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Pore-scale evidence of tidal wetland soil carbon stabilization

EMSL Project ID


The high capacity of vegetated coastal ecosystems to preserve organic carbon is well documented but remains poorly understood at a mechanistic level, challenging emerging efforts to account for carbon dynamics at the terrestrial-aquatic interface. Several important explanatory mechanisms for carbon preservation have been supported by empirical data and numerical models, but further progress requires integration across disciplines. This pilot study coupling physical, ecological and chemical observations spatially, within neighboring but geomorphically distinct tidal marsh soils, can be used to prioritize sampling for landscape model development. We propose that coupling the concepts of chemical transport limitation and plant-hydrology-geomorphic feedbacks yields a unified conceptual framework and testable hypotheses for future observations and models of carbon preservation in vegetated coastal wetlands. Preservation is favored by processes that separate organic electron donors from high free energy-yielding electron acceptors, particularly molecular oxygen. The physical principles in Darcy’s law therefore predict that carbon stabilization is favored by rapid burial, increasing distance from a tidal channel, and low soil permeability. Reactive transport studies and models capture these fundamental limitations on organic carbon degradation rates, but not the important feedbacks between plant production, inundation frequency, and soil properties that alter the biogeochemistry and hydrodynamics of reactive transport. Our fluid transport-centric conceptual model of carbon preservation calls for explicit studies and models that integrate the physical, chemical, hydrologic, geomorphic and ecological mechanisms that link wetland soil development to rates of carbon stabilization. EMSL observational and modeling capabilities provide an opportunity to test initial hypotheses of the relative role of fluid transport in spatial and historic patterns of soil carbon accumulation and stabilization in intertidal soils, as well as other saturated soils and sediments across the land-ocean aquatic continuum.

Project Details

Project type
Exploratory Research
Start Date
End Date


Principal Investigator

Lisamarie Windham-Myers
U.S. Geological Survey