Wildfire significantly changes the composition and quantity of forest biomass, converting lignin and polysaccharide rich and relatively degradable carbon pools to polycyclic aromatic and charcoal rich and recalcitrant black carbon. Abundance and distribution of these carbon pools are affected by the severity of a wildfire, and the intensity and frequency of post-fire rainstorms. However, there is no comprehensive knowledge available about the impacts of both fires and post-fire rainstorms on the fates 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 severity of wildfires as well as intensity and frequency of post-fire rainstorms will be determined in the field conditions. Leachability, degradability, and mobility of PyOC and PyON will be quantified in controlled conditions. Microbial communities will also 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 BC and BN. To achieve the objectives of DOE-ESS funded project, we are requesting instrument time and support including FT-ICR-MS, NMR, nano-FTIR, and ICP-MS to determine the molecular structure and composition of samples collected from the wildfire experiments.