2024 Abstracts

Simulating Arctic Soil Redox and Biogeochemical Interactions in the E3SM Land Model


Benjamin N. Sulman1* (sulmanbn@ornl.gov), Fengming Yuan1, Neslihan Taş2, Bailey Murphy1, Sean Fettrow1, Elizabeth Herndon1, David Graham1, Peter Thornton1, Colleen Iversen1


1Oak Ridge National Laboratory, Oak Ridge, TN; 2Lawrence Berkeley National Laboratory, Berkeley, CA



Redox cycles, geochemistry, and pH are recognized as key drivers of subsurface biogeochemical cycling in terrestrial and wetland ecosystems but are typically not included in terrestrial carbon cycle models. These omissions may introduce errors when simulating carbon cycling and greenhouse gas emissions in systems where redox interactions and pH fluctuations are important, such as wetland-rich tundra landscapes where saturated soil conditions combined with high soil iron concentrations can influence biogeochemistry. The project coupled the E3SM Land Model (ELM) with geochemical reaction network simulator PFLOTRAN, allowing geochemical processes and redox interactions to be integrated with land surface model simulations. Researchers implemented a reaction network including aerobic decomposition, fermentation, iron oxide reductive dissolution and dissolved iron oxidation, and methanogenesis as well as pH dynamics. The team used the model framework to simulate biogeochemical cycling and methane production across tundra landforms including permafrost polygons and thermokarst features. Model simulations were parameterized using laboratory incubations and compared well with measured porewater concentrations and surface gas emissions from Next-Generation Ecosystem Experiments Arctic field sites. These results demonstrate how directly simulating biogeochemical reaction networks can improve land surface model simulations of subsurface biogeochemistry and carbon cycling in tundra ecosystems.