Emissions from Laboratory Combustion of Wildland Fuels:  Emission Factors and Source Profiles

Abstract

Combustion of wildland fuels represents a major source of particulate matter (PM) and light-absorbing elemental carbon (EC) on a national and global scale, but the emission factors and source profiles have not been well characterized with respect to different fuels and combustion phases. These uncertainties limit the accuracy of current emission inventories, smoke forecasts, and source apportionments. This study investigates the evolution of gaseous and particulate emission and combustion efficiency by burning wildland fuels in a laboratory combustion facility. Emission factors for carbon dioxide (CO2), carbon monoxide (CO), total hydrocarbon (THC), nitrogen oxides (NO(x)), PM, light extinction and absorption cross sections, and spectral scattering cross sections specific to flaming and smoldering phases are reported. Emission factors are generally reproducible within +/- 20% during the flaming phase, which, despite its short duration, dominates the carbon emission (mostly in the form of CO2) and the production of light absorption and EC. Higher and more variable emission factors for CO, THC, and PM are found during the smoldering phase, especially for fuels containing substantial moisture. Organic carbon (OC) and EC mass account for a majority (i.e., > 60%) of PM mass; other important elements include potassium, chlorine, and sulfur. Thermal analysis separates the EC into subfractions based on analysis temperature demonstrating that high-temperature EC (EC2; at 700 degrees C) varies from 1% to 70% of PM among biomass burns, compared to 75% in kerosene soot. Despite this, the conversion factor between EC and light absorption emissions is rather consistent across fuels and burns, ranging from 7.8 to 9.6 m2/g EC. Findings from this study should be considered in the development of PM and EC emission inventories for visibility and radiative forcing assessments.

An Efficient Multipollutant System for Measuring Real-World Emissions from Stationary and Mobile Sources

“…Around 12:45:05, the fire entered the smoldering phase, and all pollutant concentrations decreased when the MCE reached a minimum of ~0.80. A gradual increase of MCE from the second half of the smoldering phase has been observed in earlier studies (Hays et al, 2005;Chen et al, 2007;Hosseini et al, 2010) and is probably due to the decrease of CO concentrations as the smoldering temperature decreases toward the end of the burn. The BC/PM 2.5 from the microaethalometer and DustTrak DRX decreased continuously from the beginning of the transition phase, indicating a decrease in the fraction of PM that absorbs light at 880 nm.…”

The Indoor and Outdoor Carbonaceous Pollution during Winter and Summer in Rural Areas of Shaanxi, China

“…The high OC/EC ratios can be attributed to the presence of emissions of carbonaceous aerosols from sources with a high OC/EC ratio. Although OC/EC ratios can vary substantially among different source categories (Mazzera et al, 2001;Chen et al, 2007;Han Y.M. et al, 2008), the occurrence of some extremely high OC/EC ratios (> 20) in our samples can best be explained by the impacts of burning straws and corncobs used for heating and cooking in winter.…”

Chemical characterization of fine particulate matter emitted by peat fires in Central Kalimantan, Indonesia, during the 2015 El Niño

“…Many of these studies primarily focused on chemically characterizing gaseous emissions (Benner, 1977;Chen et al, 2007;Christian et al, 2003;Geron and Hays, 2013;May et al, 2014;McMahon et al, 1980;Ward, 1990;Hatch et al, 2015;Stockwell et al, 2015;Stockwell et al, 2014;George et al, 2016;Black et al, 2016;Iinuma et al, 2007;Yokelson et al, 1997) while fewer focused on the PM fraction Fujii et al, 2014;Fujii et al, 2015a;Iinuma et al, 2007). Peatland fire emissions were not considered in the 5 biomass burning emission inventory published by Andreae and Merlet (2001).…”