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| Titel |
Water uptake and chemical composition of fresh aerosols generated in open burning of biomass |
| VerfasserIn |
C. M. Carrico, M. D. Petters, S. M. Kreidenweis, A. P. Sullivan, G. R. McMeeking, E. J. T. Levin, G. Engling, W. C. Malm, J. L. Collett |
| 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 ; 10, no. 11 ; Nr. 10, no. 11 (2010-06-10), S.5165-5178 |
| Datensatznummer |
250008522
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| Publikation (Nr.) |
 copernicus.org/acp-10-5165-2010.pdf |
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| Zusammenfassung |
| As part of the Fire Lab at Missoula Experiments (FLAME) in 2006–2007, we
examined hygroscopic properties of particles emitted from open combustion of
33 select biomass fuels. Measurements of humidification growth factors for
subsaturated water relative humidity (RH) conditions were made with a
hygroscopic tandem differential mobility analyzer (HTDMA) for dry particle
sizes of 50, 100 and 250 nm. Results were then fit to a single-parameter
model to obtain the hygroscopicity parameter, κ. Particles in
freshly emitted biomass smoke exhibited a wide range of hygroscopicity
(individual modes with 0<κ<1.0), spanning a range from the
hygroscopicity of fresh diesel soot emissions to that of pure inorganic
salts commonly found in the ambient aerosol. Smoke aerosols dominated by
carbonaceous species typically had a unimodal growth factor with
corresponding mean κ=0.1 (range of 0<κ<0.4). Those
with a substantial inorganic mass fraction typically separated into less-
and more-hygroscopic modes at high RH, the latter with mean κ=0.4
(range of 0.1<κ<1). The bimodal κ distributions were
indicative of smoke chemical heterogeneity at a single particle size,
whereas heterogeneity as a function of size was indicated by typically
decreasing κ values with increasing dry particle diameters.
Hygroscopicity varied strongly with biomass fuel type and, to a lesser
extent, with combustion conditions. Among the most hygroscopic smokes were
those from palmetto, rice straw, and sawgrass, while smoke particles from
coniferous species such as spruces, firs, pines, and duffs were among the
least hygroscopic. Overall, hygroscopicity decreased with increasing ratios
of total carbon to inorganic ions as measured in PM2.5 filter samples.
Despite aerosol heterogeneity, reconstructions of κ using PM2.5
bulk chemical composition data fell along a 1:1 line with measured ensemble
κ values. |
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