Ground‐Based Field Measurements of PM_2.5 Emission Factors From Flaming and Smoldering Combustion in Eucalypt Forests

Abstract

In fire-prone areas such as southern Australia and parts of the United States, prescribed burning is a common fire management tool to reduce fuel load for wildfire suppression purposes. The burns are typically undertaken during calm and stable conditions when the burn extent and duration can be carefully controlled. This often coincides with poor atmospheric ventilation, leading to a buildup of smoke, which can impact air quality and human health. The low intensity of these burns also means that the plume is less buoyant and the main impact on local populations is due to emissions during the slow and prolonged smoldering combustion of heavy fuels. This study presents emission measurements of PM 2.5 at prescribed burns in eucalypt forests of southern Australia using a smoke collection method suitable for both flaming combustion of fine fuels and residual smoldering combustion of heavy fuels and logs. The median PM 2.5 emission factors (EFs) measured were 16.9-g/kg fuel during flaming combustion and 38.8-g/kg fuel during smoldering combustion. The correlation between PM 2.5 EFs and modified combustion efficiency highlights two distinct trends at low modified combustion efficiency, attributed to the distinct combustion processes of glowing char combustion and pyrolysis. Hence, two distinct relationships were developed that best fitted the measurements and that can be used to extrapolate measured EFs to a wider range of fuel and burning conditions. The results from this study addressed a gap in our knowledge of particle emissions during burns in eucalypt forests under different burning conditions and help to better forecast and manage air quality impacts from prescribed burns on nearby communities.

APIFLAME v2.0 trace gas and aerosol emissions from biomass burning: application to Portugal during the summer of 2016 and evaluation against satellite observations of CO (IASI) and AOD (MODIS)

“…Compared to experimental values for emission factors from Portuguese forest fires, values used here are quite conservative Alves et al (2011). report emission factors for evergreen forest fires in Portugal in May 2009 of 170±83 g kg −1 dry matter (DM) for CO, almost twice as large as those used here for temperate forests, of 14±4.5 g kg −1 for PM10, slightly lower than the value of 17.7 g kg −1 used here for temperate forest, and of 12±3.3 g kg −1 for PM2.5, in agreement with the value of 12.8 g kg −1 used here Reisen et al (2018). report emission factors of PM2.5 for prescribed burns in eucalypt forests of southern Australia of 16.9 g kg −1 DM during flaming combustion and 38.8 g kg −1 DM during smoldering combustion.…”

Emission of trace gases and aerosols from biomass burning – An updated assessment

“…Dry grassland fires, for example, are dominated by flaming combustion and a 10 rapid passage of the fire front, with little residual smoldering. Forest fires, on the other hand, especially those in fuels with relatively high fuel moisture and large diameters, have a long phase of residual smoldering combustion (RSC), during which larger-diameter fuels are consumed over time spans of up to several days (Ward and Hardy, 1991;Ward et al, 1992;Yokelson et al, 1997;Bertschi et al, 2003;Hao and Babbitt, 2007;Burling et al, 2011;Akagi et al, 2013;Geron and Hays, 2013;Urbanski, 2014;Reisen et al, 2018). The smoldering mode of combustion can become dominant in peatland fires, which often 15 proceed without a flaming phase and below ground .…”

“…CC BY 4.0 License. al., 2008;Soares Neto et al, 2009;Urbanski et al, 2009;Burling et al, 2011;Yokelson et al, 2013b;Liu et al, 2014;Urbanski, 2014;Collier et al, 2016;Coffey et al, 2017;Fortner et al, 2018;Hodgson et al, 2018;Reisen et al, 2018). Unfortunately, the correlation slopes between EFs and MCE vary considerably between studies in different fuels and burning environments, so that a general parameterization of EFs based on observed or modeled MCE remains problematic.…”

In situ measurements of trace gases, PM, and aerosol optical properties during the 2017 NW US wildfire smoke event

“…2b. Table 2 reports our study-average ratios (time-weighted) of BC/ CO, BC/ PM 2.5 , and PM 2.5 / CO and compares them to the limited measurements of wildfire smoke available in the lab and in the field (Liu et al, 2017;Sahu et al, 2012;Hobbs et al, 1996). Our BC/ CO ratio (0.0012) is a bit lower than the aircraft-measured averages of Sahu et al (2012) (0.0014) and Liu et al (2017) (0.0016) and the Selimovic et al (2018) estimate at the field average MCE for wildfires from Liu et al (2017, 0.0018).…”

“…Despite these important issues, many of the emissions from BB remain either understudied or completely unstudied. To date, most of the research on the emissions and evolution of smoke from US fires in the field has targeted prescribed fires (Burling et al, 2011;Akagi et al, 2013;Yokelson et al, 2013a;May et al, 2014;Müller et al, 2016), and while there are studies that probe trace gas and optical property emissions of wildfire smoke sampled in the field (Liu et al, 2017;Lindaas et al, 2017;Landis et al, 2017;Collier et al, 2016;Eck et al, 2013;Sahu et al, 2012;, much of the information is limited in temporal extent or incomplete chemically and fails to assess important issues such as the aging and evolution of smoke over varying and extended amounts of time, nighttime evolution and oxidation, or the contribution of constituents of increasingly recognized importance such as BrC (UV-absorbing OA), to name a few.…”