Microscopic Characterization of Carbonaceous Aerosol Particle Aging in the Outflow from Mexico City

Journal Article · Mon Feb 01 04:00:00 EST 2010 · Atmospheric Chemistry and Physics, 10(3):961-976

DOI:https://doi.org/10.5194/acp-10-961-2010· OSTI ID:974928

Moffet, Ryan C; Henn, Tobias R; Tivanski, Alexei V; Hopkins, Rebecca J; Desyaterik, Yury; Kilcoyne, Arthur L; Tyliszczak, T; Fast, Jerome D; Barnard, James C; Shutthanandan, V; Cliff, Steven S; Perry, K D; Laskin, Alexander; Gilles, Marry K

The physical and chemical transformations of particles aged in the outflow from Mexico City were investigated for the transport event of 22 March 2006. This study was part of the Megacities Initiative: Local and Global Research Observations (MILAGRO) 2006 field campaign. A detailed chemical analysis of individual particles was performed using a combination of complementary spectro-microscopic techniques. These techniques included scanning transmission X-ray microscopy (STXM) coupled with near edge X-ray absorption fine structure spectroscopy (NEXAFS) and computer controlled scanning electron microscopy with an energy dispersive X-ray analyzer (CCSEM/EDX). As the aerosol plume evolves from the city center, the organic mass per particle increases and the fraction of carbon-carbon double bonds (associated with elemental carbon) decreases. Organic functional groups enhanced with age include: carboxylic acids, alkyl groups, and oxygen bonded alkyl groups. At the city center (T0) the most prevalent aerosol type contained inorganic species (composed of sulfur, nitrogen, oxygen, and potassium) coated with organic material. At the T1 and T2 sites, located northeast of T0 (~29 km and ~65 km, respectively), the fraction of homogenously mixed organic particles increased in both size and number. These observations illustrate the evolution of the physical mixing state and organic bonding in individual particles in a photochemically active environment.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 974928
• Report Number(s): PNNL-SA-67629; 19792; KP1205030
• Journal Information: Atmospheric Chemistry and Physics, 10(3):961-976, Journal Name: Atmospheric Chemistry and Physics, 10(3):961-976 Journal Issue: 3 Vol. 10
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ABSORPTION
AEROSOLS
AGING
BONDING
CARBON
CARBOXYLIC ACIDS
CHEMICAL ANALYSIS
COMPUTERS
DOUBLE BONDS
Environmental Molecular Sciences Laboratory
FINE STRUCTURE
FUNCTIONALS
MICROSCOPY
NITROGEN
OXYGEN
PLUMES
POTASSIUM
SCANNING ELECTRON MICROSCOPY
SPECTROSCOPY
SULFUR
TRANSFORMATIONS