Examining the Effects of Elevated Atmospheric CO2 and Warming on Soil Redox Potential in a Maryland, USA Tidal Wetland

Tidal wetlands are important ecosystems, protectors of coastal infrastructure, and global carbon sinks. Understanding how these systems will respond to climate change is essential for scientists across a broad range of disciplines and has implications for policy makers and coastal populations. The Smithsonian Environmental Research Center in Edgewater, MD currently hosts a number of experiments in a tidal wetland that simulate conditions in a world experiencing warming and/or elevated atmospheric CO2 (eCO2). This research presents redox potential (Eh) data collected from 6 experimental marsh plots in the summer of 2019. Results indicate that the combined global change factors of warming and eCO2 will lead to more oxidizing soil environments in anoxic brackish tidal marshes due to increased availability of oxygen for use in methanotrophy. Further, there is a positive relationship between redox potential and water level at this field site - a finding contrary to other published studies of water level-Eh relationships in natural and simulated wetlands. There is no evidence of seasonal trends in redox potential at this site, though longer and more robust studies are needed to confirm this. Finally, no clear tidal signal exists for the site water level data, perhaps pointing to the importance of site-specific ground/surface water inputs and/or local weather patterns for site hydrology. Future work should expand on this study using advanced statistical analyses, including but not limited to mixed-effects models, autoregressive models, and more robust data collection