Unraveling the Impact of Wildfire Smoke on Canopy-Derived Dissolved Organic Matter and Dissolved Black Carbon Dynamics

• Ryan Kim, Environmental Engineering, University of Delaware

• Yu-ping Chin, Department of Civil and Environmental Engineering, University of Delaware

Unraveling the Impact of Wildfire Smoke on Canopy-Derived Dissolved Organic Matter and Dissolved Black Carbon Dynamics

Ryan Kim¹, Robyn O’Halloran¹, Delphis F. Levia^1,2,3,  Yu-Ping Chin¹

¹ Dept. of Civil & Environmental Engineering, University of Delaware, Newark, DE, USA

² Dept. of Geography & Spatial Sciences, University of Delaware, Newark, DE, USA

³ Dept. of Plant & Soil Sciences, University of Delaware, Newark, DE, USA

Wildfires annually consume over 460 million hectares of the Earth’s land surface, emitting substantial CO₂ and black carbon (BC) into the atmosphere. BC, a byproduct of incomplete combustion, profoundly affects the carbon cycle as well as human and ecosystem health. A portion of BC, termed dissolved BC (DBC), is solubilized and transported into inland waters, especially during precipitation events. Forested catchments play a crucial role in modifying the chemical composition of rainfall, enriching it with canopy-derived dissolved organic matter. Throughfall and stemflow serve as important pathways for the transport of DOM to the forest floor during precipitation events. Despite the importance of canopy-derived DOM in terrestrial carbon cycles, factors influencing its quantity and composition remain inadequately understood. We investigated the presence of DBC derived from the stemflow of four trees in a temperate deciduous forest affected by smoke, originating from distal wildfires, namely Betula lenta L. (sweet birch), Fagus grandifolia Ehrh. (American beech), Liriodendron tulipifera L. (yellow poplar), and Pinus rigida Mill. (pitch pine). This study quantifies DBC in stemflow affected by smoke.   A liquid chromatography mass spectrometry (LCMS) methodology for the analysis and quantification of DBC content in stemflow DOM was developed. The results from this study are used to assess the ubiquity, amount, and variability of DBC in stemflow DOM. By elucidating the mechanisms through which smoke impacts stemflow DOM and its relation to BC transport, this study contributes to a better understanding of the complex interactions between wildfires and terrestrial carbon cycling, while also providing insights into atmospherically transported chemicals via stemflow.