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261-3 Exploring the Impacts of Saltwater Intrusion into the Pore Structure of Freshwater Peat Soils using Laboratory Techniques

Session: The Current Understanding of the Role of Wetland Hydrology in the Cycling of Elements and other Substances: A Technical Session in Memory of Paul H. Glaser (Posters)

Poster Booth No.: 61

Presenting Author:

Imani Newton

Authors:

Newton, Imani¹, Islam, Md Rajeun², Nering, Danielle³, Adams, Sam⁴, Harkas, Emmanuel⁵, Knaub, Jamie⁶, Comas, Xavier⁷

(1) Department of Geosciences, Florida Atlantic University, Boca Raton, FL, USA, (2) Department of Geosciences, Florida Atlantic University, Boca Raton, FL, USA, (3) Department of Earth and Environment, Florida International University, Miami, FL, USA, (4) Department of Earth and Environment, Florida International University, Miami, FL, USA, (5) College Academy at Broward College, Davie, FL, USA, (6) FAU Lab Schools, Florida Atlantic University, Boca Raton, FL, USA, (7) Department of Earth and Environment, Florida International University, Miami, FL, USA,

Abstract:

Peat soils are important resources found worldwide that serve as carbon reservoirs and play a critical role in the water and biogeochemical cycles. While plant composition of peat soils varies with latitude, physical properties are similar and characterized by high porosity values that result in high water storage capacity, and play a role in the accumulation and release of biogenic gases like methane. Coastal peat soils are often affected by a shallow soil subsidence referred as peat collapse that while typically associated with saltwater intrusion, is not very well understood from a mechanistic standpoint. As an increase in saltwater intrusion in freshwater peat soils is expected in the coming years due to sea level rise and storm surges, it is becoming increasingly important to build an understanding of how saline intrusion affects the structural integrity of peat soils. Previous studies have shown that salinity increases in peat soils induce a pore dilation effect that may result in changes in physical properties, and that is potentially reversible. We hypothesize that repeated cycles of pore dilation in peat soils may play a role in the collapse of the peat matrix. In this study we tested two different peat soils from contrasting latitudes, subtropical peat soils from the Everglades and boreal soils from a peatland in Maine. Soils were saturated with progressively increasing salinity ranging from fresh to saltwater, and physical properties were measured using X-ray computed tomography (CT) scans and hydraulic conductivity (K) tests to monitor the changes in pore dilation over time. Preliminary results confirm that K increases with salinity in soils from the Everglades, and at rates consistent with changes shown from other studies in the Everglades. Furthermore, CT scanning images from Sphagnum samples confirm the increase in porosity with increased salinity, accounting for a 7% increase in porosity after a 72hour exposure to sea water conductivity (3.0 S/m). This work aims at exploring the existence of potential salinity thresholds, relevant to restoration efforts, that may induce changes in the structure of the peat matrix and define boundaries where such changes may become permanent and irreversible.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10864

Exploring the Impacts of Saltwater Intrusion into the Pore Structure of Freshwater Peat Soils using Laboratory Techniques

Description

Session Format: Poster

Presentation Date: 10/22/2025

Presentation Room: HBGCC, Hall 1

Poster Booth No.: 61

Author Availability: 9:00–11:00 a.m.

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