10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Light Absorption by Organic Aerosol from Combustion and Pyrolysis of Fir in Southern China
RANRAN ZHAO, Yongming Zhang, Feng Wang, Qixing Zhang, University of Science and Technology of China
Abstract Number: 764 Working Group: Carbonaceous Aerosol
Abstract Biomass burning, including forest wildfires, residential heating and cooking, is an important source of light absorbing organic aerosols (OA). In this work, we performed a laboratory study of light absorption properties of OA from combustion of fir, which is a common tree species in southern China. Different moisture content of fir wood pieces were heated in air and nitrogen in a tube furnace under finely controlled temperature. Sampling filters were extracted with deionized water and methanol. The optical properties of water soluble organic carbon (WSOC) and methanol soluble organic carbon (MSOC) were analyzed and characterized by calculation of the absorption per mass, the imaginary part of the refractive index, and the Ångström absorption exponent (AAE). We compared the results obtained from fir pyrolysis in nitrogen with those obtained from pyrolysis of oak and pine1 and corn stalk2. The results show that the absorption per mass of WSOC obtained from fir pyrolysis generated at 270 ℃ is similar to that of oak , about 1.1m2 / g at 360nm. In addition, the absorption per mass of MSOC obtained from fir pyrolysis at 360 nm is similar to that of oak and pine, but slightly higher than that of corn stalk. The fuel structure leads to the discrepancy. The AAE value of fir range from 7.2 to 7.8 in the range of 380nm to 460nm, similar to that of pine, oak and corn stalk. The results also show the differences between OA from fir combustion in air and pyrolysis in nitrogen. OA produced by combustion of fir in the air has stronger light absorption in the UV region than that in the nitrogen. However, the result is opposite near the visible region. The differences could be attributed to the different thermal decomposition rate of volatiles during combustion and pyrolysis and the large amounts of black carbon (BC) generated during the combustion process. The details of this discrepancy will also be discussed.
1.Chen, Y.; Bond, T. C., Light absorption by organic carbon from wood combustion. Atmospheric Chemistry and Physics 2010, 4, (10), 1773-1787. 2.Li, X.; Chen, Y.; Bond, T. C., Light absorption of organic aerosol from pyrolysis of corn stalk. Atmospheric Environment 2016, 144, 249-256.