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Title: Isoprene photo-oxidation products quantify the effect of pollution on hydroxyl radicals over Amazonia

Abstract

Nitrogen oxides (NO x) emitted from human activities are believed to regulate the atmospheric oxidation capacity of the troposphere. However, observational evidence is limited for the low-to-median NO x concentrations prevalent outside of polluted regions. Directly measuring oxidation capacity, represented primarily by hydroxyl radicals (OH), is challenging, and the span in NO x concentrations at a single observation site is often not wide. Concentrations of isoprene and its photo-oxidation products were used to infer the equivalent noontime OH concentrations. The fetch at an observation site in central Amazonia experienced varied contributions from background regional air, urban pollution, and biomass burning. The afternoon concentrations of reactive nitrogen oxides (NO y), indicative of NO x exposure during the preceding few hours, spanned from 0.3 to 3.5 parts per billion. Accompanying the increase of NO y concentration, the inferred equivalent noontime OH concentrations increased by at least 250% from 0.6 × 10 6 to 1.6 × 10 6 cm -3. The conclusion is that, compared to background conditions of low NO x concentrations over the Amazon forest, pollution increased NO x concentrations and amplified OH concentrations, indicating the susceptibility of the atmospheric oxidation capacity over the forest to anthropogenic influence and reinforcing themore » important role of NO x in sustaining OH concentrations.« less

Authors:
ORCiD logo [1]; ORCiD logo [2];  [2]; ORCiD logo [2]; ORCiD logo [3];  [4]; ORCiD logo [5]; ORCiD logo [5]; ORCiD logo [6]; ORCiD logo [7]; ORCiD logo [8]; ORCiD logo [9]
  1. Harvard Univ., Cambridge, MA (United States). School of Engineering and Applied Sciences (SEAS)
  2. Univ. of California, Irvine, CA (United States). Dept. of Earth System Science
  3. Univ. of California, Berkeley, CA (United States). Dept. of Environmental Science, Policy, and Management
  4. Harvard Univ., Cambridge, MA (United States). School of Engineering and Applied Sciences (SEAS) and Dept. of Chemistry and Chemical Biology
  5. Brookhaven National Lab. (BNL), Upton, NY (United States). Dept. of Environmental and Climate Sciences
  6. Univ. of Sao Paulo (Brazil). Dept. of Applied Physics
  7. Amazonas State Univ., Manaus (Brazil). Dept. of Meterology
  8. Harvard Univ., Cambridge, MA (United States). School of Engineering and Applied Sciences (SEAS); Colby College, Waterville, ME (United States). Dept. of Chemistry
  9. Harvard Univ., Cambridge, MA (United States). School of Engineering and Applied Sciences (SEAS) and Dept. of Earth and Planetary Sciences
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA); National Inst. of Amazonian Research (INPA); Amazonas State Univ., Manaus (Brazil); National Council for Scientific and Technological Development (CNPq); National Science Foundation (NSF); São Paulo Research Foundation (FAPESP)
OSTI Identifier:
1433944
Report Number(s):
BNL-203529-2018-JAAM
Journal ID: ISSN 2375-2548
Grant/Contract Number:
SC0012704; 001030/2012-4; SC0011115; SC0011122; 1628491; 1321987; 2014/05014-0; 2017/17047-0
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Science Advances
Additional Journal Information:
Journal Volume: 4; Journal Issue: 4; Journal ID: ISSN 2375-2548
Publisher:
AAAS
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Liu, Yingjun, Seco, Roger, Kim, Saewung, Guenther, Alex B., Goldstein, Allen H., Keutsch, Frank N., Springston, Stephen R., Watson, Thomas B., Artaxo, Paulo, Souza, Rodrigo A. F., McKinney, Karena A., and Martin, Scot T.. Isoprene photo-oxidation products quantify the effect of pollution on hydroxyl radicals over Amazonia. United States: N. p., 2018. Web. doi:10.1126/sciadv.aar2547.
Liu, Yingjun, Seco, Roger, Kim, Saewung, Guenther, Alex B., Goldstein, Allen H., Keutsch, Frank N., Springston, Stephen R., Watson, Thomas B., Artaxo, Paulo, Souza, Rodrigo A. F., McKinney, Karena A., & Martin, Scot T.. Isoprene photo-oxidation products quantify the effect of pollution on hydroxyl radicals over Amazonia. United States. doi:10.1126/sciadv.aar2547.
Liu, Yingjun, Seco, Roger, Kim, Saewung, Guenther, Alex B., Goldstein, Allen H., Keutsch, Frank N., Springston, Stephen R., Watson, Thomas B., Artaxo, Paulo, Souza, Rodrigo A. F., McKinney, Karena A., and Martin, Scot T.. Wed . "Isoprene photo-oxidation products quantify the effect of pollution on hydroxyl radicals over Amazonia". United States. doi:10.1126/sciadv.aar2547. https://www.osti.gov/servlets/purl/1433944.
@article{osti_1433944,
title = {Isoprene photo-oxidation products quantify the effect of pollution on hydroxyl radicals over Amazonia},
author = {Liu, Yingjun and Seco, Roger and Kim, Saewung and Guenther, Alex B. and Goldstein, Allen H. and Keutsch, Frank N. and Springston, Stephen R. and Watson, Thomas B. and Artaxo, Paulo and Souza, Rodrigo A. F. and McKinney, Karena A. and Martin, Scot T.},
abstractNote = {Nitrogen oxides (NOx) emitted from human activities are believed to regulate the atmospheric oxidation capacity of the troposphere. However, observational evidence is limited for the low-to-median NOx concentrations prevalent outside of polluted regions. Directly measuring oxidation capacity, represented primarily by hydroxyl radicals (OH), is challenging, and the span in NOx concentrations at a single observation site is often not wide. Concentrations of isoprene and its photo-oxidation products were used to infer the equivalent noontime OH concentrations. The fetch at an observation site in central Amazonia experienced varied contributions from background regional air, urban pollution, and biomass burning. The afternoon concentrations of reactive nitrogen oxides (NOy), indicative of NOx exposure during the preceding few hours, spanned from 0.3 to 3.5 parts per billion. Accompanying the increase of NOy concentration, the inferred equivalent noontime OH concentrations increased by at least 250% from 0.6 × 106 to 1.6 × 106 cm-3. The conclusion is that, compared to background conditions of low NOx concentrations over the Amazon forest, pollution increased NOx concentrations and amplified OH concentrations, indicating the susceptibility of the atmospheric oxidation capacity over the forest to anthropogenic influence and reinforcing the important role of NOx in sustaining OH concentrations.},
doi = {10.1126/sciadv.aar2547},
journal = {Science Advances},
number = 4,
volume = 4,
place = {United States},
year = {Wed Apr 11 00:00:00 EDT 2018},
month = {Wed Apr 11 00:00:00 EDT 2018}
}

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