279-8 Large peat basins as reservoirs of methane and carbon dioxide: Evaluation of gas saturation

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

Presenting Author:

D Janecky

Authors:

Janecky, D R¹, Glaser, P H², Siegel, D I³, Chanton, J P⁴, Rosenberry, D O⁵, Reeve, A S⁶, Romanowicz, E A⁷, Chasar, L⁸, Corbett, L E⁹

(1) DRJ Geochemistry, Los Alamos, NM, USA, (2) Earth & Environmental Sciences, University of Minnesota, Minneapolis, MN, USA, (3) Earth Sciences, Syracuse University, Syracuse, NY, USA, (4) Department of Earth, Ocean & Atmospheric Science, Florida State University, Tallahassee, FL, USA, (5) U.S. Geological Survey, Lakewood, CO, USA, (6) School of Earth & Climate Sciences, The University of Maine, Orono, ME, USA, (7) Center for Earth & Environmental Science, CEES SUNY Plattsburgh, Plattsburgh, NY, USA, (8) Florida State University, Guilford, VT, USA, (9) Department of Earth, Ocean & Atmospheric Science, Florida State University, Tallahassee, FL, USA,

Abstract:

Peatlands are globally important sources for methane and carbon dioxide to the atmosphere. These two gases are believed to be important drivers for climate change over the past 800,000 years. However, release mechanisms and their quantification in peatlands as important reservoirs is complicated. We therefore analyzed our long (1990-2009) dataset of gas solutes from deep peat profiles with respect to chemical thermodynamic data and model simulations.

Our field data was collected from deep (up to 4 m) pore-water profiles across a 720,000-ha study area within the Glacial Lake Agassiz Peatlands of Minnesota. This study area is distinguished by its (a) immense size and relatively undisturbed nature, (b) diverse array of patterned bogs and fens, and (c) extensive peat cover. Visual observations confirmed that bubbles were abundant in the deep peat during synoptic pore-water sampling campaigns in 1990-1991, 1997-1998, and 2008-2009. This evidence is supported by geophysical evidence that also detected changes due to apparent recurring ebullition events. We compare the field datasets for time and depth series of dissolved gas compositions at each individual site to the calculated solubility of three component mixtures (CH₄, CO₂, N₂) from chemical thermodynamic data.  Using these solubility trends, initial calculations of bubble release and ebullition trends have been developed.

Our simulations indicate that measured methane concentrations are near saturation with respect to mixed-composition gas bubble formation in these peatland pore waters. Therefore, these sites are either poised for ebullition or actively undergoing ebullition, resulting in a substantial active inventory of CH₄.  Variations between sites in space and time present opportunities for further research that Dr. Paul Glaser was very interested in encouraging.

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

doi: 10.1130/abs/2025AM-9818

© Copyright 2025 The Geological Society of America (GSA), all rights reserved.