Collaborative Research: TEM studies of soot organic matter and associated aerosol particals during CalNex

Project: Research project

Description

New information about the role of aerosol particles in climate change and health will be provided by a three-pronged research program to a) obtain detailed information about aerosol particles, including metalbearing nanoparticles, collected in the greater Los Angeles area during the CalNex campaign; b) develop and apply new ways of characterizing organic matter (OM) within aerosol particles; and c) integrate those results into a global climate model. In part a) transmission electron microscope (TEM) measurements of the various types of aerosol particles during CalNex will provide data regarding 2D and 3D shapes, structures, optical properties, intergrowths, and mixing states that are unavailable by other methods and will complement the information collected by other groups. As one of only a few groups specializing in transmission electron microscopy, we will provide uniquely detailed knowledge about CalNex aerosol particles. The TEM results of part a) will be compared to those obtained by complementary measurements made using ToF-AMS (Jose Jimenez), SP2 and SP-AMS (Hugh Coe), and other techniques. They will be compared to those of our prior study in and around Mexico City, thereby contributing to a synthesized overview of aerosol properties in megacities. Part b) will include determinations of i) OM functional groups and refractive indices using ultrahigh-resolution (0.1 eV) electron energy-loss spectroscopy with new aberration-corrected TEMs, ii) OM hygroscopicity using a unique environmental cell within a TEM, and iii) OM volatility using controlled step heating in the environmental cell. By comparing results from these emerging analytical techniques, we anticipate obtaining new microphysical and chemical information about the semi-volatile and non-volatile fractions of airborne OM within individual particles. In part c), we will use the results of parts a) and b) to calculate optical properties of internally mixed soot and OM, which will then be incorporated into global climate models to evaluate their broad impact.

Description

SUMMARY OF PROPOSED WORK We propose to extend the CalNex project to a comparison of aerosol particles collected in and near Manaus, Brazil, a large city surrounded by rural areas. A major goal of our CalNex project was to develop and use TEM measurements and analyses of individual aerosol particles to understand how they change with time in the atmosphere and how these changes affect properties such as hygroscopicity, light absorption, and, ultimately, climate. With this proposal we are requesting a funding supplement and time extension to provide greater generality to our CalNex results through collection of additional samples for analysis and comparison from another area where emissions from an urban region impinge on a natural environment. We will be looking at aerosol particles, many of which are similar to those examined during CalNex, and and to examine how atmospheric reactions and aging affect both their optical and microphysical properties. This study will be a logical extension of our CalNex effort that takes advantage of the convenient availability of samples and data sets from many instruments, comparable to those from CalNex but from a significantly different setting.
StatusFinished
Effective start/end date7/15/1012/31/14

Funding

  • National Science Foundation (NSF): $566,548.00

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soot
aerosol
organic matter
electron
hygroscopicity
accelerator mass spectrometry
optical property
global climate
transmission electron microscopy
climate modeling
aerosol property
megacity
urban region
refractive index
research program
functional group
rural area
analytical method
spectroscopy
heating