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| Titel |
Reduction in biomass burning aerosol light absorption upon humidification: roles of inorganically-induced hygroscopicity, particle collapse, and photoacoustic heat and mass transfer |
| VerfasserIn |
K. A. Lewis, W. P. Arnott, H. Moosmüller, R. K. Chakrabarty, C. M. Carrico, S. M. Kreidenweis, D. E. Day, W. C. Malm, A. Laskin, J. L. Jimenez, I. M. Ulbrich, J. A. Huffman, T. B. Onasch, A. Trimborn, L. Liu, M. I. Mishchenko |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 22 ; Nr. 9, no. 22 (2009-11-27), S.8949-8966 |
| Datensatznummer |
250007770
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| Publikation (Nr.) |
 copernicus.org/acp-9-8949-2009.pdf |
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| Zusammenfassung |
| Smoke particle emissions from the combustion of biomass fuels typical for
the western and southeastern United States were studied and compared under
high humidity and ambient conditions in the laboratory. The fuels used were
Montana ponderosa pine (Pinus ponderosa), southern California chamise
(Adenostoma fasciculatum), and Florida saw
palmetto (Serenoa repens). Information on the non-refractory chemical composition of
biomass burning aerosol from each fuel was obtained with an aerosol mass
spectrometer and through estimation of the black carbon concentration from
light absorption measurements at 870 nm. Changes in the optical and physical
particle properties under high humidity conditions were observed for
hygroscopic smoke particles containing substantial inorganic mass fractions
that were emitted from combustion of chamise and palmetto fuels. Light
scattering cross sections increased under high humidity for these particles,
consistent with the hygroscopic growth measured for 100 nm particles in
HTDMA measurements. Photoacoustic measurements of aerosol light absorption
coefficients revealed a 20% reduction with increasing relative humidity,
contrary to the expectation of light absorption enhancement by the liquid
coating taken up by hygroscopic particles. This reduction is hypothesized to
arise from two mechanisms: (1) shielding of inner monomers after particle
consolidation or collapse with water uptake; (2) the lower case contribution of mass
transfer through evaporation and condensation at high relative humidity (RH) to
the usual heat transfer pathway for energy release by laser-heated particles
in the photoacoustic measurement of aerosol light absorption. The mass
transfer contribution is used to evaluate the fraction of aerosol surface
covered with liquid water solution as a function of RH. |
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