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

2017 ◽  
Author(s):  
Xiaole Pan ◽  
Yugo Kanaya ◽  
Fumikazu Taketani ◽  
Takuma Miyakawa ◽  
Satoshi Inomata ◽  
...  
Keyword(s):  
Black Carbon ◽  
Biomass Burning ◽  
Regional Climate ◽  
High Temporal Resolution ◽  
Equivalent Diameter ◽  
Emission Characteristics ◽  
Gaussian Shape ◽  
Essential Information ◽  
Average Mass ◽  
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 open burning of wheat straw and rape plants, which are the main crops cultivated in the Yangtze River Delta region of China. A single particle soot photometer (SP2) was adopted 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 perfect Gaussian shape with an average mass equivalent diameter (MED) of 189 nm (the measured MED values varied between 152 nm and 215 nm), assuming an rBC density of 1.8 g/cm3. rBC particles less than 80 nm in size (the lower detection limit of the SP2) accounted for only ~ 5 % of the total rBC mass, on average. The emission ratios, which are expressed as ∆rBC/∆CO (∆ indicates the difference between the observed and background values), displayed a significant positive correlation with the MCE values and varied between 1.8–34 ng/m3/ppbv. Multi-peak fitting analysis of the delay time (∆t, 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 ∆t = 1.7 μs and ∆t = 3.2 μs, which could be attributed to the contributions from both flaming and smoldering combustion in each burning case. Both the ∆t 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 study highlights that open biomass burning produces the majority of coated rBC particles, which have considerable ability to affect cloud processes and influence regional climate.

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 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

Enhanced light absorption due to the mixing state of black carbon in fresh biomass burning emissions

2018 ◽  
Vol 180 ◽  
pp. 184-191 ◽  
Author(s):  
Qiyuan Wang ◽  
Junji Cao ◽  
Yongming Han ◽  
Jie Tian ◽  
Yue Zhang ◽  
...  
Keyword(s):  
Black Carbon ◽  
Biomass Burning ◽  
Light Absorption ◽  
Mixing State ◽  
Fresh Biomass

scholarly journals Measurements to determine the mixing state of black carbon emitted from the 2017–2018 California wildfires and urban Los Angeles

2020 ◽  
Vol 20 (24) ◽  
pp. 15635-15664
Author(s):  
Joseph Ko ◽  
Trevor Krasowsky ◽  
George Ban-Weiss
Keyword(s):  
Los Angeles ◽  
Black Carbon ◽  
Biomass Burning ◽  
Spatial Scales ◽  
Field Measurements ◽  
Mixing State ◽  
Air Masses ◽  
Microphysical Properties ◽  
Source Type ◽  
Wide Variability

Abstract. The effects of atmospheric black carbon (BC) on climate and public health have been well established, but large uncertainties remain regarding the extent of the impacts of BC at different temporal and spatial scales. These uncertainties are largely due to the heterogeneous nature of BC in terms of its spatiotemporal distribution, mixing state, and coating composition. Here, we seek to further understand the size and mixing state of BC emitted from various sources and aged over different timescales using field measurements in the Los Angeles region. We measured refractory black carbon (rBC) with a single-particle soot photometer (SP2) on Catalina Island, California (∼70 km southwest of downtown Los Angeles) during three different time periods. During the first campaign (September 2017), westerly winds were dominant and measured air masses were representative of well-aged background over the Pacific Ocean. In the second and third campaigns (December 2017 and November 2018, respectively), atypical Santa Ana wind conditions allowed us to measure biomass burning rBC (BCbb) from air masses dominated by large biomass burning events in California and fossil fuel rBC (BCff) from the Los Angeles Basin. We observed that the emissions source type heavily influenced both the size distribution of the rBC cores and the rBC mixing state. BCbb had thicker coatings and larger core diameters than BBff. We observed a mean coating thickness (CTBC) of ∼40–70 nm and a count mean diameter (CMD) of ∼120 nm for BCbb. For BCff, we observed a CTBC of ∼5–15 nm and a CMD of ∼100 nm. Our observations also provided evidence that aging led to an increased CTBC for both BCbb and BCff. Aging timescales < ∼1 d were insufficient to thickly coat freshly emitted BCff. However, CTBC for aged BCff within aged background plumes was ∼35 nm thicker than CTBC for fresh BCff. Likewise, we found that CTBC for aged BCbb was ∼18 nm thicker than CTBC for fresh BCbb. The results presented in this study highlight the wide variability in the BC mixing state and provide additional evidence that the emissions source type and aging influence rBC microphysical properties.

scholarly journals Effects of mixing state on optical and radiative properties of black carbon in the European Arctic

2018 ◽  
Author(s):  
Marco Zanatta ◽  
Paolo Laj ◽  
Martin Gysel ◽  
Urs Baltensperger ◽  
Stergios Vratolis ◽  
...  
Keyword(s):  
Black Carbon ◽  
Radiative Forcing ◽  
Particle Diameter ◽  
Arctic Region ◽  
Climate Impacts ◽  
Radiative Properties ◽  
The Arctic ◽  
Absorption Enhancement ◽  
Equivalent Diameter ◽  
Mixing State

Abstract. Atmospheric aging promotes internal mixing of black carbon (BC) leading to an enhancement of light absorption and radiative forcing. The relationship between BC mixing state and consequent absorption enhancement was never estimated for BC found in the Arctic region. In the present work, we aim to quantify the absorption enhancement and its impact on radiative forcing as a function of microphysical properties and mixing state of BC observed in-situ at the Zeppelin Arctic station (78° N) in the spring of 2012 during the CLIMSLIP (Climate impacts of short-lived pollutants in the Arctic) project. Single particle soot photometer (SP2) measurements showed a mean mass concentration of refractory black carbon (rBC) of 39 ng m−3, while the rBC mass size distribution was of log-normal shape peaking at an rBC mass equivalent diameter (DrBC) of around 240 nm. On average, the number fraction of particles containing a BC core with DrBC > 80 nm was less than 5 % in the size range (overall optical particle diameter) from 150–500 nm. The BC cores were internally mixed with other particulate matter. The median coating thickness of BC cores with 220 nm 

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
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