AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Impact of Fuel Type and Combustion Phase on the Chemical Composition of Particulate Matter Emissions from Wildland Fires
AMARA HOLDER, Johanna Aurell, Ingrid George, Brian Gullett, Venkatesh Rao, U.S. EPA
Abstract Number: 695 Working Group: Biomass Combustion: Emissions, Chemistry, Air Quality, Climate, and Human Health
Abstract EPA’s 2014 National Emission Inventory reports emissions by flaming and smoldering combustion phases. The mass fraction of each chemical constituent is derived from EPA’s SPECIATE database, which does not account for combustion phase and represents a minimal range of fuel types. Particulate matter emissions have exhibited wide variation across combustion conditions and fuel types. However, limited data exist on the variation of the chemical composition of particulate matter emissions and almost no information is available on the trace elemental composition. While these elements are emitted at low concentrations, the large amount of smoke generated by fires makes them a significant source to the atmosphere.
In this work, both field and laboratory fire sampling for a range of fuels (southeastern pine, western pine, tallgrass prairie, and peat) was used to understand how fuel characteristics and combustion conditions impact particulate matter emissions. A range of combustion conditions in the field were achieved by sampling emissions near back burns, head fires, and smoldering fuels. In the laboratory, air flow, fuel structure, and fuel moisture were varied to obtain a range of flaming and smoldering conditions with the same fuel. Particulate matter emission factors were strongly correlated with modified combustion efficiency and increased over an order of magnitude for smoldering versus flaming conditions for a single fuel type (5 – 50 g/kg). The minor elemental composition (e.g., K, Cl, Zn) exhibited poor correlation with combustion conditions and appeared to be more dependent on fuel type. These results demonstrate that both the fuel type and combustion conditions govern the particulate matter emissions from wildland fires and need to be accounted for in emissions inventories.
The views expressed in this abstract are those of the authors and do not necessarily reflect the views or policies of the U.S. Environmental Protection Agency.