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

Wildfire significantly changes the composition and quantity of forest biomass,

biomass

Material that comes from living things, including trees, crops, grasses, and animals and animal waste. Some kinds of biomass, such as wood and biofuels, can be burned to produce energy.

Source: EPA Global Climate Change Source

converting lignin

lignin

One of the main components of plant cell wall and it is a natural phenolic polymer with high molecular weight, complex composition and structure.

Source: NIH Source

and polysaccharide rich and relatively degradable carbon pools to polycyclic aromatic compounds, charcoal, and recalcitrant black carbon.

black carbon

The sooty black material emitted from gas and diesel engines, coal-fired power plants, and other sources that burn fossil fuel. It comprises a significant portion of particulate matter or PM, which is an air pollutant.

Source: EPA Source

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

nitrogen

Classified as a nonmetal, nitrogen is a gas at room temperature. Nitrogen dilutes oxygen and prevents rapid burning at the Earth's surface, and accounts for ~78 percent of Earth's atmosphere.

Source: National Library of Medicine Source

(PyON) in burned terrestrial

terrestrial

The geographical and biological features that are associated with the Earth's solid, rocky surface, residing on or resembling the land or terrain found on our planet.

Source: NASA Source

and aquatic ecosystems.

ecosystem

A natural community of plants, animals, and other living organisms and the physical environment in which they live and interact.

Source: A student's guide to Global Climate Change Source

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,

flux

The amount of some type of particle or energy crossing a unit area per unit time.

Source: NRC Library Source

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

watershed

An area of land that channels rainfall and snowmelt to creeks, streams, and rivers, and eventually flows to the lowest point in a basin.

Source: USGS Source

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.