Investigating the Relationship between Oxidative Potential and Absorption Strength of Biomass-Burning Organic Aerosols
YUEZHI (AUGUST) LI, Joseph V. Puthussery, Rajan K. Chakrabarty, Washington University in St. Louis
Abstract Number: 538
Working Group: Aerosol Processes and Properties in Changing Environments in the Anthropocene
Abstract
Organic aerosols emitted from biomass-burning events impose profound impacts on Earth’s radiative budget and are a major contributor to ambient particulate pollutants. When inhaled, these particles can generate excess reactive oxygen species that cause oxidative stress, leading to respiratory diseases. The capability of aerosols to induce oxidative stress is defined as their oxidative potential (OP).
In this study, we aim to investigate the relationship between OP and absorptivity of biomass-burning aerosols. We generated the aerosols in a combustion chamber by burning three prominent biofuels in North America: white sage, Douglas fir, and cheatgrass. The particles were collected on filters and extracted into water and methanol. An integrated photoacoustic nephelometer, operated at 405, 721, and 1047 nm, measured the ensemble-scale aerosol light absorption. For the soluble organic components, the absorption was measured using an ultraviolet-visible spectrophotometer, and the OP was quantified using in vitro dithiothreitol (DTT) assay. Preliminary results show that the OP of water-soluble components increased with total and water-soluble mass absorption coefficients (MAC) across all wavelengths, with sage aerosols ranked the lowest and grass aerosols the highest. This possibly suggests a correlation between the absorptivity and toxicity of water-soluble biomass-burning aerosols. However, this trend did not hold for methanol extracts. At 405 nm, the methanol-soluble organics from sage were the most absorptive (MACsage,methanol,405 = 0.5 m2/g) but least toxic. In contrast, the methanol-soluble components from fir and grass were less absorbing with MAC values of 0.2 and 0.4 m2/g but contributed ~21% and ~33% higher to OP, respectively, compared to sage. More replicates are required to consolidate these results. This study will provide insights into the link between health effects, solubility, and absorptivity of biomass-burning aerosols and could spur new mitigation strategies for the affected populations.