Skip to content

Processing of soot in an urban environment: case study from the Mexico City Metropolitan Area

by K.S. Johnson, B Zuberi, LT Molina, M.J. Molina, M.J. Iedema, J.P. Cowin, D.J. Gaspar, C Wang, A Laskin show all authors
Atmospheric Chemistry and Physics Discussions ()
Get full text at journal

Abstract

Chemical composition, size, and mixing state of atmospheric particles are critical in determining their effects on the environment. There is growing evidence that soot aerosols play a particularly important role in both climate and human health, but still relatively little is known of their physical and chemical nature. In addition, the atmospheric residence times and removal mechanisms for soot are neither well understood nor adequately represented in regional and global climate models. To investigate the effect of locality and residence time on properties of soot and mixing state in a polluted urban environment, particles of diameter 0.2–2.0μm were collected in the Mexico City MetropolitanArea (MCMA) during the MCMA-2003 Field Campaignfrom various sites within the city. Individual particle analysisby different electron microscopy methods coupled withenergy dispersed x-ray spectroscopy, and secondary ionizationmass spectrometry show that freshly-emitted soot particlesbecome rapidly processed in the MCMA. Whereas freshparticulate emissions from mixed-traffic are almost entirelycarbonaceous, consisting of soot aggregates with liquid coatingssuggestive of unburned lubricating oil and water, ambientsoot particles which have been processed for less than afew hours are heavily internally mixed, primarily with ammoniumsulfate. Single particle analysis suggests that thismixing occurs through several mechanisms that require furtherinvestigation. In light of previously published results,the internally-mixed nature of processed soot particles is expectedto affect heterogeneous chemistry on the soot surface,including interaction with water during wet-removal.

Cite this document (BETA)

Readership Statistics

4 Readers on Mendeley
by Discipline
 
25% Computer Science
 
25% Economics, Econometrics and Finance
 
25% Social Sciences
by Academic Status
 
50% Researcher
 
25% Student > Master
 
25% Student > Ph. D. Student
by Country
 
50% United States
 
25% South Africa
 
25% Ireland

Tags

Sign up today - FREE

Mendeley saves you time finding and organizing research. Learn more

  • All your research in one place
  • Add and import papers easily
  • Access it anywhere, anytime

Start using Mendeley in seconds!

Sign up & Download

Already have an account? Sign in