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Integrating Redox and Soil Geochemical Interactions with Carbon Cycling in a Land Surface Model

Presentation Date
Thursday, December 16, 2021 at 4:00pm
Convention Center - Poster Hall, D-F



Redox cycles, mineralogy, and pH are recognized as key drivers of soil carbon cycling, 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 dynamics are important. Integrating cycling of redox-sensitive elements such as iron, sulfur, and manganese could therefore allow models to better represent key elements of carbon cycling and greenhouse gas production. We describe a model framework that couples the Energy Exascale Earth System Model (E3SM) Land Model (ELM) with the geochemical reaction network model PFLOTRAN, allowing geochemical processes to be integrated with land surface model simulations. We implemented reaction networks including organic matter decomposition coupled to iron reduction, sulfate reduction, and manganese-dependent degradative enzymes as well as pH-dependent precipitation and dissolution of iron and manganese bearing minerals. We demonstrate the utility of this model framework with simulations of interactions between iron reduction and methanogenesis in permafrost soils, interactions between manganese and leaf litter decomposition in temperate forests, and interactions between salinity, sulfur, and vegetation productivity in coastal wetlands. Simulations including redox interactions yielded significantly different patterns of organic matter degradation and greenhouse gas production, showing how including more detailed chemical processes can improve model simulations of ecosystem processes in systems where redox cycling is important.

Funding Program Area(s)