Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 13001-13016, 2017
https://doi.org/10.5194/acp-17-13001-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
06 Nov 2017
Emission characteristics of refractory black carbon aerosols from fresh biomass burning: a perspective from laboratory experiments
Xiaole Pan1, Yugo Kanaya2, Fumikazu Taketani2, Takuma Miyakawa2, Satoshi Inomata3, Yuichi Komazaki2, Hiroshi Tanimoto3, Zhe Wang1,4, Itsushi Uno4, and Zifa Wang1 1State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China
2Japan Agency for Marine-Earth Science and Technology, Yokohama, 236-0001, Japan
3National Institute for Environmental Studies, Tsukuba, 305-8506, Japan
4Research Institute for Applied Mechanics, Kyushu University, Kasuga, 816-8580, Japan
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.

Citation: Pan, X., Kanaya, Y., Taketani, F., Miyakawa, T., Inomata, S., Komazaki, Y., Tanimoto, H., Wang, Z., Uno, I., and Wang, Z.: Emission characteristics of refractory black carbon aerosols from fresh biomass burning: a perspective from laboratory experiments, Atmos. Chem. Phys., 17, 13001-13016, https://doi.org/10.5194/acp-17-13001-2017, 2017.
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Short summary
Characteristics of refractory black carbon (rBC) from open biomass burning (OBB) have a great impact on regional pollution and climate, in particular in East Asia. However, experimental study on characteristics of rBC from agricultural residue burning in East China was limited. This study performed laboratory experiments: we found that emission of rBC is highly related to flaming burning, and non-rBC to smoldering burning. Rapid condensation of semi-volatile organics resulted in coated rBC.
Characteristics of refractory black carbon (rBC) from open biomass burning (OBB) have a great...
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