scholarly journals Influences of Primary Emission and Secondary Coating Formation on the Particle Diversity and Mixing State of Black Carbon Particles

2019 ◽  
Vol 53 (16) ◽  
pp. 9429-9438 ◽  
Author(s):  
Alex K.Y. Lee ◽  
Laura-Hélèna Rivellini ◽  
Chia-Li Chen ◽  
Jun Liu ◽  
Derek J. Price ◽  
...  
Keyword(s):  
Black Carbon ◽  
Mixing State ◽  
Carbon Particles ◽  
Coating Formation

scholarly journals Measurements of the Diversity of Shape and Mixing State for Ambient Black Carbon Particles

2021 ◽  
Vol 48 (17) ◽  
Author(s):  
Kang Hu ◽  
Dantong Liu ◽  
Ping Tian ◽  
Yangzhou Wu ◽  
Zhaoze Deng ◽  
...  
Keyword(s):  
Black Carbon ◽  
Mixing State ◽  
Carbon Particles

Mixing State of Black Carbon Particles in Asian Outflow Observed at a Remote Site in Taiwan in the Spring of 2017

2020 ◽  
Vol 125 (16) ◽  
Author(s):  
Cuizhi Sun ◽  
Kouji Adachi ◽  
Kentaro Misawa ◽  
Hing Cho Cheung ◽  
Charles C.‐K. Chou ◽  
...  
Keyword(s):  
Black Carbon ◽  
Mixing State ◽  
Remote Site ◽  
Carbon Particles

scholarly journals Morphology and mixing of black carbon particles collected in central California during the CARES field study

2016 ◽  
Vol 16 (22) ◽  
pp. 14515-14525 ◽  
Author(s):  
Ryan C. Moffet ◽  
Rachel E. O'Brien ◽  
Peter A. Alpert ◽  
Stephen T. Kelly ◽  
Don Q. Pham ◽  
...  
Keyword(s):  
Black Carbon ◽  
Central Valley ◽  
Photochemical Activity ◽  
Urban Site ◽  
Mixing State ◽  
Data Set ◽  
Carbon Particles ◽  
Aerosol Absorption ◽  
Scanning Transmission ◽  
Rural Sites

Abstract. Aerosol absorption is strongly dependent on the internal heterogeneity (mixing state) and morphology of individual particles containing black carbon (BC) and other non-absorbing species. Here, we examine an extensive microscopic data set collected in the California Central Valley during the CARES 2010 field campaign. During a period of high photochemical activity and pollution buildup, the particle mixing state and morphology were characterized using scanning transmission X-ray microscopy (STXM) at the carbon K-edge. Observations of compacted BC core morphologies and thick organic coatings at both urban and rural sites provide evidence of the aged nature of particles, highlighting the importance of highly aged particles at urban sites during periods of high photochemical activity. Based on the observation of thick coatings and more convex BC inclusion morphology, either the aging was rapid or the contribution of fresh BC emissions at the urban site was relatively small compared to background concentrations. Most particles were observed to have the BC inclusion close to the center of the host. However, host particles containing inorganic rich inclusions had the BC inclusion closer to the edge of the particle. These measurements of BC morphology and mixing state provide important constraints for the morphological effects on BC optical properties expected in aged urban plumes.

scholarly journals Measurement of the mixing state, mass, and optical size of individual black carbon particles in urban and biomass burning emissions

2008 ◽  
Vol 35 (13) ◽  
Author(s):  
J. P. Schwarz ◽  
R. S. Gao ◽  
J. R. Spackman ◽  
L. A. Watts ◽  
D. S. Thomson ◽  
...  
Keyword(s):  
Black Carbon ◽  
Biomass Burning ◽  
Mixing State ◽  
Carbon Particles

scholarly journals Droplet activation behaviour of atmospheric black carbon particles in fog as a function of their size and mixing state

2019 ◽  
Vol 19 (4) ◽  
pp. 2183-2207 ◽  
Author(s):  
Ghislain Motos ◽  
Julia Schmale ◽  
Joel C. Corbin ◽  
Marco Zanatta ◽  
Urs Baltensperger ◽  
...  
Keyword(s):  
Black Carbon ◽  
Single Particle ◽  
Radiative Forcing ◽  
Mixing State ◽  
Scanning Mobility Particle Sizer ◽  
Carbon Particles ◽  
Kohler Theory ◽  
Droplet Activation ◽  
Aerosol Cloud Interactions ◽  
A Minor

Abstract. Among the variety of particle types present in the atmosphere, black carbon (BC), emitted by combustion processes, is uniquely associated with harmful effects to the human body and substantial radiative forcing of the Earth. Pure BC is known to be non-hygroscopic, but its ability to acquire a coating of hygroscopic organic and inorganic material leads to increased diameter and hygroscopicity, facilitating droplet activation. This affects BC radiative forcing through aerosol–cloud interactions (ACIs) and BC life cycle. To gain insights into these processes, we performed a field campaign in winter 2015–2016 in a residential area of Zurich which aimed at establishing relations between the size and mixing state of BC particles and their activation to form droplets in fog. This was achieved by operating a CCN counter (CCNC), a scanning mobility particle sizer (SMPS), a single-particle soot photometer (SP2) and an aerosol chemical speciation monitor (ACSM) behind a combination of a total- and an interstitial-aerosol inlet. Our results indicate that in the morning hours of weekdays, the enhanced traffic emissions caused peaks in the number fraction of externally mixed BC particles, which do not act as CCN within the CCNC. The very low effective peak supersaturations (SSpeak) occurring in fog (between approximately 0.03 % and 0.06 % during this campaign) restrict droplet activation to a minor fraction of the aerosol burden (around 0.5 % to 1 % of total particle number concentration between 20 and 593 nm) leading to very selective criteria on diameter and chemical composition. We show that bare BC cores are unable to activate to fog droplets at such low SSpeak, while BC particles surrounded by thick coating have very similar activation behaviour to BC-free particles. Using simplified κ-Köhler theory combined with the ZSR mixing rule assuming spherical core–shell particle geometry constrained with single-particle measurements of respective volumes, we found good agreement between the predicted and the directly observed size- and mixing-state-resolved droplet activation behaviour of BC-containing particles in fog. This successful closure demonstrates the predictability of their droplet activation in fog with a simplified theoretical model only requiring size and mixing state information, which can also be applied in a consistent manner in model simulations.

scholarly journals Droplet activation behaviour of atmospheric black carbon particles in fog as a function of their size and mixing state

2018 ◽  
Author(s):  
Ghislain Motos ◽  
Julia Schmale ◽  
Joel Christopher Corbin ◽  
Marco Zanatta ◽  
Urs Baltensperger ◽  
...  
Keyword(s):  
Black Carbon ◽  
Single Particle ◽  
Radiative Forcing ◽  
Cloud Condensation Nuclei ◽  
Mixing State ◽  
Scanning Mobility Particle Sizer ◽  
Carbon Particles ◽  
Hygroscopic Properties ◽  
Droplet Activation ◽  
Aerosol Cloud Interactions

Abstract. Among the variety of particle types present in the atmosphere, black carbon (BC), emitted by combustion processes, is uniquely associated with harmful effects to the human body and substantial radiative forcing of the Earth. Pure BC is known to be non-hygroscopic, but its ability to acquire a coating of hygroscopic organic and inorganic material leads to increased hygroscopicity as well as diameter, facilitating droplet activation. This affects BC radiative forcing through aerosol-cloud interactions (aci) and BC life cycle. To gain insights into these processes, we performed a field campaign in winter 2015/16 in a residential area of Zurich which aimed at distinguishing different particle mixing states regarding hygroscopic properties in the cloud condensation nuclei (CCN)-activated fraction spectrum of urban aerosol and establishing relations between the mixing state of BC and its activation to form droplets in fog. This was achieved by operating a CCN counter (CCNC), a scanning mobility particle sizer (SMPS), a single particle soot photometer (SP2) and an aerosol chemical speciation monitor (ACSM) behind a combination of a total- and an interstitial-aerosol inlet. Our results indicate that, depending on the time of the day, we sampled both heavily aged internally mixed BC from background air advected to the site and freshly emitted externally mixed BC from local or regional traffic sources. During rush hours in the morning of weekdays, we found clear evidence that the enhanced traffic emissions caused peaks in the number fraction of externally mixed BC particles which do not act as CCN within the CCNC. The mixing state of BC particles was also found to play a key role in their ability to form fog droplets. The very low effective peak supersaturations (SSpeak) occurring in fog (between approximately 0.03 and 0.06 % during this campaign) restrict droplet activation to a minor fraction of the aerosol burden (around 0.5 to 1 % of total particle number concentration between 20 and 593 nm) leading to very selective criteria on diameter and chemical composition. We show that bare BC cores are unable to activate to fog droplets at such low SSpeak, while BC particles surrounded by thick coating have a very similar activation behavior as BC-free particles. The threshold coating thickness required for activation was shown to decrease with increasing BC core size. Using simplified κ-Köhler theory combined with the ZSR mixing rule assuming spherical core-shell particle geometry constrained with single particle measurements of respective volumes, we found good agreement between the predicted and the directly observed size and mixing state resolved droplet activation behaviour of BC-containing particles in fog. This successful closure demonstrates the predictability of their droplet activation in fog with a simplified theoretical model only requiring size and mixing state information, which can also be applied in a consistent manner in model simulations.

scholarly journals Characterising Mass-resolved Mixing State of Black Carbon in Beijing Using a Morphology-Independent Measurement Method

2019 ◽  
Author(s):  
Chenjie Yu ◽  
Dantong Liu ◽  
Kurtis Broda ◽  
Rutambhara Joshi ◽  
Jason Olfert ◽  
...  
Keyword(s):  
Black Carbon ◽  
Formation Mechanism ◽  
Coating Thickness ◽  
Process Models ◽  
Urban Site ◽  
Pollution Level ◽  
Inversion Method ◽  
Mixing State ◽  
Coating Formation ◽  
Coating Formation Mechanism

Abstract. Refractory Black Carbon (rBC) in the atmosphere is known for its significant impact on the climate system in the atmosphere. The relationship between the microphysical and optical properties of rBC remain uncertain and are largely influenced by the size, coating thickness and mixing state of particles. This study presents a coupling of a centrifugal particle mass analyser (CPMA) and a single particle soot photometer (SP2) for the morphology-independent quantification of the mixing state of rBC-containing particles, used in the urban site of Beijing as part of the Air Pollution and Human Health-Beijing (APHH-Beijing) project during winter (10th Nov–10th Dec) and summer (18th May–25th June). An inversion method is applied to the measurements to present a two-variable distribution of both rBC core mass and total mass of rBC-containing particles and present the mass-resolved mixing state of rBC-containing particles. The mass ratio between non-rBC coating and rBC core (MR) is calculated to determine the coating thickness of the rBC-containing particles. The bulk MR was found to vary between 2–12 in winter and between 2–3 in summer. This mass-resolved mixing state is used to derive the mixing state index (χ) for the rBC-containing particles. χ quantifies whether the coating is evenly distributed across the rBC-containing particle population and is used to determine the degree of internal and external mixture of rBC-containing particles. The rBC-containing particles in Beijing were found to be 55%–70 % internally mixed in winter depending on the dominant air masses. χ of rBC-containing particles was highly positively associated with increased bulk MR, rBC mass loading or pollution level in winter, whereas χ of rBC-containing particles in summer varied significantly (ranging 60 %–75 %) within the narrowly-distributed bulk MR and was found to be independent of air mass sources. This concludes that the bulk MR may only act as a predictor of mixing state in winter, and χ is better to quantify the mixing state of rBC-containing particles. The same level of bulk MR corresponded with a higher χ in summer than in winter and this tended to suggest a limited formation of coatings on rBC largely depended on primary sources. However, with the higher Non-refractory PM1 (NR-PM1) concentration in winter, the coagulation process may still lead relative thick coatings. In summer the higher secondary compounds made the rBC-containing particles more homogeneous. But due to the higher temperatures and limited pollution level, the coating thickness in summer is limited. The mixing state of rBC-containing particles should also depend on the coating formation mechanism, both primary source influence and secondary coating formation mechanism should be considered in interpreting the rBC-containing particles mixing state in the atmosphere. This particle morphology-independent and mass-based data format as introduced in this study could be conviently applied in particle-resolved or other process models to investigate atmospheric rBC aging and mixing state properties.

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