2006 Progress Report: Near Real-Time Speciation of Organic Aerosols for Source ApportionmentEPA Grant Number: R832166
Title: Near Real-Time Speciation of Organic Aerosols for Source Apportionment
Investigators: Johnston, Murray V.
Institution: University of Delaware
EPA Project Officer: Chung, Serena
Project Period: January 1, 2005 through December 31, 2007 (Extended to December 31, 2008)
Project Period Covered by this Report: January 1, 2006 through December 31, 2007
Project Amount: $450,000
RFA: Source Apportionment of Particulate Matter (2004) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Particulate Matter , Air
This project includes five specific objectives: (1) Develop a photoionization aerosol mass spectrometer (PIAMS) for near real-time measurement of trace organic constituents in fine particles. (2) Couple PIAMS with an aerosol concentrator to reduce the sampling time of PIAMS to 2 minutes or less for ambient urban air. (3) Acquire improved PIAMS signatures (source profiles) for those sources where elemental data may be ambiguous or non existent—for example secondary organic aerosols (SOA), highway traffic, and meat cooking operations. (4) Use the concentrator and PIAMS to measure trace organic constituents in fine particles in Wilmington, Delaware, at the State of Delaware Department of Natural Resources and Environmental Control Air Quality Measurement Site; concurrent carbonaceous particulate matter measurements will include semi continuous organic carbon/elemental carbon (OC/EC), gas chromatography/mass spectrometry (GC/MS) of collected Hi-Vol aerosol samples, OC/EC on Federal Reference Method (FRM) Samplers for fine particulate matter (PM2.5), and particulate mass. (5) Develop and refine source apportionment models using the organics data.
During the second year of this project, Objectives 1 and 2 were completed; Objectives 3 and 4 were addressed.
Objective 1: The PIAMS was reconfigured for field work, including: (1) hardware and software development for automated sample collection and data acquisition; (2) an improved collection probe design which maintained robust alignment with the particle beam and permitted the probe surface to be cooled to inhibit evaporation of semivolatile compounds; (3) redesign of vacuum components for robust use in the field; and (4) design and installation of a virtual impactor to more closely match the inlet flow of PIAMS to the outlet flow of the concentrator (see Objective 2).
Objective 2: A mini-versatile aerosol concentration system (m-VACES) was obtained from the University of Southern California and connected to the PIAMS for measurements of ambient aerosol. With the combination of PIAMS and m-VACES, intense signals were obtained for a 2-minute sampling time of ambient aerosol. The total “cycle” time of the instrument for analysis of successive samples was 3.5 minutes.
Objective 3: We have continued to study biogenic source signatures by using PIAMS to characterize products of the reaction of monoterpenes with ozone. In addition, a 500 L tedlar bag assembly and sampling pump was built to collect aerosol at a remote site and transport it back to the PIAMS instrument for subsequent analysis.
Objective 4: An initial measurement campaign was performed at the State of Delaware Air Quality Monitoring Site in Wilmington, Delaware. PIAMS was operated for a 2-week interval in June 2006. Different organic compounds showed different time responses of their PIAMS signals. Some compounds did not vary significantly with time. Others showed a strong diurnal variation. Still others exhibited short term “spikes” in signal intensity. These data continue to be processed and analyzed.
In the coming year, Objectives 3–5 will be addressed. Source signatures for Objective 3 will be obtained with the sampling bag assembly described above. Objective 4 will continue with a second ambient measurement campaign in the spring/summer of 2007 at the State of Delaware Air Quality Measurement Site in Wilmington, Delaware. Objective 5 will be pursued with the ambient dataset obtained from Objective 4.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
|Other project views:||All 9 publications||5 publications in selected types||All 5 journal articles|
||Tolocka MP, Heaton KJ, Dreyfus MA, Wang S, Zordan CA, Saul TD, Johnston MV. Chemistry of particle inception and growth during [alpha]-pinene ozonolysis. Environmental Science & Technology 2006;40(6):1843-1848.||