Impact/Purpose:

Our objective is to extend our recently-developed volatility basis set to maturity with a succession of experiments coupled to module development for air-quality models. An issue of great importance in the Eastern U.S. is regional transport of SOA and its attendant vapors, and a major hypothesis to be examined in this proposed research is how the aging of this combination of vapors and SOA influences SOA behavior through long-range transport.

Description:

Secondary Organic Aerosols are a major, possibly dominant, source of organic PM_2.5 that remain enigmatic. Enormous progress has been made in the past 15 years regarding SOA formation, starting with recognition that most SOA products are semivolatile, continuing to a formal description of the thermodynamics of SOA mixtures from Pankow and Odum, and culminating in recent findings that condensed-phase chemistry can significantly alter SOA composition and possibly volatility. However, there remain very substantial gaps between model predictions and observations in almost all facets of organic aerosol behavior, including the primary-secondary and biogenic-anthropogenic ratios.

URLs/Downloads:

2008 Progress Report

Final Progress Report

Record Details:

Record Type:PROJECT( ABSTRACT )

Start Date:09/01/2007

Completion Date:08/31/2008

Record ID: 200541

Show Additional Record Data

Related Organizations:

Role :OWNER

Organization Name :AERODYNE RESEARCH INC.

Mailing Address :45 Manning Road

Citation :Billerica

State :MA

Zip Code :1821



Role :OWNER

Organization Name :CARNEGIE MELLON UNIVERSITY

Mailing Address :5000 Forbes Ave

Citation :Pittsburgh

State :PA

Zip Code :15213

Project Information:

Approach :

The proposed experiments will quantify SOA formation and aging from terpenes and aromatic compounds in the CAPS temperature-controlled smog chamber. Advanced instrumentation, including high-resolution thermal desorption Aerosol Mass Spectrometry (HR- TD-AMS) and techniques including dilution sampling and thermal denuder volatility measurement, will permit near mass closure while separating products by volatility. Data will be obtained as functions of key variables, including NO_x levels, humidity, UV illumination, and reaction temperature. First-generation product distributions will be fit with the volatility basis set; extended exposure to oxidants will constrain “volatility operators” that describe the aging of this volatility distribution due to both gas and condensed-phase chemistry. The results will be incorporated in a compact SOA Integrated Aging Module for use in air quality models. The module will be implemented in PMCAMx will be easy to implement in CMAQ. After model evaluation against supersite and network data, model runs will evaluate the role of multi-generation chemistry and NO_x controls on SOA levels in areas strongly influenced by long-range transport, such as the Eastern U.S.

Cost :$599,990.00

Project IDs:

ID Code :R833746

Project type :EPA Grant