Atmospheric Processing of Organic Particulate Matter: Formation, Properties, Long Range Transport, and RemovalEPA Grant Number: R831081
Title: Atmospheric Processing of Organic Particulate Matter: Formation, Properties, Long Range Transport, and Removal
Investigators: Donahue, Neil , Adams, Peter , Davidson, Cliff I. , Pandis, Spyros N. , Robinson, Allen
Institution: Carnegie Mellon University
EPA Project Officer: Chung, Serena
Project Period: September 1, 2003 through August 31, 2006
Project Amount: $449,994
RFA: Measurement, Modeling, and Analysis Methods for Airborne Carbonaceous Fine Particulate Matter (PM2.5) (2003) RFA Text | Recipients Lists
Research Category: Air , Air Quality and Air Toxics , Particulate Matter
Despite significant progress during the last two decades, organic PM remains the least understood component of atmospheric aerosol. We propose a comprehensive study of the chemical and physical processes resulting in the formation of secondary organic aerosol (SOA) and the chemical processing of primary organic PM. The project will combine laboratory work in the CMU indoor smog chamber facility with development and application of chemical transport models (CTMs). The results will be evaluated against the measurements of the EPA PM Supersites program.
(1) measurement of the SOA yields as a function of temperature, acidity, and precursor concentration; (2) measurement of the partitioning of the SOA species after their formation as a function of temperature and concentration; (3) investigation of the role of NOx in the formation of SOA; (4) quantification of the interactions among SOA precursors during SOA formation; (5) investigation of the chemical and physical changes (hygroscopicity) of primary and secondary organic particles during their atmospheric lifetime; (6) development of a state-of-the-art SOA formation and organic aerosol aging module (incorporating the findings from the proposed laboratory work) for use in current chemical transport models; (7) evaluation of the ability of the 3D chemical transport model to reproduce observed OC concentrations in the eastern US and estimated SOA concentrations in Western Pennsylvania, including revisions of mobile emissions based on recent Pittsburgh tunnel studies; and (8) investigation of the long-range transport of organic PM and the corresponding Eastern US source-receptor relationships.
Unique aspects of the proposed work include: the availability of a large environmental (smog) chamber that can operate at constant temperature in the 10-40°C temperature range, but also allows rapid temperature changes (2°C per minute); the combination of state-of-the-art methods for the measurement of the chemical composition, size distribution, and hygroscopic properties of organic PM; the investigation of the atmospheric aging of both the primary and secondary organic PM; the direct use of the laboratory results to improve the description of the corresponding processes in CTMs used for the design of emission control strategies; and finally the combination of expertise from five CMU research groups.
The project will quantify the dependence of the secondary organic formation on temperature, oxides of nitrogen and VOC/NOx, and on the presence of multiple VOCs or other SOA precursors. It will improve our understanding of the change in composition and hygroscopic properties of organics during their aging in the atmosphere. Our understanding of organic PM in the eastern US will be evaluated using the most comprehensive measurement dataset available and the organic aerosol model that will be developed. Finally, the contributions of different geographical areas and sources to the organic PM levels observed in the Eastern US will be quantified.