Single particle mass spectrometry combustion source characterization and atmospheric apportionment of vehicular, coal and biofuel exhaust emissions

Emissions from combustion sources are known to cause adverse environmental effects that include adverse health effects as well as atmospheric visibility degradation. Reasons such as these are the motivation to characterize major combustion aerosol sources with aerosol time-of-flight mass spectrometry (ATOFMS). This is an on-line single particle mass spectrometer that simultaneously determines the size and chemical composition of individual aerosol particles. Because ATOFMS is a relatively new form of instrumentation for source characterization and atmospheric monitoring purposes certain fundamental studies are performed and discussed. A study that illustrates the instruments reproducibility during transient source characterization experiments as well as a laboratory study for the positive identification of elemental carbon species from ATOFMS mass spectra are discussed. Next, source characterization results are described from vehicular, biofuel burning and coal combustion particle emissions. These results illustrate that combustion sources emit numerous single particle types with specific single particle chemical associations. Also, specific chemical markers that may be used for the ambient identification of particles emitted from these combustion sources are discussed. The source characterization results are also directly compared to one another to illustrate distinct chemical differences between the bulk emitted aerosol as well as the major particle types emitted from these sources. Finally, a new method for single particle source apportionment using ATOFMS is reported. This source apportionment method utilizes a neural network computer algorithm, adaptive resonance theory (ART-2a). The application of the combustion source characterization results are applied to ambient data collected throughout the United States in Bakersfield, CA, Laporte, TX, and Atlanta, GA, as well as from the 1999 Indian Ocean Experiment using ART-2a for single particle source identification and apportionment.