Abstract:
[1] As part of the European contribution to the Large-Scale Atmosphere-Biosphere Experiment in Amazonia (LBA-EUSTACH), aerosols were sampled at representative pasture and primary rainforest sites in Rondonia, Brazil, during the 1999 "burning season" and dry-to-wet season transition (September-October). Water-soluble organic compounds (WSOCs) within the samples were characterized using a combination of H-1 Nuclear Magnetic Resonance (NMR) spectroscopy for chemical functional group analysis, and Gas Chromatography-Mass Spectrometry (GC-MS) for identification and quantification of individual low-molecular-weight compounds. The H-1 NMR analysis indicates that WSOCs are predominantly aliphatic or oxygenated aliphatic compounds (alcohols, carboxylic acids, etc.), with a minor content of aromatic rings carrying carboxylic and phenolic groups. Levoglucosan (1,6-anhydro-beta-D-glucose), a well-known cellulose combustion product, was the most abundant individual compound identified by GC-MS (0.04-6.90 mug m(-3)), accounting for 1-6% of the total carbon (TC) and 2-8% of the water-soluble organic carbon (WSOC). Other anhydrosugars, produced by hemicellulose breakdown, were detected in much smaller amounts, in addition to series of acids, hydroxyacids, oxoacids, and polyalcohols (altogether 2-5% of TC, 3-6% of WSOC). Most correlated well with organic carbon, black carbon, and potassium, indicating biomass burning to be the major source. A series of sugar alcohols (mannitol, arabitol, erythritol) and sugars (glucose, fructose, mannose, galactose, sucrose, trehalose) were identified as part of the natural background aerosol and are probably derived from airborne microbes and other biogenic material. The bulk of the WSOCs (86-91% WSOC) eluded analysis by GC-MS and may be predominantly high-molecular weight in nature.

Author Keywords:
organic aerosols, biomass burning, GC-MS, NMR, levogluosan, Amazon

KeyWords Plus:
AIRBORNE PARTICULATE MATTER, CONDENSATION NUCLEUS ACTIVITY, GAS-LIQUID-CHROMATOGRAPHY, HUMIC-LIKE SUBSTANCES, LONG-RANGE TRANSPORT, DICARBOXYLIC-ACIDS, ATMOSPHERIC AEROSOL, SACCHAROMYCES-CEREVISIAE, CHEMICAL-COMPOSITION, THERMAL-DEGRADATION

Addresses:
Graham B, CSIRO Atmospher Res, PMBI Aspendale, Vic 3195, Australia
CSIRO Atmospher Res, PMBI Aspendale, Vic 3195, Australia
Univ Puerto Rico, Inst Trop Ecosyst Studies, Rio Piedras, PR 00931 USA
Max Planck Inst Chem, Dept Biogeochem, D-55020 Mainz, Germany
Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA
CNR, Inst Atmospher & Ocean Sci, I-40129 Bologna, Italy
Univ Sao Paulo, Inst Phys, BR-05315970 Sao Paulo, Brazil
State Univ Ghent, Inst Nucl Sci, B-9000 Ghent, Belgium
Univ Oldenburg, Fachbereich Chem FB9, Dept Chem, D-26111 Oldenburg, Germany

Publisher:
AMER GEOPHYSICAL UNION, 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA

IDS Number:
636PY

ISSN:
0747-7309