Emission factors and evolution of SO2 measured from biomass burning during FIREX-AQPamela S. Rickly1,2, Hongyu Guo1,3, Benjamin A Nault1,3, Pedro Campuzano-Jost1,3, Jose L. Jimenez1,3, Andrew Rollins2

1Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA2Chemical Sciences Laboratory, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USA

3Department of Chemistry, University of Colorado, Boulder, CO 80309, USA

INTRODUCTION• Sulfate aerosols cool the Earth’s surface• They produce harmful effects for human health• Sulfate is formed through the oxidation of SO2

• Biomass burning emits large concentrations of SO2

• Large uncertainty in SO2 emission factors have been reported

• Conversion mechanism of SO2 to sulfate remains uncertain creating underprediction of sulfate in atmospheric models by up to a factor of two (Wang et al., 2016; Shao et al., 2019; Wang et al., 2014).

EMISSION FACTORS• Emission factor data during flaming conditions

agree well with compiled field values when combined based on environmental characteristics.

• Large variation in temperate forest data suggests a more limited definition may be necessary.

• Overall, difference between flaming and smoldering emissions is unclear with flaming stage = 0.62 ± 0.27 g kg-1 and smoldering stage = 0.56 ± 0.26 g kg-1.

MODELLING• F0AM mechanism developed with the inclusion of

O3, H2O2, NO2, and HCHO aqueous phase S(IV) oxidation.

• Produces S(IV) pH dependence • Produces pH dependence of sulfate production as

previously observed for each oxidant• Reproduces downwind SO2 trends within 10%

and sulfate trends within 15% for the Williams Flats fire.

• O3 + SO32- is the largest contributor to sulfateproduction.

• Laser-induced fluorescence used to measure SO2

• Sulfate measurements from the aerosol mass spectrometry group

• DC-8 platform used for measurements of biomass burning smoke plumes

• F0AM 0-D box model used for modelling conversion of SO2 to sulfate in a more neutral environment (pH 7) compared to urban (pH <3)

ReferencesAndreae, M. O.: Emission of trace gases and aerosols from biomass burning – an updated assessment, Atmos. Chem. Phys., 19, 8523–8546, https://doi.org/10.5194/acp-19-8523-2019, 2019.Wang, G., Zhang, R., Gomez, M. E., Yang, L., Zamora, M. L., Hu, M., Lin, Y., Peng, J., Guo, S., Meng, J., Li, J., Cheng, C., Hu, T., Ren, Y., Wang, Y., Gao, J., Cao, J., An, Z., Zhou, W., Li, G., Wang, J., Tian, P., Marrero-Ortiz, W., Secrest, J., Du, Z., Zheng, J., Shang, D., Zeng, L., Shao, M., Wang, W., Huang, Y., Wang, Y., Zhu, Y., Li, Y., Hu, J., Pan, B., Cai, L., Cheng, Y., Ji, Y., Zhang, F., Rosenfeld, D., Liss, P. S., Duce, R. A., Kolb, C. E., and Molina, M. J.: Persistent sulfate formation from London Fog to Chinese haze, PNAS, 113 (48) 13630-13635, https://doi.org/10.1073/pnas.1616540113Shao, J., Chen, Q., Wang, Y., Lu, X., He, P., Sun, Y., Shah, V., Martin, R. V., Philip, S., Song, S., Zhao, Y., Xie, Z., Zhang, L., and Alexander, B.: Heterogeneous sulfate aerosol formation mechanisms during wintertime Chinese haze events: air quality model assessment using observations of sulfate oxygen isotopes in Beijing, Atmos. Chem. Phys., 19, 6107–6123, https://doi.org/10.5194/acp-19-6107-2019, 2019.Wang, Y., Q. Q. Zhang, J. Jiang, W. Zhou, B. Wang, K. He, F. Duan, Q. Zhang, S. Philip, and Y. Xie (2014), Enhanced sulfate formation during China’s severe winter haze episode in January 2013 missing from current models, J. Geophys. Res. Atmos., 119, 10,425–10,440, doi:10.1002/2013JD021426.Photo by https://unsplash.com/photos/j7wXfhojXtk

METHODS

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