Organic Aerosols in New York City — Insights from High-Resolution Aerosol Mass Spectrometry
Abstract
Submicron aerosol (PM1.0) was characterized in New York City during the Queens College Summer 2009 Field Intensive Study from July 14 - August 3 with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and complementary instrumentation. A specific aim of this study is to perform comparative AMS analyses to those performed during the 2001 summer campaign at the same site, when a substantial bimodal distribution in organic particle matter (PM) was observed, and to determine if this bimodal distribution in organic PM persists in the summer of 2009 and if its size/compositional attributes have changed. Drawing on HR-ToF-AMS spectra, we report on the composition and attribution of the small mean mode organic particles and observed changes in the composition of organic aerosol (OA) as a result of the introduction of low sulfur (15 ppm) diesel fuel. We have applied Positive Matrix Factorization (PMF) to the high resolution OA spectra and identified three major components: hydrocarbon-like OA (HOA) that correlates with black carbon and NOx, and represents urban primary emissions, highly oxygenated OA (OOA-I, mostly secondary OA) that correlates with sulfate, and freshly oxygenated OA (OOA-II) that correlates with nitrate and chloride. In addition, the elemental ratios (e.g., O/C, N/C, and H/C) were determined based on the high-resolution mass spectra. A pronounced morning peak was observed for the H/C ratio that is consistent with the diurnal pattern of HOA, and a significant noon peak for the O/C ratio due to photochemical production and aging of OA. Further details on sources and evolution of OA, formation and growth of aerosol particles are also discussed.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.A21C0172S
- Keywords:
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- 0305 ATMOSPHERIC COMPOSITION AND STRUCTURE / Aerosols and particles;
- 0345 ATMOSPHERIC COMPOSITION AND STRUCTURE / Pollution: urban and regional