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  Water-soluble organic compounds in biomass burning aerosols over Amazonia: 2. Apportionment of the chemical composition and importance of the polyacidic fraction

Mayol-Bracero, O. L., Guyon, P., Graham, B., Roberts, G., Andreae, M. O., Decesari, S., et al. (2002). Water-soluble organic compounds in biomass burning aerosols over Amazonia: 2. Apportionment of the chemical composition and importance of the polyacidic fraction. Journal of Geophysical Research, 107(D20): 8091. doi:10.1029/2001JD000522.

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Genre: Journal Article
Alternative Title : J. Geophys. Res.

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 Creators:
Mayol-Bracero, O. L.1, Author           
Guyon, P.1, Author           
Graham, B.1, Author           
Roberts, G.1, Author           
Andreae, M. O.1, Author           
Decesari, S., Author
Facchini, M. C., Author
Fuzzi, S., Author
Artaxo, P., Author
Affiliations:
1Biogeochemistry, Max Planck Institute for Chemistry, Max Planck Society, ou_1826286              

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Free keywords: water soluble organic compounds; biomass burning; carbonaceous aerosols; chemical characterization; Amazonia
 Abstract: Chemical characterization was performed on carbonaceous aerosols from Rondonia in the Brazilian Amazon region as part of the European contribution to the Large-Scale Biosphere- Atmosphere Experiment in Amazonia (LBA-EUSTACH). The sampling period (October 1999) included the peak of the burning season as well as the dry-to-wet season transition. Characterization of the carbonaceous material was performed by using a thermal combustion method. This enabled determination of aerosol total carbon (TC), black carbon (BC), and organic carbon (OC). A significant fraction of the BC material (on average about 50%) seemed to be highly refractory organic material soluble in water. A more detailed analysis of the water-soluble organic carbon (WSOC) fraction of the TC was undertaken, involving measurements of WSOC content, high-performance liquid chromatography (HPLC) separation (with UV detection) of the water-soluble components, and characterization of individual components by gas chromatography/mass spectrometry (GC/MS). The WSOC fraction accounted for 45-75% of the OC. This high WSOC fraction suggests an aerosol derived mainly from smoldering combustion. Using GC/MS, many different compounds, containing hydroxy, carboxylate, and carbonyl groups, were detected. The fraction of the WSOC identified by GC/MS was about 10%. Three classes of compounds were separated by HPLC/UV: neutral compounds (N), monocarboxylic and dicarboxylic acids (MDA), and polycarboxylic acids (PA). The sum of these three groups accounted for about 70% of the WSOC, with MDA and PA being most abundant (about 50%). Good correlations (r(2) between 0.84 and 0.99) of BCwater (BC after water extraction) and levoglucosan (both indicators of biomass combustion) with the water-soluble species (i.e., WSOC, N, MDA, and PA), and their increase in concentrations during the burning period provided strong evidence that biomass burning is a major source of the WSOC. Particularly interesting is that PA and therefore, probably, humic-like substances (due to their polyacidic nature) are generated in significant amounts during biomass burning. These substances, due to their water solubility and surface tension- lowering effects, may play an important role in determining the overall cloud condensation nuclei activity of biomass burning aerosols and, consequently, could be important in cloud processes and climate forcing.

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Language(s): eng - English
 Dates: 2002-09
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: eDoc: 18231
ISI: 000180466200116
DOI: 10.1029/2001JD000522
 Degree: -

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Title: Journal of Geophysical Research
  Alternative Title : J. Geophys. Res.
Source Genre: Journal
 Creator(s):
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Publ. Info: -
Pages: - Volume / Issue: 107 (D20) Sequence Number: 8091 Start / End Page: - Identifier: ISSN: 0747-7309