scholarly journals Effect of Pollution Level on Size Distributions and Mixing State of Ambient Black Carbon Particles in an Urban Area during Wintertime

2021 ◽  
Vol 21 ◽  
pp. 200655
Author(s):  
Kangning Li ◽  
XiaoFei Wang ◽  
Xiaohui Lu ◽  
Hong Chen ◽  
Xin Yang
Keyword(s):  
Black Carbon ◽  
Urban Area ◽  
Pollution Level ◽  
Size Distributions ◽  
Mixing State ◽  
Carbon Particles

scholarly journals Size distributions of elemental carbon in the atmosphere of a coastal urban area in South China: characteristics, evolution processes, and implications for the mixing state

2008 ◽  
Vol 8 (19) ◽  
pp. 5843-5853 ◽  
Author(s):  
X.-F. Huang ◽  
J. Z. Yu
Keyword(s):  
Urban Area ◽  
Elemental Carbon ◽  
Southern China ◽  
Global Climate ◽  
Particle Growth ◽  
Size Distributions ◽  
Hygroscopic Growth ◽  
Mixing State ◽  
Cloud Processing ◽  
Fine Mode

Abstract. Elemental carbon (EC), as one of the primary light-absorbing components in the atmosphere, has a significant impact on both regional and global climate. The environmental impacts of EC are strongly dependent on its particle size. Little is known about the size distribution characteristics of EC particles in China's ambient environments. We report size distributions of EC particles in the urban area of Shenzhen in Southern China. In our samples, EC was consistently found in two modes, a fine mode and a coarse mode. The majority of EC mass (~80%) in this coastal metropolitan city resided in particles smaller than 3.2 μm in diameter. The fine mode peaked at around either 0.42 μm or 0.75 μm. While the mode at 0.42 μm could be ascribed to fresh vehicular emissions in the region, the mode at 0.75 μm was likely a result of particle growth from smaller EC particles. We theoretically investigated the particle growth processes that caused the EC particles to grow from 0.42 μm to 0.75 µm in the atmosphere. Our calculations indicate that the EC peak at 0.75 μm was not produced through either coagulation or H2SO4 condensation; both processes are too slow to lead to significant EC growth. Hygroscopic growth was also determined to be insignificant. Instead, addition of sulfate through in-cloud processing was found to cause significant growth of the EC particles and to explain the EC peak at 0.75 μm. We also estimated the mixing state of EC from the EC size distributions. In the droplet size, at least 45–60% of the EC mass in the summer samples and 68% of the EC mass in the winter samples was internally mixed with sulfate as a result of in-cloud processing. This information on EC should be considered in models of the optical properties of aerosols in this region. Our results also suggest that the in-cloud processing of primary EC particles could increase the light absorbing capacities through mixing EC with sulfate.

scholarly journals Size distribution and coating thickness of black carbon from the Canadian oil sands operations

2017 ◽  
Author(s):  
Yuan Cheng ◽  
Shao-Meng Li ◽  
Mark Gordon ◽  
Peter Liu
Keyword(s):  
Size Distribution ◽  
Black Carbon ◽  
Coating Thickness ◽  
Oil Sands ◽  
Radiative Forcing ◽  
Climate Models ◽  
Source Area ◽  
Size Distributions ◽  
Mixing State ◽  
Earth’S Climate

Abstract. Black carbon (BC) plays an important role in the Earth’s climate system. However, parameterization of BC size and mixing state have not been well addressed in aerosol-climate models, introducing substantial uncertainties into the estimation of radiative forcing by BC. In this study, we focused on BC emissions from the massive oil sands (OS) industry in northern Alberta, based on an aircraft campaign conducted over the Athabasca OS region in 2013. A total of 14 flights were made over the OS source area, in which the aircraft was typically flown in a 4- or 5-sided polygon pattern along flight tracks encircling an OS facility. Another 3 flights were performed downwind of the OS source area, each of which involved at least three intercepting locations where the well-mixed OS plume was measured along flight tracks perpendicular to the wind direction. Comparable size distributions were observed for refractory black carbon (rBC) over and downwind of the OS facilities, with rBC mass median diameters (MMD) between ~ 135 and 145 nm that were characteristic of fresh urban emissions. This MMD range corresponded to rBC number median diameters (NMD) of ~ 60–70 nm, approximately 100 % higher than the NMD settings in some aerosol-climate models. The typical in- and out-of-plume segments of a flight, which had different rBC concentrations and photochemical ages, showed consistent rBC size distributions. Moreover, rBC size distributions remained unchanged at different downwind distances from the source area, suggesting that atmospheric aging would not necessarily change rBC size distribution. However, aging indeed influenced rBC mixing state. Coating thickness for rBC cores in the diameter range of 130–160 nm was nearly doubled within three hours when the OS plume was transported over a distance of 90 km from the source area.

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 Modeled source apportionment of black carbon particles coated with a light-scattering shell

2020 ◽  
Author(s):  
Aki Virkkula
Keyword(s):  
Black Carbon ◽  
Biomass Burning ◽  
Fossil Fuel ◽  
Size Distributions ◽  
Core Size ◽  
Carbon Particles ◽  
Aerosol Mass ◽  
Measured Absorption ◽  
Absorbing Material ◽  
Fossil Fuel Emissions

Abstract. The Aethalometer model been used widely for estimating the contributions of fossil fuel emissions and biomass burning to equivalent black carbon (eBC). The calculation is based on measured absorption Ångström exponents (αabs). The interpretation αabs is ambiguous since it is well-known that it not only depends on the dominant absorber but also on the size and internal structure of the particles, core size and shell thickness. In this work the uncertainties of the Aethalometer-model-derived apparent fractions of absorption by eBC from fossil fuel and biomass burning are evaluated with a core-shell Mie model. Biomass-burning fractions (BB(%)) were calculated for pure and coated single BC particles, for lognormal unimodal and bimodal size distributions of BC cores coated with ammonium sulfate, a scattering-only material. BB(%) was very seldom 0 % even though BC was the only absorbing material in the simulations. The shape of size distribution plays an important role. Narrow size distributions result in higher αabs and BB(%) values than wide size distributions. The sensitivity of αabs and BB(%) to variations in shell volume fractions is the highest for accumulation mode particles. This is important because that is where the largest aerosol mass is. For the interpretation of absorption Ångström exponents it would be very good to measure BC size distributions and shell thicknesses together with the wavelength dependency of absorption.

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 Aerosol in a Heavily Polluted Urban Area of China: Implications for Light Absorption Enhancement

2014 ◽  
Vol 48 (7) ◽  
pp. 689-697 ◽  
Author(s):  
Qiyuan Wang ◽  
R.-J. Huang ◽  
Junji Cao ◽  
Yongming Han ◽  
Gehui Wang ◽  
...  
Keyword(s):  
Black Carbon ◽  
Urban Area ◽  
Light Absorption ◽  
Absorption Enhancement ◽  
Mixing State ◽  
Black Carbon Aerosol
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