scholarly journals Size distributions of non-volatile particle residuals (D<sub><i>p</i></sub><800 nm) at a rural site in Germany and relation to air mass origin

2006 ◽  
Vol 6 (3) ◽  
pp. 5505-5542 ◽  
Author(s):  
C. Engler ◽  
D. Rose ◽  
B. Wehner ◽  
A. Wiedensohler ◽  
E. Brüggemann ◽  
...  
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Elemental Carbon ◽  
Size Range ◽  
Rural Site ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Air Mass ◽  
Air Masses ◽  
Volatile Particle

Abstract. Atmospheric aerosol particle size distributions at a continental background site in Eastern Germany were examined for a one-year period. Particles were classified using a twin differential mobility particle sizer in a size range between 3 and 800 nm. As a novelty, every second measurement of this experiment involved the removal of volatile chemical compounds in a thermodenuder at 300°C. This concept allowed to quantify the number size distribution of non-volatile particle cores – primarily associated with elemental carbon, and to compare this to the original ambient size distribution. A general result was that practically every ambient particle in continental background air contained a non-volatile core. The volume fraction of non-volatile particulate matter (ambient Dp<800 nm) varied between 10 and 30% and was largely consistent with the experimentally determined mass fraction of elemental carbon. The average size of the non-volatile particle cores was estimated as a function of original ambient size using a summation method, which showed that larger particles (>200 nm) contained more non-volatile compounds than smaller particles (<50 nm), thus indicating a significantly different chemical composition. Two alternative air mass classification schemes based on either, synoptic chart analysis (Berliner Wetterkarte) or back trajectories showed, that the volume and number fractions of non-volatile cores were less dependent on air mass than the absolute concentrations in the particle size distributions. In all air masses, the non-volatile size distributions showed a more and a less volatile ("soot") mode, which is located in the size range of about 50 nm. During unstable conditions and in maritime air masses, smaller values were observed compared to continental or stable conditions. This reflects the significant emissions of non-volatile material over the continent and, depending on atmospheric stratification, increased concentrations at ground level.

scholarly journals Size distributions of non-volatile particle residuals (D<sub>p</sub><800 nm) at a rural site in Germany and relation to air mass origin

2007 ◽  
Vol 7 (22) ◽  
pp. 5785-5802 ◽  
Author(s):  
C. Engler ◽  
D. Rose ◽  
B. Wehner ◽  
A. Wiedensohler ◽  
E. Brüggemann ◽  
...  
Keyword(s):  
Size Distribution ◽  
Elemental Carbon ◽  
Volume Fraction ◽  
Summation Method ◽  
Rural Site ◽  
Size Distributions ◽  
Air Mass ◽  
Back Trajectories ◽  
Air Masses ◽  
Volatile Particle

Abstract. Atmospheric aerosol particle size distributions at a continental background site in Eastern Germany were examined for a one-year period. Particles were classified using a twin differential mobility particle sizer in a size range between 3 and 800 nm. As a novelty, every second measurement of this experiment involved the removal of volatile chemical compounds in a thermodenuder at 300°C. This concept allowed to quantify the number size distribution of non-volatile particle cores – primarily associated with elemental carbon, and to compare this to the original non-conditioned size distribution. As a byproduct of the volatility analysis, new particles originating from nucleation inside the thermodenuder can be observed, however, overwhelmingly at diameters below 6 nm. Within the measurement uncertainty, every particle down to particle sizes of 15 nm is concluded to contain a non-volatile core. The volume fraction of non-volatile particulate matter (non-conditioned diameter < 800 nm) varied between 10 and 30% and was largely consistent with the experimentally determined mass fraction of elemental carbon. The average size of the non-volatile particle cores was estimated as a function of original non-conditioned size using a summation method, which showed that larger particles (>200 nm) contained more non-volatile compounds than smaller particles (<50 nm), thus indicating a significantly different chemical composition. Two alternative air mass classification schemes based on either, synoptic chart analysis (Berliner Wetterkarte) or back trajectories showed that the volume and number fraction of non-volatile cores depended less on air mass than the total particle number concentration. In all air masses, the non-volatile size distributions showed a more and a less volatile ("soot") mode, the latter being located at about 50 nm. During unstable conditions and in maritime air masses, smaller values were observed compared to stable or continental conditions. This reflects the significant emission of non-volatile material over the continent and, depending on atmospheric stratification, increased concentrations at ground level.

Transport Methods of Determining Particle Size Distributions in Colloidal Systems

1981 ◽  
Vol 54 (4) ◽  
pp. 882-891 ◽  
Author(s):  
C. D. Shuster ◽  
J. R. Schroeder ◽  
D. McIntyre
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Size Range ◽  
Size Distributions ◽  
Rotor Speed ◽  
Colloidal Systems ◽  
Particle Size Distributions ◽  
Density Distributions ◽  
Yield Information

Abstract The two techniques examined in this work yield information about the particle size distribution of the latexes studied. The ease of measurement is improved over previous methods used on broadly distributed latexes. The TPC curves for both the natural and synthetic latexes correlate with the centrifuge curves. Both techniques show the Hevea to have larger particles than the guayule. The techniques also show SBR latex samples 1 and 2 to have larger particles than samples 3 and 4. The TPC is useful only for particles between 0.3 µm and 20 µm in size. The centrifuge can be used for any size range of particles by altering the rotor speed or eluant density. By employing the proper mathematics, these data could be easily converted from optical density distributions to particle size distributions.

The Occurrence of Particle Size Distribution Bimodality in Midlatitude Cirrus as Inferred from Ground-Based Remote Sensing Data

2011 ◽  
Vol 68 (6) ◽  
pp. 1162-1177 ◽  
Author(s):  
Yang Zhao ◽  
Gerald G. Mace ◽  
Jennifer M. Comstock
Keyword(s):  
Remote Sensing ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Size Range ◽  
Remote Sensing Data ◽  
General Nature ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Sensing Data

Abstract Data collected in midlatitude cirrus clouds by instruments on jet aircraft typically show particle size distributions that have distinct distribution modes in both the 10–30-μm maximum dimension (D) size range and the 200–300-μm D size range or larger. A literal interpretation of the small D mode in these datasets suggests that total concentrations Nt in midlatitude cirrus are, on average, well in excess of 1 cm−3 whereas more conventional analyses of in situ data and cloud process model results suggest Nt values a factor of 10 less. Given this wide discrepancy, questions have been raised regarding the influence of data artifacts caused by the shattering of large crystals on aircraft and probe surfaces. This inconsistency and the general nature of the cirrus particle size distribution are examined using a ground-based remote sensing dataset. An algorithm using millimeter-wavelength radar Doppler moments and Raman lidar-derived extinction is developed to retrieve a bimodal particle size distribution and its uncertainty. This algorithm is applied to case studies as well as to 313 h of cirrus measurements collected at the Atmospheric Radiation Measurement site near Lamont, Oklahoma, in 2000. It is shown that particle size distributions in cirrus can often be described as bimodal, and that this bimodality is a function of temperature and location within cirrus layers. However, the existence of Nt &gt; 1 cm−3 in cirrus is rare (&lt;1% of the time) and the Nt implied by the remote sensing data tends to be on the order of 100 cm−3.

scholarly journals Particle size distributions in the Eastern Mediterranean troposphere

2008 ◽  
Vol 8 (22) ◽  
pp. 6729-6738 ◽  
Author(s):  
N. Kalivitis ◽  
W. Birmili ◽  
M. Stock ◽  
B. Wehner ◽  
A. Massling ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Particle Size ◽  
Eastern Mediterranean ◽  
Particle Formation ◽  
Particle Nucleation ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Air Masses ◽  
Crete Island ◽  
Particle Sizer

Abstract. 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.

scholarly journals Particle size distributions in the Eastern Mediterranean troposphere

2008 ◽  
Vol 8 (2) ◽  
pp. 6571-6601
Author(s):  
N. Kalivitis ◽  
W. Birmili ◽  
M. Stock ◽  
B. Wehner ◽  
A. Massling ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Particle Size ◽  
Eastern Mediterranean ◽  
Particle Formation ◽  
Particle Nucleation ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Air Masses ◽  
Crete Island ◽  
Particle Sizer

Abstract. 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.

The moment ratios of particle size distributions in some simple growth models

1980 ◽  
Vol 17 (4) ◽  
pp. 956-967 ◽  
Author(s):  
H. L. MacGillivray
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Growth Model ◽  
Hazard Rate ◽  
Growth Models ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Initial Size ◽  
The Moment ◽  
Simple Growth

Important parameters of particle size distributions in dispersed systems in engineering and related fields are ratios of moments and inverse powers of these ratios, known as mean sizes. The variation in these parameters is examined for the simplest growth model in which the size distribution is translated, and the results for this process considered in relation to the problems of models of other growth processes. For initial size distributions with monotone hazard rate, the results are particularly significant, and the properties of the normalised moments of other distributions are also considered.

scholarly journals Spatial and Seasonal Variations of PM Concentration and Size Distribution in Manure-Belt Poultry Layer Houses

2019 ◽  
Vol 62 (2) ◽  
pp. 415-427 ◽  
Author(s):  
Reyna M. Knight ◽  
Xinjie Tong ◽  
Zhenyu Liu ◽  
Sewoon Hong ◽  
Lingying Zhao
Keyword(s):  
Particle Size ◽  
Particulate Matter ◽  
Size Distribution ◽  
Seasonal Variations ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Potential Health ◽  
Significant Difference ◽  
Autumn And Winter ◽  
Mass Concentrations

Abstract. Poultry layer houses are a significant source of particulate matter (PM) emissions, which potentially affect worker and animal health. Particulate matter characteristics, such as concentration and size distribution inside layer houses, are critical information for assessment of the potential health risks and development of effective PM mitigation technologies. However, this information and its spatial and seasonal variations are lacking for typical layer facilities. In this study, two TSI DustTrak monitors (DRX 8533) and an Aerodynamic Particle Sizer (APS 3321) were used to measure PM mass concentrations and number-weighted particle size distributions in two typical manure-belt poultry layer houses in Ohio in three seasons: summer, autumn, and winter. Bimodal particle size distributions were consistently observed. The average count median diameters (mean ±SD) were 1.68 ±0.25, 2.16 ±0.31, and 1.87 ±0.07 µm in summer, autumn, and winter, respectively. The average geometric standard deviations of particle size were 2.16 ±0.23, 2.16 ±0.18, and 1.74 ±0.17 in the three seasons, respectively. The average mass concentrations were 67.4 ±54.9, 289.9 ±216.2, and 428.1 ±269.9 µg m-3 for PM2.5; 73.6 ±59.5, 314.6 ±228.9, and 480.8 ±306.5 µg m-3 for PM4; and 118.8 ±99.6, 532.5 ±353.0, and 686.2 ±417.7 µg m-3 for PM10 in the three seasons, respectively. Both statistically significant (p &lt; 0.05) and practically significant (difference of means &gt;20% of smaller value) seasonal variations were observed. Spatial variations were only practically significant for autumn mass concentrations, likely due to external dust infiltration from nearby agricultural activities. The OSHA-mandated permissible exposure limit for respirable PM was not exceeded in any season. Keywords: Air quality, Particulate matter, Poultry housing, Seasonal variation, Spatial variation.

Characterization of Particle Size, Number, and Mass Emissions From a Diesel Powered Generator

2006 ◽  
Author(s):  
Imad A. Khalek
Keyword(s):  
Particle Size ◽  
Solid Particle ◽  
Particle Distribution ◽  
Size Range ◽  
Number Concentration ◽  
Solid Particles ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Engine Operation ◽  
Size Number

Total (volatile plus solid) and solid particle size, number, and mass emitted from a 3.8 kW diesel powered generator were characterized using a Scanning Mobility Particle Sizer (SMPS) that measures the size distribution of particles, and a catalytic stripper that facilitates the measurement of solid particles. The engine was operated at a constant speed for six steady-state engine operations ranging from idle to rated power. The solid particle size distributions were mainly monomodal lognormal distributions in nature reflecting a typical soot agglomerate size distribution with a number mean diameter in the size range from 98 nm to 37 nm as the load decreases from high to low. At idle, M6, however, the solid particle distribution was bimodal in nature with a high number of solid nanoparticles in the sub-20 nm size range. It is likely that these solid particles nucleated later in the combustion process from metallic ash typically present in the lube oil. The total particle size distributions exhibited a bimodal structure only at light load, M5, engine operation, where a high number of volatile nanoparticles were observed. The rest of the operating conditions exhibited monomodal distributions although the nature of the particles was vastly different. For the medium load modes, M2, M3, and M4, the particles were mainly solid particles. For the rated power, M1, and idle, M6, modes of engine operation, significant number of volatile particles grew to a size nearing that of soot particles making the distribution monomodal, similar to that of a solid particle distribution. This shows that monomodal distributions are not necessarily solid particle but they can be strongly dominated with volatile particles if significant particle growth takes place like the case at M1, and M6. The total number and mass concentration were extremely high at engine rated power. The number concentration exceeded 1.2 billion particles per cubic centimeter and the mass exceeded 750 milligrams per cubic meter. The number concentration is more than five orders of magnitude higher than a typical ambient level concentration, and the mass concentration is more than four orders of magnitude higher. It is important to indicate, however, that if the engine power rating is lowered by 35 percent from its designated level, both particle mass and number emissions will be reduced by two orders of magnitude. By measuring total and solid particle size and number concentration of particles, one can calculate other metrics such as surface area and mass to provide detail information about particle emissions. Such information can serve as an important database where all metrics of particle emissions are captured.

scholarly journals Fast time response measurements of particle size distributions in the 3–60 nm size range with the nucleation mode aerosol size spectrometer

2018 ◽  
Vol 11 (6) ◽  
pp. 3491-3509 ◽  
Author(s):  
Christina Williamson ◽  
Agnieszka Kupc ◽  
James Wilson ◽  
David W. Gesler ◽  
J. Michael Reeves ◽  
...  
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Cloud Condensation Nuclei ◽  
Radiation Budget ◽  
Fast Time ◽  
Size Distributions ◽  
Free Troposphere ◽  
Particle Size Distributions ◽  
Nucleation Mode ◽  
Data Inversion

Abstract. Earth's radiation budget is affected by new particle formation (NPF) and the growth of these nanometre-scale particles to larger sizes where they can directly scatter light or act as cloud condensation nuclei (CCN). Large uncertainties remain in the magnitude and spatiotemporal distribution of nucleation (less than 10 nm diameter) and Aitken (10–60 nm diameter) mode particles. Acquiring size-distribution measurements of these particles over large regions of the free troposphere is most easily accomplished with research aircraft. We report on the design and performance of an airborne instrument, the nucleation mode aerosol size spectrometer (NMASS), which provides size-selected aerosol concentration measurements that can be differenced to identify aerosol properties and processes or inverted to obtain a full size distribution between 3 and 60 nm. By maintaining constant downstream pressure the instrument operates reliably over a large range of ambient pressures and during rapid changes in altitude, making it ideal for aircraft measurements from the boundary layer to the stratosphere. We describe the modifications, operating principles, extensive calibrations, and laboratory and in-flight performance of two NMASS instruments operated in parallel as a 10-channel battery of condensation particle counters (CPCs) in the NASA Atmospheric Tomography Mission (ATom) to investigate NPF and growth to cloud-active sizes in the remote free troposphere. An inversion technique to obtain size distributions from the discrete concentrations of each NMASS channel is described and evaluated. Concentrations measured by the two NMASS instruments flying in parallel are self-consistent and also consistent with measurements made with an optical particle counter. Extensive laboratory calibrations with a range of particle sizes and compositions show repeatability of the response function of the instrument to within 5–8 % and no sensitivity in sizing performance to particle composition. Particle number, surface area, and volume concentrations from the data inversion are determined to better than 20 % for typical particle size distributions. The excellent performance of the NMASS systems provides a strong analytical foundation to explore NPF around the globe in the ATom dataset.

Determination of Particle Size Distribution of Nano-TiO2 Coating Film by AFM and Image Analysis

2010 ◽  
Vol 177 ◽  
pp. 22-24
Author(s):  
Zheng Min Li ◽  
Zhi Wei Chen ◽  
Min Tan ◽  
Ke Jing Xu ◽  
Bing Jiang
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Coating Film ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Nano Tio2 ◽  
Tio2 Particles ◽  
Atom Force Microscope

Nano-TiO2 coating film is one of the efficient photocatalysts. The particle size distribution of TiO2 has important influence on photocatalytic activity. A new method to determine the particle size distribution of TiO2 nano-film coated on ceramic was developed, by which the images of film acquired by Atom force microscope (AFM) were processed, and TiO2 particles contacted with others were separated and detected. The particle size distributions of two TiO2 nano-films were determined.

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