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 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 Emission characteristics of refractory black carbon aerosols from fresh biomass burning: a perspective from laboratory experiments

2017 ◽  
Vol 17 (21) ◽  
pp. 13001-13016 ◽  
Author(s):  
Xiaole Pan ◽  
Yugo Kanaya ◽  
Fumikazu Taketani ◽  
Takuma Miyakawa ◽  
Satoshi Inomata ◽  
...  
Keyword(s):  
Black Carbon ◽  
Biomass Burning ◽  
Combustion Efficiency ◽  
High Temporal Resolution ◽  
Equivalent Diameter ◽  
Emission Characteristics ◽  
Mixing State ◽  
Climate Effect ◽  
Essential Information ◽  
Background Values

Abstract. The emission characteristics of refractory black carbon (rBC) from biomass burning are essential information for numerical simulations of regional pollution and climate effects. We conducted combustion experiments in the laboratory to investigate the emission ratio and mixing state of rBC from the burning of wheat straw and rapeseed plants, which are the main crops cultivated in the Yangtze River Delta region of China. A single particle soot photometer (SP2) was used to measure rBC-containing particles at high temporal resolution and with high accuracy. The combustion state of each burning case was indicated by the modified combustion efficiency (MCE), which is calculated using the integrated enhancement of carbon dioxide and carbon monoxide concentrations relative to their background values. The mass size distribution of the rBC particles showed a lognormal shape with a mode mass equivalent diameter (MED) of 189 nm (ranging from 152 to 215 nm), assuming an rBC density of 1.8 g cm−3. rBC particles less than 80 nm in size (the lower detection limit of the SP2) accounted for ∼ 5 % of the total rBC mass, on average. The emission ratios, which are expressed as ΔrBC ∕ ΔCO (Δ indicates the difference between the observed and background values), displayed a significant positive correlation with the MCE values and varied between 1.8 and 34 ng m−3 ppbv−1. Multi-peak fitting analysis of the delay time (Δt, or the time of occurrence of the scattering peak minus that of the incandescence peak) distribution showed that rBC-containing particles with rBC MED  =  200 ± 10 nm displayed two peaks at Δt  =  1.7 µs and Δt  =  3.2 µs, which could be attributed to the contributions from both flaming and smoldering combustion in each burning case. Both the Δt values and the shell / core ratios of the rBC-containing particles clearly increased as the MCE decreased from 0.98 (smoldering-dominant combustion) to 0.86 (flaming-dominant combustion), implying the great importance of the rapid condensation of semi-volatile organics. This laboratory study found that the mixing state of rBC particles from biomass burning strongly depends on its combustion processes, and overall MCE should be taken carefully into consideration while the climate effect of rBC particles from open biomass burning is simulated.

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

scholarly journals Single particle characterization of biomass burning organic aerosol (BBOA): evidence for non-uniform mixing of high molecular weight organics and potassium

2015 ◽  
Vol 15 (22) ◽  
pp. 32157-32183 ◽  
Author(s):  
A. K. Y. Lee ◽  
M. D. Willis ◽  
R. M. Healy ◽  
J. M. Wang ◽  
C.-H. Jeong ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Black Carbon ◽  
High Molecular Weight ◽  
Biomass Burning ◽  
Single Particle ◽  
Critical Role ◽  
Organic Aerosol ◽  
Mixing State ◽  
Particle Measurements ◽  
Near Ultraviolet

Abstract. Biomass burning is a major source of black carbon (BC) and primary organic aerosol globally. In particular, biomass burning organic aerosol (BBOA) is strongly associated with atmospheric brown carbon (BrC) that absorbs near ultraviolet and visible light, resulting in significant impacts on regional visibility degradation and radiative forcing. The mixing state of BBOA can play a critical role in the prediction of aerosol optical properties. In this work, single particle measurements from a soot-particle aerosol mass spectrometer coupled with a light scattering module (LS-SP-AMS) were performed to examine the mixing state of BBOA, refractory black carbon (rBC) and potassium (K+, a tracer for biomass burning aerosol) in an air mass influenced by aged biomass burning. Cluster analysis of single particle measurements identified five BBOA-related particle types. rBC accounted for 3–14 w.t. % of these particle types on average. Only one particle type exhibited a strong ion signal for K+, with mass spectra characterized by low molecular weight organic species. The remaining four particle types were classified based on the apparent molecular weight of the BBOA constituents. Two particle types were associated with low potassium content and significant amounts of high molecular weight (HMW) organic compounds. Our observations indicate non-uniform mixing of particles within a biomass burning plume in terms of molecular weight and illustrate that HMW BBOA can be a key contributor to low-volatility BrC observed in BBOA particles.

scholarly journals Unexpected Biomass Burning Aerosol Absorption Enhancement Explained by Black Carbon Mixing State

2020 ◽  
Vol 47 (19) ◽  
Author(s):  
Cyrielle Denjean ◽  
Joel Brito ◽  
Quentin Libois ◽  
Marc Mallet ◽  
Thierry Bourrianne ◽  
...  
Keyword(s):  
Black Carbon ◽  
Biomass Burning ◽  
Absorption Enhancement ◽  
Mixing State ◽  
Aerosol Absorption ◽  
Biomass Burning Aerosol

scholarly journals Overview of aerosol optical properties over southern West Africa from DACCIWA aircraft measurements

2020 ◽  
Vol 20 (8) ◽  
pp. 4735-4756 ◽  
Author(s):  
Cyrielle Denjean ◽  
Thierry Bourrianne ◽  
Frederic Burnet ◽  
Marc Mallet ◽  
Nicolas Maury ◽  
...  
Keyword(s):  
Optical Properties ◽  
West Africa ◽  
Black Carbon ◽  
Biomass Burning ◽  
Aerosol Particles ◽  
Anthropogenic Pollution ◽  
Aerosol Optical Properties ◽  
Air Masses ◽  
Carbon Particles ◽  
Biomass Burning Particles

Abstract. Southern West Africa (SWA) is an African pollution hotspot but a relatively poorly sampled region of the world. We present an overview of in situ aerosol optical measurements collected over SWA in June and July 2016 as part as of the DACCIWA (Dynamics-Aerosol-Chemistry-Clouds Interactions in West Africa) airborne campaign. The aircraft sampled a wide range of air masses, including anthropogenic pollution plumes emitted from the coastal cities, long-range transported biomass burning plumes from central and southern Africa and dust plumes from the Sahara and Sahel region, as well as mixtures of these plumes. The specific objective of this work is to characterize the regional variability of the vertical distribution of aerosol particles and their spectral optical properties (single scattering albedo: SSA, asymmetry parameter, extinction mass efficiency, scattering Ångström exponent and absorption Ångström exponent: AAE). The first findings indicate that aerosol optical properties in the planetary boundary layer were dominated by a widespread and persistent biomass burning loading from the Southern Hemisphere. Despite a strong increase in aerosol number concentration in air masses downwind of urban conglomerations, spectral SSA were comparable to the background and showed signatures of the absorption characteristics of biomass burning aerosols. In the free troposphere, moderately to strongly absorbing aerosol layers, dominated by either dust or biomass burning particles, occurred occasionally. In aerosol layers dominated by mineral dust particles, SSA varied from 0.81 to 0.92 at 550 nm depending on the variable proportion of anthropogenic pollution particles externally mixed with the dust. For the layers dominated by biomass burning particles, aerosol particles were significantly more light absorbing than those previously measured in other areas (e.g. Amazonia, North America), with SSA ranging from 0.71 to 0.77 at 550 nm. The variability of SSA was mainly controlled by variations in aerosol composition rather than in aerosol size distribution. Correspondingly, values of AAE ranged from 0.9 to 1.1, suggesting that lens-coated black carbon particles were the dominant absorber in the visible range for these biomass burning aerosols. Comparison with the literature shows a consistent picture of increasing absorption enhancement of biomass burning aerosol from emission to remote location and underscores that the evolution of SSA occurred a long time after emission. The results presented here build a fundamental basis of knowledge about the aerosol optical properties observed over SWA during the monsoon season and can be used in climate modelling studies and satellite retrievals. In particular and regarding the very high absorbing properties of biomass burning aerosols over SWA, our findings suggest that considering the effect of internal mixing on absorption properties of black carbon particles in climate models should help better assess the direct and semi-direct radiative effects of biomass burning particles.

scholarly journals Effects of biomass burning and photochemical oxidation on the black carbon mixing state and light absorption in summer season

2021 ◽  
Vol 248 ◽  
pp. 118230
Author(s):  
Tiantian Wang ◽  
Gang Zhao ◽  
Tianyi Tan ◽  
Ying Yu ◽  
Rongzhi Tang ◽  
...  
Keyword(s):  
Black Carbon ◽  
Biomass Burning ◽  
Light Absorption ◽  
Summer Season ◽  
Photochemical Oxidation ◽  
Mixing State
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