. Two launch campaigns of the Light Optical Aerosols Counter (LOAC) were conducted in Iceland with meteorological balloons. LOAC use a new optical design that allows to retrieve the size concentrations in 19 size classes between 0.2 and 100 microm, and to provide an estimate of the main nature of aerosols. Vertical stratification and aerosol composition of the subarctic atmosphere was studied in detail. The July 2011 launch represented clean non-dusty season with low winds while the November 2013 launch was conducted during the high winds after dusty period. For the winter flight (performed from Reykjavik), the nature of aerosols strongly changed with altitude. In particular, a thin layer of volcanic dust was observed at an altitude of 1 km. Further LOAC measurements are needed to understand the implication of Icelandic dust to the Arctic warming and climate change. A new campaign of LAOC launches is planned for May 2014. Reference: Arnalds, O., 2010. Dust sources and deposition of aeolian materials in Iceland. Icelandic Agricultural Sciences 23, 3-21. Bullard, J.E., 2013. Contemporary glacigenic inputs to the dust cycle. Earth Surface Processes and Landforms 38, 71-89. Dagsson-Waldhauserova, P., Arnalds O., Olafsson H. 2013. Long-term frequency and characteristics of dust storm events in

  6. 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.

  7. Aerosol mobility imaging for rapid size distribution measurements

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian; Hering, Susanne Vera; Spielman, Steven Russel; Kuang, Chongai

    2016-07-19

    A parallel plate dimensional electrical mobility separator and laminar flow water condensation provide rapid, mobility-based particle sizing at concentrations typical of the remote atmosphere. Particles are separated spatially within the electrical mobility separator, enlarged through water condensation, and imaged onto a CCD array. The mobility separation distributes particles in accordance with their size. The condensation enlarges size-separated particles by water condensation while they are still within the gap of the mobility drift tube. Once enlarged the particles are illuminated by a laser. At a pre-selected frequency, typically 10 Hz, the position of all of the individual particles illuminated by the laser are captured by CCD camera. This instantly records the particle number concentration at each position. Because the position is directly related to the particle size (or mobility), the particle size spectra is derived from the images recorded by the CCD.

  8. Measurements of Aerosol Charge and Size Distribution for Graphite, Gold, Palladium, and Silver Nanoparticles

    International Nuclear Information System (INIS)

    The role of charge on aerosol evolution and hence the nuclear source term has been an issue of interest, and there is a need for both experimental techniques and modeling for quantifying this role. Our focus here is on further exploration of a tandem differential mobility analyzer (TDMA) technique to simultaneously measure both the size and charge (positive, negative and neutral) dependent aerosol distributions. We have generated graphite, gold, silver, and palladium nanoparticles (aerosol) using a spark generator. We measure the electrical mobility-size distributions for these aerosols using a TDMA, and from these data we deduce the full charge-size distributions. We observe asymmetry in the particle size distributions for negative and positive charges. This asymmetry could have a bearing on the dynamics of charged aerosols, indicating that the assumption of symmetry for size distributions of negatively and positively charged particles in source term simulations may not be always appropriate. Also, the experimental technique should find applications in measurements of aerosol rate processes that are affected by both particle charge and size (e.g. coagulation, deposition, resuspension), and hence in modeling and simulation of the nuclear source term.

  9. Size distribution and element composition of dust aerosol in Chinese Otindag Sandland

    Institute of Scientific and Technical Information of China (English)

    CHENG Tiantao; L(U) Daren; CHEN Hongbin; WANG Gengchen

    2005-01-01

    Part physical and chemical characteristics of dust aerosol were determined for samples collected from Otindag Sandland of China in spring, 2001. Number concentration, mass concentration, chemical element concentration and size distribution of aerosol particles with 0.5 -m < Dp < 100.0 -m were examined. The average number and mass concentrations of aerosols were 274.8 cm-3 and 0.54 mg/m3 for the field period respectively, and 31.4 cm-3 and 0.07 mg/m3 for the non-dusty days. PM10 played a dominant role in the aerosol mass concentrations. The particles with Dp < 8.0 -m accounted for about 93.7% of total aerosol number loading in dusty days. The particle size distributions of aerosols were characterized by bi-modal logarithm normal function in heavy and moderate dusty days, and mono-modal in windblown and non-dusty days. Crustal elements such as Al, Fe, etc. in aerosols almost originated from soils. Pollutant elements of S, Pb, etc. associated with aerosols were affected by remote anthropogenic pollutant sources in upwind regions. Mo, V and Co in aerosols were possibly from other dust sources other than local soils. The aerosols over Otindag Sandland consisted of particles from local soils, upwind pollutant sources and other dust sources.

  10. Does the size distribution of mineral dust aerosols depend on the wind speed at emission?

    CERN Document Server

    Kok, Jasper F

    2011-01-01

    The size distribution of mineral dust aerosols partially determines their interactions with clouds, radiation, ecosystems, and other components of the Earth system. Several theoretical models predict that the dust size distribution depends on the wind speed at emission, with larger wind speeds predicted to produce smaller aerosols. The present study investigates this prediction using a compilation of published measurements of the size-resolved vertical dust flux emitted by eroding soils. Surprisingly, these measurements indicate that the size distribution of naturally emitted dust aerosols is independent of the wind speed. The recently formulated brittle fragmentation theory of dust emission is consistent with this finding, whereas other theoretical dust emission models are not. The independence of the emitted dust size distribution with wind speed simplifies both the interpretation of geological records of dust deposition and the parameterization of dust emission in atmospheric circulation models.

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

  13. Fog-influenced Submicron Aerosol Number Size Distributions

    Czech Academy of Sciences Publication Activity Database

    Zíková, Naděžda; Ždímal, Vladimír

    - : -, 2013, A44D-04. ISBN N. [AGU Fall Meeting 2013. San Francisco (US), 09.12.2013-13.12.2013] Grant ostatní: GA UK(CZ) 62213 Institutional support: RVO:67985858 Keywords : clouds and aerosols * aerosols and particles Subject RIV: CF - Physical ; Theoretical Chemistry

  14. Radioactivity size distributions of ambient aerosols in Helsinki, Finland during May 1986 after Chernobyl accident

    International Nuclear Information System (INIS)

    Ambient aerosol size distributions oof 131I, 103Ru, 132Te and 137Cs radionuclides were measured in Helsinki, Finland during May 7 - 14, 1986. Radioactivity size distributions were unimodal. Geometric mean diameter of 131I was in the size range 0.33 - 0.57 μm a.e.d.. Other isotopes had geometric mean diameters in the size range 0.65 - 0.93 μm a.e.d.. (author)

  15. Air Mass Back Trajectories and Dry Atmospheric Aerosol Mass Size Distributions in Prague

    Czech Academy of Sciences Publication Activity Database

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

    Prague: Czech Aerosol Society, 2013, A228. ISBN N. [European Aerosol Conference (EAC 2013). Prague (CZ), 01.09.2013-06.09.2013] R&D Projects: GA ČR GAP209/11/1342 Institutional support: RVO:67985858 Keywords : mass size distribution * air mass back trajectories * water soluble ions Subject RIV: CF - Physical ; Theoretical Chemistry http://eac2013.cz/index.php

  16. Simplifying aerosol size distributions modes simultaneously detected at four monitoring sites during SAPUSS

    OpenAIRE

    M. Brines; Dall'Osto, M.; Beddows, D.C.S.; R. M. Harrison; X. Querol

    2014-01-01

    The analysis of aerosol size distributions is a useful tool for understanding the sources and the processes influencing particle number concentrations (N) in urban areas. Hence, during the one-month SAPUSS campaign (Solving Aerosol Problems by Using Synergistic Strategies, EU Marie Curie Action) in autumn 2010 in Barcelona (Spain), four SMPSs (Scanning Mobility Particle Sizer) were simultaneously deployed at four monitoring sites: a road side (RSsite), an urban background si...

  17. Simplifying aerosol size distributions modes simultaneously detected at four monitoring sites during SAPUSS

    OpenAIRE

    M. Brines; Dall'Osto, M.; Beddows, D.C.S.; R. M. Harrison; X. Querol

    2013-01-01

    The analysis of aerosol size distributions is a useful tool for understanding the sources and the processes influencing particle number concentrations (N) in urban areas. Hence, during the one month SAPUSS campaign (Solving Aerosol Problems by Using Synergistic Strategies, EU Marie Curie Action) in autumn 2010 in Barcelona (Spain), four SMPS (Scanning Mobility Particle Sizers) were simultaneously deployed at four monitoring sites: a road side (RSsite), an urban background site located ...

  18. NUMBER CONCENTRATION, SIZE DISTRIBUTION AND FINE PARTICLE FRACTION OF TROPOSPHERIC AND STRATOSPHERIC AEROSOLS

    Institute of Scientific and Technical Information of China (English)

    Li Xu; Guangyu Shi; Li Zhang; Jun Zhou; Yasunobu Iwasaka

    2003-01-01

    Aerosol observations were carried out at Xianghe Scientific Balloon Base (39.45°N, 117°E) using a stratospheric balloon. The particle number concentrations of the tropospheric and stratospheric aerosols were directly explored.The vertical distributions of the number concentration, number-size (that is, particle number versus particle size)distribution, and the fraction of fine particles (0.5 μm>r>0.15 μm/r>0.15 μm) are reported in this paper. The profiles of particle concentration present multi-peak phenomenon. The pattern of size distribution for atmospheric aerosol indicates a tri-modal (r=~0.2 μm, ~0.88 μm and ~7.0 μm) and a bi-modal (r=~0.13 μm and 2.0 μm). The number-size distribution almost fits the Junge distribution for particles with r<0.5 μm in the stratosphere of 1993 and the troposphere of 1994. But the distributions of coarse particles (r>0.5 μm) are not uniform. The number-size distribution exhibits also a wide size range in the troposphere of 1993. The results demonstrate that fine particles represent the major portion in the troposphere during the measurement period, reaching as high as 95% in 1994. Certain coarse particle peaks in the troposphere were attributed to clouds and other causes, and in the stratosphere to volcanic eruption. The stratospheric aerosol layer consists of unique fractions of fine or coarse particles depending on their sources. In summary, the process of gas-to-particles conversion was active and the coarse particles were rich over the Xianghe area. The measurements also demonstrate that the spatial and temporal atmospheric aerosol distributions are nonuniform and changeful.

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

    International Nuclear Information System (INIS)

    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)

  20. Tropospheric aerosol size distributions simulated by three online global aerosol models using the M7 microphysics module

    Science.gov (United States)

    Zhang, K.; Wan, H.; Wang, B.; Zhang, M.; Feichter, J.; Liu, X.

    2010-03-01

    Tropospheric aerosol size distributions are simulated by three online global models that employ exactly the same modal approach but differ in many aspects such as model meteorology, natural aerosol emissions, sulfur chemistry, and the parameterization of deposition processes. The main purpose of this study is to identify where the largest inter-model discrepancies occur and what the main reasons are. The number concentrations of different aerosol size ranges are compared among the three models and against observations. Overall all the three models can capture the basic features of the observed aerosol number spatial distributions. The magnitude of the number concentration of each mode is consistent among the three models. Quantitative differences are also clearly detectable. For the soluble and insoluble coarse mode and accumulation mode, inter-model discrepancies mainly result from differences in the sea salt and dust emissions, as well as the different strengths of the convective transport in the meteorological models. For the nucleation mode and the soluble Aitken mode, the spread of the model results is largest in the tropics and in the middle and upper troposphere. Diagnostics and sensitivity experiments suggest that this large spread is closely related to the sulfur cycle in the models, which is strongly affected by the choice of sulfur chemistry scheme, its coupling with the convective transport and wet deposition calculation, and the related meteorological fields such as cloud cover, cloud water content, and precipitation. The aerosol size distributions simulated by the three models are compared to observations in the boundary layer. The characteristic shape and magnitude of the distribution functions are reasonably reproduced in typical conditions (i.e., clean, polluted and transition areas). Biases in the mode parameters over the remote oceans and the China adjacent seas are probably caused by the fixed mode variance in the mathematical formulations used

  1. Calibration of the passive cavity aerosol spectrometer probe for airborne determination of the size distribution

    Directory of Open Access Journals (Sweden)

    Y. Cai

    2013-09-01

    Full Text Available This work describes calibration methods for the particle sizing and particle concentration systems of the passive cavity aerosol spectrometer probe (PCASP. Laboratory calibrations conducted over six years, in support of the deployment of a PCASP on a cloud physics research aircraft, are analyzed. Instead of using the many calibration sizes recommended by the PCASP manufacturer, a relationship between particle diameter and scattered light intensity is established using three sizes of mobility-selected polystyrene latex particles, one for each amplifier gain stage. In addition, studies of two factors influencing the PCASP's determination of the particle size distribution – amplifier baseline and particle shape – are conducted. It is shown that the PCASP-derived size distribution is sensitive to adjustments of the sizing system's baseline voltage, and that for aggregates of spheres, a PCASP-derived particle size and a sphere-equivalent particle size agree within uncertainty dictated by the PCASP's sizing resolution. Robust determinations of aerosol concentration, and size distribution, also require calibration of the PCASP's aerosol flowrate sensor. Sensor calibrations, calibration drift, and the sensor's non-linear response are documented.

  2. Calibration of the passive cavity aerosol spectrometer probe for airborne determination of the size distribution

    Directory of Open Access Journals (Sweden)

    Y. Cai

    2013-05-01

    Full Text Available This work describes calibration methods for the particle sizing and particle concentration systems of the passive cavity aerosol spectrometer probe (PCASP. Laboratory calibrations conducted over six years, in support of the deployment of a PCASP on a cloud physics research aircraft, are analyzed. Instead of using the many calibration sizes recommended by the PCASP manufacturer, a relationship between particle diameter and scattered light intensity is established using three sizes of mobility-selected polystyrene latex particles, one for each amplifier gain stage. In addition, studies of two factors influencing the PCASP's determination of the particle size distribution – amplifier baseline and particle shape – are conducted. It is shown that the PCASP-derived size distribution is sensitive to adjustments of the sizing system's baseline voltage, and that for aggregate spheres, a PCASP-derived particle size and a sphere-equivalent particle size agree within uncertainty dictated by the PCASP's sizing resolution. Robust determination of aerosol concentration, and size distribution, also require calibration of the PCASP's aerosol flowrate sensor. Sensor calibrations, calibration drift, and the sensor's non-linear response are documented.

  3. Iteration method for the inversion of simulated multiwavelength lidar signals to determine aerosol size distribution

    Institute of Scientific and Technical Information of China (English)

    Tao Zong-Ming; Zhang Yin-Chao; Liu Xiao-Qin; Tan Kun; Shao Shi-Sheng; Hu Huan-Ling; Zhang Gai-Xia; Lü Yong-Hui

    2004-01-01

    A new method is proposed to derive the size distribution of aerosol from the simulated multiwavelength lidar extinction coefficients. The basis for this iteration is to consider the extinction efficiency factor of particles as a set of weighting function covering the entire radius region of a distribution. The weighting functions are calculated exactly from Mie theory. This method extends the inversion region by subtracting some extinction coefficient. The radius range of simulated size distribution is 0.1-10.0μm, the inversion radius range is 0.1-2.0μm, but the inverted size distributions are in good agreement with the simulated one.

  4. Size-resolved and bulk activation properties of aerosols in the North China plain: the importance of aerosol size distribution in the prediction of CCN number concentration

    Directory of Open Access Journals (Sweden)

    Z. Z. Deng

    2011-01-01

    Full Text Available Size-resolved and bulk activation properties of aerosols were measured at a regional/suburban site in the North China Plain (NCP, which is occasionally heavily polluted by anthropogenic aerosol particles and gases. A CCN (Cloud Condensation Nuclei closure study is conducted with bulk CCN number concentration (NCCN and calculated NCCN based on the aerosol number size distribution and size-resolved activation properties.

    The observed NCCN are higher than those observed in other locations than China, with average NCCN of roughly 2000, 3000, 6000, 10 000 and 13 000 cm−3 at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.70%, respectively. An inferred critical dry diameter (Dm is calculated based on the measured NCCN and aerosol number size distribution assuming homogeneous chemical composition. This inferred cut off diameter varies in a wide range, indicating that it is impossible to predict NCCN with a fixed critical diameter.

    Size-resolved activation measurements show that most of the 300 nm particles are activated at the investigated supersaturations, while almost no particles of 30 nm are activated even at the highest supersaturation of 0.72%. The activation ratio increases with increasing supersaturation and particle size. The slopes of the activation curves for ambient aerosols are not as steep as those observed in calibrations with ammonium sulfate suggesting that the observed aerosols is an external mixture of more hygroscopic and hydrophobic particles. This conclusion is confirmed by hygroscopicity measurements performed during two intensive field studies in 2009.

    The calculated NCCN based on the size-resolved activation ratio and aerosol number size distribution correlate well with the measured NCCN, and show an average overestimation

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

    International Nuclear Information System (INIS)

    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 aM 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 PM2.5 and PM1.0) can be potentially affected by inappropriate assumption on the particle shape

  6. [Determination of the retrieval arithmetic of aerosol size distribution measured by DOAS].

    Science.gov (United States)

    Si, Fu-qi; Xie, Pin-hua; Liu, Jian-guo; Zhang, Yu-jun; Liu, Wen-qing; Hiroaki, Kuze; Nobuo, Takeuchi

    2008-10-01

    Atmospheric aerosol is not only an important factor for the change in global climate, but also a polluting matter. Moreover, aerosol plays a main role in chemical reaction of polluting gases. Determination of aerosol has become an important re- search in the study of atmospheric environment. Differential optical absorption spectroscopy (DOAS) is a very useful technique that allows quantitative measurement of atmospheric trace gas concentrations based on their fingerprint absorption. It also can be used to retrieve aerosol extinction coefficient. In the present work, the method of determination of aerosol size distribution measured by flash DOAS is described, and the arithmetic based on Monte-Carlo is the emphasis. By comparison with the concentration of PM10, visibility and Angstrom wavelength exponent, a good correlation can be found. Application of DOAS in aerosol field not only provides a novel method for aerosol detection, but also extends the field of application of DOAS technology. Especially, aerosol DOAS plays an important role in the study of atmospheric chemistry. PMID:19123420

  7. 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 ostatní: MF NF(CZ) CZ0049 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z10300504 Keywords : atmospheric aerosols * atmospheric nucleation * part size distribution Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.911, year: 2011

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

    Science.gov (United States)

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

    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 (~15-15,000nm) 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 <100nm) 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 167nm and 1150 to 1760nm 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

  9. Based on particle size distribution of radioactive aerosol of screen diffusion battery measuring software

    International Nuclear Information System (INIS)

    Based on screen diffusion battery of particle size distribution of the radioactive aerosol measuring system developed a measurement and analysis software, the software operating environment was the embedded ARM-based hardware system and embedded linux operating system. The software is developed by the open source package QT. System functions included the measurement process control, screen diffusion battery transmittance calculations, particle size distribution measurement, measurement data analysed by the EM algorithm and Twomey algorithms, particle size distribution showed, system communication and other functions. (authors)

  10. Size-resolved CCN distributions and activation kinetics of aged continental and marine aerosol

    Directory of Open Access Journals (Sweden)

    A. Bougiatioti

    2011-04-01

    Full Text Available We present size-segregated measurements of cloud condensation nucleus (CCN activity of aged aerosol sampled at Finokalia, Crete, during the Finokalia Aerosol Measurement Experiment of summer 2007 (FAME07. From analysis of the data, hygroscopicity and activation kinetics distributions are derived. The CCN are found to be highly hygroscopic, (expressed by a size- and time-averaged hygroscopicity parameter κ ~ 0.22, with the majority of particles activating at ~0.5–0.6% supersaturation. Air masses originating from Central-Eastern Europe tend to be associated with higher CCN concentrations and slightly lower hygroscopicity (κ ~ 0.18 than for other airmass types. The particles were always well mixed, as reflected by the high activation ratios and narrow hygroscopicity distribution widths. Smaller particles (~30 nm were found to be more hygroscopic (~0.1 κ units higher than the larger ones (~100 nm. The particles with diameters less than 80 nm exhibited a diurnal hygroscopicity cycle (with κ peaking at ~14:00 h local time, consistent with photochemical aging and volatilization of less hygroscopic material from the aerosol. Use of bulk chemical composition and the aerosol number distribution results in excellent CCN closure when applying Köhler theory in its simplest form. Using asymptotic and threshold droplet growth analysis, the "aged" organics present in the aerosol were found not to suppress or delay the water uptake kinetics of particles in this environment.

  11. Changes in concentration and size distribution of aerosols during fog over the south Indian Ocean

    Indian Academy of Sciences (India)

    Vimlesh Pant; C G Deshpande; A K Kamra

    2010-08-01

    Measurements of the concentration and size distribution of aerosol particles in the size-ranges of 0.5–20 m and 16–700 nm diameters were made during six fog episodes over the south Indian Ocean. Observations show that concentrations of particles of all sizes start decreasing 1–2 hours before the occurrence of fog. This decrease is more prominent for coarse particles of < 1 m diameter and continues until 10–20 minutes before the onset of fog when particle concentrations in all size ranges rapidly increase by one/two orders of magnitude in ∼20 minutes. Thereafter, concentrations of particles of all sizes gradually decrease until the dissipation of fog. After the fog dissipation, concentrations of coarse mode particles rapidly increase and restore to their pre-fog levels but concentrations of the Aitken mode particles decrease slowly and reach their pre-fog levels only after 1–2 hours. The net effect of fog is to change the bimodal size distributions of aerosols with a coarse mode at 1.0 m and an accumulation mode at 40–60 nm to a power law size distribution. It is proposed that the preferential growth and sedimentation of the coarse mode hygroscopic particles in the initial phase cause a large decrease in the aerosol surface area. As a result, the low vapour pressure gases which were initially being used for the growth of coarse mode particles, now accelerate the growth rates of the accumulation and Aitken mode particles.

  12. Chemical Composition and Size Distributions of Coastal Aerosols Observed on the U.S. East Coast

    Science.gov (United States)

    Xia, L.; Song, F.; Jusino-Atresino, R.; Thuman, C.; Gao, Y.

    2008-12-01

    Aerosol input is an important source of certain limiting nutrients, such as iron, for phytoplankton growth in several large oceanic regions. As the efficiency of biological uptake of nutrients may depend on the aerosol properties, a better knowledge of aerosol properties is critically important. Characterizing aerosols over the coastal ocean needs special attention, because the properties of aerosols could be altered by many anthropogenic processes in this land-ocean transition zone before they are transported over the remote ocean. The goal of this experiment was to examine aerosol properties, in particular chemical composition, particle-size distributions and iron solubility, over the US Eastern Seaboard, an important boundary for the transport of continental substances from North America to the North Atlantic Ocean. Our field sampling site was located at Tuckerton (39°N, 74°W) on the southern New Jersey coast. Fourteen sets of High-Volume aerosol samples and three sets of size segregated aerosol samples by a 10-stage MOUDI impactor were collected during 2007 and 2008. The ICP-MS methodology was used to analyze aerosol samples for the concentrations of thirteen trace elements: Al, Fe, Mn, Sc, Cd, Pb, Sb, Ni, Co, Cr, Cu, Zn and V. The IC procedures were applied to determine five cations (sodium, ammonium, potassium, magnesium and calcium) and eleven anions (fluoride, acetate, propionate, formate, MSA, chloride, nitrate, succinate, malonate, sulfate and oxalate). The UV spectrometry was employed for the determination of iron solubility. Preliminary results suggest three major sources of aerosols: anthropogenic, crustal and marine. At this location, the concentrations of iron (II) ranged from 2.8 to 29ng m-3, accounting for ~20% of the total iron. The iron concentrations at this coastal site were substantially lower than those observed in Newark, an urban site in northern NJ. High concentrations of iron (II) were associated with both fine and coarse aerosol

  13. 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 ostatní: 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

  14. 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.

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

    KAUST Repository

    Khan, Basit

    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.

  16. Chemical Size Distribution of Suburban Aerosol Sampled in Prague 2008 Using Humidity Controlled Inlets

    Czech Academy of Sciences Publication Activity Database

    Štefancová, Lucia; Schwarz, Jaroslav; Maenhaut, W.; Chi, X.; Smolík, Jiří

    Prague : Orgit, 2009 - (Smolík, J.; O'Dowd, C.), s. 155-158 ISBN 978-80-02-12161-2. [International Conference Nucleation and Atmospheric Aerosols /18./. Prague (CZ), 10.08.2009-14.08.2009] R&D Projects: GA MŠk OC 106; GA MŠk ME 941 Institutional research plan: CEZ:AV0Z40720504 Keywords : mass-size distribution * chemical composition * atmospheric aerosols Subject RIV: CF - Physical ; Theoretical Chemistry http://www.icnaa.cz/

  17. Mass Size Distribution of Atmospheric Aerosols and Water Soluble Ions atMlada Boleslav in Winter

    Czech Academy of Sciences Publication Activity Database

    Schwarz, Jaroslav; Zíková, Naděžda; Vodička, Petr; Hovorka, J.; Moravec, Pavel; Ždímal, Vladimír

    Praha : Czech Aerosol Society, 2013 - (Zíková, N.), s. 13-14 ISBN 978-80-86186-52-8. [Výroční konference České aerosolové společnosti /14./. Nový Smokovec, High Tatras (SK), 23.10.2013-25.10.2013] R&D Projects: GA ČR(CZ) GBP503/12/G147 Institutional support: RVO:67985858 Keywords : atmospheric aerosols * mass size distribution * water soluble ions Subject RIV: DI - Air Pollution ; Quality

  18. Detailed mass size distributions of atmospheric aerosol species in the Negev desert, Israel, during ARACHNE-96

    International Nuclear Information System (INIS)

    As part of the 1996 summer intensive of the Aerosol, RAdiation and CHemistry Experiment (ARACHNE-96), the mass size distribution of various airborne particulate elements was studied at a remote site in the Negev Desert, Israel. Aerosol collections were made with 8-stage PIXE International cascade impactors (PCIs) and 12-stage small deposit area low pressure impactors (SDIs) and the samples were analyzed by PIXE for about 20 elements. The mineral elements (Al, Si, Ca, Ti, Fe) exhibited a unimodal size distribution which peaked at about 6 μm, but the contribution of particles larger than 10 μm was clearly more pronounced during the day than during night. Sulphur and Br had a tendency to exhibit two modes in the submicrometer size range, with diameters at about 0.3 and 0.6 μm, respectively. The elements V and Ni, which are indicators of residual fuel burning, showed essentially one fine mode (at 0.3 μm) in addition to a coarse mode which represented the mineral dust contribution. Overall, good agreement was observed between the mass size distributions from the PCI and SDI devices. The PCI was superior to the SDI for studying the size distribution in the coarse size range, but the SDI was clearly superior for unravelling the various modes in the submicrometer size range

  19. A mica microfilter cascade fractionator used to obtain aerosol size distribution

    International Nuclear Information System (INIS)

    Aerosols produced at KfK-SASCHA facility were filtered with a Cascade Fractionator containing four mica microfilters. The aerosol particles were measured. The results are compared with those obtained with another method and show that the Cascade Fractionator is a useful tool for aerosol fractionation and measurement of aerosol particle sizes. (author)

  20. Simplifying aerosol size distributions modes simultaneously detected at four monitoring sites during SAPUSS

    Directory of Open Access Journals (Sweden)

    M. Brines

    2013-10-01

    Full Text Available The analysis of aerosol size distributions is a useful tool for understanding the sources and the processes influencing particle number concentrations (N in urban areas. Hence, during the one month SAPUSS campaign (Solving Aerosol Problems by Using Synergistic Strategies, EU Marie Curie Action in autumn 2010 in Barcelona (Spain, four SMPS (Scanning Mobility Particle Sizers were simultaneously deployed at four monitoring sites: a road side (RSsite, an urban background site located in the city (UBsite, an urban background located in the nearby hills of the city (Torre Collserola, TCsite and a regional background site located about fifty km from the Barcelona urban areas (RBsite. The spatial distribution of sites allows study of the aerosol temporal variability as well as the spatial distribution, progressively moving away from urban aerosol sources. In order to interpret the datasets collected, a k-means cluster analysis was performed on the combined SMPS datasets. This resulted in nine clusters describing all aerosol size distributions from the four sites. In summary there were three main categories (with three clusters in each category: "Traffic" (Traffic 1 "Tclus1" – 8%, Traffic 2 "Tclus2" – 13%, Traffic 3, "Tclus3" – 9%, "Background Pollution" (Urban Background 1 "UBclus1" – 21%, Regional Background 1, "RBclus1" – 15%, Regional Background 2, "RBclus2" – 18% and "Special cases" (Nucleation "NUclus" – 5%, Regional Nitrate, "NITclus" – 6%, and Mix "MIXclus" – 5%. As expected, the frequency of traffic clusters (Tclus1–3 followed the order RSsite, UBsite, TCsite, and RBsite. These showed typical traffic modes mainly distributed at 20–40 nm. The urban background sites (UBsite and TCsite reflected also as expected urban background number concentrations (average values, N = 2.4×104 cm−3 relative to 1.2×105 cm−3 seen at RSsite. The cluster describing the urban background pollution (UBclus1 could be used to monitor the sea

  1. Tropospheric aerosol size distributions simulated by three online global aerosol models using the M7 microphysics module

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    K. Zhang

    2010-03-01

    Full Text Available Tropospheric aerosol size distributions are simulated by three online global models that employ exactly the same modal approach but differ in many aspects such as model meteorology, natural aerosol emissions, sulfur chemistry, and the parameterization of deposition processes. The main purpose of this study is to identify where the largest inter-model discrepancies occur and what the main reasons are.

    The number concentrations of different aerosol size ranges are compared among the three models and against observations. Overall all the three models can capture the basic features of the observed aerosol number spatial distributions. The magnitude of the number concentration of each mode is consistent among the three models. Quantitative differences are also clearly detectable. For the soluble and insoluble coarse mode and accumulation mode, inter-model discrepancies mainly result from differences in the sea salt and dust emissions, as well as the different strengths of the convective transport in the meteorological models. For the nucleation mode and the soluble Aitken mode, the spread of the model results is largest in the tropics and in the middle and upper troposphere. Diagnostics and sensitivity experiments suggest that this large spread is closely related to the sulfur cycle in the models, which is strongly affected by the choice of sulfur chemistry scheme, its coupling with the convective transport and wet deposition calculation, and the related meteorological fields such as cloud cover, cloud water content, and precipitation.

    The aerosol size distributions simulated by the three models are compared to observations in the boundary layer. The characteristic shape and magnitude of the distribution functions are reasonably reproduced in typical conditions (i.e., clean, polluted and transition areas. Biases in the mode parameters over the remote oceans and the China adjacent seas are probably caused by the fixed mode variance

  2. 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.

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

    International Nuclear Information System (INIS)

    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.

  4. Aged boreal biomass-burning aerosol size distributions from BORTAS 2011

    Science.gov (United States)

    Sakamoto, K. M.; Allan, J. D.; Coe, H.; Taylor, J. W.; Duck, T. J.; Pierce, J. R.

    2015-02-01

    Biomass-burning aerosols contribute to aerosol radiative forcing on the climate system. The magnitude of this effect is partially determined by aerosol size distributions, which are functions of source fire characteristics (e.g. fuel type, MCE) and in-plume microphysical processing. The uncertainties in biomass-burning emission number-size distributions in climate model inventories lead to uncertainties in the CCN (cloud condensation nuclei) concentrations and forcing estimates derived from these models. The BORTAS-B (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellite) measurement campaign was designed to sample boreal biomass-burning outflow over eastern Canada in the summer of 2011. Using these BORTAS-B data, we implement plume criteria to isolate the characteristic size distribution of aged biomass-burning emissions (aged ~ 1-2 days) from boreal wildfires in northwestern Ontario. The composite median size distribution yields a single dominant accumulation mode with Dpm = 230 nm (number-median diameter) and σ = 1.5, which are comparable to literature values of other aged plumes of a similar type. The organic aerosol enhancement ratios (ΔOA / ΔCO) along the path of Flight b622 show values of 0.09-0.17 μg m-3 ppbv-1 (parts per billion by volume) with no significant trend with distance from the source. This lack of enhancement ratio increase/decrease with distance suggests no detectable net OA (organic aerosol) production/evaporation within the aged plume over the sampling period (plume age: 1-2 days), though it does not preclude OA production/loss at earlier stages. A Lagrangian microphysical model was used to determine an estimate of the freshly emitted size distribution corresponding to the BORTAS-B aged size distributions. The model was restricted to coagulation and dilution processes based on the insignificant net OA production/evaporation derived from the ΔOA / ΔCO enhancement ratios. We

  5. Aerosol size distribution and radiative forcing response to anthropogenically driven historical changes in biogenic secondary organic aerosol formation

    Directory of Open Access Journals (Sweden)

    S. D. D'Andrea

    2014-10-01

    Full Text Available Emissions of biogenic volatile organic compounds (BVOC have changed in the past millennium due to changes in land use, temperature and CO2 concentrations. Recent model reconstructions of BVOC emissions over the past millennium predicted changes in dominant secondary organic aerosol (SOA producing BVOC classes (isoprene, monoterpenes and sesquiterpenes. The reconstructions predicted that global isoprene emissions have decreased (land-use changes to crop/grazing land dominate the reduction, while monoterpene and sesquiterpene emissions have increased (temperature increases dominate the increases; however, all three show regional variability due to competition between the various influencing factors. These BVOC changes have largely been anthropogenic in nature, and land-use change was shown to have the most dramatic effect by decreasing isoprene emissions. In this work, we use two modeled estimates of BVOC emissions from the years 1000 to 2000 to test the effect of anthropogenic changes to BVOC emissions on SOA formation, global aerosol size distributions, and radiative effects using the GEOS-Chem-TOMAS global aerosol microphysics model. With anthropogenic emissions (e.g. SO2, NOx, primary aerosols held at present day values and BVOC emissions changed from year 1000 to year 2000 values, decreases in the number concentration of particles of size Dp > 80 nm (N80 of >25% in year 2000 relative to year 1000 were predicted in regions with extensive land-use changes since year 1000 which led to regional increases in direct plus indirect aerosol radiative effect of >0.5 W m−2 in these regions. We test the sensitivity of our results to BVOC emissions inventory, SOA yields and the presence of anthropogenic emissions; however, the qualitative response of the model to historic BVOC changes remains the same in all cases. Accounting for these uncertainties, we estimate millennial changes in BVOC emissions cause a global mean direct effect of between +0.022 and

  6. Characterization of size distributions of elemental mass concentrations in atmospheric aerosols derived from different sources

    International Nuclear Information System (INIS)

    The atmospheric aerosol samples were collected at six representative sites with an 8-stage cascade impactor sampler and analyzed for their elemental mass concentrations by the PIXE analytic method. Based on some indicator elements, the characteristic of size distributions of particles from different sources were obtained. According to these characteristics, we inferred the origins of the ultrafine particles around the Great Wall Station in the Antarctic. (orig.)

  7. Latitudinal aerosol size distribution variation in the Eastern Atlantic Ocean measured aboard the FS-Polarstern

    Directory of Open Access Journals (Sweden)

    P. I. Williams

    2006-12-01

    Full Text Available Aerosol size distribution measurements from 0.03 μm to 25 μm diameter were taken at ambient humidity aboard the German research vessel, FS-Polarstern, during a transect from Bremerhaven in northern Germany, to Cape Town in South Africa across latitudes 53°32' N to 33°55' S, denoted cruise number ANT XXI/1. The data were segregated according to air mass history, wind speed and latitude. Under clean marine conditions, the averaged size distributions were generally in good agreement with those reported previously for diameters less than 0.5 μm and can be approximated by two log-normal modes, with significant variation in the mean modal diameters. Two short periods of tri-modal behaviour were observed. Above 0.5 μm, there is indication of a limit to the mechanical generation of marine aerosol over the range of wind speeds observed. A new technique to determine the errors associated with aerosol size distribution measurements using Poisson statistics has been applied to the dataset, providing a tool to determine the necessary sample or averaging times for correct interpretation of such data. Finally, the data were also used to investigate the loss rate of condensing gases with potentially important consequences for heterogeneous marine photochemical cycles.

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

    Science.gov (United States)

    Panwar, Chhagan; Vyas, B. M.

    2016-05-01

    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 (Reff), integrated content of total aerosols (Nt), columnar content of accumulation and coarse size aerosols particles concentration (Na) (size 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 1013 m2 μm-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 1010 to 1011 m2/μm-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 1012 m2μm-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 (0.4 to 0.6 µm) in cold months. Several other interesting features of changing nature of monthly spectral AOT, Reff, Nt, Na and NC (particles/m2) have been discussed in detail in this paper.

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

    International Nuclear Information System (INIS)

    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. - Highlights: • Bimodal PSDs are retrieved by ACO based on probability density function accurately. • J-SB and M-β functions can be used as the versatile function to recover bimodal PSDs. • Bimodal aerosol PSDs can be estimated by J-SB function more reasonably

  10. Modal structure of chemical mass size distribution in the high Arctic aerosol

    Science.gov (United States)

    Hillamo, Risto; Kerminen, Veli-Matti; Aurela, Minna; MäKelä, Timo; Maenhaut, Willy; Leek, Caroline

    2001-11-01

    Chemical mass size distributions of aerosol particles were measured in the remote marine boundary layer over the central Arctic Ocean as part of the Atmospheric Research Program on the Arctic Ocean Expedition 1996 (AOE-96). An inertial impaction method was used to classify aerosol particles into different size classes for subsequent chemical analysis. The particle chemical composition was determined by ion chromatography and by the particle-induced X-ray emission technique. Continuous particle size spectra were extracted from the raw data using a data inversion method. Clear and varying modal structures for aerosols consisting of primary sea-salt particles or of secondary particles related to dimethyl sulfide emissions were found. Concentration levels of all modes decreased rapidly when the distance from open sea increased. In the submicrometer size range the major ions found by ion chromatography were sulfate, methane sulfonate, and ammonium. They had most of the time a clear Aitken mode and one or two accumulation modes, with aerodynamic mass median diameters around 0.1 μm, 0.3 μm, and between 0.5-1.0 μm, respectively. The overall submicron size distributions of these three ions were quite similar, suggesting that they were internally mixed over most of this size range. The corresponding modal structure was consistent with the mass size distributions derived from the particle number size distributions measured with a differential mobility particle sizer. The Aitken to accumulation mode mass ratio for nss-sulfate and MSA was substantially higher during clear skies than during cloudy periods. Primary sea-salt particles formed a mode with an aerodynamic mass median diameter around 2 μm. In general, the resulting continuous mass size distributions displayed a clear modal structure consistent with our understanding of the two known major source mechanisms. One is the sea-salt aerosol emerging from seawater by bubble bursting. The other is related to

  11. 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)

  12. 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.

  13. Urban aerosol size distributions over the Mediterranean city of Barcelona, NE Spain

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    M. Dall'Osto

    2012-11-01

    Full Text Available Differential mobility particle sizer (DMPS aerosol concentrations (N13-800 were collected over a one-year-period (2004 at an urban background site in Barcelona, North-Eastern Spain. Quantitative contributions to particle number concentrations of the nucleation (33–39%, Aitken (39–49% and accumulation mode (18–22% were estimated. We examined the source and time variability of atmospheric aerosol particles by using both K-means clustering and Positive Matrix Factorization (PMF analysis. Performing clustering analysis on hourly size distributions, nine K-means DMPS clusters were identified and, by directional association, diurnal variation and relationship to meteorological and pollution variables, four typical aerosol size distribution scenarios were identified: traffic (69% of the time, dilution (15% of the time, summer background conditions (4% of the time and regional pollution (12% of the time. According to the results of PMF, vehicle exhausts are estimated to contribute at least to 62–66% of the total particle number concentration, with a slightly higher proportion distributed towards the nucleation mode (34% relative to the Aitken mode (28–32%. Photochemically induced nucleation particles make only a small contribution to the total particle number concentration (2–3% of the total, although only particles larger than 13 nm were considered in this study. Overall the combination of the two statistical methods is successful at separating components and quantifying relative contributions to the particle number population.

  14. Urban aerosol size distributions over the Mediterranean city of Barcelona, NE Spain

    Directory of Open Access Journals (Sweden)

    M. Dall'Osto

    2012-07-01

    Full Text Available Differential mobility particle sizer (DMPS aerosol concentrations (N13–800 were collected over a one-year-period (2004 at an urban background site in Barcelona, North-Eastern Spain. Quantitative contributions to particle number concentrations of the nucleation (33–38%, Aitken (39–49% and accumulation mode (18–22% were estimated. We examined the source and time variability of atmospheric aerosol particles by using both K-means clustering and Positive Matrix Factorization (PMF analysis. Performing clustering analysis on hourly size distributions, nine K-means DMPS clusters were identified and, by directional association, diurnal variation and relationship to meteorological and pollution variables, four typical aerosol size distribution scenarios were identified: traffic (69% of the time, dilution (15% of the time, summer background conditions (4% of the time and regional pollution (12% of the time. According to the results of PMF, vehicle exhausts are estimated to contribute at least to 62–66% of the total particle number concentration, with a slightly higher proportion distributed towards the nucleation mode (34% relative to the Aitken mode (28–32%. Photochemically induced nucleation particles make only a small contribution to the total particle number concentration (2–3% of the total, although only particles larger than 13 nm were considered in this study. Overall the combination of the two statistical methods is successful at separating components and quantifying relative contributions to the particle number population.

  15. Methodology for measuring exhaust aerosol size distributions using an engine test under transient operating conditions

    International Nuclear Information System (INIS)

    A study on the sources of variability in the measurement of particle size distribution using a two-stage dilution system and an engine exhaust particle sizer was conducted to obtain a comprehensive and repeatable methodology that can be used to measure the particle size distribution of aerosols emitted by a light-duty diesel engine under transient operating conditions. The paper includes three experimental phases: an experimental validation of the measurement method; an evaluation of the influence of sampling factors, such as dilution system pre-conditioning; and a study of the effects of the dilution conditions, such as the dilution ratio and the dilution air temperature. An examination of the type and degree of influence of each studied factor is presented, recommendations for reducing variability are given and critical parameter values are identified to develop a highly reliable measurement methodology that could be applied to further studies on the effect of engine operating parameters on exhaust particle size distributions

  16. Software for retrieval of aerosol particle size distribution from multiwavelength lidar signals

    Science.gov (United States)

    Sitarek, S.; Stacewicz, T.; Posyniak, M.

    2016-02-01

    Software to retrieve profiles of aerosol particle size distribution (APSD) from multiwavelength lidar signals is presented. The approach consists in direct fit of artificial signal generated using predefined distribution to the experimental signals. Combination of two lognormal functions with a few free parameters is applied for the predefined APSD. The minimization technique allows finding lognormal function parameters which provide the best fit. The approach was tested on the experimental signals registered at 1064, 532 and 355 nm. The software is designated for processing on PCs. The computation time was about several minutes.

  17. The importance of interstitial particle scavenging by cloud droplets in shaping the remote aerosol size distribution and global aerosol-climate effects

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    J. R. Pierce

    2015-02-01

    Full Text Available In this paper, we investigate the coagulation of interstitial aerosol particles (particles too small to activate to cloud droplets with cloud drops, a process often ignored in aerosol-climate models. We use the GEOS-Chem-TOMAS global chemical transport model with aerosol microphysics to calculate the changes in the aerosol size distribution, cloud-albedo aerosol indirect effect, and direct aerosol effect due to the interstitial coagulation process. We find that inclusion of interstitial coagulation in clouds lowers total particle number concentrations by 15–21% globally, where the range is due to varying assumptions regarding activation diameter, cloud droplet size, and ice cloud physics. The interstitial coagulation process lowers the concentration of particles with dry diameters larger than 80 nm (a proxy for larger CCN by 10–12%. These 80 nm particles are not directly removed by the interstitial coagulation, but are reduced in concentration because fewer smaller particles grow to diameters larger than 80 nm. The global aerosol indirect effect of adding interstitial coagulation varies from +0.4 to +1.3 W m−2 where again the range depends on our cloud assumptions. Thus, the aerosol indirect effect of this process is significant, but the magnitude depends greatly on assumptions regarding activation diameter, cloud droplet size, and ice cloud physics. The aerosol direct effect of interstitial coagulation process is minor (−2 due to the shift in the aerosol size distribution at sizes where scattering is most effective being small. We recommend that this interstitial scavenging process be considered in aerosol models when the size distribution and aerosol indirect effects are important.

  18. Relationship Between Aerosol Number Size Distribution and Atmospheric Electric Potential Gradient in an Urban Area

    Science.gov (United States)

    Wright, Matthew; Matthews, James; Bacak, Asan; Silva, Hugo; Priestley, Michael; Percival, Carl; Shallcross, Dudley

    2016-04-01

    Small ions are created in the atmosphere by ground based radioactive decay and solar and cosmic radiation ionising the air. The ionosphere is maintained at a high potential relative to the Earth due to global thunderstorm activity, a current from the ionosphere transfers charge back to the ground through the weakly ionised atmosphere. A potential gradient (PG) exists between the ionosphere and the ground that can be measured in fair weather using devices such as an electric field mill. PG is inversely-proportional to the conductivity of the air and therefore to the number of ions of a given electrical mobility; a reduction of air ions will cause an increase of PG. Aerosols in the atmosphere act as a sink of air ions with an attachment rate dependent on aerosol size distribution and ion mobility. These relationships have been used to infer high particulate, and hence pollution, levels in historic datasets of atmospheric PG. A measurement campaign was undertaken in Manchester, UK for three weeks in July and August where atmospheric PG was measured with an electric field mill (JCI131, JCI Chilworth) on a second floor balcony, aerosol size distribution measured with a scanning mobility particle sizer (SMPS, TSI3936), aerosol concentration measured with a condensation particle counter (CPC, Grimm 5.403) and local meteorological measurements taken on a rooftop measurement site ~200 m away. Field mill and CPC data were taken at 1 s intervals and SMPS data in 2.5 minute cycles. Data were excluded for one hour either side of rainfall as rainclouds and droplets can carry significant charge which would affect PG. A quantity relating to the attachment of ions to aerosol (Ion Sink) was derived from the effective attachment coefficient of the aerosols. Further measurements with the field mill and CPC were taken at the same location in November 2015 when bonfire events would be expected to increase aerosol concentrations. During the summer measurements, particle number count (PNC

  19. Number size distribution measurements of biological aerosols under contrasting environments and seasons from southern tropical India

    Science.gov (United States)

    Valsan, Aswathy; Cv, Biju; Krishna, Ravi; Huffman, Alex; Poschl, Ulrich; Gunthe, Sachin

    2016-04-01

    Biological aerosols constitute a wide range of dead and alive biological materials and structures that are suspended in the atmosphere. They play an important role in the atmospheric physical, chemical and biological processes and health of living being by spread of diseases among humans, plants, and, animals. The atmospheric abundance, sources, physical properties of PBAPs as compared to non-biological aerosols, however, is poorly characterized. Though omnipresent, their concentration and composition exhibit large spatial and temporal variations depending up on their sources, land-use, and local meteorology. The Indian tropical region, which constitutes approximately 18% of the world's total population exhibits vast geographical extend and experiences a distinctive meteorological phenomenon by means of Indian Summer Monsoon (IMS). Thus, the sources, properties and characteristics of biological aerosols are also expected to have significant variations over the Indian subcontinent depending upon the location and seasons. Here we present the number concentration and size distribution of Fluorescent Biological Aerosol Particles (FBAP) from two contrasting locations in Southern tropical India measured during contrasting seasons using Ultra Violet Aerodynamic Particle Sizer (UV-APS). Measurements were carried out at a pristine high altitude continental site, Munnar (10.09 N, 77.06 E; 1605 m asl) during two contrasting seasons, South-West Monsoon (June-August, 2014) and winter (Jan - Feb, 2015) and in Chennai, a coastal urban area, during July - November 2015. FBAP concentrations at both the locations showed large variability with higher concentrations occurring at Chennai. Apart from regional variations, the FBAP concentrations also exhibited variations over two different seasons under the same environmental condition. In Munnar the FBAP concentration increased by a factor of four from South-West Monsoon to winter season. The average size distribution of FBAP at both

  20. 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

  1. Concentrations, size distributions and temporal variations of fluorescent biological aerosol particles in southern tropical India

    Science.gov (United States)

    Valsan, Aswathy; Krishna R, Ravi; CV, Biju; Huffman, Alex; Poschl, Ulrich; Gunthe, Sachin

    2015-04-01

    Biological aerosols constitute a wide range of dead and alive biological materials and structures that are suspended in the atmosphere. They play an important role in the atmospheric physical, chemical and biological processes and health of living being by spread of diseases among humans, plants, and, animals. The atmospheric abundance, sources, physical properties of PBAPs as compared to non-biological aerosols, however, is poorly characterized. The Indian tropical region, where large fraction of the world's total population is residing, experiences a distinctive meteorological phenomenon by means of Indian Summer Monsoon (IMS). Thus, the properties and characteristics of biological aerosols are also expected to be very diverse over the Indian subcontinent depending upon the seasons. Here we characterize the number concentration and size distribution of Fluorescent Biological Aerosol Particles (FBAP) at a high altitude continental site, Munnar (10.09 N, 77.06 E; 1605 m asl) in South India during the South-West monsoon, which constitute around 80 percent of the annual rainfall in Munnar. Continuous three months measurements (from 01 June 2014 to 21 Aug 2104) FBAPs were carried out at Munnar using Ultra Violet Aerodynamic Particle Sizer (UVAPS) during IMS. The mean number and mass concentration of coarse FBAP averaged over the entire campaign was 1.7 x 10-2 cm-3 and 0.24 µg m-3 respectively, which corresponds to 2 percent and 6 percent of total aerosol particle number and mass concentration. In agreement to other previous measurements the number size distribution of FBAP also peaks at 3.2 micron indicating the strong presence of fungal spores. This was also supported by the Scanning Electron Microscopic analysis of bioaerosols on filter paper. They also displayed a strong diurnal cycle with maximum concentration occurring at early morning hours. During periods of heavy and continuous rain where the wind is consistently blowing from South-West direction it was

  2. A Nanometer Aerosol Size Analyzer (nASA) for Rapid Measurement of High-concentration Size Distributions

    International Nuclear Information System (INIS)

    We have developed a fast-response nanometer aerosol size analyzer (nASA) that is capable of scanning 30 size channels between 3 and 100 nm in a total time of 3 s. The analyzer includes a bipolar charger (Po210), an extended-length nanometer differential mobility analyzer (Nano-DMA), and an electrometer (TSI 3068). This combination of components provides particle size spectra at a scan rate of 0.1 s per channel free of uncertainties caused by response-time-induced smearing. The nASA thus offers a fast response for aerosol size distribution measurements in high-concentration conditions and also eliminates the need for applying a de-smearing algorithm to resulting data. In addition, because of its thermodynamically stable means of particle detection, the nASA is useful for applications requiring measurements over a broad range of sample pressures and temperatures. Indeed, experimental transfer functions determined for the extended-length Nano-DMA using the tandem differential mobility analyzer (TDMA) technique indicate the nASA provides good size resolution at pressures as low as 200 Torr. Also, as was demonstrated in tests to characterize the soot emissions from the J85-GE engine of a T-38 aircraft, the broad dynamic concentration range of the nASA makes it particularly suitable for studies of combustion or particle formation processes. Further details of the nASA performance as well as results from calibrations, laboratory tests and field applications are presented below

  3. Simplifying aerosol size distributions modes simultaneously detected at four monitoring sites during SAPUSS

    Science.gov (United States)

    Brines, M.; Dall'Osto, M.; Beddows, D. C. S.; Harrison, R. M.; Querol, X.

    2014-03-01

    The analysis of aerosol size distributions is a useful tool for understanding the sources and the processes influencing particle number concentrations (N) in urban areas. Hence, during the one-month SAPUSS campaign (Solving Aerosol Problems by Using Synergistic Strategies, EU Marie Curie Action) in autumn 2010 in Barcelona (Spain), four SMPSs (Scanning Mobility Particle Sizer) were simultaneously deployed at four monitoring sites: a road side (RSsite), an urban background site located in the city (UBsite), an urban background site located in the nearby hills of the city (Torre Collserola, TCsite) and a regional background site located about 50 km from the Barcelona urban areas (RBsite). The spatial distribution of sites allows study of the aerosol temporal variability as well as the spatial distribution, progressively moving away from urban aerosol sources. In order to interpret the data sets collected, a k-means cluster analysis was performed on the combined SMPS data sets. This resulted in nine clusters describing all aerosol size distributions from the four sites. In summary there were three main categories (with three clusters in each category): "Traffic" (Traffic 1, "Tclus_1" - 8%; Traffic 2, "Tclus_2" - 13%; and Traffic 3, "Tclus_3" - 9%) "Background Pollution" (Urban Background 1, "UBclus_1" - 21%; Regional Background 1, "RBclus_1" - 15%; and Regional Background 2, "RBclus_2" - 18%) and "Special Cases" (Nucleation, "NUclus" - 5%; Regional Nitrate, "NITclus" - 6%; and Mix, "MIXclus" - 5%). As expected, the frequency of traffic clusters (Tclus_1-3) followed the order RSsite, UBsite, TCsite, and RBsite. These showed typical traffic modes mainly distributed at 20-40 nm. The urban background sites (UBsite and TCsite) reflected also as expected urban background number concentrations (average values, N = 1.0 × 104 cm-3 and N = 5.5 × 103 cm-3, respectively, relative to 1.3 × 104 cm-3 seen at RSsite). The cluster describing the urban background pollution (UBclus_1

  4. Size distributions and source function of sea spray aerosol over the South China Sea

    Science.gov (United States)

    Chu, Yingjia; Sheng, Lifang; Liu, Qian; Zhao, Dongliang; Jia, Nan; Kong, Yawen

    2016-08-01

    The number concentrations in the radius range of 0.06-5 μm of aerosol particles and meteorological parameters were measured on board during a cruise in the South China Sea from August 25 to October 12, 2012. Effective fluxes in the reference height of 10 m were estimated by steady state dry deposition method based on the observed data, and the influences of different air masses on flux were discussed in this paper. The number size distribution was characterized by a bimodal mode, with the average total number concentration of (1.50 ± 0.76)×103 cm-3. The two mode radii were 0.099 µm and 0.886 µm, both of which were within the scope of accumulation mode. A typical daily average size distribution was compared with that measured in the Bay of Bengal. In the whole radius range, the number concentrations were in agreement with each other; the modes were more distinct in this study than that abtained in the Bay of Bengal. The size distribution of the fluxes was fitted with the sum of log-normal and power-law distribution. The impact of different air masses was mainly on flux magnitude, rather than the shape of spectral distribution. A semiempirical source function that is applicable in the radius range of 0.06 µm< r 80<0.3 µm with the wind speed varying from 1.00 m s-1 to 10.00 m s-1 was derived.

  5. Characterization of Particle Size Distributions of Powdery Building Material Aerosol Generated by Fluidization and Gravitation

    Directory of Open Access Journals (Sweden)

    Tadas Prasauskas

    2012-10-01

    Full Text Available This study aims to identify particle size distributions (PSD of aerosol of powdery building materials commonly used in construction work (cement, chalk, clay, wood sawdust, wood grinding dust, gypsum, hydrated lime, masonry grout, quartz sand, sand and structural lime by two aerosolization methods: fluidization and gravitation. Fluidization and gravitation methods represent industrial activities such as pneumotransportation and unloading. Both particle resuspension mechanisms have been modelled in laboratory conditions. The particle size distributions of resuspended particulate matter from powdery building materials were rather similar identified by both fluidization and gravitation methods, with an exception of wood sawdust and sand. The PM10 fraction ranged between 30% and 87%, PM2.5 from 7% to 28% and PM1.0 from 3% to 7% of the total mass of particulate matter. The highest PM10/PMtotal ratio was calculated for masonry grout - 0.87, and the lowest ratio for quartz sand - 0.30. The highest ratio of PM2.5/PMtotal was calculated for sand - 0.23, the lowest for quartz sand - 0.07. Substantial quantities of PM2.5 were found to be emitted implying a potential threat to human health.DOI: http://dx.doi.org/10.5755/j01.erem.61.3.1519

  6. Aerosol size distribution characteristics of organosulfates in the Pearl River Delta region, China

    Science.gov (United States)

    Kuang, Bin Yu; Lin, Peng; Hu, Min; Yu, Jian Zhen

    2016-04-01

    Organosulfates (OSs) have been detected in various atmospheric environments, but their particle size distribution characteristics are unknown. In this work, we examined their size distributions in ambient aerosols to gain insights into the formation processes. Size-segregated aerosol samples in the range of 0.056-18 μm were collected using a ten-stage impactor at a receptor site in Hong Kong in both summer and winter and in Nansha in the Pearl River Delta in winter. The humic-like substances fraction in the size-segregated samples was isolated and analyzed using electrospray ionization coupled with an Orbitrap Ultra High Resolution Mass Spectrometer. Through accurate mass measurements, ∼190 CHOS and ∼90 CHONS formulas were tentatively identified to be OS compounds. Among them, OS compounds derived from isoprene, α-/β-pinene, and limonene and alkyl OSs having low double bond equivalents (DBE = 0,1) and 0-2 extra O beyond those in -OSO3 were found with high intensity. The biogenic volatile organic compounds-derived OS formulas share a common characteristic with sulfate in that the droplet mode dominated, peaking in either 0.56-1.0 or 1.0-1.8 μm size bin, reflecting sulfate as their common precursor. Most of these OSs have a minor coarse mode, accounting for 0-45%. The presence of OSs on the coarse particles is hypothesized to be a result of OSs on small particle (OS to non-sea-salt sulfate present on the coarse particles were similar to those on particles OS compounds have a dominant droplet mode at the Hong Kong site, but a more significant coarse mode presence was observed for CnH2n+1O4S-, CnH2n-1O4S-, and CnH2n-1O5S- formulas in the Nansha site, possibly suggesting site-specific mixed secondary and primary sources for these formulas.

  7. Size distribution of aerosol particles produced during mining and processing uranium ore.

    Science.gov (United States)

    Mala, Helena; Tomasek, Ladislav; Rulik, Petr; Beckova, Vera; Hulka, Jiri

    2016-06-01

    The aerosol particle size distributions of uranium and its daughter products were studied and determined in the area of the Rožná mine, which is the last active uranium mine in the Czech Republic. A total of 13 samples were collected using cascade impactors from three sites that had the highest expected levels of dust, namely, the forefield, the end of the ore chute and an area close to workers at the crushing plant. The characteristics of most size distributions were very similar; they were moderately bimodal, with a boundary approximately 0.5 μm between the modes. The activity median aerodynamic diameter (AMAD) and geometric standard deviation (GSD) were obtained from the distributions beyond 0.39 μm, whereas the sizes of particles below 0.39 μm were not differentiated. Most AMAD and GSD values in the samples ranged between 3.5 and 10.5 μm and between 2.8 and 5.0, respectively. The geometric means of the AMADs and GSDs from all of the underground sampling sites were 4.2 μm and 4.4, respectively, and the geometric means of the AMADs and GSDs for the crushing plant samplings were 9.8 μm and 3.3, respectively. The weighted arithmetic mean of the AMADs was 4.9 μm, with a standard error of 0.7 μm, according to the numbers of workers at the workplaces. The activity proportion of the radon progeny to (226)Ra in the aerosol was 0.61. PMID:27032340

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

    International Nuclear Information System (INIS)

    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 131I, 134Cs, 137Cs, and 7Be aerosols. All distributions could be considered monomodal. The arithmetic means of the activity median aerodynamic diameters (AMADs) for artificial radionuclides and for 7Be were 0.43 and 0.41 μm with GDSs 3.6 and 3.0, respectively. The time course of the AMADs of 134Cs, 137Cs and 7Be in the sampled period showed a slight decrease at a significance level of 0.05, whereas the AMAD pertaining to 131I 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 (140Ba, 140La 141Ce, 144Ce, 95Zr and 95Nb) and volatile radionuclides (134Cs, 137Cs, 103Ru, 106Ru, 131I, and 132Te). 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. -- Highlights: • AMADs after the Fukushima and Chernobyl accidents in the Czech Rep. were determined. • The mean value of AMADs of the monitored nuclides from the NPP Fukushima was 0.43 μm. • Nuclides from the NPP Chernobyl fell into two categories – refractory and volatile. • The mean value of AMADs of volatile nuclides from the NPP Chernobyl was 0.51 μm. • AMADs of volatile nucl. from the NPP Chernobyl were 3× smaller than of the refractory radionuclides

  9. Multi-peak accumulation and coarse modes observed from AERONET retrieved aerosol volume size distribution in Beijing

    Science.gov (United States)

    Zhang, Ying; Li, Zhengqiang; Zhang, Yuhuan; Chen, Yu; Cuesta, Juan; Ma, Yan

    2016-08-01

    We present characteristic peaks of atmospheric columnar aerosol volume size distribution retrieved from the AErosol RObotic NETwork (AERONET) ground-based Sun-sky radiometer observation, and their correlations with aerosol optical properties and meteorological conditions in Beijing over 2013. The results show that the aerosol volume particle size distribution (VPSD) can be decomposed into up to four characteristic peaks, located in accumulation and coarse modes, respectively. The mean center radii of extra peaks in accumulation and coarse modes locate around 0.28 (±0.09) to 0.38 (±0.11) and 1.25 (±0.56) to 1.47 (±0.30) μm, respectively. The multi-peak size distributions are found in different aerosol loading conditions, with the mean aerosol optical depth (440 nm) of 0.58, 0.49, 1.18 and 1.04 for 2-, 3-I/II and 4-peak VPSD types, while the correspondingly mean relative humidity values are 58, 54, 72 and 67 %, respectively. The results also show the significant increase (from 0.25 to 0.40 μm) of the mean extra peak median radius in the accumulation mode for the 3-peak-II cases, which agrees with aerosol hygroscopic growth related to relative humidity and/or cloud or fog processing.

  10. Plume Aerosol Size Distribution Modeling and Comparisons to PrAIRie2005 Field Study Data

    Science.gov (United States)

    Cho, S.; Liggio, J.; Makar, P.; Li, S.; Racinthe, J.

    2006-12-01

    As part of the analysis phase of the PrAIRie2005 field study, the effects of different Edmonton-area emission sources on local air-quality are being examined. Four large coal-fired power-plants are located to the West of the city. Here, the effects of these power-plants on urban and regional air-quality will be examined, using both plume and regional air-quality models. During the last few decades, coal-fired power plants have been found to be as a major source of pollution, affecting public-health. According to NACEC (North American Commission for Environmental Corporation, 2001)'s report, 46 of the top 50 air polluters in North America were power plants. The importance of such sources has resulted in several attempts to improve understanding of the basic formation mechanisms of plume particulate matter. Sulphur dioxide contributes to acidifying emissions and to the production of secondary acidic aerosols that have been linked to a number of serious human health problems, acid rain and visibility (Seinfeld and Pandis, 1998; Hidy, 1984; Wilson and McMurray, 1981). Primary particulate matter originating directly from coal-fired power plants may also increase secondary particulate mass by providing a surface for sulphuric acid absorption . Environment Canada's PrAIRie2005 field study between August 12th and September 7th, 2005 included overflights and downwind measurements near the Edmonton powerplants (Wabamun, Sundance, Keephills and Genesee). The data collected consisted of particle size distributions, ozone, NOX, total mass and the chemical composition of fine particles. In order to investigate and improve our understanding of the formation mechanisms and physical properties of power-plant-generated aerosols in the Edmonton area, the Plume Aerosol Microphysical (PAM) model has been employed. This model accounts for gas-phase chemistry, aerosol microphysical processes (i.e. homogeneous/heterogeneous nucleation, condensation/evaporation and coagulation) and

  11. Aerosol size distribution and classification. February 1970-January 1990 (Citations from the NTIS data base). Report for February 1970-January 1990

    International Nuclear Information System (INIS)

    This bibliography contains citations concerning aerosol size distribution and classification pertaining to air pollution detection and health studies. Aerosol size measuring methods, devices, and apparatus are discussed. Studies of atmospheric, industrial, radioactive, and marine aerosols are presented. (This updated bibliography contains 226 citations, 80 of which are new entries to the previous edition.)

  12. Influence of flow rate on aerosol particle size distributions from pressurized and breath-actuated inhalers.

    Science.gov (United States)

    Smith, K J; Chan, H K; Brown, K F

    1998-01-01

    Particle size distribution of delivered aerosols and the total mass of drug delivered from the inhaler are important determinants of pulmonary deposition and response to inhalation therapy. Inhalation flow rate may vary between patients and from dose to dose. The Andersen Sampler (AS) cascade impactor operated at flow rates of 30 and 55 L/min and the Marple-Miller Impactor (MMI) operated at flow rates of 30, 55, and 80 L/min were used in this study to investigate the influence of airflow rate on the particle size distributions of inhalation products. Total mass of drug delivered from the inhaler, fine particle mass, fine particle fraction, percentage of nonrespirable particles, and amount of formulation retained within the inhaler were determined by ultraviolet spectrophotometry for several commercial bronchodilator products purchased in the marketplace, including a pressurized metered-dose inhaler (pMDI), breath-actuated pressurized inhaler (BAMDI), and three dry powder inhalers (DPIs), two containing salbutamol sulphate and the other containing terbutaline sulphate. Varying the flow rate through the cascade impactor produced no significant change in performance of the pressurized inhalers. Increasing the flow rate produced a greater mass of drug delivered and an increase in respirable particle mass and fraction from all DPIs tested. PMID:10346666

  13. Characteristics of aerosol size distributions and chemical compositions during wintertime pollution episodes in Beijing

    Science.gov (United States)

    Liu, Zirui; Hu, Bo; Zhang, Junke; Yu, Yangchun; Wang, Yuesi

    2016-02-01

    To characterize the features of particle pollution, continuous measurements of particle number size distributions and chemical compositions were performed at an urban site in Beijing in January 2013. The particle number and volume concentration from 14 nm to 1000 nm were (37.4 ± 15.3) × 103 cm- 3 and (85.2 ± 65.6) μm3 cm- 3, respectively. N-Ait (Aitken mode) particles dominated the number concentration, whereas N-Acc (accumulation mode) particles dominated the volume concentration. Submicron particles were generally characterized by a high content of organics and SO42 -, and a low level of NO3- and Cl-. Two types of pollution episodes were observed, characterized by the "explosive growth" (EXP) and "sustained growth" (SUS) of PM2.5. Fine particles greater than 100 nm dominated the volume concentration during the ends of these pollution episodes, shifting the maximum of the number size distribution from 60 nm to greater than 100 nm in a few hours (EXP) or a few days (SUS). Secondary transformation is the main reason for the pollution episodes; SO42 -, NO3- and NH4+ (SNA) accounted for approximately 42% (EXP) and greater than 60% (SUS) of the N-Acc particle mass increase. The size distributions of particulate organics and SNA varied on timescales of hours to days, the characteristics of which changed from bimodal to unimodal during the evolution of haze episodes. The accumulation mode (peaking at approximately 500-700 nm) was dominated by organics that appeared to be internally mixed with nitrate or sulfate. The sulfate was most likely formed via heterogeneous reactions, because the SOR was constant under dry conditions (RH 50%, suggesting an important contribution from heterogeneous reactions with abundant aerosol water under wet conditions. Finally, the correlations between [NO3-]/[SO42 -] and [NH4+]/[SO42 -] suggest that the homogenous reaction between HNO3 and NH3 dominated the formation of nitrate under conditions of lower aerosol acidity. Therefore

  14. Airship measurements of aerosol size distributions, cloud droplet spectra, and trace gas concentrations in the marine boundary layers

    Energy Technology Data Exchange (ETDEWEB)

    Frick, G.M.; Hoppel, W.A. (Naval Research Lab., Washington, DC (United States))

    1993-11-01

    The use of an airship as a platform to conduct atmospheric chemistry, aerosol, and cloud microphysical research is described, and results from demonstration flights made off the Oregon coast are presented. The slow speed of the airship makes it an ideal platform to do high-spatial resolution profiling both vertically and horizontally, and to measure large aerosol and cloud droplet distributions without the difficulties caused by high-speed aircraft sampling. A unique set of data obtained during the demonstration flights show the effect that processing marine boundary layer aerosol through stratus clouds has on the aerosol size distribution. Evidence of new particle formation (nucleation of particles) was also observed on about half the days on which flights were made. 11 refs., 9 figs., 1 tab.

  15. Size distribution of EC and OC in the aerosol of Alpine valleys during summer and winter

    Directory of Open Access Journals (Sweden)

    J.-L. Jaffrezo

    2005-01-01

    Full Text Available Collections of samples were conducted for the determination of the size distributions of EC and OC during the intensive sampling campaigns of the POVA program, in two Alpine valleys of the French Alps, in summer and in winter. The comparison of concentrations obtained for samples collected in parallel with impactor- and filter-based methods is rather positive with slopes of 0.95 and 0.76 for OC and EC, respectively and correlations close to 1 (0.92 and 0.90 for OC and EC, respectively, n=26. This is an indication that the correction of pyrolysis seems to work for the impactor samples despite non even deposits. The size distributions of the concentrations of EC and OC present large evolutions between winter and summer, and between a suburban and a rural site. In winter, an overwhelming proportion of the mass fraction of both species is found in the droplet and accumulation modes, often (but not always in association with sulfate and other chemical species resulting from secondary formation processes. Some indications of gas/particles exchanges can be found for the other parts of the size spectrum (the Aitken and super micron modes in the case of the rural site. In summer, the changes are more drastic with, according to the case, a dominant droplet or accumulation mode. Particularly at the rural site, the large extent of processing of the aerosol due to gas/particles exchanges is evident for the Aitken and super micron modes, with increasing of the OC mass fractions in these size ranges. All of these observations give indications on the degree of internal vs. external mixing of the species investigated in the different modes.

  16. Application of the LSQR algorithm in non-parametric estimation of aerosol size distribution

    Science.gov (United States)

    He, Zhenzong; Qi, Hong; Lew, Zhongyuan; Ruan, Liming; Tan, Heping; Luo, Kun

    2016-05-01

    Based on the Least Squares QR decomposition (LSQR) algorithm, the aerosol size distribution (ASD) is retrieved in non-parametric approach. The direct problem is solved by the Anomalous Diffraction Approximation (ADA) and the Lambert-Beer Law. An optimal wavelength selection method is developed to improve the retrieval accuracy of the ASD. The proposed optimal wavelength set is selected by the method which can make the measurement signals sensitive to wavelength and decrease the degree of the ill-condition of coefficient matrix of linear systems effectively to enhance the anti-interference ability of retrieval results. Two common kinds of monomodal and bimodal ASDs, log-normal (L-N) and Gamma distributions, are estimated, respectively. Numerical tests show that the LSQR algorithm can be successfully applied to retrieve the ASD with high stability in the presence of random noise and low susceptibility to the shape of distributions. Finally, the experimental measurement ASD over Harbin in China is recovered reasonably. All the results confirm that the LSQR algorithm combined with the optimal wavelength selection method is an effective and reliable technique in non-parametric estimation of ASD.

  17. Dust emission size distribution impact on aerosol budget and radiative forcing over the Mediterranean region: a regional climate model approach

    Directory of Open Access Journals (Sweden)

    P. Nabat

    2012-07-01

    Full Text Available The present study investigates the dust emission and load over the Mediterranean basin using the coupled-chemistry-aerosol regional climate model RegCM-4. The first step of this work focuses on dust particle emission size distribution modeling. We compare a parameterization in which the emission is based on the individual kinetic energy of the aggregates striking the surface to a recent parameterization based on an analogy with the fragmentation of brittle materials. The main difference between the two dust schemes concerns the mass proportion of fine aerosol which is reduced in the case of the new dust parameterization, with consequences for optical properties. At the episodic scale, comparisons between RegCM-4 simulations, satellite and ground-based data show a clear improvement using the new dust distribution in terms of Aerosol Optical Depth (AOD values and geographic gradients. These results are confirmed at the seasonal scale for the investigated year 2008. A multi-annual simulation is finally carried out using the new dust distribution over the period 2000–2009. This change of dust distribution has sensitive impacts on the simulated regional dust budget, notably dry dust deposition and the regional direct aerosol radiative forcing over the Mediterranean basin. This could clearly modify the possible effects of dust aerosols on the biogeochemical activity and climate of the Mediterranean basin. In particular, we find that the new size distribution produces a higher dust deposition flux, and smaller top of atmosphere (TOA dust radiative cooling.

  18. A scaling theory for the size distribution of emitted dust aerosols suggests climate models underestimate the size of the global dust cycle

    CERN Document Server

    Kok, Jasper F

    2010-01-01

    Mineral dust aerosols impact Earth's radiation budget through interactions with clouds, ecosystems, and radiation, which constitutes a substantial uncertainty in understanding past and predicting future climate changes. One of the causes of this large uncertainty is that the size distribution of emitted dust aerosols is poorly understood. The present study shows that regional and global circulation models (GCMs) overestimate the emitted fraction of clay aerosols (< 2 {\\mu}m diameter) by a factor of ~2 - 8 relative to measurements. This discrepancy is resolved by deriving a simple theoretical expression of the emitted dust size distribution that is in excellent agreement with measurements. This expression is based on the physics of the scale-invariant fragmentation of brittle materials, which is shown to be applicable to dust emission. Because clay aerosols produce a strong radiative cooling, the overestimation of the clay fraction causes GCMs to also overestimate the radiative cooling of a given quantity o...

  19. 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.

  20. Sensitivity Analysis for Aerosol Refractive Index and Size Distribution Estimation Methods Based on Polarized Atmospheric Irradiance Measurements

    Directory of Open Access Journals (Sweden)

    Kohei Arai

    2014-01-01

    Full Text Available Aerosol refractive index and size distribution estimations based on polarized atmospheric irradiance measurements are proposed together with its application to reflectance based vicarious calibration. A method for reflectance based vicarious calibration with aerosol refractive index and size distribution estimation using atmospheric polarization irradiance data is proposed. It is possible to estimate aerosol refractive index and size distribution with atmospheric polarization irradiance measured with the different observation angles (scattering angles. The Top of the Atmosphere (TOA or at-sensor radiance is estimated based on atmospheric codes with estimated refractive index and size distribution then vicarious calibration coefficient can be calculated by comparing to the acquired visible to near infrared instrument data onboard satellites. The estimated TOA radiance based on the proposed method is compared to that with aureole-meter based approach which is based on refractive index and size distribution estimated with solar direct, diffuse and aureole (Conventional AERONET approach. It is obvious that aureole-meter is not portable, heavy and large while polarization irradiance measurement instruments are light and small (portable size and weight.

  1. Aerosol particle size distributions at a traffic exposed site and an urban background location in Oporto, Portugal

    Directory of Open Access Journals (Sweden)

    César Oliveira

    2009-01-01

    Full Text Available Aerosol size distributions from 6 to 700 nm were measured simultaneously at an urban background site and a roadside station in Oporto. The particle number concentration was higher at the traffic exposed site, where up to 90% of the size spectrum was dominated by the nucleation mode. Larger aerosol mode diameters were observed in the urban background site possibly due to the coagulation processes or uptake of gases during transport. Factor analysis has shown that road traffic and the neighbour stationary sources localised upwind affect the urban area thought intra-regional pollutant transport.

  2. Size distribution and chemical composition of secondary organic aerosol formed from Cl-initiated oxidation of toluene

    Institute of Scientific and Technical Information of China (English)

    Mingqiang Huang; Weijun Zhang; Xuejun Gu; Changjin Hu; Weixiong Zhao; Zhenya Wang; Li Fang

    2012-01-01

    Secondary organic aerosol (SOA) formed from Cl-initiated oxidation of toluene was investigated in a home-made smog chamber.The size distribution and chemical composition of SOA particles were measured using aerodynamic particle sizer spectrometer and the aerosol laser time-of-flight mass spectrometer (ALTOFMS),respectively.According to a large number of single aerosol diameter and mass spectra,the size distribution and chemical composition of SOA were obtained statistically.Experimental results showed that SOA particles created by Cl-initiated oxidation of toluene is predominantly in the form of fine particles,which have diameters less than 2.5 μm (i.e.,PM2.5),and glyoxal,benzaldehyde,benzyl alcohol,benzoquinone,benzoic acid,benzyl hydroperoxide and benzyl methyl nitrate are the major products components in the SOA.The possible reaction mechanisms leading to these products are also proposed.

  3. Aerosol concentration and size distribution measured below, in, and above cloud from the DOE G-1 during VOCALS-REx

    Science.gov (United States)

    Kleinman, L. I.; Daum, P. H.; Lee, Y.-N.; Lewis, E. R.; Sedlacek, A. J., III; Senum, G. I.; Springston, S. R.; Wang, J.; Hubbe, J.; Jayne, J.; Min, Q.; Yum, S. S.; Allen, G.

    2011-06-01

    During the VOCALS Regional Experiment, the DOE G-1 aircraft was used to sample a varying aerosol environment pertinent to properties of stratocumulus clouds over a longitude band extending 800 km west from the Chilean coast at Arica. Trace gas and aerosol measurements are presented as a function of longitude, altitude, and dew point in this study. Spatial distributions are consistent with an upper atmospheric source for O3 and South American coastal sources for marine boundary layer (MBL) CO and aerosol, most of which is acidic sulfate in agreement with the dominant pollution source being SO2 from Cu smelters and power plants. Pollutant layers in the free troposphere (FT) can be a result of emissions to the north in Peru or long range transport from the west. At a given altitude in the FT (up to 3 km), dew point varies by 40 °C with dry air descending from the upper atmospheric and moist air having a BL contribution. Ascent of BL air to a cold high altitude results in the condensation and precipitation removal of all but a few percent of BL water along with aerosol that served as CCN. Thus, aerosol volume decreases with dew point in the FT. Aerosol size spectra have a bimodal structure in the MBL and an intermediate diameter unimodal distribution in the FT. Comparing cloud droplet number concentration (CDNC) and pre-cloud aerosol (Dp > 100 nm) gives a linear relation up to a number concentration of ~150 cm-3, followed by a less than proportional increase in CDNC at higher aerosol number concentration. A number balance between below cloud aerosol and cloud droplets indicates that ~25 % of aerosol in the PCASP size range are interstitial (not activated). One hundred and two constant altitude cloud transects were identified and used to determine properties of interstitial aerosol. One transect is examined in detail as a case study. Approximately 25 to 50 % of aerosol with Dp > 110 nm were not activated, the difference between the two approaches possibly representing

  4. Aerosol concentration and size distribution measured below, in, and above cloud from the DOE G-1 during VOCALS-REx

    Directory of Open Access Journals (Sweden)

    L. I. Kleinman

    2011-06-01

    Full Text Available During the VOCALS Regional Experiment, the DOE G-1 aircraft was used to sample a varying aerosol environment pertinent to properties of stratocumulus clouds over a longitude band extending 800 km west from the Chilean coast at Arica. Trace gas and aerosol measurements are presented as a function of longitude, altitude, and dew point in this study. Spatial distributions are consistent with an upper atmospheric source for O3 and South American coastal sources for marine boundary layer (MBL CO and aerosol, most of which is acidic sulfate in agreement with the dominant pollution source being SO2 from Cu smelters and power plants. Pollutant layers in the free troposphere (FT can be a result of emissions to the north in Peru or long range transport from the west. At a given altitude in the FT (up to 3 km, dew point varies by 40 °C with dry air descending from the upper atmospheric and moist air having a BL contribution. Ascent of BL air to a cold high altitude results in the condensation and precipitation removal of all but a few percent of BL water along with aerosol that served as CCN. Thus, aerosol volume decreases with dew point in the FT. Aerosol size spectra have a bimodal structure in the MBL and an intermediate diameter unimodal distribution in the FT. Comparing cloud droplet number concentration (CDNC and pre-cloud aerosol (Dp > 100 nm gives a linear relation up to a number concentration of ~150 cm−3, followed by a less than proportional increase in CDNC at higher aerosol number concentration. A number balance between below cloud aerosol and cloud droplets indicates that ~25 % of aerosol in the PCASP size range are interstitial (not activated. One hundred and two constant altitude cloud transects were identified and used to determine properties of interstitial aerosol. One transect is examined in detail as a case study. Approximately 25 to 50 % of aerosol with Dp > 110 nm

  5. Aerosol particle size distribution in building and caves: impact to the radon-related dose evaluation

    International Nuclear Information System (INIS)

    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.)

  6. Measurement and Analysis of Near Real Time Data on Particle Size Distribution in Atmospheric Aerosol

    Czech Academy of Sciences Publication Activity Database

    Wagner, Zdeněk; Fridrich, Miroslav; Schwarz, Jaroslav; Ždímal, Vladimír; Váňa, M.

    Catalogue : Zagreb Inventors Association, 2011, s. 130. [International Invention Show (silver medal awarded) /36./. Zagreb (HR), 09.11.2011-12.11.2011] Institutional research plan: CEZ:AV0Z40720504 Keywords : aerosol * near real time data * particle distribution Subject RIV: CF - Physical ; Theoretical Chemistry

  7. Use of atmospheric elemental size distributions in estimating aerosol sources in the Helsinki area

    Energy Technology Data Exchange (ETDEWEB)

    Pakkanen, T.A.; Kerminen, V.-M.; Korhonen, C.H.; Hillamo, R.E. [Finnish Meteorological Institute, Helsinki (Finland); Aarnio, P.; Koskentalo, T. [Helsinki Metropolitan Area Council, Helsinki (Finland); Maenhaut, W. [University of Ghent, Gent (Belgium). Institute for Nuclear Sciences

    2001-07-01

    In June 1996-June 1997 Berner impactors were used in the Helsinki area to measure size distribution of atmospheric aerosols simultaneously at an urban and at a rural site. Ten sample pairs were collected in the size range of 0.03-15.7{mu}m of equivalent aerodynamic diameter (EAD). Average size distributions at the two sites were calculated for 29 elements, particulate mass, and sulphate. At both sites especially sulphate, As, B, Cd, Bi, Tl, and V were enriched in fine particles (EAD < 2.3{mu}m). In order to estimate local fine-particle sources of the various chemical components, the similarities and dissimilarities in the accumulation-mode parameters were studied separately for both sites. It was observed that often in different samples, different components had similar accumulation modes. At both sites, particulate mass, As, and Pb had similar accumulation modes to sulphate which suggests that long-range transport (LRT) is important for these components. V, Ni, Mo, and Co formed another group of similar accumulation modes at both sites suggesting that these elements largely originated from local and regional oil combustion. In addition, other groups of similar accumulation modes were observed but these groups were different between the sites. The meteorological parameters indicated that seven sample pairs formed a subset of the data in which the local emissions of the Helsinki area were transported to the urban site but not to the rural site. For this subset the rural fine-particle concentrations were considered to represent an upper limit estimate for the LRT. These upper limit LRT estimations were further improved by utilising the quantitative relative size distributions (QRSD) method at the rural site. The QRSD method supposes that in the fine-particle size range the LRT fractions of all chemical components have a similar shape in their size distributions. Fine-particle sulphate is typically long-range transported, and was therefore selected as the model

  8. Measurements in a highly polluted Asian mega city: observations of aerosol number size distribution, modal parameters and nucleation events

    OpenAIRE

    P. Mönkkönen; I. K. Koponen; K. E. J. Lehtinen; Hämeri, K.; R. Uma; Kulmala, M.

    2005-01-01

    Diurnal variation of number size distribution (particle size 3-800nm) and modal parameters (geometric standard deviation, geometric mean diameter and modal aerosol particle concentration) in a highly polluted urban environment was investigated during October and November 2002 in New Delhi, India. Continuous monitoring for more than two weeks with the time resolution of 10min was conducted using a Differential Mobility Particle Sizer (twin DMPS). The results indicated clear increase in Aitken ...

  9. Measurements in a highly polluted Asian mega city: observations of aerosol number size distribution, modal parameters and nucleation events

    OpenAIRE

    P. Mönkkönen; I. K. Koponen; K. E. J. Lehtinen; Hämeri, K.; R. Uma; Kulmala, M.

    2005-01-01

    Diurnal variation of number size distribution (particle size 3-800nm) and modal parameters (geometric standard deviation, geometric mean diameter and modal aerosol particle concentration) in a highly polluted urban environment was investigated during October and November 2002 in New Delhi, India. Continuous monitoring for more than two weeks with the time resolution of 10min was conducted using a Differential Mobility Particle Sizer (twin DMPS). The results indicated clear i...

  10. Size distributions of aerosol and water-soluble ions in Nanjing during a crop residual burning event

    Institute of Scientific and Technical Information of China (English)

    Honglei Wang; Bin Zhu; Lijuan Shen; Hanqing Kang

    2012-01-01

    To investigate the impact on urban air pollution by crop residual burning outside Nanjing,aerosol concentration,pollution gas concentration,mass concentration,and water-soluble ion size distribution were observed during one event of November 4-9,2010.Results show that the size distribution of aerosol concentration is bimodal on pollution days and normal days,with peak values at 60-70 and 200-300 nm,respectively.Aerosol concentration is 104 cm-3.nm-1 on pollution days.The peak value of spectrum distribution of aerosol concentration on pollution days is 1.5-3.3 times higher than that on a normal day.Crop residual burning has a great impact on the concentration of fine particles.Diurnal variation of aerosol concentration is trimodal on pollution days and normal days,with peak values at 03:00,09:00 and 19:00 local standard time.The first peak is impacted by meteorological elements,while the second and third peaks are due to human activities,such as rush hour traffic.Crop residual burning has the greatest impact on SO2 concentration,followed by NO2,O3 is hardly affected.The impact of crop residual burning on fine particles(< 2.1 μm) is larger than on coarse particles(> 2.1 μm),thus ion concentration in fine particles is higher than that in coarse particles.Crop residual burning leads to similar increase in all ion components,thus it has a small impact on the water-soluble ions order.Crop residual burning has a strong impact on the size distribution of K+,Cl-,Na+,and F- and has a weak impact on the size distributions of NH4+,Ca2+,NO3- and SO42-.

  11. Effect of ejector dilutors on measurements of automotive exhaust gas aerosol size distributions

    International Nuclear Information System (INIS)

    Ejector dilutors have long been used for automotive exhaust particle sampling, as they can offer a low-cost option for stable dilution. In an ejector dilutor, pressurized air expanding in the periphery of a nozzle draws in and mixes with an exhaust sample which is then led to analytical equipment. The combination of processes involved may lead to particle losses which can affect the measurement. This study examines the losses of diesel exhaust particles of different characteristics (nucleation mode, non-volatile accumulation mode, internally and externally mixed accumulation mode) when these are sampled through an ejector dilutor. A scanning mobility particle sizer (SMPS), an electrical low-pressure impactor and a diffusion charger were used as analytical equipment to characterize losses with different instruments. Particle losses were found negligible for all practical applications of diesel exhaust aerosol sampling. Also, the sampling outlet and the operating pressure of the ejector dilutor were found to have a non-measurable effect on the distribution shape. Some variation of the labile nucleation mode particles was attributed to evaporation within the SMPS rather than an ejector effect, and this was confirmed by sampling solid NaCl particles in the same size range. The study further confirms the usability of ejector dilutors for exhaust particle sampling and dilution

  12. Concentration, size-distribution and deposition of mineral aerosol over Chinese desert regions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.Y.; Chen, T.; Zhang, G.Y. [Chinese Academy of Sciences, Xi`an (China). State Key Lab. of Loess and Geology; Arimoto, R. [New Mexico State Univ., Carlsbad, NM (United States). Carlsbad Environmental Monitoring and Research Center; Zhu, G.H. [Beijing Normal Univ., BJ (China). Inst. of Low Energy Nuclear Physics

    1998-09-01

    The mass-particle size distributions (MSDS) of 9 elements in ground-based aerosol samples from dust storm (DS) and non-dust storm (N-DS) periods were determined for 12 sites in 9 major desert regions in northern China. The masses of the 9 elements (Al, Fe, K, Mg, Mn, Se, Si, Sr and Ti) in the atmosphere were dominated by local mineral dust that averaged 270 {mu}g m{sup -3}, and the MSDs for the elements were approximately log-normal. On the basis of Al data, the < 10 {mu}m particles account for {approx} 84% of the total dust mass over the deserts. Model-calculated (`100-step` method) dry deposition velocities (V{sub d}) for the 9 dust-derived elements during N-DS periods ranged from 4.4 to 6.8 cm s{sup -1}, with a median value of 5.6 cm s{sup -1}. On the basis of a statistical relationship between D{sub 99%} (the dust particle diameter corresponding to the uppermost 1% of the cumulative mass distribution) and Vd, one can also predict dry velocities, especially when D{sub 99%} ranges from 30 to 70 {mu}m. This provides a simple way to reconstruct V{sub d} for dust deposits (like aeolian loess sediments in the Loess Plateau). The estimated daily dry deposition fluxes were higher during DS vs. N-DS periods, but in most cases, the monthly averaged fluxes were mainly attributable to N-DS dust. Two regions with high dust loading and fluxes are identified: the Western High-Dust Desert and the Northern High-Dust Desert, with Taklimakan Desert and Badain Juran Desert as their respective centers. These are energetic regions in which desert-air is actively exchanged, and these apparently are the major source areas for Asian dust 32 refs, 4 figs, 5 tabs

  13. Evidence for a bimodal size distribution for the suspended aerosol particles on Mars

    Science.gov (United States)

    Fedorova, A. A.; Montmessin, F.; Rodin, A. V.; Korablev, O. I.; Määttänen, A.; Maltagliati, L.; Bertaux, J.-L.

    2014-03-01

    First simultaneous analysis of the ultraviolet (UV) and infrared (IR) atmospheric extinctions from SPICAM/Mars Express solar occultations in the beginning of the Northern summer (Ls = 56-97°) is presented. The two SPICAM channels allow sounding of the martian atmosphere in the spectral range from 0.118 to 1.7 μm at the altitudes from 10 to 80 km. Based on Mie scattering theory with adequate refraction indices for dust and H2O ice, a bimodal distribution of aerosol has been inferred from the SPICAM measurements. The coarser mode is represented by both dust and H2O particles with average radius of 0.7 and 1.2 μm, respectively, with number density from 0.01 to 10 particles in cm3. Clouds belonging to the aphelion cloud belt have been observed in midlatitudes in the Southern and the Northern hemispheres at altitudes of 20-30 km. The clouds are formed of large particles, and their opacity in the UV and the IR is below 0.03. The finer mode with a radius of 0.04-0.07 μm and a number density from 1 cm-3 at 60 km to 1000 cm-3 at 20 km has been detected in both hemispheres. In the Southern hemisphere the finer mode extends up to 70 km, whereas in the Northern hemisphere it is confined below 30-40 km. The lack of condensation nuclei is consistent, but could not fully explain the high water supersaturation observed between 30 and 50 km in the same Northern hemisphere dataset (Maltagliati L., Montmessin, F., Fedorova, A., Korablev, O., Forget, F., Bertaux, J.-L. [2011]. Science 333, 1868-1871). The average size of the fine mode (∼50 nm) and the large number density (up to 1000 cm-3) most likely corresponds to Aitken particles (r survival of the observed bimodal distribution.

  14. 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

  15. Seasonal and Diurnal Variability of Aerosol Number Size Distribution, Concentration and Gaseous Pollutants in Prague City Center

    Czech Academy of Sciences Publication Activity Database

    Leoni, C.; Kozáková, Jana; Hovorka, J.

    Praha: Czech Aerosol Society, 2015 - (Kubelová, L.), s. 11-14 ISBN 978-80-86186-73-3. [Výroční konference České aerosolové společnosti /16./. Želiv (CZ), 22.10.2015-23.10.2015] R&D Projects: GA ČR(CZ) GBP503/12/G147 Institutional support: RVO:67985858 Keywords : ultrafine particles * aerosol size distribution * urban atmosphere Subject RIV: DN - Health Impact of the Environment Quality http://hdl.handle.net/11104/0251419

  16. Chemical Composition, Seasonal Variation and Size distribution of Atmospheric Aerosols at an Alpine Site in Guanzhong Plain, China

    Science.gov (United States)

    Li, J.

    2015-12-01

    PM10 and size-segregated aerosol samples were collected at Mt. Hua (2065 a.s.m) in central China, and determined for carbonaceous fraction, ions and organic composition. The concentration of most chemical compositions in summer are lower than those in winter, due to decreased emissions of biomass and coal burning for house heating. High temperature and relative humidity (RH) conditions are favorable for secondary aerosol formation, resulting in higher concentrations of SO42- and NH4+ in summer. Non-dehydrated sugars are increased in summer because of the enhanced metabolism. Carbon preference index results indicate that n-alkanes at Mt. Hua are derived mostly by plant wax. Low Benzo(a)pyrene/Benzo(a)pyrene ratios indicate that mountain aerosols are more aged. Concentrations of biogenic (BSOA, the isoprene/pinene/caryophyllene oxidation products) and anthropogenic (ASOA, mainly aromatic acids) SOA positively correlated with temperature . However, a decreasing trend of BSOA concentration with an increase in RH was observed during the sampling period, although a clear trend between ASOA and RH was not found. Based on the AIM Model calculation, we found that during the sampling period an increase in RH resulted in a decrease in the aerosol acidity and thus reduced the effect of acid-catalysis on BSOA formation. Size distributions of K+ and NH4+ present as an accumulation mode, in contrast to Ca2+ and Mg2+, which are mainly existed in coarse particles. SO42- and NO3- show a bimodal pattern. Dehydrated sugars, fossil fuel derived n-alkanes and PAHs presented unimode size distribution, whereas non-dehydrated sugars and plant wax derived n-alkanes showed bimodal pattern. Most of the determined BSOA are formed in the aerosol phase and enriched in the fine mode except for cis-pinonic acid, which is formed in the gas phase and subsequently partitioned into aerosol phase and thus presents a bimodal pattern with a major peak in the coarse mode.

  17. Study of real time detection and size distribution measurement of ultrafine aerosol with a particle growth system (PGS)

    Energy Technology Data Exchange (ETDEWEB)

    Rebours, A.

    1994-06-29

    First, the theoretical knowledge on condensation phenomena of a supersaturated vapor in a cylindrical duct where an ultrafine aerosol of nanometers size is flowing, is recalled. Then, a Particle Growth-System (PGS) of original design is developed: the aerosol is confined in a region with a uniform vapor supersaturation profile. When imperfectly filtered atmospheric air is used as source of condensation nuclei, the produced droplets are found to be monodisperse. Therefore, our PGS offers a simple method of calibrating Optical Particle Counters because the size distribution of theses droplets is controlled. After an experimental study validated by a theoretical model, we establish that, under certain supersaturation conditions, the droplet size in our PGS is a function of ultrafine particle size on which the vapor condenses. Furthermore, when the sampled aerosol is constituted of an ultrafine fraction and a fine fraction, we show that the size distribution of the droplets that come out from the PGS is bimodal too. Finally, a simple redesign of our fluids inlet system should reduce particles losses in the PGS due to brownian diffusion and, in that manner improve their detection. (author). 72 refs., 46 figs., 8 tabs., 4 appends.

  18. Particle size distribution and inorganic aerosol characterization during DAURE 2009 winter field campaign at Montseny site

    Science.gov (United States)

    Aranzazu Revuelta, M.; Gómez-Moreno, Francisco J.; Plaza, Javier; Coz, Esther; Pey, Jorge; Cusack, Michael; Pandolfi, Marco; Rodríguez-Maroto, Jesús J.; Pujadas, Manuel

    2010-05-01

    During DAURE 2009 winter field campaign, one of the sampling sites was Montseny, a rural background station located 40 km NNE from Barcelona and 25 km W from the Mediterranean Sea. It is a Natural Park and a protected area, thus with low human activity, mainly agriculture. The sampling station was located on a valley with it axis oriented on the direction NW-SE. At this site, a TSI-SMPS (DMA 3071 and CPC 3022) was installed in order to measure the particle number distribution in the size range 15-600 nm during the period March 19-27 with a measurement cycle of 12 minutes The particle mass distribution was measured by a micro-orifice uniform deposit impactor (MOUDI) using eleven size stages with aluminum substrates and a quartz fiber backup filter. Four samples were taken during the period 13-19 March, two during 24 hours and other two during 48 hours. This impactor has a wider size range allowing to measure from 56 to 18000 nm. The substrates and filters obtained were later analyzed for determining soluble ions (sulfate, nitrate, ammonium and calcium) by IC. There are mainly two different kinds of events measured with the SMPS. When the air masses were coming from SE, which meant that they could come from the park but also from the urban and industrial areas located in the pre-coastal depression, it was characterized by higher particle number concentrations and by size distributions centered on 80 nm. This meant it was an aged aerosol, which had grown up by coagulation, condensation and oxidation processes. When the air masses were coming from NW (the second valley axis side), the particle measured were much smaller, the instrument started to detect particles with 15 nm, but smaller ones could be possible. This meant that new particle nucleation could have occurred in the valley, just before arriving to the sampling point. From MOUDI samplings, two different types of events were also observed. Three of the four samplings coincided with stagnation of air masses or

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

    International Nuclear Information System (INIS)

    With a view to studying the natural radioactive particles produced by atttachment of 222Rn 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 222Rn 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

  20. Black carbon mass size distributions of diesel exhaust and urban aerosols measured using differential mobility analyzer in tandem with Aethalometer

    OpenAIRE

    Chan, K. L.; Wong, K. C.; Westerdahl, Dane; Cheung, C. S.; Močnik, Griša; Ning, Zhi; Zhou, J. H.

    2015-01-01

    Black carbon (BC) is the dominant component of the light absorbing aerosols in the atmosphere, changing earthʼs radiative balance and affecting the climate. The mixing state and size distribution of atmospheric BC are largely unknown and cause uncertainties in climate models. BC is also a major component of diesel PM emissions, recently classified by World Health Organization as Category I Carcinogen, and has been associated with various adverse health effects. This study presents a novel app...

  1. Size distribution, mixing state and source apportionments of black carbon aerosols in London during winter time

    Directory of Open Access Journals (Sweden)

    D. Liu

    2014-06-01

    Dc distributions and coating thicknesses, with BCsf displaying larger Dc and larger coating thickness compared to BCtr. BC particles from different sources were also apportioned by applying a multiple linear regression between the total BC mass and each AMS-PMF factor (BC-AMS-PMF method, and also attributed by applying the absorption spectral dependence of carbonaceous aerosols to 7-wavelength Aethalometer measurements (Aethalometer method. Air masses that originated from westerly (W, southeasterly (SE, or easterly (E sectors showed BCsf fractions that ranged from low to high, and whose mass median Dc values were 137 ± 10 nm, 143 ± 11 nm, and 169 ± 29 nm respectively. The corresponding bulk relative coating thickness of BC (coated particle size / BC core – Dp / Dc for these same sectors was 1.28 ± 0.07, 1.45 ± 0.16, and 1.65 ± 0.19. For W, SE and E air masses, the number fraction of BCsf ranged from 6 ± 2% to 11 ± 5% to 18 ± 10% respectively, but importantly the larger BC core sizes lead to an increased fraction of BCsf in terms of mass than number (for W–SE–E air masses, the BCsf mass fractions ranged from 16 ± 6 %–24 ± 10%–39 ± 14% respectively. An increased fraction of non-BC particles (particles that did not contain a BC core was also observed when SF sources were more significant. The BC mass attribution by the SP2 method agreed well with the BC-AMS-PMF multiple linear regression method (BC-AMS-PMF : SP2 ratio = 1.05, r2 = 0.80 over the entire experimental period. Good agreement was found between BCsf attributed with the Aethalometer model and the SP2. However, the assumed Absorption Ångström Exponent (αwb had to be changed according to the different air mass sectors to yield the best comparison with the SP2. This could be due to influences of fuel type or burn phase.

  2. Black carbon mass size distributions of diesel exhaust and urban aerosols measured using differential mobility analyzer in tandem with Aethalometer

    Science.gov (United States)

    Ning, Zhi; Chan, K. L.; Wong, K. C.; Westerdahl, Dane; Močnik, Griša; Zhou, J. H.; Cheung, C. S.

    2013-12-01

    Black carbon (BC) is the dominant component of the light absorbing aerosols in the atmosphere, changing earth's radiative balance and affecting the climate. The mixing state and size distribution of atmospheric BC are largely unknown and cause uncertainties in climate models. BC is also a major component of diesel PM emissions, recently classified by World Health Organization as Category I Carcinogen, and has been associated with various adverse health effects. This study presents a novel approach of direct and continuous measurement of BC mass size distribution by tandem operation of a differential mobility spectrometry and a refined Aethalometer. A condensation particle counter was deployed in parallel with the Aethalometer to determine particle number size distribution. A wide range of particle sizes (20-600 nm) was investigated to determine the BC modal characteristics in fresh diesel engine tailpipe emissions and in different urban environments including a typical urban ambient site and a busy roadside. The study provided a demonstration of a new analytic approach and showed the evolution of BC mass size distribution from fresh engine emissions to the aged aerosols in the roadside and ambient environments. The results potentially can be used to refine the input for climate modeling to determine the effect of particle-bound atmospheric BC on the global climate.

  3. Arctic aerosol life cycle: linking aerosol size distributions observed between 2000 and 2010 with air mass transport and precipitation at Zeppelin station, Ny-Ålesund, Svalbard

    Directory of Open Access Journals (Sweden)

    P. Tunved

    2012-11-01

    Full Text Available In this study we present a qualitative and quantitative assessment of more the 10 yr of aerosol number size distribution data observed in the Arctic environment (Mt Zeppelin (78°56' N, 11°53' E, 474 m a.s.l., Ny Ålesund, Svalbard. We provide statistics on both seasonal and diurnal characteristics of the aerosol observations and conclude that the Arctic aerosol number size distribution and auxiliary parameters such as integral mass and surface have a very pronounced seasonal variation. This seasonal variation seems to be controlled by both dominating source as well as meteorological conditions in general. In principle, three distinctly different periods can be identified during the Arctic year: the haze period characterized by a dominating accumulation mode aerosol (March–May followed by the sunlit summer period with low abundance of accumulation mode particles but high concentration of small particles which likely are recently and locally formed (June–August. The rest of the year is characterized by comparably low concentration of accumulation mode particles and negligible abundance of ultra fine particles (September–February. Minimum aerosol mass and number concentration is usually observed during September/October. We further show that the transition between the different regimes is fast, suggesting rapid change in conditions defining their appearance. A source climatology based on trajectory analysis is provided and it is shown that there is a strong seasonality of dominating source areas, with dominance of Eurasia during the autumn-winter period and dominance of North Atlantic air during the summer months. We also show that new particle formation events seem to be a rather common phenomenon during the Arctic summer, and this is the result of both photochemical production of nucleating/condensing species and low condensation sink. It is also suggested that wet removal play a key role in defining the Arctic aerosol year, and plays a

  4. Non-supervised Classification of Ground-based Radiometer Retrievals in Order to Assess the Natural Distribution of Aerosol Volume Size Distributions and Refractive Indexes

    Science.gov (United States)

    Gross, L.; Frouin, R.; Pietras, C.; Knobelspiesse, K.; Fargion, G.

    2002-05-01

    . The AERONET and SIMBIOS Projects have invested considerable effort to deploy and maintain the instruments to ensure the quality of the data for more than 4 years. The maturity of the CIMEL data processing procedures and inversion algorithms (Dubovik and King, 2000), allows us to make a global statistic on aerosols mixtures. A non-supervised classification of the retrieved aerosol properties of the total atmospheric column, i.e. the volume size distribution function and the refractive index, may allow us to determine their natural distribution and more importantly to identify clusters in this distribution. These clusters may be used as new aerosol mixtures in radiative transfer algorithms. We show here a first attempt of classification, using a basic self-organizing map (Kohonen, 1984) to approximate the distribution of the data, followed by a hierarchical clustering to identify the more encountered geophysical conditions in the data base.

  5. The Influence of Wildfires on Aerosol Size Distributions in Rural Areas

    OpenAIRE

    Alonso-Blanco, E.; Calvo, A. I.; R. Fraile; Castro, A

    2012-01-01

    The number of particles and their size distributions were measured in a rural area, during the summer, using a PCASP-X. The aim was to study the influence of wildfires on particle size distributions. The comparative studies carried out reveal an average increase of around ten times in the number of particles in the fine mode, especially in sizes between 0.10 and 0.14  μ m, where the increase is of nearly 20 times. An analysis carried out at three different points in time—before, during, and a...

  6. 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

  7. Particle size distribution of aerosols during sand-blasting of steam turbines

    International Nuclear Information System (INIS)

    Studies were performed to determine the activity median aerodynamic diameter and the solubility classification of radioactive airborne particulates produced during sand blasting of steam turbines at Chin Shan Nuclear Power Station in Taiwan. Cascade impactors were used to collect air samples in the sand blasting house for analyses of particle size and elemental composition. Radionuclides identified in the samples included 60Co, 137Cs, 131I, 140Ba, 140La and 141Ce. These were found to have an activity median aerodynamic diameter of 3 μm to 4 μm, except for volatile 131I, which had a somewhat smaller diameter of 2.8 μm. The major elements composing the aerosols were Si, Fe, Ca, K, Al, and Cr. (author)

  8. In situ measurements of aerosols optical properties and number size distributions in a subarctic coastal region of Norway

    Directory of Open Access Journals (Sweden)

    S. Mogo

    2011-12-01

    Full Text Available In situ measurements of aerosol optical properties were made in the summer of 2008 at the ALOMAR station facility (69°16 N, 16°00 E, located at a rural site in the north of the island of Andøya (Vesterålen archipelago, approximately 300 km north of the Arctic Circle. The extended three-month campaign was part of the POLARCAT Project (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols, and Transport of the International Polar Year (IPY-2007-2008. Its goal was to characterize the aerosols of this sub-Arctic area, which are frequently transported to the Arctic region. The ambient light-scattering coefficient, σs (550 nm, at ALOMAR had a measured hourly mean value of 5.41 Mm−1 (StD = 3.55 Mm−1, and the light-absorption coefficient, σa (550 nm, had a measured hourly mean value of 0.40 Mm−1 (StD = 0.27 Mm−1. The scattering/absorption Ångström exponents, αs,a, are used for a detailed analysis of the variations of the spectral shape of σs,a. Whereas αs demonstrates the presence of two particle sizes corresponding to two types of aerosols, the αa demonstrates only one type of absorbing aerosol particles. Values of αa above 1 were not observed. The single-scattering albedo, ω0, ranged from 0.62 to 0.99 (mean = 0.91, StD = 0.05, and the relationships of this property to the absorption/scattering coefficients and the Ångström exponents are presented. The concentration of the particles was monitored using a scanning mobility particle sizer (SMPS, an aerodynamic particle sizer (APS and an ultrafine condensation particle counter (UCPC. The shape of the median size distribution of the particles in the submicrometer fraction was bimodal, and the submicrometer, micrometer and total concentrations presented hourly mean values of 1277 cm3 (St

  9. Size distributions of mineral aerosols and dust emission flux observed over Horqin Sandy Land area in northern China

    Science.gov (United States)

    Li, X.; Zhang, H. S.

    2013-01-01

    Size distribution of mineral aerosols is of primary importance in determining their residence time in atmosphere, transport patterns, removal mechanisms as well as their effects on climate and human health. This study aims to obtain dust particle size distribution and size-resolved dust emission flux under different weather conditions over a sandy land area in northern China (Horqin Sandy Land, Inner Mongolia), using the observational data from Horqin sandstorm monitoring station in the spring of 2010 and 2012. Dust (PM20) mass concentration was measured by a 10-stage quartz crystal microbalance (QCM) cascade impactor. The statistical results indicate that finer dust particles (r ≤ 1.0 μm) take a large proportion of all PM20 concentration under clear-day conditions, while coarser dust particles (r ≥ 2.5 μm) concentration increased under dust-day conditions, with the peak occurring between 4-7 μm. The dust particle size distributions during the pre-dust-emission and dust-emission periods of a dust event on 7 April 2012 have similar features to the statistical results. During the dust event, the magnitude of dust emission flux of all sizes increased about one or two orders (0.1-10 μg m-2 s-1) as u* increase from 0.54 to 1.29 m s-1. The maximum total F value was about 43.0 μg m-2 s-1 and the maximum size-resolved F(Ddi) is 12.3 μg m-2 s-1 in 0.3-0.45 μm size bin when u* is 1.29 m s-1. Dust advection has effects on airborne dust size distribution, making the proportion of dust particles of different sizes more uniform, as observed in a non-local dust event on 19 April 2012.

  10. Long-term observations of aerosol size distributions in semi-clean and polluted savannah in South Africa

    Science.gov (United States)

    Vakkari, V.; Beukes, J. P.; Laakso, H.; Mabaso, D.; Pienaar, J. J.; Kulmala, M.; Laakso, L.

    2013-02-01

    This study presents a total of four years of sub-micron aerosol particle size distribution measurements in the southern African savannah, an environment with few previous observations covering a full seasonal cycle and the size range below 100 nm. During the first 19 months, July 2006-January 2008, the measurements were carried out at Botsalano, a semi-clean location, whereas during the latter part, February 2008-May 2010, the measurements were carried out at Marikana (approximately 150 km east of Botsalano), which is a more polluted location with both pyrometallurgical industries and informal settlements nearby. The median total concentration of aerosol particles was more than four times as high at Marikana than at Botsalano. In the size ranges of 12-840 nm, 50-840 nm and 100-840 nm the median concentrations were 1856, 1278 and 698 particles cm-3 at Botsalano and 7805, 3843 and 1634 particles cm-3 at Marikana, respectively. The diurnal variation of the size distribution for Botsalano arose as a result of frequent regional new particle formation. However, for Marikana the diurnal variation was dominated by the morning and evening household burning in the informal settlements, although regional new particle formation was even more frequent than at Botsalano. The effect of the industrial emissions was not discernible in the size distribution at Marikana although it was clear in the sulphur dioxide diurnal pattern, indicating the emissions to be mostly gaseous. Seasonal variation was strongest in the concentration of particles larger than 100 nm, which was clearly elevated at both locations during the dry season from May to September. In the absence of wet removal during the dry season, the concentration of particles larger than 100 nm had a correlation above 0.7 with CO for both locations, which implies incomplete burning to be an important source of aerosol particles during the dry season. However, the sources of burning differ: at Botsalano the rise in

  11. Long-term observations of aerosol size distributions in semi-clean and polluted savannah in South Africa

    Directory of Open Access Journals (Sweden)

    V. Vakkari

    2013-02-01

    Full Text Available This study presents a total of four years of sub-micron aerosol particle size distribution measurements in the southern African savannah, an environment with few previous observations covering a full seasonal cycle and the size range below 100 nm. During the first 19 months, July 2006–January 2008, the measurements were carried out at Botsalano, a semi-clean location, whereas during the latter part, February 2008–May 2010, the measurements were carried out at Marikana (approximately 150 km east of Botsalano, which is a more polluted location with both pyrometallurgical industries and informal settlements nearby.

    The median total concentration of aerosol particles was more than four times as high at Marikana than at Botsalano. In the size ranges of 12–840 nm, 50–840 nm and 100–840 nm the median concentrations were 1856, 1278 and 698 particles cm−3 at Botsalano and 7805, 3843 and 1634 particles cm−3 at Marikana, respectively.

    The diurnal variation of the size distribution for Botsalano arose as a result of frequent regional new particle formation. However, for Marikana the diurnal variation was dominated by the morning and evening household burning in the informal settlements, although regional new particle formation was even more frequent than at Botsalano. The effect of the industrial emissions was not discernible in the size distribution at Marikana although it was clear in the sulphur dioxide diurnal pattern, indicating the emissions to be mostly gaseous.

    Seasonal variation was strongest in the concentration of particles larger than 100 nm, which was clearly elevated at both locations during the dry season from May to September. In the absence of wet removal during the dry season, the concentration of particles larger than 100 nm had a correlation above 0.7 with CO for both locations, which implies incomplete burning to be an important source of aerosol particles during the dry

  12. Long-term observations of aerosol size distributions in semi-clean and polluted savannah in South Africa

    Directory of Open Access Journals (Sweden)

    V. Vakkari

    2012-09-01

    Full Text Available This study presents a total of four years of sub-micron aerosol particle size distribution measurements in the Southern African savannah, an environment with few previous observations covering a full seasonal cycle and the size range below 100 nm. During the first 19 months, July 2006–January 2008, the measurements were carried out at Botsalano, a semi-clean location, whereas during the latter part, February 2008–May 2010, the measurements were carried out at Marikana (approximately 150 km east of Botsalano, which is a more polluted location with both pyrometallurgical industries and informal settlements nearby.

    The median total concentration of aerosol particles was more than four times as high at Marikana than at Botsalano. In the size ranges of 12–840 nm, 50–840 nm and 100–840 nm the median concentrations were 1850, 1280 and 700 particles cm−3 at Botsalano and 7800, 3800 and 1600 particles cm−3 at Marikana, respectively.

    The diurnal variation of the size distribution for Botsalano arose as a result of frequent regional new particle formation. However, for Marikana the diurnal variation was dominated by the morning and evening household burning in the informal settlements, although regional new particle formation was even more frequent than at Botsalano. The effect of the industrial emissions was not discernible in the size distribution at Marikana although it was clear in the sulphur dioxide diurnal pattern, indicating the emissions to be mostly gaseous.

    Seasonal variation was strongest in the concentration of particles larger than 100 nm, which was clearly elevated at both locations during the dry season from May to September. In the absence of wet removal during the dry season the concentration of particles larger than 100 nm had a correlation above 0.7 with CO for both locations, which implies incomplete burning to be an important source of aerosol particles during the dry

  13. Universal spectrum for atmospheric aerosol size distribution: comparison with pcasp-b observations of vocals 2008

    CERN Document Server

    Selvam, A M

    2011-01-01

    Atmospheric flows exhibit self-similar fractal space-time fluctuations on all space-time scales in association with inverse power law distribution for power spectra of meteorological parameters such as wind, temperature, etc., and thus implies long-range correlations, identified as self-organized criticality generic to dynamical systems in nature. A general systems theory developed by the author visualizes the fractal fluctuations to result from the coexistence of eddy fluctuations in an eddy continuum, the larger scale eddies being the integrated mean of enclosed smaller scale eddies. The model predicts that the probability distributions of component eddy amplitudes and the corresponding variances (power spectra) are quantified by the same universal inverse power law distribution incorporating the golden mean. Atmospheric particulates are held in suspension by the vertical velocity distribution spectrum. The atmospheric particulate size spectrum is derived in terms of the model predicted universal inverse po...

  14. The mathematical principles and design of the NAIS - a spectrometer for the measurement of cluster ion and nanometer aerosol size distributions

    Science.gov (United States)

    Mirme, S.; Mirme, A.

    2013-04-01

    The paper describes the Neutral cluster and Air Ion Spectrometer (NAIS) - a multichannel aerosol instrument capable of measuring the distribution of ions (charged particles and cluster ions) of both polarities in the electric mobility range from 3.2 to 0.0013 cm2 V-1 s-1 and the distribution of aerosol particles in the size range from 2.0 to 40 nm. We introduce the principles of design, data processing and spectrum deconvolution of the instrument.

  15. Urban aerosol size distributions over the Mediterranean city of Barcelona, NE Spain

    OpenAIRE

    Dall'Osto, M.; Beddows, D.C.S.; J. Pey; Rodriguez, S.; A. Alastuey; R. M. Harrison; X. Querol

    2012-01-01

    Differential mobility particle sizer (DMPS) aerosol concentrations (N13–800) were collected over a one-year-period (2004) at an urban background site in Barcelona, North-Eastern Spain. Quantitative contributions to particle number concentrations of the nucleation (33–38%), Aitken (39–49%) and accumulation mode (18–22%) were estimated. We examined the source and time variability of atmospheric aerosol particles by using both K-means clus...

  16. Urban aerosol size distributions over the Mediterranean city of Barcelona, NE Spain

    OpenAIRE

    Dall'Osto, M.; Beddows, D.C.S.; J. Pey; Rodriguez, S.; A. Alastuey; Harrison, Roy M; X. Querol

    2012-01-01

    Differential mobility particle sizer (DMPS) aerosol concentrations (N13-800) were collected over a one-year-period (2004) at an urban background site in Barcelona, North-Eastern Spain. Quantitative contributions to particle number concentrations of the nucleation (33–39%), Aitken (39–49%) and accumulation mode (18–22%) were estimated. We examined the source and time variability of atmospheric aerosol particles by using both K-means clustering and Positive Matrix Factori...

  17. Particle size distribution of workplace aerosols in manganese alloy smelters applying a personal sampling strategy.

    Science.gov (United States)

    Berlinger, B; Bugge, M D; Ulvestad, B; Kjuus, H; Kandler, K; Ellingsen, D G

    2015-12-01

    Air samples were collected by personal sampling with five stage Sioutas cascade impactors and respirable cyclones in parallel among tappers and crane operators in two manganese (Mn) alloy smelters in Norway to investigate PM fractions. The mass concentrations of PM collected by using the impactors and the respirable cyclones were critically evaluated by comparing the results of the parallel measurements. The geometric mean (GM) mass concentrations of the respirable fraction and the <10 μm PM fraction were 0.18 and 0.39 mg m(-3), respectively. Particle size distributions were determined using the impactor data in the range from 0 to 10 μm and by stationary measurements by using a scanning mobility particle sizer in the range from 10 to 487 nm. On average 50% of the particulate mass in the Mn alloy smelters was in the range from 2.5 to 10 μm, while the rest was distributed between the lower stages of the impactors. On average 15% of the particulate mass was found in the <0.25 μm PM fraction. The comparisons of the different PM fraction mass concentrations related to different work tasks or different workplaces, showed in many cases statistically significant differences, however, the particle size distribution of PM in the fraction <10 μm d(ae) was independent of the plant, furnace or work task. PMID:26498986

  18. Aerosol particle number size distributions and particulate light absorption at the ZOTTO tall tower (Siberia), 2006-2009

    Science.gov (United States)

    Heintzenberg, J.; Birmili, W.; Otto, R.; Andreae, M. O.; Mayer, J.-C.; Chi, X.; Panov, A.

    2011-08-01

    This paper analyses aerosol particle number size distributions, particulate absorption at 570 nm wavelength and carbon monoxide (CO) measured between September 2006 and January 2010 at heights of 50 and 300 m at the Zotino Tall Tower Facility (ZOTTO) in Siberia (60.8° N; 89.35° E). Average number, surface and volume concentrations are broadly comparable to former studies covering shorter observation periods. Fits of multiple lognormal distributions yielded three maxima in probability distribution of geometric mean diameters in the Aitken and accumulation size range and a possible secondary maximum in the nucleation size range below 25 nm. The seasonal cycle of particulate absorption shows maximum concentrations in high winter (December) and minimum concentrations in mid-summer (July). The 90th percentile, however, indicates a secondary maximum in July/August that is likely related to forest fires. The strongly combustion derived CO shows a single winter maximum and a late summer minimum, albeit with a considerably smaller seasonal swing than the particle data due to its longer atmospheric lifetime. Total volume and even more so total number show a more complex seasonal variation with maxima in winter, spring, and summer. A cluster analysis of back trajectories and vertical profiles of the pseudo-potential temperature yielded ten clusters with three levels of particle number concentration: Low concentrations in Arctic air masses (400-500 cm-3), mid-level concentrations for zonally advected air masses from westerly directions between 55° and 65° N (600-800 cm-3), and high concentrations for air masses advected from the belt of industrial and population centers in Siberia and Kazakhstan (1200 cm-3). The observational data is representative for large parts of the troposphere over Siberia and might be particularly useful for the validation of global aerosol transport models.

  19. The mathematical principles and design of the NAIS – a spectrometer for the measurement of cluster ion and nanometer aerosol size distributions

    Directory of Open Access Journals (Sweden)

    S. Mirme

    2011-12-01

    Full Text Available The paper describes the Nanometer aerosol and Air Ion Spectrometer (NAIS – a multi-channel aerosol instrument capable of measuring the distribution of ions (charged particles and cluster ions of both polarities in the electric mobility range from 3.2 to 0.0013 cm2 V−1 s−1 and the distribution of aerosol particles in the size range from 2.0 to 40 nm. We introduce the principles of design, data processing and spectrum deconvolution of the instrument.

  20. Chemical composition and aerosol size distribution of the middle mountain range in the Nepal Himalayas during the 2009 pre-monsoon season

    Directory of Open Access Journals (Sweden)

    P. Shrestha

    2010-06-01

    Full Text Available Aerosol particle number size distribution and chemical composition were measured at two low altitude sites, one urban and one relatively pristine valley, in Central Nepal during the 2009 pre-monsoon season (May–June. This is the first time that aerosol size distribution and chemical composition were measured simultaneously at lower elevation in the Middle Himalayan region in Nepal. The aerosol size distribution was measured using a Scanning Mobility Particle Sizer (SMPS, 14~340 nm, and the chemical composition of the filter samples collected during the field campaign was analyzed in the laboratory. Teflon membrane filters were used for ion chromatography (IC and water-soluble organic carbon and nitrogen analysis. Quartz fiber filters were used for organic carbon and elemental carbon analysis. Multi-lognormal fits to the measured aerosol size distribution indicated a consistent larger mode around 100 nm which is usually the oldest, most processed background aerosol. The smaller mode was located around 20 nm, which is indicative of fresh but not necessarily local aerosol. The diurnal cycle of the aerosol number concentration showed the presence of two peaks (early morning and evening, during the transitional period of boundary layer growth and collapse. The increase in number concentration during the peak period was observed for the entire size distribution. Although the possible contribution of local emissions in size ranges similar to the larger mode cannot be completely ruled out, another plausible explanation is the mixing of aged elevated aerosol in the residual layer during the morning period as suggested by previous studies. Similarly, the evening time concentration peaks when the boundary layer becomes shallow concurrent with increase in local activity. A decrease in aerosol number concentration was observed during the nighttime with the development of cold (downslope mountain winds that force the low level warmer air in the valley to

  1. Size distribution of heavy metal aerosols in cooling and spray dryer system

    Energy Technology Data Exchange (ETDEWEB)

    Wey, M.Y.; Yang, J.T.; Peng, C.Y.; Chiang, B.C.

    1999-11-01

    The cooling process prior to treating flue gas and the spray dryer process that removes acid components in flue gas are believed to influence the mass and elemental size distributions of heavy metal in fly ash. The main objective of this study was to investigate the effects of operating parameters on the mass and elemental size distributions of heavy metals in fly ash produced from a fluidized bed incineration and a water cooling or spray dryer flue gas treatment system. The operating parameters investigated included (1) the controlling temperature in the gas cooling system; (2) the controlling temperature in the spray dryer system; (3) the addition of organic chlorides; and (4) the addition of inorganic chloride. The experimental results indicated that the water cooling process and spray dryer process increase the amount of coarse fly ash and increase the total concentration of metal in fly ash. The amounts of fine fly ash and the total concentration of metal in fine fly ash increase with decreasing temperature during the water cooling process. However, the amounts of fine fly ash and the total concentration of metal in fine fly ash decrease with decreasing temperature during the spray dryer process.

  2. Activity size distributions for long-lived radon decay products in aerosols collected in Barcelona (Spain)

    International Nuclear Information System (INIS)

    The activity median aerodynamic diameters (AMADs) of long-lived radon decay product (210Pb, 210Po) in aerosols collected in the Barcelona area (Northeast Spain) during the period from April 2006 to February 2008 are presented. The 210Po mean AMAD was 420 nm, while the 210Pb mean AMAD was 500 nm. The temporal evolution of 210Pb and 210Po AMADs shows maxima in autumn and winter and minima in spring and summer. 210Pb AMAD are being used to estimate the mean-residence time of atmospheric aerosols.

  3. 6.7 Continuous Aerosol Number Size Distributions Measurement at Košetice Observatory

    Czech Academy of Sciences Publication Activity Database

    Zíková, Naděžda; Ondráček, Jakub; Schwarz, Jaroslav; Ždímal, Vladimír

    Vol. 1. Prague : Czech Hydrometeorological Institute, 2014 - (Holubová Šmejkalová, A.), s. 69-73 ISBN 978-80-87577-40-0 R&D Projects: GA ČR GAP209/11/1342 Institutional support: RVO:67985858 Keywords : atmospheric aerosols * backround station * monitoring Subject RIV: CF - Physic al ; Theoretical Chemistry http://hdl.handle.net/11104/0245199

  4. Scale-free Universal Spectrum for Atmospheric Aerosol Size Distribution for Davos, Mauna Loa and Izana

    CERN Document Server

    Selvam, A M

    2011-01-01

    Atmospheric flows exhibit fractal fluctuations and inverse power law form for power spectra indicating an eddy continuum structure for the selfsimilar fluctuations. A general systems theory for fractal fluctuations developed by the author is based on the simple visualisation that large eddies form by space-time integration of enclosed turbulent eddies, a concept analogous to Kinetic Theory of Gases in Classical Statistical Physics. The ordered growth of atmospheric eddy continuum is in dynamical equilibrium and is associated with Maximum Entropy Production. The model predicts universal (scale-free) inverse power law form for fractal fluctuations expressed in terms of the golden mean. Atmospheric particulates are held in suspension in the fractal fluctuations of vertical wind velocity. The mass or radius (size) distribution for homogeneous suspended atmospheric particulates is expressed as a universal scale-independent function of the golden mean, the total number concentration and the mean volume radius. Mode...

  5. Transient variation of aerosol size distribution in an underground subway station.

    Science.gov (United States)

    Kwon, Soon-Bark; Namgung, Hyeong-Gyu; Jeong, Wootae; Park, Duckshin; Eom, Jin Ki

    2016-06-01

    As the number of people using rapid transit systems (subways) continues to rise in major cities worldwide, increasing attention has been given to the indoor air quality of underground stations. This study intended to observe the change of PM distribution by size in an underground station with PSDs installed located near the main road in downtown Seoul, as well as to examine causes for the changes. The results indicate that the PM suspended in the tunnel flowed into the platform area even in a subway station where the effect of train-induced wind is blocked by installed PSDs, as this flow occurred when the PSDs were opened. The results also indicate that coarse mode particles generated by mechanical friction in the tunnel, such as that between wheels and rail, also flowed into the platform area. The PM either settled or was re-suspended according to size and whether the ventilation in the platform area was in operation or if the platform floor had been washed. The ventilation system was more effective in removing PM of smaller sizes (fine particles) while the wash-out performed after train operations had stopped reduced the suspension of coarse mode particles the next morning. Despite installation of the completely sealed PSDs, inflow of coarse mode particles from the tunnel seems unavoidable, indicating the need for measures to decrease the PM generated there to lower subway user exposure since those particles cannot be reduced by mechanical ventilation alone. This research implicate that coarse PM containing heavy metals (generated from tunnel side) proliferated especially during rush hours, during which it is very important to control those PM in order to reduce subway user exposure to this hazardous PM. PMID:27220501

  6. Size distributions of mineral aerosols and dust emission flux observed over Horqin Sandy Land area in northern China

    Directory of Open Access Journals (Sweden)

    X. Li

    2013-01-01

    Full Text Available Size distribution of mineral aerosols is of primary importance in determining their residence time in atmosphere, transport patterns, removal mechanisms as well as their effects on climate and human health. This study aims to obtain dust particle size distribution and size-resolved dust emission flux under different weather conditions over a sandy land area in northern China (Horqin Sandy Land, Inner Mongolia, using the observational data from Horqin sandstorm monitoring station in the spring of 2010 and 2012. Dust (PM20 mass concentration was measured by a 10-stage quartz crystal microbalance (QCM cascade impactor. The statistical results indicate that finer dust particles (r ≤ 1.0 μm take a large proportion of all PM20 concentration under clear-day conditions, while coarser dust particles (r ≥ 2.5 μm concentration increased under dust-day conditions, with the peak occurring between 4–7 μm. The dust particle size distributions during the pre-dust-emission and dust-emission periods of a dust event on 7 April 2012 have similar features to the statistical results. During the dust event, the magnitude of dust emission flux of all sizes increased about one or two orders (0.1–10 μg m−2 s−1 as u* increase from 0.54 to 1.29 m s−1. The maximum total F value was about 43.0 μg m−2 s−1 and the maximum size-resolved F(Ddi is 12.3 μg m−2 s−1 in 0.3–0.45 μm size bin when u* is 1.29 m s−1. Dust advection has effects on airborne dust size distribution, making the proportion of dust particles of different sizes more uniform, as observed in a non-local dust event on 19 April 2012.

  7. Size distributions of nano/micron dicarboxylic acids and inorganic ions in suburban PM episode and non-episodic aerosol

    Science.gov (United States)

    Hsieh, Li-Ying; Kuo, Su-Ching; Chen, Chien-Lung; Tsai, Ying I.

    The distribution of nano/micron dicarboxylic acids and inorganic ions in size-segregated suburban aerosol of southern Taiwan was studied for a PM episode and a non-episodic pollution period, revealing for the first time the distribution of these nanoscale particles in suburban aerosols. Inorganic species, especially nitrate, were present in higher concentrations during the PM episode. A combination of gas-to-nuclei conversion of nitrate particles and accumulation of secondary photochemical products originating from traffic-related emissions was likely a crucial cause of the PM episode. Sulfate, ammonium, and oxalic acid were the dominant anion, cation, and dicarboxylic acid, respectively, accounting for a minimum of 49% of the total anion, cation or dicarboxylic acid mass. Peak concentrations of these species occurred at 0.54 μm in the droplet mode during both non-episodic and PM episode periods, indicating an association with cloud-processed particles. On average, sulfate concentration was 16-17 times that of oxalic acid. Oxalic acid was nevertheless the most abundant dicarboxylic acid during both periods, followed by succinic, malonic, maleic, malic and tartaric acid. The mass median aerodynamic diameter (MMAD) of oxalic acid was 0.77 μm with a bi-modal presence at 0.54 μm and 18 nm during non-episodic pollution and an MMAD of 0.67 μm with mono-modal presence at 0.54 μm in PM episode aerosol. The concomitant formation of malonic acid and oxalic acid was attributed to in-cloud processes. During the PM episode in the 5-100 nm nanoscale range, an oxalic acid/sulfate mass ratio of 40.2-82.3% suggested a stronger formation potential for oxalic acid than for sulfate in the nuclei mode. For total cations (TC), total inorganic anions (TIA) and total dicarboxylic acids (TDA), major contributing particles were in the droplet mode, with least in the nuclei mode. The ratio of TDA to TIA in the nuclei mode increased greatly from 8.40% during the non-episodic pollution

  8. Production Mechanisms, Number Concentration, Size Distribution. Chemical Composition, and Optical Properties of Sea Spray Aerosols

    Science.gov (United States)

    Meskhidze, Nicholas; Petters, Markus; Tsigaridis, Kostas; Bates. Tim; O'Dowd, Colin; Reid, Jeff; Lewis, Ernie R.; Gantt, Brett; Anguelova, Magdalena D.; Bhave, Prakash V.; Bird, James; Callaghan, Adrian H.; Ceburnis, Darius; Chang, Rachel; Clark, Antony; deLeeuw, Gerrit; Deane, Grant; DeMott, Paul J.; Elliot, Scott; Facchini, Maria Cristina; Fairall, Chris W.; Hawkins, Lelia; Hu, Yongxiang; Smirnov, Alexander

    2013-01-01

    Over forty scientists from six countries convened in Raleigh, NC on June 4-6 2012 to review the status and prospects of sea spray aerosol research. Participants were researchers from the oceanography and atmospheric science communities, including academia, private industry, and government agencies. The recommendations from the working groups are summarized in a science prioritization matrix that is meant to prioritize the research agenda and identify areas of investigation by the magnitude of their impact on proposed science questions. Str

  9. Characterization of aerosols in the Norwegian subarctic region (ALOMAR station): Optical properties, size distributions and nucleation events

    Science.gov (United States)

    Mogo, S.; Cachorro, V. E.; de Frutos, A. M.; Lopez, J. F.; Torres, B.; Bennouna, Y.

    2013-05-01

    During the 2008 summer, a field campaign was carried out at the Arctic Lidar Observatory for Middle Atmosphere Research, ALOMAR, on Ando/ya island close to the town of Andenes (69° 16'N, 16° 00'E, 380 m a.s.l.), approximately 300 km north of the Arctic Circle. The campaign was part of the contribution of the Atmospheric Optics Group of the Valladolid University (GOA-UVa) to the International Polar Year, in the framework of the POLARCAT (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models of Climate, Chemistry, Aerosols, and Transport) project. This GOA-UVa's field campaign has been developed to obtain experimental data for local aerosols, its optical characteristics (absorption / scattering coefficients and single scattering albedo), its size distributions and derived parameters. For this purpose, different instruments were simultaneously installed in the station facilities. These are the first measurements with this variety of information reported in the station and can be extrapolated over a wide area around.

  10. Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean

    Science.gov (United States)

    Denjean, C.; Cassola, F.; Mazzino, A.; Triquet, S.; Chevaillier, S.; Grand, N.; Bourrianne, T.; Momboisse, G.; Sellegri, K.; Schwarzenbock, A.; Freney, E.; Mallet, M.; Formenti, P.

    2016-02-01

    This study presents in situ aircraft measurements of Saharan mineral dust transported over the western Mediterranean basin in June-July 2013 during the ChArMEx/ADRIMED (the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) airborne campaign. Dust events differing in terms of source region (Algeria, Tunisia and Morocco), time of transport (1-5 days) and height of transport were sampled. Mineral dust were transported above the marine boundary layer, which conversely was dominated by pollution and marine aerosols. The dust vertical structure was extremely variable and characterized by either a single layer or a more complex and stratified structure with layers originating from different source regions. Mixing of mineral dust with pollution particles was observed depending on the height of transport of the dust layers. Dust layers carried a higher concentration of pollution particles below 3 km above sea level (a.s.l.) than above 3 km a.s.l., resulting in a scattering Ångström exponent up to 2.2 below 3 km a.s.l. However, the optical properties of the dust plumes remained practically unchanged with respect to values previously measured over source regions, regardless of the altitude. Moderate absorption of light by the dust plumes was observed with values of aerosol single scattering albedo at 530 nm ranging from 0.90 to 1.00. Concurrent calculations from the aerosol chemical composition revealed a negligible contribution of pollution particles to the absorption properties of the dust plumes that was due to a low contribution of refractory black carbon in regards to the fraction of dust and sulfate particles. This suggests that, even in the presence of moderate pollution, likely a persistent feature in the Mediterranean, the optical properties of the dust plumes could be assumed similar to those of native dust in radiative transfer simulations, modelling studies and satellite retrievals

  11. Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean

    Directory of Open Access Journals (Sweden)

    C. Denjean

    2015-08-01

    Full Text Available This study presents in situ aircraft measurements of Saharan mineral dust transported over the western Mediterranean basin in June–July 2013 during the ChArMEx/ADRIMED (the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region airborne campaign. Dust events differing in terms of source region (Algeria, Tunisia and Morocco, time of tranport (1–5 days and height of transport were sampled. Mineral dust were transported above the marine boundary layer, which conversely was dominated by pollution and marine aerosols. The dust vertical structure was extremely variable and characterized by either a single layer or a more complex and stratified structure with layers originating from different source regions. Mixing of mineral dust with pollution particles was observed depending on the height of transport of the dust layers. Dust layers carried higher concentration of pollution particles at intermediate altitude (1–3 km than at elevated altitude (> 3 km, resulting in scattering Angstrom exponent up to 2.2 within the intermediate altitude. However, the optical properties of the dust plumes remained practically unchanged with respect to values previously measured over source regions, regardless of the altitude. Moderate light absorption of the dust plumes was observed with values of aerosol single scattering albedo at 530 nm ranging from 0.90 to 1.00 ± 0.04. Concurrent calculations from the aerosol chemical composition revealed a negligible contribution of pollution particles to the absorption properties of the dust plumes that was due to a low contribution of refractory black carbon in regards to the fraction of dust and sulfate particles. This suggests that, even in the presence of moderate pollution, likely a persistent feature in the Mediterranean, the optical properties of the dust plumes could be assimilated to those of native dust in radiative transfer simulations

  12. Performance of High Flow Rate Personal Respirable Samplers When Challenged with Mineral Aerosols of Different Particle Size Distributions

    OpenAIRE

    Stacey, Peter; Thorpe, Andrew; Echt, Alan

    2016-01-01

    It is thought that the performance of respirable samplers may vary when exposed to dust aerosols with different particle sizes and wind speeds. This study investigated the performance of the GK 4.16 (RASCAL), GK 2.69, PPI 8, and FSP 10, high flow rate personal samplers when exposed to aerosols of mineral dust in a wind tunnel at two different wind speeds (1 and 2 m s−1) and orientations (towards and side-on to the source of emission). The mass median aerodynamic diameter of four aerosolized t...

  13. Effects of atmospheric humidity on the refractive index and the size distribution of aerosols as estimated from light scattering measurements.

    OpenAIRE

    Takamura, Tamio; Tanaka, Masayuki; Nakajima, Teruyuki

    1984-01-01

    The complex index of refraction, scattering cross section and albedo for single scattering have been estimated from measurements of the angular distribution of light scattered by aerosol particles, by an inversion library method. The humidity dependence of these optical properties has been examined in compiling 250 samples for the period FebruaryNovember 1978. It is found that optical properties of aerosol particles change systematically according to the change of relative humidity. The humid...

  14. Size distribution characteristics of carbonaceous aerosol in Xishuangbanna, southwest China: a sign for biomass burning in Asia.

    Science.gov (United States)

    Guo, Yuhong

    2016-03-01

    In 2012, size-segregated aerosol samples were collected in Xishuangbanna, a forest station in southwest China. The concentrations of organic and elemental carbon (OC and EC for short) were quantified with thermal/optical carbon analyzer in the filter samples. OC and EC exhibited similar seasonal patterns, with the highest concentrations in spring, possibly due to the influence of biomass burning in south and southeast Asia. The mass size distributions of OC and EC were bimodal in all the sampling seasons, each with a dominant peak in the fine mode of 0.4-0.7 μm and a coarse peak in the size range of 2.1-4.7 μm. In fine mode, OC and EC showed smaller geometric mean diameters (GMDs) during winter. OC and EC were prone to be more concentrated in fine particles in spring and winter than in summer and autumn. Furthermore, EC was more abundant in fine particles than OC. Good correlations (R (2) = 0.75-0.82) between OC and EC indicated that they had common dominant sources of combustion such as biomass burning and fossil fuel combustion emissions. The daily average OC/EC ratios ranged from 2.1 to 9.1, more elevated OC/EC ratios being found in the winter. PMID:26851952

  15. Charge distributions and coagulation of radioactive aerosols

    International Nuclear Information System (INIS)

    The self-charging of radioactive aerosols will be reduced by background ions, such as those produced by radioactive gases. The sources of these background ions and their production rates are specified for a reactor containment atmosphere during a possible nuclear accident. Previous theory is extended to calculate the charging of a polydisperse radioactive aerosol. Gaussian approximations to charge distributions on an aerosol of a given size, and are shown to give a good representation of the exact numerical charge distributions of a Cs aerosol at normal temperatures, and also for highly radioactive aerosol containing 131I in a containment atmosphere. Extensive calculations are performed for charged-induced modifications to Brownian coagulation rates between steady-state size distribution of these radioactive aerosols, and also between small-sized radioactive aerosol and larger (non-radioactive) aerosol. The results show considerable enhancements of the coagulation rates between large and small-sized aerosol, but also a strong suppression of coagulation between large particles. Rate modifications calculated using the Gaussian approximations are generally close to the exact values. Time-dependent calculations for a monodisperse α-decaying aerosol reveal enhancements in coagulation rates even when the average charge on the aerosol is positive. Our results are relevant to behaviour in a dusty plasma. (author)

  16. Inertial classification of aerosols for size measurement

    International Nuclear Information System (INIS)

    Major inertial size classification techniques and devices have been reviewed. Principles of operation, advantages and limitations of each technique, precautions to be taken in design and operation of the devices are discussed with respect to their applications to nuclear aerosol analyses. Included in the review are sedimentation chambers, elutriators, cascade impactors, centrifuges and cyclones. Based on the comparison of various techniques, it has been concluded that spiral duct centrifuges and cascade impactors are suitable for measuring the aerosol size distribution for nuclear aerosol applications. It is also emphasized that because of the possible operational problems and the variations in performance resulting from sampling conditions, any inertial aerosol measurement device should be calibrated and evaluated under conditions as close as possible to the experimental conditions expected during their use

  17. Measurements in a highly polluted Asian mega city: observations of aerosol number size distribution, modal parameters and nucleation events

    Directory of Open Access Journals (Sweden)

    P. Mönkkönen

    2005-01-01

    Full Text Available Diurnal variation of number size distribution (particle size 3-800nm and modal parameters (geometric standard deviation, geometric mean diameter and modal aerosol particle concentration in a highly polluted urban environment was investigated during October and November 2002 in New Delhi, India. Continuous monitoring for more than two weeks with the time resolution of 10min was conducted using a Differential Mobility Particle Sizer (twin DMPS. The results indicated clear increase in Aitken mode (25-100nm particles during traffic peak hours, but towards the evenings there were more Aitken mode particles compared to the mornings. Also high concentrations of accumulation mode particles (>100nm were detected in the evenings only. In the evenings, biomass/refuse burning and cooking are possible sources beside the traffic. We have also shown that nucleation events are possible in this kind of atmosphere even though as clear nucleation events as observed in rural sites could not be detected. The formation rate of 3nm particles (J3 of the observed events varied from 3.3 to 13.9cm-3s-1 and the growth rate varied from 11.6 to 18.1nmh-1 showing rapid growth and high formation rate, which seems to be typical in urban areas.

  18. Measurements in a highly polluted Asian mega city: observations of aerosol number size distribution, modal parameters and nucleation events

    Directory of Open Access Journals (Sweden)

    P. Mönkkönen

    2004-09-01

    Full Text Available Diurnal variation of number size distribution (particle size 3–800 nm and modal parameters (geometric standard deviation, geometric mean diameter and modal aerosol particle concentration in a highly polluted urban environment was investigated during October and November 2002 in New Delhi, India. Continuous monitoring for more than two weeks with the time resolution of 10 min was conducted using a Differential Mobility Particle Sizer (twin DMPS. The results indicated clear increase in Aitken mode (25–100 nm particles during traffic peak hours, but towards the evenings there were more Aitken mode particles compared to the mornings. Also high concentrations of accumulation mode particles (>100 nm were detected in the evenings only. In the evenings, biomass/refuse burning and cooking are possible sources beside the traffic. We have also shown that nucleation events are possible in this kind of atmosphere even though as clear nucleation events as observed in rural sites could not be detected. The formation rate of 3 nm particles (J3 of the observed events varied from 3.3 to 13.9 cm−3s−1 and the growth rate varied from 11.6 to 18.1 nmh−1 showing rapid growth and high formation rate, which seems to be typical in urban areas.

  19. Calibration method for a photoacoustic system for real time source apportionment of light absorbing carbonaceous aerosol based on size distribution measurements

    Science.gov (United States)

    Utry, Noemi; Ajtai, Tibor; Pinter, Mate; Orvos, Peter I.; Szabo, Gabor; Bozoki, Zoltan

    2016-04-01

    In this study, we introduce a calibration method with which sources of light absorbing carbonaceous particulate matter (LAC) can be apportioned in real time based on multi wavelength optical absorption measurements with a photoacoustic system. The method is primary applicable in wintry urban conditions when LAC is dominated by traffic and biomass burning. The proposed method was successfully tested in a field campaign in the city center of Szeged, Hungary during winter time where the dominance of traffic and wood burning aerosol has been experimentally demonstrated earlier. With the help of the proposed calibration method a relationship between the measured Aerosol Angström Exponent (AAE) and the number size distribution can be deduced. Once the calibration curve is determined, the relative strength of the two pollution sources can be deduced in real time as long as the light absorbing fraction of PM is exclusively related to traffic and wood burning. This assumption is indirectly confirmed in the presented measurement campaign by the fact that the measured size distribution is composed of two unimodal size distributions identified to correspond to traffic and wood burning aerosols. The proposed method offers the possibility of replacing laborious chemical analysis with simple in-situ measurement of aerosol size distribution data.

  20. Diurnal and seasonal variations of concentration and size distribution of nano aerosols (10-1100 nm) enclosing radon decay products in the Postojna Cave, Slovenia

    International Nuclear Information System (INIS)

    At the lowest point along the tourist route in the Postojna Cave, the activity concentration of radon (222Rn) short-lived decay products and number concentration and size distribution of background aerosol particles in the size range of 10-1100 nm were measured. In the warm yearly season, aerosol concentration was low (52 cm-3) with 21 % particles smaller than 50 nm, while in the cold season, it was higher (1238 cm-3) with 8 % of -3, and fractions of unattached radon decay products were 0.62 and 0.13, respectively. (authors)

  1. Coagulation effect on the activity size distributions of long lived radon progeny aerosols and its application to atmospheric residence time estimation techniques

    International Nuclear Information System (INIS)

    The long lived naturally occurring radon progeny species in the atmosphere, namely 210Pb, 210Bi and 210Po, have been used as important tracers for understanding the atmospheric mixing processes and estimating aerosol residence times. Several observations in the past have shown that the activity size distribution of these species peaks at larger particle sizes as compared to the short lived radon progeny species – an effect that has been attributed to the process of coagulation of the background aerosols to which they are attached. To address this issue, a mathematical equation is derived for the activity-size distribution of tracer species by formulating a generalized distribution function for the number of tracer atoms present in coagulating background particles in the presence of radioactive decay and removal. A set of these equations is numerically solved for the progeny chain using Fuchs coagulation kernel combined with a realistic steady-state aerosol size spectrum that includes nucleation, accumulation and coarse mode components. The important findings are: (i) larger shifts in the modal sizes of 210Pb and 210Po at higher aerosol concentrations such as that found in certain Asian urban regions (ii) enrichment of tracer specific activity on particles as compared to that predicted by pure attachment laws (iii) sharp decline of daughter-to-parent activity ratios for decreasing particle sizes. The implication of the results to size-fractionated residence time estimation techniques is highlighted. A coagulation corrected graphical approach is presented for estimating the residence times from the size-segregated activity ratios of 210Bi and 210Po with respect to 210Pb. The discrepancy between the residence times predicted by conventional formula and the coagulation corrected approach for specified activity ratios increases at higher atmospheric aerosol number concentrations (>1010/m3) for smaller sizes (<1 μm). The results are further discussed. - Highlights:

  2. The mathematical principles and design of the NAIS – a spectrometer for the measurement of cluster ion and nanometer aerosol size distributions

    Directory of Open Access Journals (Sweden)

    S. Mirme

    2013-04-01

    Full Text Available The paper describes the Neutral cluster and Air Ion Spectrometer (NAIS – a multichannel aerosol instrument capable of measuring the distribution of ions (charged particles and cluster ions of both polarities in the electric mobility range from 3.2 to 0.0013 cm2 V−1 s−1 and the distribution of aerosol particles in the size range from 2.0 to 40 nm. We introduce the principles of design, data processing and spectrum deconvolution of the instrument.

  3. Impact of relative humidity and particles number size distribution on aerosol light extinction in the urban area of Guangzhou

    OpenAIRE

    Z. J. Lin; J. Tao; Chai, F. H; S. J. Fan; Yue, J.H.; Zhu, L. H.; Ho, K. F; R. J. Zhang

    2013-01-01

    In the urban area of Guangzhou, observations on aerosol light extinction effect were conducted at a monitoring site of the South China Institute of Environmental Sciences (SCIES) during April 2009, July 2009, October 2009 and January 2010. The main goal of these observations is to recognise the impact of relative humidity (RH) and particles number distribution on aerosol light extinction. PM2.5 was sampled by Model PQ200 air sampler; ions and OC/EC in PM2.5&l...

  4. Roles of saltation, sandblasting, and wind speed variability on mineral dust aerosol size distribution during the Puerto Rican Dust Experiment (PRIDE)

    OpenAIRE

    Grini, A.; Zender, C. S.

    2004-01-01

    Recent field observations demonstrate that a significant discrepancy exists between models and measurements of large dust aerosol particles at remote sites. We assess the fraction of this bias explained by assumptions involving four different dust production processes. These include dust source size distribution (constant or dynamically changing according to saltation and sandblasting theory), wind speed distributions (using mean wind or a probability density function (PDF)), parent soil aggr...

  5. 丝网法测量纳米级气溶胶颗粒粒径分布的方法研究%Measurement of the Size Distribution of Nano-Sized Aerosols with the Wire-Screen Method

    Institute of Scientific and Technical Information of China (English)

    陈波; 张磊; 卓维海

    2011-01-01

    [目的]探讨纳米级气溶胶颗粒粒径分布测量的新方法.[方法]根据丝网采集气溶胶的基本原理,建立利用丝网组合测量纳米级气溶胶颗粒粒径分布的方法,并通过比对试验和现场测量验证该方法的可行性.[结果]经比对实验,结果表明两种不同方法的测量结果基本吻合;现场测量结果表明,室内气溶胶颗粒物的中位值和粒径分布因环境条件变化而有波动.[结论]本研究建立的测量方法可用于测量粒径10~300nm气溶胶颗粒物的粒径分布.%[ Objective ] To develop a simplified method for measuring the size distribution of nano-sized aerosols. [ Methods ] Based on the fundamental principles of aerosol capture on wire screens, a method adopting wire screens was developed for measuring the size distribution of nano-sized aerosols, its feasibility was verified through comparison experiments and field application.[ Results ] Comparison of the results showed that the measured size distribution of aerosols were nearly the same with the two methods. Field measurements also showed that both the median size and its distribution of indoor aerosols varied with the changes of environmental factors. [ Conclusion ] The new measuring method could be used for measurement of the size distributions of aerosols in a range of l0nm to 300 nm.

  6. Aerosol and NOx emission factors and submicron particle number size distributions in two road tunnels with different traffic regimes

    Directory of Open Access Journals (Sweden)

    D. Imhof

    2006-01-01

    Full Text Available Measurements of aerosol particle number size distributions (18–700 nm, mass concentrations (PM2.5 and PM10 and NOx were performed in the Plabutsch tunnel, Austria, and in the Kingsway tunnel, United Kingdom. These two tunnels show different characteristics regarding the roadway gradient, the composition of the vehicle fleet and the traffic frequency. The submicron particle size distributions contained a soot mode in the diameter range D=80–100 nm and a nucleation mode in the range of D=20–40 nm. In the Kingsway tunnel with a significantly lower particle number and volume concentration level than in the Plabutsch tunnel, a clear diurnal variation of nucleation and soot mode particles correlated to the traffic density was observed. In the Plabutsch tunnel, soot mode particles also revealed a diurnal variation, whereas no substantial variation was found for the nucleation mode particles. During the night a higher number concentration of nucleation mode particles were measured than soot mode particles and vice versa during the day. In this tunnel with very high soot emissions during daytime due to the heavy-duty vehicle (HDV share of 18% and another 40% of diesel driven light-duty vehicles (LDV semivolatile species condense on the pre-existing soot surface area rather than forming new particles by homogeneous nucleation. With the low concentration of soot mode particles in the Kingsway tunnel, also the nucleation mode particles exhibit a diurnal variation. From the measured parameters real-world traffic emission factors were estimated for the whole vehicle fleet as well as differentiated into the two categories LDV and HDV. In the particle size range D=18–700 nm, each vehicle of the mixed fleet emits (1.50±0.08×1014 particles km-1 (Plabutsch and (1.26±0.10×1014 particles km-1 (Kingsway, while particle volume emission factors of 0.209±0.008 cm3 km-1 and 0.036±0.004 cm3 km-1, respectively, were obtained. PM1 emission factors of 104±4 mg

  7. Size distribution, composition and origin of the submicron aerosol in the marine boundary layer during the eastern Mediterranean "SUB-AERO" experiment

    Science.gov (United States)

    Eleftheriadis, K.; Colbeck, I.; Housiadas, C.; Lazaridis, M.; Mihalopoulos, N.; Mitsakou, C.; Smolík, J.; Ždímal, V.

    A period of intensive physical and chemical aerosol characterisation measurements was held over 5 days during July 2000 as part of the European SUB-AERO experiment.. Concurrent measurements were performed at the Finokalia remote coastal site on the island of Crete (Greece) and onboard the R/V " Aegaeon" which cruised in south part of the Aegean Sea northwards of Crete. The objective of the study was to investigate the spatial and temporal variability of microphysical parameters of the submicron aerosol and their dependence on airmass origin and chemical composition. The results reflect the submicron aerosol properties during airmass transport from the north including Europe and the Balkans and are in line with other studies on the aerosol properties of polluted continental air entering the marine boundary layer (MBL). Concentrations of submicron particulate matter (PM) mass were relatively higher at sea (20 μg m -3) compared to the coastal site (16 μg m -3). Concentrations of both organic carbon and sulphate, being the major water soluble component, were also higher at sea than at land. The high concentrations of ammonium and those of the water soluble organics, such as oxalate, can be attributed to emissions from mainland forest fires. The submicron aerosol number size distribution was unimodal with mobility mean diameters ( dg) ranging from 98 to 144 μm and standard deviations ( σg) from 1.56 to 1.9. Aerosol number concentrations at Finokalia were at least 50% lower especially when R/V Aegaeon sampled polluted air, but the modal parameters of the size distribution were very similar ( dg: 111-120, σg: 1.55-1.91). The surface MBL, under these conditions, was an aerosol rich environment where aerosol particles were transported both by the surface wind, advected from higher layers, chemically processed by interactions with gaseous precursors and physically altered by water vapour. The number to volume ratio for the submicrometer aerosol fraction reflected the

  8. The study on differentiated particle size sampling technology of aerosols

    International Nuclear Information System (INIS)

    This article introduces basic principle of differentiated particle size sampling technology of aerosols. This sampling technology is used to conduct a experimental research on the aerosols particles size distribution of uranium and radon and it's daughters. Experimental results showed that the part of radon and it's daughters aerosols particles size smaller than 0.43 μm reached 76.4%. The part of radon and it's daughters aerosols particles size less than 1 μm reached 96.3%. The part of uranium aerosol particles size larger than 4.7 μm under specific conditions is 94%, the part of aerosol particles size larger than 10 μm is 72%. According to the experiment's result, we designed a new sampling equipments that cutting size is 1 μm to collect samples of aerosols, and it is used in the separation efficiency experiments of 241Am aerosols. Experimental results showed that the separation efficiency of 241Am aerosols can reach 94.2%. Thus, using the differentiated particle size sampling technology to collect samples of plutonium aerosols, in the sampling process can reduce the effect of natural background aerosols. (authors)

  9. 40 CFR Table F-6 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Estimated Mass Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution F Table F-6 to Subpart F of Part 53... Equivalent Methods for PM2.5 Pt. 53, Subpt. F, Table F-6 Table F-6 to Subpart F of Part 53—Estimated...

  10. 40 CFR Table F-4 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized Coarse Aerosol Size Distribution

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Estimated Mass Concentration Measurement of PM2.5 for Idealized Coarse Aerosol Size Distribution F Table F-4 to Subpart F of Part 53... Equivalent Methods for PM2.5 Pt. 53, Subpt. F, Table F-4 Table F-4 to Subpart F of Part 53—Estimated...

  11. Observation of aerosol size distribution and new particle formation at a coastal city in the Yangtze River Delta, China.

    Science.gov (United States)

    Shen, Lijuan; Wang, Honglei; Lü, Sheng; Li, Li; Yuan, Jing; Zhang, Xiaohan; Tian, Xudong; Tang, Qian

    2016-09-15

    Aerosol number size distribution in the range of 10nm-10μm, trace gases (O3, CO, SO2 and NO2), particular matter (PM: PM2.5 and PM10) and meteorological elements were measured from the 1st to the 31st of May, 2015, in the coastal city of Jiaxing in the Yangtze River Delta (YRD). The average number concentration and surface area concentration were 19,639cm(-3) and 427μm(2)cm(-3) during the observation period. The different mode particle concentrations ranked in the order of Aitken mode (12,361cm(-3))>nucleation (4926.7cm(-3))>accumulation (2349.3cm(-3))>coarse mode (1.7cm(-3)). The average concentrations of CO, SO2, NO2, O3, PM2.5 and PM10 were 0.545mgm(-3), 14.7, 35.1, 89.8, 43.5 and 64.6μgm(-3), respectively. Eight precipitation processes and 15 new particle formation (NPF) events (3 NPF events occurred on a rainy day) were observed. Results show that the precipitation process had greater scavenging effects on particles smaller than 120nm and larger than 2μm. The spectral distributions of number concentrations were unimodal at different weather conditions, with peaks at 20nm, 40-60nm, 50-80nm on NPF days, rainy days and normal days. During the NPF events, the formation rate (FR), growth rate (GR), condensational sink (CS), vapor source rate (Q) and condensing vapor concentration (C) were in the range of 4.0-17.0cm(-3)s(-1), 2.2-15.7nmh(-1), 1.5-5.8×10(-2)s(-1), 0.5-7.7×10(6)cm(-3)s(-1) and 3.0-21.5×10(7)cm(-3), with mean values of 9.6cm(-3)s(-1), 6.8nmh(-1), 3.4×10(-2)s(-1), 3.3×10(6)cm(-3)s(-1) and 9.4×10(7)cm(-3), respectively. NPF events normally occurred under clean atmospheric conditions with low PM concentrations but high levels of trace gases. It was also found that SO2 plays an important role in NPF and growth in Jiaxing. PMID:27261424

  12. Performance of High Flow Rate Personal Respirable Samplers When Challenged with Mineral Aerosols of Different Particle Size Distributions.

    Science.gov (United States)

    Stacey, Peter; Thorpe, Andrew; Echt, Alan

    2016-05-01

    It is thought that the performance of respirable samplers may vary when exposed to dust aerosols with different particle sizes and wind speeds. This study investigated the performance of the GK 4.16 (RASCAL), GK 2.69, PPI 8, and FSP 10, high flow rate personal samplers when exposed to aerosols of mineral dust in a wind tunnel at two different wind speeds (1 and 2 m s(-1)) and orientations (towards and side-on to the source of emission). The mass median aerodynamic diameter of four aerosolized test dusts ranged from 8 to 25 µm with geometric standard deviations from 1.6 to 2 µm. The performance of each sampler type was compared with that of the SIMPEDS (Higgins-Dewell design) sampler. There was slight evidence to suggest that the performance of the FSP 10 is affected by the direction of the inlet relative to the air flow, although this was not significant when most respirable dust concentrations were compared, possibly due to the variability of paired dust concentration results. The GK 2.69, RASCAL, and PPI 8 samplers had similar performances, although the results when side-on to the emission source were generally slightly lower than the SIMPEDS. Despite slight differences between respirable dust concentrations the respirable crystalline silica values were not significantly different from the SIMPEDS. The GK family of cyclones obtained most precise results and more closely matched the SIMPEDS. A comparison with dust concentration results from previous calm air chamber studies (where wind speeds were < 0.4 m s(-1)) found that the relative performance between samplers was similar to those observed in this work indicating consistent performance relative to the SIMPEDS in both calm and moving air. PMID:26865560

  13. The ion–aerosol interactions from the ion mobility and aerosol particle size distribution measurements on January 17 and February 18, 2005 at Maitri, Antarctica – A case study

    Indian Academy of Sciences (India)

    Devendraa Siingh; Vimlesh Pant; A K Kamra

    2011-08-01

    A case study for the ion–aerosol interactions is presented from the simultaneous measurements of mobility spectra of atmospheric ions in the mobility range of 2.29 to 2.98 × 10−4 cm2 V−1 s−1 (diameter range 0.41–109 nm) and of size distribution of atmospheric aerosol particles in the size ranges of 4.4–700 nm and 500–20,000 nm diameters made at Maitri (70° 45′ 52′′S, 11° 44′ 2.7′′E; 130 m above mean sea level), Antarctica, on two days January 17 and February 18, 2005, with contrasting meteorological conditions. In contrast to January 17, on February 18, winds were stronger from the morning to noon and lower from the noon to evening, atmospheric pressure was lower, cloudiness was more, the land surface remained snow-covered after a blizzard on February 16 and 17 and the airmass over Maitri, descended from an altitude of ∼3 km after an excursion over ocean. On these days mobility spectra showed two modes, corresponding to intermediate ions and light large ions and an indication of additional one/two maxima for small/cluster ions and heavy large ions. The small ions generated by cosmic rays, and the nucleation mode particles generated probably by photochemical reactions grew in size by condensation of volatile trace gases on them and produced the cluster and intermediate ion modes and the Aitken particle mode in ion/particle spectra. Particles in the size range of 9–26 nm have been estimated to grow at the rate of 1.9 nm h−1 on February 18, 2005. Both, ions and aerosol particles show bimodal size distributions in the 16–107 nm size range, and comparison of the two size distributions suggests the formation of multiple charged ions. Attachment of small ions to particles in this bimodal distribution of Aitken particles together with the formation of multiple charged ions are proposed to result in the light and heavy large ion modes. Growth of the nucleation mode particles on February 18, 2005 is associated with the passage of the

  14. 生物气溶胶粒径分布及稳定性研究%RESEARCH ON DISTRIBUTION OF PARTICLE SIZE AND STABILITY OF BIO -AEROSOL

    Institute of Scientific and Technical Information of China (English)

    魏兰芬; 张磊; 许激; 潘协商; 朱一凡; 林军明

    2011-01-01

    Objective To study the particle size distribution and stability of bio - aerosol and its correlation with aerosol microbes.Methods Particle counter and aerosol microbe sampler were applied to the tests and analysis.Results The diameters of most aerosol particles of Staphylococcus albicans generated with the CN61 aerosol generator were < 2.0 μm.The amount of particles was stable with the first 1 h after being generated.The decaying rate increased considerably with the increase of particle size.The decaying rate of 1.0 ~2.0 μm particles was ≤27.7% while that of particle >5.0 μm was ≥73.7% in 1 hour.Aerosol bacteria captured by level 3,4 and 5 of six - level Anderson sampler each occupied about 20%of total amount respectively and 10% each for level 1,2 and 6.The average decaying rate of aerosol bacteria was 8.3%within the first 1 h which was similar with particles > 2.0μm.Conclusion The amounts of aerosol particles and microbes have good correlation.The CN61 aerosol generator can produce aerosol with particle size distribution and stability meeting the demand of disinfection study.%目的 研究生物气溶胶粒径分布、稳定性及其与浮游菌的相关性.方法 采用仪器法采样和测定方法,对实验室发生的气溶胶颗粒大小分布及空气中浮游菌颗粒进行了分析.结果 用CN61气溶胶发生器制备的白色葡萄球菌气溶胶颗粒直径多数在2.0μm以下,在发生后1 h内,总粒子稳定性良好,不同粒径粒子的自然消亡率随粒径增加而明显增加.在1 h内,粒径在1.0~2.0μm的颗粒衰减率≤27.7%,粒径在5.0μm以上颗粒的衰减率≥73,7%.用六级安德森采样器进行采样,3、4、5级对空气中细菌颗粒捕获率各为20%左右,1、2、6级捕获率约占10%左右.在气溶胶发生后1 h内,空气中浮游菌自然消亡率平均值为8.3%,与2.0μm以上粒子的降解较为一致.结论 物理粒子计数与浮游菌数两者之

  15. Long-term observations of tropospheric particle number size distributions and equivalent black carbon mass concentrations in the German Ultrafine Aerosol Network (GUAN

    Directory of Open Access Journals (Sweden)

    W. Birmili

    2015-11-01

    Full Text Available The German Ultrafine Aerosol Network (GUAN is a cooperative atmospheric observation network, which aims at improving the scientific understanding of aerosol-related effects in the troposphere. The network addresses research questions dedicated to both, climate and health related effects. GUAN's core activity has been the continuous collection of tropospheric particle number size distributions and black carbon mass concentrations at seventeen observation sites in Germany. These sites cover various environmental settings including urban traffic, urban background, rural background, and Alpine mountains. In association with partner projects, GUAN has implemented a high degree of harmonisation of instrumentation, operating procedures, and data evaluation procedures. The quality of the measurement data is assured by laboratory intercomparisons as well as on-site comparisons with reference instruments. This paper describes the measurement sites, instrumentation, quality assurance and data evaluation procedures in the network as well as the EBAS repository, where the data sets can be obtained (doi:10.5072/guan.

  16. One-year observations of size distribution characteristics of major aerosol constituents at a coastal receptor site in Hong Kong – Part 1: Inorganic ions and oxalate

    Directory of Open Access Journals (Sweden)

    Q. Bian

    2014-01-01

    Full Text Available Size distribution data of major aerosol constituents are essential in source apportioning of visibility degradation, testing and verification of air quality models incorporating aerosols. We report here one-year observations of mass size distributions of major inorganic ions (sulfate, nitrate, chloride, ammonium, sodium, potassium, magnesium and calcium and oxalate at a coastal suburban receptor site in Hong Kong, China. A total of 43 sets of size segregated samples in the size range of 0.056–18 μm were collected from March 2011 to February 2012. The size distributions of sulfate, ammonium, potassium and oxalate were characterized by a dominant droplet mode with a mass mean aerodynamic diameter (MMAD in the range of ~0.7–0.9 μm. Oxalate had a slightly larger MMAD than sulfate on days with temperatures above 22 °C as a result of the process of volatilization and repartitioning. Nitrate was mostly dominated by the coarse mode but enhanced presence in fine mode was detected on winter days with lower temperature and lower concentrations of sea salt and soil particles. This data set reveals an inversely proportional relationship between the fraction of nitrate in the fine mode and product of the sum of sodium and calcium in equivalent concentrations and the dissociation constant of ammonium nitrate (i.e., (1/[Na+] + 2[Ca2+] × (1/Ke'. The seasonal variation observed for sea salt aerosol abundance, with lower values in summer and winter, is possibly linked with the lower marine salinities in these two seasons. Positive matrix factorization was applied to estimate the relative contributions of local formation and transport to the observed ambient sulfate level through the use of the combined datasets of size-segregated sulfate and select gaseous air pollutants. On average, the regional/super-regional transport of air pollutants was the dominant source at this receptor site, especially on high sulfate days, while local formation processes

  17. One-year observations of size distribution characteristics of major aerosol constituents at a coastal receptor site in Hong Kong - Part 1: Inorganic ions and oxalate

    Science.gov (United States)

    Bian, Q.; Huang, X. H. H.; Yu, J. Z.

    2014-09-01

    Size distribution data of major aerosol constituents are essential in source apportioning of visibility degradation, testing and verification of air quality models incorporating aerosols. We report here 1-year observations of mass size distributions of major inorganic ions (sulfate, nitrate, chloride, ammonium, sodium, potassium, magnesium and calcium) and oxalate at a coastal suburban receptor site in Hong Kong, China. A total of 43 sets of size-segregated samples in the size range of 0.056-18 μm were collected from March 2011 to February 2012. The size distributions of sulfate, ammonium, potassium and oxalate were characterized by a dominant droplet mode with a mass mean aerodynamic diameter (MMAD) in the range of ~ 0.7-0.9 μm. Oxalate had a slightly larger MMAD than sulfate on days with temperatures above 22 °C as a result of the process of volatilization and repartitioning. Nitrate was mostly dominated by the coarse mode but enhanced presence in fine mode was detected on winter days with lower temperature and lower concentrations of sea salt and soil particles. This data set reveals an inversely proportional relationship between the fraction of nitrate in the fine mode and product of the sum of sodium and calcium in equivalent concentrations and the dissociation constant of ammonium nitrate (i.e., (1/([Na+] + 2[Ca2+]) × (1/Ke')) when Pn_fine is significant (> 10%). The seasonal variation observed for sea salt aerosol abundance, with lower values in summer and winter, is possibly linked with the lower marine salinities in these two seasons. Positive matrix factorization was applied to estimate the relative contributions of local formation and transport to the observed ambient sulfate level through the use of the combined data sets of size-segregated sulfate and select gaseous air pollutants. On average, the regional/super-regional transport of air pollutants was the dominant source at this receptor site, especially on high-sulfate days while local formation

  18. The self-preserving size distribution theory. II. Comparison with experimental results for Si and Si3N4 aerosols.

    Science.gov (United States)

    Dekkers, Petrus J; Tuinman, Ilse L; Marijnissen, Jan C M; Friedlander, Sheldon K; Scarlett, B

    2002-04-15

    The gas to particle synthesis route is a relatively clean and efficient manner for the production of high-quality ceramic powders. These powders can be subsequently sintered in any wanted shape. The modeling of these production systems is difficult because several mechanisms occur in parallel. From theoretical considerations it can be determined, however, that coagulation and sintering are dominant mechanisms as far as shape and size of the particles are considered. In part I of this article an extensive theoretical analysis was given on the self-preserving size distribution theory for power law particles. In this second part, cumulative particle size distributions of silicon and silicon nitride agglomerates, produced in a laser reactor, were determined from TEM pictures and compared to the distributions calculated from this self-preserving theory for power law particles. The calculated distributions were in fair agreement with the measured results, especially at the high end of the distributions. Calculated and measured particle growth rates were also in fair agreement. Using the self-preserving theory an analysis was made on the distribution of annealed silicon agglomerates, of interest in applications to nanoparticle technology. PMID:16290535

  19. Theoretical Mass Size Distribution of Wet Particles Calculated from Ambient Aerosol Sampled upon Dry Conditions during Summer and Winter Campaign 2008

    Czech Academy of Sciences Publication Activity Database

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

    Praha: Česká aerosolová společnost, 2008, s. 29-30. ISBN 978-80-86186-17-7. [konference České aerosolové společnosti /9./. Praha (CZ), 04.12.2008] R&D Projects: GA MŠk OC 106; GA MŠk ME 941 Institutional research plan: CEZ:AV0Z40720504 Keywords : mass size distribution * urban aerosol * cascade impactor Subject RIV: CF - Physical ; Theoretical Chemistry http://cas.icpf.cas.cz/download/Sbornik_VKCAS_2008.pdf

  20. Classifying previously undefined days from eleven years of aerosol-particle-size distribution data from the SMEAR II station, Hyytiälä, Finland

    Directory of Open Access Journals (Sweden)

    S. Buenrostro Mazon

    2009-01-01

    Full Text Available Studies of secondary aerosol-particle formation depend on identifying days in which new particle formation occurs and, by comparing them to days with no signs of particle formation, identifying the conditions favourable for formation. Continuous aerosol size distribution data has been collected at the SMEAR II station in a boreal forest in Hyytiälä, Finland, since 1996, making it the longest time series of aerosol size distributions available worldwide. In previous studies, the data have been classified as particle-formation event, nonevent, and undefined days, with almost 40% of the dataset classified as undefined. In the present study, eleven years (1996–2006 of undefined days (1630 days were reanalyzed and subdivided into three new classes: failed events (37% of all previously undefined days, ultrafine-mode concentration peaks (34%, and pollution-related concentration peaks (19%. Unclassified days (10% comprised the rest of the previously undefined days. The failed events were further subdivided into tail events (21%, where a tail of a formation event presumed to be advected to Hyytiälä from elsewhere, and quasi events (16% where new particles appeared at sizes 3–10 nm, but showed unclear growth, the mode persisted for less than an hour, or both. The ultrafine concentration peaks days were further subdivided into nucleation-mode peaks (24% and Aitken-mode peaks (10%, depending on the size range where the particles occurred. The mean annual distribution of the failed events has a maximum during summer, whereas the two peak classes have maxima during winter. The summer minimum previously found in the seasonal distribution of event days partially offsets a summer maximum in failed-event days. Daily-mean relative humidity and condensation sink values are useful in discriminating the new classes from each other. Specifically, event days had low values of relative humidity and condensation sink relative to nonevent days. Failed-event days

  1. Traffic restrictions in Beijing during the Sino-African Summit 2006: aerosol size distribution and visibility compared to long-term in situ observations

    Directory of Open Access Journals (Sweden)

    Y. F. Cheng

    2008-07-01

    Full Text Available Based on the long-term in-situ observations of aerosol particle number size distributions and meteorological parameters, the traffic restriction measures during the Sino-African Summit (4–6 November 2006 in Beijing, China have been found to be remarkably efficient in reducing the number concentration of aerosol particles, in particular Aitken and accumulation mode particles, and in improving the visibility. The influence of traffic restriction in Beijing on the particle concentrations differed for different particle sizes. More significant effects on fine particles with diameters ranging from 40 to 800 nm have been found. Based on statistical analysis of long-term observation, under comparable weather conditions, the source strength of the particles in Aitken and accumulation modes seemingly was reduced by 40–60% when the traffic restrictions were in place. It may be mainly due to the reduction of secondary particle formation. Our size-dependent aerosol data also indicate that measures led to reductions in particulate air pollution in the optically most important diameter range, whereas further vehicle control measures may lead to an increase in ultrafine particle formation from the gas phase if the condensational sink further decreased. Assuming that there were no traffic restrictions and with normal levels of the vehicle emissions, the visibilities during the Summit would have been lower by about 50%. The importance of the restrictions is highest when the wind speed is lower than 3 m s−1. The fact that over 95% cases with visual range lower than 5 km during 2004 to 2007 occurred when the local wind speed was lower than 3 m s−1 may suggest that future traffic restrictions will lead to significant improvements of visibility in Beijing.

  2. Measurements of Hygroscopicity- and Size-Resolved Sea Spray Aerosol

    Science.gov (United States)

    Phillips, B.; Dawson, K. W.; Royalty, T. M.; Reed, R. E.; Petters, M.; Meskhidze, N.

    2015-12-01

    Atmospheric aerosols play a central role in many environmental processes by influencing the Earth's radiative balance, tropospheric chemistry, clouds, biogeochemical cycles, and visibility as well as adversely impacting human health. Based on their origin, atmospheric aerosols can be defined as anthropogenic or natural. Recent studies have shown that a large fraction of uncertainty in the radiative effects of anthropogenic aerosols is related to uncertainty in natural—background—aerosols. Marine aerosols are of particular interest due to the abundance of oceans covering the Earth's surface. Despite their importance, limited information is currently available for size- and composition-resolved marine aerosol emission fluxes. Our group has designed and built an instrument for measuring the size- and hygroscopicity-resolved sea spray aerosol fluxes. The instrument was first deployed during spring 2015 at the end of the 560 m pier of the US Army Corps of Engineers' Field Research Facility in Duck, NC. Measurements include 200 nm-sized diameter growth factor (hygroscopicity) distributions, sea spray particle flux measurements, and total sub-micron sized aerosol concentration. Ancillary ocean data includes salinity, pH, sea surface temperature, dissolved oxygen content, and relative fluorescence (proxy for [Chl-a]). Hygroscopicity distribution measurements show two broad peaks, one indicative of organics and sulfates and another suggestive of sea salt. The fraction of 200 nm-sized salt particles having hygroscopicity similar to that of sea-spray aerosol contributes up to ~24% of the distribution on days with high-speed onshore winds and up to ~3% on calm days with winds blowing from the continent. However, the total concentration of sea-spray-like particles originating from offshore versus onshore winds was relatively similar. Changes in the relative contribution of sea-salt to number concentration were caused by a concomitant changes in total aerosol concentration

  3. Concentration and Size Distribution of Fungi Aerosol over Oceans along a Cruise Path during the Fourth Chinese Arctic Research Expedition

    Directory of Open Access Journals (Sweden)

    Zheng Li

    2013-11-01

    Full Text Available Bioaerosol can act as nuclei and thus may play an important role in climate change. During the Fourth Chinese National Arctic Research Expedition (CHINARE 2010 from July to September 2010, the concentrations and size distributions of airborne fungi, which are thought to be one of important bioaerosols, in the marine boundary layer were investigated. The concentrations of airborne fungi varied considerably with a range of 0 to 320.4 CFU/m3. The fungal concentrations in the marine boundary layer were significantly lower than those in most continental ecosystems. Airborne fungi over oceans roughly displayed a decreasing trend with increasing latitudes. The mean concentrations of airborne fungi in the region of offshore China, the western North Pacific Ocean, the Chukchi Sea, the Canada Basin, and the central Arctic Ocean were 172.2 ± 158.4, 73.8 ± 104.4, 13.3 ± 16.2, 16.5 ± 8.0, and 1.2 ± 1.0 CFU/m3, respectively. In most areas airborne fungi showed a unimodal size distribution pattern, with the maximum proportion (about 36.2% in the range of 2.1~3.3 µm and the minimum proportion (about 3.5% in the range of 0.65~1.1 µm, and over 50% occurred on the fine size (<3.3 µm. Potential factors influencing airborne fungal concentrations, including the origin of air mass, meteorological conditions, and sea ice conditions, were discussed.

  4. Observation of atmospheric aerosols at Mt. Hua and Mt. Tai in Central and East China during spring 2009 – Part 2: Impact of dust storm on organic aerosol composition and size distribution

    Directory of Open Access Journals (Sweden)

    J. J. Cao

    2011-12-01

    Full Text Available PM10 and size-resolved particles (9-stage were simultaneously collected at Mt. Hua and Mt. Tai in Central and East China during the spring of 2009 including a massive dust storm occurring on April 24th (named as DS II, and determined for organic compounds to investigate the impact of dust storm on organic aerosols. High molecular weight (HMW n-alkanes, fatty acids, and fatty alcohols and trehalose sharply increased and almost entirely stayed in coarse particles when dust storm was present, suggesting that high level of organic aerosols in the mountain atmospheres during the event originated from biogenic sources in the Gobi desert. However, most anthropogenic aerosols (e.g., PAHs, aromatic acids and dicarboyxlic acids during the event significantly decreased due to a dilution effect, indicating that anthropogenic aerosols in the mountain air during the nonevent period are largely derived from local/regional sources rather than from long-range transport. Our results indicate that trehalose can be taken as a new tracer for dust emissions from desert regions since trehalose was negligible in the nonevent but abundant in the event. Molecular compositions of organic aerosols in the mountain samples further demonstrate that domestic coal burning is still the major source of PAHs in China. n-Alkanes and fatty acids showed a bimodal size distribution during the nonevent with a major peak in fine mode (2.1 μm. The coarse mode significantly increased and even dominated over the whole size range when dust was present. Glucose and trehalose were also dominant in the coarse mode especially in the DS II time. PAHs and levoglucosan concentrated in fine particles with no significant changes in size distribution when dust storm occurred. However, phthalic and succinic acids showed bimodal size distribution pattern with an increase in coarse mode during the event, because both are formed via a gas phase oxidation and a subsequent condensation/adsorption onto

  5. [Aerosol size distribution of organic carbon and elemental carbon on the top of coke oven and in the plant area].

    Science.gov (United States)

    Liu, Xiao-Feng; Peng, Lin; Bai, Hui-Ling; Mu, Ling; Song, Chong-Fang

    2013-08-01

    In order to investigate the characteristic of organic carbon (OC) and elemental carbon (EC) in particles on the top of coke oven and in the plant area, the particle matter samples of five size fraction including or = 10.2 microm were collected using Staplex234 cascade impactor, and OC and EC were analyzed by Elementar Analysensysteme GmbH vario EL cube. The mass concentrations of OC and EC associated with TSP on the top of coke oven were 291.6 microg x m(-3) and 255.1 microg x m(-3), while those in the plant area were 377.8 microg x m(-3) and 151.7 microg x m(-3). The mass concentration of secondary organic carbon (SOC) in particles with size of coke oven. The mass concentration of EC in TSP in the plant area was lower than that on the top of coke oven, while the mass concentration of OC in the plant area was significantly higher than that on the top of coke oven. The mass concentrations of OC and EC associated with particles less than 10.2 microm in the plant area were far higher than those in the atmosphere of area where the coke plant is located. The OC and EC in particles, which were collected both on the top of coke oven and in the plant area, were mainly enriched in fine particles. The size distribution of OC showed a clear distinction between the coke oven top and the plant area, which revealed that OC in the plant area was more preferably enriched in fine particles than that on the top of coke oven, and the same size distribution of EC was found on the top of coke oven and in the plant area. In the plant area, the mass concentration of SOC and the contribution of SOC to OC increased with the decreasing diameter in particles with diameter of less than 10.2 microm. PMID:24191535

  6. Final Report, The Influence of Organic-Aerosol Emissions and Aging on Regional and Global Aerosol Size Distributions and the CCN Number Budget

    Energy Technology Data Exchange (ETDEWEB)

    Donahue, Neil M. [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2015-12-23

    We conducted laboratory experiments and analyzed data on aging of organic aerosol and analysis of field data on volatility and CCN activity. With supplemental ASR funding we participated in the FLAME-IV campaign in Missoula MT in the Fall of 2012, deploying a two-chamber photochemical aging system to enable experimental exploration of photochemical aging of biomass burning emissions. Results from that campaign will lead to numerous publications, including demonstration of photochemical production of Brown Carbon (BrC) from secondary organic aerosol associated with biomass burning emissions as well as extensive characterization of the effect of photochemical aging on the overall concentrations of biomass burning organic aerosol. Excluding publications arising from the FLAME-IV campaign, project research resulted in 8 papers: [11, 5, 3, 10, 12, 4, 8, 7], including on in Nature Geoscience addressing the role of organic compounds in nanoparticle growth [11

  7. Fluorescent biological aerosol particle concentrations and size distributions measured with an ultraviolet aerodynamic particle sizer (UV-APS in Central Europe

    Directory of Open Access Journals (Sweden)

    J. A. Huffman

    2009-08-01

    Full Text Available Primary biological aerosol particles (PBAPs, including bacteria, spores and pollen, are essential for the spread of organisms and disease in the biosphere, and numerous studies have suggested that they may be important for atmospheric processes, including the formation of clouds and precipitation. The atmospheric abundance and size distribution of PBAPs, however, are largely unknown. At a semi-urban site in Mainz, Germany, we used an ultraviolet aerodynamic particle sizer (UV-APS to measure fluorescent biological aerosol particles (FBAPs, which can be regarded as viable bioaerosol particles representing a lower limit for the actual abundance of PBAPs. Fluorescence of non-biological aerosol components are likely to influence the measurement results obtained for fine particles (<1 μm, but not for coarse particles (1–20 μm.

    Averaged over the four-month measurement period (August–December 2006, the mean number concentration of coarse FBAPs was ~3×10−2 cm−3, corresponding to ~4% of total coarse particle number. The mean mass concentration of FBAPs was ~1 μg m−3, corresponding to ~20% of total coarse particle mass. The FBAP number size distributions exhibited alternating patterns with peaks at various diameters. A pronounced peak at ~3 μm was essentially always observed and can be described by the following campaign-average lognormal fit parameters: geometric mean diameter 3.2 μm, geometric standard deviation 1.3, number concentration 1.6×10−2 cm−3. This peak is likely due to fungal spores or agglomerated bacteria, and it exhibited a pronounced diel cycle with maximum intensity during early/mid-morning. FBAP peaks around ~1.5 μm, ~5 μm, and ~13 μm were also observed, but less pronounced and less frequent. These may be explained by single bacterial cells, larger fungal spores, and pollen grains, respectively.

    The observed number concentrations and

  8. Fluorescent biological aerosol particle concentrations and size distributions measured with an Ultraviolet Aerodynamic Particle Sizer (UV-APS in Central Europe

    Directory of Open Access Journals (Sweden)

    J. A. Huffman

    2010-04-01

    Full Text Available Primary Biological Aerosol Particles (PBAPs, including bacteria, spores and pollen, are essential for the spread of organisms and disease in the biosphere, and numerous studies have suggested that they may be important for atmospheric processes, including the formation of clouds and precipitation. The atmospheric abundance and size distribution of PBAPs, however, are largely unknown. At a semi-urban site in Mainz, Germany we used an Ultraviolet Aerodynamic Particle Sizer (UV-APS to measure Fluorescent Biological Aerosol Particles (FBAPs, which provide an estimate of viable bioaerosol particles and can be regarded as an approximate lower limit for the actual abundance of PBAPs. Fluorescence of non-biological aerosol components are likely to influence the measurement results obtained for fine particles (<1 μm, but not for coarse particles (1–20 μm.

    Averaged over the four-month measurement period (August–December 2006, the mean number concentration of coarse FBAPs was ~3×10−2 cm−3, corresponding to ~4% of total coarse particle number. The mean mass concentration of FBAPs was ~1μg m−3, corresponding to ~20% of total coarse particle mass. The FBAP number size distributions exhibited alternating patterns with peaks at various diameters. A pronounced peak at ~3 μm was essentially always observed and can be described by the following campaign-average lognormal fit parameters: geometric mean diameter 3.2 μm, geometric standard deviation 1.3, number concentration 1.6×10−2 cm−3. This peak is likely due to fungal spores or agglomerated bacteria, and it exhibited a pronounced diel cycle (24-h with maximum intensity during early/mid-morning. FBAP peaks around ~1.5 μm, ~5 μm, and ~13 μm were also observed, but less pronounced and less frequent. These may be single bacterial cells, larger fungal spores, and pollen grains, respectively.

    The observed number

  9. Dynamics of Atmospheric Aerosol Number Size Distributions in the Eastern Mediterranean During the "SUB-AERO" Project.

    Czech Academy of Sciences Publication Activity Database

    Ždímal, Vladimír; Smolík, Jiří; Eleftheriadis, K.; Wagner, Zdeněk; Housiadas, Ch.; Mihalopoulos, N.; Mikuška, Pavel; Večeřa, Zbyněk; Kopanakis, I.; Lazaridis, M.

    2011-01-01

    Roč. 241, 1-4 (2011), s. 133-146. ISSN 0049-6979 Grant ostatní: SUBAERO(XE) EVK2-CT-1999O-00052 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40310501 Keywords : nucleation events * aerosols * particulate matter Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.625, year: 2011

  10. In situ measurements of aerosol optical properties and number size distributions in a coastal region of Norway during the summer of 2008

    Directory of Open Access Journals (Sweden)

    S. Mogo

    2012-07-01

    Full Text Available In situ measurements of aerosol optical properties and particle size distributions were made in the summer of 2008 at the ALOMAR station facility (69°16' N, 16°00' E, located in a rural site in the north of the island of Andøya (Vesterålen archipelago, approximately 300 km north of the Arctic Circle. The extended three-month campaign was part of the POLARCAT Project (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols, and Transport of the International Polar Year (IPY-2007-2008. Our goal was to characterize the aerosols of this sub-Arctic area, which are frequently transported to the Arctic region.

    Data from 13 June to 26 August 2008 were available and the statistical data for all instruments were calculated based on the hourly averages. The overall data coverage was approximately 72%. The hourly mean values of the light-scattering coefficient, σs, and the light-absorption coefficient, σa, at 550 nm were 5.41 Mm−1 (StD = 3.55 Mm−1 and 0.40 Mm−1 (StD = 0.27 Mm−1, respectively. The scattering/absorption Ångström exponents, αs,a, were used in a detailed analysis of the variations of the spectral shape of σs,a. While αs indicates the presence of two particle sizes corresponding to two types of aerosols, αa indicates only one type of absorbing aerosol particle. αa values greater than 1 were not observed. The single-scattering albedo, ω0, ranged from 0.62 to 0.99 (mean = 0.91, StD = 0.05, and the relationships between this parameter and the absorption/scattering coefficients and the Ångström exponents are presented. Any absorption value may lead to the lowest values of ω0, whereas only the lowest scattering values were observed in the lowest range of ω0. For a given absorption value, lower ω0 were

  11. Observation of aerosol size distribution and new particle formation at a mountain site in subtropical Hong Kong

    Directory of Open Access Journals (Sweden)

    H. Guo

    2012-05-01

    Full Text Available In order to investigate the atmospheric particle formation and growth processes, and to quantify the particle number (PN concentration and size distributions in Hong Kong, a three-month intensive field measurement was conducted from September to November in 2010 near the mountain summit of Tai Mo Shan, a suburban site approximately the geographical centre of the New Territories in Hong Kong. The mean total number concentration in the size range of 5.5–350 nm was 7.86 ± 0.66 × 103 cm−3 (mean ± 95% confidence interval, with a maximum value in November. New particle formation (NPF events were observed on 12 out of 35 days in October/November 2010 with the formation rate from 0.29 to 4.53 cm−3 s−1, and the average growth rates from 1.53 to 9.44 nm h−1. The events usually began at 10:00 ~ 11:00 local time characterized by the occurrence of a nucleation mode with a peak diameter of 6 ~ 10 nm. The observed linear or non-linear correlations between nucleation mode PN concentration (5.5–10 nm and ozone, volatile organic compounds (VOCs and/or (UV × SO2 suggested critical roles of sulfuric acid and biogenic VOCs (e.g. isoprene, α-pinene and β-pinene in the NPF events.

  12. Size distributions and temporal variations of biological aerosol particles in the Amazon rainforest characterized by microscopy and real-time UV-APS fluorescence techniques during AMAZE-08

    Directory of Open Access Journals (Sweden)

    J. A. Huffman

    2012-12-01

    Full Text Available As a part of the AMAZE-08 campaign during the wet season in the rainforest of central Amazonia, an ultraviolet aerodynamic particle sizer (UV-APS was operated for continuous measurements of fluorescent biological aerosol particles (FBAP. In the coarse particle size range (> 1 μm the campaign median and quartiles of FBAP number and mass concentration were 7.3 × 104 m−3 (4.0–13.2 × 104 m−3 and 0.72 μg m−3 (0.42–1.19 μg m−3, respectively, accounting for 24% (11–41% of total particle number and 47% (25–65% of total particle mass. During the five-week campaign in February–March 2008 the concentration of coarse-mode Saharan dust particles was highly variable. In contrast, FBAP concentrations remained fairly constant over the course of weeks and had a consistent daily pattern, peaking several hours before sunrise, suggesting observed FBAP was dominated by nocturnal spore emission. This conclusion was supported by the consistent FBAP number size distribution peaking at 2.3 μm, also attributed to fungal spores and mixed biological particles by scanning electron microscopy (SEM, light microscopy and biochemical staining. A second primary biological aerosol particle (PBAP mode between 0.5 and 1.0 μm was also observed by SEM, but exhibited little fluorescence and no true fungal staining. This mode may have consisted of single bacterial cells, brochosomes, various fragments of biological material, and small Chromalveolata (Chromista spores. Particles liquid-coated with mixed organic-inorganic material constituted a large fraction of observations, and these coatings contained salts likely from primary biological origin. We provide key support for the suggestion that real-time laser-induce fluorescence (LIF techniques using 355 nm excitation provide size-resolved concentrations of FBAP as a lower limit for the atmospheric abundance of biological particles in a pristine

  13. LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles – Part 1: Principle of measurements and instrument evaluation

    Directory of Open Access Journals (Sweden)

    J.-B. Renard

    2015-01-01

    Full Text Available The study of aerosols in the troposphere and in the stratosphere is of major importance both for climate and air quality studies. Among the numerous instruments available, aerosol particles counters provide the size distribution in diameter range from few hundreds of nm to few tens of μm. Most of them are very sensitive to the nature of aerosols, and this can result in significant biases in the retrieved size distribution. We describe here a new versatile optical particle/sizer counter (OPC named LOAC (Light Optical Aerosols Counter, which is light and compact enough to perform measurements not only at the surface but under all kinds of balloons in the troposphere and in the stratosphere. LOAC is an original OPC performing observations at two scattering angles. The first one is around 12°, and is almost insensitive to the nature of the particles; the second one is around 60° and is strongly sensitive to the refractive index of the particles. By combining measurement at the two angles, it is possible to retrieve accurately the size distribution and to estimate the nature of the dominant particles (droplets, carbonaceous, salts and mineral particles in several size classes. This speciation is based on calibration charts obtained in the laboratory. Several campaigns of cross-comparison of LOAC with other particle counting instruments and remote sensing photometers have been conducted to validate both the size distribution derived by LOAC and the retrieved particle number density. The speciation of the aerosols has been validated in well-defined conditions including urban pollution, desert dust episodes, fog, and cloud. Comparison with reference aerosol mass monitoring instruments also shows that the LOAC measurements can be successfully converted to mass concentrations. All these tests indicate that no bias is present in the LOAC measurements and in the corresponding data processing.

  14. Effect of Aerosol Size and Hygroscopicity on Aerosol Optical Depth in the Southeastern United States

    Science.gov (United States)

    Brock, Charles; Wagner, Nick; Gordon, Timothy

    2016-04-01

    Aerosol optical depth (AOD) is affected by the size, optical characteristics, and hygroscopicity of particles, confounding attempts to link remote sensing observations of AOD to measured or modeled aerosol mass concentrations. In situ airborne observations of aerosol optical, chemical, microphysical and hygroscopic properties were made in the southeastern United States in the daytime in summer 2013. We use these observations to constrain a simple model that is used to test the sensitivity of AOD to the various measured parameters. As expected, the AOD was found to be most sensitive to aerosol mass concentration and to aerosol water content, which is controlled by aerosol hygroscopicity and the ambient relative humidity. However, AOD was also fairly sensitive to the mean particle diameter and the width of the size distribution. These parameters are often prescribed in global models that use simplified modal parameterizations to describe the aerosol, suggesting that the values chosen could substantially bias the calculated relationship between aerosol mass and optical extinction, AOD, and radiative forcing.

  15. Sensitivity Analysis and Error Analysis of Reflectance Based Vicarious Calibration with Estimated Aerosol Refractive Index and Size Distribution Derived from Measured Solar Direct and Diffuse Irradiance as well as Measured Surface Reflectance

    Directory of Open Access Journals (Sweden)

    Kohei Arai

    2013-12-01

    Full Text Available Sensitivity analysis and error of reflectance based vicarious calibration with estimated aerosol refractive index and size distribution derived from measured solar direct and diffuse irradiance as well as measured surface reflectance is conducted for solar reflective channels of mission instruments onboard remote sensing satellites. Through these error analyses, it is found that the most influencing factor is surface reflectance. The most significant 75 to 91% of vicarious calibration coefficients error is due to surface reflectance followed by atmospheric optical depth and Junge parameter. Therefore, we have to care about surface reflectance measuring accuracy followed by atmospheric optical depth (aerosol refractive index, and water vapor and ozone absorption and Junge parameter (aerosol size distribution. As a conclusion, it is confirmed that surface reflectance is most influencing factor on TOA radiance. When the atmospheric optical depth is small, then Junge parameter is influencing.

  16. Submicron aerosols at thirteen diversified sites in China: size distribution, new particle formation and corresponding contribution to cloud condensation nuclei production

    Directory of Open Access Journals (Sweden)

    J. F. Peng

    2014-06-01

    Full Text Available Understanding the particle number size distributions in diversified atmospheric environments is important in order to design mitigation strategies related to submicron particles and their effect on regional air quality, haze and human health. In this study, we conducted 15 different field measurement campaigns, each one-month long, between 2007 and 2011 at 13 individual sites in China. These were 5 urban sites, 4 regional sites, 3 coastal/background sites and one ship cruise measurement along eastern coastline of China. Size resolved particles were measured in the 15–600 nm size range. The median particle number concentrations (PNC were found to vary in the range of 1.1–2.2 × 104 cm−3 at urban sites, 0.8–1.5 × 104 cm−3 at regional sites, 0.4–0.6 × 104 cm−3 at coastal/background sites, and 0.5 × 104 cm−3 during cruise measurements. Peak diameters at each of these sites varied greatly from 24 nm to 115 nm. Particles in the 15–25 nm (nucleation mode, 25–100 nm (Aitken mode and 100–600 nm (accumulation mode range showed different characteristics at each of the studied sites, indicating the features of primary emissions and secondary formation in these diversified atmospheric environments. Diurnal variations show a build-up of accumulation mode particles belt at regional sites, suggesting the contribution of regional secondary aerosol pollution. Frequencies of new particle formation (NPF events were much higher at urban and regional sites than at coastal sites and cruise measurement. The average growth rates (GRs of nucleation mode particles were 8.0–10.9 nm h−1 at urban sites, 7.4–13.6 nm h−1 at regional sites and 2.8–7.5 nm h−1 at both coastal and cruise measurement sites. The high gaseous precursors and strong oxidation at urban and regional sites not only favored the formation of particles, but also accelerated the growth rate of the nucleation mode particles. No significant difference in condensation sink

  17. Aerosol size distribution and new particle formation in the western Yangtze River Delta of China: 2 years of measurements at the SORPES station

    Science.gov (United States)

    Qi, X. M.; Ding, A. J.; Nie, W.; Petäjä, T.; Kerminen, V.-M.; Herrmann, E.; Xie, Y. N.; Zheng, L. F.; Manninen, H.; Aalto, P.; Sun, J. N.; Xu, Z. N.; Chi, X. G.; Huang, X.; Boy, M.; Virkkula, A.; Yang, X.-Q.; Fu, C. B.; Kulmala, M.

    2015-11-01

    Aerosol particles play important roles in regional air quality and global climate change. In this study, we analyzed 2 years (2011-2013) of measurements of submicron particles (6-800 nm) at a suburban site in the western Yangtze River Delta (YRD) of eastern China. The number concentrations (NCs) of particles in the nucleation, Aitken and accumulation modes were 5300 ± 5500, 8000 ± 4400, 5800 ± 3200 cm-3, respectively. The NCs of total particles are comparable to those at urban/suburban sites in other Chinese megacities, such as Beijing, but about 10 times higher than in the remote western China. Long-range and regional transport largely influenced number concentrations and size distributions of submicron particles. The highest and lowest accumulation-mode particle number concentrations were observed in air masses from the YRD and coastal regions, respectively. Continental air masses from inland brought the highest concentrations of nucleation-mode particles. New particle formation (NPF) events, apparent in 44 % of the effective measurement days, occurred frequently in all the seasons except winter. The frequency of NPF in spring, summer and autumn is much higher than other measurement sites in China. Sulfuric acid was found to be the main driver of NPF events. The particle formation rate was the highest in spring (3.6 ± 2.4 cm-3 s-1), whereas the particle growth rate had the highest values in summer (12.8 ± 4.4 nm h-1). The formation rate was typically high in relatively clean air masses, whereas the growth rate tended to be high in the polluted YRD air masses. The frequency of NPF events and the particle growth rates showed a strong year-to-year difference. In the summer of 2013, associated with a multi-week heat wave and strong photochemical processes, NPF events occurred with larger frequency and higher growth rates compared with the same period in 2012. The difference in the location and strength of the subtropical high pressure system, which influences

  18. Aerosol size distribution and new particle formation in western Yangtze River Delta of China: two-year measurement at the SORPES station

    Directory of Open Access Journals (Sweden)

    X. M. Qi

    2015-04-01

    Full Text Available Aerosol particles play important roles in regional air quality and global climate change. In this study, we analyzed two-year (2011–2013 of measurements of submicron particles (6–800 nm at a suburban site in western Yangtze River delta (YRD of East China. The number concentrations (NCs of particles in the nucleation, Aitken and accumulation modes were 5300 ± 5500, 8000 ± 4400, 5800 ± 3200 cm-3, respectively. Number concentrations and size distributions of submicron particles were also influenced by long-range and regional transport of air masses. The highest and lowest accumulation mode particle number concentrations were observed in air masses from YRD and coastal region, respectively. Continental air masses from inland had the highest concentrations of nucleation mode particles. New particle formation (NPF events, apparent in 44% of the effective measurement days, occurred frequently in all the seasons except winter. Radiation and pre-existing particles were found to be the main factors influencing the occurrence of NPF events. The particle formation rate was the highest in spring (3.6 ± 2.4 cm-3 s-1, whereas the particle growth rate had the highest values in summer (12.8 ± 4.4 nm h-1. The formation rate was typically high in relatively clean air masses, whereas the growth rate tended to be high in the polluted YRD air masses. The frequency of NPF events and the growth rate showed a strong year-to-year difference. In the summer of 2013, associated with a multi-week heat wave and photochemical pollution, NPF events occurred more frequently and the growth rate was much higher than in the same period of 2012. The difference in the location and strength of sub-tropical High, which influences the air mass transport pathways and solar radiation, seems to be the driving cause for year-to-year differences. This study reported the longest continuous measurement records of submicron particles in the East China and gained a comprehensive

  19. Submicron aerosols at thirteen diversified sites in China: size distribution, new particle formation and corresponding contribution to cloud condensation nuclei production

    Science.gov (United States)

    Peng, J. F.; Hu, M.; Wang, Z. B.; Huang, X. F.; Kumar, P.; Wu, Z. J.; Guo, S.; Yue, D. L.; Shang, D. J.; Zheng, Z.; He, L. Y.

    2014-09-01

    Understanding the particle number size distributions in diversified atmospheric environments is important in order to design mitigation strategies related to submicron particles and their effects on regional air quality, haze and human health. In this study, we conducted 15 different field measurement campaigns between 2007 and 2011 at 13 individual sites in China, including five urban sites, four regional sites, three coastal/background sites and one ship cruise measurement along eastern coastline of China. Size resolved particles were measured in the 15-600 nm size range. The median particle number concentrations (PNCs) were found to vary in the range of 1.1-2.2 × 104 cm-3 at urban sites, 0.8-1.5 × 104 cm-3 at regional sites, 0.4-0.6 × 104 cm-3 at coastal/background sites, and 0.5 × 104 cm-3 during cruise measurement. Peak diameters at each of these sites varied greatly from 24 to 115 nm. Particles in the 15-25 nm (nucleation mode), 25-100 nm (Aitken mode) and 100-600 nm (accumulation mode) range showed different characteristics at each sites, indicating the features of primary emissions and secondary formation in these diversified atmospheric environments. Diurnal variations show a build-up of accumulation mode particles belt at regional sites, suggesting the contribution of regional secondary aerosol pollution. Frequencies of new particle formation (NPF) events were much higher at urban and regional sites than at coastal sites and during cruise measurement. The average growth rates (GRs) of nucleation mode particles were 8.0-10.9 nm h-1 at urban sites, 7.4-13.6 nm h-1 at regional sites and 2.8-7.5 nm h-1 at coastal sites and during cruise measurement. The high gaseous precursors and strong oxidation at urban and regional sites not only favored the formation of particles, but also accelerated the growth rate of the nucleation mode particles. No significant difference in condensation sink (CS) during NPF days were observed among different site types

  20. Size distributions of aerosol sulfates and nitrates in Beijing during the 2008 Olympic Games: Impacts of pollution control measures and regional transport

    Science.gov (United States)

    Wang, Xinfeng; Wang, Tao; Pathak, Ravi Kant; Hallquist, Mattias; Gao, Xiaomei; Nie, Wei; Xue, Likun; Gao, Jian; Gao, Rui; Zhang, Qingzhu; Wang, Wenxing; Wang, Shulan; Chai, Fahe; Chen, Yizhen

    2013-03-01

    For the 2008 Olympic Games, drastic control measures were implemented on industrial and urban emissions of sulfur dioxide (SO2), nitrogen oxides (NO x ) and other pollutants to address the issues of poor air quality in Beijing. To investigate the effects of SO2 and NO x reductions on the particulate sulfate and nitrate concentrations as well as their size distributions, size-segregated aerosol samples were collected using micro-orifice uniform deposit impactors (MOUDIs) at urban and downwind rural sites in Beijing before and after full-scale controls. During the sampling period, the mass concentrations of fine particles (PM1.8) at the urban and rural sites were 94.0 and 85.9 μg m-3, respectively. More than 90% of the sulfates and ˜60% of nitrates formed as fine particles. Benefiting from the advantageous meteorological conditions and the source controls, sulfates were observed in rather low concentrations and primarily in condensation mode during the Olympics. The effects of the control measures were separately analyzed for the northerly and the southerly air-mass-dominated days to account for any bias. After the control measures were implemented, PM, sulfates, and nitrates were significantly reduced when the northerly air masses prevailed, with a higher percentage of reduction in larger particles. The droplet mode particles, which dominated the sulfates and nitrates before the controls were implemented, were remarkably reduced in mass concentration after the control measures were implemented. Nevertheless, when the polluted southerly air masses prevailed, the local source control measures in Beijing did not effectively reduce the ambient sulfate concentration due to the enormous regional contribution from the North China Plain.

  1. Size Distributions of Aerosol Sulfates and Nitrates in Beijing during the 2008 Olympic Games: Impacts of Pollution Control Measures and Regional Transport

    Institute of Scientific and Technical Information of China (English)

    WANG Xinfeng; WANG Tao; Ravi Kant PATHAK; Mattias HALLQUIST; GAO Xiaomei; NIE Wei; XUE Likun

    2013-01-01

    For the 2008 Olympic Games,drastic control measures were implemented on industrial and urban emissions of sulfur dioxide (SO2),nitrogen oxides (NOx) and other pollutants to address the issues of poor air quality in Beijing.To investigate the effects of SO2 and NOx reductions on the particulate sulfate and nitrate concentrations as well as their size distributions,size-segregated aerosol samples were collected using micro-orifice uniform deposit impactors (MOUDIs) at urban and downwind rural sites in Beijing before and after full-scale controls.During the sampling period,the mass concentrations of fine particles (PM1.8) at the urban and rural sites were 94.0 and 85.9 μg m-3,respectively.More than 90% of the sulfates and ~60%of nitrates formed as fine particles.Benefiting from the advantageous meteorological conditions and the source controls,sulfates were observed in rather low concentrations and primarily in condensation mode during the Olympics.The effects of the control measures were separately analyzed for the northerly and the southerly air-mass-dominated days to account for any bias.After the control measures were implemented,PM,sulfates,and nitrates were significantly reduced when the northerly air masses prevailed,with a higher percentage of reduction in larger particles.The droplet mode particles,which dominated the sulfates and nitrates before the controls were implemented,were remarkably reduced in mass concentration after the control measures were implemented.Nevertheless,when the polluted southerly air masses prevailed,the local source control measures in Beijing did not effectively reduce the ambient sulfate concentration due to the enormous regional contribution from the North China Plain.

  2. On the sub-micron aerosol size distribution in a coastal-rural site at El Arenosillo Station (SW-Spain

    Directory of Open Access Journals (Sweden)

    M. Sorribas

    2011-02-01

    Full Text Available This study is focused on the analysis of the sub-micron aerosol characteristics at rural and coastal environment in Southwestern Spain. Particle number size distributions were measured in the size range (14–673 nm using a Scanning Mobility Particle Sizer (SMPS, Model 3936-TSI, from 15 July 2004 to 31 July 2006 at El Arenosillo Station. Mean total concentration was 8660 cm−3 and mean concentrations for the nucleation, Aitken and accumulation modes particles were 2830 cm−3, 4110 cm−3 and 1720 cm−3, respectively. Mean geometric diameters of the four modes particles, which characterized the mean size distribution per month, were about 16 nm, 42 nm, 103 nm and 237 nm. Two kinds of episodes produced a maximum of the total concentration around noon: the new particle formation and the regional recirculation such as the sea-land breeze. Two types of nucleation events (called N$1 and N2 were observed. Events N1 were an example of the influence of regional sources and Events N2 showed the weight of local industries over the rural and coastal background levels. The 60% of nucleation events were related to NE and NW wind sectors (N1 and N2 respectively, a ΔT higher than 12 °C, a wind speed higher than 2.3 m s−1 and a total surface area for the accumulation mode particles below of 11 190 μ m2 cm−3. The influence of the sea-land breeze processes has been analyzed, observing increases of up to 50%, 110% and 90% of the particle concentration for the nucleation, Aitken and accumulation modes. Annual evolution of monthly averages allowed to conclude that the increase or decrease of 1 cm−3 of the concentration for nucleation mode particles was related to opposite trend of 0.5 cm−3 of the concentration for accumulation mode. This anti-correlation produced a weak seasonal

  3. On the sub-micron aerosol size distribution in a coastal-rural site at El Arenosillo Station (SW – Spain

    Directory of Open Access Journals (Sweden)

    M. Sorribas

    2011-11-01

    Full Text Available This study focuses on the analysis of the sub-micron aerosol characteristics at El Arenosillo Station, a rural and coastal environment in South-western Spain between 1 August 2004 and 31 July 2006 (594 days. The mean total concentration (NT was 8660 cm−3 and the mean concentrations in the nucleation (NNUC, Aitken (NAIT and accumulation (NACC particle size ranges were 2830 cm−3, 4110 cm−3 and 1720 cm−3, respectively. Median size distribution was characterised by a single-modal fit, with a geometric diameter, median number concentration and geometric standard deviation of 60 nm, 5390 cm−3 and 2.31, respectively. Characterisation of primary emissions, secondary particle formation, changes to meteorology and long-term transport has been necessary to understand the seasonal and annual variability of the total and modal particle concentration. Number concentrations exhibited a diurnal pattern with maximum concentrations around noon. This was governed by the concentrations of the nucleation and Aitken modes during the warm seasons and only by the nucleation mode during the cold seasons. Similar monthly mean total concentrations were observed throughout the year due to a clear inverse variation between the monthly mean NNUC and NACC. It was related to the impact of desert dust and continental air masses on the monthly mean particle levels. These air masses were associated with high values of NACC which suppressed the new particle formation (decreasing NNUC. Each day was classified according to a land breeze flow or a synoptic pattern influence. The median size distribution for desert dust and continental aerosol was dominated by the Aitken and accumulation modes, and marine air masses were dominated by the nucleation and Aitken modes. Particles

  4. Seasonal variations of aerosol size distributions based on long-term measurements at the high altitude Himalayan site of Nepal Climate Observatory-Pyramid (5079 m, Nepal

    Directory of Open Access Journals (Sweden)

    K. Sellegri

    2010-11-01

    Full Text Available The present paper investigates the diurnal and seasonal variability of the aerosol total number concentration, number and volume size distribution between 10 nm and 10 μm, from a combination of a scanning mobility particle sizer (SMPS and an optical counter (OPC, performed over a two-year period (January 2006–February 2008 at the Nepal Climate Observatory-Pyramid (NCO-P research station, (5079 m a.s.l.. The annual average number concentration measured over the two-year period at the NCO-P is 860 cm−3. Total concentrations show a strong seasonality with maxima during pre-monsoon and post-monsoon seasons and minima during the dry and monsoon seasons. A diurnal variation is also clearly observed, with maxima between 09:00 and 12:00 UTC. The aerosol concentration maxima are mainly due to nucleation processes during the post-monsoon season, as witnessed by high nucleation mode integrated number concentrations, and to transport of high levels of pollution from the plains by valley breezes during the pre-monsoon season, as demonstrated by high accumulation mode integrated number concentrations. Night-time number concentration of particles (from 03:00 to 08:00 NST are relatively low throughout the year (from 450 cm−3 during the monsoon season to 675 cm−3 during the pre-monsoon season, indicating the of high altitudes background level, as a result of downslope winds during this part of the day. However, it was found that these background concentrations are strongly influenced by the daytime concentrations, as they show the same seasonal variability. If nighttime concentrations were presumed to be representative of free troposphere (FT/residual layer concentrations, they would be found to be two times higher than at other lower altitudes European sites, such as the Jungfraujoch. However, BL intrusions might contaminate the free troposphere/residual layer even at this altitude, especially during regional air masses

  5. LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles - Part 1: Principle of measurements and instrument evaluation

    Science.gov (United States)

    Renard, Jean-Baptiste; Dulac, François; Berthet, Gwenaël; Lurton, Thibaut; Vignelles, Damien; Jégou, Fabrice; Tonnelier, Thierry; Jeannot, Matthieu; Couté, Benoit; Akiki, Rony; Verdier, Nicolas; Mallet, Marc; Gensdarmes, François; Charpentier, Patrick; Mesmin, Samuel; Duverger, Vincent; Dupont, Jean-Charles; Elias, Thierry; Crenn, Vincent; Sciare, Jean; Zieger, Paul; Salter, Matthew; Roberts, Tjarda; Giacomoni, Jérôme; Gobbi, Matthieu; Hamonou, Eric; Olafsson, Haraldur; Dagsson-Waldhauserova, Pavla; Camy-Peyret, Claude; Mazel, Christophe; Décamps, Thierry; Piringer, Martin; Surcin, Jérémy; Daugeron, Daniel

    2016-04-01

    The study of aerosols in the troposphere and in the stratosphere is of major importance both for climate and air quality studies. Among the numerous instruments available, optical aerosol particles counters (OPCs) provide the size distribution in diameter range from about 100 nm to a few tens of µm. Most of them are very sensitive to the nature of aerosols, and this can result in significant biases in the retrieved size distribution. We describe here a new versatile optical particle/sizer counter named LOAC (Light Optical Aerosol Counter), which is light and compact enough to perform measurements not only at the surface but under all kinds of balloons in the troposphere and in the stratosphere. LOAC is an original OPC performing observations at two scattering angles. The first one is around 12°, and is almost insensitive to the refractive index of the particles; the second one is around 60° and is strongly sensitive to the refractive index of the particles. By combining measurement at the two angles, it is possible to retrieve the size distribution between 0.2 and 100 µm and to estimate the nature of the dominant particles (droplets, carbonaceous, salts and mineral particles) when the aerosol is relatively homogeneous. This typology is based on calibration charts obtained in the laboratory. The uncertainty for total concentrations measurements is ±20 % when concentrations are higher than 1 particle cm-3 (for a 10 min integration time). For lower concentrations, the uncertainty is up to about ±60 % for concentrations smaller than 10-2 particle cm-3. Also, the uncertainties in size calibration are ±0.025 µm for particles smaller than 0.6 µm, 5 % for particles in the 0.7-2 µm range, and 10 % for particles greater than 2 µm. The measurement accuracy of submicronic particles could be reduced in a strongly turbid case when concentration of particles > 3 µm exceeds a few particles cm-3. Several campaigns of cross-comparison of LOAC with other particle counting

  6. Endotoxin in Size-Separated Metal Working Fluid Aerosol Particles.

    Science.gov (United States)

    Dahlman-Höglund, Anna; Lindgren, Åsa; Mattsby-Baltzer, Inger

    2016-08-01

    Patients with airway symptoms working in metal working industries are increasing, despite efforts to improve the environmental air surrounding the machines. Our aim was to analyse the amount of endotoxin in size-separated airborne particles of metal working fluid (MWF) aerosol, by using the personal sampler Sioutas cascade impactor, to compare filter types, and to compare the concentration of airborne endotoxin to that of the corresponding MWFs. In a pilot field study, aerosols were collected in two separate machine halls on totally 10 occasions, using glass fibre and polytetrafluoroethylene (PTFE) filters in parallel at each station. Airborne endotoxin was distributed over all size fractions. While a major part was found in the largest size fraction (72%, 2.5-10 µm), up to 8% of the airborne endotoxin was detected in the smallest size fraction (efficiency of the filter types, a significantly higher median endotoxin level was found with glass fibres filters collecting the largest particle-size fraction (1.2-fold) and with PTFE filters collecting the smallest ones (5-fold). The levels of endotoxin in the size-separated airborne particle fractions correlated to those of the MWFs supporting the aerosol-generating machines. Our study indicates that a significant part of inhalable aerosols of MWFs consists of endotoxin-containing particles below the size of intact bacteria, and thus small enough to readily reach the deepest part of the lung. Combined with other chemical irritants of the MWF, exposure to MWF aerosols containing endotoxin pose a risk to respiratory health problems. PMID:27268595

  7. Nanometer aerosol size analyzer (nASA) and data inversion

    Science.gov (United States)

    Han, Hee Siew

    A fast-response Nanometer Aerosol Size Analyzer (nASA) that is capable of scanning 30 size channels between 3 and 100 nm in a total time of 3 seconds was developed. The analyzer includes a bipolar charger (Po 210), an extended-length Nano DMA, and an electrometer. This combination of components provides particle size spectra at a scan rate of 0.1 second per channel free of uncertainties caused by response-time induced smearing. In addition, because of its thermodynamically stable means of particle detection, the nASA is useful for applications requiring measurements over a broad range of sample pressures and temperatures. Indeed, experimental transfer functions determined for the extended-length Nano-DMA using the Tandem Differential Mobility Analyzer technique indicate the nASA provides good size resolution at pressures as low as 200 Torr, corresponding to measurement at an altitude of 10 km. The second part of this study is devoted to the selection of an accurate data inversion algorithm. From the simulation results, it is found that MICRON provides the most stable solutions with good accuracy and reasonable convergent speed especially when aerosol distribution functions are bi-modal. All subsequent nASA measurement results are inverted using the MICRON algorithm. A second generation nASA was developed for the later series of engine exhaust measurements. Several improvements are implemented to the nASA to enhance its performance and ease of use. First, its physical size is reduced and the capability for controlling the DMA flow rates via computer software is added. The former improves the portability of the instrument and the latter allows the nASA to have an wider aerosol size ranges. Finally, the system was used in the EXperiment to Characterize Aircraft Volatile Aerosol and Trace species Emissions (EXCAVATE) workshop to investigate aerosol size distribution from a Boeing 757 engine. The results show that the aerosol size distributions from the engine are

  8. Investigating Chemical and Thermodynamic Conditions that Determine the Aerosol Inorganic Nitrate Size Distribution: Insights from Speciated PM2.5 and PM10 Hourly Datasets from an Urban Site

    Science.gov (United States)

    Griffith, S. M.; Huang, X. H. H.; Louie, P. K. K.; Yu, J. Z.

    2015-12-01

    Nitric acid (HNO3), the gas-phase precursor to aerosol nitrate is known to rapidly transfer to aerosols where NH4+ is in excess to SO42- present in the aerosol, but the HNO3 is also subject to the slower uptake onto sea salt and dust laden particles. Understanding the competition between these routes is necessary to predict the NO3- distribution and impact on aerosols. In this study, we investigated the conditions leading to predominant fine or coarse mode aerosol nitrate using an hourly MARGA 2S dataset from an urban site in Hong Kong. The hourly dataset of inorganic ions (SO42-, NH4+, NO3-, Na+, Cl-, Ca2+, K+, Mg2+) in 2 size ranges (fine, trove for analyzing aerosol nitrate chemistry and the underlying mechanisms that ultimately determine the fraction of NO3- in the fine mode. The urban site in this study is initially characterized for seasonal environmental conditions and the aerosol chemical composition. The relationship between excess NH4+ and NO3- in the fine mode is detailed and contrasted with the influence on fine mode NO3- from uptake on sea salt and dust, which is typically relegated as a 'coarse-mode' mechanism. The distribution of NO3- in the fine and coarse modes is compared with the distribution of the other inorganic ions, where sea-salt ion (Na+, Mg2+) distributions yield the highest explained variability for the nitrate distributions. As a complement to that finding, the cation equivalency (excluding NH4+) in the coarse mode proves to be a crucial factor in leveraging the distribution away from fine mode nitrate. The uptake potential of the water-soluble gases is used to drive a mass transfer model and compare with thermodynamic equilibrium results. In the modeling, the partitioning cycles of fine and coarse mode aerosol nitrate highlight the dynamic relationship between NO3- and Cl- in both the fine and coarse modes, where the replacement of Cl- with NO3- is much faster in the fine mode due to shorter mass transfer time scales and more efficient

  9. Size Resolved Chemical Composition of Atmospheric Aerosol at Urban and Suburban Sites at Central European Air Pollution Hot Spot

    Czech Academy of Sciences Publication Activity Database

    Schwarz, Jaroslav; Ondráček, Jakub; Ondráčková, Lucie; Kozáková, Jana; Hovorka, J.; Ždímal, Vladimír

    -: Italian Aerosol Society, 2015. ISBN N. [European Aerosol Conference EAC 2015. Milano (IT), 06.09.2015-11.09.2015] R&D Projects: GA ČR(CZ) GBP503/12/G147 Institutional support: RVO:67985858 Keywords : mass size distribution * size resolved chemical composition * urban aerosol Subject RIV: DN - Health Impact of the Environment Quality

  10. Size Dependence of Incorporation of Gas Molecules into Aerosol Nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Levdansky, V.V.; Smolík, Jiří; Ždímal, Vladimír; Moravec, Pavel

    Prague : Czech Aerosol Society , 2013, C027. ISBN N. [European Aerosol Conference (EAC 2013). Prague (CZ), 01.09.2013-06.09.2013] R&D Projects: GA AV ČR IAA200760905 Institutional support: RVO:67985858 Keywords : aerosol * nanoparticles * size effect Subject RIV: CF - Physical ; Theoretical Chemistry http://eac2013.cz/index.php

  11. Chemical composition and size distribution of summertime PM2.5 at a high altitude remote location in the northeast of the Qinghai-Xizang (Tibet) Plateau: insights into aerosol sources and processing in free troposphere

    Science.gov (United States)

    Xu, J. Z.; Zhang, Q.; Wang, Z. B.; Yu, G. M.; Ge, X. L.; Qin, X.

    2015-05-01

    Aerosol filter samples were collected at a high-elevation mountain observatory (4180 m a.s.l.) in the northeastern part of the Qinghai-Xizang (Tibet) Plateau (QXP) during summer 2012 using a low-volume sampler and a micro-orifice uniform deposit impactor (MOUDI). These samples were analyzed for water-soluble inorganic ions (WSIs), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and total organic nitrogen (TON) to elucidate the size-resolved chemical composition of free tropospheric aerosols in the QXP region. The average mass concentration of the sum of the analyzed species in PM2.5 (particle matter) (WSIs + OC + EC + TON) was 3.74 μg sm-3, 36% of which was sulfate, 18% OC, 17 % nitrate, 10% ammonium, 6.6% calcium, 6.4% TON, 2.6% EC, 1.5 % sodium, 0.9% chloride, 0.5% magnesium, and 0.3% potassium. The size distributions of sulfate and ammonium peaked in the accumulation mode (0.32-0.56 μm), whereas the size distributions of both nitrate and calcium peaked in the range of 1.8-3.2 μm, suggesting the formation of nitrate on mineral dust. OC, EC and TON were also predominantly found in the accumulation mode. The bulk chemical composition and the average oxidation degree of water-soluble organic matter (WSOM) were assessed using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). WSOM was found to be highly oxidized in all PM2.5 samples with an average oxygen-to-carbon atomic ratio (O / C) of 1.16 and an organic mass-to-organic carbon ratio (OM / OC) of 2.75. The highly oxidized WSOM was likely related to active cloud processing during upslope air mass transport coupled with strongly oxidizing environments caused by snow/ice photochemistry. High average ratios of OC / EC (7.6) and WSOC / OC (0.79) suggested that organic aerosols were primarily made of secondary species. Secondary organic aerosol (SOA) was estimated on average accounting for 80% (62-96%) of the PM2.5, indicating that SOA is an important component

  12. INTEGRATING NEPHELOMETER RESPONSE CORRECTIONS FOR BIMODAL SIZE DISTRIBUTIONS

    Science.gov (United States)

    Correction factors are calculated for obtaining true scattering extinction coefficients from integrating nephelometer measurements. The corrections are based on the bimodal representation of ambient aerosol size distributions, and take account of the effects of angular truncation...

  13. Size-Resolved Volatility and Chemical Composition of Aged European Aerosol Measured During FAME-2008

    Science.gov (United States)

    Hildebrandt, L.; Mohr, C.; Lee, B.; Engelhart, G. J.; Decarlo, P. F.; Prevot, A. S.; Baltensperger, U.; Donahue, N. M.; Pandis, S. N.

    2008-12-01

    We present first results on the volatility and chemical composition of aged organic aerosol measured during the Finokalia Aerosol Measurement Experiment - 2008 (FAME-2008). Finokalia is located in the Southeast of Crete, Greece, and this remote site allows for the measurement of aged European aerosol as it is transported from Central to Southeastern Europe. We measured the volatility of the aerosol at Finokalia as a function of its size by combining several instruments. We used an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) to measure the size-resolved chemical composition of the particles, a scanning mobility particle sizer (SMPS) to measure the volume distribution of particles, and a thermodenuder system to induce changes in size and composition via moderate heating of the particles. The largest fraction of the non-refractory material in the aerosol sampled was ammonium sulfate and ammonium bisulfate, followed by organic material and a small contribution from nitrate. Most of the organic aerosol was highly oxidized, even after only a few days of transport over continental Europe. These highly oxidized organics had lower volatility than fresh primary or secondary aerosol measured in the laboratory. Significant changes in air-parcel trajectories and wind direction led to changes in the chemical composition of the sampled aerosol and corresponding changes of the volatility. These results allow the quantification of the effect of atmospheric processing on organic aerosol volatility and can be used as constraints for atmospheric Chemical Transport Models that predict the aerosol volatility.

  14. Concentration, distribution and variation of polar organic aerosol tracers in Ya'an, a middle-sized city in western China

    Science.gov (United States)

    Li, Li; Dai, Dongjue; Deng, Shihuai; Feng, Jialiang; Zhao, Min; Wu, Jun; Liu, Lu; Yang, Xiaohui; Wu, Sishi; Qi, Hui; Yang, Gang; Zhang, Xiaohong; Wang, Yingjun; Zhang, Yanzong

    2013-02-01

    PM2.5 (particulate matter with an aerodynamic diameter aerosol samples were collected in Ya'an, a middle-sized city with extensive wood resources in Southwestern China, to characterize the contribution of secondary organic aerosols (SOA) to the regional troposphere, the composition of the organic tracers as well as factors affecting their concentrations. A total of 34 samples were gathered on the Campus of Sichuan Agricultural University (SAU, urban site, in the city zone of Ya'an), while 49 samples were collected at Baima Spring Scenic Area (BSSA, forest site, situated about 30 km to the northeast of SAU) during June to July, 2010. Using GC/MS analysis with prior trimethylsilylation, organic tracers including isoprene oxidation products (2-methyltetrols, C5-alkene triols and 2-methylglyceric acid), α-/β-pinene oxidation products (norpinic acid, 3-hydroxyglutaric acid, 3-hydroxy-4,4-dimethylglutaric acid, and 3-methyl-1,2,3- butanetricarboxylic acid), a sesquiterpene oxidation product (β-caryophyllinic acid), sugars (glucose and fructose), sugar alcohols (arabitol, mannitol, erythritol, sorbitol and xylitol), anhydrosugars (levoglucosan, mannosan and galactosan) and malic acid were determined. The factors that could potentially affect the SOA tracer concentrations, i.e. trace gases (SO2, NOx, O3, NH3), aerosol acidity and meteorological parameters, were monitored. The results showed that the concentrations of total isoprene oxidation products were 72 and 82 ng/m3 at the two sampling locations, with 29 ± 18, 37 ± 9, 6 ± 2 ng/m3 at SAU and 57 ± 34, 33 ± 33, 4 ± 2 ng/m3 at BSSA for 2-methyltetrols, C5-alkene triols and 2-methylglyceric acid respectively. Compared with the concentrations of isoprene oxidation products, those of α-/β-pinene oxidation products and β-caryophyllinic acid were much lower, being 6 ± 33 and 0.5 ± 1.9 ng/m3 at SAU, and 9 ± 14 and 1.0 ± 1.2 ng/m3 at BSSA, respectively. The unique composition of isoprene oxidation products

  15. Characterization of Size-Fractionated Atmospheric Aerosol Collected in the Eastern Mediterranean Region

    Czech Academy of Sciences Publication Activity Database

    Smolík, Jiří; Ždímal, Vladimír; Eleftheriadis, K.; Havránek, Vladimír; Mihalopoulos, N.; Schwarz, Jaroslav; Colbeck, I.; Lazaridis, M.

    Vol. 56. Helsinki: University of Helsinki, 2002 - (Korhonen, H.), s. 142-145 ISBN 952-5027-34-1. [Czech-Finnish Aerosol Symposium. Prague (CZ), 23.05.2002-26.05.2002] Grant ostatní: EVK2(XE) CT/1999/00052 Keywords : atmospheric aerosols * mass size distribution * elemental and Ionic composition Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  16. Size-segregated aerosol mass closure and chemical composition in Monte Cimone (I during MINATROC

    Directory of Open Access Journals (Sweden)

    J.-P. Putaud

    2003-07-01

    Full Text Available Physical and chemical characterizations of the atmospheric aerosol was carried out at Mt. Cimone (Italy during the 4 June–4 July 2000 period. Particle size distributions in the size range 6 nm–10 μm were measured with a differential mobility analyzer (DMA and a optical particle counter (OPC. Size-segregated aerosol was sampled using a 6-stage low pressure impactor. Aerosol samples were submitted to gravimetric and chemical analyses. Ionic, carbonaceous and refractory components of the aerosol were quantified. We compared the sub- and super-μm aerosol mass concentrations determined by gravimetric measurements (mGM, chemical analyses (mCA, and by converting particle size distribution to aerosol mass concentrations (mSC. Mean random uncertainties associated with the determination of mGM, mCA, and mSD were assessed. The three estimates of the sub-μm aerosol mass concentration agreed, which shows that within experimental uncertainty, the sub-μm aerosol was composed of the quantified components. The three estimates of the super-mm aerosol mass concentration did not agree, which indicates that random uncertainties and/or possible systematic errors in aerosol sampling, sizing or analyses were not adequately accounted for. Aerosol chemical composition in air masses from different origins showed differences, which were significant in regard to experimental uncertainties. During the Saharan dust advection period, coarse dust and fine anthropogenic particles were externally mixed. No anthropogenic sulfate could be found in the super-μm dust particles. In contrast, nitrate was shifted towards the aerosol super-μm fraction in presence of desert dust.

  17. Measurement of resuspended aerosol in the Chernobyl area. Pt. III. Size distribution and dry deposition velocity of radioactive particles during anthropogenic enhanced resuspension

    International Nuclear Information System (INIS)

    During anthropogenic activities, such as agricultural soil management and traffic on unpaved roads, size distribution measurements were performed of atmospheric particulate radionuclides at a site in the Chernobyl 30-km exclusion zone. Analysis of cascade impactor measurements showed an increase of the total atmospheric radioactivity. In the cases of harrowing by a tractor and traffic on unpaved roads, a common shape of the size distribution was found with two maxima, the first in the 2-4 μm range, the second in the 12-20 μm range. The size distributions were compared to measurements during wind-driven resuspension. Particle number concentration measurements with an Aerodynamic Particle Sizer showed a dynamic dependence of the particle concentration in different size ranges on anthropogenic action. The increase of the mean concentration was for the large particles more than one order of magnitude higher than for fine particles during anthropogenic enhanced resuspension. From the measurement of the mass concentration, the radioactive loading could be estimated. An enrichment of radionuclides on resuspended particles (compared to soil particles) was found, with the highest enrichment for large particles. Micrometeorological considerations showed that large particles may frequently be subject to medium range transport. The dry deposition velocity was measured; the mean value of 0.026 m s-1±0.016 m s-1 is typical for 6-9 μm diameter particles. (orig.)

  18. Measurement of nonvolatile particle number size distribution

    Science.gov (United States)

    Gkatzelis, G. I.; Papanastasiou, D. K.; Florou, K.; Kaltsonoudis, C.; Louvaris, E.; Pandis, S. N.

    2016-01-01

    An experimental methodology was developed to measure the nonvolatile particle number concentration using a thermodenuder (TD). The TD was coupled with a high-resolution time-of-flight aerosol mass spectrometer, measuring the chemical composition and mass size distribution of the submicrometer aerosol and a scanning mobility particle sizer (SMPS) that provided the number size distribution of the aerosol in the range from 10 to 500 nm. The method was evaluated with a set of smog chamber experiments and achieved almost complete evaporation (> 98 %) of secondary organic as well as freshly nucleated particles, using a TD temperature of 400 °C and a centerline residence time of 15 s. This experimental approach was applied in a winter field campaign in Athens and provided a direct measurement of number concentration and size distribution for particles emitted from major pollution sources. During periods in which the contribution of biomass burning sources was dominant, more than 80 % of particle number concentration remained after passing through the thermodenuder, suggesting that nearly all biomass burning particles had a nonvolatile core. These remaining particles consisted mostly of black carbon (60 % mass contribution) and organic aerosol (OA; 40 %). Organics that had not evaporated through the TD were mostly biomass burning OA (BBOA) and oxygenated OA (OOA) as determined from AMS source apportionment analysis. For periods during which traffic contribution was dominant 50-60 % of the particles had a nonvolatile core while the rest evaporated at 400 °C. The remaining particle mass consisted mostly of black carbon with an 80 % contribution, while OA was responsible for another 15-20 %. Organics were mostly hydrocarbon-like OA (HOA) and OOA. These results suggest that even at 400 °C some fraction of the OA does not evaporate from particles emitted from common combustion processes, such as biomass burning and car engines, indicating that a fraction of this type of OA

  19. Mass Size Distribution of Water Soluble Ions in Prague and Wiena in Summer

    OpenAIRE

    Schwarz, J; Vodička, P.; Zíková, N. (Naděžda); Hitzenberger, R.

    2012-01-01

    Aerosol mass size distribution is a key factor that influences aerosol behavior both on local (health effects, visibility) and global (global warming) level. The content of water soluble ions is the most important factor controlling hygroscopic behavior of aerosol particles. Hygroscopicity is a substantial parameter for particle deposition in lungs, particle – cloud interactions, aerosol optical effects etc. Therefore we studied size distribution of water soluble ions in two Central Europea...

  20. CCN activation and cloud processing in simplified sectional aerosol models with low size resolution

    OpenAIRE

    Korhonen, H.; Kerminen, V.-M.; Lehtinen, K. E. J.; Kulmala, M.

    2005-01-01

    International audience We investigate the influence of low size resolution, typical to sectional aerosol models in large scale applications, on cloud droplet activation and cloud processing of aerosol particles. A simplified cloud scheme with five approaches to determine the fraction of activated particles is compared with a detailed reference model under different atmospheric conditions. In general, activation approaches which assume a distribution profile within the critical model size s...

  1. CCN activation and cloud processing in sectional aerosol models with low size resolution

    OpenAIRE

    Korhonen, H.; V.-M. Kerminen; Lehtinen, K. E. J.; Kulmala, M.

    2005-01-01

    International audience We investigate the influence of low size resolution, typical to sectional aerosol models in large scale applications, on cloud droplet activation and cloud processing of aerosol particles. A simplified cloud model with five approaches to determine the fraction of activated particles is compared with a detailed reference model under different atmospheric conditions. In general, activation approaches which assume a distribution profile within the critical model size se...

  2. The effect of changes in humidity on the size of submicron aerosols

    International Nuclear Information System (INIS)

    The effect of humidity on inhaled aerosols in the respiratory tract is to cause an increase in particle size of up to several times if the aerosol particle is hygroscopic. The presence of ionizing radiation and air ions (for example, from uranium and radon/thoron) increases the tendency of water vapour to nucleate. The desposition of particles in the lung is enhanced by high charge density (>10 charges/particle). Radon has been reported to play an important role in the formation of sulphate and nitrate particles in the atmosphere. A detailed overview of the effect of humidity on aerosols is presented in the present work. Results of experimental measurements made on NaCl (hygroscopic) and kerosene combustion (hydrophobic) aerosols under ambient and humid conditions are reported. Initial aerosol conditions were 20 degrees C and 35% R.H. Final aerosol conditions were maintained at 37 degrees C and 100% R.H. in order to simulate the conditions inside the respiratory tract. An average growth factor of 1.9 ± 0.4 (standard deviation) was observed for the NaCl aerosol and 1.3 ± 0.2 (standard deviation) for the kerosene aerosol. For the activity size distribution, however, the NaCl aerosols were observed to grow by an average factor of only 1.2 ± 0.1 (standard deviation) whereas the kerosene aerosols grew by a factor of 1.3 ± 0.2 (standard deviation)

  3. Size segregated aerosol mass concentration measurements over the Arabian Sea during ICARB

    Indian Academy of Sciences (India)

    Vijayakumar S Nair; K Krishna Moorthy; S Suresh Babu; K Narasimhulu; L Siva Sankara Reddy; R Ramakrishna Reddy; K Rama Gopal; V Sreekanth; B L Madhavan; K Niranjan

    2008-07-01

    Mass concentration and mass size distribution of total (composite) aerosols near the surface are essential inputs needed in developing aerosol models for radiative forcing estimation as well as to infer the environment and air quality. Using extensive measurements onboard the oceanographic research vessel, Sagar Kanya, during its cruise SK223B in the second phase of the ocean segment of the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB), the spatial distribution of the mass concentration and mass size distribution of near-surface aerosols are examined for the first time over the entire Arabian Sea, going as far as 58°E and 22°N, within a span of 26 days. In general, the mass concentrations () were found to be low with the mean value for the entire Arabian Sea being 16.7 ± 7 g m−3; almost 1/2 of the values reported in some of the earlier campaigns. Coarse mode aerosols contributed, on an average, 58% to the total mass, even though at a few pockets accumulation mode contribution dominated. Spatially, significant variations were observed over central and northern Arabian Sea as well as close to the west coast of India. In central Arabian Sea, even though the was quite low, contribution of accumulation aerosols to the total mass concentration was greater than 50%. Effective radius, a parameter important in determining scattering properties of aerosol size distribution, varied between 0.07 and 0.4 m with a mean value of 0.2 m. Number size distributions, deduced from the mass size distributions, were approximated to inverse power-law form and the size indices () were estimated. It was found to vary in the range 3.9 to 4.2 with a mean value of 4.0 for the entire oceanic region. Extinction coefficients, estimated using the number-size distributions, were well-correlated with the accumulation mode mass concentration with a correlation coefficient of 0.82.

  4. Size Distribution of Natural Radioactive Aerosols in an Underground Building%某地下建筑内天然放射性气溶胶粒度分布研究

    Institute of Scientific and Technical Information of China (English)

    王海军; 王月兴; 杨翊方; 王震涛; 陈伟; 李珂娴

    2012-01-01

    天然放射性气溶胶粒度分布是评价氡暴露所致有效剂量的重要参数.本文采用撞击法对某地下建筑物室内天然放射性气溶胶的粒度分布进行试验研究,58个点位的4次测量表明:该建筑内天然放射性气溶胶粒度分布可采用单峰对数正态分布形式描述,活度中值空气动力学直径(AMAD)范围为0.087~0.427 μm,平均值为0.194 μm;AMAD主要分布在0.1~0.3 μm之间,约占全部测量结果的85%.%The size distribution of natural radioactive aerosols is a very important factor for evaluating the exposure dose contributed by radon. In order to measure the size distribution, a cascade impactor was employed for sampling in an underground building. The results of 4-time measurements at 58 places show that the sizes of natural radioactive aerosols are lognormal distribution, and the AMAD is between 0. 087 and 0. 427 μm with an average of 0. 194 μm. The AMADs ranging from 0. 1 to 0. 3 μm cover 85% of all data.

  5. Measurement of concentration and size distribution of aerosols in different radiation work places%放射性工作场所气溶胶浓度与粒径分布

    Institute of Scientific and Technical Information of China (English)

    拓飞; 徐翠华; 张庆; 李文红; 周强

    2011-01-01

    Objective:To explore the general characteristics of the concentration and size distribution of aerosols in several typical radiation work places. Methods:In different types of radiation work places, the number and mass concentration together with the number and mass particle size distribution of aerosols were measured by TSI 3321 APS. Results:The number median diameter distribution were averaged to be 0.7 μm for the whole surveyed places, while the mass median diameter of particle size distribution were around 1.0 μm, except for temporary storage pools of spent fuel rods at nuclear power plants. Both number and mass concentration in the room of processing unsealed radioactive source of C level were the highest. Conclusions:Concentration of aerosols varied with different work places and human activities significantly. The benchmark data established in this work may be useful when considering the dose contribution from inhaled radioactive particles.%目的:研究部分放射性工作场所内气溶胶的浓度和粒径分布特性。方法:在数类典型放射性工作场所,用TSI 3321APS进行气溶胶浓度和粒径分布的测量。结果:各调查场所的计数中位径均在0.7μm左右,除核电站乏燃料暂存池外,质量中位径均在1.0μm左右。放射性丙级操作室气溶胶的个数浓度和质量浓度最高。结论:气溶胶浓度与工作场所及人员活动关系密切,测量所建立的基线数据可为内照射剂量评价提供参考。

  6. Influence of aerosol vertical distribution on radiative budget and climate

    Science.gov (United States)

    Nabat, Pierre; Michou, Martine; Saint-Martin, David; Watson, Laura

    2016-04-01

    Aerosols interact with shortwave and longwave radiation with ensuing consequences on radiative budget and climate. Aerosols are represented in climate models either using an interactive aerosol scheme including prognostic aerosol variables, or using climatologies, such as monthly aerosol optical depth (AOD) fields. In the first case, aerosol vertical distribution can vary rapidly, at a daily or even hourly scale, following the aerosol evolution calculated by the interactive scheme. On the contrary, in the second case, a fixed aerosol vertical distribution is generally imposed by climatological profiles. The objective of this work is to study the impact of aerosol vertical distribution on aerosol radiative forcing, with ensuing effects on climate. Simulations have thus been carried out using CNRM-CM, which is a global climate model including an interactive aerosol scheme representing the five main aerosol species (desert dust, sea-salt, sulfate, black carbon and organic matter). Several multi-annual simulations covering the past recent years are compared, including either the prognostic aerosol variables, or monthly AOD fields with different aerosol vertical distributions. In the second case, AOD fields directly come from the first simulation, so that all simulations have the same integrated aerosol loads. The results show that modifying the aerosol vertical distribution has a significant impact on radiative budget, with consequences on global climate. These differences, highlighting the importance of aerosol vertical distribution in climate models, probably come from the modification of atmospheric circulation induced by changes in the heights of the different aerosols. Besides, nonlinear effects in the superposition of aerosol and clouds reinforce the impact of aerosol vertical distribution, since aerosol radiative forcing depends highly upon the presence of clouds, and upon the relative vertical position of aerosols and clouds.

  7. Polar organic marker compounds in atmospheric aerosols during the LBA-SMOCC 2002 biomass burning experiment in Rondônia, Brazil: sources and source processes, time series, diel variations and size distributions

    Directory of Open Access Journals (Sweden)

    M. Claeys

    2010-04-01

    PM mass in the size-segregated samples and was mainly present in the fine mode, except during the wet period where it peaked in the coarse mode. Isoprene SOA tracers showed an average concentration of 250 ng m−3 during the dry period versus 157 ng m−3 during the transition period and 52 ng m−3 during the wet period. Malic acid and the 2-methyltetrols exhibited a different size distribution pattern: while the 2-methyltetrols were mainly associated with the fine mode during all periods, malic acid was prevalent in the fine mode only during the dry and transition periods, while it was dominant in the coarse mode during the wet period, consistent with different formation processes. The sum of arabitol, mannitol, and erythritol in the PM2.5 fraction of the HVDS samples during the dry, transition, and wet periods was, on average, 54 ng m−3, 34 ng m−3, and 27 ng m−3, respectively, and revealed minor day/night variation. The mass size distributions of arabitol and mannitol during all periods showed similar patterns and an association with the coarse mode, consistent with their primary origin. The results show that even under the heavy smoke conditions of the dry period a natural background with contributions from bioaerosols and isoprene SOA can be revealed. The enhancement in isoprene SOA in the dry season is mainly attributed to an increased acidity of the aerosols and a decreased wet deposition.

  8. Evaluation of a global aerosol microphysics model against size-resolved particle statistics in the marine atmosphere

    OpenAIRE

    Spracklen, D. V.; Pringle, K. J.; K. S. Carslaw; G. W. Mann; P. Manktelow; Heintzenberg, J.

    2007-01-01

    A statistical synthesis of marine aerosol measurements from experiments in four different oceans is used to evaluate a global aerosol microphysics model (GLOMAP). We compare the model against observed size resolved particle concentrations, probability distributions, and the temporal persistence of different size particles. We attempt to explain the observed sub-micrometre size distributions in terms of sulfate and sea spray and quantify the possible contributions of anthropogenic sulfate and ...

  9. 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

    2010-07-01

    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 orders of magnitude less volatile than fresh laboratory-generated biogenic 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.

  10. Basamatikum - Combined Wide Size Range Aerosol Spectromeeter

    Czech Academy of Sciences Publication Activity Database

    Ondráček, Jakub; Mašková, Ludmila; Smolík, Jiří

    Praha: Czech Aerosol Society, 2013 - (Zíková, N.), s. 91-94 ISBN 978-80-86186-52-8. [Výroční konference České aerosolové společnosti /14./. Nový Smokovec, High Tatras (SK), 23.10.2013-25.10.2013] R&D Projects: GA MK DF11P01OVV020 Keywords : APS * indoor/outdoor * switching valve Subject RIV: CF - Physical ; Theoretical Chemistry

  11. Measurements of Atmospheric Aerosol Vertical Distributions above Svalbard, Norway using Unmanned Aerial Systems (UAS)

    Science.gov (United States)

    Bates, T. S.; Johnson, J. E.; Stalin, S.; Telg, H.; Murphy, D. M.; Burkhart, J. F.; Quinn, P.; Storvold, R.

    2015-12-01

    Atmospheric aerosol vertical distributions were measured above Svalbard, Norway in April 2015 to investigate the processes controlling aerosol concentrations and radiative effects. The aerosol payload was flown in a NOAA/PMEL MANTA Unmanned Aerial System (UAS) on 9 flights totaling 19 flight hours. Measurements were made of particle number concentration and aerosol light absorption at three wavelengths, similar to those conducted in April 2011 (Bates et al., Atmos. Meas. Tech., 6, 2115-2120, 2013). A filter sample was collected on each flight for analyses of trace elements. Additional measurements in the aerosol payload in 2015 included aerosol size distributions obtained using a Printed Optical Particle Spectrometer (POPS) and aerosol optical depth obtained using a four wavelength miniature Scanning Aerosol Sun Photometer (miniSASP). The data show most of the column aerosol mass and resulting optical depth in the boundary layer but frequent aerosol layers aloft with high particle number concentration (2000 cm-3) and enhanced aerosol light absorption (1 Mm-1). Transport of these aerosol layers was assessed using FLEXPART particle dispersion models. The data contribute to an assessment of sources of BC to the Arctic and potential climate impacts.

  12. On the accuracy of stratospheric aerosol extinction derived from in situ size distribution measurements and surface area density derived from remote SAGE II and HALOE extinction measurements

    Science.gov (United States)

    Kovilakam, Mahesh; Deshler, Terry

    2015-08-01

    In situ stratospheric aerosol measurements, from University of Wyoming optical particle counters (OPCs), are compared with Stratospheric Aerosol Gas Experiment (SAGE) II (versions 6.2 and 7.0) and Halogen Occultation Experiment (HALOE) satellite measurements to investigate differences between SAGE II/HALOE-measured extinction and derived surface area and OPC-derived extinction and surface area. Coincident OPC and SAGE II measurements are compared for a volcanic (1991-1996) and nonvolcanic (1997-2005) period. OPC calculated extinctions agree with SAGE II measurements, within instrumental uncertainty, during the volcanic period, but have been a factor of 2 low during the nonvolcanic period. Three systematic errors associated with the OPC measurements, anisokineticity, inlet particle evaporation, and counting efficiency, were investigated. An overestimation of the OPC counting efficiency is found to be the major source of systematic error. With this correction OPC calculated extinction increases by 15-30% (30-50%) for the volcanic (nonvolcanic) measurements. These changes significantly improve the comparison with SAGE II and HALOE extinctions in the nonvolcanic cases but slightly degrade the agreement in the volcanic period. These corrections have impacts on OPC-derived surface area density, exacerbating the poor agreement between OPC and SAGE II (version 6.2) surface areas. This disparity is reconciled with SAGE II version 7.0 surface areas. For both the volcanic and nonvolcanic cases these changes in OPC counting efficiency and in the operational SAGE II surface area algorithm leave the derived surface areas from both platforms in significantly better agreement and within the ± 40% precision of the OPC moment calculations.

  13. Stratospheric aerosol particle size information in Odin-OSIRIS limb scatter spectra

    Science.gov (United States)

    Rieger, L. A.; Bourassa, A. E.; Degenstein, D. A.

    2014-02-01

    The Optical Spectrograph and InfraRed Imaging System (OSIRIS) onboard the Odin satellite has now taken over a decade of limb scatter measurements that have been used to retrieve the version 5 stratospheric aerosol extinction product. This product is retrieved using a representative particle size distribution to calculate scattering cross sections and scattering phase functions for the forward model calculations. In this work the information content of OSIRIS measurements with respect to stratospheric aerosol is systematically examined for the purpose of retrieving particle size information along with the extinction coefficient. The benefit of using measurements at different wavelengths and scattering angles in the retrieval is studied, and it is found that incorporation of the 1530 nm radiance measurement is key for a robust retrieval of particle size information. It is also found that using OSIRIS measurements at the different solar geometries available on the Odin orbit simultaneously provides little additional benefit. Based on these results, an improved aerosol retrieval algorithm is developed that couples the retrieval of aerosol extinction and mode radius of a log-normal particle size distribution. Comparison of these results with coincident measurements from SAGE III shows agreement in retrieved extinction to within approximately 10% over the bulk of the aerosol layer, which is comparable to version 5. The retrieved particle size, when converted to Ångström coefficient, shows good qualitative agreement with SAGE II measurements made at somewhat shorter wavelengths.

  14. Mass size distribution of particles emitted by diesel engines and determination of the contribution of diesel particles to the atmospheric aerosol in Vienna by using a tracer suitable for activation analysis

    International Nuclear Information System (INIS)

    In Vienna a large fraction of light absorbing aerosols has been found. The traffic could be a source for the high absorption coefficients, since the time dependent absorption coefficients varise similar to the traffic densities. Diesel vehicles have high soot emissions, so they may contribute considerably to light absorption during the summer. The emission factors of the vehicles were estimated by measurements at different motor and driving conditions by the Constant-Volume-Sampling-Method. To determine the size distributions a 10-stage-low pressure impactor with a lower cut size of 0.015 μm aerodynamic particle diameter was used. In order to estimate the contribution of diesel vehicles to the total mass concentrations all diesel fuel sold in Vienna and its vincinity was marked with an organic Dysprosium compound. This rare earth tracer was emitted by vehicles together with the soot particles and collected at eleven stations in Vienna. The filter samples were extracted with diluted HNO3 and the extraction was analysed for Dy by neutron activation analysis. The mass size distributions of the particles and the soot emitted from diesel engines are only slightly influenced by motor and driving parameters. The total mass emissions showed considerable variations, but the mean emission factor obtained from the tests was 2.43 g per litre fuel; knowing also the concentration of the tracer in the fuel, the contribution of diesel particles to the mass of the suspended particulates could be estimated. During the measuring period the contribution was c. 25% to the total mass and c. 40% to the absorbing matter in the atmosphere. (Author)

  15. 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.

  16. Effect of aerosol particle size on bronchodilatation with nebulised terbutaline in asthmatic subjects.

    Science.gov (United States)

    Clay, M M; Pavia, D; Clarke, S W

    1986-05-01

    The bronchodilatation achieved by the beta 2 agonist terbutaline sulphate given as nebulised aerosol from different devices has been measured in seven patients with mild asthma (mean FEV1 76% predicted) over two hours after inhalation. The subjects were studied on four occasions. On three visits they received 2.5 mg terbutaline delivered from three different types of nebuliser, selected on the basis of the size distribution of the aerosols generated; and on a fourth (control) visit no aerosol was given. The size distributions of the aerosols expressed in terms of their mass median diameter (MMD) were: A: MMD 1.8 microns; B: 4.6 microns; C: 10.3 microns. The aerosols were given under controlled conditions of respiratory rate and tidal volume to minimise intertreatment variation. Bronchodilator response was assessed by changes in FEV1, forced vital capacity (FVC), peak expiratory flow (PEF), and maximal flow after expiration of 50% and 75% FVC (Vmax50, Vmax25) from baseline (before aerosol) and control run values. For each pulmonary function index all three aerosols gave significantly better improvement over baseline than was seen in the control (p less than 0.05) and had an equipotent effect on FEV1, FVC, and PEF. Aerosol A (MMD 1.8 microns) produced significantly greater improvements in Vmax50 and Vmax25 than did B or C (p less than 0.05). These results suggest that for beta 2 agonists small aerosols (MMD less than 2 microns) might be advantageous in the treatment of asthma. PMID:3750243

  17. Spatial distributions and seasonal cycles of aerosols in India and China seen in global climate-aerosol model

    Directory of Open Access Journals (Sweden)

    S. V. Henriksson

    2011-02-01

    Full Text Available A climate-aerosol model is employed to study spatial and temporal variability of aerosol properties over India and China for recent (year 2006 and future conditions (year 2020 under different emission pathways. We present results for aerosol mass concentration in different size classes and optical properties for the five different aerosol species treated by the model. Aerosol mass concentration and optical depth have significant contributions from both anthropogenic and natural aerosols. Different species have maxima in different regions, with the highest anthropogenic aerosol concentrations found in Kolkata and elsewhere in the Ganges basin in India and on the northern part of the east coast and in the Sichuan basin in China. In India natural aerosols have a maximum in the summer due to higher wind speeds and anthropogenic aerosols have a maximum in the winter due to less efficient wet removal. Surface concentrations are also higher in winter due to the additional reason of lower average boundary layer height. In China seasonal cycles are weaker with natural aerosols having a maximum in the spring and sulfate contribution to the aerosol optical depth (AOD being higher in the latter half of the year. MODIS AOD spatial distributions are reproduced well by the model, except for the Ganges valley with high absorption and for the Thar desert with high dust concentrations. Seasonal cycles compare well qualitatively with MODIS results. The larger AOD in China during the latter half of the year in the year 2006 simulation as compared to the MODIS data can be traced back to sulfate contribution with some contribution also from natural aerosols.

  18. Size distribution of detached drops

    Science.gov (United States)

    Baluev, V. V.; Stepanov, V. M.

    1989-10-01

    The law governing the size distribution of detached gas-liquid streams of drops has been determined analytically, and a comparison is carried out against experimental data existing in the literature. The derived theoretical relationships offer an excellent description of existing experimental results.

  19. Aerosol sampling: Comparison of two rotating impactors for field droplet sizing and volumetric measurements

    Science.gov (United States)

    This paper compares the collection characteristics of a new rotating impactor for ultra fine aerosols (FLB) with the industry standard (Hock). The volume and droplet size distribution collected by the rotating impactors were measured via spectroscopy and microscopy. The rotary impactors were co-lo...

  20. Aircraft studies of size-dependent aerosol sampling through inlets

    Science.gov (United States)

    Porter, J. N.; Clarke, A. D.; Ferry, G.; Pueschel, R. F.

    1992-01-01

    Representative measurement of aerosol from aircraft-aspirated systems requires special efforts in order to maintain near isokinetic sampling conditions, estimate aerosol losses in the sample system, and obtain a measurement of sufficient duration to be statistically significant for all sizes of interest. This last point is especially critical for aircraft measurements which typically require fast response times while sampling in clean remote regions. This paper presents size-resolved tests, intercomparisons, and analysis of aerosol inlet performance as determined by a custom laser optical particle counter. Measurements discussed here took place during the Global Backscatter Experiment (1988-1989) and the Central Pacific Atmospheric Chemistry Experiment (1988). System configurations are discussed including (1) nozzle design and performance, (2) system transmission efficiency, (3) nonadiabatic effects in the sample line and its effect on the sample-line relative humidity, and (4) the use and calibration of a virtual impactor.

  1. Observational characteristic of aerosol number concentration and size distribution at Shijiazhuang in spring season%石家庄春季大气气溶胶数浓度和谱的观测特征

    Institute of Scientific and Technical Information of China (English)

    翟晴飞; 金莲姬; 林振毅; 吴志会; 匡顺四

    2011-01-01

    利用美国MSP公司生产的宽范围粒径谱仪(WPS)于2010年5月在石家庄市气象局进行了近地面大气气溶胶数浓度的观测,并结合该市同期的气象资料,分析了该次观测所得的大气气溶胶粒子数浓度和谱的特征及其成因.结果表明,本次观测到的气溶胶以超细粒子(粒径<0.1μm)为主,各粒径范围内的颗粒物数浓度平均值很高.污染气体和颗粒物排放量高、风速较小以及东南风为主导风向所引起的输送作用是观测期间颗粒物污染严重的主要原因:受太阳辐射、温度、边界层高度和建筑施工的影响,晴天气溶胶粒子数浓度日变化明显,且不同粒径气溶胶粒子数浓度日变化差异显著,气溶胶粒子总数浓度和超细粒子数浓度均在7:00、12:00和21:00达到峰值,而粗粒子(粒径>0.1μm)数浓度峰值出现时间为7:00和23:00.%During May, 2010, number concentration of atmospheric aerosols near the ground at Shijiazhuang Meteorological Bureau, China were measured using WPS made by MSP Corporation in United States, combined with corresponding meteorological data, to study the characteristics of aerosol number concentration and size distribution in this observation and possible causes that lead to. The spectra of aerosol were mainly occupied by ultrafine particles(Dp<0.1μm) in this observation. The average particle number concentration was high in all size scales. High emission of pollution gases and particles, weak wind condition and the transport effect when the dominant wind direction was southeast were the primary possible causes of this result. Obvious diurnal variation of aerosol concentration was observed in sunny days, which was mainly controlled by solar radiation, heat condition, the height of the boundary layer and construction, and that between different diameters had significant differences. Both total and ultrafine particles number concentration reached daily peak value at 7:00, 12:00 and 21

  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

    2012-08-01

    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, OC and major ions in the city were 2–22 times higher than those on the mountaintop during the whole sampling period. Sulfate was the highest species in the nonevent time in Xi'an and Mt. Hua, followed by nitrate, OC and NH4+. In contrast, OC was the most abundant in the event at both sites, followed by sulfate, nitrate and Ca2+. Compared to those on the urban ground surface aerosols in the elevated troposphere over Mt. Hua contain more sulfate and less nitrate, because HNO3 is formed faster than H2SO4 and thus long-range transport of HNO3 is less significant than that of H2SO4. An increased water-soluble organic nitrogen (WSON was observed for the dust samples from Xi'an, indicating a significant deposition of anthropogenic WSON onto dust and/or an input of biogenic WSON from Gobi desert.

    As far as we know, it is for the first time to perform a simultaneous observation of aerosol chemistry between the ground surface and the free troposphere in inland East Asia. Our results showed that fine particles are more acidic on the mountaintop than on the urban ground surface in the nonevent, mainly due to continuous oxidation of SO2 to produce H2SO4 during the transport from lowland areas to the alpine atmosphere. However, we found the urban fine particles became more acidic in the event than in the nonevent, in contrast to the mountain atmosphere, where fine particles were less acidic when dust was present. The opposite changes in acidity of fine particles at both sites during the event are mostly caused by

  3. ON THE PROPORTIONALITY OF FINE MASS CONCENTRATION AND EXTINCTION COEFFICIENT FOR BIMODAL SIZE DISTRIBUTIONS

    Science.gov (United States)

    For a bimodal size distribution of ambient aerosol, an upper limit in particle size can be chosen for the fine aerosol fraction so that the extinction coefficient for light scattering and absorption is directly proportional to the fine mass concentration, with no dependence on th...

  4. Quantitative assessment of organosulfates in size-segregated rural fine aerosol

    Directory of Open Access Journals (Sweden)

    H. Lukács

    2008-04-01

    Full Text Available Organosulfates have recently come into the focus of organic aerosol research as potentially important components of water-soluble secondary organic aerosol (SOA which now dominate tropospheric fine aerosol. Their presence has been confirmed by the identification of sulfate esters of abundant biogenic carbonyl compounds in both smog chamber and continental aerosol. However, none of the studies have been able to determine the mass contribution of organosulfates to SOA.

    In this paper, as possibly the very first attempt to quantify organosulfates in ambient aerosol, we inferred the mass concentrations of organosulfates by concurrently determining mass concentrations of total sulfur, sulfate and methanesulfonate in rural fine aerosol using two highly sensitive analytical techniques. Although uncertainties were relatively large, we found that mass concentrations of organosulfates in water-soluble fine aerosol ranged from 0.02 μgS m−3 to 0.09 μgS m−3 yielding a mass contribution of 6–12% to bulk sulfur concentrations (or 6–14% to sulfate concentrations. The inferred size distribution of organosulfates suggested that they possibly form in heterogeneous reactions from semi-volatile carbonyl compounds with subsequent or concurrent condensation of gaseous sulfuric acid producing a refractory organic film on particle surfaces.

  5. Number size distributions and seasonality of submicron particles in Europe 2008-2009

    Science.gov (United States)

    Asmi, A.; Wiedensohler, A.; Laj, P.; Fjaeraa, A.-M.; Sellegri, K.; Birmili, W.; Weingartner, E.; Baltensperger, U.; Zdimal, V.; Zikova, N.; Putaud, J.-P.; Marinoni, A.; Tunved, P.; Hansson, H.-C.; Fiebig, M.; Kivekäs, N.; Lihavainen, H.; Asmi, E.; Ulevicius, V.; Aalto, P. P.; Swietlicki, E.; Kristensson, A.; Mihalopoulos, N.; Kalivitis, N.; Kalapov, I.; Kiss, G.; de Leeuw, G.; Henzing, B.; Harrison, R. M.; Beddows, D.; O'Dowd, C.; Jennings, S. G.; Flentje, H.; Weinhold, K.; Meinhardt, F.; Ries, L.; Kulmala, M.

    2011-06-01

    Two years of harmonized aerosol number size distribution data from 24 European field monitoring sites have been analysed. The results give a comprehensive overview of the European near surface aerosol particle number concentrations and number size distributions between 30 and 500 nm of dry particle diameter. Spatial and temporal distribution of aerosols in the particle sizes most important for climate applications are presented. We also analyse the annual, weekly and diurnal cycles of the aerosol number concentrations, provide log-normal fitting parameters for median number size distributions, and give guidance notes for data users. Emphasis is placed on the usability of results within the aerosol modelling community. We also show that the aerosol number concentrations of Aitken and accumulation mode particles (with 100 nm dry diameter as a cut-off between modes) are related, although there is significant variation in the ratios of the modal number concentrations. Different aerosol and station types are distinguished from this data and this methodology has potential for further categorization of stations aerosol number size distribution types. The European submicron aerosol was divided into characteristic types: Central European aerosol, characterized by single mode median size distributions, unimodal number concentration histograms and low variability in CCN-sized aerosol number concentrations; Nordic aerosol with low number concentrations, although showing pronounced seasonal variation of especially Aitken mode particles; Mountain sites (altitude over 1000 m a.s.l.) with a strong seasonal cycle in aerosol number concentrations, high variability, and very low median number concentrations. Southern and Western European regions had fewer stations, which decreases the regional coverage of these results. Aerosol number concentrations over the Britain and Ireland had very high variance and there are indications of mixed air masses from several source regions; the

  6. VERTICAL DISTRIBUTION OF ATMOSPHERIC AEROSOL CONCENTRATION AT XIANGHE

    Institute of Scientific and Technical Information of China (English)

    Li Xu; Guangyu Shi; Jun Zhou; Yasunobu Iwasaka

    2004-01-01

    This paper summarizes atmospheric aerosol concentrations of 5 stratospheric balloon soundings during the period from 1984 to 1994. Aerosol-rich layers in the troposphere were detected and the causes were analyzed. The main results are as follows: (1) the vertical distribution of the atmospheric aerosol is affected by atmospheric dynamic processes, humidity, etc.; (2) the tropospheric column concentrations of aerosol were 72.2×105, 20.2×105, 20.7×105 and 34.4×105 cm-2 and occupying 81%, 61% and 60% of the 0-to-30 km aerosol column, on Aug. 23, 1984, Aug. 22, 1993,Sept. 12, 1993 and Sept. 15, 1994, respectively; (3) the effect of volcano eruption was still evident in the aerosol profiles,28 and 27 months after the El Chichon and Pinatubo eruption; (4) the aerosol concentration in the troposphere did not decrease at all heights as atmospheric aerosol model.

  7. CCN activation and cloud processing in sectional aerosol models with low size resolution

    Directory of Open Access Journals (Sweden)

    H. Korhonen

    2005-01-01

    Full Text Available We investigate the influence of low size resolution, typical to sectional aerosol models in large scale applications, on cloud droplet activation and cloud processing of aerosol particles. A simplified cloud model with five approaches to determine the fraction of activated particles is compared with a detailed reference model under different atmospheric conditions. In general, activation approaches which assume a distribution profile within the critical model size sections predict the cloud droplet concentration most accurately under clean and moderately polluted conditions. In such cases, the deviation from the reference simulations is below 15% except for very low updraft velocities. In highly polluted cases, the concentration of cloud droplets is significantly overestimated due to the inability of the simplified model to account for the kinetic limitations of the droplet growth. Of the profiles examined, taking into account the local shape of the particle size distribution is the most accurate although in most cases the shape of the profile has little relevance. While the low resolution cloud model cannot reproduce the details of the out-of-the-cloud aerosol size distribution, it captures well the amount of sulphate produced in aqueous-phase reactions as well as the distribution of the sulphate between the cloud droplets. Overall, the simplified cloud model with low size resolution performs well for clean and moderately polluted regions that cover most of the Earth's surface and is therefore suitable for large scale models. It can, however, show uncertainties in areas with strong pollution from anthropogenic sources.

  8. Measurement of the electrostatic charge in airborne particles: II - particle charge distribution of different aerosols

    Directory of Open Access Journals (Sweden)

    M. V. Rodrigues

    2006-03-01

    Full Text Available This work gives sequence to the study on the measurement of the electrostatic charges in aerosols. The particle charge classifier developed for this purpose and presented in the previous paper (Marra and Coury, 2000 has been used here to measure the particle charge distribution of a number of different aerosols. The charges acquired by the particles were naturally derived from the aerosol generation procedure itself. Two types of aerosol generators were used: the vibrating orifice generator and turntable Venturi plate generator. In the vibrating orifice generator, mono-dispersed particles were generated by a solution of water/ethanol/methylene blue, while in the rotating plate generator, six different materials were utilized. The results showed no clear dependence between electric charge and particle diameter for the mono-dispersed aerosol. However, for the poly-dispersed aerosols, a linear dependence between particle size and charge could be noticed.

  9. Distribution of Aerosol During Diwali Festival in the Recent Decade over India

    Science.gov (United States)

    Gouda, K. C.; Bhat, N.; Goswami, P.

    2012-12-01

    Diwali is a very famous festival in India during which people play with crackers and fireworks. Due to burning of crackers and fireworks, the concentration of anthropogenic aerosol increases in the atmosphere. In the present work the temporal and spatial variation of atmospheric aerosol parameters like Aerosol Optical Thickness (AOT), Aerosol Depth (AOD), TWC, Aerosol Particle size etc. are analyzed using the high resolution satellite data from different sources. 10 year Climatology of the Aerosol over India is generated using the data before, after and during Diwali festival time for the period of 2002 to 2011. The three climatologies show different distribution of the aerosol parameters through out the country. The northern and eastern part shows more rich in the aerosol during the festival. To understand the temporal variability, analysis of aerosol properties are being carried out one week before the festival day and one week after the festival day and compared with the day of festival for all the years. It is observed that the AOD increases from the preceding days of the festival since people start playing with crackers and fireworks about two days prior to the main Diwali day especially in North India. It is also observed from the present study that during the Diwali month the aerosol parameters are maximum in Northern part of India which supports the practice of higher incidences of bio-mass burning and residues of waste agricultural crop's fire activities. Ten year (2002-2011) average distribution of MODIS derived Aerosol Optical Thickness (AOT) during Diwali over India is presented in figure 1. A complete evaluation of distribution of AOT, AOD, TWC, Rainfall, suspended particulate Material etc. along with statistical analysis are also presented in this work. Figure 1: Ten year (2002-2011) average distribution of MODIS derived Aerosol Optical Thickness (AOT) during Diwali over India

  10. Chemical composition and size distribution of summertime PM2.5 at a high altitude remote location in the northeast of the Qinghai–Xizang (Tibet) Plateau: insights into aerosol sources and processing in free troposphere

    OpenAIRE

    J. Z. Xu; Q. Zhang; Wang, Z. B.; Yu, G. M.; Ge, X. L.; Qin, X

    2015-01-01

    Aerosol filter samples were collected at a high-elevation mountain observatory (4180 m a.s.l.) in the northeastern part of the Qinghai–Xizang (Tibet) Plateau (QXP) during summer 2012 using a low-volume sampler and a micro-orifice uniform deposit impactor (MOUDI). These samples were analyzed for water-soluble inorganic ions (WSIs), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and total organic nitrogen (TON) to elucidate the size-resolved chem...

  11. Intercomparison of 15 aerodynamic particle size spectrometers (APS 3321: uncertainties in particle sizing and number size distribution

    Directory of Open Access Journals (Sweden)

    S. Pfeifer

    2015-11-01

    Full Text Available Aerodynamic particle size spectrometers are a well-established method to measure number size distributions of coarse mode particles in the atmosphere. Quality assurance is essential for atmospheric observational aerosol networks to obtain comparable results with known uncertainties. In a laboratory study within the framework of ACTRIS (Aerosols, Clouds, and Trace gases Research Infrastructure Network, 15 aerodynamic particle size spectrometers (APS model 3321, TSI Inc., St. Paul, MN, USA were compared with a focus on flow rates accuracy, particle sizing, and unit-to-unit variability of the particle number size distribution. Flow rate deviations were relatively small (within a few percent, while the sizing accuracy was found to be within 10 % compared to polystyrene latex (PSL reference particles. The unit-to-unit variability in terms of the particle number size distribution during this study was within 10–20 % for particles in the range of 0.9 up to 3 μm, which is acceptable for atmospheric measurements. For particles smaller than that, the variability increased up to 60 %, probably caused by differences in the counting efficiencies of individual units. Number size distribution data for particles smaller than 0.9 μm in aerodynamic diameter should be only used with caution. For particles larger than 3 μm, the unit-to-unit variability increased as well. A possible reason is an insufficient sizing accuracy in combination with a steeply sloping particle number size distribution and the increasing uncertainty due to decreasing counting. This uncertainty of the particle number size distribution has especially to be considered if higher moments of the size distribution such as the particle volume or mass are calculated, which require the conversion of the aerodynamic diameter measured to a volume equivalent diameter. In order to perform a quantitative quality assurance, a traceable reference method for the particle number concentration in the size

  12. Intercomparison of 15 aerodynamic particle size spectrometers (APS 3321): uncertainties in particle sizing and number size distribution

    Science.gov (United States)

    Pfeifer, Sascha; Müller, Thomas; Weinhold, Kay; Zikova, Nadezda; Martins dos Santos, Sebastiao; Marinoni, Angela; Bischof, Oliver F.; Kykal, Carsten; Ries, Ludwig; Meinhardt, Frank; Aalto, Pasi; Mihalopoulos, Nikolaos; Wiedensohler, Alfred

    2016-04-01

    Aerodynamic particle size spectrometers are a well-established method to measure number size distributions of coarse mode particles in the atmosphere. Quality assurance is essential for atmospheric observational aerosol networks to obtain comparable results with known uncertainties. In a laboratory study within the framework of ACTRIS (Aerosols, Clouds, and Trace gases Research Infrastructure Network), 15 aerodynamic particle size spectrometers (APS model 3321, TSI Inc., St. Paul, MN, USA) were compared with a focus on flow rates, particle sizing, and the unit-to-unit variability of the particle number size distribution. Flow rate deviations were relatively small (within a few percent), while the sizing accuracy was found to be within 10 % compared to polystyrene latex (PSL) reference particles. The unit-to-unit variability in terms of the particle number size distribution during this study was within 10 % to 20 % for particles in the range of 0.9 up to 3 µm, which is acceptable for atmospheric measurements. For particles smaller than that, the variability increased up to 60 %, probably caused by differences in the counting efficiencies of individual units. Number size distribution data for particles smaller than 0.9 µm in aerodynamic diameter should only be used with caution. For particles larger than 3 µm, the unit-to-unit variability increased as well. A possible reason is an insufficient sizing accuracy in combination with a steeply sloping particle number size distribution and the increasing uncertainty due to decreasing counting. Particularly this uncertainty of the particle number size distribution must be considered if higher moments of the size distribution such as the particle volume or mass are calculated, which require the conversion of the aerodynamic diameter measured to a volume equivalent diameter. In order to perform a quantitative quality assurance, a traceable reference method for the particle number concentration in the size range 0.5-3 µm

  13. 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.

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

    Science.gov (United States)

    Lee, B. H.; Kostenidou, E.; Hildebrandt, L.; Riipinen, I.; Engelhart, G. J.; Mohr, C.; Decarlo, P. F.; Mihalopoulos, N.; Prevot, A. S. H.; Baltensperger, U.; Pandis, S. N.

    2010-12-01

    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.

  15. Relevance of aerosol size spectrum analysis as support to qualitative source apportionment studies

    International Nuclear Information System (INIS)

    This work presents a diagnostic methodology in support to source apportionment studies to identify remote and local pollution sources. It is based on the temporal analysis of both PM size distributions and PM size fraction correlation along with natural radioactivity measurements as index of Planetary Boundary Layer dynamic. A correlation drop is indicative of changing aerosol sources. When this observation is coupled with decreasing level of natural radioactivity and increasing aerosol concentration, be it coarse or fine, it is indicative of the inflow of remote polluted air masses. The methodology defines in which size range operates the contribution of remote pollution sources. It was applied to two PM10 pollution episodes: the first involved the advection of coarse PM, the second entailed the inflow of two air masses, one transporting coarse dust and the other fine PM. Dust models and backward trajectories analysis confirmed such results, indicating the air mass provenience. - Highlights: ► Tool as a qualitative support to source apportionment studies. ► Time and size resolved aerosol and natural radioactivity measurements. ► Methodology gives immediate information on PM presence from local/remote sources. ► Long range transport episodes are demonstrated without any chemical analysis. ► Dust models and backward-trajectory analysis used for confirming the results found. - Long range transport episodes are clearly demonstrated by time and size resolved aerosol and natural radioactivity measurements without any chemical analysis.

  16. A global off-line model of size-resolved aerosol microphysics: I. Model development and prediction of aerosol properties

    Directory of Open Access Journals (Sweden)

    D. V. Spracklen

    2005-01-01

    Full Text Available A GLObal Model of Aerosol Processes (GLOMAP has been developed as an extension to the TOMCAT 3-D Eulerian off-line chemical transport model. GLOMAP simulates the evolution of the global aerosol size distribution using a sectional two-moment scheme and includes the processes of aerosol nucleation, condensation, growth, coagulation, wet and dry deposition and cloud processing. We describe the results of a global simulation of sulfuric acid and sea spray aerosol. The model captures features of the aerosol size distribution that are well established from observations in the marine boundary layer and free troposphere. Modelled condensation nuclei (CN>3nm vary between about 250–500 cm-3 in remote marine boundary layer regions and are generally in good agreement with observations. Modelled continental CN concentrations are lower than observed, which may be due to lack of some primary aerosol sources or the neglect of nucleation mechanisms other than binary homogeneous nucleation of sulfuric acid-water particles. Remote marine CN concentrations increase to around 2000–10 000 cm (at standard temperature and pressure in the upper troposphere, which agrees with typical observed vertical profiles. Cloud condensation nuclei (CCN at 0.2% supersaturation vary between about 1000 cm-3 in polluted regions and between 10 and 500 cm-3 in the remote marine boundary layer. New particle formation through sulfuric acid-water binary nucleation occurs predominantly in the upper troposphere, but the model results show that these particles contribute greatly to aerosol concentrations in the marine boundary layer. For this sulfur-sea salt system it is estimated that sea spray emissions account for only ~10% of CCN in the tropical marine boundary layer, but between 20 and 75% in the mid-latitude Southern Ocean. In a run with only natural sulfate and sea salt emissions the global mean surface CN concentration is more than 60% of that from a run with 1985 anthropogenic

  17. Size Dependence of Chemical Reactions in Nanoscale Aerosol Particles

    Czech Academy of Sciences Publication Activity Database

    Levdansky, V.V.; Smolík, Jiří; Moravec, Pavel

    Helsinki : -, 2010, P2L1. ISBN N. [International Aerosol Conference IAC 2010. Helsinki (FI), 29.08.2010-03.09.2010] R&D Projects: GA ČR GA104/07/1093; GA ČR GA101/09/1633; GA AV ČR(CZ) IAA400720804 Institutional research plan: CEZ:AV0Z40720504 Keywords : size effect * nanoparticles * chemical reactions Subject RIV: CF - Physical ; Theoretical Chemistry www.iac2010.fi

  18. Influence of Size Effect on Evaporation of Aerosol Nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Levdansky, V.V.; Smolík, Jiří; Ždímal, Vladimír

    Praha : Czech Aerosol Society , 2013 - (Zíková, N.), s. 23-24 ISBN 978-80-86186-52-8. [Výroční konference České aerosolové společnosti /14./. Nový Smokovec, High Tatras (SK), 23.10.2013-25.10.2013] R&D Projects: GA AV ČR IAA200760905 Institutional support: RVO:67985858 Keywords : nanoparticles * size effect * evaporation Subject RIV: CF - Physical ; Theoretical Chemistry

  19. An overview of differential mobility analyzers for size classification of nanometer-sized aerosol particles

    Directory of Open Access Journals (Sweden)

    Nakorn Tippayawong

    2008-03-01

    Full Text Available Size classification of nanoparticles is an important process in the electrical mobility particle size analyzer. The differential mobility analyzer (DMA is one of the most commonly used devices for classifying and measuring nanometersized aerosol particles between 1 nm to 1 μm in diameter, based on their electrical mobility. The DMA can be described as an assembly of two concentrically cylindrical electrodes with an air gap between the walls. In the DMA, air and aerosol flows enter from one end, pass through the annulus and exit the other end. An electric field is applied between the inner and outer electrodes. Particles having a specific mobility exit with the monodisperse air flow through a small slit located at the bottom of the inner electrode. These particles are transferred to a particle counter to determine the particle number concentration. In the past several decades, there have been numerous extensive studies and developments on the DMA. Nonetheless, they are different in terms of specific applications, construction, particle size range, as well as time response and resolution. The purpose of this article is to provide an overview of the state-of-the-art existing cylindrical DMAs for aerosol particle size classification as well as for the generation of monodisperse aerosol in nanometer size range. A description of the operating principles, detailed physical characteristics of these DMAs, including the single-channel and multi-channel DMAs, as well as some examples of applications to nanotechnology are given.

  20. Surface Chemistry at Size-Selected Nano-Aerosol Particles

    Science.gov (United States)

    Roberts, Jeffrey

    2005-03-01

    A method has been developed to conduct surface chemistry and extract surface kinetic rates from size-selected aerosol nanoparticles. The measurements encompass broad ranges of particle size, phase, and composition. Results will be presented on the uptake of water by aerosolized soot nanoparticles of radius between 10 and 40 nm. Water uptake was monitored by tandem differential mobility analysis (T-DMA), which is capable of measuring changes in particle diameter as little as 0.2 nm. Soot particles were produced in an ethene diffusion flame and extracted into an atmospheric pressure aerosol flow tube reactor. The particles were subjected to various thermal and oxidative treatments, and the effects of these treatments on the ability of soot to adsorb monolayer quantities of water was determined. The results are important because soot nucleates atmospheric cloud particles. More generally, the results represent one of the first kinetic and mechanistic studies of gas-phase nanoparticle reactivity. Co-author: Henry Ajo, University of Minnesota

  1. Size-resolved trace metal characterization of aerosols emitted by four important source types in Switzerland

    Science.gov (United States)

    Buerki, Peter R.; Gaelli, Brigitte C.; Nyffeler, Urs P.

    In central Switzerland five types of emission sources are mainly responsible for airborne trace metals: traffic, industrial plants burning heavy oil, resuspension of soil particles, residential heatings and refuse incineration plants. The particulate emissions of each of these source types except refuse incineration were sampled using Berner impactors and the mass and elemental size distributions of Cd, Cu, Mn, Pb, Zn, As and Na determined. Cd, Na and Zn are not characteristic for any of these source types. As and Cu, occurring in the fine particle fractions are characteristic for heavy oil combustion, Mn for soil dust and sometimes for heavy and fuel oil combustion and Pb for traffic aerosols. The mass size distributions of aerosols originating from erosion and abrasion processes show a maximum mass fraction in the coarse particle range larger than about 1 μm aerodynamic equivalent diameters (A.E.D.). Aerosols originating from combustion processes show a second maximum mass fraction in the fine particle range below about 0.5μm A.E.D. Scanning electron microscopy combined with an EDS analyzer was used for the morphological characterization of emission and ambient aerosols.

  2. Effect of ethanol on droplet size, efficiency of delivery, and clearance characteristics of technetium-99m DTPA aerosol

    International Nuclear Information System (INIS)

    With recent technical advances in aerosol technology, the study of regional ventilation using [/sup 99m/Tc]DTPA aerosol has become increasingly popular. Using a cascade impactor, the authors have assessed droplet size distribution from a newly designed nebulizer. Delivery efficiency of [/sup 99m/Tc]DTPA aerosol to normal subjects was improved 70% with a 10% concentration of ethanol in the nebulizer. Using filter paper fixed to the delivery end of the aerosol device, and varying ethanol concentrations from 0-10%, an 87% increase of deposited radioactivity is measured. The addition of ethanol did not alter clearance characteristics of [/sup 99m/Tc]DTPA from the lung nor did it affect droplet size distribution

  3. AEROSOL MEASUREMENTS IN THE SUBMICRON SIZE RANGE, STUDIES WITH AN AEROSOL CENTRIFUGE, A NEW DIFFUSION BATTERY, A LOW PRESSURE IMPACTOR AND AN ADVANCED CONDENSATION NUCLEI COUNTER

    Science.gov (United States)

    The report summarizes the investigations of four aerosol classifiers which cover finite, but overlapping ranges of the aerosol particle size spectrum. The first part is concerned with a cylindrical aerosol centrifuge, which measures aerodynamic equivalent diameters precisely. Thi...

  4. Variation of particle number concentration and size distributions at the urban environment in Vilnius (Lithuania)

    Science.gov (United States)

    Ulevicius, Vidmantas; Byčenkienë, Steigvilë; Plauškaitë, Kristina; Dudoitis, Vadimas

    2013-05-01

    This study presents results of research on urban aerosol particles with a focus on the particle size distribution and the aerosol particle number concentration (PNC). The real time measurements of the aerosol PNC in the size range of 9-840 nm were performed at the urban background site using a Condensed Particle Counter and Scanning Mobility Particle Sizer (SMPS). Strong diurnal patterns in aerosol PNC were evident as a direct effect of three sources of the aerosol particles (nucleation, traffic, and residential heating appliances). The traffic exhaust emissions were a major contributor of the pollution observed at the roadside site that was dominated by the nucleation mode particles, while particles formed due to the residential heating appliances and secondary formation processes contributed to the accumulation mode particles and could impact the variation of PNC and its size distribution during the same day.

  5. LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles – Part 2: First results from balloon and unmanned aerial vehicle flights

    Directory of Open Access Journals (Sweden)

    J.-B. Renard

    2015-09-01

    Full Text Available In the companion paper (Renard et al., 2015, we have described and evaluated a new versatile optical particle counter/sizer named LOAC (Light Optical Aerosol Counter based on scattering measurements at angles of 12 and 60° that allows some topology identification of particles (droplets, carbonaceous, salts, and mineral dust in addition to size segregated counting in a large diameter range from 0.2 up to possibly more than 100 μm depending on sampling conditions. Its capabilities overpass those of preceding optical particle counters (OPCs allowing the characterization of all kind of aerosols from submicronic-sized absorbing carbonaceous particles in polluted air to very coarse particles (> 10–20 μm in diameter in desert dust plumes or fog and clouds. LOAC's light and compact design allows measurements under all kinds of balloons, on-board unmanned aerial vehicles (UAV and at ground level. We illustrate here the first LOAC airborne results obtained from an unmanned aerial vehicle (UAV and a variety of scientific balloons. The UAV was deployed in a peri-urban environment near Bordeaux in France. Balloon operations include (i tethered balloons deployed in urban environments in Vienna (Austria and Paris (France, (ii pressurized balloons drifting in the lower troposphere over the western Mediterranean (during the Chemistry-Aerosol Mediterranean Experiment – ChArMEx campaigns, (iii meteorological sounding balloons launched in the western Mediterranean region (ChArMEx and from Aire-sur-l'Adour in south-western France (VOLTAIRE-LOAC campaign. More focus is put on measurements performed in the Mediterranean during (ChArMEx and especially during African dust transport events to illustrate the original capability of balloon-borne LOAC to monitor in situ coarse mineral dust particles. In particular, LOAC has detected unexpected large particles in desert sand plumes.

  6. LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles - Part 2: First results from balloon and unmanned aerial vehicle flights

    Science.gov (United States)

    Renard, Jean-Baptiste; Dulac, François; Berthet, Gwenaël; Lurton, Thibaut; Vignelles, Damien; Jégou, Fabrice; Tonnelier, Thierry; Jeannot, Matthieu; Couté, Benoit; Akiki, Rony; Verdier, Nicolas; Mallet, Marc; Gensdarmes, François; Charpentier, Patrick; Mesmin, Samuel; Duverger, Vincent; Dupont, Jean-Charles; Elias, Thierry; Crenn, Vincent; Sciare, Jean; Zieger, Paul; Salter, Matthew; Roberts, Tjarda; Giacomoni, Jérôme; Gobbi, Matthieu; Hamonou, Eric; Olafsson, Haraldur; Dagsson-Waldhauserova, Pavla; Camy-Peyret, Claude; Mazel, Christophe; Décamps, Thierry; Piringer, Martin; Surcin, Jérémy; Daugeron, Daniel

    2016-08-01

    In the companion (Part I) paper, we have described and evaluated a new versatile optical particle counter/sizer named LOAC (Light Optical Aerosol Counter), based on scattering measurements at angles of 12 and 60°. That allows for some typology identification of particles (droplets, carbonaceous, salts, and mineral dust) in addition to size-segregated counting in a large diameter range from 0.2 µm up to possibly more than 100 µm depending on sampling conditions (Renard et al., 2016). Its capabilities overpass those of preceding optical particle counters (OPCs) allowing the characterization of all kind of aerosols from submicronic-sized absorbing carbonaceous particles in polluted air to very coarse particles (> 10-20 µm in diameter) in desert dust plumes or fog and clouds. LOAC's light and compact design allows measurements under all kinds of balloons, on-board unmanned aerial vehicles (UAVs) and at ground level. We illustrate here the first LOAC airborne results obtained from a UAV and a variety of scientific balloons. The UAV was deployed in a peri-urban environment near Bordeaux in France. Balloon operations include (i) tethered balloons deployed in urban environments in Vienna (Austria) and Paris (France), (ii) pressurized balloons drifting in the lower troposphere over the western Mediterranean (during the Chemistry-Aerosol Mediterranean Experiment - ChArMEx campaigns), (iii) meteorological sounding balloons launched in the western Mediterranean region (ChArMEx) and from Aire-sur-l'Adour in south-western France (VOLTAIRE-LOAC campaign). More focus is put on measurements performed in the Mediterranean during (ChArMEx) and especially during African dust transport events to illustrate the original capability of balloon-borne LOAC to monitor in situ coarse mineral dust particles. In particular, LOAC has detected unexpected large particles in desert sand plumes.

  7. LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles - Part 2: First results from balloon and unmanned aerial vehicle flights

    Science.gov (United States)

    Renard, J.-B.; Dulac, F.; Berthet, G.; Lurton, T.; Vignelles, D.; Jégou, F.; Tonnelier, T.; Thaury, C.; Jeannot, M.; Couté, B.; Akiki, R.; Verdier, N.; Mallet, M.; Gensdarmes, F.; Charpentier, P.; Mesmin, S.; Duverger, V.; Dupont, J. C.; Elias, T.; Crenn, V.; Sciare, J.; Giacomoni, J.; Gobbi, M.; Hamonou, E.; Olafsson, H.; Dagsson-Waldhauserova, P.; Camy-Peyret, C.; Mazel, C.; Décamps, T.; Piringer, M.; Surcin, J.; Daugeron, D.

    2015-09-01

    In the companion paper (Renard et al., 2015), we have described and evaluated a new versatile optical particle counter/sizer named LOAC (Light Optical Aerosol Counter) based on scattering measurements at angles of 12 and 60° that allows some topology identification of particles (droplets, carbonaceous, salts, and mineral dust) in addition to size segregated counting in a large diameter range from 0.2 up to possibly more than 100 μm depending on sampling conditions. Its capabilities overpass those of preceding optical particle counters (OPCs) allowing the characterization of all kind of aerosols from submicronic-sized absorbing carbonaceous particles in polluted air to very coarse particles (> 10-20 μm in diameter) in desert dust plumes or fog and clouds. LOAC's light and compact design allows measurements under all kinds of balloons, on-board unmanned aerial vehicles (UAV) and at ground level. We illustrate here the first LOAC airborne results obtained from an unmanned aerial vehicle (UAV) and a variety of scientific balloons. The UAV was deployed in a peri-urban environment near Bordeaux in France. Balloon operations include (i) tethered balloons deployed in urban environments in Vienna (Austria) and Paris (France), (ii) pressurized balloons drifting in the lower troposphere over the western Mediterranean (during the Chemistry-Aerosol Mediterranean Experiment - ChArMEx campaigns), (iii) meteorological sounding balloons launched in the western Mediterranean region (ChArMEx) and from Aire-sur-l'Adour in south-western France (VOLTAIRE-LOAC campaign). More focus is put on measurements performed in the Mediterranean during (ChArMEx) and especially during African dust transport events to illustrate the original capability of balloon-borne LOAC to monitor in situ coarse mineral dust particles. In particular, LOAC has detected unexpected large particles in desert sand plumes.

  8. Size dependence of phase transitions in aerosol nanoparticles

    Science.gov (United States)

    Cheng, Yafang; Su, Hang; Koop, Thomas; Mikhailov, Eugene; Pöschl, Ulrich

    2015-01-01

    Phase transitions of nanoparticles are of fundamental importance in atmospheric sciences, but current understanding is insufficient to explain observations at the nano-scale. In particular, discrepancies exist between observations and model predictions of deliquescence and efflorescence transitions and the hygroscopic growth of salt nanoparticles. Here we show that these discrepancies can be resolved by consideration of particle size effects with consistent thermodynamic data. We present a new method for the determination of water and solute activities and interfacial energies in highly supersaturated aqueous solution droplets (Differential Köhler Analysis). Our analysis reveals that particle size can strongly alter the characteristic concentration of phase separation in mixed systems, resembling the influence of temperature. Owing to similar effects, atmospheric secondary organic aerosol particles at room temperature are expected to be always liquid at diameters below ~20 nm. We thus propose and demonstrate that particle size should be included as an additional dimension in the equilibrium phase diagram of aerosol nanoparticles. PMID:25586967

  9. Dust Particle Size Distribution Inversion Based on the Multi Population Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Jiandong Mao and Juan Li

    2014-01-01

    Full Text Available The aerosol number size distribution is the main parameter for characterizing aerosol optical properties and physical properties, it has a major influence on radiation forcing. With regard to some disadvantages in the traditional methods, a method based on the multi population genetic algorithm (MPGA is proposed and employed to retrieve the aerosol size distribution of dust particles. The MPGA principles and design are presented in detail. The MPGA has better performance compared with conventional methods. In order to verify the feasibility of the inversion method, the measured aerosol optical thickness (AOT data of dust particles taken by a sun photometer are used and a series of comparisons between the simple genetic algorithm (SGA and MPGA are carried out. The results show that the MPGA presents better properties when compared with the SGA with smaller inversion errors, smaller population size and fewer generation numbers to retrieve the aerosol size distribution. The MPGA inversion method is analyzed using the background day, dust storm event and seasonal size distribution. The method proposed in this study has important applications and reference value for aerosol particle size distribution inversion.

  10. Aged Boreal Biomass Burning Size Distributions from Bortas 2011

    Science.gov (United States)

    Pierce, J. R.; Sakamoto, K.; Allan, J. D.; Coe, H.; Taylor, J.; Duck, T.

    2014-12-01

    Biomass-burning aerosols contribute to aerosol radiative forcing on the climate system. The magnitude of this effect is partially determined by aerosol size distributions, which are strong functions of source fire characteristics (e.g. fuel type, MCE) and in-plume microphysical processing. The uncertainties in biomass-burning emission number size-distributions in climate model inventories lead to uncertainties in the CCN concentrations and forcing estimates derived from these models. The BORTAS-B measurement campaign was designed to sample boreal biomass-burning outflow over Eastern Canada in the summer of 2011. Using these BORTAS-B data, we implement plume criteria to isolate the characteristic size-distribution of aged biomass-burning emissions (aged ~ 1.5 - 2 days) from boreal wildfires in Northwestern Ontario. The composite median size-distribution yields a single dominant accumulation mode with Dpm = 232 nm, σ = 1.7, which are comparable to literature values of other aged plumes of a similar type. The organic aerosol enhancement ratios (ΔOA/ΔCO) along the path of Flight b622 show values of 0.08-0.18 μg m-3 ppbv-1 with no significant trend with distance from the source. This lack of enhancement ratio increase/decrease with distance suggests no detectable net OA production/evaporation within the aged plume over the sampling period. A Lagrangian microphysical model was used to determine an estimate of the freshly emitted size distribution and flux corresponding to the BORTAS-B aged size-distributions. The model was restricted to coagulation and dilution processes only based on the insignificant net OA production/evaporation derived from the ΔOA/ΔCO enhancement ratios. Depending on the, we estimate that the fresh-plume median diameter was in the range of 59-94 nm with modal widths in the range of 1.7-2.8. Thus, the size of the freshly emitted particles is somewhat unconstrained due to the uncertainties in the plume dilution rates.

  11. Method for measuring the size distribution of airborne rhinovirus

    International Nuclear Information System (INIS)

    About 50% of viral-induced respiratory illnesses are caused by the human rhinovirus (HRV). Measurements of the concentrations and sizes of bioaerosols are critical for research on building characteristics, aerosol transport, and mitigation measures. We developed a quantitative reverse transcription-coupled polymerase chain reaction (RT-PCR) assay for HRV and verified that this assay detects HRV in nasal lavage samples. A quantitation standard was used to determine a detection limit of 5 fg of HRV RNA with a linear range over 1000-fold. To measure the size distribution of HRV aerosols, volunteers with a head cold spent two hours in a ventilated research chamber. Airborne particles from the chamber were collected using an Andersen Six-Stage Cascade Impactor. Each stage of the impactor was analyzed by quantitative RT-PCR for HRV. For the first two volunteers with confirmed HRV infection, but with mild symptoms, we were unable to detect HRV on any stage of the impactor

  12. Method for measuring the size distribution of airborne rhinovirus

    Energy Technology Data Exchange (ETDEWEB)

    Russell, M.L.; Goth-Goldstein, R.; Apte, M.G.; Fisk, W.J.

    2002-01-01

    About 50% of viral-induced respiratory illnesses are caused by the human rhinovirus (HRV). Measurements of the concentrations and sizes of bioaerosols are critical for research on building characteristics, aerosol transport, and mitigation measures. We developed a quantitative reverse transcription-coupled polymerase chain reaction (RT-PCR) assay for HRV and verified that this assay detects HRV in nasal lavage samples. A quantitation standard was used to determine a detection limit of 5 fg of HRV RNA with a linear range over 1000-fold. To measure the size distribution of HRV aerosols, volunteers with a head cold spent two hours in a ventilated research chamber. Airborne particles from the chamber were collected using an Andersen Six-Stage Cascade Impactor. Each stage of the impactor was analyzed by quantitative RT-PCR for HRV. For the first two volunteers with confirmed HRV infection, but with mild symptoms, we were unable to detect HRV on any stage of the impactor.

  13. Confronting AeroCom models with particle size distribution data from surface in situ stations

    Science.gov (United States)

    Platt, Stephen; Fiebig, Markus; Mann, Graham; Schulz, Michael

    2016-04-01

    The size distribution is the most important property for describing any interaction of an aerosol particle population with its surroundings. In first order, it determines both, the aerosol optical properties quantifying the direct aerosol climate effect, and the fraction of aerosol particles acting as cloud condensation nuclei quantifying the indirect aerosol climate effect. Aerosol schemes of modern climate models resolve the aerosol particle size distribution (APSD) explicitly. In improving the skill of climate models, it is therefore highly useful to confront these models with precision APSD data observed at surface stations. Corresponding previous work focussed on comparing size integrated, seasonal particle concentrations at selected sites with ensemble model averages to assess overall model skill. Building on this work, this project intends to refine the approach by comparing median particle size and integral concentration of fitted modal size distributions. It will also look at skill differences between models in order to find reasons for matches and discrepancies. The presentation will outline the project, and will elaborate on input requested from modelling groups to participate in the exercise.

  14. Variations in Tropospheric Submicron Particle Size Distributions Across the European Continent 2008–2009

    Czech Academy of Sciences Publication Activity Database

    Beddows, D.C.S.; Dall’Osto, M.; Harrison, R.M.; Kulmala, M.; Asmi, A.; Wiedensohler, A.; Laj, P.; Fjaeraa, A.M.; Sellegri, K.; Birmili, W.; Bukowiecki, N.; Weingartner, E.; Baltensperger, U.; Ždímal, Vladimír; Zíková, Naděžda; Putaud, J.-P.; Marinoni, A.; Tunved, P.; Hansson, H.-C.; Feibig, M.; Kivekäs, N.; Swietlicki, E.; Lihavainen, H.; Asmi, E.; Ulevicius, V.; Aalto, P.P.; Mihalopoulos, N.; Kalivitis, N.; Kalapov, I.; Kiss, G.; de Leeuw, G.; Henzing, B.; O'Dowd, C.; Jennings, S.G.; Flentje, H.; Meinhardt, F.; Ries, L.; Denier van der Gon19, H.A.C.; Visschedijk, A.J.H.; Swietlicki, E.

    2014-01-01

    Roč. 14, č. 8 (2014), s. 4327-4348. ISSN 1680-7316 EU Projects: European Commission(XE) 36833 - EUCAARI; European Commission(XE) 26140 - EUSAAR Institutional support: RVO:67985858 Keywords : particle size distribution * clusters * aerosol size distribution Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.053, year: 2014

  15. Size Distribution of Inorganic Species and Their Inhaled Dose in a Detergent Industrial Workplace

    International Nuclear Information System (INIS)

    Aerosol particles in the workplace of a detergent industry were sampled during July 2005 by a Berner low-pressure impactor. The samples were analyzed by atomic absorption spectrometry and ion chromatography in order to determine the size distribution of metallic elements and water-soluble inorganic ions. The size distributions of some characteristic metallic elements (Cu, Fe, Al) were unimodal with their maximum found in coarse particles. Among the water-soluble aerosol components SO4+, NO3-, Cl-, NH4+ and Ca++ were the major contributors to total particle mass. The lung deposition resulting from the partially hygroscopic aerosol is estimated. The calculated lung deposition reveals the impact of separate chemical aerosol compounds on the levels of the inhaled dose. The differences observed between the total and regional deposition of the different compounds appear mainly due to their different size distributions

  16. Physicochemical Characterization of Capstone Depleted Uranium Aerosols I: Uranium Concentration in Aerosols as a Function of Time and Particle Size

    International Nuclear Information System (INIS)

    During the Capstone Depleted Uranium (DU) Aerosol Study, aerosols containing depleted uranium were produced inside unventilated armored vehicles (i.e., Abrams tanks and Bradley Fighting Vehicles) by perforation with large-caliber DU penetrators. These aerosols were collected and characterized, and the data were subsequently used to assess human health risks to personnel exposed to DU aerosols. The DU content of each aerosol sample was first quantified by radioanalytical methods, and selected samples, primarily those from the cyclone separator grit chambers, were analyzed radiochemically. Deposition occurred inside the vehicles as particles settled on interior surfaces. Settling rates of uranium from the aerosols were evaluated using filter cassette samples that collected aerosol as total mass over eight sequential time intervals. A moving filter was used to collect aerosol samples over time particularly within the first minute after the shot. The results demonstrate that the peak uranium concentration in the aerosol occurred in the first 10 s, and the concentration decreased in the Abrams tank shots to about 50% within 1 min and to less than 2% 30 min after perforation. In the Bradley vehicle, the initial (and maximum) uranium concentration was lower than those observed in the Abrams tank and decreased more slowly. Uranium mass concentrations in the aerosols as a function of particle size were evaluated using samples collected in the cyclone samplers, which collected aerosol continuously for 2 h post perforation. The percentages of uranium mass in the cyclone separator stages from the Abrams tank tests ranged from 38% to 72% and, in most cases, varied with particle size, typically with less uranium associated with the smaller particle sizes. Results with the Bradley vehicle ranged from 18% to 29% and were not specifically correlated with particle size

  17. Physicochemical characterization of Capstone depleted uranium aerosols I: uranium concentration in aerosols as a function of time and particle size.

    Science.gov (United States)

    Parkhurst, Mary Ann; Cheng, Yung Sung; Kenoyer, Judson L; Traub, Richard J

    2009-03-01

    During the Capstone Depleted Uranium (DU) Aerosol Study, aerosols containing DU were produced inside unventilated armored vehicles (i.e., Abrams tanks and Bradley Fighting Vehicles) by perforation with large-caliber DU penetrators. These aerosols were collected and characterized, and the data were subsequently used to assess human health risks to personnel exposed to DU aerosols. The DU content of each aerosol sample was first quantified by radioanalytical methods, and selected samples, primarily those from the cyclone separator grit chambers, were analyzed radiochemically. Deposition occurred inside the vehicles as particles settled on interior surfaces. Settling rates of uranium from the aerosols were evaluated using filter cassette samples that collected aerosol as total mass over eight sequential time intervals. A moving filter was used to collect aerosol samples over time, particularly within the first minute after a shot. The results demonstrate that the peak uranium concentration in the aerosol occurred in the first 10 s after perforation, and the concentration decreased in the Abrams tank shots to about 50% within 1 min and to less than 2% after 30 min. The initial and maximum uranium concentrations were lower in the Bradley vehicle than those observed in the Abrams tank, and the concentration levels decreased more slowly. Uranium mass concentrations in the aerosols as a function of particle size were evaluated using samples collected in a cyclone sampler, which collected aerosol continuously for 2 h after perforation. The percentages of uranium mass in the cyclone separator stages ranged from 38 to 72% for the Abrams tank with conventional armor. In most cases, it varied with particle size, typically with less uranium associated with the smaller particle sizes. Neither the Abrams tank with DU armor nor the Bradley vehicle results were specifically correlated with particle size and can best be represented by their average uranium mass concentrations of 65

  18. Influence of Size Effects on Concentration of Impurity (Dopant) in Aerosol Nanoparticles Growing in Supersaturated Vapor

    Czech Academy of Sciences Publication Activity Database

    Levdansky, Valerij Vladimirovič; Smolík, Jiří; Ždímal, Vladimír; Moravec, Pavel

    -: Italian Aerosol Society, 2015. ISBN N. [European Aerosol Conference EAC 2015. Milano (IT), 06.09.2015-11.09.2015] R&D Projects: GA ČR(CZ) GBP503/12/G147 Institutional support: RVO:67985858 Keywords : aerosol * nanoparticles * size effects Subject RIV: DN - Health Impact of the Environment Quality

  19. Characterization of Filter Materials for Aerosol Research – Size Resolved Penetration

    Czech Academy of Sciences Publication Activity Database

    Ondráček, Jakub; Zíková, Naděžda; Ždímal, Vladimír

    Prague: Czech Aerosol Society, 2013, C068. ISBN N. [European Aerosol Conference (EAC 2013). Prague (CZ), 01.09.2013-06.09.2013] R&D Projects: GA MV VF2011201513 Institutional support: RVO:67985858 Keywords : size resolved penetration * aerosol filter s * home-made filter tester Subject RIV: CF - Physical ; Theoretical Chemistry http://eac2013.cz/index.php

  20. Phase doppler anemometer - commissioning tests for measurement of water aerosol sizes and velocities in flashing jets

    International Nuclear Information System (INIS)

    A state-of-the-art phase Doppler Anemometer (PDA) has been commissioned at AECL Research, Whiteshell Laboratories to undertake the measurement of size and velocity of water droplets generated in flashing jets. Experimental data on size and velocity distribution of water aerosols in flashing jets are required to support licensing of current multi-unit and single-unit CANDU (CANada Deuterium Uranium) stations. This paper presents the methodology involved in choosing the magnitudes of the various operating parameters of the PDA such as laser power and sensitivity of photomultiplier tubes in obtaining the experimental data. The various calibration and validation procedures used are also discussed. Size and velocity distributions in a typical flashing jet are presented. (author)

  1. Particle size distribution of halogenated flame retardants and implications for atmospheric deposition and transport.

    Science.gov (United States)

    Okonski, Krzysztof; Degrendele, Céline; Melymuk, Lisa; Landlová, Linda; Kukučka, Petr; Vojta, Šimon; Kohoutek, Jiří; Čupr, Pavel; Klánová, Jana

    2014-12-16

    This study investigates the distribution of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD) and a group of novel flame retardants (NFRs) on atmospheric aerosols. Two high volume cascade impactors were used to collect particulate fractions of ambient air over a one year period at urban and rural sites. The majority of FRs were found on the finest aerosols (<0.95 μm). Concentrations of HBCD were higher than those of ΣPBDEs. Moreover, we noted seasonality and spatial differences in particle size distributions, yet a large portion of the observed differences were due to differences in particulate matter (PM) itself. When normalized by PM, the size distributions of the FRs exhibited much greater heterogeneity. Differences existed between the FR distributions by molecular weight, with the higher molecular weight FRs (e.g., BDE-209, Dechlorane Plus) distributed more uniformly across all particulate size fractions. The seasonal, spatial, and compound-specific differences are of crucial importance when estimating dry and wet deposition of FRs as smaller aerosols have longer atmospheric residence times. Estimated wet and dry deposition of four representative FRs (BDE-47, BDE-209, HBCD, and Dechlorane Plus) using size-segregated aerosol data resulted in lower deposition estimates than when bulk aerosol data were used. This has implications for estimates of long-range atmospheric transport and atmospheric residence times, as it suggests that without size-specific distributions, these parameters could be underestimated for FRs. PMID:25380095

  2. Regularized inversion method for retrieving aerosol size distribution based on volume scattering function data at near-infrared waveband%基于近红外体散射数据的气溶胶尺度谱正则化反演方法

    Institute of Scientific and Technical Information of China (English)

    胡帅; 高太长; 李浩; 刘磊; 陈锦源; 李云

    2015-01-01

    基于0.86μm波段气溶胶的体散射数据,提出了一种新的尺度谱反演方法。根据大气气溶胶尺度谱特征,将尺度谱函数n(r)分解为趋势变化函数H(r)和细节变化函数(r),并构造了一组新的基函数对(r)进行参数化逼近,然后严格依照Mie散射理论,采用Tikhonov正则化对尺度谱函数进行了反演。采用城市型、乡村型和海洋型气溶胶的尺度谱实测数据进行反演仿真,结果表明,在粒径0.2~10μm区间、噪声不大于50%的条件下,实际与反演的尺度谱曲线相关系数高于0.98,表现出良好的抗噪声能力;针对小尺寸段(r<0.2μm)反演结果的不稳定性,提出了小尺寸段的荣格分布修正法与细模态参数补偿法,模拟结果表明,两种方法对尺度谱修正效果较理想,在0.1~10μm区间,实际与反演尺度谱曲线相关系数大于0.97。与基于遗传算法的尺度谱反演方法相比,该方法效率高,耗时短,且对尺度谱函数细节变化特征反演较好。%Based on volume scattering data at 0.86 μm, a new method for retrieving aerosol size distribution functions was put forward. According to the characteristics of aerosol size distribution, size distribution function n (r) was broken into two part, whole-trend function H (r) and detail-describing function (r), and a new series of basis functions were advanced and employed to approach (r). To overcome ill-posed nature in retrieval process, Tikhonov regularization method was combined with Mie scattering theory to strengthen the capabilities to void the influence of measurement noise and errors caused by numerical integration. Retrieval simulations are performed with size distribution data measured by Anhui Institute of Optics and Fine Mechanics, which represents three different kinds of aerosol, urban, rural and oceanic. Results show that, when radius of particles is larger than 0.2 μm, the curve of retrieved size distribution

  3. Distribution of pollutant aerosols in Mexico City

    International Nuclear Information System (INIS)

    The ecological and toxicological effects in the environment are mainly governed by concentrations of different chemical element constituents dispersed as aerosols in the atmosphere so, their analysis is very important. Analysis of the aerosols samples collected with a cascade impactor or a filter unit was simplified by using ion beam analytical techniques. Data collected routinely at regular intervals throughout the year and during special seasonal periods is the supporting statistical material by which the behavior of the elements concentrations can be observed. The PIXE technique was used in these studies for analysing samples collected in the spring of 1988 and others taken once weekly in the same year. Here the results are presented and discussed. (Author)

  4. Sensitivity of tropospheric chemical composition to halogen-radical chemistry using a fully coupled size-resolved multiphase chemistry/global climate system – Part 1: Halogen distributions, aerosol composition, and sensitivity of climate-relevant gases

    Directory of Open Access Journals (Sweden)

    M. S. Long

    2013-03-01

    Full Text Available Observations and model studies suggest a significant but highly non-linear role for halogens, primarily Cl and Br, in multiphase atmospheric processes relevant to tropospheric chemistry and composition, aerosol evolution, radiative transfer, weather, and climate. The sensitivity of global atmospheric chemistry to the production of marine aerosol and the associated activation and cycling of inorganic Cl and Br was tested using a size-resolved multiphase coupled chemistry/global climate model (National Center for Atmospheric Research's Community Atmosphere Model (CAM; v3.6.33. Simulation results showed strong meridional and vertical gradients in Cl and Br species. The simulation reproduced most available observations with reasonable confidence permitting the formulation of potential mechanisms for several previously unexplained halogen phenomena including the enrichment of Br− in submicron aerosol, and the presence of a BrO maximum in the polar free troposphere. However, simulated total volatile Br mixing ratios were generally high in the troposphere. Br in the stratosphere was lower than observed due to the lack of long-lived organobromine species in the simulation. Comparing simulations using chemical mechanisms with and without reactive Cl and Br species demonstrated a significant temporal and spatial sensitivity of primary atmospheric oxidants (O3, HOx, NOx, CH4, and non-methane hydrocarbons (NMHC's to halogen cycling. Simulated O3 and NOx were globally lower (65% and 35%, respectively, less in the planetary boundary layer based on median values in simulations that included halogens. Globally, little impact was seen in SO2 and non-sea-salt SO42− processing due to halogens. Significant regional differences were evident: the lifetime of nss-SO42− was extended downwind of large sources of SO2. The burden and lifetime of DMS (and its oxidation products were lower by a factor of 5 in simulations that included halogens, versus those without

  5. Variability of aerosol vertical distribution in the Sahel

    Directory of Open Access Journals (Sweden)

    O. Cavalieri

    2010-07-01

    Full Text Available We present and discuss ground-based and satellite observations of aerosol optical properties over Sahelian Africa for the years 2006, 2007 and 2008.

    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 Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO.

    The 2006 seasonal pattern of the aerosols vertical distribution is presented. It shows the presence of aerosol mainly confined in the lower levels of the atmosphere during the dry season, with the aerosol layer increasing in vertical extension and absolute values in spring, reaching the largest values in summer in correspondence with a progressive clearing up of the atmosphere at the lowermost levels.

    Aerosol produced by biomass burning are observed mainly during the dry season, when north-easterly air masses pass over large biomass burning areas before recirculating over the measurement sites. This kind of aerosol is present mainly in layers between 2 and 6 km of altitude, although episodically it may show also below 2 km, as observed in Banizoumbou (Niger in 2006. 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 continent by the monsoon flow.

    The summer season on the whole is characterized by a large presence of desert dust along the entire Sahelian region, widespread in altitude with Aerosol Optical Depths above 0.2.

    The interannual variability in the three year monitoring period is not very significant. An analysis of the aerosol

  6. Equilibrium size distribution of rouleaux

    Energy Technology Data Exchange (ETDEWEB)

    Perelson, A.S. (Los Alamos National Lab., NM); Wiegel, F.W.

    1982-02-01

    Rouleaux are formed by the aggregation of red blood cells in the presence of macromolecules that bridge the membranes of adherent erythrocytes. We compute the size and degree of branching of rouleaux for macroscopic systems in thermal equilibrium in the absence of fluid flow. Using techniques from statistical mechanics, analytical expressions are derived for (a) the average number of rouleaux consisting of n cells and having m branch points; (b) the average number of cells per rouleau; (c) the average number of branch points per rouleau; and (d) the number of rouleaux with n cells, n = 1, 2,..., in a system containing a total of N cells. We also present the results of numerical evaluations to establish the validity of asymptotic expressions that simplify our formal analytic results.

  7. Experimental determination of size distributions: analyzing proper sample sizes

    Science.gov (United States)

    Buffo, A.; Alopaeus, V.

    2016-04-01

    The measurement of various particle size distributions is a crucial aspect for many applications in the process industry. Size distribution is often related to the final product quality, as in crystallization or polymerization. In other cases it is related to the correct evaluation of heat and mass transfer, as well as reaction rates, depending on the interfacial area between the different phases or to the assessment of yield stresses of polycrystalline metals/alloys samples. The experimental determination of such distributions often involves laborious sampling procedures and the statistical significance of the outcome is rarely investigated. In this work, we propose a novel rigorous tool, based on inferential statistics, to determine the number of samples needed to obtain reliable measurements of size distribution, according to specific requirements defined a priori. Such methodology can be adopted regardless of the measurement technique used.

  8. Universality of rain event size distributions

    CERN Document Server

    Peters, O; Corral, A; Neelin, J D; Holloway, C E

    2010-01-01

    We compare rain event size distributions derived from measurements in climatically different regions, which we find to be well approximated by power laws of similar exponents over broad ranges. Differences can be seen in the large-scale cutoffs of the distributions. Event duration distributions suggest that the scale-free aspects are related to the absence of characteristic scales in the meteorological mesoscale.

  9. Universality of rain event size distributions

    International Nuclear Information System (INIS)

    We compare rain event size distributions derived from measurements in climatically different regions, which we find to be well approximated by power laws of similar exponents over broad ranges. Differences can be seen in the large-scale cutoffs of the distributions. Event duration distributions suggest that the scale-free aspects are related to the absence of characteristic scales in the meteorological mesoscale

  10. Size distribution of trace metals in Ponce, Puerto Rico air particulate matter

    Science.gov (United States)

    Infante, Rafael; Acosta, Iris L.

    The atmospheric particulate size distribution of nine heavy metals was measured in Ponce, a moderately industrial city in the south of Puerto Rico. Samples were collected in the city center and outlying suburban and rural locations during 1986. The size measurements were done with a cascade impactor. The elemental content of the size fractionated aerosol samples was determined by inductively coupled plasma atomic emission spectroscopy. The particle size distributions observed for Cu, Cd, Pb, Mn and Fe were bimodal with a gradual progression from mainly coarse mode to mainly fine mode. Al, Ni and Zn were mostly associated with coarse particles and V size distribution was unimodal with maxima associated with fine particles. The particle size distribution did not vary significantly with the sites sampled in the urban area although some regional characteristics are observed. The data obtained strongly suggest motor vehicle traffic and fuel combustion as the principal pollution pources in Ponce aerosol.

  11. Aggregate size distributions in sweep flocculation

    Directory of Open Access Journals (Sweden)

    Chairoj Rattanakawin

    2005-09-01

    Full Text Available The evolution of aggregate size distributions resulting from sweep flocculation has been investigated using laser light scattering technique. By measuring the (volume distributions of floc size, it is possible to distinguish clearly among floc formation, growth and breakage. Sweep flocculation of stable kaolin suspensions with ferric chloride under conditions of the rapid/slow mixing protocol produces uni-modal size distributions. The size distribution is shifted to larger floc size especially during the rapid mixing step. The variation of the distributions is also shown in the plot of cumulative percent finer against floc size. From this plot, the distributions maintain the same S-shape curves over the range of the mixing intensities/times studied. A parallel shift of the curves indicates that self-preserving size distribution occurred in this flocculation. It is suggested that some parameters from mathematical functions derived from the curves could be used to construct a model and predict the flocculating performance. These parameters will be useful for a water treatment process selection, design criteria, and process control strategies. Thus the use of these parameters should be employed in any further study.

  12. 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

  13. Model analysis of aerosol optical depth distributions over East Asia

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Based on simulated major aerosol concentrations (e.g., sulfate, nitrate, ammonium, organic carbon, black carbon, and sea salt) over East Asia during the year 2005 by using the Multi-scale Air Quality modeling system (RAMS-CMAQ), the aerosol optical depth (AOD) was calculated by the reconstruction mass-extinction method and then analyzed to explore its characteristics in temporal-spatial distributions. For evaluating the model performances, simulated AOD values were compared against observations at stations of the Aerosol Robotic Network (AERONET) and the Chinese Sun Hazemeter Network (CSHNET). The comparison shows that the model can well reproduce observed temporal and spatial features of AOD, especially in natural en- vironment. However, the simulated AOD values are underestimated over urban and suburban regions with dense human activities. Analysis of simulation results indicates that AOD varies significantly in time and space, and generally, AOD values are lower in summer and higher in winter. Excluding the contribution from soil dust aerosols, high AOD values (over 0.8) are found over the Sichuan Basin, South China, and Central China in several months, while low values (less than 0.2) are over northern and western areas of East Asia and southern sea regions. Analysis also shows that aerosols such as sulfate, nitrate, and ammonium are main contributors to AOD in East Asia, and their contributions are over 80% in most high AOD areas, while black carbon aerosols play an important role in northern China where dense human activities exist, especially in the winter time.

  14. Modelling size and structure of nanoparticles formed from drying of submicron solution aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Bandyopadhyay, Arpan A.; Pawar, Amol A.; Venkataraman, Chandra; Mehra, Anurag, E-mail: mehra@iitb.ac.in [Indian Institute of Technology Bombay, Department of Chemical Engineering (India)

    2015-01-15

    Drying of submicron solution aerosols, under controlled conditions, has been explored to prepare nanoparticles for drug delivery applications. A computational model of solution drop evaporation is developed to study the evolution of solute gradients inside the drop and predict the size and shell thickness of precipitating nanoparticles. The model considers evaporation as a two-stage process involving droplet shrinkage and shell growth. It was corroborated that droplet evaporation rate controls the solute distribution within a droplet and the resulting particle structure (solid or shell type). At higher gas temperatures, rapid build-up of solute near drop surface from high evaporation rates results in early attainment of critical supersaturation solubility and a steeper solute gradient, which favours formation of larger, shell-type particles. At lower gas temperatures, formation of smaller, solid nanoparticles is indicated. The computed size and shell thickness are in good agreement with experimentally prepared lipid nanoparticles. This study indicates that solid or shell structure of precipitated nanoparticles is strongly affected by evaporation rate, while initial solute concentration in the precursor solution and atomized droplet size affect shell thickness. For the gas temperatures considered, evaporative cooling leads to droplet temperature below the melting point of the lipid solute. Thus, we conclude that control over nanoparticle size and structure, of thermolabile precursor materials suitable for drug delivery, can be achieved by controlling evaporation rates, through selection of aerosol processing conditions.

  15. Particle size distribution instrument. Topical report 13

    Energy Technology Data Exchange (ETDEWEB)

    Okhuysen, W.; Gassaway, J.D.

    1995-04-01

    The development of an instrument to measure the concentration of particles in gas is described in this report. An in situ instrument was designed and constructed which sizes individual particles and counts the number of occurrences for several size classes. Although this instrument was designed to detect the size distribution of slag and seed particles generated at an experimental coal-fired magnetohydrodynamic power facility, it can be used as a nonintrusive diagnostic tool for other hostile industrial processes involving the formation and growth of particulates. Two of the techniques developed are extensions of the widely used crossed beam velocimeter, providing simultaneous measurement of the size distribution and velocity of articles.

  16. Effects of aerosol sources and chemical compositions on cloud drop sizes and glaciation temperatures

    Science.gov (United States)

    Zipori, Assaf; Rosenfeld, Daniel; Tirosh, Ofir; Teutsch, Nadya; Erel, Yigal

    2015-09-01

    The effect of aerosols on cloud properties, such as its droplet sizes and its glaciation temperatures, depends on their compositions and concentrations. In order to examine these effects, we collected rain samples in northern Israel during five winters (2008-2011 and 2013) and determined their chemical composition, which was later used to identify the aerosols' sources. By combining the chemical data with satellite-retrieved cloud properties, we linked the aerosol types, sources, and concentrations with the cloud glaciation temperatures (Tg). The presence of dust increased Tg from -26°C to -12°C already at relatively low dust concentrations. This result is in agreement with the conventional wisdom that desert dust serves as good ice nuclei (INs). With higher dust concentrations, Tg saturated at -12°C, even though cloud droplet sizes decreased as a result of the cloud condensation nucleating (CCN) activity of the dust. Marine air masses also encouraged freezing, but in this case, freezing was enhanced by the larger cloud droplet sizes in the air masses (caused by low CCN concentrations) and not by IN concentrations or by aerosol type. An increased fraction of anthropogenic aerosols in marine air masses caused a decrease in Tg, indicating that these aerosols served as poor IN. Anthropogenic aerosols reduced cloud droplet sizes, which further decreased Tg. Our results could be useful in climate models for aerosol-cloud interactions, as we investigated the effects of aerosols of different sources on cloud properties. Such parameterization can simplify these models substantially.

  17. Domain Size Distribution in Segregating Binary Superfluids

    Science.gov (United States)

    Takeuchi, Hiromitsu

    2016-05-01

    Domain size distribution in phase separating binary Bose-Einstein condensates is studied theoretically by numerically solving the Gross-Pitaevskii equations at zero temperature. We show that the size distribution in the domain patterns arising from the dynamic instability obeys a power law in a scaling regime according to the dynamic scaling analysis based on the percolation theory. The scaling behavior is kept during the relaxation dynamics until the characteristic domain size becomes comparable to the linear size of the system, consistent with the dynamic scaling hypothesis of the phase-ordering kinetics. Our numerical experiments indicate the existence of a different scaling regime in the size distribution function, which can be caused by the so-called coreless vortices.

  18. Comparison of Particle Number Size Distributions in Three Central European Capital Cities

    Czech Academy of Sciences Publication Activity Database

    Zíková, Naděžda; Borsós, T.; Řimnáčová, Daniela; Smolík, Jiří; Wagner, Zdeněk; Weidinger, T.; Burkart, J.; Steiner, G.; Reischl, G.; Hitzenberger, R.; Schwarz, Jaroslav; Salma, I.; Ždímal, Vladimír

    Prague : Czech Aerosol Society, 2013, A212. ISBN N. [European Aerosol Conference (EAC 2013). Prague (CZ), 01.09.2013-06.09.2013] R&D Projects: GA ČR GAP209/11/1342 Grant ostatní: HSRF(HU) K84091; WFW(AT) P19515-N20 Institutional support: RVO:67985858 Keywords : urban environment * diurnal variation * number size distribution Subject RIV: CF - Physical ; Theoretical Chemistry http://eac2013.cz/index.php

  19. Droplet size distribution in condensing flow

    OpenAIRE

    Sidin, Ryan Steeve Rodney

    2009-01-01

    In this thesis, the problem of predicting the droplet size distribution in condensing ow is in- vestigated numerically and analytically. The work focuses on two types of problems: one where condensation occurs during the transonic expansion of a vapor-mixture, and a second one where condensation takes place in a synthetic turbulent ow, reminiscent of atmospheric clouds. For single-component condensing nozzle ow, three master equations for the prediction of the droplet size distribution are ev...

  20. DISTRIBUTION OF PRODUCER SIZE IN GLOBALIZED MARKET

    OpenAIRE

    Fan, H

    2012-01-01

    Distribution of producer size in a globalized market is a complex market phenomena, which is affected by the market behavior of consumers such as the loyalty of consumers to producers and the purchasing power of consumers, as well as the trade barriers among countries. In the present paper, in order to study the distribution of producer size in the globalized market, we construct a bipartite network that consists of consumers and producers with community structure. We find that the distributi...

  1. Modelling aerosol number distributions from a vehicle exhaust with an aerosol CFD model

    Science.gov (United States)

    Albriet, B.; Sartelet, K. N.; Lacour, S.; Carissimo, B.; Seigneur, C.

    2010-03-01

    Vehicular traffic contributes significantly to the aerosol number concentrations at the local scale by emitting primary soot particles and forming secondary nucleated nanoparticles. Because of their potential health effects, more attention is paid to the traffic induced aerosol number distributions. The aim of this work is to explain the phenomenology leading to the formation and the evolution of the aerosol number distributions in the vicinity of a vehicle exhaust using numerical modelling. The emissions are representative of those of a light-duty diesel truck without a diesel particle filter. The atmospheric flow is modelled with a computational fluid dynamics (CFD) code to describe the dispersion of pollutants at the local scale. The CFD code, coupled to a modal aerosol model (MAM) describing the aerosol dynamics, is used to model the tailpipe plume of a vehicle with emissions corresponding to urban driving conditions. On the basis of available measurements in Schauer et al. (1999), three surrogate species are chosen to treat the semi-volatile organic compounds in the emissions. The model simulates the formation of the aerosol distribution in the exhaust plume of a vehicle as follows. After emission to the atmosphere, particles are formed by nucleation of sulphuric acid and water vapour depending strongly on the thermodynamic state of the atmosphere and on the dilution conditions. The semi-volatile organic compounds are critical for the rapid growth of nanoparticles through condensation. The semi-volatile organic compounds are also important for the evolution of primary soot particles and can contribute substantially to their chemical composition. The most influential parameters for particle formation are the sulphur fuel content, the semi-volatile organic emissions and also the mass and initial diameter of the soot particles emitted. The model is able to take into account the complex competition between nucleation, condensation and dilution, as well as the

  2. Mass distributions and morphological and chemical characterization of urban aerosols in the continental Balkan area (Belgrade).

    Science.gov (United States)

    Đorđević, D; Buha, J; Stortini, A M; Mihajlidi-Zelić, A; Relić, D; Barbante, C; Gambaro, A

    2016-01-01

    This work presents characteristics of atmospheric aerosols of urban central Balkans area, using a size-segregated aerosol sampling method, calculation of mass distributions, SEM/EDX characterization, and ICP/MS analysis. Three types of mass distributions were observed: distribution with a pronounced domination of coarse mode, bimodal distribution, and distribution with minimum at 1 μm describing the urban aerosol. SEM/EDX analyses have shown morphological difference and variation in the content of elements in samples. EDX spectra demonstrate that particles generally contain the following elements: Al, Ca, K, Fe, Mg, Ni, K, Si, S. Additionally, the presence of As, Br, Sn, and Zn found in air masses from southeast segment points out the anthropogenic activities most probably from mining activities in southeastern part of Serbia. The ratio Al/Si equivalent to the ratio of desert dust was associated with air masses coming from southeastern and southwestern segments, pointing to influences from North Africa and Middle East desert areas whereas the Al/Si ratio in other samples is significantly lower. In several samples, we found high values of aluminum in the nucleation mode. Samples with low share of crustal elements in the coarse mode are collected when Mediterranean air masses prevailed, while high share in the coarse mode was associated with continental air masses that could be one of the approaches for identification of the aerosol origin. Graphical abstract ᅟ. PMID:26347417

  3. Analysis of the effects of aerosol distribution in the atmosphere on surface radiative measurements

    International Nuclear Information System (INIS)

    The distribution of atmospheric aerosols in the atmosphere may have important effects on the radiative properties of the atmosphere and thereby on the climate. The Atmospheric and Geophysical Sciences Division of the Lawrence Livermore National Laboratory is working with the Atmospheric Radiation Measurements (ARM) program to advise the program as to the importance of aerosols to the ARM measurement plan. The ARM Program had established a set of goals which highlight the important areas of scientific needs associated with the understanding and prediction of global climate change. This report summarizes the initial studies performed to assess the importance and effects of atmospheric aerosols on the measurements of atmospheric radiation. To accomplish this, three interlinked models were employed which calculated the MIE parameters, averaged over the appropriate size distributions and computed the solar radiation at the surface. These models are discussed. A number of computations were performed using different aerosol scenarios and size distributions. These results are discussed and a summary of these initial calculations and future directions of research are outlined

  4. Langevin granulometry of the particle size distribution

    Science.gov (United States)

    Kákay, Attila; Gutowski, M. W.; Takacs, L.; Franco, V.; Varga, L. K.

    2004-06-01

    The problem of deriving the particle size distribution directly from superparamagnetic magnetization curves is studied by three mathematical methods: (1) least-squares deviation with regularization procedure, (2) simulated annealing and (3) genetic algorithm. Software has been developed for the latest versions of all these methods and its performance compared for various models of underlying particle size distributions (Dirac dgr-like, lognormal- and Gaussian-shaped). For single peak distributions all three methods give reasonable and similar results, but for bimodal distributions the genetic algorithm is the only acceptable one. The genetic algorithm is able to recover with the same precision both the lognormal and Gaussian single and double (mixed) model distributions. The sensitivity of the genetic algorithm—the most promising method—to uncertainty of measurements was also tested; correct peak position and its half width were recovered for Gaussian distributions, when the analysed data were contaminated with noise of up to 5% of MS.

  5. Aerosol spectral optical depths and size characteristics at a coastal industriallocation in India - effect of synoptic and mesoscale weather

    Directory of Open Access Journals (Sweden)

    K. Niranjan

    2004-06-01

    Full Text Available The aerosol spectral optical depths at ten discrete channels in the visible and near IR bands, obtained from a ground-based passive multi-wavelength solar radiometer at a coastal industrial location, Visakhapatnam, on the east coast of India, are used to study the response of the aerosol optical properties and size distributions to the changes in atmospheric humidity, wind speed and direction. It is observed that during high humidity conditions, the spectral optical depths show about 30% higher growth factors, and the size distributions show the generation of a typical new mode around 0.4 microns. The surface wind speed and direction also indicate the formation of new particles when the humid marine air mass interacts with the industrial air mass. This is interpreted in terms of new particle formation and subsequent particle growth by condensation and self-coagulation. The results obtained on the surface-size segregated aerosol mass distribution from a co-located Quartz Crystal Microbalance during different humidity conditions also show a large mass increase in the sub-micron size range with an increase in atmospheric humidity, indicating new particle formation at the sub-micron size range.

  6. Intraspecific body size frequency distributions of insects.

    Directory of Open Access Journals (Sweden)

    E Jeanne Gouws

    Full Text Available Although interspecific body size frequency distributions are well documented for many taxa, including the insects, intraspecific body size frequency distributions (IaBSFDs are more poorly known, and their variation among mass-based and linear estimates of size has not been widely explored. Here we provide IaBSFDs for 16 species of insects based on both mass and linear estimates and large sample sizes (n ≥ 100. In addition, we review the published IaBSFDs for insects, though doing so is complicated by their under-emphasis in the literature. The form of IaBSFDs can differ substantially between mass-based and linear measures. Nonetheless, in non-social insects they tend to be normally distributed (18 of 27 species or in fewer instances positively skewed. Negatively skewed distributions are infrequently reported and log transformation readily removes the positive skew. Sexual size dimorphism does not generally cause bimodality in IaBSFDs. The available information on IaBSFDs in the social insects suggests that these distributions are usually positively skewed or bimodal (24 of 30 species. However, only c. 15% of ant genera are polymorphic, suggesting that normal distributions are probably more common, but less frequently investigated. Although only 57 species, representing seven of the 29 orders of insects, have been considered here, it appears that whilst IaBSFDs are usually normal, other distribution shapes can be found in several species, though most notably among the social insects. By contrast, the interspecific body size frequency distribution is typically right-skewed in insects and in most other taxa.

  7. Intraspecific body size frequency distributions of insects.

    Science.gov (United States)

    Gouws, E Jeanne; Gaston, Kevin J; Chown, Steven L

    2011-01-01

    Although interspecific body size frequency distributions are well documented for many taxa, including the insects, intraspecific body size frequency distributions (IaBSFDs) are more poorly known, and their variation among mass-based and linear estimates of size has not been widely explored. Here we provide IaBSFDs for 16 species of insects based on both mass and linear estimates and large sample sizes (n ≥ 100). In addition, we review the published IaBSFDs for insects, though doing so is complicated by their under-emphasis in the literature. The form of IaBSFDs can differ substantially between mass-based and linear measures. Nonetheless, in non-social insects they tend to be normally distributed (18 of 27 species) or in fewer instances positively skewed. Negatively skewed distributions are infrequently reported and log transformation readily removes the positive skew. Sexual size dimorphism does not generally cause bimodality in IaBSFDs. The available information on IaBSFDs in the social insects suggests that these distributions are usually positively skewed or bimodal (24 of 30 species). However, only c. 15% of ant genera are polymorphic, suggesting that normal distributions are probably more common, but less frequently investigated. Although only 57 species, representing seven of the 29 orders of insects, have been considered here, it appears that whilst IaBSFDs are usually normal, other distribution shapes can be found in several species, though most notably among the social insects. By contrast, the interspecific body size frequency distribution is typically right-skewed in insects and in most other taxa. PMID:21479214

  8. Concentration and particle size distribution of bacterial aerosols in the cabin air of a naval vessel in the Gulf of Aden%亚丁湾海域护航舰艇舱室细菌气溶胶浓度及粒径分布变化

    Institute of Scientific and Technical Information of China (English)

    刘金凤; 苑同业; 姜美娟; 王丹丹; 陈兆艳; 梁冰

    2015-01-01

    目的:跟踪监测亚丁湾海域舰艇舱室空气微生物气溶胶浓度及粒径分布变化,为控制舰艇空气污染提供科学数据。方法采用安德森CA6型及CA2型撞击式空气采样仪,对舱室细菌气溶胶进行定量富集和粒径大小的分析。结果(1)调查区域细菌气溶胶浓度为102~103 CFU/m3。(2)51%~62%的舱室细菌气溶胶颗粒粒径大小为0.65~4.70μm。结论(1)所调查环境均处于相对较低的空气微生物污染水平,将粒径和某些条件致病菌一并作为评价因素,仍存在健康安全隐患。(2)应逐步建立各种舰船空气微生物环境的可接受污染阈值和评价体系,建立有效的净化消毒措施,以保证作业人员的健康。%Objective To monitor continuously the concentration and particle size distribution of bacterial aerosol in the cabins of a large vessel deployed in the Gulf of Aden , so as to provide scientific evidence for the control of ship air pollution .Methods With a CA6 and CA2 Andersen impact sampler , bacterial aerosol in the cabins was enriched quantively and particle sizes were analyzed accordingly .Results (1) The bacterial aerosol concentration in the survey areas was within the range of 102 -103 CFU/m3 .(2) The bacterial aerosol particle sizes in 51%-62%cabins were between 0.65 -4.7 μm.Conclusions (1) Although the microbial contamination levels in the survey area were relatively low , potential health and safety hazards still existed, provided particle sizes and certain conditional pathogenic bacteria were evaluated simutaneously .(2) Acceptable thresholds and evaluation systems for bacterial pollution in the cabin air of various ships , and effective purifying and disinfecting procedures should be established , so as to ensure the health of the ship crew .

  9. Size Resolved Measurements of Springtime Aerosol Particles over the Northern South China Sea

    Science.gov (United States)

    Atwood, Samuel A.; Reid, Jeffrey S.; Kreidenweis, Sonia M.; Cliff, Stephen S.; Zhao, Yongjing; Lin, Neng-Huei; Tsay, Si-Chee; Chu, Yu-Chi; Westphal, Douglas L.

    2012-01-01

    Large sources of aerosol particles and their precursors are ubiquitous in East Asia. Such sources are known to impact the South China Sea (henceforth SCS), a sometimes heavily polluted region that has been suggested as particularly vulnerable to climate change. To help elucidate springtime aerosol transport into the SCS, an intensive study was performed on the remote Dongsha (aka Pratas) Islands Atoll in spring 2010. As part of this deployment, a Davis Rotating-drum Uniform size-cut Monitor (DRUM) cascade impactor was deployed to collect size-resolved aerosol samples at the surface that were analyzed by X-ray fluorescence for concentrations of selected elements. HYSPLIT backtrajectories indicated that the transport of aerosol observed at the surface at Dongsha was occurring primarily from regions generally to the north and east. This observation was consistent with the apparent persistence of pollution and dust aerosol, along with sea salt, in the ground-based dataset. In contrast to the sea-level observations, modeled aerosol transport suggested that the westerly flow aloft (w700 hPa) transported smoke-laden air toward the site from regions from the south and west. Measured aerosol optical depth at the site was highest during time periods of modeled heavy smoke loadings aloft. These periods did not coincide with elevated aerosol concentrations at the surface, although the model suggested sporadic mixing of this free-tropospheric aerosol to the surface over the SCS. A biomass burning signature was not clearly identified in the surface aerosol composition data, consistent with this aerosol type remaining primarily aloft and not mixing strongly to the surface during the study. Significant vertical wind shear in the region also supports the idea that different source regions lead to varying aerosol impacts in different vertical layers, and suggests the potential for considerable vertical inhomogeneity in the SCS aerosol environment.

  10. Size resolved mass concentration and elemental composition of atmospheric aerosols over the Eastern Mediterranean area

    Directory of Open Access Journals (Sweden)

    J. Smolík

    2003-01-01

    Full Text Available A Berner low pressure impactor was used to collect size-segregated aerosol samples at Finokalia, located on the north-eastern coast of Crete, Greece during July 2000 and January 2001. Several samples were also collected during the summer campaign aboard the research vessel "AEGAIEO" in the Aegean Sea. Gravimetric analysis and inversion techniques yielded daily PM1 and PM10 mass concentrations. The samples were also analysed by PIXE giving the elemental size distributions of Al, Si, K, Ca, Ti, Mn, Fe, Sr, S, Cl, Ni, V, Cu, Cr, Zn, and Pb. The crustal elements and sea-salt had a unimodal supermicron size distribution. Sulphur was found predominantly in submicron fractions. K, V, and Ni exhibited a bimodal distribution with a submicron mode produced by forest fires and oil combustion. The anthropogenic elements had broad and not well-defined distributions. The time series for PM1 and PM10 mass and elemental concentrations showed both daily and seasonal variation. Higher mass concentrations were observed during two incursions of Saharan dust, whilst higher concentrations of S, Cu, Zn, and Pb were encountered in samples collected in air masses arriving from northern Greece or the western coast of Turkey. Elevated concentrations of chlorine were found in samples with air masses either originating above the Atlantic Ocean and arriving at Finokalia via western Europe or recirculating over the western coast of the Black Sea.

  11. Size resolved mass concentration and elemental composition of atmospheric aerosols over the eastern Mediterranean area

    Directory of Open Access Journals (Sweden)

    J. Smolik

    2003-05-01

    Full Text Available A Berner low pressure impactor was used to collect size-segregated aerosol samples at Finokalia, located on the north-eastern coast of Crete, Greece during July 2000 and January 2001. Several samples were also collected during the summer campaign aboard the research vessel "AEGAIEO" in the Aegean Sea. Gravimetric analysis and inversion techniques yielded daily PM1 and PM10 mass concentrations. Further, the samples were analysed by PIXE giving elemental size distributions of Al, Si, K, Ca, Ti, Mn, Fe, Sr, S, Cl, Ni, V, Cu, Cr, Zn, and Pb. The crustal elements and sea-salt had a unimodal supermicron size distribution. Sulphur was found predominantly in submicron fractions. K, V, and Ni exhibited bimodal distribution with a submicron mode produced by forest fires and oil combustion. The anthropogenic elements had broad and not well-defined distributions. The time series for PM1 and PM10 mass and elemental concentrations showed both daily and seasonal variation. Higher mass concentrations were observed during two incursions of Saharan dust. Higher concentrations of S, Cu, Zn, and Pb were encountered in samples collected in air masses arriving from northern Greece or the western coast of Turkey. Higher concentrations of chlorine were found in samples with air masses either originating above the Atlantic Ocean and arriving at Finokalia via western Europe or recirculating over the western coast of the Black Sea.

  12. Development of the RAQM2 aerosol chemical transport model and predictions of the Northeast Asian aerosol mass, size, chemistry, and mixing type

    Directory of Open Access Journals (Sweden)

    M. Kajino

    2012-12-01

    Full Text Available A new aerosol chemical transport model, the Regional Air Quality Model 2 (RAQM2, was developed to simulate the Asian air quality. We implemented a simple version of a triple-moment modal aerosol dynamics model (MADMS and achieved a completely dynamic (non-equilibrium solution of a gas-to-particle mass transfer over a wide range of aerosol diameters from 1 nm to super-μm. To consider a variety of atmospheric aerosol properties, a category approach was utilized in which the aerosols were distributed into four categories: particles in the Aitken mode (ATK, soot-free particles in the accumulation mode (ACM, soot aggregates (AGR, and particles in the coarse mode (COR. The aerosol size distribution in each category is characterized by a single mode. The condensation, evaporation, and Brownian coagulations for each mode were solved dynamically. A regional-scale simulation (Δx = 60 km was performed for the entire year of 2006 covering the Northeast Asian region. The modeled PM1/bulk ratios of the chemical components were consistent with observations, indicating that the simulated aerosol mixing types were consistent with those in nature. The non–sea-salt SO42− mixed with ATK + ACM was the largest at Hedo in summer, whereas the SOSO42− was substantially mixed with AGR in the cold seasons. Ninety-eight percent of the modeled NO3 was mixed with sea salt at Hedo, whereas 53.7% of the NO3 was mixed with sea salt at Gosan, which is located upwind toward the Asian continent. The condensation of HNO3 onto sea salt particles during transport over the ocean accounts for the difference in the NO3 mixing type at the two sites. Because the aerosol mixing type alters the optical properties and cloud condensation nuclei activity, its accurate prediction and evaluation are indispensable for aerosol

  13. Size Related Characterisation of Prague Aerosol: First Results from Winter Campaign

    Czech Academy of Sciences Publication Activity Database

    Schwarz, Jaroslav; Hovorka, J.; Havránek, Vladimír; Ždímal, Vladimír; Smolík, Jiří

    Vol. 2. Budapest, 2004, S583-S584. [European Aerosol Conference EAC 2004. Budapest (HU), 06.09.2004-10.09.2004] R&D Projects: GA ČR GA205/03/1560 Institutional research plan: CEZ:AV0Z4072921 Keywords : urban aerosol * mass size distibution * cascade impactor Subject RIV: CF - Physical ; Theoretical Chemistry

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

    International Nuclear Information System (INIS)

    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, σg of about 2; the CMD was found to increase and σg 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

  15. Online Aerosol Mass Spectrometry of Single Micrometer-Sized Particles Containing Poly(ethylene glycol)

    Energy Technology Data Exchange (ETDEWEB)

    Bogan, M J; Patton, E; Srivastava, A; Martin, S; Fergenson, D; Steele, P; Tobias, H; Gard, E; Frank, M

    2006-10-25

    Analysis of poly(ethylene glycol)(PEG)-containing particles by online single particle aerosol mass spectrometers equipped with laser desorption ionization (LDI) is reported. We demonstrate that PEG-containing particles are useful in the development of aerosol mass spectrometers because of their ease of preparation, low cost, and inherently recognizable mass spectra. Solutions containing millimolar quantities of PEGs were nebulized and, after drying, the resultant micrometer-sized PEG containing particles were sampled. LDI (266 nm) of particles containing NaCl and PEG molecules of average molecular weight <500 generated mass spectra reminiscent of mass spectra of PEG collected by other MS schemes including the characteristic distribution of positive ions (Na{sup +} adducts) separated by the 44 Da of the ethylene oxide units separating each degree of polymerization. PEGs of average molecular weight >500 were detected from particles that also contained t the tripeptide tyrosine-tyrosine-tyrosine or 2,5-dihydroxybenzoic acid, which were added to nebulized solutions to act as matrices to assist LDI using pulsed 266 nm and 355 nm lasers, respectively. Experiments were performed on two aerosol mass spectrometers, one reflectron and one linear, that each utilize two time-of-flight mass analyzers to detect positive and negative ions created from a single particle. PEG-containing particles are currently being employed in the optimization of our bioaerosol mass spectrometers for the application of measurements of complex biological samples, including human effluents, and we recommend that the same strategies will be of great utility to the development of any online aerosol LDI mass spectrometer platform.

  16. Nano size Aerosols of Radon Decay Products in Various Environments

    International Nuclear Information System (INIS)

    The radioactive noble gas radon (222Rn, alpha decay, t1/2 = 3.82 days) is always accompanied by its short-lived decay products (RnDP): 218Po (alpha decay, t1/2 = 3.10 min), 214Pb (beta/gamma decay, t1/2 = 26.8 min), 214Bi (beta/gamma decay, t1/2 = 19.9 min), and 214Po (alpha decay, t1/2 = 164 μs). In indoor and outdoor air, they appear as unattached RnDP in the form of clusters in the size range 0.5-3 nm and as attached RnDP between 200 and 800 nm. Because of plate-out of aerosols on the walls and floor of a room, as well as air movement and entry of fresh air, radioactive equilibrium between RnDP and Rn in indoor air is only partly achieved and is expressed as a fraction between 0 and 1, called the equilibrium factor, F. Birchall and James elaborated a dosimetric approach to calculate the dose conversion factor, DCFD, based on fun. In this paper, the results of our studies on fun in 29 rooms of kindergartens and 26 rooms of elementary and high schools, at the lowest point and the railway station in the Postojna Cave, and in 4 rooms in wineries in Slovenia are reported, and DCFD values based on the Porstendorfer formulae are discussed and compared with the DCFE value recommended by ICRP-65

  17. Aerosol optical properties at a coastal site in Hong Kong, South China: temporal features, size dependencies and source analysis

    Science.gov (United States)

    Wang, Jiaping; Ding, Aijun; Virkkula, Aki; Lee, Shuncheng; Shen, Yicheng; Chi, Xuguang; Xu, Zheng

    2016-04-01

    Hong Kong is a typical coastal city adjacent to the Pearl River Delta (PRD) region in southern China, which is one of the regions suffering from severe air pollution. Atmospheric aerosols can affect the earth's radiative balance by scattering and absorbing incoming solar radiation. Black Carbon (BC) aerosol is a particularly emphasized component due to its strong light absorption. Aerosol transported from different source areas consists of distinct size distributions, leading to different optical properties. As the byproducts of the incomplete oxidation, BC and CO both have relatively long life time, their relationship is a good indicator for distinguishing different pollutant sources. In this study, temporal variations of aerosol optical properties and concentrations of BC and CO at a coastal background station in Hong Kong were investigated. Transport characteristics and origins of aerosol were elucidated by analyzing backward Lagrangian particle dispersion modeling (LPDM) results, together with related parameters including the relationships between optical properties and particle size, BC-CO correlations, ship location data and meteorological variables. From February 2012 to September 2013 and March 2014 to February 2015, continuous in-situ measurements of light scattering and absorption coefficients, particle size distribution and concentrations of BC and CO were conducted at Hok Tsui (HT), a coastal background station on the southeast tip of Hong Kong Island (22.22°N, 114.25°E, 60 m above the sea level) with few local anthropogenic activities. Affected by the Asian monsoon, this region is dominated by continental outflow in winter and by marine inflow from the South China Sea in summer, which is an ideal station for identifying the transport characteristics of aerosol and their effects on optical properties from different anthropogenic emission sources. 7-day backward Lagrangian particle dispersion modeling was performed for source identification. Three

  18. The generation of diesel exhaust particle aerosols from a bulk source in an aerodynamic size range similar to atmospheric particles

    Directory of Open Access Journals (Sweden)

    Daniel J Cooney

    2008-08-01

    Full Text Available Daniel J Cooney1, Anthony J Hickey21Department of Biomedical Engineering; 2School of Pharmacy, University of North Carolina, Chapel Hill, NC, USAAbstract: The influence of diesel exhaust particles (DEP on the lungs and heart is currently a topic of great interest in inhalation toxicology. Epidemiological data and animal studies have implicated airborne particulate matter and DEP in increased morbidity and mortality due to a number of cardiopulmonary diseases including asthma, chronic obstructive pulmonary disorder, and lung cancer. The pathogeneses of these diseases are being studied using animal models and cell culture techniques. Real-time exposures to freshly combusted diesel fuel are complex and require significant infrastructure including engine operations, dilution air, and monitoring and control of gases. A method of generating DEP aerosols from a bulk source in an aerodynamic size range similar to atmospheric DEP would be a desirable and useful alternative. Metered dose inhaler technology was adopted to generate aerosols from suspensions of DEP in the propellant hydrofluoroalkane 134a. Inertial impaction data indicated that the particle size distributions of the generated aerosols were trimodal, with count median aerodynamic diameters less than 100 nm. Scanning electron microscopy of deposited particles showed tightly aggregated particles, as would be expected from an evaporative process. Chemical analysis indicated that there were no major changes in the mass proportion of 2 specific aromatic hydrocarbons (benzo[a]pyrene and benzo[k]fluoranthene in the particles resulting from the aerosolization process.Keywords: diesel exhaust particles, aerosol, inhalation toxicology

  19. Synthesis of nanoparticles in a flame aerosol reactor with independent and strict control of their size, crystal phase and morphology

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Jingkun; Chen, D-R; Biswas, Pratim [Aerosol and Air Quality Research Laboratory, Department of Energy, Environmental and Chemical Engineering, Washington University in St Louis, Campus Box 1180, St Louis, MO 63130 (United States)

    2007-07-18

    A flame aerosol reactor (FLAR) was developed to synthesize nanoparticles with desired properties (crystal phase and size) that could be independently controlled. The methodology was demonstrated for TiO{sub 2} nanoparticles, and this is the first time that large sets of samples with the same size but different crystal phases (six different ratios of anatase to rutile in this work) were synthesized. The degree of TiO{sub 2} nanoparticle agglomeration was determined by comparing the primary particle size distribution measured by scanning electron microscopy (SEM) to the mobility-based particle size distribution measured by online scanning mobility particle spectrometry (SMPS). By controlling the flame aerosol reactor conditions, both spherical unagglomerated particles and highly agglomerated particles were produced. To produce monodisperse nanoparticles, a high throughput multi-stage differential mobility analyser (MDMA) was used in series with the flame aerosol reactor. Nearly monodisperse nanoparticles (geometric standard deviation less than 1.05) could be collected in sufficient mass quantities (of the order of 10 mg) in reasonable time (1 h) that could be used in other studies such as determination of functionality or biological effects as a function of size.

  20. Use of stable carbon and nitrogen isotope ratios in size segregated aerosol particles for the O/I penetration evaluation

    Science.gov (United States)

    Garbaras, Andrius; Garbariene, Inga; Masalaite, Agne; Ceburnis, Darius; Krugly, Edvinas; Kvietkus, Kestutis; Remeikis, Vidmantas; Martuzevicius, Dainius

    2015-04-01

    Stable carbon and nitrogen isotope ratio are successfully used in the atmospheric aerosol particle source identification [1, 2], transformation, pollution [3] research. The main purpose of this study was to evaluate the penetration of atmospheric aerosol particles from outdoor to indoor using stable carbon and nitrogen isotope ratios. Six houses in Kaunas (Lithuania) were investigated during February and March 2013. Electrical low pressure impactor was used to measure in real time concentration and size distribution of outdoor aerosol particles. ELPI+ includes 15 channels covering the size range from 0.017 to 10.0 µm. The 25 mm diameter aluminium foils were used to collect aerosol particles. Gravimetric analysis of samples was made using microbalance. In parallel, indoor aerosol samples were collected with a micro-orifice uniform deposition impactor (MOUDI model 110), where the aerosol particles were separated with the nominal D50 cut-off sizes of 0.056, 0.1, 0.18,0.32,0.56, 1.0, 1.8, 3.2, 5.6, 10, 18 μm for impactor stages 1-11, respectively. The impactor was run at a flow rate of 30 L/min. Air quality meters were used to record meteorological conditions (temperature, relative humidity) during the investigated period. All aerosol samples were analyzed for total carbon (TC) and total nitrogen (TN) contents and their isotopic compositions using elemental analyzer (EA) connected to the stable isotope ratio mass spectrometer (IRMS). TC concentration in indoors ranged from 1.5 to 247.5 µg/m3. During the sampling period outdoors TN levels ranged from 0.1 to 10.9 µg/m3. The obtained outdoor δ13C(PM2.5) values varied from -24.21 to -26.3‰, while the δ15N values varied from 2.4 to 11.1 ‰ (average 7.2±2.5 ‰). Indoors carbonaceous aerosol particles were depleted in 13C compared to outdoors in all sampling sites. This depletion in δ13C varied from 0.1 to 3.2 ‰. We think that this depletion occurs due ongoing chemical reactions (oxidation) when aerosol

  1. Sequential Testing with Uniformly Distributed Size

    OpenAIRE

    Stanislav Anatolyev; Grigory Kosenok

    2011-01-01

    Sequential procedures of testing for structural stability do not provide enough guidance on the shape of boundaries that are used to decide on acceptance or rejection, requiring only that the overall size of the test is asymptotically controlled. We introduce and motivate a reasonable criterion for a shape of boundaries which requires that the test size be uniformly distributed over the testing period. Under this criterion, we numerically construct boundaries for most popular sequential tests...

  2. Emission factors of carbon monoxide and size-resolved aerosols from biofuel combustion.

    Science.gov (United States)

    Venkataraman, C; Rao, G U

    2001-05-15

    This study reports emission factors of carbon monoxide and size-resolved aerosols from combustion of wood, dung cake, and biofuel briquette in traditional and improved stoves in India. Wood was the cleanest burning fuel, with higher emissions of CO from dung cake and particulate matter from both dung cake and briquette fuels. Combustion of dung cake, especially in an improved metal stove, resulted in extremely high pollutant emissions. Instead, biogas from anaerobic dung digestion should be promoted as a cooking fuel for public health protection. Pollutant emissions increased with increasing stove thermal efficiency, implying that thermal efficiency enhancement in the improved stoves was mainly from design features leading to increased heat transfer but not combustion efficiency. Compared to the traditional stove, the improved stoves resulted in the lower pollutant emissions on a kW h-1 basis from wood combustion but in similar emissions from briquette and dung cake. Stove designs are needed with good emissions performance across multiple fuels. Unimodal aerosol size distributions were measured from biofuel combustion with mass median aerodynamic diameters of 0.5-0.8 micron, about a factor of 10 larger than those from fossil fuel combustion (e.g. diesel), with potential implications for lung deposition and health risk. PMID:11393993

  3. Fluctuations and intermittency in fragment size distributions

    International Nuclear Information System (INIS)

    The intermittency signal on the size frequency of fragments found in various fragmenting systems is reconsidered. This signal extracted from a factorial moment analysis was interpreted as a genuine intermittency. The conclusion is that the signal found in earlier works and interpreted as an intermittency behaviour results from both the power law of the mean size fragment distribution and from the finite width of the multiplicity distribution. Any partition of integers exhibiting these two features will provide a similar signal. (author). 38 refs., 9 figs

  4. Evaluation and modeling of the size fractionated aerosol particle number concentration measurements nearby a major road in Helsinki ─ Part II: Aerosol measurements within the SAPPHIRE project

    Directory of Open Access Journals (Sweden)

    A. Karppinen

    2007-08-01

    Full Text Available This study presents an evaluation and modeling exercise of the size fractionated aerosol particle number concentrations measured nearby a major road in Helsinki during 23 August–19 September 2003 and 14 January–11 February 2004. The available information also included electronic traffic counts, on-site meteorological measurements, and urban background particle number size distribution measurement. The ultrafine particle (UFP, diameter<100 nm number concentrations at the roadside site were approximately an order of magnitude higher than those at the urban background site during daytime and downwind conditions. Both the modal structure analysis of the particle number size distributions and the statistical correlation between the traffic density and the UFP number concentrations indicate that the UFP were evidently from traffic related emissions. The modeling exercise included the evolution of the particle number size distribution nearby the road during downwind conditions. The model simulation results revealed that the evaluation of the emission factors of aerosol particles might not be valid for the same site during different time.

  5. Sustained distribution of aerosolized PEGylated liposomes in epithelial lining fluids on alveolar surfaces.

    Science.gov (United States)

    Kaneko, Keita; Togami, Kohei; Yamamoto, Eri; Wang, Shujun; Morimoto, Kazuhiro; Itagaki, Shirou; Chono, Sumio

    2016-10-01

    The distribution characteristics of aerosolized PEGylated liposomes in alveolar epithelial lining fluid (ELF) were examined in rats, and the ensuing mechanisms were investigated in the in vitro uptake and protein adsorption experiments. Nonmodified or PEGylated liposomes (particle size 100 nm) were aerosolized into rat lungs. PEGylated liposomes were distributed more sustainably in ELFs than nonmodified liposomes. Furthermore, the uptake of PEGylated liposomes by alveolar macrophages (AMs) was less than that of nonmodified liposomes. In further in vitro uptake experiments, nonmodified and PEGylated liposomes were opsonized with rat ELF components and then added to NR8383 cells as cultured rat AMs. The uptake of opsonized PEGylated liposomes by NR8383 cells was lower than that of opsonized nonmodified liposomes. Moreover, the protein absorption levels in opsonized PEGylated liposomes were lower than those in opsonized nonmodified liposomes. These findings suggest that sustained distributions of aerosolized PEGylated liposomes in ELFs reflect evasion of liposomal opsonization with surfactant proteins and consequent reductions in uptake by AMs. These data indicate the potential of PEGylated liposomes as aerosol-based drug delivery system that target ELF for the treatment of respiratory diseases. PMID:27334278

  6. Study on long-term aerosol distribution over the land of East China using MODIS data

    OpenAIRE

    Q. He; C Li; F. Geng; Lei, Y.; Li, Y.; X. Tie; Yin, Q.

    2011-01-01

    East China is among the fastest developing and most populous area in Asia, where atmospheric aerosol loading is high due to heavy urban and industrial emission. These aerosols may have significant impact on regional climate and environment. In this report, MODIS level 2 aerosol products (2000–2007) were used to study aerosol spatial and temporal distributions, as well as their variations with local meteorological conditions over East China. By combining Aerosol Optical Depth...

  7. The size-distribution of Earth's lakes.

    Science.gov (United States)

    Cael, B B; Seekell, D A

    2016-01-01

    Globally, there are millions of small lakes, but a small number of large lakes. Most key ecosystem patterns and processes scale with lake size, thus this asymmetry between area and abundance is a fundamental constraint on broad-scale patterns in lake ecology. Nonetheless, descriptions of lake size-distributions are scarce and empirical distributions are rarely evaluated relative to theoretical predictions. Here we develop expectations for Earth's lake area-distribution based on percolation theory and evaluate these expectations with data from a global lake census. Lake surface areas ≥8.5 km(2) are power-law distributed with a tail exponent (τ = 1.97) and fractal dimension (d = 1.38), similar to theoretical expectations (τ = 2.05; d = 4/3). Lakes distributed. An independently developed regional lake census exhibits a similar transition and consistency with theoretical predictions. Small lakes deviate from the power-law distribution because smaller lakes are more susceptible to dynamical change and topographic behavior at sub-kilometer scales is not self-similar. Our results provide a robust characterization and theoretical explanation for the lake size-abundance relationship, and form a fundamental basis for understanding and predicting patterns in lake ecology at broad scales. PMID:27388607

  8. International intercalibration and intercomparison measurements of radon progeny particle size distribution

    International Nuclear Information System (INIS)

    Because there is no standard method for 222Rn progeny size measurements, verifying the performance of various measurement techniques is important. This report describes results of an international intercomparison and calibration of 222Rn progeny size measurements involving low pressure impactors (MOUDI and Berner) and diffusion battery systems, as well as both alpha- and gamma- counting methods. The intercomparison was at EML on June 12-15, 1995. 5 different particle sizes (80, 90, 165, 395, 1200 nm) of near monodisperse condensation Carbauba wax aerosol and 2 bimodal size spectra (160 and 365 nm, and 70 and 400 nm) were used. 20 tests were completed, covering both low and high concentrations of 222Rn and test aerosols. For the single-mode test aerosol, the measurements agreed within the size range. Best agreement was found between the two low pressure impactors. Some differences between the impactor and diffusion battery methods were observed in the specific peak locations and the resultant geometric mean diameters. For the two bimodal size distribution aerosols, the MOUDI measurements showed two modes, while the other 3 devices showed a single mode size distribution

  9. International intercalibration and intercomparison measurements of radon progeny particle size distribution

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Keng-Wu

    1997-07-01

    Because there is no standard method for {sup 222}Rn progeny size measurements, verifying the performance of various measurement techniques is important. This report describes results of an international intercomparison and calibration of {sup 222}Rn progeny size measurements involving low pressure impactors (MOUDI and Berner) and diffusion battery systems, as well as both alpha- and gamma- counting methods. The intercomparison was at EML on June 12-15, 1995. 5 different particle sizes (80, 90, 165, 395, 1200 nm) of near monodisperse condensation Carbauba wax aerosol and 2 bimodal size spectra (160 and 365 nm, and 70 and 400 nm) were used. 20 tests were completed, covering both low and high concentrations of {sup 222}Rn and test aerosols. For the single-mode test aerosol, the measurements agreed within the size range. Best agreement was found between the two low pressure impactors. Some differences between the impactor and diffusion battery methods were observed in the specific peak locations and the resultant geometric mean diameters. For the two bimodal size distribution aerosols, the MOUDI measurements showed two modes, while the other 3 devices showed a single mode size distribution.

  10. Phase, size and shape controlled formation of aerosol generated nickel and nickel oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, D., E-mail: d.ponce@ucl.ac.uk [Department of Physics and Astronomy, University College London, WC1E 6BT London (United Kingdom); London Centre for Nanotechnology, Gordon Street, WC1H 0AH London (United Kingdom); Kuznetsov, M.V. [N.P. Ogarev Mordovian State University, Saransk, Republic of Mordovia 430005 (Russian Federation); Morozov, Yu.G.; Belousova, O.V. [Institute of Structural Macrokinetics and Materials Science, Chernogolovka, Moscow Region 142432 (Russian Federation); Parkin, I.P. [Department of Chemistry, Materials Chemistry Centre, University College London, 20 Gordon Street, WC1H 0AJ London (United Kingdom)

    2013-12-05

    Highlights: •Structural and magnetic characterization of aerosol Ni nanoparticles. •Experimental parameters affecting size, shape and composition are discussed. •Larger spherical particles with the highest Ni content are produced by using an Ar flow. •Coalescence rate of primary particles is accelerated by increasing Ni feeding rate. •Ni nanoparticles show bulk-like saturation magnetization values. -- Abstract: Ferromagnetic Ni nanoparticles were formed by a levitation-jet aerosol synthesis under different gas environments and metal precursor feed rates. At a constant background gas inlet temperature, it was found that a higher Ni loading resulted in enhanced particle growth through coalescence. He partial atmosphere favors surface condensation of evaporated Ni atoms over coalescence as the surface area reduction mechanism in the nanoparticles. A flow of 2.5% air in the background gas mixture was enough to oxidize 75% of the initial Ni load, inducing a drastic destabilization of particle size and shape distribution. Regardless of the background inert gas composition, necked nanoparticles were observed in samples prepared with a 1 g/h Ni feed rate, whereas discrete nanoparticles resulted from a higher feed rate of ca. 4 g/h, confirming the key role of Ni loading on the rate of coalescence. The highest saturation magnetization (51.75 A m{sup 2} kg{sup −1} measured at 300 K) and the lowest coercivity (0.008 T) were obtained under an Ar flow. Zero-field cooled and field-cooled magnetization curves measured under an applied field of 10{sup −2} T revealed that the blocking processes of nanoparticles are dominated by their particle size distributions, with some features attributable to interparticle interactions.

  11. Particle size distributions in the Eastern Mediterranean troposphere

    Science.gov (United States)

    Kalivitis, N.; Birmili, W.; Stock, M.; Wehner, B.; Massling, A.; Wiedensohler, A.; Gerasopoulos, E.; Mihalopoulos, N.

    2008-11-01

    Atmospheric particle size distributions were measured on Crete island, Greece in the Eastern Mediterranean during an intensive field campaign between 28 August and 20 October, 2005. Our instrumentation combined a differential mobility particle sizer (DMPS) and an aerodynamic particle sizer (APS) and measured number size distributions in the size range 0.018 μm 10 μm. Four time periods with distinct aerosol characteristics were discriminated, two corresponding to marine and polluted air masses, respectively. In marine air, the sub-μm size distributions showed two particle modes centered at 67 nm and 195 nm having total number concentrations between 900 and 2000 cm-3. In polluted air masses, the size distributions were mainly unimodal with a mode typically centered at 140 nm, with number concentrations varying between 1800 and 2900 cm-3. Super-μm particles showed number concentrations in the range from 0.01 to 2.5 cm-3 without any clear relation to air mass origin. A small number of short-lived particle nucleation events were recorded, where the calculated particle formation rates ranged between 1.1 1.7 cm-3 s-1. However, no particle nucleation and growth events comparable to those typical for the continental boundary layer were observed. Particles concentrations (Diameter <50 nm) were low compared to continental boundary layer conditions with an average concentration of 300 cm-3. The production of sulfuric acid and its subsequently condensation on preexisting particles was examined with the use of a simplistic box model. These calculations suggested that the day-time evolution of the Aitken particle population was governed mainly by coagulation and that particle formation was absent during most days.

  12. Raindrop Size Distribution Measurements in Tropical Cyclones

    Science.gov (United States)

    Tokay, Ali; Bashor, Paul G.; Habib, Emad; Kasparis, Takis

    2008-01-01

    Characteristics of the raindrop size distribution in seven tropical cyclones have been studied through impact-type disdrometer measurements at three different sites during the 2004-06 Atlantic hurricane seasons. One of the cyclones has been observed at two different sites. High concentrations of small and/or midsize drops were observed in the presence or absence of large drops. Even in the presence of large drops, the maximum drop diameter rarely exceeded 4 mm. These characteristics of raindrop size distribution were observed in all stages of tropical cyclones, unless the storm was in the extratropical stage where the tropical cyclone and a midlatitude frontal system had merged. The presence of relatively high concentrations of large drops in extratropical cyclones resembled the size distribution in continental thunderstorms. The integral rain parameters of drop concentration, liquid water content, and rain rate at fixed reflectivity were therefore lower in extratropical cyclones than in tropical cyclones. In tropical cyclones, at a disdrometercalculated reflectivity of 40 dBZ, the number concentration was 700 plus or minus 100 drops m(sup -3), while the liquid water content and rain rate were 0.90 plus or minus 0.05 g m(sup -3) and 18.5 plus or minus 0.5 mm h(sup -1), respectively. The mean mass diameter, on the other hand, was 1.67 plus or minus 0.3 mm. The comparison of raindrop size distributions between Atlantic tropical cyclones and storms that occurred in the central tropical Pacific island of Roi-Namur revealed that the number density is slightly shifted toward smaller drops, resulting in higher-integral rain parameters and lower mean mass and maximum drop diameters at the latter site. Considering parameterization of the raindrop size distribution in tropical cyclones, characteristics of the normalized gamma distribution parameters were examined with respect to reflectivity. The mean mass diameter increased rapidly with reflectivity, while the normalized

  13. Nanomaterial size distribution analysis via liquid nebulization coupled with ion mobility spectrometry (LN-IMS).

    Science.gov (United States)

    Jeon, Seongho; Oberreit, Derek R; Van Schooneveld, Gary; Hogan, Christopher J

    2016-02-21

    We apply liquid nebulization (LN) in series with ion mobility spectrometry (IMS, using a differential mobility analyzer coupled to a condensation particle counter) to measure the size distribution functions (the number concentration per unit log diameter) of gold nanospheres in the 5-30 nm range, 70 nm × 11.7 nm gold nanorods, and albumin proteins originally in aqueous suspensions. In prior studies, IMS measurements have only been carried out for colloidal nanoparticles in this size range using electrosprays for aerosolization, as traditional nebulizers produce supermicrometer droplets which leave residue particles from non-volatile species. Residue particles mask the size distribution of the particles of interest. Uniquely, the LN employed in this study uses both online dilution (with dilution factors of up to 10(4)) with ultra-high purity water and a ball-impactor to remove droplets larger than 500 nm in diameter. This combination enables hydrosol-to-aerosol conversion preserving the size and morphology of particles, and also enables higher non-volatile residue tolerance than electrospray based aerosolization. Through LN-IMS measurements we show that the size distribution functions of narrowly distributed but similarly sized particles can be distinguished from one another, which is not possible with Nanoparticle Tracking Analysis in the sub-30 nm size range. Through comparison to electron microscopy measurements, we find that the size distribution functions inferred via LN-IMS measurements correspond to the particle sizes coated by surfactants, i.e. as they persist in colloidal suspensions. Finally, we show that the gas phase particle concentrations inferred from IMS size distribution functions are functions of only of the liquid phase particle concentration, and are independent of particle size, shape, and chemical composition. Therefore LN-IMS enables characterization of the size, yield, and polydispersity of sub-30 nm particles. PMID:26750519

  14. Biogenic, anthropogenic and sea salt sulfate size-segregated aerosols in the Arctic summer

    Science.gov (United States)

    Ghahremaninezhad, Roghayeh; Norman, Ann-Lise; Abbatt, Jonathan P. D.; Levasseur, Maurice; Thomas, Jennie L.

    2016-04-01

    Size-segregated aerosol sulfate concentrations were measured on board the Canadian Coast Guard Ship (CCGS) Amundsen in the Arctic during July 2014. The objective of this study was to utilize the isotopic composition of sulfate to address the contribution of anthropogenic and biogenic sources of aerosols to the growth of the different aerosol size fractions in the Arctic atmosphere. Non-sea-salt sulfate is divided into biogenic and anthropogenic sulfate using stable isotope apportionment techniques. A considerable amount of the average sulfate concentration in the fine aerosols with a diameter 63 %), which is higher than in previous Arctic studies measuring above the ocean during fall ( 30 %) (Norman et al., 1999). The anthropogenic sulfate concentration was less than that of biogenic sulfate, with potential sources being long-range transport and, more locally, the Amundsen's emissions. Despite attempts to minimize the influence of ship stack emissions, evidence from larger-sized particles demonstrates a contribution from local pollution. A comparison of δ34S values for SO2 and fine aerosols was used to show that gas-to-particle conversion likely occurred during most sampling periods. δ34S values for SO2 and fine aerosols were similar, suggesting the same source for SO2 and aerosol sulfate, except for two samples with a relatively high anthropogenic fraction in particles Ocean during the productive summer months.

  15. Effects of aerosol particle size on dispersion and continuous air monitor response in a plutonium laboratory

    International Nuclear Information System (INIS)

    The effectiveness of continuous air monitors (CAMs) in protecting plutonium workers depends on the efficiency of aerosol transport from the release point to the CAM. The main processes for aerosol transport are diffusion, forced convection, and gravitational settling. The transport of particles relative to each of these processes depends on particle size. Studies have shown that activity median aerodynamic diameters for plutonium aerosols can range from less than 0.1 μm to greater than 10 μm. The purpose of this study was to characterize the influence of particle size on aerosol transport and CAM response in a plutonium laboratory. Polydisperse dioctyl sebacate oil aerosols were released from multiple locations within a plutonium laboratory at Los Alamos National Laboratory. An array of Laser Particle counters (LPCs) positioned in the laboratory measured time resolved aerosol dispersion. Aerosol concentrations were binned into two size ranges: (1) 0.5 μm to 5.0 μm, and (2) those greater than 5.0 μm. Statistical comparisons were done and the results suggested that transport efficiency was greater for smaller particles than larger particles in this laboratory. This result suggested the importance of using particles of similar physical characteristics to those of the source when doing tests to decide optimal placement of CAMs

  16. Multi sky-view 3D aerosol distribution recovery.

    Science.gov (United States)

    Aides, Amit; Schechner, Yoav Y; Holodovsky, Vadim; Garay, Michael J; Davis, Anthony B

    2013-11-01

    Aerosols affect climate, health and aviation. Currently, their retrieval assumes a plane-parallel atmosphere and solely vertical radiative transfer. We propose a principle to estimate the aerosol distribution as it really is: a three dimensional (3D) volume. The principle is a type of tomography. The process involves wide angle integral imaging of the sky on a very large scale. The imaging can use an array of cameras in visible light. We formulate an image formation model based on 3D radiative transfer. Model inversion is done using optimization methods, exploiting a closed-form gradient which we derive for the model-fit cost function. The tomography model is distinct, as the radiation source is unidirectional and uncontrolled, while off-axis scattering dominates the images. PMID:24216808

  17. Evaluation and modeling of the size fractionated aerosol number concentration measurements near a major road in Helsinki

    Directory of Open Access Journals (Sweden)

    T. Hussein

    2007-03-01

    Full Text Available This study presents an evaluation and modeling of the size fractionated aerosol number concentrations that were measured near a major road of Itäväylä in Helsinki, during 23 August – 19 September 2003 and 14 January – 11 February 2004. The measurement system contained also electronic traffic counts, on-site meteorological measurements, and urban background concentration measurements. We have evaluated the temporal variations and the dependencies on local meteorological conditions of the measured aerosol number concentrations and size distributions. The ultrafine particle (UFP number concentrations at the roadside site were approximately an order of magnitude higher than those at the urban background site during daytime, due to vehicular emissions from the road. We also determined the statistical correlations of the sequential time series of the particle number size distributions at the roadside site, and the traffic densities. The computed Pearson correlation coefficients for the downwind cases were substantially high for UFP's (>0.6, and low for accumulation mode particles; the latter is due to the substantial contribution of long-range transported particles in that size range. We also utilized this dataset for evaluating the performance of a modeling system that consists of a roadside dispersion model CAR-FMI (Contaminants in the Air from a Road – Finnish Meteorological Institute, a meteorological pre-processing model MPP-FMI and an aerosol process model UHMA (University of Helsinki Model for Aerosol processes. Model simulations underpredicted the particle number concentrations at the measurement site, which was caused by uncertainties in the emission modeling, especially in the UFP size range.

  18. Analysis of particle size distribution changes between three measurement sites in northern Scandinavia

    Science.gov (United States)

    Väänänen, R.; Kyrö, E.-M.; Nieminen, T.; Kivekäs, N.; Junninen, H.; Virkkula, A.; Dal Maso, M.; Lihavainen, H.; Viisanen, Y.; Svenningsson, B.; Holst, T.; Arneth, A.; Aalto, P. P.; Kulmala, M.; Kerminen, V.-M.

    2013-12-01

    We investigated atmospheric aerosol particle dynamics in a boreal forest zone in northern Scandinavia. We used aerosol number size distribution data measured with either a differential mobility particle sizer (DMPS) or scanning mobility particle sizer (SMPS) at three stations (Värriö, Pallas and Abisko), and combined these data with the HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) air mass trajectory analysis. We compared three approaches: analysis of new particle formation events, investigation of aerosol particle number size distributions during the air mass transport from the ocean to individual stations with different overland transport times, and analysis of changes in aerosol particle number size distributions during the air mass transport from one measurement station to another. Aitken-mode particles were found to have apparent average growth rates of 0.6-0.7 nm h-1 when the air masses traveled over land. Particle growth rates during the new particle formation (NPF) events were 3-6 times higher than the apparent particle growth during the summer period. When comparing aerosol dynamics for different overland transport times between the different stations, no major differences were found, except that in Abisko the NPF events were observed to take place in air masses with shorter overland times than at the other stations. We speculate that this is related to the meteorological differences along the paths of air masses caused by the land surface topology. When comparing air masses traveling in an east-to-west direction with those traveling in a west-to-east direction, clear differences in the aerosol dynamics were seen. Our results suggest that the condensation growth has an important role in aerosol dynamics even when NPF is not evident.

  19. Size-Segregated Multi-Elemental Aerosol Analysis at Williams Tower During Texas Air Quality 2000

    International Nuclear Information System (INIS)

    Size-segregated aerosol composition was investigated as part of the Texas 2000 air quality study. The sampling was performed continuously from August 16 to September 15, 2000 at the Williams Tower (62nd floor), Houston, Texas, using a Lundgren type 3-stage impactor (0.07-0.34 microns, 0.34-1.15 microns, and 1.15-2.5 microns cut points). Ex post facto analysis of the collected aerosol was performed using synchrotron x-ray fluorescence (s-XRF) at the Advanced Light Source (ALS) Lawrence Berkeley National Laboratory (LBNL) to yield time series data for many trace elements (Al, Si, S, Ca, Fe, Cl, K, Ti, Mn, Ni, and Cu). A principle component analysis of the data enabled the aerosol to be grouped into three primary types: (1) course mode soil and/or fly ash aerosol (Al, Si, S, Ca, Fe, K, Ti); (2) medium mode soil and/or fly ash aerosol (Al, Si, Ca, Fe, Ti); and (3) sulfur-containing aerosol containing a vanadium-to-nickel ratio of 3.231.35 (2 sigmas). An examination of time series data of element ratios has indicated that the first two aerosol types (Al:Si, Fe:Si, and Ca:Si ratios) may arise from multiple sources, whereas the latter aerosol type (V:S and Ni:S ratios) likely arises from a single source, such as fossil fuel combustion. The three aerosol types above were observed to have mass contributions, respectively, of 18.5%, 14.1%, and 65.8%. The statistical grouping of aerosol type is analyzed further according to air-mass history using classical back-trajectories and enables a source apportionment of the aerosol to be made

  20. SIZE DISTRIBUTION AND RATE OF PRODUCTION OF AIRBORNE PARTICULATE MATTER GENERATED DURING METAL CUTTING

    International Nuclear Information System (INIS)

    During deactivation and decommissioning activities, thermal cutting tools, such as plasma torch, laser, and gasoline torch, are used to cut metals. These activities generate fumes, smoke and particulates. These airborne species of matter, called aerosols, may be inhaled if suitable respiratory protection is not used. Inhalation of the airborne metallic aerosols has been reported to cause ill health effects, such as acute respiratory syndrome and chromosome damage in lymphocytes. In the nuclear industry, metals may be contaminated with radioactive materials. Cutting these metals, as in size reduction of gloveboxes and tanks, produces high concentrations of airborne transuranic particles. Particles of the respirable size range (size < 10 microm) deposit in various compartments of the respiratory tract, the fraction and the site in the respiratory tract depending on the size of the particles. The dose delivered to the respiratory tract depends on the size distribution of the airborne particulates (aerosols) and their concentration and radioactivity/toxicity. The concentration of airborne particulate matter in an environment is dependent upon the rate of their production and the ventilation rate. Thus, measuring aerosol size distribution and generation rate is important for (1) the assessment of inhalation exposures of workers, (2) the selection of respiratory protection equipment, and (3) the design of appropriate filtration systems. Size distribution of the aerosols generated during cutting of different metals by plasma torch was measured. Cutting rates of different metals, rate of generation of respirable mass, as well as the fraction of the released kerf that become respirable were determined. This report presents results of these studies. Measurements of the particles generated during cutting of metal plates with a plasma arc torch revealed the presence of particles with mass median aerodynamic diameters of particles close to 0.2 micro

  1. Size-resolved aerosol chemistry on Whistler Mountain, Canada with a high-resolution aerosol mass spectrometer during INTEX-B

    OpenAIRE

    Sun, Y.; Q. Zhang; Macdonald, A. M.; Hayden, K.; Li, S. M.; Liggio, J.; P. S. K. Liu; K. G. Anlauf; Leaitch, W. R.; Steffen, A.; Cubison, M.; Worsnop, D. R.; Van Donkelaar, A; R. V. Martin

    2009-01-01

    An Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed at the peak of Whistler Mountain (2182 m above sea level), British Columbia, from 19 April to 16 May 2006, as part of the Intercontinental Chemical Transport Experiment Phase B (INTEX-B) campaign. The mass concentrations and size distributions of non-refractory submicron particle (NR-PM1) species (i.e., sulfate, nitrate, ammonium, chloride, and organics) were measured in situ at 10...

  2. Aerosols, clouds, and precipitation in the North Atlantic trades observed during the Barbados aerosol cloud experiment - Part 1: Distributions and variability

    Science.gov (United States)

    Jung, Eunsil; Albrecht, Bruce A.; Feingold, Graham; Jonsson, Haflidi H.; Chuang, Patrick; Donaher, Shaunna L.

    2016-07-01

    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 clouds were less than 1 km

  3. Reconciliation of coarse mode sea-salt aerosol particle size measurements and parameterizations at a subtropical ocean receptor site

    Science.gov (United States)

    Reid, Jeffrey S.; Brooks, Barbara; Crahan, Katie K.; Hegg, Dean A.; Eck, Thomas F.; O'Neill, Norm; de Leeuw, Gerrit; Reid, Elizabeth A.; Anderson, Kenneth D.

    2006-01-01

    In August/September of 2001, the R/P FLIP and CIRPAS Twin Otter research aircraft were deployed to the eastern coast of Oahu, Hawaii, as part of the Rough Evaporation Duct (RED) experiment. Goals included the study of the air/sea exchange, turbulence, and sea-salt aerosol particle characteristics at the subtropical marine Pacific site. Here we examine coarse mode particle size distributions. Similar to what has been shown for airborne dust, optical particle counters such as the Forward Scattering Spectrometer Probe (FSSP), Classical Scattering Aerosol Spectrometer Probe (CSASP) and the Cloud Aerosol Spectrometer (CAS) within the Cloud Aerosol and Precipitation Spectrometer (CAPS) instrument systematically overestimate particle size, and consequently volume, for sea salt particles. Ground-based aerodynamic particle sizers (APS) and AERONET inversions yield much more reasonable results. A wing pod mounted APS gave mixed results and may not be appropriate for marine boundary layer studies. Relating our findings to previous studies does much to explain the bulk of the differences in the literature and leads us to conclude that the largest uncertainty facing flux and airborne cloud/aerosol interaction studies is likely due to the instrumentation itself. To our knowledge, there does not exist an in situ aircraft system that adequately measures the ambient volume distribution of coarse mode sea salt particles. Most empirically based sea salt flux parameterizations can trace their heritage to a clearly biased measurement technique. The current "state of the art" in this field prevents any true form of clear sky radiative "closure" for clean marine environments.

  4. Particle concentrations and number size distributions in the planetary boundary layer derived from airship based measurements

    Science.gov (United States)

    Tillmann, Ralf; Zhao, Defeng; Ehn, Mikael; Hofzumahaus, Andreas; Holland, Frank; Rohrer, Franz; Kiendler-Scharr, Astrid; Wahner, Andreas

    2014-05-01

    Atmospheric particles play a key role for regional and global climate due to their direct and indirect radiative forcing effects. The concentration and size of the particles are important variables to these effects. Within the continental planetary boundary layer (PBL) the particle number size distribution is influenced by meteorological parameters, local sinks and sources resulting in variable spatial distributions. However, measurements of particle number size distributions over a broad vertical range of the PBL are rare. The airship ZEPPELIN NT is an ideal platform to measure atmospheric aerosols on a regional scale within an altitude range up to 1000 m. For campaigns in the Netherlands, Northern Italy and South Finland in 2012 and 2013 the airship was deployed with a wide range of instruments, including measurements of different trace gases, short lived radicals, solar radiation, aerosols and meteorological parameters. Flights were carried out at different times of the day to investigate the influence of the diurnal evolution of the PBL on atmospheric trace gases and aerosols. During night and early morning hours the concentration and size distribution of atmospheric particles were found to be strongly influenced by the layered structure of the PBL, i.e. the nocturnal boundary layer and the residual layer. Within the residual layer particle concentrations stay relatively constant as this layer is decoupled from ground sources. The particles persist in the accumulation mode as expected for an aged aerosol. In the nocturnal boundary layer particle concentrations and size are more dynamic with higher concentrations than in the residual layer. A few hours after sunrise, the layered structure of the PBL intermixes. During daytime the PBL is well mixed and a negative concentration gradient with increasing height is observed. Several height profiles at different times of the day and at different locations in Europe were measured. The aerosol measurements will be

  5. Distribution and clearance of radioactive aerosol on the nasal mucosa.

    Science.gov (United States)

    McLean, J A; Bacon, J R; Mathews, K P; Thrall, J H; Banas, J M; Hedden, J; Bayne, N K

    1984-03-01

    The distribution and clearance of aerosolized radioactive technetium 99m pertechnate in physiologic buffered saline was analyzed in four human adult asymptomatic volunteers following delivery into one nostril in the same manner as for nasal challenge testing (i.e., 0.1 ml via a 251 DeVilbiss atomizer powered by a compressor delivering 0.10 +/- 0.01 gm/spray). For comparison, squeeze bottles and spray bottles from commercial sources, a 114 and a 127 DeVilbiss atomizer, and a pipette were employed. Lateral imagery via minicomputer processing was used to determine both distribution and clearance of the radiotracer. The counts after 1 minute were lower following pipette delivery than with the other devices. None yielded discernable , wide-spread distribution of aerosol throughout the nasal cavity. Following delivery from the 251 atomizer, mean clearance at 17 minutes was 60.0%. Similar clearance rates were obtained with the other spraying methods except for lower values with the squeeze bottle. Analysis of six hour clearance studies by linear regression showed a relatively rapid initial phase, which is probably due largely to mucociliary clearance, and a prolonged late phase related to the very slow disappearance of residual material located far anteriorly in the nose. Achieving good initial retention and rapid clearance of material deposited anteriorly in the nose are desirable attributes of devices employed for administering materials intranasally. PMID:6328631

  6. Bimodal Distribution of Sulfuric Acid Aerosols in the Upper Haze of Venus

    CERN Document Server

    Gao, Peter; Crisp, David; Bardeen, Charles G; Yung, Yuk L

    2013-01-01

    The upper haze (UH) of Venus is variable on the order of days and it is populated by two particle modes. We use a 1D microphysics and vertical transport model based on the Community Aerosol and Radiation Model for Atmospheres to evaluate whether interaction of upwelled cloud particles and sulfuric acid particles nucleated in situ on meteoric dust are able to generate the two size modes and whether their observed variability are due to cloud top vertical transient winds. Nucleation of photochemically produced sulfuric acid onto polysulfur condensation nuclei generates mode 1 cloud droplets that then diffuse upwards into the UH. Droplets generated in the UH from nucleation of sulfuric acid onto meteoric dust coagulate with the upwelled cloud particles and cannot reproduce the observed bimodal size distribution. The mass transport enabled by cloud top transient winds are able to generate a bimodal size distribution in a time scale consistent with observations. Sedimentation and convection in the middle and lower...

  7. Evaluation of a global aerosol microphysics model against size-resolved particle statistics in the marine atmosphere

    Directory of Open Access Journals (Sweden)

    D. V. Spracklen

    2007-01-01

    Full Text Available A statistical synthesis of marine aerosol measurements from experiments in four different oceans is used to evaluate a global aerosol microphysics model (GLOMAP. We compare the model against observed size resolved particle concentrations, probability distributions, and the temporal persistence of different size particles. We attempt to explain the observed sub-micrometre size distributions in terms of sulfate and sea spray and quantify the possible contributions of anthropogenic sulfate and carbonaceous material to the number and mass distribution. The model predicts a bimodal size distribution that agrees well with observations as a grand average over all regions, but there are large regional differences. Notably, observed Aitken mode number concentrations are more than a factor 10 higher than in the model for the N Atlantic but a factor 7 lower than the model in the NW Pacific. We also find that modelled Aitken mode and accumulation mode geometric mean diameters are generally smaller in the model by 10–30%. Comparison with observed free tropospheric Aitken mode distributions suggests that the model underpredicts growth of these particles during descent to the marine boundary layer (MBL. Recent observations of a substantial organic component of free tropospheric aerosol could explain this discrepancy. We find that anthropogenic continental material makes a substantial contribution to N Atlantic MBL aerosol, with typically 60–90% of sulfate across the particle size range coming from anthropogenic sources, even if we analyse air that has spent an average of >120 h away from land. However, anthropogenic primary black carbon and organic carbon particles (at the emission size and quantity assumed here do not explain the large discrepancies in Aitken mode number. Several explanations for the discrepancy are suggested. The lack of lower atmospheric particle formation in the model may explain low N Atlantic particle concentrations. However, the

  8. 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

  9. Physical Causes of Drop Size Distribution Variability

    Science.gov (United States)

    Zawadzki, I.

    Drop size distributions are measured at ground by instruments (disdrometers) that mostly sample one drop at a time or at best, a small number of drops simultaneously. To obtain a representative sample a time window of the observations is required. This introduces a spurious variability due to the differential fall speed of drops coupled with a highly variable field of precipitation in rapid displacement respect to the dis- drometer. A filter has been studied to minimize this spurious variability as well as instrumental uncertainty. The use of filtered data allows to see case to case differences in DSDs that are hidden in the large scatter in the raw data. These differences can be associated to physical processes revealed by a vertically pointing radar such as the de- gree of aggregation, riming, etc. Numerical modeling of particle size evolution using the quasi-stochastic growth equation serves as guide for the understanding of these processes.

  10. Size and compositional analyses of biologically active aerosols from a CO2 and diode laser plume

    International Nuclear Information System (INIS)

    Modern medical procedures, including laser surgery, can generate fine aerosols that may carry biologically active agents. With such procedures becoming more commonplace, it is evident that we need to look at the health implications on hospital staff when dealing with highly contagious patients with bacterial and/or viral infections, such as AIDS. The focus of this study is not to determine what portion that population is actually harmful, only to deduce what segment is still biologically active after vaporization from tissues. We have developed procedures to collect and analyze aerosols by size (from >10 μm to less than 0.07 μm) and by time (from minutes to ∼4 hour increments). Health relevant size cuts for aerosols in a work environment have been adopted by the International Organization for Standardization and the Comite of European de Normalisation. We examined both the nature of the aerosols generated and the efficiency of hospital masks used by personnel in screening aerosols and simulated conditions under which aerosols might be inhaled. Four sets of data were recorded: Mask filtered physical, mask filtered biological, unfiltered physical and unfiltered biological. A combination of PIXE analyses on impactor and filter samples were matched with filters and strips plated on agarose plates and counted for colony forming units to determine the biologically active subset of the population. (author)

  11. PIXE–PIGE analysis of size-segregated aerosol samples from remote areas

    International Nuclear Information System (INIS)

    The chemical characterization of size-segregated samples is helpful to study the aerosol effects on both human health and environment. The sampling with multi-stage cascade impactors (e.g., Small Deposit area Impactor, SDI) produces inhomogeneous samples, with a multi-spot geometry and a non-negligible particle stratification. At LABEC (Laboratory of nuclear techniques for the Environment and the Cultural Heritage), an external beam line is fully dedicated to PIXE–PIGE analysis of aerosol samples. PIGE is routinely used as a sidekick of PIXE to correct the underestimation of PIXE in quantifying the concentration of the lightest detectable elements, like Na or Al, due to X-ray absorption inside the individual aerosol particles. In this work PIGE has been used to study proper attenuation correction factors for SDI samples: relevant attenuation effects have been observed also for stages collecting smaller particles, and consequent implications on the retrieved aerosol modal structure have been evidenced

  12. Development and validation of a size-resolved particle dry deposition scheme for applications in aerosol transport models

    Directory of Open Access Journals (Sweden)

    A. Petroff

    2010-08-01

    Full Text Available A size-resolved particle dry deposition scheme is developed, which has been designed for inclusion in large-scale air quality and climate models, where the size distribution and fate of the atmospheric aerosol is of concern. The "resistance" structure is similar to what is proposed by Zhang et al. (2001, 2003, while a new "surface" deposition velocity (or surface resistance is derived by simplification of a one-dimensional aerosol transport model (Petroff et al., 2008b, 2009. Collection efficiencies are given for the 26 Land Use Categories that decribe the earth surface. Validation of this model with existing measurements is performed on desert, grass, coniferous forest and liquid water surfaces. A comparison of this model with measurements on snow and ice is also given. Even though a qualitative agreement is reached, further size-segegated measurements are needed in order to confirm the model accuracy on this surface. The present analytical model provides more accurate predictions of the aerosol deposition on these surfaces than previous models.

  13. Aerosol particle size does not predict pharmacokinetic determined lung dose in children

    DEFF Research Database (Denmark)

    Bønnelykke, Klaus; Chawes, Bo L K; Vindfeld, Signe;

    2013-01-01

    In vitro measures of aerosol particles size, such as the fine particle mass, play a pivotal role for approval of inhaled anti-asthmatic drugs. However, the validity as a measure of dose to the lungs in children lacks evidence. In this study we investigated for the first time the association between...... was assessed after single inhalation. The corresponding emitted mass of drug in segments of aerosol particle size was assessed ex vivo by replicating the inhalation flows recorded by transducers built into the Diskus® inhaler and re-playing them in a breathing simulator. There was no correlation between any...... of drug delivery to the lung....

  14. A concept of an automated function control for ambient aerosol measurements using mobility particle size spectrometers

    Science.gov (United States)

    Bastian, S.; Löschau, G.; Wiedensohler, A.

    2014-04-01

    An automated function control unit was developed to regularly check the ambient particle number concentration derived from a mobility particle size spectrometer as well as its zero-point behaviour. The function control allows unattended quality assurance experiments at remote air quality monitoring or research stations under field conditions. The automated function control also has the advantage of being able to get a faster system stability response than the recommended on-site comparisons with reference instruments. The method is based on a comparison of the total particle number concentration measured by a mobility particle size spectrometer and a condensation particle counter while removing diffusive particles smaller than 20 nm in diameter. In practice, the small particles are removed by a set of diffusion screens, as traditionally used in a diffusion battery. Another feature of the automated function control is to check the zero-point behaviour of the ambient aerosol passing through a high-efficiency particulate air (HEPA) filter. The performance of the function control is illustrated with the aid of a 1-year data set recorded at Annaberg-Buchholz, a station in the Saxon air quality monitoring network. During the period of concern, the total particle number concentration derived from the mobility particle size spectrometer slightly overestimated the particle number concentration recorded by the condensation particle counter by 2 % (grand average). Based on our first year of experience with the function control, we developed tolerance criteria that allow a performance evaluation of a tested mobility particle size spectrometer with respect to the total particle number concentration. We conclude that the automated function control enhances the quality and reliability of unattended long-term particle number size distribution measurements. This will have beneficial effects for intercomparison studies involving different measurement sites, and help provide a higher

  15. Spatial distributions and seasonal cycles of aerosol climate effects in India seen in global climate-aerosol model

    Directory of Open Access Journals (Sweden)

    S. V. Henriksson

    2013-07-01

    Full Text Available Climate-aerosol interactions in India are studied by employing the global climate-aerosol model ECHAM5-HAM and the GAINS inventory for anthropogenic aerosol emissions. Seasonal cycles and spatial distributions of radiative forcing and the temperature and rainfall responses are presented for different model setups. While total aerosol radiative forcing is strongest in the summer, anthropogenic forcing is considerably stronger in winter than in summer. Local seasonal temperature anomalies caused by aerosols are mostly negative with some exceptions, e.g. Northern India in March–May and the eastern Himalayas in September–November. Rainfall increases due to the elevated heat pump (EHP mechanism and decreases due to solar dimming effects are studied. Aerosol light absorption does increase rainfall significantly in Northern India, but effects due to solar dimming and circulation work to cancel the increase. The total aerosol effect on rainfall is negative when considering all effects if assuming that aerosols have cooled the Northern Indian Ocean by 0.5 °K compared to the equator.

  16. A sea-state based source function for size- and composition-resolved marine aerosol production

    Directory of Open Access Journals (Sweden)

    M. S. Long

    2010-09-01

    Full Text Available A parameterization for the size- and composition-resolved production fluxes of nascent marine aerosol was developed from prior experimental observations and extrapolated to ambient conditions based on estimates of air entrainment by the breaking of wind-driven ocean waves. Production of particulate organic carbon (OCaer was parameterized based on Langmuir equilibrium-type association of organic matter to bubble plumes in seawater and resulting aerosol as constrained by measurements of aerosol produced from productive and oligotrophic seawater. This novel approach is the first to parameterize size- and composition-resolved aerosol production based on explicit evaluation of wind-driven air entrainment/detrainment fluxes and chlorophyll-a as a proxy for surfactants in surface seawater. Production fluxes were simulated globally with an eight aerosol-size-bin version of the NCAR Community Atmosphere Model (CAM v3.5.07. Simulated production fluxes fell within the range of published estimates based on observationally constrained parameterizations. Because the parameterization does not consider contributions from spume drops, the simulated global mass flux (1.5×103 Tg y−1 is near the lower end of published estimates. The simulated production of aerosol number (1.4×106 cm−2 s−1 and OCaer (29 Tg C y−1 fall near the upper end of published estimates and suggest that primary marine aerosols may have greater influences on the physicochemical evolution of the troposphere, radiative transfer and climate, and associated feedbacks on the surface ocean than suggested by previous model studies.

  17. Particle Morphology and Size Results from the Smoke Aerosol Measurement Experiment-2

    Science.gov (United States)

    Urban, David L.; Ruff, Gary A.; Greenberg, Paul S.; Fischer, David; Meyer, Marit; Mulholland, George; Yuan, Zeng-Guang; Bryg, Victoria; Cleary, Thomas; Yang, Jiann

    2012-01-01

    Results are presented from the Reflight of the Smoke Aerosol Measurement Experiment (SAME-2) which was conducted during Expedition 24 (July-September 2010). The reflight experiment built upon the results of the original flight during Expedition 15 by adding diagnostic measurements and expanding the test matrix. Five different materials representative of those found in spacecraft (Teflon, Kapton, cotton, silicone rubber and Pyrell) were heated to temperatures below the ignition point with conditions controlled to provide repeatable sample surface temperatures and air flow. The air flow past the sample during the heating period ranged from quiescent to 8 cm/s. The smoke was initially collected in an aging chamber to simulate the transport time from the smoke source to the detector. This effective transport time was varied by holding the smoke in the aging chamber for times ranging from 11 to 1800 s. Smoke particle samples were collected on Transmission Electron Microscope (TEM) grids for post-flight analysis. The TEM grids were analyzed to observe the particle morphology and size parameters. The diagnostics included a prototype two-moment smoke detector and three different measures of moments of the particle size distribution. These moment diagnostics were used to determine the particle number concentration (zeroth moment), the diameter concentration (first moment), and the mass concentration (third moment). These statistics were combined to determine the diameter of average mass and the count mean diameter and, by assuming a log-normal distribution, the geometric mean diameter and the geometric standard deviations can also be calculated. Overall the majority of the average smoke particle sizes were found to be in the 200 nm to 400 nm range with the quiescent cases producing some cases with substantially larger particles.

  18. Chamber bioaerosol study: human emissions of size-resolved fluorescent biological aerosol particles.

    Science.gov (United States)

    Bhangar, S; Adams, R I; Pasut, W; Huffman, J A; Arens, E A; Taylor, J W; Bruns, T D; Nazaroff, W W

    2016-04-01

    Humans are a prominent source of airborne biological particles in occupied indoor spaces, but few studies have quantified human bioaerosol emissions. The chamber investigation reported here employs a fluorescence-based technique to evaluate bioaerosols with high temporal and particle size resolution. In a 75-m(3) chamber, occupant emission rates of coarse (2.5-10 μm) fluorescent biological aerosol particles (FBAPs) under seated, simulated office-work conditions averaged 0.9 ± 0.3 million particles per person-h. Walking was associated with a 5-6× increase in the emission rate. During both walking and sitting, 60-70% or more of emissions originated from the floor. The increase in emissions during walking (vs. while sitting) was mainly attributable to release of particles from the floor; the associated increased vigor of upper body movements also contributed. Clothing, or its frictional interaction with human skin, was demonstrated to be a source of coarse particles, and especially of the highly fluorescent fraction. Emission rates of FBAPs previously reported for lecture classes were well bounded by the experimental results obtained in this chamber study. In both settings, the size distribution of occupant FBAP emissions had a dominant mode in the 3-5 μm diameter range. PMID:25704637

  19. Unattached fraction and the size distribution of the radon progeny in indoor air

    International Nuclear Information System (INIS)

    The size-distribution of the aerosol-attached radon progeny and the unattached (cluster) fraction were measured by using a low pressure cascade impactor and a single wire screen in a building of the nuclear facility. The radon concentration at the condition of ventilation 'ON' was about 50 Bq m-3, but it increased exponentially after ventilation 'OFF' and reached to the saturated concentration of about 600 Bq m-3. At the condition of low aerosol concentration without additional aerosol, the activity median aerodynamic diameter, the geometric standard deviation and the unattached fraction were, respectively, 0.4 μm, 2.7-2.9 and 0.3-0.5. On the other hand, at the condition of high aerosol concentration with burning a mosquito coil, these were, 0.4 μm, 2.1 and 0.02-0.03. These yield 2.5 times higher radiation dose conversion factors at the low aerosol condition than the high aerosol condition. (author)

  20. The global 3-D distribution of tropospheric aerosols as characterized by CALIOP

    Directory of Open Access Journals (Sweden)

    D. M. Winker

    2013-03-01

    Full Text Available The CALIOP lidar, carried on the CALIPSO satellite, has been acquiring global atmospheric profiles since June 2006. This dataset now offers the opportunity to characterize the global 3-D distribution of aerosol as well as seasonal and interannual variations, and confront aerosol models with observations in a way that has not been possible before. With that goal in mind, a monthly global gridded dataset of daytime and nighttime aerosol extinction profiles has been constructed, available as a Level 3 aerosol product. Averaged aerosol profiles for cloud-free and all-sky conditions are reported separately. This 6-yr dataset characterizes the global 3-dimensional distribution of tropospheric aerosol. Vertical distributions are seen to vary with season, as both source strengths and transport mechanisms vary. In most regions, clear-sky and all-sky mean aerosol profiles are found to be quite similar, implying a lack of correlation between high semi-transparent cloud and aerosol in the lower troposphere. An initial evaluation of the accuracy of the aerosol extinction profiles is presented. Detection limitations and the representivity of aerosol profiles in the upper troposphere are of particular concern. While results are preliminary, we present evidence that the monthly-mean CALIOP aerosol profiles provide quantitative characterization of elevated aerosol layers in major transport pathways. Aerosol extinction in the free troposphere in clean conditions, where the true aerosol extinction is typically 0.001 km−1 or less, is generally underestimated, however. The work described here forms an initial global 3-D aerosol climatology which we plan to extend and improve over time.

  1. Particle Size of Aerosols Produced in Different Operations on Plutonium Solutions

    International Nuclear Information System (INIS)

    The transfer of a plutonium solution from one container to another gives rise to risks of aerosol production if a drop of the solution falls from a certain height on to a hard surface, and when the film of solution remaining on uncovered surfaces evaporates. A systematic study of these phenomena was undertaken to determine the rate of production of aerosols, their size and the efficiency of industrial filters. Using solutions of different concentrations, the authors performed transfers, dropping experiments and evaporations. The first results on particle size and filter efficiency were obtained by autoradiography on nuclear plates. They show that the aerosols are very small and that in this case the penetration rate for some filters is relatively high. (author)

  2. Size-Limited Penetration of Nanoparticles into Porcine Respiratory Mucus after Aerosol Deposition.

    Science.gov (United States)

    Murgia, Xabier; Pawelzyk, Paul; Schaefer, Ulrich F; Wagner, Christian; Willenbacher, Norbert; Lehr, Claus-Michael

    2016-04-11

    We investigated the rheological properties and the penetration of differently sized carboxylated nanoparticles in pig pulmonary mucus, on different distance and time scales. Nanoparticles were either mechanically mixed into the mucus samples or deposited as an aerosol, the latter resembling a more physiologically relevant delivery scenario. After mechanical dispersion, 500 nm particles were locally trapped; a fraction of carboxylated tracer particles of 100 or 200 nm in diameter could however freely diffuse in these networks over distances of approximately 20 μm. In contrast, after aerosol deposition on top of the mucus layer only particles with a size of 100 nm were able to penetrate into mucus, suggesting the presence of smaller pores at the air-mucus interface compared to within mucus. These findings are relevant to an understanding of the fate of potentially harmful aerosol particles, such as pathogens, pollutants, and other nanomaterials after incidental inhalation, as well as for the design of pulmonary drug delivery systems. PMID:26957140

  3. Chemical composition of size-segregated aerosols in Lhasa city, Tibetan Plateau

    Science.gov (United States)

    Wan, Xin; Kang, Shichang; Xin, Jinyuan; Liu, Bin; Wen, Tianxue; Wang, Pengling; Wang, Yuesi; Cong, Zhiyuan

    2016-06-01

    To reveal the chemical characteristics of size-segregated aerosols in the high-altitude city of Tibetan Plateau, eight-size aerosol samples were collected in Lhasa from March 2013 to February 2014. The annual mean of online PM2.5 was 25.0 ± 16.0 μg m- 3, which was much lower than Asian cities but similar with some European cities. The annual mean concentrations of organic carbon (OC, 7.92 μg m- 3 in PM2.1 and 12.66 μg m- 3 in PM9.0) and elemental carbon (EC, 1.00 μg m- 3 in PM2.1 and 1.21 μg m- 3 in PM9.0) in Lhasa aerosols were considerably lower than those heavily polluted cities such as Beijing and Xi'an, China and Kathmandu, Nepal. Sulfate, NO3-, NH4+ and Ca2 + were 0.75 ± 0.31, 0.82 ± 0.35, 0.38 ± 0.34 and 0.57 ± 0.29 μg m- 3 in fine particles while in coarse particles they were 0.57 ± 0.37, 0.73 ± 0.23, 0.07 ± 0.03 and 2.52 ± 1.37 μg m- 3, respectively. Secondary water-soluble ions composed 35.8% of the total ionic components in fine particles according to the established electroneutrality, while in coarse particles they took up only 9.3%. Ca2 + (40.6%) was the major component of the coarse particles. For seasonality, the concentrations of OC, EC, SO42 -, NH4+, K+, Ca2 +, Mg2 +, Cl- and Na+ presented higher values during late autumn and winter but were relatively lower in spring and summer. Nevertheless, NO3- was considerably higher in summer and autumn, presumably due to increased tourist-vehicle emissions. During winter and spring, [Ca2 +]/[NO3-+ SO42 -] ratios in coarse particles showed higher values of 7.31 and 6.17, respectively, emphasizing the dust influence. [NO3-]/[SO42 -] ratios in fine particles during spring, summer and autumn exceeding 1 indicated that the currently predominant vehicle exhaust makes a greater contribution to the aerosols. While more stationary sources such as coal and biomass burning existed in winter since the [NO3-]/[SO42 -] ratio was less than 1. Different sources and formation processes lead to a bimodal size

  4. Sensitivity of remote aerosol distributions to representation of cloud-aerosol interactions in a global climate model

    Directory of Open Access Journals (Sweden)

    H. Wang

    2013-01-01

    increase in the Arctic winter (summer BC burden. This BC aging treatment, however, has minimal effect on other under-predicted species. Interestingly, our modifications to CAM5 that aim at improving prediction of high-latitude and upper tropospheric aerosols also produce much better aerosol optical depth over various other regions globally when compared to multi-year AERONET retrievals. The improved aerosol distributions have impacts on other aspects of CAM5, improving the simulation of global mean liquid water path and cloud forcing.

  5. Statistical inference and crystallite size distributions

    International Nuclear Information System (INIS)

    An information theory approach is devised in order to obtain crystallite size distributions from X-ray line broadening. The method is shown to be superior to those based on Fourier expansions, as illustrated by numerical examples and a realistic situation. The powder model of Warren and Averbach is considered, in which the sample is thought of as a 'column-like' structure of unit cells perpendicular to the diffraction plane. Errors in excess of 100% arise as a result of truncating the diffraction peak. It is shown that, with the present approach, the corresponding figure is reduced to 5%, which confirms the power of information theory, and makes this method especially convenient in those cases in which there are large overlaps between the tails of two diffraction peaks. (orig.)

  6. Statistical inference and crystallite size distributions

    Energy Technology Data Exchange (ETDEWEB)

    Guerin, D.M.A.; Alvarez, A.G.; Rebollo Neira, L.E.; Plastino, A.; Bonetto, R.D.

    1986-01-01

    An information theory approach is devised in order to obtain crystallite size distributions from X-ray line broadening. The method is shown to be superior to those based on Fourier expansions, as illustrated by numerical examples and a realistic situation. The powder model of Warren and Averbach is considered, in which the sample is thought of as a 'column-like' structure of unit cells perpendicular to the diffraction plane. Errors in excess of 100% arise as a result of truncating the diffraction peak. It is shown that, with the present approach, the corresponding figure is reduced to 5%, which confirms the power of information theory, and makes this method especially convenient in those cases in which there are large overlaps between the tails of two diffraction peaks. (orig.).

  7. Fisher Information in Flow Size Distribution

    CERN Document Server

    Tune, Paul

    2011-01-01

    The flow size distribution is a useful metric for traffic modeling and management. Its estimation based on sampled data, however, is problematic. Previous work has shown that flow sampling (FS) offers enormous statistical benefits over packet sampling but high resource requirements precludes its use in routers. We present Dual Sampling (DS), a two-parameter family, which, to a large extent, provide FS-like statistical performance by approaching FS continuously, with just packet-sampling-like computational cost. Our work utilizes a Fisher information based approach recently used to evaluate a number of sampling schemes, excluding FS, for TCP flows. We revise and extend the approach to make rigorous and fair comparisons between FS, DS and others. We show how DS significantly outperforms other packet based methods, including Sample and Hold, the closest packet sampling-based competitor to FS. We describe a packet sampling-based implementation of DS and analyze its key computational costs to show that router impl...

  8. Development and validation of a size-resolved particle dry deposition scheme for application in aerosol transport models

    Directory of Open Access Journals (Sweden)

    A. Petroff

    2010-12-01

    Full Text Available A size-resolved particle dry deposition scheme is developed for inclusion in large-scale air quality and climate models where the size distribution and fate of atmospheric aerosols is of concern. The "resistance" structure is similar to what is proposed by Zhang et al. (2001, while a new "surface" deposition velocity (or surface resistance is derived by simplification of a one-dimensional aerosol transport model (Petroff et al., 2008b, 2009. Compared to Zhang et al.'s model, the present model accounts for the leaf size, shape and area index as well as the height of the vegetation canopy. Consequently, it is more sensitive to the change of land covers, particularly in the accumulation mode (0.1–1 micron. A drift velocity is included to account for the phoretic effects related to temperature and humidity gradients close to liquid and solid water surfaces. An extended comparison of this model with experimental evidence is performed over typical land covers such as bare ground, grass, coniferous forest, liquid and solid water surfaces and highlights its adequate prediction. The predictions of the present model differ from Zhang et al.'s model in the fine mode, where the latter tends to over-estimate in a significant way the particle deposition, as measured by various investigators or predicted by the present model. The present development is thought to be useful to modellers of the atmospheric aerosol who need an adequate parameterization of aerosol dry removal to the earth surface, described here by 26 land covers. An open source code is available in Fortran90.

  9. Development and validation of a size-resolved particle dry deposition scheme for application in aerosol transport models

    Science.gov (United States)

    Petroff, A.; Zhang, L.

    2010-12-01

    A size-resolved particle dry deposition scheme is developed for inclusion in large-scale air quality and climate models where the size distribution and fate of atmospheric aerosols is of concern. The "resistance" structure is similar to what is proposed by Zhang et al. (2001), while a new "surface" deposition velocity (or surface resistance) is derived by simplification of a one-dimensional aerosol transport model (Petroff et al., 2008b, 2009). Compared to Zhang et al.'s model, the present model accounts for the leaf size, shape and area index as well as the height of the vegetation canopy. Consequently, it is more sensitive to the change of land covers, particularly in the accumulation mode (0.1-1 micron). A drift velocity is included to account for the phoretic effects related to temperature and humidity gradients close to liquid and solid water surfaces. An extended comparison of this model with experimental evidence is performed over typical land covers such as bare ground, grass, coniferous forest, liquid and solid water surfaces and highlights its adequate prediction. The predictions of the present model differ from Zhang et al.'s model in the fine mode, where the latter tends to over-estimate in a significant way the particle deposition, as measured by various investigators or predicted by the present model. The present development is thought to be useful to modellers of the atmospheric aerosol who need an adequate parameterization of aerosol dry removal to the earth surface, described here by 26 land covers. An open source code is available in Fortran90.

  10. Refinement of size distributions for primary crystallizations

    International Nuclear Information System (INIS)

    The microstructure developed in primary crystallizations is studied under realistic conditions. The primary crystallization of an amorphous alloy is modeled by considering the thermodynamics of a metastable phase transition and the kinetics of nucleation and crystal growth under isothermal annealing. A realistic growth rate, including an interface controlled growth at the beginning of the growth of each single grain and diffusion controlled growth process with soft impingement afterwards is considered. The reduction in the nucleation rate due to the compositional change in the remaining amorphous matrix is also taken into account. The microstructures developed during the transformation are obtained by using the Populational KJMA method, from the above thermodynamic and kinetic factors. Experimental data of transformed fraction, grain density, average grain size, grain size distribution and other related parameters obtained from annealed metallic glasses are modeled. The authors will focus on the nanocrystallization of a FINEMET alloy. In particular, they will analyze the isothermal nanocrystalline precipitation of an α-Fe(Si) phase, with a DO3 defective in Si superstructure, in a FINEMET material of composition Fe73.5Si17.5Cu1Nb3B5

  11. On the competition among aerosol number, size and composition in predicting CCN variability: a multi-annual field study in an urbanized desert

    Directory of Open Access Journals (Sweden)

    E. Crosbie

    2015-02-01

    Full Text Available A two-year dataset of measured CCN concentrations at 0.2% supersaturation is combined with aerosol size distribution and aerosol chemistry data to probe the effects of aerosol number concentrations, size distribution and composition on CCN patterns. Data have been collected over a period of two years (2012–2014 in central Tucson, Arizona: a significant urban area surrounded by a sparsely populated desert. Average CCN concentrations are typically lowest in spring (233 cm−3, highest in winter (430 cm−3 and have a secondary peak during the North American Monsoon season (July to September; 372 cm−3. There is significant variability outside of seasonal patterns with extreme concentrations (1 and 99% levels ranging from 56 to 1945 cm−3 as measured during the winter, the season with highest variability. Modeled CCN concentrations based on fixed chemical composition achieve better closure in winter, with size and number alone able to predict 82% of the variance in CCN concentration. Changes in aerosol chemistry are typically aligned with changes in size and aerosol number, such that composition can be parameterized even though it is still variable. In summer, models based on fixed chemical composition explain at best only 41% (pre-monsoon and 36% (monsoon of the variance. This is attributed to the effects of secondary organic aerosol (SOA production, the competition between new particle formation and condensational growth, and the complex interaction of meteorology, regional and local emissions, and multi-phase chemistry during the North American Monsoon. Chemical composition is found to be an important factor for improving predictability in spring and on longer timescales in winter. Regimes where parameterized models exhibit improved predictive skill are typically explained by strong relationships between CCN concentrations and the prevailing meteorology and dominant aerosol chemistry mechanisms suggesting that similar findings could be

  12. Aggregate size distribution of the soil loss

    Science.gov (United States)

    Szabó, Judit Alexandra; Jakab, Gergely; Szabó, Boglárka; Józsa, Sándor; Szalai, Zoltán; Centeri, Csaba

    2016-04-01

    In agricultural areas the soil erosion and soil loss estimation is vital information in long-term planning. During the initial period of the erosion a part of the soil particles and aggregates get transportable and nutrients and organic matter could be transported due to the effect of water or wind. This preliminary phase was studied with laboratory-scale rainfall simulator. Developed surface crust and aggregate size composition of the runoff was examined in six different slope-roughness-moisture content combination of a Cambisol and a Regosol. The ratio of micro- and macro aggregates in the runoff indicate the stability of the aggregates and determine the transport capacity of the runoff. Both soil samples were taken from field where the water erosion is a potential hazard. During the experiment the whole amount of runoff and sediment was collected through sieve series to a bucket to separate the micro- and macro aggregates. In case of both samples the micro aggregates dominate in the runoff and the runoff rates are similar. Although the runoff of the Regosol - with dominant >1000μm macro aggregate content - contained almost nothing but ratio 250-1000μm sized macro aggregates. This difference occurred because the samples are resistant against drop erosion differently. In case of both sample the selectivity of the erosion and substance matrix redistribution manifested in mineral crusts in the surface where the quartz deposited in place while the lighter organic matter transported with the sediment. The detachment of the aggregates and the redistribution of the particles highly effect on the aggregate composition of the runoff which is connected with the quality of the soil loss. So while the estimation of soil loss quantity is more or less is easy, measuring aggregate size distribution which is led to nutrient and organic matter redistribution is one of a key questions to improve erosion estimation. G. Jakab was supported by the János Bolyai fellowship of the

  13. Size-Resolved Penetration Through High-Efficiency Filter Media Typically Used for Aerosol Sampling

    Czech Academy of Sciences Publication Activity Database

    Zíková, Naděžda; Ondráček, Jakub; Ždímal, Vladimír

    2015-01-01

    Roč. 49, č. 4 (2015), s. 239-249. ISSN 0278-6826 R&D Projects: GA ČR(CZ) GBP503/12/G147 Institutional support: RVO:67985858 Keywords : filters * size-resolved penetration * atmospheric aerosol sampling Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.413, year: 2014

  14. Reconciliation of coarse mode sea-salt aerosol particle size measurements and parameterizations at a subtropical ocean receptor site

    OpenAIRE

    Reid, J S; B. Brooks; Crahan, K. K.; De Leeuw, G.; E. A. Reid; Anderson, F.D.; D. A. Hegg; T. F. Eck; O'Neill, N.

    2006-01-01

    In August/September of 2001, the R/P FLIP and CIRPAS Twin Otter research aircraft were deployed to the eastern coast of Oahu, Hawaii, as part of the Rough Evaporation Duct (RED) experiment. Goals included the study of the air/sea exchange, turbulence, and sea-salt aerosol particle characteristics at the subtropical marine Pacific site. Here we examine coarse mode particle size distributions. Similar to what has been shown for airborne dust, optical particle counters such as the Forward Scatte...

  15. Parameterizing Size Distribution in Ice Clouds

    Energy Technology Data Exchange (ETDEWEB)

    DeSlover, Daniel; Mitchell, David L.

    2009-09-25

    PARAMETERIZING SIZE DISTRIBUTIONS IN ICE CLOUDS David L. Mitchell and Daniel H. DeSlover ABSTRACT An outstanding problem that contributes considerable uncertainty to Global Climate Model (GCM) predictions of future climate is the characterization of ice particle sizes in cirrus clouds. Recent parameterizations of ice cloud effective diameter differ by a factor of three, which, for overcast conditions, often translate to changes in outgoing longwave radiation (OLR) of 55 W m-2 or more. Much of this uncertainty in cirrus particle sizes is related to the problem of ice particle shattering during in situ sampling of the ice particle size distribution (PSD). Ice particles often shatter into many smaller ice fragments upon collision with the rim of the probe inlet tube. These small ice artifacts are counted as real ice crystals, resulting in anomalously high concentrations of small ice crystals (D < 100 µm) and underestimates of the mean and effective size of the PSD. Half of the cirrus cloud optical depth calculated from these in situ measurements can be due to this shattering phenomenon. Another challenge is the determination of ice and liquid water amounts in mixed phase clouds. Mixed phase clouds in the Arctic contain mostly liquid water, and the presence of ice is important for determining their lifecycle. Colder high clouds between -20 and -36 oC may also be mixed phase but in this case their condensate is mostly ice with low levels of liquid water. Rather than affecting their lifecycle, the presence of liquid dramatically affects the cloud optical properties, which affects cloud-climate feedback processes in GCMs. This project has made advancements in solving both of these problems. Regarding the first problem, PSD in ice clouds are uncertain due to the inability to reliably measure the concentrations of the smallest crystals (D < 100 µm), known as the “small mode”. Rather than using in situ probe measurements aboard aircraft, we employed a treatment of ice

  16. Methods for determining particle size distribution and growth rates between 1 and 3 nm using the Particle Size Magnifier

    CERN Document Server

    Lehtipalo, Katrianne; Kontkanen, Jenni; Kangasluoma, Juha; Franchin, Alessandro; Wimmer, Daniela; Schobesberger, Siegfried; Junninen, Heikki; Petäjä, Tuukka; Sipilä, Mikko; Mikkilä, Jyri; Vanhanen, Joonas; Worsnop, Douglas R; Kulmala, Markku

    2014-01-01

    The most important parameters describing the atmospheric new particle formation process are the particle formation and growth rates. These together determine the amount of cloud condensation nuclei attributed to secondary particle formation. Due to difficulties in detecting small neutral particles, it has previously not been possible to derive these directly from measurements in the size range below about 3 nm. The Airmodus Particle Size Magnifier has been used at the SMEAR II station in Hyytiälä, southern Finland, and during nucleation experiments in the CLOUD chamber at CERN for measuring particles as small as about 1 nm in mobility diameter. We developed several methods to determine the particle size distribution and growth rates in the size range of 1–3 nm from these data sets. Here we introduce the appearance-time method for calculating initial growth rates. The validity of the method was tested by simulations with the Ion-UHMA aerosol dynamic model.

  17. Plasmonic nanoparticle films for solar cell applications fabricated by size-selective aerosol deposition

    OpenAIRE

    Pfeiffer, T.V.; Ortiz Gonzalez, J.; Santbergen, R.; Tan, H.; Schmidt-Ott, A.; Zeman, M.; Smets, A.H.M.

    2014-01-01

    A soft deposition method for incorporating surface plasmon resonant metal nanoparticles within photovoltaic devices was studied. This self-assembly method provides excellent control over both nanoparticle size and surface coverage. Films of spherical Ag nanoparticles with diameter of ∼100 nm were fabricated by depositing size-selected aerosols on various substrates using electrophoresis. This novel deposition method opens the route to embed plasmonic nanoparticles in the intermediate reflecto...

  18. Influence of Size Effects on Uptake of Impurity Atoms by Aerosol Nanoparticles Growing in Vapor Condensation

    OpenAIRE

    Levdansky, V.V.

    2014-01-01

    It is known that impurity atoms (molecules) in the main substance can affect its physicochemical properties. Semiconductor doping is paramount in micro- and nanoelectronics. In some cases nanoparticle doping is needed. Nanoparticle doping in the general case depends on the size of nanoparticles. Below we consider theoretically size effects in the uptake of impurity (dopant) atoms by the aerosol nanoparticle that grows in the supersaturated vapor.

  19. Size distributions, sources and source areas of water-soluble organic carbon in urban background air

    Directory of Open Access Journals (Sweden)

    H. Timonen

    2008-09-01

    Full Text Available This paper represents the results of one year long measurement period of the size distributions of water-soluble organic carbon (WSOC, inorganic ions and gravimetric mass of particulate matter. Measurements were done at an urban background station (SMEAR III by using a micro-orifice uniform deposit impactor (MOUDI. The site is located in northern European boreal region in Helsinki, Finland. The WSOC size distribution measurements were completed with the chemical analysis of inorganic ions, organic carbon (OC and monosaccharide anhydrides from the filter samples (particle aerodynamic diameter smaller than 1 μm, PM1. Gravimetric mass concentration varied during the MOUDI samplings between 3.4 and 55.0 μg m−3 and the WSOC concentrations were between 0.3 and 7.4 μg m−3. On average, water-soluble particulate organic matter (WSPOM, WSOC multiplied by 1.6 to convert the analyzed carbon mass to organic matter mass comprised 25±7.7% and 7.5±3.4% of aerosol PM1 mass and the PM1–10 mass, respectively. Inorganic ions contributed 33±12% and 28±19% of the analyzed PM1 and PM1–10 aerosol mass.

    Five different aerosol categories corresponding to different sources or source areas were identified (long-range transport aerosols, biomass burning aerosols from wild land fires and from small-scale wood combustion, aerosols originating from marine areas and from the clean arctic areas. Categories were identified mainly using levoglucosan concentration level for wood combustion and air mass backward trajectories for other groups. Clear differences in WSOC concentrations and size distributions originating from different sources or source areas were observed, although there are also many other factors which might affect the results. E.g. the local conditions and sources of volatile organic compounds (VOCs and aerosols as well as various transformation processes are likely

  20. Size distributions, sources and source areas of water-soluble organic carbon in urban background air

    Directory of Open Access Journals (Sweden)

    H. Timonen

    2008-04-01

    Full Text Available This paper represents the results of one year long measurement period of the size distributions of water-soluble organic carbon (WSOC, inorganic ions and gravimetric mass of particulate matter. Measurements were done at an urban background station (SMEAR III by using a micro-orifice uniform deposit impactor (MOUDI. The site is located in northern European boreal region in Helsinki, Finland. The WSOC size distribution measurements were completed with the chemical analysis of inorganic ions, organic carbon (OC and monosaccharide anhydrides from the filter samples. During the measurements gravimetric mass in the MOUDI collections varied between 3.4 and 55.0 μg m−3 and the WSOC concentration was between 0.3 and 7.4 μg m−3. On average, water-soluble particulate organic matter (WSPOM, WSOC multiplied by 1.6 comprised 25±7.7% and 7.5±3.4% of aerosol PM1 mass and the PM1−10 mass, respectively. Inorganic ions contributed 33±12% and 28±19% of the analyzed PM1 and PM1−10 aerosol mass.

    Five different aerosol categories corresponding to different sources or source areas were identified (long-range transport aerosols, biomass burning aerosols from wild land fires and from small-scale wood combustion, aerosols originating from marine areas and from the clean arctic areas. Clear differences in WSOC concentrations and size distributions originating from different sources or source areas were observed, although there are also many other factors which might affect the results. E.g. the local conditions and sources of volatile organic compounds (VOCs and aerosols as well as various transformation processes are likely to have an impact on the measured aerosol composition. Using the source categories, it was identified that especially the oxidation products of biogenic VOCs in summer had a clear effect on WSOC concentrations.

  1. A REVIEW OF CURRENT KNOWLEDGE CONCERNING SIZE-DEPENDENT AEROSOL REMOVAL

    Institute of Scientific and Technical Information of China (English)

    Leiming Zhang; Robert Vet

    2006-01-01

    The status of current knowledge on size-dependent aerosol removal by dry and wet processes, including dry deposition and impaction and nucleation scavenging, is reviewed. The largest discrepancies between theoretical estimations and measurement data on dry deposition and below-cloud scavenging are for submicron particles. Early dry deposition models, which developed based on chamber and wind tunnel measurements, tended to underestimate dry deposition velocity (Vd) for submicron particles by around one order of magnitude compared to recent field measurements. Recently developed models are able to predict reasonable Vd values for submicron particles but shift unrealistically the predicted minimum Vd to larger particle sizes. Theoretical studies of impaction scavenging of aerosol particles by falling liquid drops also substantially underestimate the scavenging coefficients for submicron particles. Empirical formulas based on field measurements can serve as an alternative to the theoretical scavenging models. Future development of size-resolved impaction scavenging models needs to include more precipitation properties (e.g., droplet surface area) and to be evaluated by detailed cloud microphysical models and available measurements. Several recently developed nucleation scavenging parameterizations for in-cloud removal of interstitial aerosol give comparable results when evaluated against parcel models; however, they need to be verified once suitable field measurements are available.More theoretical and field studies are also needed in order to better understand the role of organic aerosols in the nucleation scavenging process.

  2. Aerosol vertical distribution characteristics over the Tibetan Plateau

    International Nuclear Information System (INIS)

    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

  3. Aerosol composition at Chacaltaya, Bolivia, as determined by size-fractionated sampling

    Science.gov (United States)

    Adams, F.; van Espen, P.; Maenhaut, W.

    Thirty-four cascade-impactor samples were collected between September 1977 and November 1978 at Chacaltaya, Bolivia. The concentrations of 25 elements were measured for the six impaction stages of each sample by means of energy-dispersive X-ray fluorescence and proton-induced X-ray emission analysis. The results indicated that most elements are predominantly associated with a unimodal coarse-particle soil-dustdispersion component. Also chlorine and the alkali and alkaline earth elements belong to this group. The anomalously enriched elements (S, Br and the heavy metals Cu, Zn, Ga, As, Se, Pb and Bi) showed a bimodal size distribution. Correlation coefficient calculations and principal component analysis indicated the presence in the submicrometer aerosol mode of an important component, containing S, K, Zn, As and Br, which may originate from biomass burning. For certain enriched elements (i.e. Zn and perhaps Cu) the coarse-particle enrichments observed may be the result of the true crust-air fractionation during soil-dust dispersion.

  4. Characterizing the Vertical Distribution of Aerosols Over the ARM SGP Site

    Energy Technology Data Exchange (ETDEWEB)

    Richard Ferrare, Connor Flynn, David Turner

    2009-05-05

    This project focused on: 1) evaluating the performance of the DOE ARM SGP Raman lidar system in measuring profiles of water vapor and aerosols, and 2) the use of the Raman lidar measurements of aerosol and water vapor profiles for assessing the vertical distribution of aerosols and water vapor simulated by global transport models and examining diurnal variability of aerosols and water vapor. The highest aerosol extinction was generally observed close to the surface during the nighttime just prior to sunrise. The high values of aerosol extinction are most likely associated with increased scattering by hygroscopic aerosols, since the corresponding average relative humidity values were above 70%. After sunrise, relative humidity and aerosol extinction below 500 m decreased with the growth in the daytime convective boundary layer. The largest aerosol extinction for altitudes above 1 km occurred during the early afternoon most likely as a result of the increase in relative humidity. The water vapor mixing ratio profiles generally showed smaller variations with altitude between day and night. We also compared simultaneous measurements of relative humidity, aerosol extinction, and aerosol optical thickness derived from the ARM SGP Raman lidar and in situ instruments on board a small aircraft flown routinely over the ARM SGP site. In contrast, the differences between the CARL and IAP aerosol extinction measurements are considerably larger. Aerosol extinction derived from the IAP measurements is, on average, about 30-40% less than values derived from the Raman lidar. The reasons for this difference are not clear, but may be related to the corrections for supermicron scattering and relative humidity that were applied to the IAP data. The investigators on this project helped to set up a major field mission (2003 Aerosol IOP) over the DOE ARM SGP site. One of the goals of the mission was to further evaluate the aerosol and water vapor retrievals from this lidar system

  5. EDXRF elemental profiles and characterization of size-segregated particulate matter of aerosols in Khartoum area

    International Nuclear Information System (INIS)

    In this work analysis of size segregated particles from the aerosols in Khartoum area was performed using EDXRFA, to determine the particulate matter concentration levels as well as to compare them with other African countries. During the study three measurement campaigns, inside and out side Sudan, were carried out during the period April-July-2001 in Khartoum, and October 2001 in Dar Es-Salaam, (Tanzania). In addition soil samples were collected from ten locations in the proximity of dense roads at the center of Khartoum city and from a desert area 120 km north of Khartoum. The sampling and segregation of particles were done using a dichotomous virtual impactor and a cyclone. Elemental concentrations of fourteen elements in he samples were determined by EDXRFA. Concentrations of back carbon (B C) were also measured at the two size fractions. The elements Si, K, Ca, Ti, Mn, Fe, Zn and Sr were found to be dominant in the collected particulates. Day period collections were found to have higher elemental concentrations than those of night periods. The statistical analysis of the results indicated that all elements in the proximity of roadsides had elevated concentrations compared to the background air levels. The results indicated an influence of vehicular traffic emission for the elements Zn, Ni and Pb and a correlation between lead and bromine. The lead to bromine ratio was found to be with the range of those derived from vehicular exhaust and in good agreement with the ratios obtained in some African countries. The lead distributions in the roadside soils confirmed source as automobile emission. However, it was observed that the levels were having different trends with respect to both the depth from the surface layer of the the earth and the distance from the edge of the road. It was found that Khartoum aerosols had relatively high levels of air particulates originating from the soil. Dar Es-Salaam (Tanzania), and to a lesser extent Gaborone (Botswana), results

  6. Sensitivity of Stratospheric Geoengineering with Black Carbon to Aerosol Size and Altitude of Injection

    Science.gov (United States)

    Kravitz, Ben; Robock, Alan; Shindell, Drew T.; Miller, Mark A.

    2012-01-01

    Simulations of stratospheric geoengineering with black carbon (BC) aerosols using a general circulation model with fixed sea surface temperatures show that the climate effects strongly depend on aerosol size and altitude of injection. 1 Tg BC/a injected into the lower stratosphere would cause little surface cooling for large radii but a large amount of surface cooling for small radii and stratospheric warming of over 60 C. With the exception of small particles, increasing the altitude of injection increases surface cooling and stratospheric warming. Stratospheric warming causes global ozone loss by up to 50% in the small radius case. The Antarctic shows less ozone loss due to reduction of polar stratospheric clouds, but strong circumpolar winds would enhance the Arctic ozone hole. Using diesel fuel to produce the aerosols is likely prohibitively expensive and infeasible. Although studying an absorbing aerosol is a useful counterpart to previous studies involving sulfate aerosols, black carbon geoengineering likely carries too many risks to make it a viable option for deployment.

  7. Influence of Glassy Organic Species on Ice Nucleation and Water Uptake of Single Micron-sized Aerosol Particles

    Science.gov (United States)

    Baustian, K. J.; Wise, M. E.; Tolbert, M. A.

    2011-12-01

    Organic material is ubiquitous in tropospheric aerosol and has significant natural and anthropogenic sources. Until recently it was believed that organic species present in or on aerosol particles acted only to inhibit ice nucleation. However, recent studies have shown that the relationship between ice formation and organic material is not straightforward. It seems that organic material can serve to either promote or inhibit heterogeneous ice formation depending on its chemical composition and spatial distribution within a particle. Due to the large abundance and complexity of organic material in the atmosphere, it is important that we understand more specifically how organic species influence ice cloud formation and, in turn, global climate. Recent work has shown that aerosol particles consisting of soluble oxygenated organic compounds may form non-crystalline solids known as 'glasses' at atmospherically relevant temperatures. These highly viscous organic particles may act as surfaces for ice formation at cold temperatures and low supersaturations with respect to ice. This study focuses on the ice nucleation and water uptake behavior of such aerosol particles. Raman spectroscopy and optical microscopy was used to examine water uptake and depositional ice nucleation on individual micron-sized particles at low temperatures (210-250 K). Three different types of oxygenated organic particles were examined: sucrose, citric acid and dextrose. Internally mixed particles consisting of each organic species and ammonium sulfate were also investigated. We report moisture-induced phase transitions and onset heterogeneous freezing conditions for each particle type. Raman spectral mapping was used to assess the spatial distribution of chemical constituents within internally mixed particles. The relationship between O:C ratio and moisture-induced phase transition was also examined. We present our results for organic ice nucleation efficiencies as influenced by chemical

  8. Aerosol vertical distribution, optical properties and transport over Corsica (western Mediterranean)

    OpenAIRE

    Léon, J.-F.; Augustin, P.; Mallet, M.; Bourrianne, T.; Pont, V.; Dulac, F.; Fourmentin, M; D. Lambert(School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom); Sauvage, B.

    2015-01-01

    This paper presents the aerosol vertical distribution observed in the western Mediterranean between February and April 2011 and between February 2012 and August 2013. An elastic backscattering lidar was continuously operated at a coastal site in the northern part of Corsica Island (Cap Corse) for a total of more than 14 000 h of observations. The aerosol extinction coefficient retrieved from cloud-free lidar profiles are analyzed along with the SEVIRI satellite aerosol optical depth (AO...

  9. Observations and Modeling of the Green Ocean Amazon 2014/15. Nanoparticle Size Distribution (NPSD) Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Kuang, C [Brookhaven National Lab. (BNL), Upton, NY (United States); Artaxo, P [University of Sao Paulo (Brazil); Martin, S [Harvard Univ., Cambridge, MA (United States); Wang, J [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-04-01

    Aerosol nucleation and initial growth were investigated during the Green Ocean Amazon (GoAmazon) 2014/15 campaign. Aerosol sampling occurred during the wet and dry seasons of 2014, and took place at the T3 measurement site, downwind of the city of Manaus, Brazil. Characterization of the aerosol size distribution from 10 to 500 nm was accomplished through the deployment of a conventional Scanning Mobility Particle Spectrometer (SMPS) and a fine condensation particle counter (> 10 nm). In order to directly measure aerosol nucleation and initial growth, a Nano SMPS (1.5-20 nm) was also deployed, consisting of a condensation particle counter-based electrical mobility spectrometer that was modified for the detection of sub-3 nm aerosol. Measurements of the aerosol size distribution from 1.5 nm to 10 nm were obtained during the first observational period, and from 3 nm to 15 nm during the second observational period. Routine, stable measurement in this size range was complicated due to persistent water condensation in the Nano SMPS and diffusional transport losses

  10. Aerosol structure and vertical distribution in a multi-source dust region.

    Science.gov (United States)

    Zhang, Jie; Zhang, Qiang; Tang, Congguo; Han, Yongxiang

    2012-01-01

    The vertical distribution of aerosols was directly observed under various atmospheric conditions in the free troposphere using surface micro-pulse lidar (MPL4) at the Zhangye Station (39.08 degrees N, 100.27 degrees E) in western China in the spring of 2008. The study shows that the aerosol distribution over Zhangye can be vertically classified into upper, middle and lower layers with altitudes of 4.5 to 9 km, 2.5 to 4.5 km, and less than 2.5 km, respectively. The aerosol in the upper layer originated from the external sources at higher altitude regions, from far desert regions upwind of Zhangye or transported from higher atmospheric layers by free convection, and the altitude of this aerosol layer decreased with time; the aerosols in the middle and lower layers originated from both external and local sources. The aerosol extinction coefficients in the upper and lower layers decreased with altitude, whereas the coefficient in the middle layer changed only slightly, which suggests that aerosol mixing occurs in the middle layer. The distribution of aerosols with altitude has three features: a single peak that forms under stable atmospheric conditions, an exponential decrease with altitude that occurs under unstable atmospheric conditions, and slight change in the mixed layer. Due to the impact of the top of the atmospheric boundary layer, the diurnal variation in the aerosol extinction coefficient has a single peak, which is higher in the afternoon and lower in the morning. PMID:23513689

  11. Influence of inspiratory flow rate, particle size, and airway caliber on aerosolized drug delivery to the lung.

    Science.gov (United States)

    Dolovich, M A

    2000-06-01

    A number of studies in the literature support the use of fine aerosols of drug, inhaled at low IFRs to target peripheral airways, with the objective of improving clinical responses to inhaled therapy (Fig. 8). Attempts have been made to separate response due to changes in total administered dose or the surface concentration of the dose from response due to changes in site of deposition--both are affected by the particle size of the aerosol, with IFR additionally influencing the latter. The tools for measuring dose and distribution have improved over the last 10-15 years, and thus we should expect greater accuracy in these measurements for assessing drug delivery to the lung. There are still issues, though, in producing radiolabeled (99m)technetium aerosols that are precise markers for the pharmaceutical product being tested and in quantitating absolute doses deposited in the lung. PET isotopes may provide the means for directly labelling a drug and perhaps can offer an alternative for making these measurements in the future, but deposition measurements should not be used in isolation; protocols should incorporate clinical tests to provide parallel therapeutic data in response to inhalation of the drug by the various patient populations being studied. PMID:10894453

  12. Size-resolved aerosol chemistry on Whistler Mountain, Canada with a High-Resolution Aerosol Mass Spectrometer during INTEX-B

    Directory of Open Access Journals (Sweden)

    Y. Sun

    2008-12-01

    Full Text Available An Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS was deployed at the peak of Whistler Mountain (elevation 2182 m-MSL, British Columbia, from 19 April to 16 May 2006, as part of the Intercontinental Chemical Transport Experiment Phase B (INTEX-B campaign. The mass concentrations and size distributions of non-refractory submicron particle (NR-PM1 species (i.e., sulfate, nitrate, ammonium, chloride, and organics were measured in situ every 5 min. The HR-ToF-AMS results agreed well with collocated measurements. The average concentration of non-refractory submicron particulate matter (NR-PM1; 1.9 μg m−3 is similar to those observed at other remote, high elevation sites in North America. Episodes of enhanced aerosol loadings were observed, due to influences of regional and trans-Pacific transport of air pollution. Organics and sulfate were the dominant species, on average accounting for 55% and 30%, respectively, of the NR-PM1 mass. The average size distributions of sulfate and ammonium both showed a~large accumulation mode peaking around 500–600 nm in Dva while those of organic aerosol (OA and nitrate peaked at ~300 nm. The size differences suggest that sulfate and OA were mostly present in external mixtures from different source origins. We also quantitatively determined the elemental composition of OA using the high resolution mass spectra. Overall, OA at Whistler Peak was highly oxygenated, with an average organic-mass-to-organic-carbon ratio (OM/OC of 2.28±0.23 and an atomic ratio of oxygen-to-carbon (O/C of 0.83±0.17. The nominal formula for OA was C1H1.66N0.03O0.83 for the entire study. Two significant trans-Pacific dust events originated from Asia were observed at Whistler Peak during this study. While both events were characterized with significant enhancements of coarse mode particles and mineral

  13. Analysis of size-fractionated coal combustion aerosols by PIXE and other analytical techniques

    International Nuclear Information System (INIS)

    Particle-induced X-ray emission (PIXE) analysis, instrumental neutron activation analysis (INAA) and inductively coupled plasma mass spectrometry (ICP-MS) were used to study the chemical composition of size-fractionated in-stack fly-ash particles emitted during coal combustion. The samples were collected before the electrostatic precipitator at a gas temperature of 120deg C during the combustion of Venezuelan coal in a 81 MW capacity circulating fluidized bed boiler. The sampling device consisted of a Berner low pressure impactor, which was operated with a cyclone precutter. The Nuclepore polycarbonate foils, which were used as collection surfaces in the low pressure impactor, were analyzed by the three techniques, and the results of common elements were critically compared. The PIXE results were systematically lower than the INAA data, and the percentage difference appeared to be stage-dependent, but virtually independent upon the element. The discrepancies are most likely due to bounce-off effects, particle reentrainment and other sampling artifacts, which may make that a fraction of the aerosol particles is deposited on the impaction foils outside the section analyzed by PIXE. However, by restoring to a 'mixed internal standard' approach, accurate PIXE data are obtained. Also in the comparison between the ICP-MS and the INAA data significant discrepancies were observed. These are most likely due to incomplete dissolution of the particulate material, and in particular of the alumino-silicate fly-ash matrix, during the acid digestion sample preparation step for ICP-MS. It is suggested that a comparison between ICP-MS data of acid digested samples and INAA can advantageously be used to provide speciation information on the various elements. Selected examples of size distributions are presented and briefly discussed. (orig.)

  14. Analysis of Fine and Coarse mode Aerosol Distributions from AERONET's mini-DRAGON Set-up at Singapore 2012

    Science.gov (United States)

    Salinas Cortijo, S. V.; Chew, B. N.; Muller, A.; Liew, S.

    2013-12-01

    Aerosol optical depth combined with the Angstrom exponent and its derivative, are often used as a qualitative indicator of aerosol type and particle size regime. In Singapore, the sources of aerosols are mostly from fossil fuel burning (energy stations, incinerators, urban transport etc.) and from industrial and urban areas. However, depending on the time of the year (July-October), there can be a strong bio-mass component originated from uncontrolled forest/plantation fires from the neighboring land masses of Sumatra and Borneo. Unlike urban/fossil fuel aerosols, smoke or bio-mass related aerosol particles are typically characterized by showing a large optical depth and small, sub-micron particle size distributions. Trans-boundary smoke episodes has become an annual phenomenon in this region. Severe episodes were recorded in 1997 and 2006 and other minor episodes happened during 2002, 2004, 2010 and more recently on 2013. On August-September 2012, as part of CRISP participation on the August-September ground campaign of the Southeast Asia Composition, Cloud Climate Coupling Regional Study (SEAC4RS), a Distributed Regional Aerosol Gridded Observation Networks (DRAGON) set of six CIMEL CE-318A automatic Sun-tracking photometers have been deployed at sites located at North (Yishun ITE), East (Temasek Poly), West (NUS and Pandan Reservoir), Central (NEA) and South (St. John's island) of Singapore. In order to fully discriminate bio-mass burning events over other local sources, we perform a spectral discrimination of fine/coarse mode particle regime to all DRAGON sites; subsequently, the fine mode parameters such as optical depth, optical ratio and fine mode Angstrom exponent are used to identify possible bio-mass related events within the data set. Spatio-temporal relationship between sites are also investigated.

  15. Functional characterization of the water-soluble organic carbon of size fractionated aerosol in the Southern Mississippi Valley

    Science.gov (United States)

    Chalbot, M.-C. G.; Brown, J.; Chitranshi, P.; Gamboa da Costa, G.; Pollock, E. D.; Kavouras, I. G.

    2014-02-01

    The chemical content of the water soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to: (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for the period when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5% of particle mass for particles with dp > 0.96 μm and 10% of particle mass for particles with dp unsaturated aliphatic (H-C-C=), oxygenated saturated aliphatic (H-C-O), acetalic (O-CH-O) and aromatic (Ar-H) protons were determined by proton nuclear magnetic resonance. The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m-3 for particles with 0.96 amines, ammonium and methanosulfonate were tentatively identified in NMR fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosol and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from -26.81 ± 0.18‰ for the smallest particles to -25.93 ± 0.31‰ for the largest particles and the relative distribution of the functional groups as compared to those previously observed for marine, biomass burning and secondary organic aerosol. The latter also allowed for the differentiation of urban combustion-related aerosol and biological particles. The five types of organic hydrogen accounted for the majority of WSOC for particles with dp > 3.0 μm and dp < 0.96 μm.

  16. Functional characterization of the water-soluble organic carbon of size-fractionated aerosol in the southern Mississippi Valley

    Science.gov (United States)

    Chalbot, M.-C. G.; Brown, J.; Chitranshi, P.; Gamboa da Costa, G.; Pollock, E. D.; Kavouras, I. G.

    2014-06-01

    The chemical content of water-soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for periods when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5% of particle mass for particles with dp > 0.96 μm and 10% of particle mass for particles with dp unsaturated aliphatic (H-C-C=), oxygenated saturated aliphatic (H-C-O), acetalic (O-CH-O) and aromatic (Ar-H) protons were determined by proton nuclear magnetic resonance (1H-NMR). The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m-3 for particles with 1.5 amines, ammonium and methanesulfonate were identified in NMR fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosols and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from -26.81 ± 0.18‰ for the smallest particles to -25.93 ± 0.31‰ for the largest particles and the relative distribution of the functional groups as compared to those previously observed for marine, biomass burning and secondary organic aerosol. The latter also allowed for the differentiation of urban combustion-related aerosol and biological particles. The five types of organic hydrogen accounted for the majority of WSOC for particles with dp > 3.0 μm and dp < 0.96 μm.

  17. The Hohenpeissenberg aerosol formation experiment (HAFEX: a long-term study including size-resolved aerosol, H2SO4, OH, and monoterpenes measurements

    Directory of Open Access Journals (Sweden)

    A. Wiedensohler

    2002-10-01

    Full Text Available Ambient aerosol size distributions (> 3 nm and OH, H2SO4, and terpene concentrations were measured from April 1998 to August 2000 at a rural continental site in southern Germany. New particle formation (NPF events were detected on 18% of all days, typically during midday hours under sunny and dry conditions. Surprisingly, most NPF events occurred during spring and winter, whereas the concentrations of aerosol precursors (H2SO4, monoterpenes clearly peaked in summer. The number of newly formed particles correlated significantly with solar irradiance and ambient levels of H2SO4 and anti-correlated, especially in the cold season, with relative humidity and the condensational sink provided by pre-existing particles. The particle formation rates were experimentally estimated to be on order of 1 cm-3 s-1. Binary homogeneous H2SO4-H2O nucleation rates calculated from measured H2SO4 were substantially lower than this, even if assuming particle formation under the thermodynamic conditions on top of the boundary layer. The nucleation mode particle growth rates derived from the evolution of the size distribution were 2.6 nm h-1 on average, with a fraction of 0.7 nm h-1 attributed to the co-condensation of H2SO4/H2O/NH3. Turn-over rate calculations of measured monoterpenes and aromatic hydrocarbons suggest that especially the oxidation products of monoterpenes may contribute to the observed particle growth, although no indications were found that the reaction products of organic compounds would generally control the occurrence of NPF events.

  18. Electronic structure and size of TiO sub 2 nanoparticles of controlled size prepared by aerosol methods

    CERN Document Server

    Soriano, L; Sanchez-Agudo, M; Sanz, J M; Ahonen, P P; Kauppinen, E I; Palomares, F J; Bressler, P R

    2002-01-01

    A complete characterization of nanostructures has to deal both with electronic structure and dimensions. Here we present the characterization of TiO sub 2 nanoparticles of controlled size prepared by aerosol methods. The electronic structure of these nanoparticles was probed by x-ray absorption spectroscopy (XAS), the particle size by atomic force microscopy (AFM). XAS spectra show that the particles crystallize in the anatase phase upon heating at 500 sup o C, whereas further annealing at 700 sup o C give crystallites of 70 % anatase and 30 % rutile phases. Raising the temperature to 900 sup o C results in a complete transformation of the particles to rutile. AFM images reveal that the mean size of the anatase particles formed upon heating at 500 sup o C is 30 nm, whereas for the rutile particles formed upon annealing at 900 sup o C 90 nm were found. The results obtained by these techniques agree with XRD data. (author)

  19. Determination of size distribution of elliptical microvessels from size distribution measurement of their section profiles.

    Science.gov (United States)

    Krasnoperov, R A; Gerasimov, A N

    2003-01-01

    In transmission electron microscopy, microvessels (MVs) are studied as profiles on ultrathin sections. To determine MV sizes from measurements made on MV profiles, an assumption must be made about MV shape, a circular cylinder being used to approximate the latter on limited lengths. However, this model is irrelevant in case MVs have some flatness. The elliptical cylinder model is preferable, although relationships between the cylinder profile (two-dimensional; 2D) and its true (three-dimensional; 3D) sizes are not yet known. We have obtained the 2D/3D functions that express the relationships between such profile sizes as the minor radius (Y), major radius (X), axial ratio (X/Y), area (S), and perimeter (P) on the one hand, and the corresponding MV sizes (Y(0), X(0), X(0)/Y(0), S(0), and P(0)) on the other. The 2D/3D functions make it possible to derive elliptical MV sizes from section profile size distributions, probability density functions (PDFs) for the latter being determined. We have applied the 2D/3D functions in studying axial ratios of thyroid hemocapillaries. A factual X/Y frequency histogram has been constructed and fitted by theoretical X/Y PDFs plotted for different sets of capillary sizes. The thyroid capillaries have been revealed to be clustered, 72.7% of them having X(0)/Y(0) approximately 1.6, 17.6%, X(0)/Y(0) approximately 1.0, and 9.7%, X(0)/Y(0) approximately 3.2. The proposed technique is instrumental in precise modeling of microcirculatory network geometry. PMID:12524478

  20. Elemental mass size distribution of atmospheric aerosol in Prague

    Czech Academy of Sciences Publication Activity Database

    Schwarz, J.; Džumbová, L.; Kugler, Andrej; Smolík, J.; Hillamo, R.; Sillanpää, M.; Šantroch, J.; Havránek, Vladimír

    2001-01-01

    Roč. 32, č. 1 (2001), s. 167-168. ISSN 0021-8502 Institutional research plan: CEZ:AV0Z1048901 Keywords : Elemental mass Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.605, year: 2001

  1. The Size Distribution of Bovine Casein Micelles: A Review

    OpenAIRE

    Holt, C.

    1985-01-01

    This review considers the average size and size distribution of bovine casein micelles as measured by electron microscopy, light scattering and controlled pore glass chromatography, and the origin and biological function of the size distribution. Recent work by electron microscopy has given average sizes in reasonable agreement with measurements on the same milk sample by light scattering . It is suggested that natural variations in averaqe micelle size and overestimation of micelle radii ...

  2. ED-XRF set-up for size-segregated aerosol samples analysis

    OpenAIRE

    Bernardoni, V.; E. Cuccia; G. Calzolai; Chiari, M.; Lucarelli, F.; D. Massabo; Nava, S.; Prati, P.; Valli, G; Vecchi, R.

    2011-01-01

    The knowledge of size-segregated elemental concentrations in atmospheric particulate matter (PM) gives a useful contribution to the complete chemical characterisation; this information can be obtained by sampling with multi-stage cascade impactors. In this work, samples were collected using a low-pressure 12-stage Small Deposit Impactor and a 13-stage rotating Micro Orifice Uniform Deposit Impactor™. Both impactors collect the aerosol in an inhomogeneous geometry, which needs a special set-up...

  3. Numerical Model to Characterize the Size Increase of Combination Drug and Hygroscopic Excipient Nanoparticle Aerosols

    OpenAIRE

    Longest, P. Worth; Hindle, Michael

    2011-01-01

    Enhanced excipient growth is a newly proposed respiratory delivery strategy in which submicrometer or nanometer particles composed of a drug and hygroscopic excipient are delivered to the airways in order to minimize extrathoracic depositional losses and maximize lung retention. The objective of this study was to develop a validated mathematical model of aerosol size increase for hygroscopic excipients and combination excipient-drug particles and to apply this model to characterize growth und...

  4. Systematic Relationships Between Lidar Observables And Sizes And Mineral Composition Of Dust Aerosols

    Science.gov (United States)

    van Diedenhoven, B.; Perlwitz, J. P.; Fridlind, A. M.; Chowdhary, J.; Cairns, B.; Stangl, A. J.

    2015-12-01

    The physical and chemical properties of soil dust aerosol particles fundamentally affect their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates on the surface of dust particles, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Lidar measurements, such as extinction-to-backscatter, color and depolarization ratios, are frequently used to distinguish between aerosol types with different physical and chemical properties. The chemical composition of aerosol particles determines their complex refractive index, hence affecting their backscattering properties. Here we present a study on how dust aerosol backscattering and depolarization properties at wavelengths of 355, 532 and 1064 nm are related to size and complex refractive index, which varies with the mineral composition of the dust. Dust aerosols are represented by collections of spheroids with a range of prolate and oblate aspect ratios and their optical properties are obtained using T-matrix calculations. We find simple, systematic relationships between lidar observables and the dust size and complex refractive index that may aid the use of space-based or airborne lidars for direct retrieval of dust properties or for the evaluation of chemical transport models using forward simulated lidar variables. In addition, we present first results on the spatial variation of forward-simulated lidar variables based on a dust model that accounts for the atmospheric cycle of eight different mineral types plus internal mixtures of seven mineral types with iron oxides, which was recently implemented in the NASA GISS Earth System ModelE2.

  5. Isotope source apportionment of carbonaceous aerosol as a function of particle size and thermal refractiveness

    Science.gov (United States)

    Masalaite, Agne; Holzinger, Rupert; Remeikis, Vidmantas; Röckmann, Thomas; Dusek, Ulrike

    2016-04-01

    The stable carbon isotopes can be used to get information about sources and processing of carbonaceous aerosol. We will present results from source apportionment of carbonaceous aerosol as a function of particle size thermal refractiveness. Separate source apportionment for particles smaller than 200 nm and for different carbon volatility classes are rarely reported and give new insights into aerosol sources in the urban environment. Stable carbon isotope ratios were measured for the organic carbon (OC) fraction and total carbon (TC) of MOUDI impactor samples that were collected on a coastal site (Lithuania) during the winter 2012 and in the city of Vilnius (Lithuania) during the winter of 2009. The 11 impactor stages spanned a size range from 0.056 to 18 μm, but only the 6 stages in the submicron range were analysed. The δ13C values of bulk total carbon (δ13CTC) were determined with an elemental analyser (Flash EA 1112) coupled with an isotope ratio mass spectrometer (Thermo Finnigan Delta Plus Advantage) (EA - IRMS). Meanwhile δ13COC was measured using thermal-desorption isotope ratio mass spectrometry (IRMS) system. This allows a rough separation of the more volatile OC fraction (desorbed in the oven of IRMS up to 250 0C) from the more refractory fraction (desorbed up to 400 0C). In this study we investigated the composition of organic aerosol desorbed from filter samples at different temperatures using the thermal-desorption proton-transfer-reaction mass spectrometry (TD-PTR-MS) technique. During winter-time in Lithuania we expect photochemistry and biogenic emissions to be of minor importance. The main sources of aerosol carbon should be fossil fuel and biomass combustion. In both sites, the coastal and the urban site, δ13C measurements give a clear indication that the source contributions differ for small and large particles. Small particles NWO grants Nr. 820.01.001, and 834.08.002).

  6. Impact of aerosol vertical distribution on aerosol direct radiative effect and heating rate in the Mediterranean region

    Science.gov (United States)

    Pappas, Vasileios; Hatzianastassiou, Nikolaos; Matsoukas, Christos; Koras Carracca, Mario; Kinne, Stefan; Vardavas, Ilias

    2015-04-01

    It is now well-established that aerosols cause an overall cooling effect at the surface and a warming effect within the atmosphere. At the top of the atmosphere (TOA), both positive and negative forcing can be found, depending on a number of other factors, such as surface albedo and relative position of clouds and aerosols. Whilst aerosol surface cooling is important due to its relation with surface temperature and other bio-environmental reasons, atmospheric heating is of special interest as well having significant impacts on atmospheric dynamics, such as formation of clouds and subsequent precipitation. The actual position of aerosols and their altitude relative to clouds is of major importance as certain types of aerosol, such as black carbon (BC) above clouds can have a significant impact on planetary albedo. The vertical distribution of aerosols and clouds has recently drawn the attention of the aerosol community, because partially can account for the differences between simulated aerosol radiative forcing with various models, and therefore decrease the level of our uncertainty regarding aerosol forcing, which is one of our priorities set by IPCC. The vertical profiles of aerosol optical and physical properties have been studied by various research groups around the world, following different methodologies and using various indices in order to present the impact of aerosols on radiation on different altitudes above the surface. However, there is still variability between the published results as to the actual effect of aerosols on shortwave radiation and on heating rate within the atmosphere. This study uses vertical information on aerosols from the Max Planck Aerosol Climatology (MAC-v1) global dataset, which is a combination of model output with quality ground-based measurements, in order to provide useful insight into the vertical profile of atmospheric heating for the Mediterranean region. MAC-v1 and the science behind this aerosol dataset have already

  7. Metal concentration and bioaccessibility in different particle sizes of dust and aerosols to refine metal exposure assessment.

    Science.gov (United States)

    Goix, Sylvaine; Uzu, Gaëlle; Oliva, Priscia; Barraza, Fiorella; Calas, Aude; Castet, Sylvie; Point, David; Masbou, Jeremy; Duprey, Jean-Louis; Huayta, Carlos; Chincheros, Jaime; Gardon, Jacques

    2016-11-01

    Refined exposure assessments were realized for children, 7-9yrs, in the mining/smelting city of Oruro, Bolivia. Aerosols (PM>2.5, PM1-2.5, PM0.4-1 and PM0.5) and dust (separated in different particle size fractions: 2000-200μm, 200-50μm, 50-20μm, 20-2μm and assessed considering actual external exposure (i.e. exposure pathways: metals inhaled and ingested) and simulated internal exposure (i.e., complex estimation using gastric and lung bioaccessibility, deposition and clearance of particles in lungs). Significant differences between external and simulated internal exposure were attributed to dissemblances in gastric and lung bioaccessibilities, as well as metal distribution within particle size range, revealing the importance of both parameters in exposure assessment. PMID:27344256

  8. Evaluation of droplet size distributions using univariate and multivariate approaches

    DEFF Research Database (Denmark)

    Gauno, M.H.; Larsen, C.C.; Vilhelmsen, T.;

    2013-01-01

    of the distribution. The current study was aiming to compare univariate and multivariate approach in evaluating droplet size distributions. As a model system, the atomization of a coating solution from a two-fluid nozzle was investigated. The effect of three process parameters (concentration of ethyl cellulose...... in ethanol, atomizing air pressure, and flow rate of coating solution) on the droplet size and droplet size distribution using a full mixed factorial design was used. The droplet size produced by a two-fluid nozzle was measured by laser diffraction and reported as volume based size distribution...

  9. Applications of aerosol model in the reactor containment

    OpenAIRE

    Mossad Slama; Mohammad Omar Shaker; Ragaa Aly; Magdy Sirwah

    2014-01-01

    The study simulates of aerosol dynamics including coagulation, deposition and source reinforcement. Typical applications are for nuclear reactor aerosols, aerosol reaction chambers and the production of purified materials. The model determines the aerosol number and volume distributions for an arbitrary number of particle-size classes, called sections. The user specifies the initial aerosol size distribution and the source generation rate of each component in each section. For spatially ho...

  10. SEGREGATION IN A FLUIDIZED POWDER OF A CONTINUOUS SIZE DISTRIBUTION

    NARCIS (Netherlands)

    HOFFMANN, AC; ROMP, EJ

    1991-01-01

    The state of mixing in a gas fluidised bed of sand of a continuous size distribution has been investigated at various fluidisation velocities. The results are shown mainly as axial concentration profiles of the individual size fractions obtained by sieving. It was found that the local size distribut

  11. Seasonal variation of aerosol vertical distributions in the middle and lower troposphere in Beijing and surrounding area during haze periods based on CALIPSO observation

    Science.gov (United States)

    Liu, Qiong; Ma, Xiaojun; Jin, Hongchun; Chen, Yonghang; Yu, Yang; Zhang, Hua; Cai, Changjie; Wang, Yuhui; Li, Hao

    2014-11-01

    The data from CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) satellite was used to analyze the aerosol micro-physical properties over Beijing and surrounding area during haze periods from 2007 to 2008 in this paper. The results showed as follows. The values of TABC (total attenuated backscatter coefficient) for aerosols accounted for about 25% with varying altitudes. The aerosol scattering ability little changed from 0-4 km, showing that the aerosol layer evenly distribute. At different altitude ranges (0-1, 1-2, 2-3 and 3-4 km above ground level), values of TABC almost concentrate in the range of 2.5×10-3 -4.5×10-3 km-1.sr-1. In spring, summer and winter, aerosol scattering has the similar variation, with the maximum of TABC ranging from 3.5×10-3 km-1.sr-1 to 4.5×10-3 km-1.sr-1, while the maximum of TABC in autumn is from 1.5×10-3 km-1.sr-1 to 2.5×10-3 km-1.sr-1. Aerosol shape and size are characterized by VDR (volume depolarization ratio) and TACR (total attenuated color ratio). Aerosols with VDR greater than 10% were more than the ones with VDR less than 10% at the same altitude range. Notably, aerosols with smaller VDR (0-10%) appeared more frequently in autumn than those in the other three seasons. For each altitude range, aerosols with TACR ranging from 0-0.2 contributed much more than those with TACR ranging from 1.8-2.0. The size of aerosols in summer was the largest and that in autumn was the smallest in middle and lower troposphere.

  12. Intercomparison exercise of measurement techniques for radon, radon decay products and their particles size distributions at NIRS

    International Nuclear Information System (INIS)

    An intercomparison exercise of radon, radon decay products and particle size distribution was carried out using the radon/aerosol chamber at National Institute of Radiological Sciences, 2002. Nine institutions participated in this exercise. Radon concentrations were first compared using a domestic ionization chamber, which was regarded as the primary standard equipment in Japan. Subsequently, several types of passive radon detectors were placed in the radon/aerosol chamber and their readings were compared with each other. Radon decay products concentrations were also intercompared, though the number of participants was small. After injection of Carnauba wax aerosols with the evaporation-condensation method, the particle size distribution of radon progeny was compared with three different sampling techniques: graded screen array, diffusion battery and cascade impactor. The present paper describes an overview of the experiment and the present status of correspondence on radon devices. (author)

  13. Correlation of acid rain with the distributions of acid and alkaline elements in aerosols

    International Nuclear Information System (INIS)

    Acid rain often appeared both in Guiyang city of Guizhou province and Chongqing city of Sichuan province in the southwest of China. Aerosol samples in these two cities were collected by Andersen cascade sampler during the spring and autumn of 1995 respectively. The contents of 18 elements in the aerosol particles were analyzed by PIXE. The distributions of acid elements such as S, Cl and alkaline elements such as Ca, K in the aerosol samples from these two cities were calculated. The comparison of the distributions of acid and alkaline elements in the aerosols samples was made between these two cities and Beijing where no acid rain was found. The results showed that the acid rain in the southwest of China was caused by the dominant concentration of acid elements in the aerosol particles, which mainly resulted from the coal combustion and the lower alkalinity of soil in this area

  14. A pseudo-Lagrangian model study of the size distribution properties over Scandinavia: transport from Aspvreten to Värriö

    OpenAIRE

    Tunved, P.; Korhonen, H.; StrÖm, J.; Hansson, H.-C.; Lehtinen, K. E. J.; Kulmala, M.

    2004-01-01

    The evolution of the aerosol size distribution during transport between Aspvreten (58.8° N, 17.4° E) and Värriö (67.46° N, 29.35° E) was studied using a pseudo-Lagrangian approach. Aerosol dynamic processes were studied and interpreted utilizing a state-of-the-art aerosol dynamic box model UHMA (University of Helsinki Multicomponent Aerosol model) complemented with OH, NO3, O3 and terpene chemistry...

  15. Modelling the evolution of 210Pb and 210Po size distributions in the atmosphere

    International Nuclear Information System (INIS)

    The study of radon (222Rn and 220Rn) decay products in the atmosphere is important for estimating air ionization, assessing the inhalation doses to humans and for understanding atmospheric transport processes. The decay products 218Po, 214Pb (T1/2 < 1 hour), 212Pb (T1/2 ∼ 10.6 hrs) are short lived and 210Po (T1/2 ∼ 13 days), 210Pb (T1/2 ∼ 22 years) are long lived. Within a short time after their formation, the decay product atom combine with air constituents to form molecular clusters which then get attached to existing aerosol particles. The activity size distributions of the short-lived components in the atmosphere show two major modes, namely fine and coarse modes. The long-lived components predominantly occur in the coarse mode. Several studies have been carried out on the decay product activity distributions to estimate their atmospheric residence times. An important aspect that has received little attention is the upward size evolution of the decay products due to the persistent coagulation of the coarse mode particles. The present study aims at the development of first principle model for progeny attachment dynamics to a coagulating aerosol, which will provide insight in understanding the evolution of activity size distribution. A theoretical model is formulated by considering the processes such a constant formation of background aerosols, attachment of progeny atoms to the aerosol, coagulation, physical decay, and deposition. A set of integro-differential equations for attached and unattached fractions are formulated and are solved by a comprehensive numerical approach. Comparative studies of the activity size distributions, the degree of mixing of radioactivity within particles are carried out for short-lived and long lived species. The results are in agreement with the observations which show that the mode of the activity size distribution strongly depends on the effective life time of the progeny species in the atmosphere. The size dependence of

  16. In-place testing of HEPA filter using monodisperse DOP aerosols in the most penetrating particle size range

    International Nuclear Information System (INIS)

    Recent filtration studies have revealed that the most penetrating particle size MPPS, through HEPA filter is smaller than 0.3 μm, which is the test aerosol size in the current filter testing. Furthermore, in the radiation protection field the filter performance is required to be linked to a DF (Decontamination Factor). To meet this evaluation criterion, a new in-place filter test system was developed. Our system consists of a newly designed aerosol generator and a computer-aided aerosol measuring system. The aerosol generator, which is a vaporization-condensation type, generates DOP (Dioctyl Phthalate) aerosols in the most penetrating particle size range from 0.1 to 0.2 μm with a geometric standard deviation (σg) less than 1.2. This high monodispersity makes possible to use a CNC (Condensation Nucleus Counter) for determination of aerosol penetration. Test aerosols are simultaneously measured by using a laser aerosol spectrometer in the upstream and the CNC in the downstream. It was shown that the collection efficiency of seven-nine percentage class for the MPPS range can be measured at air flow of 7800 m3/hr in in-place test. (4 figs., 2 tabs.)

  17. Study on distribution of aerosol optical depth in Chongqing urban area

    Science.gov (United States)

    Yang, Shiqi; Liu, Can; Gao, Yanghua

    2015-12-01

    This paper selected 6S (second simulation of the satellite signal in the solar spectrum) model with dark pixel method to inversion aerosol optical depth by MODIS data, and got the spatial distribution and the temporal distribution of Chongqing urban area. By comparing with the sun photometer and API data, the result showed that the inversion method can be used in aerosol optical thickness monitoring in Chongqing urban area.

  18. The Distribution of Bubble Sizes During Reionization

    CERN Document Server

    Lin, Yin; Furlanetto, Steven R; Sutter, P M

    2015-01-01

    A key physical quantity during reionization is the size of HII regions. Previous studies found a characteristic bubble size which increases rapidly during reionization, with apparent agreement between simulations and analytic excursion set theory. Using four different methods, we critically examine this claim. In particular, we introduce the use of the watershed algorithm -- widely used for void finding in galaxy surveys -- which we show to be an unbiased method with the lowest dispersion and best performance on Monte-Carlo realizations of a known bubble size PDF. We find that a friends-of-friends algorithm declares most of the ionized volume to be occupied by a network of volume-filling regions connected by narrow tunnels. For methods tuned to detect those volume-filling regions, previous apparent agreement between simulations and theory is spurious, and due to a failure to correctly account for the window function of measurement schemes. The discrepancy is already obvious from visual inspection. Instead, HI...

  19. Impact of wildfires on size-resolved aerosol composition at a coastal California site

    Science.gov (United States)

    Maudlin, L. C.; Wang, Z.; Jonsson, H. H.; Sorooshian, A.

    2015-10-01

    Size-resolved aerosol composition measurements were conducted at a coastal site in central California during the Nucleation in California Experiment (NiCE) between July and August of 2013. The site is just east of ship and marine emission sources and is also influenced by continental pollution and wildfires, such as those near the California-Oregon border which occurred near the end of NiCE. Two micro-orifice uniform deposit impactors (MOUDIs) were used, and water-soluble and elemental compositions were measured. The five most abundant water-soluble species (in decreasing order) were chloride, sodium, non-sea salt (nss) sulfate, ammonium, and nitrate. During wildfire periods, nss K mass concentrations were not enhanced as strongly as other species in the sub-micrometer stages and even decreased in the super-micrometer stages; species other than nss K are more reliable tracers for biomass burning in this region. Chloride levels were reduced in the fire sets likely due to chloride depletion by inorganic and organic acids that exhibited elevated levels in transported plumes. During wildfire periods, the mass size distribution of most dicarboxylic acids changed from unimodal to bimodal with peaks in the 0.32 μm and 1.0-1.8 μm stages. Furthermore, sulfate's peak concentration shifted from the 0.32 μm to 0.56 μm stage, and nitrate also shifted to larger sizes (1.0 μm to 1.8-3.2 μm stages). Mass concentrations of numerous soil tracer species (e.g., Si, Fe) were strongly enhanced in samples influenced by wildfires, especially in the sub-micrometer range. Airborne cloud water data confirm that soil species were associated with fire plumes transported south along the coast. In the absence of biomass burning, cloud condensation nuclei (CCN) composition is dominated by nss sulfate and ammonium, and the water-soluble organic fraction is dominated by methanesulfonate, whereas for the samples influenced by wildfires, ammonium becomes the dominant overall species, and

  20. Effects of explosively venting aerosol-sized particles through earth-containment systems on the cloud-stabilization height

    International Nuclear Information System (INIS)

    A method of approximating the cloud stabilization height for aerosol-sized particles vented explosively through earth containment systems is presented. The calculated values for stabilization heights are in fair agreement with those obtained experimentally

  1. Effects of explosively venting aerosol-sized particles through earth-containment systems on the cloud-stabilization height

    Energy Technology Data Exchange (ETDEWEB)

    Dyckes, G.W.

    1980-07-01

    A method of approximating the cloud stabilization height for aerosol-sized particles vented explosively through earth containment systems is presented. The calculated values for stabilization heights are in fair agreement with those obtained experimentally.

  2. Size-resolved morphological properties of the high Arctic summer aerosol during ASCOS-2008

    Science.gov (United States)

    Hamacher-Barth, Evelyne; Leck, Caroline; Jansson, Kjell

    2016-05-01

    The representation of aerosol properties and processes in climate models is fraught with large uncertainties. Especially at high northern latitudes a strong underprediction of aerosol concentrations and nucleation events is observed and can only be constrained by in situ observations based on the analysis of individual aerosol particles. To further reduce the uncertainties surrounding aerosol properties and their potential role as cloud condensation nuclei this study provides observational data resolved over size on morphological and chemical properties of aerosol particles collected in the summer high Arctic, north of 80° N. Aerosol particles were imaged with scanning and transmission electron microscopy and further evaluated with digital image analysis. In total, 3909 aerosol particles were imaged and categorized according to morphological similarities into three gross morphological groups: single particles, gel particles, and halo particles. Single particles were observed between 15 and 800 nm in diameter and represent the dominating type of particles (82 %). The majority of particles appeared to be marine gels with a broad Aitken mode peaking at 70 nm and accompanied by a minor fraction of ammonium (bi)sulfate with a maximum at 170 nm in number concentration. Gel particles (11 % of all particles) were observed between 45 and 800 nm with a maximum at 154 nm in diameter. Imaging with transmission electron microscopy allowed further morphological discrimination of gel particles in "aggregate" particles, "aggregate with film" particles, and "mucus-like" particles. Halo particles were observed above 75 nm and appeared to be ammonium (bi)sulfate (59 % of halo particles), gel matter (19 %), or decomposed gel matter (22 %), which were internally mixed with sulfuric acid, methane sulfonic acid, or ammonium (bi)sulfate with a maximum at 161 nm in diameter. Elemental dispersive X-ray spectroscopy analysis of individual particles revealed a prevalence of the monovalent

  3. Source and composition of size fractionated aerosols collected in the Central Valley

    Science.gov (United States)

    Allen, G.; Kelly, P. B.; Buchholz, B. A.; Clifford, A.

    2013-12-01

    The Central Valley in California has historically had high levels of atmospheric particulate matter (PM), resulting in significant adverse health effects. The three sources of atmospheric PM in the Central Valley are vehicle exhaust emissions, agricultural activity and residential wood burning. Ambient PM was collected during the winter of 2011 and 2012 in Davis, CA using a DRUM impact analyzer to determine the contributions of the various sources to the size fractionated aerosols. Laser desorption ionization time-of-flight mass spectrometry (LDI-TOF MS) and radiocarbon accelerator mass spectrometry (AMS) were performed on size fractionated atmospheric PM. The results show that as particle size decreases the amount of organic carbon increases. In the smallest size fraction (0.09 - 1.2 μm) the organic carbon encompasses approximately 70% of the LDI-TOF signal intensity. A comparison of the size fraction PM LDI-TOF spectra showed that there was a significant difference in the chemical composition with particle size. Three distinct chemical composition modes were observed in the LDI-TOF analysis: 0.09 to 0.34 μm, 0.34 to 0.56 μm and >0.56 μm. The particles 0.5 μm. The chemical difference in the PM is driven by the large amount of secondary organic aerosol. Dicarboxylic acids, aromatic acids and nitrated aromatics were predominately found in particles human health of these compounds needs to be further explored. The difference in the chemical composition between the respirable and larger PM needs to be considered when associating health effects with PM exposure. The radiocarbon AMS analysis showed that the size fractionated total carbonaceous particulate matter was mainly biogenic in origin, having an average fraction modern (F14C) = 0.753 × 0.006. The F14C from both sample collections were similar and there wasn't a significant change in fraction modern as particle size decreased. The high fraction modern in the small PM points to the secondary organic aerosol

  4. The Size Distribution of Casein Micelles in Camel Milk

    OpenAIRE

    Farah, Z.; Ruegg, M. W.

    1989-01-01

    The size distribution of casein micelles in camel milk has been determined by electron microscopy. Individual and pooled samples were cryo-fixed by rapid freezing and freeze-fractured. Electron micrographs of the freeze-fracture replica revealed a relatively broad size distribution, with an average micelle dimeter around 280 nm in the volume distribution curve. The distribution was significantly broader than that of the particles of cow's or human milk and showed a greater number of large ...

  5. 40 CFR Table F-5 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized “Typical” Coarse Aerosol Size...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Estimated Mass Concentration Measurement of PM2.5 for Idealized âTypicalâ Coarse Aerosol Size Distribution F Table F-5 to Subpart F of Part... of Class II Equivalent Methods for PM2.5 Pt. 53, Subpt. F, Table F-5 Table F-5 to Subpart F of...

  6. Optical-chemical-microphysical relationships and closure studies for mixed carbonaceous aerosols observed at Jeju Island; 3-laser photoacoustic spectrometer, particle sizing, and filter analysis

    OpenAIRE

    B. A. Flowers; Dubey, M.K.; C. Mazzoleni; Stone, E. A.; J. J. Schauer; Kim, S. -W.; Yoon, S.C.

    2010-01-01

    Transport of aerosols in pollution plumes from the mainland Asian continent was observed in situ at Jeju, South Korea during the Cheju Asian Brown Cloud Plume-Asian Monsoon Experiment (CAPMEX) field campaign throughout August and September 2008 using a 3-laser photoacoustic spectrometer (PASS-3), chemical filter analysis, and size distributions. The PASS-3 directly measures the effects of morphology (e.g. coatings) on light absorption that traditional filter-based instruments are unable to ad...

  7. Size-resolved aerosol water-soluble ionic compositions in the summer of Beijing: implication of regional secondary formation

    Directory of Open Access Journals (Sweden)

    Y. L. Zhao

    2009-11-01

    Full Text Available To characterize aerosol pollution in Beijing, size-resolved aerosols were collected by MOUDIs during CAREBEIJING-2006 field campaign at Peking University (urban site and Yufa (upwind rural site. Fine particle concentrations (PM1.8 by MOUDI were 99.8±77.4 μg/m3 and 78.2±58.4 μg/m3, with PM1.8/PM10 ratios of 0.64±0.08 and 0.76±0.08 at PKU and Yufa, respectively, and secondary compounds accounted for more than 50% in fine particles. PMF model was used to resolve the particle modes. Three modes were resolved at Yufa, representing condensation, droplet and coarse mode. However, one more droplet mode with bigger size was resolved, which was considered probably from regional transport. Condensation mode accounted for 10%–60% of the total mass at both sites, indicating it must be taken into account in summer. The formation of sulfate was mainly attributed to in-cloud or aerosol droplet process (PKU 80%, Yufa 70% and gas condensation process (PKU 14%, Yufa 22%. According to the thermodynamic instability of NH4NO3, size distributions of nitrate were classified as three categories by RH. The existence of Ca(NO32 in droplet mode indicated the reaction of HNO3 with crustal particles was also important in fine particles. Linear regression gave a rough estimation that 69% of the PM10 and 87% of the PM1.8 at PKU were regional contributions. Sulfate, ammonium and oxalate were formed regionally, with the regional contributions of 90%, 87% and 95% to PM1.8. Nitrate formation was local dominant. In summary regional secondary formation led to aerosol pollution in the summer of Beijing.

  8. Bimodal Size-distribution of Bainite Plates

    OpenAIRE

    Hase, K.; García Mateo, Carlos; Bhadeshia, H. K. D. H.

    2006-01-01

    There are two well-known phenomena associated with the bainite reaction, which have been exploited in the present work to enhance the mechanical behaviour of steel. Firstly, the bainite plate size decreases as the transformation temperature is reduced. Secondly, it is bad to have large regions of untransformed austenite in the microstructure; this is because they can transform, under the influence of external stress, into corresponding large regions of untempered, brittle martensite. By ad...

  9. The distribution of bubble sizes during reionization

    Science.gov (United States)

    Lin, Yin; Oh, S. Peng; Furlanetto, Steven R.; Sutter, P. M.

    2016-09-01

    A key physical quantity during reionization is the size of H II regions. Previous studies found a characteristic bubble size which increases rapidly during reionization, with apparent agreement between simulations and analytic excursion set theory. Using four different methods, we critically examine this claim. In particular, we introduce the use of the watershed algorithm - widely used for void finding in galaxy surveys - which we show to be an unbiased method with the lowest dispersion and best performance on Monte Carlo realizations of a known bubble size probability density function (PDF). We find that a friends-of-friends algorithm declares most of the ionized volume to be occupied by a network of volume-filling regions connected by narrow tunnels. For methods tuned to detect the volume-filling regions, previous apparent agreement between simulations and theory is spurious, and due to a failure to correctly account for the window function of measurement schemes. The discrepancy is already obvious from visual inspection. Instead, H II regions in simulations are significantly larger (by factors of 10-1000 in volume) than analytic predictions. The size PDF is narrower, and evolves more slowly with time, than predicted. It becomes more sharply peaked as reionization progresses. These effects are likely caused by bubble mergers, which are inadequately modelled by analytic theory. Our results have important consequences for high-redshift 21 cm observations, the mean free path of ionizing photons, and the visibility of Lyα emitters, and point to a fundamental failure in our understanding of the characteristic scales of the reionization process.

  10. The equilibrium size distribution of rouleaux.

    OpenAIRE

    Perelson, A. S.; Wiegel, F.W.

    1982-01-01

    Rouleaux are formed by the aggregation of red blood cells in the presence of macromolecules that bridge the membranes of adherent erythrocytes. We compute the size and degree of branching of rouleaux for macroscopic systems in thermal equilibrium in the absence of fluid flow. Using techniques from statistical mechanics, analytical expressions are derived for (a) the average number of rouleaux consisting of n cells and having m branch points; (b) the average number of cells per rouleau; (c) th...

  11. Mobility particle size spectrometers: harmonization of technical standards and data structure to facilitate high quality long-term observations of atmospheric particle number size distributions

    Directory of Open Access Journals (Sweden)

    A. Wiedensohler

    2012-03-01

    Full Text Available Mobility particle size spectrometers often referred to as DMPS (Differential Mobility Particle Sizers or SMPS (Scanning Mobility Particle Sizers have found a wide range of applications in atmospheric aerosol research. However, comparability of measurements conducted world-wide is hampered by lack of generally accepted technical standards and guidelines with respect to the instrumental set-up, measurement mode, data evaluation as well as quality control. Technical standards were developed for a minimum requirement of mobility size spectrometry to perform long-term atmospheric aerosol measurements. Technical recommendations include continuous monitoring of flow rates, temperature, pressure, and relative humidity for the sheath and sample air in the differential mobility analyzer.

    We compared commercial and custom-made inversion routines to calculate the particle number size distributions from the measured electrical mobility distribution. All inversion routines are comparable within few per cent uncertainty for a given set of raw data.

    Furthermore, this work summarizes the results from several instrument intercomparison workshops conducted within the European infrastructure project EUSAAR (European Supersites for Atmospheric Aerosol Research and ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network to determine present uncertainties especially of custom-built mobility particle size spectrometers. Under controlled laboratory conditions, the particle number size distributions from 20 to 200 nm determined by mobility particle size spectrometers of different design are within an uncertainty range of around ±10% after correcting internal particle losses, while below and above this size range the discrepancies increased. For particles larger than 200 nm, the uncertainty range increased to 30%, which could not be explained. The network reference mobility spectrometers with identical design agreed within ±4% in the

  12. 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.

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

    International Nuclear Information System (INIS)

    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

  14. Seasonal cycle and modal structure of particle number size distribution at Dome C, Antarctica

    Directory of Open Access Journals (Sweden)

    E. Järvinen

    2013-08-01

    Full Text Available We studied new particle formation and modal behavior of ultrafine aerosol particles on the high East Antarctic plateau at the Concordia station, Dome C (75°06' S, 123°23' E. Aerosol particle number size distributions were measured in the size range 10–600 nm from 14 December 2007 to 7 November 2009. We used an automatic algorithm for fitting up to three modes to the size distribution data. The total particle number concentration was low with the median of 109 cm−3. There was a clear seasonal cycle in the total particle number and the volume concentrations. The concentrations were at their highest during the austral summer with the median values of 260 cm−3 and 0.086 μm3 cm−3, and at their lowest during the austral winter with corresponding values of 15 cm−3 and 0.009 μm3 cm−3. New particle formation events were determined from the size distribution data. During the measurement period, natural new particle formation was observed on 60 days and for 15 of these days the particle growth rates from 10 to 25 nm in size could be determined. The median particle growth rate during all these events was 2.5 nm h−1 and the median formation rate of 10 nm particles was 0.023 cm−3 s−1. Most of the events were similar to those observed at other continental locations, yet also some variability in event types was observed. Exceptional features in Dome C were the winter events that occurred during dark periods, as well as the events for which the growth could be followed during several consecutive days. We called these latter events slowly growing events. This paper is the first one to analyze long-term size distribution data from Dome C, and also the first paper to show that new particle formation events occur in central Antarctica.

  15. The correlative method of industrial aerosol express-diagnostic

    International Nuclear Information System (INIS)

    The main difficulty of industrial aerosol control is absence of real-time data analysis methods for measurement quantities of a specific aerosol (for example, radioactive particles, beryllium aerosols, etc. This report is an attempt to establish a new experimental method for control of industrial aerosol pollution. The main idea of the method is to determine correlation dependences among the aerosol particle size distributions and quantities of specific aerosol particles in industrial pollutions, for which real-time control is very difficult. The possibility of specific aerosol control is suggested by means of aerosol size control. (author)

  16. The size distribution of inhabited planets

    Science.gov (United States)

    Simpson, Fergus

    2016-02-01

    Earth-like planets are expected to provide the greatest opportunity for the detection of life beyond the Solar system. However, our planet cannot be considered a fair sample, especially if intelligent life exists elsewhere. Just as a person's country of origin is a biased sample among countries, so too their planet of origin may be a biased sample among planets. The magnitude of this effect can be substantial: over 98 per cent of the world's population live in a country larger than the median. In the context of a simple model where the mean population density is invariant to planet size, we infer that a given inhabited planet (such as our nearest neighbour) has a radius r < 1.2r⊕ (95 per cent confidence bound). We show that this result is likely to hold not only for planets hosting advanced life, but also for those which harbour primitive life forms. Further, inferences may be drawn for any variable which influences population size. For example, since population density is widely observed to decline with increasing body mass, we conclude that most intelligent species are expected to exceed 300 kg.

  17. The size distribution of inhabited planets

    Science.gov (United States)

    Simpson, Fergus

    2016-02-01

    Earth-like planets are expected to provide the greatest opportunity for the detection of life beyond the Solar system. However, our planet cannot be considered a fair sample, especially if intelligent life exists elsewhere. Just as a person's country of origin is a biased sample among countries, so too their planet of origin may be a biased sample among planets. The magnitude of this effect can be substantial: over 98 per cent of the world's population live in a country larger than the median. In the context of a simple model where the mean population density is invariant to planet size, we infer that a given inhabited planet (such as our nearest neighbour) has a radius r planets hosting advanced life, but also for those which harbour primitive life forms. Further, inferences may be drawn for any variable which influences population size. For example, since population density is widely observed to decline with increasing body mass, we conclude that most intelligent species are expected to exceed 300 kg.

  18. Modelling of formation and distribution of secondary aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Andreani-Aksoyoglu, S.; Keller, J.; Baertsch-Ritter, N.; Prevot, A.S.H.; Dommen, J.; Baltensperger, U.

    2003-03-01

    The performance of aerosol modules of the 3-dimensional CAMx model was evaluated for the first time in a domain covering the Po Basin in northern Italy. The preliminary results for particulate species (especially those containing nitrate) smaller than 2.5 {mu}m were comparable to the values measured both in urban and rural stations. In most of the model domain, particulate NO{sub 3}{sup -} and NH{sub 4}{sup +} concentrations decreased with reduced NO{sub x} emissions. On the other hand, the levels of secondary organic carbon aerosols decreased with reduced VOC emissions, but increased with reduced NO{sub x} emissions similarly to ozone. Including aerosol chemistry in the model also affected the indicator values which are used for the ozone production sensitivities. (author)

  19. Aerosol distribution and efficacy in a commercial food warehouse

    Institute of Scientific and Technical Information of China (English)

    Frank H. Arthur

    2008-01-01

    A series of field trials were conducted in a commercial food storage facility to evaluate exposure of stored-product insects to aerosol formulations of synergized pyrethrins and the insect growth regulator methoprene. When adults of Tribolium castaneum (Herbst), the red flour beetle, and Tribolium confusum (Jacqueline DuVal), the confused flour beetle were exposed with and without a food source to synergized pyrethrin aerosol, there was no difference in adult mortality with respect to availability of food at either 7 or 14 days after exposure (P≥0.05). However, mortality was lower in T. confusum (40.4% and 79.3% with flour at 7 and 14 days, 38.9% and 84.8% without flour at 7 and 14 days) compared to T. castaneum (96.5% and 99.8% with flour at 7 and 14 days, 91.0% and 98.7% without flour at 7 and 14 days). Few late-stage larvae and pupae of either species exposed to the pyrethrin aerosol emerged as adults. In tests with methoprene aerosol, adult emergence of exposed 3- and 4-week-old larvae of T. confusum was less than 2%. Only 0.3% of 4-week-old larvae of T. castaneum exposed in open and obstructed areas emerged as adults. Emergence of adults from eggs of Plodia interpunctella (Huibner), the Indianmeal moth, embedded in culture media and exposed to the methoprene aerosol was 13.2% + 3.5%. Results show that the aerosols evaluated in our study could give effective control of some of the major storedproduct insect pests in commercial food storage facilities, and may offer an alternative to fumigation.

  20. Aerosol structure and vertical distribution in a multi-source dust region

    Institute of Scientific and Technical Information of China (English)

    Jie Zhang; Qiang Zhang; Congguo Tang; Yongxiang Han

    2012-01-01

    The vertical distribution of aerosols was directly observed under various atmospheric conditions in the free troposphere using surface micro-pulse lidar(MPLA)at the Zhangye Station(39.08°N,100.27°E)in western China in the spring of 2008.The study shows that the aerosol distribution over Zhangye can be vertically classified into upper,middle and lower layers with altitudes of 4.5 to 9 km,2.5 to 4.5 km,and less than 2.5 km,respectively.The aerosol in the upper layer originated from the external sources at higher altitude regions,from far desert regions upwind of Zhangye or transported from higher atmospheric layers by free convection,and the altitude of this aerosol layer decreased with time; the aerosols in the middle and lower layers originated from both external and local sources.The aerosol extinction coefficients in the upper and lower layers decreased with altitude,whereas the coefficient in the middle layer changed only slightly,which suggests that aerosol mixing occurs in the middle layer.The distribution of aerosols with altitude has three features:a single peak that forms under stable atmospheric conditions,an exponential decrease with altitude that occurs under unstable atmospheric conditions,and slight change in the mixed layer.Due to the impact of the top of the atmospheric boundary layer,the diurnal variation in the aerosol extinction coefficient has a single peak,which is higher in the afternoon and lower in the morning.

  1. Distributions of region size and GDP and their relation

    Science.gov (United States)

    Sen, Hu; Chunxia, Yang; Xueshuai, Zhu; Zhilai, Zheng; Ya, Cao

    2015-07-01

    We first analyze the distribution of metropolitan (city) size, the distribution of metropolitan (city) GDP and the relation of both distributions. It is found that (1) the tails of distributions of size and GDP both obey Pareto Law with the Pareto exponent 1; (2) compared with Pareto exponent in GDP, Pareto exponent in size is bigger. Then an agent model is built to study the underlying formation mechanism of distributions of region size and GDP. Our model presents the mechanism how economic factors flow between regions to reproduce the tail behavior and the difference between the Pareto exponents of size and those of GDP. At last, the simulated results agree with the real empirical well.

  2. Size-segregated compositional analysis of aerosol particles collected in the European Arctic during the ACCACIA campaign

    Science.gov (United States)

    Young, G.; Jones, H. M.; Darbyshire, E.; Baustian, K. J.; McQuaid, J. B.; Bower, K. N.; Connolly, P. J.; Gallagher, M. W.; Choularton, T. W.

    2016-03-01

    Single-particle compositional analysis of filter samples collected on board the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft is presented for six flights during the springtime Aerosol-Cloud Coupling and Climate Interactions in the Arctic (ACCACIA) campaign (March-April 2013). Scanning electron microscopy was utilised to derive size-segregated particle compositions and size distributions, and these were compared to corresponding data from wing-mounted optical particle counters. Reasonable agreement between the calculated number size distributions was found. Significant variability in composition was observed, with differing external and internal mixing identified, between air mass trajectory cases based on HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) analyses. Dominant particle classes were silicate-based dusts and sea salts, with particles notably rich in K and Ca detected in one case. Source regions varied from the Arctic Ocean and Greenland through to northern Russia and the European continent. Good agreement between the back trajectories was mirrored by comparable compositional trends between samples. Silicate dusts were identified in all cases, and the elemental composition of the dust was consistent for all samples except one. It is hypothesised that long-range, high-altitude transport was primarily responsible for this dust, with likely sources including the Asian arid regions.

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

    Directory of Open Access Journals (Sweden)

    T. Takemura

    2012-08-01

    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.

  4. 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.

  5. Size-Time-Composition Resolved Study of Aerosols Across El Paso, Texas in Fall 2008

    Science.gov (United States)

    Cahill, T. A.; Gill, T. E.; Pingitore, N. E.; Olvera, H. A.; Clague, J. W.; Barnes, D. E.; Perry, K. D.; Li, W.; Amaya, M. A.

    2009-12-01

    Systematic variations in the absolute amounts, size and composition of airborne particulate matter (PM) across the El Paso, Texas metropolitan area may differentially impact the respiratory status (e.g., asthma) and overall health of the local population. To understand these variations, we collected size-time resolved samples of PM with DRUM samplers during a one-month period in late autumn 2008 at three sites along a NW-SE (roughly upwind-downwind) transect across El Paso’s airshed. The DRUM sampler is a rotating-drum impactor separating and collecting aerosols on Mylar strips mounted on the drums, in 8 size stages from 10 μm to ~1 μm. Calcium/silicon ratios were high (>1), especially in coarser stages and during high wind events, reflecting wind erosion of the Chihuahuan Desert’s calcareous soils. Concentrations of chlorine, silicon, calcium, coarse potassium, and lead increased during high wind events, while fine chlorine and fine potassium increased during smoke events, and zinc, sulfur, and fine potassium concentrations increased during inversion/stagnation events. Concentrations of most elements, especially crustal elements, increased overall from Santa Teresa to UTEP to Socorro, reflecting generation and downwind transport of fugitive dust from the urban area. The Santa Teresa site, located almost always upwind of the metropolitan area and physically above the inversions, showed generally much lower concentrations of aerosols than the other two sites. The Socorro site had more frequent aerosol events, likely associated with down-valley drainage flows and downwind transport of particulates from El Paso and the larger city of Ciudad Juarez, Chihuahua, Mexico, immediately across the Rio Grande. (This project was supported by grant number 1 S11 ES013339-01A1 from the National Institute of Environmental Health Sciences (NIEHS), NIH. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS

  6. Combustion characteristics of water-insoluble elemental and organic carbon in size selected ambient aerosol particles

    Directory of Open Access Journals (Sweden)

    K. Wittmaack

    2005-04-01

    Full Text Available Combustion of elemental carbon (EC and organic carbon (OC contained in ambient aerosol matter was explored using scanning electron microscopy (SEM in combination with energy dispersive X-ray analysis (EDX. To ease identification of the particles of interest and to avoid or at least reduce interaction with simultaneously sampled inorganic oxides and salts, the approach used in this work differed in two ways from commonly applied procedures. First, rather than using a mixture of particles of vastly different sizes, as in PM10 or PM2.5, aerosol matter was collected in a 5-stage impactor. Second, the water soluble fraction of the collected matter was removed prior to analysis. Diesel soot particles, which appeared in the well-known form of chain-type aggregates, constituted the major fraction of EC. In contrast, OC containing particles were observed in a variety of shapes, including a sizable amount of bioaerosol matter appearing mostly in the size range above about 1 µm. During heating in ambient air for 1 h, diesel soot particles were found to be stable up to 480°C, but complete combustion occurred in a narrow temperature interval between about 490 and 510°C. After diesel soot combustion, minute quantities of ''ash'' were observed in the form of aggregated tiny particles with sizes less than 10 nm. These particles could be due to elemental or oxidic contaminants of diesel soot. Combustion of OC was observed over a wide range of temperatures, from well below 200°C to at least 500°C. Incompletely burnt bioaerosol matter was still found after heating to 600°C. The results imply that the EC fraction in aerosol matter can be overestimated significantly if the contribution of OC to a thermogram is not well separated.

  7. Combustion characteristics of water-insoluble elemental and organic carbon in size selected ambient aerosol particles

    Directory of Open Access Journals (Sweden)

    K. Wittmaack

    2005-01-01

    Full Text Available Combustion of elemental carbon (EC and organic carbon (OC contained in ambient aerosol matter was explored using scanning electron microscopy (SEM in combination with energy dispersive X-ray analysis (EDX. To ease identification of the particles of interest and to avoid or at least reduce interaction with simultaneously sampled inorganic oxides and salts, the approach used in this work differed in two ways from commonly applied procedures. First, rather than using a mixture of particles of vastly different sizes, as in PM10 or PM2.5, aerosol matter was collected in a 5-stage impactor. Second, the water soluble fraction of the collected matter was removed prior to analysis. Diesel soot particles, which appeared in the well-known form of chain-type aggregates, constituted the major fraction of EC. In contrast, OC containing particles were observed in a variety of shapes, including a sizable amount of bioaerosol matter appearing mostly in the size range above about 1 µm. During heating in ambient air for 1h, diesel soot particles were found to be stable up to 470°C, but complete combustion occurred in a narrow temperature interval between about 480 and 510°C. After diesel soot combustion, minute quantities of 'ash' were observed in the form of aggregated tiny particles with sizes less than 10 nm. These particles could be due to elemental or oxidic contaminants of diesel soot. Combustion of OC was observed over a wide range of temperatures, from well below 200°C to at least 500°C. Incompletely burnt bioaerosol matter was still found after heating to 600°C. The results imply that the EC fraction in aerosol matter can be overestimated significantly if the contribution of OC to a thermogram is not well separated.

  8. Stratospheric aerosols

    International Nuclear Information System (INIS)

    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

  9. A pseudo-Lagrangian model study of the size distribution properties over Scandinavia: transport from Aspvreten to Värriö

    Directory of Open Access Journals (Sweden)

    P. Tunved

    2004-11-01

    Full Text Available The evolution of the aerosol size distribution during transport between Aspvreten (58.8° N, 17.4° E and Värriö (67.46° N, 29.35° E was studied using a pseudo-Lagrangian approach. Aerosol dynamic processes were studied and interpreted utilizing a state-of-the-art aerosol dynamic box model UHMA (University of Helsinki Multicomponent Aerosol model complemented with OH, NO3, O3 and terpene chemistry. In the model simulations, the growth and formation of aerosol particles was controlled by sulphuric acid, ammonia, water and an unidentified low volatile organic compound. This organic compound was assumed to be a product of terpene oxidation with a yield of 13% in the base case conditions.

    Changes of aerosol size distribution properties during transport between the stations were examined in twelve clear sky cases. On average, the modelled number agreed fairly well with observations. Mass concentration was overestimated by 10%.

    Apart from dilution, the only removal mechanism for aerosol mass is dry deposition. A series of sensitivity tests performed revealed that the absolute magnitude of dry deposition effects on the aerosol size distribution is slow overall. Furthermore, nucleation does not leave a significant contribution to aerosol number in the selected cases. The sensitivity of the modelled size distribution to concentration of precursor gases and oxidants is, however, obvious. In order to explain observed mass increase during transport we conclude that a yield of low volatile products from oxidation of terpenes of 10–15% is required to explain observed growth rates. Coagulation is acknowledged to be highly important in modelled cases.

  10. Sensitivity of aerosol concentrations and cloud properties to nucleation and secondary organic distribution in ECHAM5-HAM global circulation model

    Directory of Open Access Journals (Sweden)

    R. Makkonen

    2009-03-01

    Full Text Available The global aerosol-climate model ECHAM5-HAM was modified to improve the representation of new particle formation in the boundary layer. Activation-type nucleation mechanism was introduced to produce observed nucleation rates in the lower troposphere. A simple and computationally efficient model for biogenic secondary organic aerosol (BSOA formation was implemented. Here we study the sensitivity of the aerosol and cloud droplet number concentrations (CDNC to these additions. Activation-type nucleation significantly increases aerosol number concentrations in the boundary layer. Increased particle number concentrations have a significant effect also on cloud droplet number concentrations and therefore on cloud properties. We performed calculations with activation nucleation coefficient values of 2×10−7s−1, 2×10−6s−1 and 2×10−5s−1 to evaluate the sensitivity to this parameter. For BSOA we have used yields of 0.025, 0.07 and 0.15 to estimate the amount of monoterpene oxidation products available for condensation. The hybrid BSOA formation scheme induces large regional changes to size distribution of organic carbon, and therefore affects particle optical properties and cloud droplet number concentrations locally. Although activation-type nucleation improves modeled aerosol number concentrations in the boundary layer, the use of a global activation coefficient generally leads to overestimation of aerosol number. Overestimation can also arise from underestimation of primary emissions.

  11. Experimental determination of submicron aerosol dry deposition velocity onto rural canopies: influence of aerosol size, of micro meteorological parameters and of the substrate

    International Nuclear Information System (INIS)

    To evaluate the impact of accidental or chronic pollutant releases on ecosystems, we must study the dry deposition of aerosols in rural areas. The lack of experimental data on the dry deposition velocity of particle sizes below 1 μm over rural environments leads to uncertainties regarding models and differences between them, which exceed one order of magnitude. The aim of this study is to develop a method, especially using an Electrical Low Pressure Impactor (Outdoor ELPIDEKATI) to determine aerosol dry deposition velocities (Vd) over rural areas through experimental measurements. This method is based on eddy covariance flux calculation and spectral analysis correction. Dry deposition velocities were obtained for atmospheric aerosols sizing from 7 nm to 2 μm, in the South-West of France on a flat terrain under varied meteorological conditions and varied substrates (maize, grass and earth). Vd was analysed as a function of the particle diameters, and the impact of micro meteorological parameters was studied. (author)

  12. Chamber bioaerosol study: human emissions of size-resolved fluorescent biological aerosol particles

    OpenAIRE

    Bhangar, Seema; Adams, Rachel I.; Pasut, Wilmer; Huffman, Alex; Arens, Edward A.; Taylor, John W; Bruns, Tom D; Nazaroff, William W

    2015-01-01

    Humans are a prominent source of airborne biological particles in occupied indoor spaces, but few studies have quantified human bioaerosol emissions. The chamber investigation reported here employs a fluorescence-based technique to evaluate bioaerosols with high temporal and particle size resolution. In a 75-m3 chamber, occupant emission rates of coarse (2.5–10 μm) fluorescent biological aerosol particles (FBAPs) under seated, simulated office-work conditions averaged 0.9 ± 0.3 million partic...

  13. Size Dependence of Reactive Uptake Coefficient in Chemical Reactions on Aerosol Nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Levdansky, Valerij Vladimirovič; Smolík, Jiří; Ždímal, Vladimír; Moravec, Pavel

    Praha : Česká aerosolová společnost, 2012 - (Vodička, P.; Zíková, N.), s. 77-78 ISBN 978-80-86186-40-5. [Výroční konference České aerosolové společnosti /13./. Třeboň (CZ), 25.10.2012-26.10.2012] R&D Projects: GA ČR GA101/09/1633; GA AV ČR IAA200760905 Institutional support: RVO:67985858 Keywords : reactive uptake coefficient * size effect * nanoscale aerosol particles Subject RIV: CF - Physical ; Theoretical Chemistry

  14. Anthropogenic aerosols and the distribution of past large-scale precipitation change

    Science.gov (United States)

    Wang, Chien

    2015-12-01

    The climate response of precipitation to the effects of anthropogenic aerosols is a critical while not yet fully understood aspect in climate science. Results of selected models that participated the Coupled Model Intercomparison Project Phase 5 and the data from the Twentieth Century Reanalysis Project suggest that, throughout the tropics and also in the extratropical Northern Hemisphere, aerosols have largely dominated the distribution of precipitation changes in reference to the preindustrial era in the second half of the last century. Aerosol-induced cooling has offset some of the warming caused by the greenhouse gases from the tropics to the Arctic and thus formed the gradients of surface temperature anomaly that enable the revealed precipitation change patterns to occur. Improved representation of aerosol-cloud interaction has been demonstrated as the key factor for models to reproduce consistent distributions of past precipitation change with the reanalysis data.

  15. Estimating neutral nanoparticle steady state size distribution and growth according to measurements of intermediate air ions

    Directory of Open Access Journals (Sweden)

    H. Tammet

    2013-05-01

    Full Text Available The concentration of nanometer aerosol particles in atmospheric air during quiet periods of new particle formation is low and direct measuring is difficult. We study what information about neutral particles can be drawn from measurements of intermediate ions, which are the electrically charged particles between 1.5–7.5 nm in diameter. If the coagulation sink of nanoparticles and the growth rate of charged particles are known, then the steady state equations allow us to calculate the size distribution of neutral nanoparticles. Variations in the trial value of the growth rate have a minor effect on the estimates of the concentrations and size distributions. There exists a value of the constant growth rate of charged nanoparticles that leads to a minimum deviation of the estimated growth rate of neutral nanoparticles from the growth rate of charged nanoparticles. Rough estimates of the growth rate and size distribution of neutral nanoparticles are derived despite the fact that the sample data of intermediate ion measurements is not accompanied by simultaneous measurements of the background aerosol and ionization rate. In the case of a near-median intermediate ion concentration of 21 ± 2 cm−3 in the urban air of a small town, the growth rate of nanoparticles is estimated to be about 2 nm h−1, while the growth flux or apparent nucleation rate is about 0.5 cm−3 s−1 at 3 nm and about 0.08 cm−3 s−1 at 7 nm. The results suggest that the process of new particle formation is not interrupted during the quiet periods between events of intensive nucleation of atmospheric aerosols.

  16. Estimating neutral nanoparticle steady state size distribution and growth according to measurements of intermediate air ions

    Science.gov (United States)

    Tammet, H.; Komsaare, K.; Hõrrak, U.

    2013-05-01

    The concentration of nanometer aerosol particles in atmospheric air during quiet periods of new particle formation is low and direct measuring is difficult. We study what information about neutral particles can be drawn from measurements of intermediate ions, which are the electrically charged particles between 1.5-7.5 nm in diameter. If the coagulation sink of nanoparticles and the growth rate of charged particles are known, then the steady state equations allow us to calculate the size distribution of neutral nanoparticles. Variations in the trial value of the growth rate have a minor effect on the estimates of the concentrations and size distributions. There exists a value of the constant growth rate of charged nanoparticles that leads to a minimum deviation of the estimated growth rate of neutral nanoparticles from the growth rate of charged nanoparticles. Rough estimates of the growth rate and size distribution of neutral nanoparticles are derived despite the fact that the sample data of intermediate ion measurements is not accompanied by simultaneous measurements of the background aerosol and ionization rate. In the case of a near-median intermediate ion concentration of 21 ± 2 cm-3 in the urban air of a small town, the growth rate of nanoparticles is estimated to be about 2 nm h-1, while the growth flux or apparent nucleation rate is about 0.5 cm-3 s-1 at 3 nm and about 0.08 cm-3 s-1 at 7 nm. The results suggest that the process of new particle formation is not interrupted during the quiet periods between events of intensive nucleation of atmospheric aerosols.

  17. Source contributions to the size and composition distribution of urban particulate air pollution

    Science.gov (United States)

    Kleeman, Michael J.; Cass, Glen R.

    A mechanistic air quality model has been constructed which is capable of predicting the contribution of individual emissions source types to the size- and chemical-composition distribution of airborne particles. This model incorporates all of the major aerosol processes relevant to regional air pollution studies including emissions, transport, deposition, gas-to-particle conversion and fog chemistry. In addition, the aerosol is represented as a source-oriented external mixture which is allowed to age in a more realistic fashion than can be accomplished when fresh particle-phase emissions are averaged into the pre-existing atmospheric aerosol size and composition distribution. A source-oriented external mixture is created by differentiating the primary particles emitted from the following source types: catalyst-equipped gasoline engines, non-catalyst-equipped gasoline engines, diesel engines, meat cooking, paved road dust, crustal material from sources other than paved road dust, and sulfur-bearing particles from fuel burning and industrial processes. Discrete primary seed particles from each of these source types are emitted into a simulation of atmospheric transport and chemical reaction. The individual particles evolve over time in the presence of gas-to-particle conversion processes while retaining information on the initial source from which they were emitted. The source- and age-resolved particle mechanics model is applied to the 1987 August SCAQS episode and comparisons are made between model predictions and observations at Claremont, CA. The model explains the origin of the bimodal character of the sub-micron aerosol size distribution. The mode located between 0.2 and 0.3 μm particle diameter is shaped by transformed emissions from diesel engines and meat cooking operations with lesser contributions from gasolinepowered vehicles and other fuel burning. The larger mode located at 0.7-0.8 μm particle diameter is due to fine particle background aerosol that

  18. Airborne DOAS measurements in Arctic: vertical distributions of aerosol