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How do wildfire severity and post-fire precipitation influence fate and transport of pyrogenic organic carbon and nitrogen in terrestrial-aquatic interfaces?

Active Dates 9/1/2022-8/31/2025
Program Area Environmental Systems Science
Project Description
Wildfire significantly changes the composition and quantity of forest biomass, converting lignin and polysaccharide rich and relatively degradable carbon pools to polycyclic aromatic compounds, charcoal, and recalcitrant black carbon. Abundance and distribution of these carbon pools are affected by the severity of the wildfire, and the intensity and frequency of post-fire rainstorms. However, there is no comprehensive knowledge available about the impacts of both fire conditions and post-fire rainstorms on the fate of pyrogenic organic carbon (PyOC) and nitrogen (PyON) in burned terrestrial and aquatic ecosystems. To address the knowledge gap, we will collaborate with scientists at USDA Forest Service and Oak Ridge National Laboratory to conduct watershed-scale wildfire experiments in the Department of Energy - Savannah River Site, South Carolina. Production, composition, fluxes, and temporal dynamics of PyOC and PyON in both soil and surface runoff under different fire severity conditions as well as intensity and frequency of post-fire rainstorms will be determined under controlled field conditions. Leachability, degradability, and mobility of PyOC and PyON will be quantified in controlled conditions. Microbial communities will be assessed for resistance and resilience as well as function in relation to watershed perturbation and post-fire nutrient pools. Data obtained from the experiments will be used to develop, calibrate, and evaluate a reactive transport model of PyDOM and nutrients in burned landscapes. The results from field and laboratory experiments will be used to develop a reaction network accounting for dissolved and particulate black carbon and black nitrogen as well as production of C and N gases. The reaction network will be implemented in the PFLOTRAN software. Flow and transport of particulate and dissolved phases will be modeled with ATS, which uses the Alquimia interface to access PFLOTRAN’s reaction capability. Key parameters appearing in the flow and reactive transport model will be estimated by uncertainty-aware inverse modeling using the measured C and N fluxes. ATS-PFLOTRAN models of the plot and small watershed experiments will then be used to assess transferability of estimated parameters across scales.
Award Recipient(s)
  • USDA Forest Service (PI: Atkins, Jeffrey)
  • Clemson University (PI: Donald, Hagan)