Geological and Environmental Sciences Seminar

“Advancing understanding of soil hydraulic and biogeochemical dynamics across coastal interfaces using electrical signals” by Efemena Emmanuel, PhD. Student at UToledo
Coastal interfaces are areas where land and Lake water meet and are strongly affected by flooding, sea-level rise, and increasing salinity. These changes can alter soil moisture, water movement, organic matter, oxygen availability, and redox conditions. Understanding these changes is important because they affect how coastal ecosystems function, transform and respond to disturbance. However, coastal interfaces are highly heterogeneous, meaning that soil conditions can vary greatly over short distances and change over time. This makes their properties and responses difficult to measure and quantify. Therefore, this study focused on how electrical signals can describe and monitor changes in soil properties and redox conditions across coastal interfaces. This study was carried out at experimental sites in Lake Erie and Chesapeake Bay, Maryland, using field and controlled laboratory measurements to investigate how electrical signals can help describe changes in coastal soils. Electrical conductivity was used to examine how easily electrical current moves through soil and how water and salinity affect it. Electrical polarization (IP), which describes how soil stores electrical charge, was used to examine saturated hydraulic conductivity (Ks) and how organic matter content varies. Self-potential (SP), a naturally occurring electrical signal in the soil, was explored to monitor changes in redox conditions. IP results captured variation in Ks and organic matter content and were also affected by salinity. SP changed with redox potential, soil moisture, and flooding, with the SP–Eh relationship changing over time. In general, electrical signals provide a non-invasive approach for monitoring changes across coastal interfaces and improving understanding of their responses to flooding and salinity.

Biography
Efemena Emmanuel is a PhD student in Dr Doro’s Hydro- & Environmental Geophysics research group (UToledo HEG-Lab). His work supports geophysical research on forensic studies, wetland soil and hydrological characterization and monitoring, as well as the co-mentoring of undergraduate research students. Efemena holds a bachelor’s degree in Physics and a master’s degree in Geophysics, both from Delta State University, Nigeria. He earned a second master’s degree in Geology from the Department of Environmental Sciences at the University of Toledo in 2022 before commencing his doctoral studies in January 2023. Efemena is building a research career in environmental sciences, applying his quantitative skills to address the world’s growing environmental challenges. His research interests include developing high-resolution geophysical inverse solutions and simple field methods for hydrology and shallow subsurface imaging. His goal is to apply these techniques to contribute to the science-based management of complex terrain systems, predict highly variable groundwater flow and solute transport across diverse hydrological settings.