Source apportionment of aerosol particles at a European air pollution hot spot using particle number size distributions and chemical composition

2018 ◽  
Vol 234 ◽  
pp. 145-154 ◽  
Author(s):  
Cecilia Leoni ◽  
Petra Pokorná ◽  
Jan Hovorka ◽  
Mauro Masiol ◽  
Jan Topinka ◽  
...  
Keyword(s):  
Air Pollution ◽  
Chemical Composition ◽  
Source Apportionment ◽  
Particle Number ◽  
Hot Spot ◽  
Aerosol Particles ◽  
Size Distributions

scholarly journals Source apportionment of ambient fine particle from combined size distribution and chemical composition data during summertime in Beijing

2013 ◽  
Vol 13 (1) ◽  
pp. 1367-1397 ◽  
Author(s):  
Z. R. Liu ◽  
Y. S. Wang ◽  
Q. Liu ◽  
B. Hu ◽  
Y. Sun
Keyword(s):  
Chemical Composition ◽  
Power Plant ◽  
Source Apportionment ◽  
Particle Number ◽  
Road Dust ◽  
Number Concentration ◽  
Particle Number Concentration ◽  
Size Distributions ◽  
Composition Data ◽  
Regional Sources

Abstract. Continuous particle number concentration and chemical composition data were collected over one month during summertime in Beijing to investigate the source apportionment of ambient fine particles. Particle size distributions from 15 nm to 2.5 μm in diameter and composition data, such as organic matter, sulfate, nitrate, ammonium, chlorine, and gaseous pollutants, were analyzed using positive matrix factorisation (PMF) which indentified eight factors: cooking, solid mode exhaust, nucleation mode exhaust, accumulation mode, secondary nitrate, secondary sulfate, coal-fired power plant and road dust. Nearly two-thirds of particle number concentrations were attributed to cooking (22.8%) and motor vehicle (37.5%), whereas road dust, coal-fired power plant and regional sources contributed 69.0% to particle volume concentrations. Local and remote sources were distinguished using size distributions associated with each factor. Local sources were generally characterised by unimodal or bimodal number distributions, consisting mostly of particles less 0.1 μm in diameter, and regional sources were defined by mostly accumulation mode particles. Nearly one third of secondary nitrate and secondary sulfate was transported from the surrounding areas of Beijing during study period. Overall the introduction of combination of particle number concentration and chemical composition in PMF model is successful at separating the components and quantifying relative contributions to the particle number and volume population in a complex urban atmosphere.

Size-segregated aerosol in a hot-spot pollution urban area: Chemical composition and three-way source apportionment

2017 ◽  
Vol 231 ◽  
pp. 601-611 ◽  
Author(s):  
V. Bernardoni ◽  
M. Elser ◽  
G. Valli ◽  
S. Valentini ◽  
A. Bigi ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Source Apportionment ◽  
Urban Area ◽  
Hot Spot

scholarly journals Cloud activation properties of aerosol particles in a continental Central European urban environment

2021 ◽  
Vol 21 (14) ◽  
pp. 11289-11302
Author(s):  
Imre Salma ◽  
Wanda Thén ◽  
Máté Vörösmarty ◽  
András Zénó Gyöngyösi
Keyword(s):  
Chemical Composition ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Number Concentration ◽  
Urban Aerosol ◽  
Condensation Nuclei ◽  
Frequency Distributions ◽  
Remote Locations ◽  
Cloud Activation

Abstract. Collocated measurements using a condensation particle counter, differential mobility particle sizer and cloud condensation nuclei counter were realised in parallel in central Budapest from 15 April 2019 to 14 April 2020 to gain insight into the cloud activation properties of urban aerosol particles. The median total particle number concentration was 10.1 × 103 cm−3. The median concentrations of cloud condensation nuclei (CCN) at water vapour supersaturation (S) values of 0.1 %, 0.2 %, 0.3 %, 0.5 % and 1.0 % were 0.59, 1.09, 1.39, 1.80 and 2.5 × 103 cm−3, respectively. The CCN concentrations represented 7–27 % of all particles. The CCN concentrations were considerably larger but the activation fractions were systematically substantially smaller than observed in regional or remote locations. The effective critical dry particle diameters (dc,eff) were derived utilising the CCN concentrations and particle number size distributions. Their median values at the five supersaturation values considered were 207, 149, 126, 105 and 80 nm, respectively; all of these diameters were positioned within the accumulation mode of the typical particle number size distribution. Their frequency distributions revealed a single peak for which the geometric standard deviation increased monotonically with S. This broadening indicated high time variability in the activating properties of smaller particles. The frequency distributions also showed fine structure, with several compositional elements that seemed to reveal a consistent or monotonical tendency with S. The relationships between the critical S and dc,eff suggest that urban aerosol particles in Budapest with diameters larger than approximately 130 nm showed similar hydroscopicity to corresponding continental aerosol particles, whereas smaller particles in Budapest were less hygroscopic than corresponding continental aerosol particles. Only modest seasonal cycling in CCN concentrations and activation fractions was seen, and only for large S values. This cycling likely reflects changes in the number concentration, chemical composition and mixing state of the particles. The seasonal dependencies of dc,eff were featureless, indicating that the droplet activation properties of the urban particles remained more or less the same throughout the year. This is again different from what is seen in non-urban locations. Hygroscopicity parameters (κ values) were computed without determining the time-dependent chemical composition of the particles. The median values for κ were 0.15, 0.10, 0.07, 0.04 and 0.02, respectively, at the five supersaturation values considered. The averages suggested that the larger particles were considerably more hygroscopic than the smaller particles. We found that the κ values for the urban aerosol were substantially smaller than those previously reported for aerosols in regional or remote locations. All of these characteristics can be linked to the specific source composition of particles in cities. The relatively large variability in the hygroscopicity parameters for a given S emphasises that the individual values represent the CCN population in ambient air while the average hygroscopicity parameter mainly corresponds to particles with sizes close to the effective critical dry particle diameter.

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 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 Spatio-temporal variability and principal components of the particle number size distribution in an urban atmosphere

2008 ◽  
Vol 8 (5) ◽  
pp. 18155-18217 ◽  
Author(s):  
F. Costabile ◽  
W. Birmili ◽  
S. Klose ◽  
T. Tuch ◽  
B. Wehner ◽  
...  
Keyword(s):  
Particle Number ◽  
Aerosol Particles ◽  
Urban Traffic ◽  
Urban Atmosphere ◽  
Urban Aerosol ◽  
Size Distributions ◽  
Spatial Coverage ◽  
Temporal Persistence ◽  
Spatio Temporal ◽  
20 Nm

Abstract. Due to the presence of diffusive anthropogenic sources in urban areas, the spatio-temporal variability of fine (diameter <1 μm) and ultrafine (<0.1 μm) aerosol particles has been a challenging issue in particle exposure assessment as well as atmospheric research in general. We examined number size distributions of atmospheric aerosol particles (size range 3–800 nm) that were measured simultaneously at a maximum of eight observation sites in and around a city in Central Europe (Leipzig, Germany). Two main experiments were conducted with different time span and number of observation sites (2 years at 3 sites; 1 month at 8 sites). A general observation was that the particle number size distribution varied in time and space in a complex fashion as a result of interaction between local and far-range sources, and the meteorological conditions. To identify statistically independent factors in the urban aerosol, different runs of principal component analysis were conducted encompassing aerosol, gas phase, and meteorological parameters from the multiple sites. Several of the resulting principal components, outstanding with respect to their temporal persistence and spatial coverage, could be associated with aerosol particle modes: a first accumulation mode ("droplet mode", 300–800 nm), considered to be the result of liquid phase processes and far-range transport; a second accumulation mode (centered around diameters 90–250 nm), considered to result from primary emissions as well as aging through condensation and coagulation; an Aitken mode (30–200 nm) linked to urban traffic emissions in addition to an urban and a rural Aitken mode; a nucleation mode (5–20 nm) linked to urban traffic emissions; nucleation modes (3–20 nm) linked to photochemically induced particle formation; an aged nucleation mode (10–50 nm). A number of additional components were identified to represent only local sources at a single site each, or infrequent phenomena. In summary, the analysis of size distributions of high time and size resolution yielded a surprising wealth of statistical aerosol components occurring in the urban atmosphere over one single city. Meanwhile, satisfactory physical explanations could be found for the components with the greatest temporal persistence and spatial coverage. Therefore a paradigm on the behaviour of sub-μm urban aerosol particles is proposed, with recommendations how to efficiently monitor individual sub-fractions across an entire city.

scholarly journals Cloud droplet activation in a continental Central European urban environment

2021 ◽  
Author(s):  
Imre Salma ◽  
Wanda Thén ◽  
Máté Vörösmarty ◽  
András Zénó Gyöngyösi
Keyword(s):  
Chemical Composition ◽  
Particle Number ◽  
Aerosol Particles ◽  
Ambient Air ◽  
Geometric Standard Deviation ◽  
Time Variability ◽  
Urban Aerosol ◽  
Large Variability ◽  
Frequency Distributions ◽  
Droplet Activation

Abstract. Collocated measurements by condensation particle counter, differential mobility particle sizer and cloud condensational nuclei counter instruments were realised in parallel in central Budapest from 15 April 2019 to 14 April 2020 to gain insight into the droplet activation behaviour of urban aerosol particles. The median total particle number concentration was 10.1 × 103 cm−3. The median concentrations of cloud condensation nuclei (CCN) at water vapour supersaturations (Ss) of 0.1, 0.2, 0.3, 0.5 and 1.0 % were 0.59, 1.09, 1.39, 1.80 and 2.5 × 103 cm−3, respectively. They represented from 7 to 27 % of the total particles. The effective critical dry particle diameters (dc,eff) were derived utilising the CCN concentrations and particle number size distributions. Their medians were 207, 149, 126, 105 and 80 nm, respectively. They were all positioned within the accumulation mode of the typical particle number size distribution. Their frequency distributions revealed a single peak, which geometric standard deviation increased monotonically with S. The broadening indicated larger time variability in the activation properties of smaller particles. The frequency distributions also showed a fine structure. Its several compositional elements seemed to change in a tendentious manner with S. They were related to the size-dependent chemical composition and external mixtures of particles. The relationships between the critical S and dc,eff suggested that the urban aerosol particles in Budapest with a diameter larger than approximately 130 nm showed similar hygroscopicity than the continental aerosol in general, while the smaller particles appeared to be less hygroscopic than that. Seasonal cycling of the CCN concentrations and activation fractions implied modest alterations and for the larger Ss only. They likely reflected the changes in particle number concentrations, chemical composition and mixing state of particles. The seasonal dependencies for dc,eff were featureless, which indicated that the urban particles exhibited more or less similar droplet activation properties over the measurement year. This is different from non-urban locations. The hygroscopicity parameters (κ values) were computed without determining time-dependent chemical composition of particles. Their medians were 0.16, 0.10, 0.07, 0.04 and 0.02, respectively. The averages suggested that the larger particles exhibited considerably higher hygroscopicity than the smaller particles. The urban aerosol was characterised by substantially smaller kappa values than for regional or remote locations. All these could be virtually linked to specific source composition in cities. The relatively large variability in the hygroscopicity parameter sets for a given S emphasized that their individual values represented the CCN population in the ambient air, while the averages stood mainly for the particles with a size close to the effective critical dry particle diameters.

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