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Hygroscopicity and Cloud Condensation Nuclei Activity of Fresh and Aged Biomass Burning Particles

Year: 2026
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Biomass burning (BB) is a major source of atmospheric particles and trace gases, influencing climate change, air quality, and human health. During the Georgia Wildland-Fire Simulation Experiment, we measured the hygroscopicity (κ) and size-resolved cloud condensation nuclei (CCN) activity of BB particles from controlled burns of fuel beds representative of three ecoregions in Georgia, United States. Primary BB particles were predominantly organic, and photooxidation in an oxidation flow reactor produced secondary organic aerosol (SOA) in a new nucleation mode while transforming primary organic aerosol (POA) into oxidized POA (OPOA) in the pre-existing accumulation mode. We measured hygroscopic growth from 20% to 90% relative humidity using a quartz crystal microbalance and assessed size-resolved CCN activity for particles from 30 to 350 nm at supersaturation between 0.13% and 0.99%. We found that the hygroscopicity parameter of OPOA (κ OPOA = 0.10–0.19) was higher than that of POA (0.04–0.10), reflecting the influence of heterogeneous oxidation, whereas the hygroscopicity parameter of SOA (κ SOA = 0.07–0.14) fell between the two. Both fresh and aged BB particles displayed size-dependent κ values and evidence of external mixing, likely because of complex emission characteristics of fuel beds and size-dependent deposition processes. Growth factor-derived and CCN-derived κ values were consistent when accounting for such heterogeneity. A strong positive correlation was found between the mass-averaged κ and O/C ratio, described by the regression κ = 0.31 ± 0.02(O/C) – 0.05 ± 0.02, which broadly agrees with previous findings for a wide range of laboratory SOA and ambient oxidized organic aerosols. This suggests the potential applicability of a generalized hygroscopicity parameterization across organic aerosols within acceptable uncertainty. Our results highlight the role of BB particles as significant CCN sources during atmospheric aging and emphasize the importance of heterogeneous oxidation in physicochemical evolution of BB particles.
Source: ACS ES&T Air
DOI: 10.1021/acsestair.5c00331
Authors: Bin Bai, Aishwarya Singh, Tianchang Xu, Christos Stamatis, Kezhou Lu, Nara Shin, Chase K. Glenn, Omar El Hajj, Kruthika V. Kumar, Anita Anosike, Muhammad Isa Abdurrahman, Sachin S. Gunthe, Joseph J. O’Brien, Gabriel Isaacman-VanWertz, Rawad Saleh, Nga L. Ng, Pengfei Liu
Institutions: Georgia Institute of Technology, Indian Institute of Technology Madras, Virginia Tech, Purdue University West Lafayette, University of Georgia, Aerodyne Research, US Forest Service, United States Department of Agriculture, Southern Research Station
Language: English
Open Access status: hybrid
Estimated APC paid: $4,500
Funders: National Science Foundation, Research Institute, Georgia Institute of Technology, Georgia Institute of Technology, Division of Chemistry, Division of Atmospheric and Geospace Sciences, Congressionally Directed Medical Research Programs
Awards: MRI: Acquisition of a Chemical Ionization Mass Spectrometer for Measuring Organic Compounds at the Interfaces of Earth’s Systems, G2672601081, G3928530942, Culprit Burning Pollutant Associated with Alpha-Synuclein-Related ADRD, Collaborative Research: A Nitrate Radical Oxidation Flow Reactor: Development and Use in Laboratory and Field Studies, G4879137991, G6290200611, G68941308, Laboratory Chamber Studies on Gas-Phase Photooxidation and Aqueous Chemistry of Phenols and Methoxyphenols in Biomass Burning Organic Aerosol Formation, CAREER: Toward Improved Parameterizations of Brown Carbon in Wildland-Fire Emissions, CAREER: Understanding the Fate of Reactive Organic Carbon in the Atmosphere
OpenAlex ID: W7128808353
FWCI: 6.147
Cites: 62
Cited by: 2
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