scholarly journals Black carbon physical properties and mixing state in the European megacity Paris

2012 ◽  
Vol 12 (9) ◽  
pp. 25121-25180 ◽  
Author(s):  
M. Laborde ◽  
M. Crippa ◽  
T. Tritscher ◽  
Z. Jurányi ◽  
P. F. DeCarlo ◽  
...  
Keyword(s):  
Size Distribution ◽  
Black Carbon ◽  
Biomass Burning ◽  
Traffic Emissions ◽  
Core Mass ◽  
Air Mass ◽  
Air Masses ◽  
Mass Size Distribution ◽  
Mass Size ◽  
A Minor

Abstract. Aerosol hygroscopicity and black carbon (BC) properties were characterised during wintertime in Paris, one of the biggest European megacities. Hygroscopic growth factor (GF) distributions, characterised by distinct modes of more-hygroscopic background aerosol and non- or slightly hygroscopic aerosol of local (or regional) origin, revealed an increase of the relative contribution of the local sources compared to the background aerosol with decreasing particle size. BC particles in Paris were mainly originating from fresh traffic emissions, whereas biomass burning was only a minor contribution. The mass size distribution of the BC cores peaked on average at a BC core mass equivalent diameter of DMEV≈150 nm. The BC particles were moderately coated (Δcoat≈30 nm on average for BC cores with DMEV =160–260 nm) and an average mass absorption coefficient (MAC) of ~8.6 m2 g−1 at the wavelength λ = 880 nm was observed. Different time periods were selected to investigate the properties of BC particles as a function of source and air mass type. The traffic emissions were found to be non-hygroscopic (GF ≈ 1.0), and essentially all particles with a dry mobility diameter larger than D0 = 110 nm contained a BC core. BC from traffic emissions was further characterised by literally no coating (Δcoat ≈2 nm), the smallest maximum of the BC core mass size distribution (DMEV≈100 nm) and the smallest MAC (~7.3 m2 g−1 at λ = 880 nm). The biomass burning aerosol was slightly more-hygroscopic than the traffic emissions (with a distinct slightly hygroscopic mode peaking at GF≈1.1–1.2). Furthermore, only a minor fraction (⩽10%) of the slightly hygroscopic particles with GF⩾1.1 (and D0 = 265 nm) contained a detectable BC core. The BC particles from biomass burning were found to have a medium coating thickness as well as slightly larger mean BC core sizes and MAC values compared to traffic emissions. The aerosol observed under the influence of aged air masses and air masses from Eastern Continental Europe was dominated by a more-hygroscopic mode peaking at GF≈1.6. Most particles (95%) with a D0 = 265 nm, in this mode, did not contain a detectable BC core. A significant fraction of the BC particles had a substantial coating with non-refractory aerosol components. MAC values of ~8.8 m2g−1 and ~8.3 m2 g−1 at λ = 880 nm and mass mean BC core diameters of 150 nm and 200 nm were observed for the aged and continental air mass types, respectively. The reason for the larger BC core sizes compared to the fresh emissions – transport effects or a different BC source – remains unclear. The dominant fraction of the BC-containing particles was found to have no or very little coating with non-refractory matter. The lack of coatings is consistent with the observation that the BC particles are non- or slightly hygroscopic, which makes them poor cloud condensation nuclei.

scholarly journals Black carbon physical properties and mixing state in the European megacity Paris

2013 ◽  
Vol 13 (11) ◽  
pp. 5831-5856 ◽  
Author(s):  
M. Laborde ◽  
M. Crippa ◽  
T. Tritscher ◽  
Z. Jurányi ◽  
P. F. Decarlo ◽  
...  
Keyword(s):  
Size Distribution ◽  
Biomass Burning ◽  
Coating Thickness ◽  
Traffic Emissions ◽  
Core Mass ◽  
Air Mass ◽  
Air Masses ◽  
Mass Size ◽  
A Minor ◽  
Wet Removal

Abstract. Aerosol hygroscopicity and refractory black carbon (rBC) properties were characterised during wintertime at a suburban site in Paris, one of the biggest European cities. Hygroscopic growth factor (GF) frequency distributions, characterised by distinct modes of more-hygroscopic background aerosol and non- or slightly hygroscopic aerosol of local (or regional) origin, revealed an increase of the relative contribution of the local sources compared to the background aerosol with decreasing particle size. BC-containing particles in Paris were mainly originating from fresh traffic emissions, whereas biomass burning only gave a minor contribution. The mass size distribution of the rBC cores peaked on average at an rBC core mass equivalent diameter of DMEV ~ 150 nm. The BC-containing particles were moderately coated (coating thickness Δcoat ~ 33 nm on average for rBC cores with DMEV = 180–280 nm) and an average mass absorption coefficient (MAC) of ~ 8.6 m2 g−1 at the wavelength λ = 880 nm was observed. Different time periods were selected to investigate the properties of BC-containing particles as a function of source and air mass type. The traffic emissions were found to be non-hygroscopic (GF ≈ 1.0), and essentially all particles with a dry mobility diameter (D0) larger than D0 = 110 nm contained an rBC core. rBC from traffic emissions was further observed to be uncoated within experimental uncertainty (Δcoat ~ 2 nm ± 10 nm), to have the smallest BC core sizes (maximum of the rBC core mass size distribution at DMEV ~ 100 nm) and to have the smallest MAC (~ 7.3 m2g−1 at λ = 880 nm). The biomass burning aerosol was slightly more hygroscopic than the traffic emissions (with a distinct slightly-hygroscopic mode peaking at GF ≈ 1.1–1.2). Furthermore, only a minor fraction (≤ 10%) of the slightly-hygroscopic particles with 1.1 ≤ GF ≤ 1.2 (and D0 = 265 nm) contained a detectable rBC core. The BC-containing particles from biomass burning were found to have a medium coating thickness as well as slightly larger mean rBC core sizes and MAC values compared to traffic emissions. The aerosol observed under the influence of aged air masses and air masses from Eastern Continental Europe was dominated by a~more-hygroscopic mode peaking at GF ≈ 1.6. Most particles (95%), in the more-hygroscopic mode at D0 = 265 nm, did not contain a detectable rBC core. A significant fraction of the BC-containing particles had a substantial coating with non-refractory aerosol components. MAC values of ~ 8.8 m2g−1 and ~ 8.3 m2g−1 at λ = 880 nm and mass mean rBC core diameters of 150 nm and 200 nm were observed for the aged and continental air mass types, respectively. The reason for the larger rBC core sizes compared to the fresh emissions – transport effects or a different rBC source – remains unclear. The dominant fraction of the BC-containing particles was found to have no or very little coating with non-refractory matter. The lack of coatings is consistent with the observation that the BC-containing particles are non- or slightly-hygroscopic, which makes them poor cloud condensation nuclei. It can therefore be expected that wet removal through nucleation scavenging is inefficient for fresh BC-containing particles in urban plumes. The mixing-state-specific cloud droplet activation behaviour of BC-containing particles including the effects of atmospheric aging processes should be considered in global simulations of atmospheric BC, as the wet removal efficiency remains a major source of uncertainty in its life-cycle.

scholarly journals Size distribution and source of black carbon aerosol in urban Beijing during winter haze episodes

2016 ◽  
Author(s):  
Yunfei Wu ◽  
Xiaojia Wang ◽  
Jun Tao ◽  
Rujin Huang ◽  
Ping Tian ◽  
...  
Keyword(s):  
Size Distribution ◽  
Black Carbon ◽  
Urban Areas ◽  
Late Winter ◽  
Equivalent Diameter ◽  
Air Masses ◽  
A Value ◽  
Significant Linear Correlation ◽  
Mass Size ◽  
Black Carbon Aerosol

Abstract. Black carbon (BC) plays an important role in the climate and environment due to its light absorption, which is greatly dependent on its physicochemical properties including morphology, size and mixing state. The size distribution of the refractory BC (rBC) in urban Beijing during the late winter in 2014 was revealed by measurements obtained using a single particle soot photometer (SP2), when the hazes occurred frequently. By assuming void-free rBC with a density of 1.8 g cm−3, the mass of the rBC showed an approximately lognormal distribution as a function of the volume-equivalent diameter (VED), for which there was a peak diameter of 213 nm. This size distribution agreed well with those observed in other urban areas of China. Larger VED values of the rBC were observed during polluted periods than on clean days, implying an alteration in the rBC sources, as the mass-size of the rBC from a certain source varied little once it was emitted into the atmosphere. The potential source contribution functions showed that air masses from the south to east of the observation site brought a higher rBC loading with more thick coatings and larger core sizes. The mean VED of the rBC (VEDrBC) presented a significant linear correlation with the number fraction of thickly coated rBC (NFcoated); the VED of the entirely externally mixed rBC was inferred as the y-intercept of the linear regression. This VED, with a value of ~150 nm, was considered as the typical mean VED of the rBC from local traffic sources in this study. Accordingly, the contribution of the local traffic to the rBC was estimated based on reasonable assumptions. Local traffic contributed 35 to 100 % of the hourly rBC mass concentration with a mean of 59 %, during this campaign. A lower local traffic contribution was observed during polluted periods, suggesting increasing contributions of other sources (e.g., coal combustion/biomass burning) to the rBC. The heavy pollution in Beijing was greatly influenced by other sources in addition to the local traffic.

Mass size distribution of major monosaccharide anhydrides and mass contribution of biomass burning

2019 ◽  
Vol 220 ◽  
pp. 1-9 ◽  
Author(s):  
Zoltán Imre Blumberger ◽  
Anikó Vasanits-Zsigrai ◽  
Gergő Farkas ◽  
Imre Salma
Keyword(s):  
Size Distribution ◽  
Biomass Burning ◽  
Mass Size Distribution ◽  
Mass Size ◽  
Monosaccharide Anhydrides

scholarly journals Role of black carbon mass size distribution in the direct aerosol radiative forcing

2019 ◽  
Vol 19 (20) ◽  
pp. 13175-13188 ◽  
Author(s):  
Gang Zhao ◽  
Jiangchuan Tao ◽  
Ye Kuang ◽  
Chuanyang Shen ◽  
Yingli Yu ◽  
...  
Keyword(s):  
Size Distribution ◽  
Black Carbon ◽  
Radiative Forcing ◽  
Climate Models ◽  
Radiative Effects ◽  
Aerosol Radiative Forcing ◽  
Mass Size Distribution ◽  
Mass Size ◽  
Mixing States ◽  
Aerosol Radiative

Abstract. Large uncertainties exist when estimating radiative effects of ambient black carbon (BC) aerosol. Previous studies about the BC aerosol radiative forcing mainly focus on the BC aerosols' mass concentrations and mixing states, while the effects of BC mass size distribution (BCMSD) were not well considered. In this paper, we developed a method of measuring the BCMSD by using a differential mobility analyzer in tandem with an Aethalometer. A comprehensive method of multiple charging corrections was proposed and implemented in measuring the BCMSD. Good agreement was obtained between the BC mass concentration integrated from this system and that measured in the bulk phase, demonstrating the reliability of our proposed method. Characteristics of the BCMSD and corresponding radiative effects were studied based on a field measurement campaign conducted in the North China Plain by using our own measurement system. Results showed that the BCMSD had two modes and the mean peak diameters of the modes were 150 and 503 nm. The BCMSD of the coarser mode varied significantly under different pollution conditions with peak diameter varying between 430 and 580 nm, which gave rise to significant variation in aerosol bulk optical properties. The direct aerosol radiative forcing was estimated to vary by 8.45 % for different measured BCMSDs of the coarser mode, which shared the same magnitude with the variation associated with assuming different aerosol mixing states (10.5 %). Our study reveals that the BCMSD as well as its mixing state in estimating the direct aerosol radiative forcing matters. Knowledge of the BCMSD should be fully considered in climate models.

scholarly journals Single particle characterization of black carbon aerosol in the Northeast Tibetan Plateau, China

2012 ◽  
Vol 12 (8) ◽  
pp. 21947-21976 ◽  
Author(s):  
Q. Y. Wang ◽  
J. P. Schwarz ◽  
J. J. Cao ◽  
R. S. Gao ◽  
D. W. Fahey ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Size Distribution ◽  
Black Carbon ◽  
Single Particle ◽  
Qinghai Lake ◽  
Equivalent Diameter ◽  
The Tibetan Plateau ◽  
Mass Size Distribution ◽  
Low Concentrations ◽  
Mass Size

Abstract. Refractory black carbon (rBC) mass, size distribution, and mixing state were measured with a ground-based Single Particle Soot Photometer (SP2) at Qinghai Lake (QHL), a rural area in the Northeastern Tibetan Plateau of China, during October 2011. The average measured rBC mass concentration of 0.36 μg STP-m−3 is significantly higher than the concentrations measured in background and remote regions around the globe. The diurnal variation of rBC concentration showed nocturnal peak and afternoon low concentrations and showed a loose anticorrelation to the variation of mixed layer depths, indicating nighttime trapping of emissions and daytime ventilation. The high rBC values and their diurnal behavior strongly suggest that the QHL area was heavily influenced by local rBC sources. The mass size distribution of rBC showed a primary mode peak at 175-nm diameter and a small secondary mode peak at 495 nm volume-equivalent diameter assuming 2 g cm−3 void free density. About 40% of the observed rBC particles within the detectable size range were mixed with large amounts of non-refractory materials present as a thick coating. A comparison of the Aethalometer and SP2 measurements suggests that there are non-BC species strongly affecting the Aethalometer measurement and, therefore, the Aethalometer measurements are not reliable for rBC determinations in the Tibetan Plateau region without artifact corrections. The apparent black-carbon specific, mass-absorption cross section derived from the Aethalometer and SP2 data was 37.5 m2 g−1 at a wavelength of 880 nm. A strong correlation was found between rBC and CO with a slope of 1.5 ± 0.1 ng STP-m−3 ppbv−1, similar to values of mixed rural emissions.

scholarly journals Single particle characterization of black carbon aerosols at a tropospheric alpine site in Switzerland

2010 ◽  
Vol 10 (15) ◽  
pp. 7389-7407 ◽  
Author(s):  
D. Liu ◽  
M. Flynn ◽  
M. Gysel ◽  
A. Targino ◽  
I. Crawford ◽  
...  
Keyword(s):  
Particle Size ◽  
Absorption Coefficient ◽  
Size Distribution ◽  
Black Carbon ◽  
Single Particle ◽  
Free Troposphere ◽  
Mass Loading ◽  
Mixing State ◽  
Mass Size Distribution ◽  
Mass Size

Abstract. The refractory black carbon (rBC) mass, size distribution (190–720 nm) and mixing state in sub-micron aerosols were characterized from late February to March 2007 using a single particle incandescence method at the high alpine research station Jungfraujoch (JFJ), Switzerland (46.33° N, 7.59° E, 3580 m a.s.l.). JFJ is a ground based location, which is at times exposed to continental free tropospheric air. A median mass absorption coefficient (MAC) of 10.2±3.2 m2 g−1 at λ=630 nm was derived by comparing single particle incandescence measurements of black carbon mass with continuous measurements of absorption coefficient. This value is comparable with other estimates at this location. The aerosols measured at the site were mostly well mixed and aged during transportation via the free troposphere. Pollutant sources were traced by air mass back trajectories, trace gases concentrations and the mass loading of rBC. In southeasterly wind directions, mixed or convective weather types provided the potential to vent polluted boundary layer air from the southern Alpine area and industrial northern Italy, delivering enhanced rBC mass loading and CN concentrations to the JFJ. The aerosol loadings at this site were also significantly influenced by precipitation, which led to the removal of rBC from the atmosphere. Precipitation events were shown to remove about 65% of the rBC mass from the free tropospheric background reducing the mean loading from 13±5 ng m−3 to 6±2 ng m−3(corrected to standard temperature and pressure). Overall, 40±15% of the observed rBC particles within the detectable size range were mixed with large amounts of non-refractory materials present as a thick coating. The growth of particle size into the accumulation mode was positively linked with the degree of rBC mixing, suggesting the important role of condensable materials in increasing particle size and leading to enhanced internal mixing of these materials with rBC. It is the first time that BC mass, size distribution and mixing state are reported in the free troposphere over Europe. These ground based measurements also provide the first temporal study of rBC in the European free troposphere quantitatively measured by single particle methods. At the present time there is only limited information of BC and its mixing state in the free troposphere, especially above Europe. The results reported in this paper provide an important constraint on modelled representation of BC.

scholarly journals Size distribution and mixing state of black carbon particles during a heavy air pollution episode in Shanghai

2016 ◽  
Vol 16 (8) ◽  
pp. 5399-5411 ◽  
Author(s):  
Xianda Gong ◽  
Ci Zhang ◽  
Hong Chen ◽  
Sergey A. Nizkorodov ◽  
Jianmin Chen ◽  
...  
Keyword(s):  
Air Pollution ◽  
Size Distribution ◽  
Black Carbon ◽  
Biomass Burning ◽  
Single Particle ◽  
Traffic Emissions ◽  
Traffic Emission ◽  
Pollution Episode ◽  
Condensation Mode ◽  
Biomass Burning Particles

Abstract. A Single Particle Aerosol Mass Spectrometer (SPAMS), a Single Particle Soot Photometer (SP2) and various meteorological instruments were employed to investigate the chemical and physical properties of black carbon (BC) aerosols during a regional air pollution episode in urban Shanghai over a 5-day period in December 2013. The refractory black carbon (rBC) mass concentrations measured by SP2 averaged 3.2 µg m−3, with the peak value of 12.1 µg m−3 at 04:26 LT on 7 December. The number of BC-containing particles captured by SPAMS in the size range 200–1200 nm agreed very well with that detected by SP2 (R2 = 0.87). A cluster analysis of the single particle mass spectra allowed for the separation of BC-containing particles into five major classes: (1) Pure BC; (2) BC attributed to biomass burning (BBBC); (3) K-rich BC-containing (KBC); (4) BC internally mixed with OC and ammonium sulfate (BCOC-SOx); (5) BC internally mixed with OC and ammonium nitrate (BCOC-NOx). The size distribution of internally mixed BC particles was bimodal. Detected by SP2, the condensation mode peaked around  ∼  230 nm and droplet mode peaked around  ∼  380 nm, with a clear valley in the size distribution around  ∼  320 nm. The condensation mode mainly consisted of traffic emissions, with particles featuring a small rBC core (∼  60–80 nm) and a relatively thin absolute coating thickness (ACT,  ∼  50–130 nm). The droplet mode included highly aged traffic emission particles and biomass burning particles. The biomass burning particles had a larger rBC core (∼  80–130 nm) and a thick ACT (∼  110–300 nm). The highly aged traffic emissions had a smaller core (∼  60–80 nm) and a very thick ACT (∼  130–300 nm), which is larger than reported in any previous literature. A fast growth rate (∼  20 nm h−1) of rBC with small core sizes was observed during the experiment. High concentrations pollutants like NO2 likely accelerated the aging process and resulted in a continuous size growth of rBC-containing particles from traffic emission.

scholarly journals Single particle characterization of black carbon aerosols at a tropospheric alpine site in Switzerland

2010 ◽  
Vol 10 (4) ◽  
pp. 8765-8810 ◽  
Author(s):  
D. Liu ◽  
M. Flynn ◽  
M. Gysel ◽  
A. Créso Targino ◽  
I. Crawford ◽  
...  
Keyword(s):  
Particle Size ◽  
Absorption Coefficient ◽  
Size Distribution ◽  
Black Carbon ◽  
Single Particle ◽  
Free Troposphere ◽  
Mass Loading ◽  
Mixing State ◽  
Mass Size Distribution ◽  
Mass Size

Abstract. Black carbon (BC) mass, size distribution and mixing state in sub-micron aerosols were characterized from late February to March 2007 using a single particle incandescence method at the high alpine research station Jungfraujoch (JFJ), Switzerland (46.33° N, 7.59° E, 3580 m a.s.l.). JFJ is a ground based location, which is at times exposed to continental free tropospheric air. A median mass absorption coefficient (MAC) of 10.2±3.2 m2 g−1 at λ = 630 nm was derived by comparing single particle incandescence measurements of black carbon mass with continuous measurements of absorption coefficient. This value is comparable with other estimates at this location. The aerosols measured at the site were mostly well mixed and aged during transportation via the free troposphere. Pollutant sources were traced by air mass back trajectories, trace gases concentrations and the mass loading of BC. In southeasterly wind directions, mixed or convective weather types provided the potential to vent polluted boundary layer air from the southern Alpine area and industrial northern Italy, delivering enhanced BC mass loading and CN concentrations to the JFJ. The aerosol loadings at this site were also significantly influenced by precipitation, which led to the removal of BC from the atmosphere. Precipitation events were shown to remove about 65% of the BC mass from the free tropospheric background reducing the mean loading from 10±5 ngm−3 to 4±2 ngm−3. Overall, 40±15% of the observed BC particles within the detectable size range were mixed with large amounts of non-refractory materials present as a thick coating around the BC core. The growth of particle size into the accumulation mode was positively linked with the degree of BC mixing, suggesting the important role of condensable materials in increasing particle size as well as enhancing BC mixing state. It is the first time that BC mass, size distribution and mixing state are reported in the free troposphere over Europe. These ground based measurements also provide the first temporal study of BC in the European free troposphere quantitatively measured by single particle methods. At the present time there is only limited information of BC and its mixing state in the free troposphere, especially above Europe. The results reported in this paper provide an important constraint on modelled representation of BC.

scholarly journals Chemically speciated mass size distribution, particle effective density and origin of non-refractory PM<sub>1 </sub>measured at a rural background site in Central Europe

2021 ◽  
Author(s):  
Petra Pokorná ◽  
Naděžda Zíková ◽  
Radek Lhotka ◽  
Petr Vodička ◽  
Saliou Mbengue ◽  
...  
Keyword(s):  
Size Distribution ◽  
Long Range ◽  
Central Europe ◽  
Effective Density ◽  
Long Range Transport ◽  
Air Masses ◽  
Mass Size Distribution ◽  
Background Site ◽  
Range Transport ◽  
Mass Size

Abstract. The seasonal variability of non-refractory PM1 (NR-PM1) was studied at a rural background site (National Atmospheric Observatory Košetice – NAOK) in the Czech Republic to examine the impact of atmospheric regional and long-range transport in Central Europe. NR-PM1 measurements were performed by compact time-of-flight aerosol mass spectrometry (C-ToF-AMS), and the chemically speciated mass size distributions, effective density, and origin were discussed. The average PM1 concentrations, calculated as the sum of the NR-PM1 (after collection efficiency corrections – CE corrections of 0.4 and 0.33 in summer and winter, respectively) and the equivalent black carbon (eBC) concentrations measured by an aethalometer (AE), were 8.58 ± 3.70 μg m−3 in summer and 10.08 ± 8.04 μg m−3 in winter. Organics dominated during both campaigns (summer/winter: 4.97 ± 2.92/4.55 ± 4.40 μg m−3), followed by sulphate in summer (1.68 ± 0.81/1.36± 1.38 μg m−3) and nitrate in winter (0.67 ± 0.38/2.03 ± 1.71 μg m−3). The accumulation mode dominated the average mass size distribution during both seasons, with larger particles of all species measured in winter (mode diameters: Org: 334/413 nm, NO3−: 377/501 nm, SO42−: 400/547 nm, and NH4+: 489/515 nm) pointing to regional and long-range transport. However, since the winter aerosols were less oxidized than the summer aerosols (comparing fragments f44 and f43), the importance of local sources in the cold part of the year was not negligible. The average PM1 particle effective density, defined as the ratio of the mass to the volume of a particle, corresponded to higher inorganic contents during both seasons (summer: ∼ 1.30 g cm−3 and winter: ∼ 1.40 g cm−3). However, the effective densities during episodes of higher mass concentrations calculated based on the particle number (mobility diameter) and mass size distribution (vacuum aerodynamic diameter) were even higher, ranging from 1.40–1.60 g cm−3 in summer and from 1.40–1.75 g cm−3 in winter. Although aged continental air masses from the SE were rare in summer (7 %), they were connected with the highest concentrations of all NR-PM1 species, especially sulphate and ammonium. In winter, slow continental air masses from the SW (44 %) were linked to inversion conditions over Central Europe and were associated with the highest concentrations among all NR-PM1 measurements.

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