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.

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.

Phase and Particle Size Analysis of SnO2 Nanomaterials

2015 ◽  
Vol 1109 ◽  
pp. 314-318
Author(s):  
Nor Diyana Abdul Aziz ◽  
Kelimah Elong ◽  
Norlida Kamarulzaman
Keyword(s):  
Particle Size ◽  
Particle Size Analysis ◽  
Annealed Sample ◽  
Degree Of Crystallinity ◽  
Size Analysis ◽  
Size Distributions ◽  
X Ray Diffraction ◽  
Particle Size Distributions ◽  
X Ray ◽  
Particle Sizer

Tin Oxide (SnO2) is a metal oxide which has many applications in industry. In this study, SnO2 powders were synthesized by a self-propagating combustion (SPC) method. The product was annealed at 800 °C for 12 and 24 h before characterizing with X-Ray Diffraction (XRD) for phase studies. X-Ray Diffraction results showed that both samples are pure of tetragonal structure with space group P42/mnm. The sample annealed at a longer period, that is, 24 h, shows a higher degree of crystallinity compared to the 12 h annealed sample. It also shows a smaller full width at half maximum (FWHM), indicating larger crystallite size for the 24 h annealed sample. The particle size analysis reveals that there are two groups of particle size distributions for both samples. SEM results give values that are different from the particle sizer results due to the different nature of the measurement methods.

Modelling particle size distributions and secondary particle formation in emulsion polymerisation

Polymer ◽  
1998 ◽  
Vol 39 (26) ◽  
pp. 7099-7112 ◽  
Author(s):  
Emma M. Coen ◽  
Robert G. Gilbert ◽  
Bradley R. Morrison ◽  
Hartmann Leube ◽  
Sarah Peach
Keyword(s):  
Particle Size ◽  
Secondary Particle ◽  
Particle Formation ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Emulsion Polymerisation

scholarly journals Measurement report: Vertical profiling of particle size distributions over Lhasa, Tibet: Tethered balloon-based in-situ measurements and source apportionment

2021 ◽  
Author(s):  
Liang Ran ◽  
Zhaoze Deng ◽  
Yunfei Wu ◽  
Jiwei Li ◽  
Zhixuan Bai ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Particle Size ◽  
Source Apportionment ◽  
Particle Mass ◽  
Size Distributions ◽  
Aerosol Formation ◽  
Tethered Balloon ◽  
Particle Size Distributions ◽  
Secondary Aerosol

Abstract. In-situ measurements of vertically resolved particle size distributions based on a tethered balloon system were carried out for the first time in the highland city of Lhasa over the Tibetan Plateau in summer 2020, using portable optical counters for the size range of 0.124~32 μm. The vertical structure of 112 aerosol profiles was found to be largely shaped by the evolution of the boundary layer (BL), with a nearly uniform distribution of aerosols within the daytime mixing layer and a sharp decline with the height in the shallow nocturnal boundary layer. During the campaign, the average mass concentration of particulate matters smaller than 2.5 μm in aerodynamic diameter (PM2.5) within the BL was around 3 μg m−3, almost four times of the amount in the free troposphere (FT), which was rarely affected by surface anthropogenic emissions. Though there was a lower level of particle mass in the residual layer (RL) than in the BL, a similarity in particle mass size distributions (PMSDs) suggested that particles in the RL might be of the same origin as particles in the BL. This was also in consistence with the source apportionment analysis based on the PMSDs. Three distinct modes were observed in the PMSDs for the BL and the RL. One mode was exclusively coarse particles up to roughly 15 μm and peaked around 5 μm. More than 50 % of total particle mass was often contributed by coarse mode particles in this area, which was thought to be associated with local dust resuspension. The mode peaking over 0.5~0.7 μm was representative of biomass burning on religious holidays and was found to be most pronounced on holiday mornings. The contribution from the religious burning factor rose from about 25 % on non-holidays to nearly 50 % on holiday mornings. The mode dominated by particles smaller than 0.3 μm was thought to be associated with combustion related emissions and/or secondary aerosol formation. In the FT coarse mode particles only accounted for less than 10 % of the total mass and particles larger than 5 μm were negligible. The predominant submicron particles in the FT might be related to secondary aerosol formation and the aging of existed particles. To give a full picture of aerosol physical and chemical properties and better understand the origin and impacts of aerosols in this area, intensive field campaigns involving measurements of vertically resolved aerosol chemical compositions in different seasons would be much encouraged in the future.

scholarly journals Particle formation at a continental background site: comparison of modelresults with observations

2002 ◽  
Vol 2 (6) ◽  
pp. 2413-2448
Author(s):  
U. Uhrner ◽  
W. Birmili ◽  
F. Stratmann ◽  
M. Wilck ◽  
I. J. Ackermann ◽  
...  
Keyword(s):  
Particle Size ◽  
Sulphuric Acid ◽  
Particle Number ◽  
Particle Formation ◽  
Rural Site ◽  
Size Distributions ◽  
Correction Factors ◽  
Convective Conditions ◽  
Particle Size Distributions ◽  
Measured Particle

Abstract. At Hohenpeissenberg (47°48'N, 11°07'E, 988 m asl), a rural site 200-300 m higher than the surrounding terrain, sulphuric acid concentrations, particle size distributions, and other trace gas concentrations were measured over a two and a half year period. Measured particle number concentrations and inferred particle surface area-concentrations were compared with box-model simulations based on a multimodal lognormal aerosol module that included a binary sulphuric acid water nucleation scheme. The calculated nucleation rates were corrected with a factor to match measured particle number concentrations. These corrections varied over a range of 10-3 - 1017. The correction factors were close to 1 for the measurements made in the winter, which represented stable thermal stratification and low wind conditions. In contrast, the correction factors were the largest for measurements made under strong convective conditions. Our comparison of measured and simulated particle size distributions suggest a distant particle-formation process under convective conditions near the interface of the mixed layer and the entrainment zone, followed by downward transport and particle growth. For stable stratification and low winds, our comparisons suggest that particles formed close to the measurement site.

The influence of volcano activity on aerosol formation over the Andes

2020 ◽  
Author(s):  
Federico Bianchi ◽  
Diego Aliaga ◽  
Qiaozhi Zha ◽  
Liine Heikkinen ◽  
Marcos Andrade ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Sulphuric Acid ◽  
Negative Ions ◽  
Particle Formation ◽  
Amazon Forest ◽  
Particle Nucleation ◽  
New Particle Formation ◽  
Aerosol Formation ◽  
Air Masses ◽  
Particle Sizer

&lt;p&gt;A significant fraction (&gt;50%) of cloud condensation nuclei (CCN) in the atmosphere arises from new particle formation (Dunne et al., 2016). While particle nucleation has been observed almost everywhere in the atmosphere, the mechanisms governing this process are still poorly understood and subject of on-going research. For example, it is still largely unknown which components participate in new-particle formation. Laboratory experiments and quantum chemical calculations have identified potential candidates that may play a role, including sulphuric acid, ions, ammonia, amines and highly oxygenated organic molecules (Kirkby et al., 2011; Almeida et al., 2013; Bianchi et al., 2016; Bianchi et al., 2019).&lt;/p&gt;&lt;p&gt;Here we present observations of the formation and growth of newly formed particles measured during intense volcano activities.&lt;/p&gt;&lt;p&gt;The measurements were conducted at Chacaltaya mountain station (5240 m a.s.l.) in Bolivia. The station is located on top of the Cordillera Real. It has air masses coming from the Amazon forest, La Paz and the Bolivian altiplano.&lt;/p&gt;&lt;p&gt;With the Chemical Ionization Atmospheric Pressure interface Time-Of-Light mass spectrometers (CI-APi-TOF) we measured H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;, the APi-TOF retrieved the chemical composition of positive and negative ions. Ion and particle size distributions were measured with the NAIS (Neutral cluster and Air Ion Spectrometer) and the SMPS (Scanning Mobility Particle Sizer), respectively. The PSM (Particle Sizer Magnifier) measured particles with a cut off that varied from 1-4 nm. Finally, with the ACSM (Aerosol Chemical Speciation Monitor) and the FIGAERO (Filter Inlet for Gases and AEROsols) we retrieved the aerosol chemical composition. Besides this set of instruments, other parameters were measured at the Chacaltaya GAW station.&lt;/p&gt;&lt;p&gt;During the intensive measurement campaign, air masses coming directly from volcano eruptions were detected by all our instruments. We were therefore able to determine the gas and particle chemical composition of the air mass. In addition to that, we observed several NPF events triggered by air masses coming from volcanic emissions. With this set of instruments, we were able to retrieve the chemical composition of the vapours leading to the formation of new particles. It was found that all the nucleation event observed during the volcano activity were triggered by sulphuric acid and ammonia. In the presentation we will show more details on the chemical and physical mechanism behind this process.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Almeida, J., et al., (2013) Nature 502, 359-363.&lt;/p&gt;&lt;p&gt;Bianchi, F., et al., (2016) Science 6289, 1109-1112.&lt;/p&gt;&lt;p&gt;Bianchi, F., et al., (2019) Chemical Review 119, 3472&amp;#8722;3509&lt;/p&gt;&lt;p&gt;Dunne et al., (2016) Science 354, 1119-1124.&lt;/p&gt;&lt;p&gt;Kirkby, J., et al., (2011) Nature 476, (7361), 429-433.&lt;/p&gt;

scholarly journals Particle size distributions from laboratory-scale biomass fires using fast response instruments

2010 ◽  
Vol 10 (4) ◽  
pp. 8595-8621 ◽  
Author(s):  
S. Hosseini ◽  
L. Qi ◽  
D. Cocker ◽  
D. Weise ◽  
A. Miller ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Geometric Mean ◽  
Biomass Combustion ◽  
Climate Modelling ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Mean Diameter ◽  
Particle Sizer

Abstract. Particle size distribution from biomass combustion is an important parameter as it affects air quality, climate modelling and health effects. To date particle size distributions reported from prior studies vary not only due to difference in fuels but also difference in experimental conditions. This study aims to report characteristics of particle size distribution in a well controlled repeatable lab scale biomass fires for southwestern US fuels. The combustion facility at the USDA Forest Service's Fire Science Laboratory (FSL), Missoula, MT provided repeatable combustion and dilution environment ideal for particle size distribution study. For a variety of fuels tested the major mode of particle size distribution was in the range of 29 to 52 nm, which was attributable to dilution of the fresh smoke. Comparing volume size distribution from Fast Mobility Particle Sizer (FMPS) and Aerodynamic Particle Sizer (APS) measurements, ~30% of particle volume was attributable to the particles ranging from 0.5 to 10 μm for PM10. Geometric mean diameter rapidly increased during flaming and gradually decreased during mixed and smoldering phase combustion. Most of fuels gave unimodal distribution during flaming phase and strong biomodal distribution during smoldering phase. The mode of combustion (flaming, mixed and smoldering) could be better distinguished using slopes in Modified Combustion Efficiency (MCE) vs. geometric mean diameter from each mode of combustion than only using MCE values.

scholarly journals Physical and chemical properties of the regional mixed layer of Mexico's Megapolis Part II: evaluation of measured and modeled trace gases and particle size distributions

2012 ◽  
Vol 12 (21) ◽  
pp. 10161-10179 ◽  
Author(s):  
C. Ochoa ◽  
D. Baumgardner ◽  
M. Grutter ◽  
J. Allan ◽  
J. Fast ◽  
...  
Keyword(s):  
Particle Size ◽  
Standard Deviation ◽  
Transport Model ◽  
Trace Gases ◽  
Research Station ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Air Masses ◽  
Accumulation Mode ◽  
Mountain Site

Abstract. This study extends the work of Baumgardner et al. (2009) in which measurements of trace gases and particles, at a remote, high altitude mountain site, 60 km from Mexico City were analyzed with respect to the origin of the air masses. In the current evaluation, the temperature, water vapor mixing ratio (WMR), ozone (O3), carbon monoxide (CO), sulfur dioxide (SO2) and acyl peroxy nitrate (APN) are simulated with the WRF-Chem chemical transport model and compared with the measurements at the mountain site. Comparisons between the model and measurements are also evaluated for particle size distributions (PSDs) of the mass concentrations of sulfate, nitrate, ammonium and organic mass (OM). The model predictions of the diurnal trends in temperature, WMR and trace gases were generally well correlated; 13 of the 18 correlations were significant at a confidence level of <0.01. Less satisfactory were the average hourly differences between model and measurements that showed predicted values within expected, natural variation for only 10 of the 18 comparisons. The model performed best when comparing with the measurements during periods when the air originated from the east. In that case all six of the parameters being compared had average differences between the model and measurements less than the expected standard deviation. For the cases when the air masses are from the southwest or west northwest, only two of the comparisons from each case showed differences less than the expected standard deviation. The differences appear to be a result of an overly rapid growth of the boundary layer predicted by the model and too much dilution. There also is more O3 being produced, most likely by photochemical production, downwind of the emission sources than is predicted by the model. The measured and modeled PSD compare very well with respect to their general shape and the diameter of the peak concentrations. The spectra are log normally distributed with most of the mass in the accumulation mode centered at 200 ± 20 nm and little observed or predicted changes with respect to the time when the RML is above the Altzomoni research station. Only the total mass changes with time and air mass origin. The invariability of average diameter of the accumulation mode suggests that there is very little growth of the particles by condensation or coagulation after six hours of aging downwind of the major sources of anthropogenic emissions in Mexico's Megapolis. This could greatly simplify parameterization in climate models although it is not known at this time if this invariance can be extended to other megacity regions.

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