Investigations of the Chemistry of Secondary Aerosol Formation Using Thermal Desorption Particle Beam Mass Spectrometry

EPA Grant Number: R826235
Title: Investigations of the Chemistry of Secondary Aerosol Formation Using Thermal Desorption Particle Beam Mass Spectrometry
Investigators: Ziemann, Paul J.
Institution: University of California - Riverside
EPA Project Officer: Shapiro, Paul
Project Period: December 1, 1997 through November 30, 2000 (Extended to November 30, 2001)
Project Amount: $294,762
RFA: Ambient Air Quality (1997) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Air


Understanding the effects of fine atmospheric aerosol particles on human health and the environment, and developing strategies for controlling fine particle concentrations, will require much more information on aerosol chemistry than is currently available. In this project a newly developed thermal desorption particle beam mass spectrometer (TDPBMS) that is capable of real-time, quantitative chemical analysis of particles as small as 0.01 µm in diameter will be used in conjunction with other tools for environmental chamber studies of the chemistry of secondary aerosol formation. The objectives of the project are to: (1) investigate the products, kinetics, and mechanisms of secondary aerosol formation resulting from the photochemical reactions of selected VOC of anthropogenic and biogenic origin with OH, NO3, and O3 (2) investigate the effects of SO2, NH3, H2O and seed particles on the chemistry of secondary aerosol formation in these VOC/oxidant systems, and (3) compile a thermal desorption particle beam mass spectral library of compounds found in secondary aerosol.


Environmental chamber studies will be carried out by adding controlled amounts of VOC, oxidants, and other gases to an 7000 liter chamber and then monitoring gas concentrations and particle properties in real-time. Particle composition will be measured in real-time using TDPBMS, the particle size distribution will be monitored using a scanning electrical mobility spectrometer, the hygroscopic properties of the particles will be investigated using a tandem differential mobility analyzer, and size-segregated particle samples will be collected with a filter or microorifice uniform deposit impactor for off-line analysis by gas chromatography-mass spectrometry.

Expected Results:

The results of this research will help to elucidate the fundamental chemical and physical processes involved in secondary aerosol formation in the atmosphere. This includes the kinetics, products, and mechanisms of gas-phase reactions by which key atmospheric oxidants convert the major classes of atmospheric VOC to condensable species, and also the heterogeneous (surface or liquid phase) reactions, condensation, and homogeneous nucleation processes involved in gas-to-particle conversion. Knowledge gained concerning the formation of particulate organics, sulfates, and nitrates can be used for the development of more sophisticated models of secondary aerosol formation and behavior. Such models can be included as modules in airshed models, which can in turn be used to estimate the effects of human activities (including pollution control strategies) on air quality. Information on the chemical composition of the aerosol will also be valuable for understanding the effects of fine particles on human health by identifying chemical compounds that should be screened for potential toxicity.

Publications and Presentations:

Publications have been submitted on this project: View all 22 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 8 journal articles for this project

Supplemental Keywords:

absorption, adsorption, environmental chemistry, gas-particle partitioning, measurement methods, particulates, tropospheric., RFA, Scientific Discipline, Air, Toxics, particulate matter, Chemical Engineering, air toxics, Environmental Chemistry, VOCs, Chemistry, tropospheric ozone, Atmospheric Sciences, Chemistry and Materials Science, Environmental Engineering, ambient air quality, ambient aerosol, particulates, secondary aerosol formation, air pollutants, volatile air toxics, environmental chamber studies, mass spectrometry, air quality models, ambient measurement methods, particle beam mass spectrometry, spectroscopic studies, chemical composition, oxidant gas, aerosol, oxidant precursors, Volatile Organic Compounds (VOCs), atmospheric chemistry, aerosol production

Relevant Websites: Exit

Progress and Final Reports:

  • 1998
  • 1999
  • 2000 Progress Report
  • Final