Dissolved Organic Matter Sources from Soil Horizons with Varying Hydrology and Distance from Wetland Edge

Abstract:

Understanding hydrologic controls on carbon accumulation and export within geographically isolated wetlands (GIW) has implications for the success of wetland restoration efforts intended to produce carbon sinks. However, little is known about how water storage and flows in GIW catchments influence carbon dynamics, particularly regarding dissolved organic matter (DOM) transport and transformation. Soils within and adjacent to wetlands are sources of DOM dependent on variable moisture and redox conditions. To understand the role of different soil horizons as sources of DOM, an extractable DOM experiment was performed on soil horizon samples collected from upland to wetland transects at multiple GIWs on the Delmarva peninsula within the eastern United States. Extractable DOM was analyzed for DOM concentration and composition. Preliminary results suggest that extractable DOM concentration is highest in organic soil horizons of all transect points and that upland organic horizons have higher extractable DOM concentrations than wetland organic horizons. Relating DOM concentration and composition to frequency of inundation and redox status will inform which soil horizons are most biogeochemically significant for subsurface DOM transport in Delmarva and other GIW systems.