Dr. Burke Leonce
PhD Graduate Geosciences
Structure-reactivity Mechanisms of Organic Matter Sorption and Photochemical Transformation in Aqueous Environments
Global change, such as land use, cover and management and changes in climate (e.g., wildfire activity), have perturbed the abiotic systems within the critical zone which has significant implications for the turnover potential of carbon. We conducted this research to improve our understanding of two important abiotic processes that influence organic matter (OM) preservation in aqueous environments — sorption and photodegradation. We also placed emphasis on the role of fire in carbon cycling dynamics and how climatic and anthropogenic alterations in wildfire regimes will affect carbon stocks. We found that the sorption of simple organic molecules onto metal oxides occurred via an outer-sphere mechanism involving multiple points of attachment and not via a high energy inner-sphere mechanism that is more commonly reported for OM-mineral interactions. Plant biomass type and its processing via charring were significant drivers of dissolved organic matter (DOM) photolability and its sorption to metal oxides. The photodegradation of DOM was captured by a three-component energy-based model that was used to predict the diurnal cycling of DOM across the state of Texas, United States in response to a wildfire scenario. In future studies we plan to improve the model by adding more plant species, exposure times and geographic locations.
What Faculty Say
Burke has a breadth of experiences that make him a well-rounded scientist, science writer and communicator. Burke Leonce makes everyone around him better. His scholarly research, teaching, and service are exemplary, yet he is approachable, cheerful, and generous to share his time and knowledge with his lab mates.