10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
A Multi-Season Investigation of Non-Combustion-Related Emissions of Gas-Phase Organic Compounds in Two Major U.S. Cities
PEEYUSH KHARE, Jenna Ditto, Taekyu Joo, Nga Lee Ng, Drew Gentner, Yale University
Abstract Number: 394 Working Group: Aerosol Chemistry
Abstract Emissions from combustion-related sources have historically dominated urban air pollution but non-combustion emissions are now playing an important role in determining the U.S. urban air quality (Khare and Gentner (2017), ACPD). Despite their growing significance, the magnitude, composition, secondary organic aerosol- and ozone- formation potential of non-combustion emissions in the atmosphere are largely understudied. In this study, we present results from our summer and winter air quality measurements in New York City, NY and Atlanta, GA with particular attention to the influence of non-combustion emissions. Gas- and particle-phase samples were collected at the New York State Department of Environmental Conservation (NYSDEC) site located in Queens, NY, a Manhattan facing residential building in Harlem, NYC and, at the Southeastern Aerosol Characterization (SEARCH) site near downtown Atlanta, GA. The collected samples were analyzed using traditional GC-MS, as well as using a very high resolution tandem mass spectrometer (i.e. MS×MS) employing atmospheric pressure chemical ionization and electrospray ionization inline with gas and liquid chromatographic separations, respectively. This provided molecular-level and structural characterization over a broad polarity and volatility range. A diverse suite of emitted organic compounds spanning across a wide polarity and volatility range is studied with special focus on under-characterized halogen- or phosphorus-containing organic pollutants and other intermediate volatility and semi-volatile organic compounds (IVOCs and SVOCs) whose direct and indirect health impacts are well documented. All prominent isomers are identified and reported, and are characterized by their accurate molecular formula, structural elements, and volatility. We report information on the range of urban concentrations of all measured compounds for comparison between the cities and seasons. Concentrations of each compound of interest are tested for least-squares correlation with CO concentrations, a common method for calculating emission since urban emissions of CO are mostly anthropogenic primary emissions, and provide a robust way to compare emissions between cities and scale up emissions with validated CO emissions inventories. Total urban emissions and individual concentrations are summarized by carbon number, compound class, and functionalities across the entire volatility span up to SVOCs. Measured compounds at each site are statistically evaluated for likely co-emissions or covariance via automated full dataset regressions in Igor Pro. We also collected and chemically characterized gasoline and diesel fuel samples from each city and season to constrain the contribution of motor vehicles to observed emissions using source apportionment methods. Our study aims to resolve major knowledge gaps in emissions inventories that are necessary for air quality models and comprehensive air quality policies in an era where non-combustion sources are emerging as key, prevalent factors in urban air quality.