Comparative Assessment of Organic Aerosols from Biomass Combustion Based on Controlled Laboratory Studies vs Field Studies Using the Example of Sugar Cane Combustion

Elena Hartner, THOMAS GRÖGER, Nadine Gawlitta, Sandra Piel, Hendryk Czech, Genna-Leigh Geldenhuys, Jürgen Orasche, Petri Tiitta, Pasi Yli-Pirilä, Miika Kortelainen, Patricia Forbes, Olli Sippula, Thomas Adam, Ralf Zimmermann, Helmholtz Zentrum München and University of Rostock

     Abstract Number: 518
     Working Group: Combustion

Abstract
Agricultural biomass combustion aerosols, particularly biomass-burning organic aerosols (BBOA), represent a significant global aerosol source. Controlled burning practices, such as those employed in sugar cane harvesting to manage surplus biomass, contribute substantially to this aerosol burden. While regulatory measures have been implemented to mitigate risks to workers and local communities, these burnings still exert substantial impacts on human health, the environment, and the climate, both regionally and globally.

Understanding the aerosol formation resulting from such fires necessitates either controlled laboratory investigations or field measurements during actual burning events. This study aims to evaluate the comparability of findings from these approaches through direct comparison. Field experiments involved authentic open-field burning conducted at five distinct sugar cane farms in South Africa. Additionally, controlled laboratory experiments, simulating sugar cane burning, were conducted in batches using dried sugar cane leaves sourced from the same origin. These experiments were carried out at the aerosol physics, chemistry, and toxicology research unit (ILMARI) of the University of Eastern Finland.

Aerosol sampling was conducted using quartz fiber filters, adsorber tubes, and portable multichannel polydimethylsiloxane denuders. Analytical techniques, including one and comprehensive two-dimensional gas chromatography mass spectrometry, were employed to assess the chemical composition of the collected samples. Chemical fingerprints obtained were analyzed using targeted and nontargeted approaches.

Both experimental setups revealed a complex chemical composition of biomass combustion emissions, encompassing compounds originating from the pyrolysis of (hemi)cellulose and lignin. Notably, field experiments detected additional organic compounds such as pyridine and oxime derivatives, methoxyphenols, methoxybenzenes, and triterpenoids. In contrast, laboratory experiments only partially replicated the complexity observed in real combustion events.

The results highlight disparities between field and laboratory experiments, attributed to differences in combustion conditions, fuel composition, and atmospheric processing. These findings underscore the importance of considering such factors when interpreting results and designing future studies in this field.