Investigating Redox Dynamics in Coastal Wetlands: Integrating Biogeochemical and Electrochemical Approaches at Old Woman Creek
Authors
Timothy H. Morin1* (thmorin@esf.edu), Lauren E. Kinsman-Costello2, Chelsea Monty-Bromer3, John M. Senko4, Gil Bohrer5, Erin Hassett1, Erin Eberhard2, Thomas Quick4, Terry Heard4, Chelsea Smith2, Michael Back2, Bukola Adesanmi3, Talia Pope2
Institutions
1College of Environmental Science and Forestry, State University of New York–Syracuse, NY; 2Kent State University, Kent, OH; 3Cleveland State University, Cleveland OH; 4University of Akron, Akron, OH; 5The Ohio State University, Columbus, OH
Abstract
Redox processes in wetland environments, particularly in coastal systems like Old Woman Creek, OH, often deviate from predictions based on the traditional thermodynamic redox tower paradigm. This discrepancy is especially notable under transient hydrodynamic conditions. While redox potential (Eh) measurements provide insights, it inadequately captures the dynamic nature of microbial communities, which are central to these processes through a diverse array of catabolic reactions. To address this gap, researchers have integrated traditional biogeochemical indicators with innovative electrochemical methods, specifically zero resistance ammetry (ZRA). This study aims to (1) correlate dynamic hydrology in a freshwater terrestrial-aquatic interface wetland with redox regimes; (2) explore how redox heterogeneity influences elemental cycling at various scales; and (3) assess the effectiveness of microbial functional type representations in process-based models for capturing terminal electron acceptor stress. Researchers deployed ZRA sensors in the wetland sediment at Old Woman Creek during the summers of 2022 and 2023, alongside measurements of subsurface biogeochemical species concentrations, stratified redox sensors, and surface flux assessments. A batch reactor experiment was also conducted in 2023 for controlled observation of these processes. Preliminary findings from ZRA readings indicate significant variations correlating with water level changes and redox chemistry. These observations suggest a complex interplay between hydrology and redox dynamics, mediated by microbial activity.
Ongoing research involves aligning these findings with the process-based model ecosys. The team’s goal is to evaluate the model’s ability to replicate observed dynamics, particularly in representing dynamic microbial functional types and their metabolic reactions. This includes in silica experimental manipulation of water levels to simulate varying environmental conditions and demonstrating the dynamic microbial terminal electron stress expressed by the consortium of microbial communities.