Brown Carbon Emissions from Biomass Burning under Simulated Wildfire and Prescribed-Fire Conditions

Chase K. Glenn; Omar El Hajj; Zachary McQueen; Ryan P. Poland; Robert Penland; Elijah T. Roberts; Jonathan H. Choi; Bin Bai; Nara Shin; Anita Anosike; Kruthika V Kumar; Muhammad Isa Abdurrahman; Pengfei Liu; I. Jonathan Amster; Geoffrey D. Smith; Steve Flanagan; Mac A. Callaham; E. Louise Loudermilk; Joseph J. O'Brien; Rawad Saleh

doi:10.1021/acsestair.4c00089

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Brown Carbon Emissions from Biomass Burning under Simulated Wildfire and Prescribed-Fire Conditions

Formally Refereed

Authors:

Chase K. Glenn, Omar El Hajj, Zachary McQueen, Ryan P. Poland, Robert Penland, Elijah T. Roberts, Jonathan H. Choi, Bin Bai, Nara Shin, Anita Anosike, Kruthika V Kumar, Muhammad Isa Abdurrahman, Pengfei Liu, I. Jonathan Amster, Geoffrey D. Smith, Steve Flanagan, Mac A. Callaham, E. Louise Loudermilk, Joseph J. O'Brien, Rawad Saleh

Year:

2024

Type:

Scientific Journal

Station:

Southern Research Station

DOI:

https://doi.org/10.1021/acsestair.4c00089

Source:

ACS ES&T Air

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Abstract

We investigated the light-absorption properties ofbrown carbon (BrC) as part of the Georgia Wildland-FireSimulation Experiment. We constructed fuel beds representativeof three ecoregions in the Southeastern U.S. and varied the fuel-bed moisture content to simulate either prescribed fires ordrought-induced wildfires. Based on decreasing fire radiativeenergy normalized by fuel-bed mass loading (FREnorm), thecombustion conditions were grouped into wildfire (Wild),prescribed fire (Rx), and wildfire involving duff ignition (Wild-Duff). The emitted BrC ranged from weakly absorbing (WildDuff)to moderately absorbing (Rx and Wild) with the imaginary part ofthe refractive index (k) values that were well-correlated withFREnorm. We apportioned the BrC into water-soluble (WSBrC)and water-insoluble (WIBrC). Approximately half of the WSBrC molecules detected using electrospray-ionization massspectrometry were potential chromophores. Nevertheless, k of WSBrC was an order of magnitude smaller than k of WIBrC.Furthermore, k of WIBrC was well-correlated with FREnorm while k of WSBrC was not, suggesting different formation pathwaysbetween WIBrC and WSBrC. Overall, the results signify the importance of combustion conditions in determining BrC light-absorption properties and indicate that variables in wildland fires, such as moisture content and fuel-bed composition, impact BrClight-absorption properties to the extent that they influence combustion conditions.

Keywords

wildland fire, smoke, combustion conditions, fire radiative energy, organic aerosol, chromophores, light absorption

Citation

Glenn, Chase K.; El Hajj, Omar; McQueen, Zachary; Poland, Ryan P.; Penland, Robert; Roberts, Elijah T.; Choi, Jonathan H.; Bai, Bin; Shin, Nara; Anosike, Anita; Kumar, Kruthika V.; Abdurrahman, Muhammad Isa; Liu, Pengfei; Amster, I. Jonathan; Smith, Geoffrey D.; Flanagan, Steven; Callaham, Mac A.; Loudermilk, Eva L.; O’Brien, Joseph J.; Saleh, Rawad. 2024. Brown Carbon Emissions from Biomass Burning under Simulated Wildfire and Prescribed-Fire Conditions. ACS ES&T Air. 3(10): 2-. https://doi.org/10.1021/acsestair.4c00089.