Impact of Combustion Efficiency of Open Biomass Burning on the Mixing State of Black Carbon Containing Particles

Xiaole PAN, Kyushu University, Fukuoka, Japan, Yugo Kanaya, JAMSTEC Japan Agency for Marine-Earth Science and Technology, Japan Agency for Marine-Earth Science and Technology, 3173-25, Showa-machi, Kanazawa-ku, Yokohama, Kanagawa 236-0001, Japan, Tel: +81-45-778-5365, Fax: +81-45-778-5706, Kanagawa, Japan, Fumikazu Taketani, Japan Agency for Marine-Earth Science and Technology, RIGC, Yokosuka, Japan, Takuma Miyakawa, Japan Agency for Marine-Earth Science and Technology, Research Institute for Global Change, Kanagawa, Japan, Satoshi Inomata, National Institute for Environmental Studies (NIES), Tsukuba, Japan, Yuichi Komazaki, JAMSTEC Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan, Hiroshi Tanimoto, National Institute of Environmental Studies, Ibaraki, Japan, Itsushi Uno, Research Institute for Applied Mechanics, Kyushu University, Fukuoka, Japan and Zifa Wang, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
Abstract:
Open biomass burning (OBB) experiments were performed in the laboratory environment to investigate the mixing state of refractory black carbon (rBC) in fresh smoke and its dependence on combustion state. A Single-Particle Soot Photometer (SP2) was adopted to measure variation of number size distribution of rBC-containing particles in high temporal resolution. General combustion state of each OBB case was indicated by modified combustion efficiency (MCE) using accumulated enhancement of mixing ratios of carbon dioxide and carbon monoxide during the experiments. We found that mass equivalent diameter (MED) of rBC increased apparently with increase of MCE values, indicating the flaming-dominant combustion tend to produce the rBC particles with relative larger size, probably because of coagulation processes in high concentration condition. Coating thickness of rBC-containing particle was calculated by leading edge only fitting (LEO-fitting) method. In the present study we defined the rBC-containing particles with shell/core (S/C) ratio larger than 2 as “thickly coated” and that less then 1.5 as “thinly coated”. As a result, thickly coated rBC particles normally had a relatively small core (MED of rBC less than 150 nm) and its number fraction showed an evident decrease as a function of MCE value, whereas, larger rBC particles (MED larger than 150 nm) were normally thinly coated. Number fraction of both thinly coated and uncoated rBC particles had an positive correlation with MCE value. Substantial amount of light scattering particles (LSP) observed in the smoldering-dominant OBB plumes could partially explain the increase of number fraction of coated rBC particles. ∆rBC/∆CO ratio showed a good positive correlation with MCE with an average value of 16.8 (1.2 – 51.6) ng/m3/ppbv, and ∆rBC/∆CO2 ratio was found 628.7 ng/m3/ppmv, generally consistent with previous studies.
Back to: Biomass Burning Impacts on Composition, Clouds, and Climate: SEAC4RS, BBOP, SAMBBA, BORTAS, FLAME-4, and Other Recent Studies III Posters