Sedimentation Evolution of Dredged Estuary
Location
CELA & Mary Church Terrell Library, First Floor
Document Type
Poster - Oberlin Community Only
Start Date
4-25-2025 12:00 PM
End Date
4-25-2025 2:00 PM
Research Program
Berkeley Geochronology Program, Rick and Robin Black Fund, Oberlin College RA fund, Mink Meadows Association Environmental Committee
Abstract
Estuarine sediment infilling is an emerging area of study due to sea-level rise; managed retreat and wetland restoration offer human-supported solutions. The Mink Meadows “Yacht Basin” on Martha’s Vineyard, created by dredging in 1963, provides an unlikely case study for the evolution of a human-constructed wetland over time. Sediment core samples of the basin and surrounding marshes were measured for fallout radionuclides 137Cs and excess 210Pb (210Pbex) to determine approximate amount and rate of sediment accumulation. Preliminary 210Pbex values and core analysis indicate quick initial sedimentation after dredging, followed by a steep decline in accumulation. Though near-constant 210Pbex concentrations in two lagoon cores suggest accelerating sedimentation rates, rates are not fast enough to fill significant portions of the lagoon before 2050; accounting for sea-level rise pushes the infill date estimate later. Approximately 40-48 cm of sediment have accumulated since dredging. Marsh cores are currently being analyzed for rate of sedimentation using 210Pbex concentrations to determine whether the surrounding marshes are a source of accumulating sediment. Tidal data will constrain saline-mobile 137Cs for more-precise dating. Moderately high LOI drops off sharply at the backhoe facies, suggesting heavily organic initial sediment followed by limited organic material. LOI core analysis is ongoing. Due to fluctuating LOI data, sediment source remains a question; SEM/XRD analyses will help further determine sediment composition. Current data show leveling similar to non-anthropogenic estuaries, suggesting successful geomorphologic stabilization. Evaluating the success and evolution of this constructed wetland will allow for better understanding of future wetland remediation efforts.
Keywords:
Wetlands, Geomorphology, Radioisotope dating
Recommended Citation
Duff, Teaghan, "Sedimentation Evolution of Dredged Estuary" (2025). Research Symposium. 18.
https://digitalcommons.oberlin.edu/researchsymp/2025/posters/18
Major
Geology
Environmental Studies
Project Mentor(s)
Amanda Schmidt, Geosciences
2025
Sedimentation Evolution of Dredged Estuary
CELA & Mary Church Terrell Library, First Floor
Estuarine sediment infilling is an emerging area of study due to sea-level rise; managed retreat and wetland restoration offer human-supported solutions. The Mink Meadows “Yacht Basin” on Martha’s Vineyard, created by dredging in 1963, provides an unlikely case study for the evolution of a human-constructed wetland over time. Sediment core samples of the basin and surrounding marshes were measured for fallout radionuclides 137Cs and excess 210Pb (210Pbex) to determine approximate amount and rate of sediment accumulation. Preliminary 210Pbex values and core analysis indicate quick initial sedimentation after dredging, followed by a steep decline in accumulation. Though near-constant 210Pbex concentrations in two lagoon cores suggest accelerating sedimentation rates, rates are not fast enough to fill significant portions of the lagoon before 2050; accounting for sea-level rise pushes the infill date estimate later. Approximately 40-48 cm of sediment have accumulated since dredging. Marsh cores are currently being analyzed for rate of sedimentation using 210Pbex concentrations to determine whether the surrounding marshes are a source of accumulating sediment. Tidal data will constrain saline-mobile 137Cs for more-precise dating. Moderately high LOI drops off sharply at the backhoe facies, suggesting heavily organic initial sediment followed by limited organic material. LOI core analysis is ongoing. Due to fluctuating LOI data, sediment source remains a question; SEM/XRD analyses will help further determine sediment composition. Current data show leveling similar to non-anthropogenic estuaries, suggesting successful geomorphologic stabilization. Evaluating the success and evolution of this constructed wetland will allow for better understanding of future wetland remediation efforts.
