Grantee Research Project Results

Experimental Investigation of the Evolution of the Size and Composition Distribution of Atmospheric Organic Aerosols

EPA Grant Number: R824970C010
Subproject: this is subproject number 010 , established and managed by the Center Director under grant R824970
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: HSRC (1989) - Northeast HSRC
Center Director: Sidhu, Sukh S.
Title: Experimental Investigation of the Evolution of the Size and Composition Distribution of Atmospheric Organic Aerosols
Investigators: Cass, Glen
Institution: Massachusetts Institute of Technology , California Institute of Technology
Current Institution: California Institute of Technology
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 1992 through May 31, 1998
Project Amount: Refer to main center abstract for funding details.
RFA: Center on Airborne Organics (1993) Recipients Lists
Research Category: Targeted Research

Objective:

The purpose of this research project is to conduct a field experimental program in which the evolution of the size distribution and chemical composition of the urban aerosol complex is observed using methods that focus on the evolution of the individual aerosol particles. The goal is to determine how primary particles emitted from the many air pollution sources in the city are modified by gas-to-particle conversion processes in the atmosphere.

Approach:

Experiments will be conducted in which the background marine aerosol first is characterized based on measurements made at Santa Catalina Island which is located upwind of the Los Angeles area in the summer. Then Lagrangian air parcels will be sampled as they are transported across the urban Los Angeles area to Riverside, CA, in the presence of direct emissions from urban pollution sources and as the aerosol is modified by gas-to-particle conversion processes. Both organic and inorganic aerosol species will be sampled simultaneously, (1) by time-of-flight mass spectrometers that view single particle size and composition, (2) by cascade impactors from which particle chemical composition can be measured as a function of particle size, (3) by filter-based samplers and (4) by electronic instruments that measure particle size distributions directly and continuously.

Rationale:

Completion of the research proposed here on the evolution of the Southern California aerosol as it is transported across the Los Angeles urban area will meet several needs. First these experiments will serve to determine how the single particle data base generated by time-offlight mass spectrometers can be aggregated to recreate the bulk aerosol size distribution and chemical composition as measured by cascade impactors and electronic size distribution analyzers. Second, the results will describe the evolution of the Southern California aerosol as it is transported and transformed in the atmosphere. Since Rubidoux near the proposed trajectory end points at Riverside probably has the highest fine particle concentrations in the nation, detailed information on how that aerosol is created is expected to advance our understanding of how such severe air quality problems can be controlled. Third, the experiments will provide a model verification data set for testing the predictions of Lagrangian particle aerosol processes air quality models that are needed for use as design tools during the control strategy testing phase of the state implementation planningprocess for airborne particulate matter. Through comparison of ambient particle composition to the composition of particles emitted from major emission source types (which is being measured in a separate study), it is hoped that new tools and insights will be developed that can clearly identify those particles in the atmosphere that evolve from the emissions from specific source types.

Supplemental Keywords:

organic, aerosol, atmosphere, air., RFA, Scientific Discipline, Air, Geographic Area, Waste, Ecosystem Protection/Environmental Exposure & Risk, particulate matter, Environmental Chemistry, State, Monitoring/Modeling, Fate & Transport, Environmental Monitoring, Atmospheric Sciences, ambient aerosol, particulates, urban air, fate and transport, chemical characteristics, aerosol time-of-flight mass spectrometry (ATOFMS), atmospheric organic aerosols, atmospheric transformation, emissions, gas to particle conversion, chemical kinetics, organics, size distribution, California (CA), urban environment, urban air , aerosols, particle transport, atmospheric chemistry, organic contaminants, real-time monitoring

Main Center Abstract and Reports:

R824970    HSRC (1989) - Northeast HSRC

Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R824970C001 Chemical Kinetic Modeling of Formation of Products of Incomplete Combustion from Spark-ignition Engines
R824970C002 Combustion Chamber Deposit Effects on Engine Hydrocarbon Emissions
R824970C003 Atmospheric Transformation of Volatile Organic Compounds: Gas-Phase Photooxidation and Gas-to-Particle Conversion
R824970C004 Mathematical Models of the Transport and Fate of Airborne Organics
R824970C005 Elementary Reaction Mechanism and Pathways for Atmospheric Reactions of Aromatics - Benzene and Toluene
R824970C006 Simultaneous Removal of Soot and NOx from the Exhaust of Diesel Powered Vehicles
R824970C007 Modeling Gas-Phase Chemistry and Heterogeneous Reaction of Polycyclic Aromatic Compounds
R824970C008 Fundamental Study on High Temperature Chemistry of Oxygenated Hydrocarbons as Alternate Motor Fuels and Additives
R824970C009 Markers for Emissions from Combustion Sources
R824970C010 Experimental Investigation of the Evolution of the Size and Composition Distribution of Atmospheric Organic Aerosols
R824970C011 Microengineered Mass Spectrometer for in-situ Measurement of Airborne Contaminants