Comparison of Urban and Biogenic Influences on Aerosol Composition at a Semirural Site in Southern Ontario
Abstract
Intensive gas and particle measurements were conducted at the Center for Atmospheric Research Experiments (CARE) in Egbert, Ontario, as part of the Egbert 2007 summer field campaign. The CARE site is located approximately 70 km north of Toronto and is influenced both by urban outflow and biogenic emissions. As such, this location offers an ideal venue to compare the contributions of anthropogenic and biogenic sources to the aerosol at a semirural location. Mass spectra from an Aerodyne time-of-flight mass spectrometer (AMS) were deconvolved into factors related to chemical composition and emissions sources using positive matrix factorization. Factors were obtained relating to anthropogenic and biogenic secondary organic aerosol (SOA) formation, as well as processed and unprocessed primary anthropogenic emissions. Correlation of these factors with measurements of VOC concentrations by a proton transfer mass spectrometer (PTRMS) and a Hantsch monitor enables the factors to be interpreted in terms of the photochemical age of the particles and the gaseous precursors and/or reaction byproducts relating to particle sources and processing. In addition to the organic species, the urban outflow yielded high concentrations of particulate sulfate and a prominent diurnal cycle of nitrate concentrations, peaking shortly before dawn. Due to the complexity of the sources influencing the CARE site, particle mixing state is important in determining source contributions. The mixing state was determined from the AMS single particle mass spectra, triggered by signals from an optical scattering module. AMS collection efficiency, which is related to particle phase, was estimated by comparison with a Particle-Into- Liquid-Sampler (PILS) system.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AGUFM.A24C..07S
- Keywords:
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- 0305 Aerosols and particles (0345;
- 4801;
- 4906);
- 0345 Pollution: urban and regional (0305;
- 0478;
- 4251);
- 0394 Instruments and techniques