EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Carbon delivery to floodplain aquifers in response to water table fluctuations: Observations from soil column experiments

Maria Scaccia1, Rachel Gabor3, Fabian Wilbert2, Christian Roumelis1, Susana Bernal5, Susan Welch1, Jesús Carrera Ramirez4,6, Albert Folch5,6, Miquel Salgot5, Alycia Insalaco7, and Audrey H. Sawyer1
Maria Scaccia et al.
  • 1School of Earth Sciences, The Ohio State University, Columbus, Ohio USA
  • 2Department of Geology, University of Vienna, Vienna, Austria
  • 3School of Environment and Natural Resources, The Ohio State University, Columbus, Ohio USA
  • 4Institute of Environmental Assessment and Research, Barcelona, Spain
  • 5Associated Unit: Hydrogeology group (UPC-CSIC)
  • 6School of Civil and Environmental Engineering, Universitat Politécnica de Catalunya, Barcelona, Spain
  • 7National School for Water and Environmental Engineering, University of Strasbourg, Strasbourg, France

Water tables in floodplain aquifers rise and fall over a variety of timescales in response to changes in recharge, discharge, floods, and water use. To investigate the effects of water table fluctuations on DOC delivery to groundwater, an experiment was conducted at two Mediterranean sites: a pristine forested stream and an urban coastal floodplain. Groundwater was pumped into and out of the bottom of the soil column at varying rates to simulate water table fluctuations over a period of 16 days. Flooding events were imitated by inundating the top of the column with water sourced from nearby surface water features. The effects of repeated wetting and drying events on carbon mobilization, DOM quality, and geochemical responses were measured. Preliminary analysis reveals strong downward movement of DOC from soil layers after wetting events. SUVA at 254 nm increased with DOC concentrations compounds within pore waters during wetting events. During initial water table fluctuations, redox potential near the soil-aquifer interface was relatively stable but declined after subsequent wettings. Forthcoming analyses will also examine changes in the humification, fluorescence, and freshness indices of DOM from excitation-emission matrices. This study shows the influence of multiple saturation events on carbon mobilization and shallow groundwater biogeochemistry in unique floodplains.

How to cite: Scaccia, M., Gabor, R., Wilbert, F., Roumelis, C., Bernal, S., Welch, S., Carrera Ramirez, J., Folch, A., Salgot, M., Insalaco, A., and H. Sawyer, A.: Carbon delivery to floodplain aquifers in response to water table fluctuations: Observations from soil column experiments, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-16927,, 2023.