scholarly journals Winter and summer time size distributions and densities of traffic-related aerosol particles at a busy highway in Helsinki

2006 ◽  
Vol 6 (9) ◽  
pp. 2411-2421 ◽  
Author(s):  
A. Virtanen ◽  
T. Rönkkö ◽  
J. Kannosto ◽  
J. Ristimäki ◽  
J. M. Mäkelä ◽  
...  
Keyword(s):  
Particle Density ◽  
Aerosol Particles ◽  
Geometric Mean ◽  
Average Density ◽  
Average Particle ◽  
Size Distributions ◽  
Nucleation Mode ◽  
Mode 2 ◽  
Traffic Rate ◽  
Summer Time

Abstract. Number concentrations and size distributions of traffic related aerosol particles were measured at a roadside in Helsinki during two winter campaigns (10–26 February 2003, 28 January–12 February 2004) and two summer campaigns (12–27 August 2003, 6–20 August 2004). The measurements were performed simultaneously at distances of 9 m and 65 m from the highway. Total number concentrations were measured by a condensation particle counter (CPC) and particle size distributions by a scanning mobility particle sizer (SMPS) and an electrical low pressure impactor (ELPI). This study concentrates on data that were measured when the wind direction was from the road to the measurement site. The total concentrations in the wintertime were 2–3 times higher than in the summertime and the concentrations were dominated by nucleation mode particles. The particles smaller than 63 nm (aerodynamic diameter) constituted ~90% of all particles in the wintertime and ~80% of particles in the summer time. The particle total concentration increased with increasing traffic rate. The effect of traffic rate on particles smaller than 63 nm was stronger than on the larger particles. The particle distributions at the roadside consisted of two distinguishable modes. The geometric mean diameter (GMD) of nucleation mode (Mode 1) was 20.3 nm in summer and 18.9 nm in winter. The GMD of the larger mode consisting mostly of traffic related soot particles (Mode 2) was 72.0 nm in summer and 75.1 nm in winter. The GMD values of the modes did not depend on the traffic rate. The average particle density for each mode was determined by a parallel density fitting method based on the size distribution measurement made by ELPI and SMPS. The average density value for Mode 1 particles was 1.0±0.13 g/cm3 and 1.0±0.07 g/cm3 both in summer and winter respectively, while the average density value for Mode 2 was 1.5±0.1 g/cm3 and 1.8±0.3 g/cm3 for summer and winter, respectively.

scholarly journals Winter and summer time size distributions and densities of traffic-related aerosol particles at a busy highway in Helsinki

2006 ◽  
Vol 6 (1) ◽  
pp. 549-578 ◽  
Author(s):  
A. Virtanen ◽  
T. Rönkkö ◽  
J. Kannosto ◽  
J. M. Mäkelä ◽  
J. Keskinen ◽  
...  
Keyword(s):  
Particle Distribution ◽  
Total Concentration ◽  
Average Density ◽  
Size Distributions ◽  
Nucleation Mode ◽  
The Road ◽  
Mode 2 ◽  
Traffic Rate ◽  
Winter Time ◽  
Summer Time

Abstract. The number concentration and size distribution of traffic related particles were measured at road-side in Helsinki. Two winter campaigns took place in 10–26 February 2003 and 28 January–12 February 2004 and two summer campaigns in 12–27 August 2003 and 6–20 August 2004. The measurements were performed simultaneously at distances of 9 m and 65 m from the highway. This study concentrates on data that were measured when the wind direction was from the road to the measurement site. The total concentration in winter time was 2–3 times higher than in summer time and it was dominated by nucleation mode particles. The particles smaller than 63 nm (at aerodynamic size) constitute ~90% of all particles in winter time and ~80% of particles in summer time. The particle total concentration increases with increasing traffic rate. The dependence of particles smaller than 63 nm on traffic rate is stronger than for particles larger than 63 nm both during summer and winter. The particle distribution at the roadside consists of two distinguishable modes. The GMD of nucleation mode (Mode 1) was 20.3 nm at summer and 18.9 nm at winter. The GMD of the larger mode (Mode 2) was 72.0 nm at summer and 75.1 nm at winter. The GMD values of the modes do not depend on traffic rate. The average density value for Mode 1 particles was 1.0 g/cm3 both in summer and winter time, while the average density value for Mode 2 was 1.5±0.1 g/cm3 and 1.8±0.3 g/cm3 for summer and winter time, respectively.

Size distributions of sea-source aerosol particles: A physical explanation of observed nearshore versus open-sea differences

1987 ◽  
Vol 92 (D12) ◽  
pp. 14850 ◽  
Author(s):  
H. Sievering ◽  
J. Boatman ◽  
L. Gunter ◽  
H. Horvath ◽  
D. Wellman ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Size Distributions ◽  
Physical Explanation ◽  
Open Sea

scholarly journals Inhalers and nebulizers: basic principles and preliminary measurements

2018 ◽  
Vol 180 ◽  
pp. 02068
Author(s):  
Ondrej Misik ◽  
Frantisek Lizal ◽  
Vahid Farhikhteh Asl ◽  
Miloslav Belka ◽  
Jan Jedelsky ◽  
...  
Keyword(s):  
Hospital Care ◽  
Aerosol Particles ◽  
Experimental Setup ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Basic Principles ◽  
Physical Mechanisms ◽  
Inhaled Particles ◽  
Human Airways ◽  
Inhaled Medication

Inhalers are hand-held devices which are used for administration of therapeutic aerosols via inhalation. Nebulizers are larger devices serving for home and hospital care using inhaled medication. This contribution describes the basic principles of dispersion of aerosol particles used in various types of inhalers and nebulizers, and lists the basic physical mechanisms contributing to the deposition of inhaled particles in the human airways. The second part of this article presents experimental setup, methodology and preliminary results of particle size distributions produced by several selected inhalers and nebulizers.

scholarly journals Size-resolved particle number emissions in Beijing determined from measured particle size distributions

2020 ◽  
Vol 20 (19) ◽  
pp. 11329-11348 ◽  
Author(s):  
Jenni Kontkanen ◽  
Chenjuan Deng ◽  
Yueyun Fu ◽  
Lubna Dada ◽  
Ying Zhou ◽  
...  
Keyword(s):  
Particle Size ◽  
Air Quality ◽  
Particle Number ◽  
Aerosol Particles ◽  
Urban Environments ◽  
Integrated Assessment Model ◽  
Assessment Model ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Measured Particle

Abstract. The climate and air quality effects of aerosol particles depend on the number and size of the particles. In urban environments, a large fraction of aerosol particles originates from anthropogenic emissions. To evaluate the effects of different pollution sources on air quality, knowledge of size distributions of particle number emissions is needed. Here we introduce a novel method for determining size-resolved particle number emissions, based on measured particle size distributions. We apply our method to data measured in Beijing, China, to determine the number size distribution of emitted particles in a diameter range from 2 to 1000 nm. The observed particle number emissions are dominated by emissions of particles smaller than 30 nm. Our results suggest that traffic is the major source of particle number emissions with the highest emissions observed for particles around 10 nm during rush hours. At sizes below 6 nm, clustering of atmospheric vapors contributes to calculated emissions. The comparison between our calculated emissions and those estimated with an integrated assessment model GAINS (Greenhouse Gas and Air Pollution Interactions and Synergies) shows that our method yields clearly higher particle emissions at sizes below 60 nm, but at sizes above that the two methods agree well. Overall, our method is proven to be a useful tool for gaining new knowledge of the size distributions of particle number emissions in urban environments and for validating emission inventories and models. In the future, the method will be developed by modeling the transport of particles from different sources to obtain more accurate estimates of particle number emissions.

scholarly journals In situ observations of aerosol particles remaining from evaporated cirrus crystals: Comparing clean and polluted air masses

2002 ◽  
Vol 2 (5) ◽  
pp. 1599-1633 ◽  
Author(s):  
M. Seifert ◽  
J. Ström ◽  
R. Krejci ◽  
A. Minikin ◽  
A. Petzold ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Aerosol Particles ◽  
Pollution Level ◽  
Size Distributions ◽  
Number Density ◽  
Particle Volume ◽  
The North ◽  
In Situ Observations

Abstract. In situ observations of aerosol particles contained in cirrus crystals are presented and compared to interstitial aerosol size distributions (non-activated particles in between the cirrus crystals). The observations were conducted in cirrus clouds in the Southern and Northern Hemisphere mid-latitudes during the INCA project. The first campaign in March and April 2000 was performed from Punta Arenas, Chile (54° S) in pristine air. The second campaign in September and October 2000 was performed from Prestwick, Scotland (53° N) in the vicinity of the North Atlantic flight corridor. Size distribution measurements of crystal residuals (particles remaining after evaporation of the crystals) show that small aerosol particles (Dp < 0.1µm) dominate the number density of residuals. The crystal residual size distributions were significantly different in the two campaigns. On average the residual size distributions were shifted towards larger sizes in the Southern Hemisphere. For a given integral residual number density, the calculated particle volume was on average three times larger in the Southern Hemisphere. This may be of significance to the vertical redistribution of aerosol mass by clouds in the tropopause region. In both campaigns the mean residual size increased with increasing crystal number density. The observations of ambient aerosol particles were consistent with the expected higher pollution level in the Northern Hemisphere. The fraction of residual particles only contributes to approximately a percent or less of the total number of particles, which is the sum of the residual and interstitial particles.

Soil fertility and leaf nutrient status of litchi orchard sites

2021 ◽  
Vol 30 (2) ◽  
pp. 141-149
Author(s):  
Tasnim Zannat ◽  
Farhana Firoz Meem ◽  
Rubaiat Sharmin Promi ◽  
Umme Qulsum Poppy ◽  
MK Rahman
Keyword(s):  
Particle Density ◽  
Organic Matter Content ◽  
Chemical Properties ◽  
Nutrient Status ◽  
Matter Content ◽  
Average Particle ◽  
Total N ◽  
Available N ◽  
Dominant Soil ◽  
Physico Chemical

Twelve soil and twelve leaf samples were collected from twelve litchi (Litchi chinensis Sonn.) orchards from different locations of Dinajpur to evaluate some physico-chemical properties and nutrient status of soil, and concentration of nutrients in litchi leaf. The pH of the soil varied from very strong acidic to medium acidic (4.8 - 5.7), organic matter content varied from 0.84 - 1.88%, EC varied from 302.4 - 310.2 μS/cm. The dominant soil textural class was clay loam. The average particle density was 2.49g/cm3. Total N, P, K and S in soils were 0.053 - 0.180%, 0.02 - 0.07%, 0.046 - 0.370 meq/100 g, and 0.015 - 0.028%, respectively. Available N, P, K, S, Zn, Fe, Mn and B in soils 30.40 - 57.8 mg/kg, 10.53 - 14.33 mg/kg, 0.03 - 0.32 meq/100 g, 20.03-34.80 mg/kg, 0.68-1.50 μg/g, 31.8 - 41.5 μg/g, 6.75 - 7.39 μg/g and 0.25-0.51 μg/g, respectively. The concentration of total N, P, K, S, Zn and Mn in the leaf were 1.74 - 2.20%, 0.11 - 0.188%, 0.104- 0.198%, 0.129 - 0.430%, 12 - 14 μg/g and 30 - 74 μg/g, respectively. The overall results indicated that the fertility status of the soils under the litchi plantation in the Dinajpur area are medium fertile. So, farmers could be advised to grow litchi plants after applying amendments to the soils to improve the physico-chemical properties in the Dinajpur area of Bangladesh. Dhaka Univ. J. Biol. Sci. 30(2): 141-149, 2021 (July)

scholarly journals Iodine speciation and size distribution in ambient aerosols at a coastal new particle formation hotspot in China

2019 ◽  
Vol 19 (6) ◽  
pp. 4025-4039 ◽  
Author(s):  
Huan Yu ◽  
Lili Ren ◽  
Xiangpeng Huang ◽  
Mingjie Xie ◽  
Jun He ◽  
...  
Keyword(s):  
Particle Formation ◽  
Coastal Areas ◽  
Aerosol Sample ◽  
Size Distributions ◽  
New Particle Formation ◽  
Nucleation Mode ◽  
Iodine Species ◽  
Organic Iodine ◽  
Iodine Compounds ◽  
Iodine Speciation

Abstract. Intense new particle formation (NPF) events were observed in the coastal atmosphere during algae growth and farming season at Xiangshan gulf of the east China coast. High nucleation-mode iodine concentrations measured by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) confirmed that the NPF events were induced by iodine species. Our study provides important information on iodine speciation, size distributions, and its role in NPF in the context of heavy air pollution in China's coastal areas. For the first time, we identified 5 inorganic iodine species, 45 organic iodine compounds (35 molecular formulas), and a group of iodide–organic adducts in aerosols. The concentrations and size distributions of iodine species down to 10 nm were measured during the iodine-induced NPF, continental NPF, and non-NPF days at the coastal site and compared to those at an inland site. The iodine in the above four aerosol sample types were characterized by iodate, aromatic iodine compounds, iodoacetic acid or iodopropenoic acid, and iodide–organic adducts, respectively. Iodide and organic iodine compounds were found in the nucleation-mode particles; however, it is still not clear whether they contributed to nucleation or just new particle growth. Wild algae, as well as farmed algae, could be an important NPF source in China's coastal areas.

scholarly journals Mass Extinction Efficiency Approximation for Polydispersed Aerosol Using Harmonic Mean-Type Approximation

2020 ◽  
Vol 10 (23) ◽  
pp. 8637
Author(s):  
Junshik Um ◽  
Seonghyeon Jang ◽  
Young Jun Yoon ◽  
Seoung Soo Lee ◽  
Ji Yi Lee ◽  
...  
Keyword(s):  
Optical Properties ◽  
Chemical Composition ◽  
Extinction Coefficient ◽  
Mass Extinction ◽  
Aerosol Particles ◽  
Size Distributions ◽  
Extinction Efficiency ◽  
Type Approximation ◽  
Aerosol Mass ◽  
Mass Extinction Efficiency

Among many parameters characterizing atmospheric aerosols, aerosol mass extinction efficiency (MEE) is important for understanding the optical properties of aerosols. MEE is expressed as a function of the refractive indices (i.e., composition) and size distributions of aerosol particles. Aerosol MEE is often considered as a size-independent constant that depends only on the chemical composition of aerosol particles. The famous Malm’s reconstruction equation and subsequent revised methods express the extinction coefficient as a function of aerosol mass concentration and MEE. However, the used constant MEE does not take into account the effect of the size distribution of polydispersed chemical composition. Thus, a simplified expression of size-dependent MEE is required for accurate and conventional calculations of the aerosol extinction coefficient and also other optical properties. In this study, a simple parameterization of MEE of polydispersed aerosol particles was developed. The geometric volume–mean diameters of up to 10 µm with lognormal size distributions and varying geometric standard deviations were used to represent the sizes of various aerosol particles (i.e., ammonium sulfate and nitrate, elemental carbon, and sea salt). Integrating representations of separate small mode and large mode particles using a harmonic mean-type approximation generated the flexible and convenient parameterizations of MEE that can be readily used to process in situ observations and adopted in large-scale numerical models. The calculated MEE and the simple forcing efficiency using the method developed in this study showed high correlations with those calculated using the Mie theory without losing accuracy.

scholarly journals Retrospection of Anti–Blood Group Antibody Proficiency Testing Data Using the Geometric Mean and Standard Deviation

2019 ◽  
Vol 153 (4) ◽  
pp. 530-536 ◽  
Author(s):  
John Jeongseok Yang ◽  
Yousun Chung ◽  
Hyungsuk Kim ◽  
Dae-Hyun Ko ◽  
Sang-Hyun Hwang ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Blood Group ◽  
Proficiency Testing ◽  
Geometric Mean ◽  
Geometric Standard Deviation ◽  
Geometric Means ◽  
Consensus Criterion ◽  
Mode 2 ◽  
Testing Data ◽  
The Mean

Abstract Objectives We reanalyzed the data from proficiency testing (PT) to assess the effect of the geometric mean in the statistical analysis of immunohematologic data. Methods Using the five most recent anti–blood group antibody titer participant summary results, the geometric mean (GM) ±2 × geometric standard deviation (GSD) was used as the comparative consensus criterion to mode ±2 titers. Results Using the PT evaluation criterion of mode ±2 titers, the mean percentages of participants with acceptable results were 97.5% and 97.8% for anti-A and anti-D, respectively. When applying GM ±2 GSD, the mean percentages of acceptable results were 96.1% (anti-A) and 96.1% (anti-D). The percentages of responses included in each consensus criterion were lower using GM ±2 GSD, with a few exceptions. Conclusions Geometric means are more robust and precise in visualizing the central tendency. This method can improve the statistical robustness of PT evaluations.

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