Combustion

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Formation mechanisms, emission controls; diesel/biofuel combustion

Quantifying the contribution o...

Title: 
Quantifying the contribution of emissions from combustion systems to ambient organic aerosols
Abstract: 

Motor vehicles, wood stoves, and other combustion systems are major sources of organic aerosols. This talk synthesizes results from recent smog chamber studies of motor vehicle emissions, open biomass burning emissions, and aircraft exhaust that highlight the chemistry and physics that control the contribution of these sources to atmospheric aerosol levels. The results reveal a picture of dynamic partitioning and dramatic changes with oxidation. This new picture alters our understanding of the contribution of combustion sources to urban and regional pollution and brings chemical transport model predictions into better agreement with field observations. An important finding is that secondary organic aerosol production often greatly exceeds the direct or primary emissions from most combustion systems; therefore, it must be included in any assessment of the contribution of combustion systems to ambient organic aerosol concentrations. However, existing atmospheric chemistry models cannot predict the observed secondary organic aerosol production. Low-volatility organic vapors emitted by combustion systems appear to be very important secondary organic aerosol precursors that are poorly accounted for in inventories and models. Therefore, new approaches will likely be required to include these vapors in models. The talk concludes by discussing the implications that the dynamic nature of these organic aerosol emissions has on source testing for both emission inventory development and regulatory purposes.

Presentation Type: 
Invited Presentation
Co-Authors
Author 1: 
Allen L. Robinson
Additional Authors: 
no more authors
Author Roles
Corresponding Author: 
Allen L. Robinson
Presenting Author: 
Allen L. Robinson

Particle emissions from combus...

Title: 
Particle emissions from combustion of western Mediterranean wood types: comparison between different appliances
Abstract: 

Residential wood combustion is now recognised as a major particulate matter (PM) source in many countries, including Portugal. The combustion appliances in use today provide variable combustion conditions resulting in large differences in the characteristics of the emitted particles. To fully characterise the particle emissions from a fireplace and a traditional cast iron stove, a series of experiments was conducted on the burning of prevalent Portuguese wood species (eucalyptus, pine, cork oak and golden wattle) and compared to those from a modern eco-labelled chimney stove. Analysis of the wood smoke included particle mass emission factors, organic and elemental carbon (OC/EC) content, ionic and elemental composition, and organic speciation by GC-MS. Emissions from the fireplace, cast iron stove and eco-labelled stove were, respectively, in the following ranges: 550-1122, 233-906 and 49-219 mg PM/MJ fuel burned (dry basis). Particle emissions from the traditional stove were about 7-fold higher than those from the eco-labelled appliance. In the fireplace and the old type stove, OC dominated the emissions, while more efficient combustion in the “chimney-type” stove contributed to 4 to 7-fold higher EC relative fractions in PM. Trace elements represented up to 2% of the PM mass, regardless the combustion appliance. However, a much higher ionic content was observed in emissions from the eco-labelled equipment. The ionic fraction is likely governed by the salt content of the fuel, as demonstrated in the golden wattle emissions. Levoglucosan was detected at average concentrations of 269, 222 and 215 mg/gOC in the smoke emitted from the fireplace, traditional stove and modern stove, respectively. The hardwood smoke contains more substituted syringols than the softwood smoke, and the resin acids and diterpenoids are only present in softwood smoke. These results suggest that differences in the source profiles between wood types merit consideration in source apportionment calculations using organic tracers.

Presentation Type: 
Poster
Co-Authors
Author 1: 
Celia A. Alves
Author 2: 
Catia Gonçalves
Author 3: 
Patricia Fernandes
Author 4: 
Ana Calvo
Author 5: 
Luis Tarelho
Author 6: 
Teresa F.V. Nunes
Author 7: 
Casimiro A. Pio
Author 8: 
Hans Puxbaum
Additional Authors: 
no more authors
Author Roles
Corresponding Author: 
Celia A. Alves
Presenting Author: 
Celia A. Alves