Molecular composition of organic aerosols in central Amazonia: An ultra-high-resolution mass spectrometry study
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Authors
Kourtchev, I
Godoi, RHM
Connors, S
Levine, JG
Godoi, AFL
Paralovo, SL
Barbosa, CGG
Souza, RAF
Manzi, AO
Seco, R
Sjostedt, S
Park, JH
Guenther, A
Kim, S
Smith, J
Martin, ST
Publication Date
2016-09-23Journal Title
Atmospheric Chemistry and Physics
ISSN
1680-7316
Publisher
Copernicus Publications
Volume
16
Issue
18
Pages
11899-11913
Language
English
Type
Article
This Version
VoR
Metadata
Show full item recordCitation
Kourtchev, I., Godoi, R., Connors, S., Levine, J., Archibald, A., Godoi, A., Paralovo, S., et al. (2016). Molecular composition of organic aerosols in central Amazonia: An ultra-high-resolution mass spectrometry study. Atmospheric Chemistry and Physics, 16 (18), 11899-11913. https://doi.org/10.5194/acp-16-11899-2016
Abstract
The Amazon Basin plays key role in atmospheric chemistry, biodiversity and climate change. In this study we applied nanoelectrospray (nanoESI) ultra-high-resolution mass spectrometry (UHRMS) for the analysis of the organic fraction of PM$_{2.5}$ aerosol samples collected during dry and wet seasons at a site in central Amazonia receiving background air masses, biomass burning and urban pollution. Comprehensive mass spectral data evaluation methods (e.g. Kendrick mass defect, Van Krevelen diagrams, carbon oxidation state and aromaticity equivalent) were used to identify compound classes and mass distributions of the detected species. Nitrogen-and/or sulfur-containing organic species contributed up to 60% of the total identified number of formulae. A large number of molecular formulae in organic aerosol (OA) were attributed to later-generation nitrogen-and sulfur-containing oxidation products, suggesting that OA composition is affected by biomass burning and other, potentially anthropogenic, sources. Isoprene-derived organosulfate (IEPOX-OS) was found to be the most dominant ion in most of the analysed samples and strongly followed the concentration trends of the gas-phase anthropogenic tracers confirming its mixed anthropogenic-biogenic origin. The presence of oxidised aromatic and nitro-aromatic compounds in the samples suggested a strong influence from biomass burning especially during the dry period. Aerosol samples from the dry period and under enhanced biomass burning conditions contained a large number of molecules with high carbon oxidation state and an increased number of aromatic compounds compared to that from the wet period. The results of this work demonstrate that the studied site is influenced not only by biogenic emissions from the forest but also by biomass burning and potentially other anthropogenic emissions from the neighbouring urban environments.
Sponsorship
Research at the University of Cambridge was supported by European Research Council grant no. 279405. The authors would like to thank Jason Surratt (University of North Carolina) for providing a synthesised IEPOX-OS standard. O3, CO, NOy , RH and rain data were obtained from the Atmospheric Radiation Measurement (ARM) Climate Research Facility, a U.S. Department of Energy (grant DE-SC0011122) Office of Science user facility sponsored by the Office of Biological and Environmental Research. We acknowledge the support from the Central Office of the Large Scale Biosphere Atmosphere Experiment in Amazonia (LBA), the Instituto Nacional de Pesquisas da Amazonia (INPA), and the Universidade do Estado do Amazonia (UEA). The work was conducted under 001030/2012-4 of the Brazilian National Council for Scientific and Technological Development (CNPq).
Funder references
National Centre for Atmospheric Science (NERC) (via University of Leeds) (R8/H12/83/003)
National Centre for Atmospheric Science (NERC) (via University of Leeds) (R8/H12/83/003)
National Centre for Atmospheric Science (NERC) (via University of Leeds) (R8H12/83/009)
European Research Council (279405)
Identifiers
External DOI: https://doi.org/10.5194/acp-16-11899-2016
This record's URL: https://www.repository.cam.ac.uk/handle/1810/261130
Rights
Attribution 4.0 International, Attribution 4.0 International, Attribution 4.0 International, Attribution 4.0 International