2024 Abstracts

Constraining the Timing and Tempo of Clay Mineral Formation and Organic Matter Stabilization in an Alpine Watershed: East River, Colorado, United States


Evan Ramos1,2* ([email protected]), Mark Torres1, Daniel Ibarra2, Matthew Winnick3, Kenneth Williams4


1Rice University, Houston, TX; 2Brown University, Providence, RI; 3University of Massachusetts–Amherst, MA; 4Energy Geoscience Division, Lawrence Berkeley National Laboratory, Berkeley, CA


Soil organic carbon (OC) constitutes the largest terrestrial pool of carbon, and changes in its size have the potential to modulate atmospheric CO2 levels. As such, the underlying controls on OC stabilization and their sensitivities to climatic change have been increasingly scrutinized. The existing paradigm for OC stabilization suggests that due to their high specific surface areas and negatively charged surfaces, secondary clay minerals that form in soil protect OC from oxidation. Thus, a direct relationship between clay mineral abundance and OC may hold across soil types and climates. Despite this understanding, reactive transport models (RTMs) cannot reconcile soil geochemistry and OC profiles, pointing to knowledge gaps regarding organo-mineral interactions and their constitutive controls. Consequently, these challenges result in great uncertainty in the treatment of soil OC dynamics in Earth systems models and their concomitant effects on future climate projections. To further understand clay mineral formation and its relationship with OC dynamics over a hydrologic year, the team first interprets published river solute data from the East River Watershed, CO. Numerical couplings will help validate these preliminary findings.