1. Nos Commanditaires : IRIC 18 mars, 2014 19h00 Salle S1-151 Pavillon Jean-Coutu Université de Montréal

2. IRIC 18 mars, 2014 19h00 Salle S1-151 Pavillon Jean-Coutu Université de Montréal Patrick Hayes Professor, Analytical spectroscopy & environmental analyses Chemistry department, U de M Atmospheric Aerosol Composition and Sources in Los Angeles Studied by In-Situ Mass Spectrometry Atmospheric aerosols have a well-known impact on human health and climate as highlighted in the most recent Intergovernmental Panel on Climate Change report published in 2013. However, atmospheric aerosols remain poorly characterized because, in part, of their chemical complexity. Specifically, the organic fraction of aerosols is composed of thousands of compounds that have a wide range of sources in the environment (e.g. diesel combustion and cooking emissions). This seminar will describe mass spectrometry measurements of organic aerosols carried out near Los Angeles as part of the CalNex field campaign. Five distinct chemical classes of organic aerosol are identified, and using the measured elemental compositions, mass spectra, and correlations with tracers each class can be associated with specific sources. Important findings include the observation that the total organic aerosol mass concentration is dominated by “secondary” organic aerosols, which are composed of the low volatility oxidation products of gaseous emissions.

3. Our Sponsors: IRIC March 18, 2014 19h00 Room S1-151 Pavillon Jean-Coutu Université de Montréal

4. IRIC March 18, 2014 19h00 Room S1-151 Pavillon Jean-Coutu Université de Montréal Patrick Hayes Professor, Analytical spectroscopy & environmental analyses Chemistry department, U de M Atmospheric Aerosol Composition and Sources in Los Angeles Studied by In-Situ Mass Spectrometry Atmospheric aerosols have a well-known impact on human health and climate as highlighted in the most recent Intergovernmental Panel on Climate Change report published in 2013. However, atmospheric aerosols remain poorly characterized because, in part, of their chemical complexity. Specifically, the organic fraction of aerosols is composed of thousands of compounds that have a wide range of sources in the environment (e.g. diesel combustion and cooking emissions). This seminar will describe mass spectrometry measurements of organic aerosols carried out near Los Angeles as part of the CalNex field campaign. Five distinct chemical classes of organic aerosol are identified, and using the measured elemental compositions, mass spectra, and correlations with tracers each class can be associated with specific sources. Important findings include the observation that the total organic aerosol mass concentration is dominated by “secondary” organic aerosols, which are composed of the low volatility oxidation products of gaseous emissions.