Urban influence on the concentration and composition of submicron particulate matter in central Amazonia

Author(s):Show less -

de Sa, Suzane S. ^[1] ; Palm, Brett B. ^{[2, 3]} ; Campuzano-Jost, Pedro ^{[2, 3]} ; Day, Douglas A. ^{[2, 3]} ; Hu, Weiwei ^[3] ; Isaacman-VanWertz, Gabriel ^{[4, 5]} ; Yee, Lindsay D. ^[4] ; Brito, Joel ^{[6, 7]} ; Carbone, Samara ^{[6, 8]} ; Ribeiro, Igor O. ^[9] ; Cirino, Glauber G. ^{[10, 11]} ; Liu, Yingjun ^{[4, 1]} ; Thalman, Ryan ^{[12, 13]} ; Sedlacek, Arthur ^[12] ; Funk, Aaron ^[14] ; Schumacher, Courtney ^[14] ; Shilling, John E. ^[15] ; Schneider, Johannes ^[16] ; Artaxo, Paulo ^[6] ; Goldstein, Allen H. ^[4] ; Souza, Rodrigo A. F. ^[9] ; Wang, Jian ^[12] ; McKinney, Karena A. ^{[1, 17]} ; Barbosa, Henrique ^[6] ; Alexander, M. Lizabeth ^[18] ; Jimenez, Jose L. ^{[2, 3]} ; Martin, Scot T. ^{[1, 19]}

Affiliation:Show less -

^[1] Harvard Univ, Sch Engn & Appl Sci, Cambridge, MA 02138 - USA

^[2] Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80309 - USA

^[3] Univ Colorado, Dept Chem, Boulder, CO 80309 - USA

^[4] Univ Calif Berkeley, Dept Environm Sci Policy & Management, Berkeley, CA 94720 - USA

^[5] Virginia Tech, Dept Civil & Environm Engn, Blacksburg, VA - USA

^[6] Univ Sao Paulo, Inst Phys, Sao Paulo - Brazil

^[7] Univ Blaise Pascal, Lab Meteorol Phys LaMP, Aubiere - France

^[8] Univ Fed Uberlandia, Inst Agr Sci, Uberlandia, MG - Brazil

^[9] Amazonas State Univ, Sch Technol, Manaus, Amazonas - Brazil

^[10] Natl Inst Amazonian Res, Manaus, Amazonas - Brazil

^[11] Fed Univ Para, Geosci Inst, Dept Meteorol, Belem, Para - Brazil

^[12] Brookhaven Natl Lab, Upton, NY 11973 - USA

^[13] Snow Coll, Dept Chem, Richfield, UT - USA

^[14] Texas A&M Univ, Dept Atmospher Sci, College Stn, TX - USA

^[15] Pacific Northwest Natl Lab, Atmospher Sci & Global Change Div, Richland, WA - USA

^[16] Max Planck Inst Chem, Particle Chem Dept, Mainz - Germany

^[17] Colby Coll, Dept Chem, Waterville, ME 04901 - USA

^[18] Pacific Northwest Natl Lab, Environm Mol Sci Lab, Richland, WA - USA

^[19] Harvard Univ, Dept Earth & Planetary Sci, 20 Oxford St, Cambridge, MA 02138 - USA

• Document type: Journal article
• Source: Atmospheric Chemistry and Physics; v. 18, n. 16, p. 12185-12206, AUG 23 2018.
• Web of Science Citations: 7

Abstract

An understanding of how anthropogenic emissions affect the concentrations and composition of airborne particulate matter (PM) is fundamental to quantifying the influence of human activities on climate and air quality. The central Amazon Basin, especially around the city of Manaus, Brazil, has experienced rapid changes in the past decades due to ongoing urbanization. Herein, changes in the concentration and composition of submicron PM due to pollution downwind of the Manaus metropolitan region are reported as part of the GoAmazon2014/5 experiment. A high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and a suite of other gas-and particle-phase instruments were deployed at the ``T3{''} research site, 70 km downwind of Manaus, during the wet season. At this site, organic components represented 79 +/- 7% of the non-refractory PM1 mass concentration on average, which was in the same range as several upwind sites. However, the organic PM1 was considerably more oxidized at T3 compared to upwind measurements. Positive-matrix factorization (PMF) was applied to the time series of organic mass spectra collected at the T3 site, yielding three factors representing secondary processes (73 +/- 15% of total organic mass concentration) and three factors representing primary anthropogenic emissions (27 +/- 15 %). Fuzzy c-means clustering (FCM) was applied to the afternoon time series of concentrations of NOy, ozone, total particle number, black carbon, and sulfate. Four clusters were identified and characterized by distinct air mass origins and particle compositions. Two clusters, Bkgd-1 and Bkgd2, were associated with background conditions. Bkgd-1 appeared to represent near-field atmospheric PM production and oxidation of a day or less. Bkgd-2 appeared to represent material transported and oxidized for two or more days, often with out-of-basin contributions. Two other clusters, Pol-1 and Pol-2, represented the Manaus influence, one apparently associated with the northern region of Manaus and the other with the southern region of the city. A composite of the PMF and FCM analyses provided insights into the anthropogenic effects on PM concentration and composition. The increase in mass concentration of submicron PM ranged from 25% to 200% under polluted compared with background conditions, including contributions from both primary and secondary PM. Furthermore, a comparison of PMF factor loadings for different clusters suggested a shift in the pathways of PM production under polluted conditions. Nitrogen oxides may have played a critical role in these shifts. Increased concentrations of nitrogen oxides can shift pathways of PM production from HO2-dominant to NO-dominant as well as increase the concentrations of oxidants in the atmosphere. Consequently, the oxidation of biogenic and anthropogenic precursor gases as well as the oxidative processing of preexisting atmospheric PM can be accelerated. This combined set of results demonstrates the susceptibility of atmospheric chemistry, air quality, and associated climate forcing to anthropogenic perturbations over tropical forests. (AU)

• FAPESP's process: 13/05014-0 - GoAmazon: interactions of the urban plume of Manaus with biogenic forest emissions in Amazonia
• Grantee: Paulo Eduardo Artaxo Netto
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants