Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 1759-1773, 2017
http://www.atmos-chem-phys.net/17/1759/2017/
doi:10.5194/acp-17-1759-2017
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
06 Feb 2017
Anthropogenic influences on the physical state of submicron particulate matter over a tropical forest
Adam P. Bateman1, Zhaoheng Gong1, Tristan H. Harder2,a, Suzane S. de Sá1, Bingbing Wang3,4, Paulo Castillo5, Swarup China3, Yingjun Liu1, Rachel E. O'Brien2,b, Brett B. Palm6, Hung-Wei Shiu3,c, Glauber G. Cirino7, Ryan Thalman5,d, Kouji Adachi8, M. Lizabeth Alexander3, Paulo Artaxo9, Allan K. Bertram10, Peter R. Buseck11, Mary K. Gilles2, Jose L. Jimenez6, Alexander Laskin3, Antonio O. Manzi7, Arthur Sedlacek5, Rodrigo A. F. Souza12, Jian Wang5, Rahul Zaveri3, and Scot T. Martin1,13 1School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
2Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
3William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, USA
4State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
5Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, NY, USA
6Department of Chemistry and Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO, USA
7National Institute of Amazonian Research, Manaus, Amazonas, Brazil
8Atmospheric Environment and Applied Meteorology Research Department, Meteorological Research Institute, Tsukuba, Ibaraki, Japan
9Departamento de Física Aplicada, University of São Paulo, São Paulo, Brazil
10Department of Chemistry, University of British Columbia, Vancouver, BC, Canada
11School of Earth and Space Exploration & School of Molecular Sciences, Arizona State University, Tempe, AZ, USA
12Amazonas State University, Manaus, Amazonas, Brazil
13Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
anow at: Physikalisches Institut, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
bnow at: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
cnow at: Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu, Taiwan 30076
dnow at: Departments of Chemistry and Natural Resources, Snow College, Richfield, UT, USA
Abstract. The occurrence of nonliquid and liquid physical states of submicron atmospheric particulate matter (PM) downwind of an urban region in central Amazonia was investigated. Measurements were conducted during two intensive operating periods (IOP1 and IOP2) that took place during the wet and dry seasons of the GoAmazon2014/5 campaign. Air masses representing variable influences of background conditions, urban pollution, and regional- and continental-scale biomass burning passed over the research site. As the air masses varied, particle rebound fraction, an indicator of physical state, was measured in real time at ground level using an impactor apparatus. Micrographs collected by transmission electron microscopy confirmed that liquid particles adhered, while nonliquid particles rebounded. Relative humidity (RH) was scanned to collect rebound curves. When the apparatus RH matched ambient RH, 95 % of the particles adhered as a campaign average. Secondary organic material, produced for the most part by the oxidation of volatile organic compounds emitted from the forest, produces liquid PM over this tropical forest. During periods of anthropogenic influence, by comparison, the rebound fraction dropped to as low as 60 % at 95 % RH. Analyses of the mass spectra of the atmospheric PM by positive-matrix factorization (PMF) and of concentrations of carbon monoxide, total particle number, and oxides of nitrogen were used to identify time periods affected by anthropogenic influences, including both urban pollution and biomass burning. The occurrence of nonliquid PM at high RH correlated with these indicators of anthropogenic influence. A linear model having as output the rebound fraction and as input the PMF factor loadings explained up to 70 % of the variance in the observed rebound fractions. Anthropogenic influences can contribute to the presence of nonliquid PM in the atmospheric particle population through the combined effects of molecular species that increase viscosity when internally mixed with background PM and increased concentrations of nonliquid anthropogenic particles in external mixtures of anthropogenic and biogenic PM.

Citation: Bateman, A. P., Gong, Z., Harder, T. H., de Sá, S. S., Wang, B., Castillo, P., China, S., Liu, Y., O'Brien, R. E., Palm, B. B., Shiu, H.-W., Cirino, G. G., Thalman, R., Adachi, K., Alexander, M. L., Artaxo, P., Bertram, A. K., Buseck, P. R., Gilles, M. K., Jimenez, J. L., Laskin, A., Manzi, A. O., Sedlacek, A., Souza, R. A. F., Wang, J., Zaveri, R., and Martin, S. T.: Anthropogenic influences on the physical state of submicron particulate matter over a tropical forest, Atmos. Chem. Phys., 17, 1759-1773, doi:10.5194/acp-17-1759-2017, 2017.
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Short summary
The occurrence of nonliquid and liquid physical states of submicron atmospheric particulate matter (PM) downwind of an urban region in central Amazonia was investigated. Air masses representing background conditions, urban pollution, and regional- and continental-scale biomass were measured. Anthropogenic influences contributed to the presence of nonliquid PM in the atmospheric particle population, while liquid PM dominated during periods of biogenic influence.
The occurrence of nonliquid and liquid physical states of submicron atmospheric particulate...
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