Grantee Research Project Results
1999 Progress Report: Real-Time Monitoring of Individual Atmospheric Aerosol Particles: Establishing Correlations Between Particle Size and Chemical Speciation
EPA Grant Number: R826240Title: Real-Time Monitoring of Individual Atmospheric Aerosol Particles: Establishing Correlations Between Particle Size and Chemical Speciation
Investigators: Prather, Kimberly A.
Institution: University of California - Riverside
EPA Project Officer: Hahn, Intaek
Project Period: February 1, 1998 through January 31, 2001
Project Period Covered by this Report: February 1, 1999 through January 31, 2000
Project Amount: $547,000
RFA: Ambient Air Quality (1997) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Air
Objective:
The objectives of this research project involve using a newly developed aerosol analysis technique developed in our laboratory, aerosol time-of-flight mass spectrometry (ATOFMS), for taking real-time measurements of the individual particle size and composition of ambient aerosols in a variety of locations in the United States. ATOFMS couples time-of-flight aerodynamic sizing with laser desorption ionization (LDI) time-of-flight mass spectrometry, simultaneously measuring the size and chemical composition (as anions and cations) of individual aerosol particles in real time. One objective of this project involves establishing size-resolved composition variations at different locations. Single-particle signatures will be used to explore particle changes due to aging/chemistry, as well as to obtain information on particle sources in different regions of the United States. These studies will represent the first long-term studies conducted with the ATOFMS so efforts will be made to convert the qualitative data into more semiquantitative information on atmospheric particles that can be compared with other gas phase, particle phase, and meteorological data to further our understanding of aerosol chemistry on shorter timescales.
Prior to the start of this year, the overall objectives of this research project were changed when the U.S. Environmental Protection Agency (EPA) Particulate Matter (PM) Supersites Program was announced. Originally, ATOFMS was going to be used for PM sampling in southern California, but when the EPA Supersites Program began, this was viewed as a unique opportunity to perform research on PM in various air masses with unique chemistry across the United States, with the added benefit of having other state-of-the-art PM and gas-phase measurements simultaneously being taken. In the Atlanta Supersite study performed during this year of the contract, the ATOFMS was used characterize the chemical signatures of particles in the southeastern United States. One major objective of this study is to allow comparisons between the ATOFMS and other semicontinuous analysis methods.
Progress Summary:
The ATOFMS continuously sampled in Atlanta, GA, during August 3, 1999-September 1, 1999 as part of the Atlanta Supersite Study. During the study, ATOFMS was used to continuously measure the aerodynamic size and chemical composition of 455,444 particles that were acquired during the Atlanta Supersite Experiment in the fine fraction (0.2-2.5 µm). The inorganic and organic components of the particles were analyzed using laser desorption ionization time-of-flight mass spectrometry, generating either positive and/or negative ion mass spectra. The ATOFMS detected a complex mixture of particle types, including sodium, carbon (EC, OC, EC/OC), dust (Ca, Fe, Al), sulfate, nitrate, and ammonium. The ion signals, size distributions, and temporal evolutions of the different particle types were obtained. The complexity of the Atlanta aerosol on an individual particle basis demonstrates how single-particle data obtained with ATOFMS can be used to gain unique insights into the mixing state of urban aerosols. One key objective of this study is to develop scaling procedures for converting unscaled ATOFMS data into atmospherically relevant number concentrations that allow for comparison with other instruments.
Future Activities:
Further analysis of the ATOFMS data collected in the Grand Canyon Visibility and Scripps Institution of Oceanography Pier studies have been further analyzed. The ATOFMS Atlanta dataset has been entered into a database (Yet Another ATOFMS Data Analyzer, or YAADA) that allows rapid searching for specific ion markers, neural network analysis of the major particle types, and comparison with other instruments. In future work, we will begin comprehensive analysis by working on scaling the ATOFMS data using peripheral data to make comparisons with results from other semicontinuous techniques.
Journal Articles:
No journal articles submitted with this report: View all 23 publications for this projectSupplemental Keywords:
air, aerosol, particulate matter, PM, measurement methods, southeast, sulfates, organics, mobile sources, tropospheric, marine, chemical transport, visibility, ambient air, atmosphere, environmental chemistry, analytical, pollution, source allocation, real time, chemical analysis., RFA, Scientific Discipline, Air, particulate matter, Environmental Chemistry, tropospheric ozone, Ecology and Ecosystems, Environmental Monitoring, air sampling, ambient aerosol, chemical characteristics, particle size, aerosol time-of-flight mass spectrometry (ATOFMS), real time monitoring, atmospheric transport, chemical composition, chemical speciation sampling, particle transport, air pollution, ambient pollution control, fine particle formation, ambient measurement methods, aerosol samplingRelevant Websites:
http://atofms.ucsd.edu Exit
http://www.yaada.org Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.