A Comparison of Mass-Based Emission Factors from Laboratory Combustion of Boreal and Sub-Tropical Peat

Abstract:

Peatlands cover approximately 3% of the Earth’s surface, but account for approximately one-third of terrestrial soil carbon. This carbon is also much older, collected over hundreds to thousands of years, than other commonly encountered wildfire fuels such as Ponderosa Pine (i.e., years to decades). Due to the moisture and mineral content of peat it has a propensity to smolder, unlike Ponderosa Pine which has an intense flaming period when burning. To better understand the emission from peat fires, in comparison to Ponderosa Pine, a series of experiments were performed in the 8 m³ combustion chamber located at the Desert Research Institute in Reno, NV. Peat from Alaska and Florida (USA) and Siberia (Russia) were burned at two moisture content levels (25 & 50%). Ponderosa Pine needles from Sierra Nevada sites were burned at one moisture content level (8.2%). Real-time measurements included gaseous carbon monoxide (CO), carbon dioxide (CO₂), oxides of nitrogen (NO_x = NO + NO₂), and ozone (O₃) concentration, as well as particulate matter (PM) mass, size distribution, and black carbon concentration. In addition, Teflon-membrane and quartz-fiber filters as well as Teflon-impregnated glass fiber (TIGF) filters followed by XAD-4 cartridges were collected for detailed PM chemical speciation. Changes in fuel mass and combustion temperature were continuously monitored during each experiment. We will present a comparison of mass-based emission factors of inorganic gases, PM and black carbon mass concentrations, organic and elemental carbon, and a number of intermediate-volatility (300<saturation mass concentration, C*<3x10⁶ μg m^-3) and semi-volatile (0.3<C*<300 μg m^-3) polar organic compounds (POCs) in gas- and particle-phases. Implications for secondary organic aerosol formation in smoke plumes will be discussed. Because fire regimes are expected to increase, an improved understanding of their emissions will enable us to better forecast their impacts on local and regional climate and air quality.