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| Titel |
Size distributions and temporal variations of biological aerosol particles in the Amazon rainforest characterized by microscopy and real-time UV-APS fluorescence techniques during AMAZE-08 |
| VerfasserIn |
J. A. Huffman, B. Sinha, R. M. Garland, A. Snee-Pollmann, S. S. Gunthe, P. Artaxo, S. T. Martin, M. O. Andreae, U. Pöschl |
| 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 ; 12, no. 24 ; Nr. 12, no. 24 (2012-12-18), S.11997-12019 |
| Datensatznummer |
250011676
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| Publikation (Nr.) |
 copernicus.org/acp-12-11997-2012.pdf |
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| Zusammenfassung |
| As a part of the AMAZE-08 campaign during the wet season in the rainforest
of central Amazonia, an ultraviolet aerodynamic particle sizer (UV-APS) was
operated for continuous measurements of fluorescent biological aerosol
particles (FBAP). In the coarse particle size range
(> 1 μm) the campaign median and quartiles of FBAP number and mass concentration
were 7.3 × 104 m−3 (4.0–13.2 × 104 m−3) and
0.72 μg m−3 (0.42–1.19 μg m−3), respectively,
accounting for 24% (11–41%) of total particle number and 47%
(25–65%) of total particle mass. During the five-week campaign in
February–March 2008 the concentration of coarse-mode Saharan dust particles
was highly variable. In contrast, FBAP concentrations remained fairly
constant over the course of weeks and had a consistent daily pattern,
peaking several hours before sunrise, suggesting observed FBAP was dominated
by nocturnal spore emission. This conclusion was supported by the consistent
FBAP number size distribution peaking at 2.3 μm, also attributed to
fungal spores and mixed biological particles by scanning electron microscopy
(SEM), light microscopy and biochemical staining. A second primary
biological aerosol particle (PBAP) mode between 0.5 and 1.0 μm was
also observed by SEM, but exhibited little fluorescence and no true fungal
staining. This mode may have consisted of single bacterial cells,
brochosomes, various fragments of biological material, and small
Chromalveolata (Chromista) spores. Particles liquid-coated with mixed
organic-inorganic material constituted a large fraction of observations, and
these coatings contained salts likely from primary biological origin. We
provide key support for the suggestion that real-time laser-induce
fluorescence (LIF) techniques using 355 nm excitation provide size-resolved
concentrations of FBAP as a lower limit for the atmospheric abundance of
biological particles in a pristine environment. We also show some
limitations of using the instrument for ambient monitoring of weakly
fluorescent particles < 2 μm. Our measurements confirm that
primary biological particles, fungal spores in particular, are an important
fraction of supermicron aerosol in the Amazon and that may contribute
significantly to hydrological cycling, especially when coated by mixed
inorganic material. |
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