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Composition and diurnal variability of the natural Amazonian aerosol

Graham, Bim and Guyon, Pascal and Maenhaut, Willy and Taylor, Philip E. and Ebert, Martin and Matthias-Maser, Sabine and Mayol-Bracero, Olga L. and Godoi, Ricardo H. M. and Artaxo, Paulo and Meixner, Franz X. and Lima Moura, Marcos A. and Eça D'Almeida Rocha, Carlos H. and Van Grieken, René and Glovsky, M. Michael and Flagan, Richard C. and Andreae, Meinrat O. (2003) Composition and diurnal variability of the natural Amazonian aerosol. Journal of Geophysical Research D, 108 (D24). Art. No. 4765. ISSN 0148-0227. doi:10.1029/2003JD004049.

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As part of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA)-Cooperative LBA Airborne Regional Experiment (CLAIRE) 2001 campaign, separate day and nighttime aerosol samples were collected in July 2001 at a ground-based site in Amazonia, Brazil, in order to examine the composition and temporal variability of the natural “background” aerosol. A combination of analytical techniques was used to characterize the elemental and ionic composition of the aerosol. Major particle types larger than ∼0.5 μm were identified by electron and light microscopy. Both the coarse and fine aerosol were found to consist primarily of organic matter (∼70 and 80% by mass, respectively), with the coarse fraction containing small amounts of soil dust and sea-salt particles and the fine fraction containing some non-sea-salt sulfate. Coarse particulate mass concentrations (CPM ≈ PM_(10) − PM_2) were found to be highest at night (average = 3.9 ± 1.4 μg m^(−3), mean night-to-day ratio = 1.9 ± 0.4), while fine particulate mass concentrations (FPM ≈ PM_2) increased during the daytime (average = 2.6 ± 0.8 μg m^(−3), mean night-to-day ratio = 0.7 ± 0.1). The nocturnal increase in CPM coincided with an increase in primary biological particles in this size range (predominantly yeasts and other fungal spores), resulting from the trapping of surface-derived forest aerosol under a shallow nocturnal boundary layer and a lake-land breeze effect at the site, although active nocturnal sporulation may have also contributed. Associated with this, we observed elevated nighttime concentrations of biogenic elements and ions (P, S, K, Cu, Zn, NH_4^+) in the CPM fraction. For the FPM fraction a persistently higher daytime concentration of organic carbon was found, which indicates that photochemical production of secondary organic aerosol from biogenic volatile organic compounds may have made a significant contribution to the fine aerosol. Dust and sea-salt-associated elements/ions in the CPM fraction, and non-sea-salt sulfate in the FPM fraction, showed higher daytime concentrations, most likely due to enhanced convective downward mixing of long-range transported aerosol.

Item Type:Article
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URLURL TypeDescription
Maenhaut, Willy0000-0002-4715-4627
Flagan, Richard C.0000-0001-5690-770X
Andreae, Meinrat O.0000-0003-1968-7925
Additional Information:Copyright 2003 by the American Geophysical Union. Received 5 August 2003; revised 5 October 2003; accepted 23 October 2003; published 18 December 2003. This study was carried out as part of the Large-Scale Atmosphere-Biosphere Experiment in Amazonia (LBA). It was made possible by fundamental support through the Max Planck Society. P. Artaxo acknowledges financial support from “Fundação de Amparo à Pesquisa do Estado de São Paulo”, W. Maenhaut acknowledges financial support from the Belgian Federal Office for Scientific, Technical and Cultural Affairs, and the “Fonds voor Wetenschappelijk Onderzoek-Vlaanderen”, and P. Taylor, R. Flagan and M. Glovsky acknowledge support from the Philip Morris External Research Program. We acknowledge X. Chi for the thermooptical transmission measurements, and sincerely thank the staff of Manaus Energia who supported us in the course of the measurements through the supply and maintenance of infrastructure.
Funding AgencyGrant Number
Max Planck SocietyUNSPECIFIED
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)UNSPECIFIED
Belgian Federal Science Policy Office (BELSPO)UNSPECIFIED
Fonds Wetenschappelijk Onderzoek - Vlaanderen (FWO)UNSPECIFIED
Philip Morris External Research ProgramUNSPECIFIED
Subject Keywords:biogenic aerosol; spores; elemental composition; Amazon; bioaerosol; organic aerosol
Issue or Number:D24
Classification Code:0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions; 0322 Atmospheric Composition and Structure: Constituent sources and sinks; 0365 Atmospheric Com
Record Number:CaltechAUTHORS:20141027-135717698
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Official Citation:Graham, B., et al. (2003), Composition and diurnal variability of the natural Amazonian aerosol, J. Geophys. Res., 108, 4765, doi:10.1029/2003JD004049, D24.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50871
Deposited By: George Porter
Deposited On:27 Oct 2014 21:21
Last Modified:10 Nov 2021 19:02

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