AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Novel Smog Chamber Studies of Wood Burning Emissions at Low Temperatures
EMILY BRUNS, Imad El Haddad, Stephen Platt, Brice Temime-Roussel, Dogushan Kilic, Jay Slowik, Anaïs Detournay, Luka Drinovec, Grisa Mocnik, Nicolas Marchand, Urs Baltensperger, Andre Prévôt, Paul Scherrer Institute
Abstract Number: 198 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Domestic wood burning is a significant source of atmospheric aerosols, particularly in winter, as it is a common heating method in regions with moderate and cold climate. Nevertheless, uncertainties remain in the magnitude and characteristics of wood burning emissions. Discrepancies exist between the organic mass to black carbon ratio (OM/BC), possibly because previous laboratory studies were conducted at higher-than-ambient winter temperatures. In addition to primary emissions, previous experiments show that oxidation of gas phase wood burning emissions produces compounds with sufficiently low volatility to partition to the particles and form secondary organic aerosol (SOA). However, relatively little is known about these secondary aerosols and the role of ambient temperature and humidity in their formation.
We report results from smog chamber experiments characterizing primary and secondary wood burning products performed at representative winter temperatures for the first time. Primary emissions were diluted to atmospherically-relevant concentrations and injected into the chamber, where OH photochemistry initiated the formation and aging of secondary products. Experiments were performed at 263K and 288K, and at 50% and 90% relative humidity. Effects of wood loading in the oven were also investigated. The non-refractory aerosol composition and quantities were determined by aerosol mass spectrometry. BC quantification and the effect of organic coatings on BC optical properties were determined using Aethalometers with and without a thermal desorber in the sampling line. Measurements of gas phase species were made with a suite of instruments, including a proton transfer reaction mass spectrometer.
Conducting experiments at lower temperature resulted in higher primary OM/BC, enhanced SOA/BC and better agreement with ambient measurements. High fuel loading generated significantly more polycyclic aromatic hydrocarbons (PAHs) compared to average loadings. As PAHs and their oxidation products have deleterious health effects, this is a significant finding to mitigate negative wood burning impacts by improving oven operation protocols.