AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Source Apportionment of Organic Aerosols and VOCs Near Fort Worth, TX
ANDREW RUTTER, Basak Karakurt Cevik, Longwen Gong, Kabin Shakya, Caroline Gutierrez, Melanie Calzada, Saewung Kim, Robert Griffin, James Flynn, Barry Lefer, Rice University
Abstract Number: 586 Working Group: Urban Aerosols
Abstract An air quality study of the outflow from the Dallas-Fort Worth, TX, metropolitan area was conducted in June of 2011 at a downwind, rural location northwest of Fort-Worth. Measurements of the composition of organic aerosols and volatile organic compounds were made between June 4 and June 30, 2011. Organic aerosol composition was determined using an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer. Positive Matrix Factorization (PMF) was used to separate the organic aerosols measured into hydrocarbon-like organic aerosols (HOA) and two classes of oxidized organic aerosols (OOA 1 and 2), where OOA2 was the more oxidized of the two classes. HOA constituted 12% of measured OA mass on average, while the oxidized classes OOA1 and 2 constituted 43% and 41%, respectively.
Volatile organic compounds were measured using an Auto Gas Chromatograph operated by the Texas Commission for Environmental Quality (TCEQ) and a proton-transfer reaction mass spectrometer operated by our research team. The VOC measurements were combined with measurements of ozone, carbon monoxide, and nitrogen oxides, and were entered into a PMF model separate from that used for the organic aerosols. This PMF model identified six source categories: Natural Gas, Fuel Evaporation, Motor Vehicles, Biogenics, and two oxidation factors.
Relationships between the organic aerosol and VOC source factors were observed, allowing a qualitative assessment of whether the organic aerosols measured originated from anthropogenic or biogenic sources.