Size-resolved chemical composition, effective density, and optical properties of biomass burning particles
Biomass burning aerosol has an important impact on the global radiative budget. A better understanding of the correlations between the mixing states of biomass burning particles and their optical properties is the goal of a number of current studies. In this work, the effective density, chemical...
Main Authors: | , , , , , , , |
---|---|
Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2017-06-01
|
Series: | Atmospheric Chemistry and Physics |
Online Access: | http://www.atmos-chem-phys.net/17/7481/2017/acp-17-7481-2017.pdf |
Summary: | Biomass burning aerosol has an important impact on the global radiative
budget. A better understanding of the correlations between the mixing states
of biomass burning particles and their optical properties is the goal of a
number of current studies. In this work, the effective density, chemical
composition, and optical properties of rice straw burning particles in the
size range of 50–400 nm were measured using a suite of online methods. We
found that the major components of particles produced by burning rice straw
included black carbon (BC), organic carbon (OC), and potassium salts, but the
mixing states of particles were strongly size dependent. Particles of 50 nm
had the smallest effective density (1.16 g cm<sup>−3</sup>) due to a relatively
large proportion of aggregate BC. The average effective densities of
100–400 nm particles ranged from 1.35 to 1.51 g cm<sup>−3</sup> with OC and
inorganic salts as dominant components. Both density distribution and
single-particle mass spectrometry showed more complex mixing states in larger
particles. Upon heating, the separation of the effective density distribution
modes confirmed the external mixing state of less-volatile BC or soot and
potassium salts. The size-resolved optical properties of biomass burning
particles were investigated at two wavelengths (<i>λ</i> = 450 and
530 nm). The single-scattering albedo (SSA) showed the lowest value for
50 nm particles (0.741 ± 0.007 and 0.889 ± 0.006) because of the
larger proportion of BC content. Brown carbon played an important role for
the SSA of 100–400 nm particles. The Ångström absorption exponent
(AAE) values for all particles were above 1.6, indicating the significant
presence of brown carbon in all sizes. Concurrent measurements in our work
provide a basis for discussing the physicochemical properties of biomass
burning aerosol and its effects on the global climate and atmospheric
environment. |
---|---|
ISSN: | 1680-7316 1680-7324 |