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Title: Chemical imaging of ambient aerosol particles: Observational constraints on mixing state parameterization

In this study, a new parameterization for quantifying the mixing state of aerosol populations has been applied for the first time to samples of ambient particles analyzed using spectro-microscopy techniques. Scanning transmission X-ray microscopy/near edge X-ray absorption fine structure (STXM/NEXAFS) and computer-controlled scanning electron microscopy/energy dispersive X-ray spectroscopy (CCSEM/EDX) were used to probe the composition of the organic and inorganic fraction of individual particles collected on 27 and 28 June during the 2010 Carbonaceous Aerosols and Radiative Effects study in the Central Valley, California. The first field site, T0, was located in downtown Sacramento, while T1 was located near the Sierra Nevada Mountains. Mass estimates of the aerosol particle components were used to calculate mixing state metrics, such as the particle-specific diversity, bulk population diversity, and mixing state index, for each sample. The STXM data showed evidence of changes in the mixing state associated with a buildup of organic matter confirmed by collocated measurements, and the largest impact on the mixing state was due to an increase in soot dominant particles during this buildup. The mixing state from STXM was similar between T0 and T1, indicating that the increased organic fraction at T1 had a small effect on the mixingmore » state of the population. The CCSEM/EDX analysis showed the presence of two types of particle populations: the first was dominated by aged sea-salt particles and had a higher mixing state index (indicating a more homogeneous population); the second was dominated by carbonaceous particles and had a lower mixing state index.« less
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  1. Univ. of the Pacific, Stockton, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  3. Univ. of Illinois at Urbana-Champaign, Urbana, IL (United States)
  4. Univ. of California, Davis, CA (United States)
  5. Stony Brook Univ., Stony Brook, NY (United States); Univ. Claude Bernard Lyon 1, Villeurbanne (France)
  6. Stony Brook Univ., Stony Brook, NY (United States)
  7. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  8. Univ. of the Pacific, Stockton, CA (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research: Atmospheres
Additional Journal Information:
Journal Volume: 120; Journal Issue: 18; Journal ID: ISSN 2169-897X
American Geophysical Union
Research Org:
Stony Brook Univ., Stony Brook, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
OSTI Identifier: