skip to main content

DOE PAGESDOE PAGES

Title: Anthropogenic influences on the physical state of submicron particulate matter over a tropical forest

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 carbonmore » 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.« less
Authors:
 [1] ;  [1] ; ORCiD logo [2] ;  [1] ;  [3] ;  [4] ;  [5] ;  [1] ;  [2] ; ORCiD logo [6] ;  [5] ; ORCiD logo [7] ;  [4] ;  [8] ;  [5] ; ORCiD logo [9] ; ORCiD logo [10] ;  [11] ;  [2] ; ORCiD logo [6] more »; ORCiD logo [5] ;  [7] ;  [4] ;  [12] ; ORCiD logo [4] ; ORCiD logo [5] ;  [1] « less
  1. Harvard Univ., Cambridge, MA (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Xiamen Univ. (China)
  4. Brookhaven National Lab. (BNL), Upton, NY (United States)
  5. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  6. Univ. of Colorado, Boulder, CO (United States). Cooperative Inst. for Research in Environmental Sciences (CIRES)
  7. National Inst. of Amazonian Research, Manaus (Brazil)
  8. Meteorological Research Inst. (MRI), Tsukuba (Japan)
  9. Univ. of Sao Paulo (Brazil)
  10. Univ. of British Columbia, Vancouver, BC (Canada)
  11. Arizona State Univ., Tempe, AZ (United States)
  12. Amazonas State Univ., Manaus (Brazil)
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Atmospheric Chemistry and Physics (Online)
Additional Journal Information:
Journal Name: Atmospheric Chemistry and Physics (Online); Journal Volume: 17; Journal Issue: 3; Journal ID: ISSN 1680-7324
Publisher:
European Geosciences Union
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES
OSTI Identifier:
1379723