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Imaging the Distribution of Hot Spots for Biogenic Gas in Peat From the Everglades Using Air‐Coupled Ground‐Penetrating Radar (GPR) at the Laboratory Scale.

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Title: Imaging the Distribution of Hot Spots for Biogenic Gas in Peat From the Everglades Using Air‐Coupled Ground‐Penetrating Radar (GPR) at the Laboratory Scale.
Authors: Islam, Md Rajeun1 (AUTHOR) mdrajeunisla2021@fau.edu, Comas, Xavier2 (AUTHOR)
Source: Journal of Geophysical Research. Biogeosciences. May2026, Vol. 131 Issue 5, p1-17. 17p.
Subject Terms: *Peatlands, *Carbon cycle, *Peat bogs, *Greenhouse gas mitigation, Ground penetrating radar, Methanotrophs, Remote sensing
Geographic Terms: Everglades (Fla.)
Abstract: Peatlands influence the global carbon cycle by storing carbon and releasing greenhouse gases such as methane (CH4) and carbon dioxide (CO2). Imaging hot spots for gas accumulation in peat remains challenging due to spatial and temporal heterogeneity and the invasive nature of traditional techniques. Minimally invasive geophysical methods such as ground‐penetrating radar (GPR) have been used to image gas distribution in peat, but the need for direct ground contact limits its applicability in isolated environments. To address these issues, this study evaluated the feasibility of laboratory‐based air‐coupled GPR, in which the antenna is suspended above the surface, to image hot spots for biogenic gas accumulation in peat. Air‐coupled and ground‐based GPR measurements were applied to a peat monolith (0.75 × 0.31 × 0.25 m) from the Everglades (FL, USA) and constrained by flux measurements from gas traps fitted with time‐lapse cameras and analyzed via gas chromatography. Air‐coupled GPR imaged hot spots for gas accumulation with lateral dimensions of 0.05 × 0.03 m to 0.15 × 0.20 m, with gas content up to 25%, fluxes up to 171.9 mg CH4 m−2 day−1, and CH4 contents exceeding 70%. Hot spots were associated with slightly higher porosity and distinct peat structure, suggesting that physical properties of peat may influence gas storage and release behavior. These results highlight the role of peat physical properties in CH4 emissions, demonstrate the potential of air‐coupled GPR for non‐invasive monitoring of biogenic gas dynamics under controlled conditions, and support future evaluation of drone‐based GPR surveys in peatlands. Plain Language Summary: Wetland soils are rich in organic matter and microorganisms that produce methane and carbon dioxide gases that contribute to the greenhouse effect when released into the atmosphere. Understanding how these gases are produced, stored, and released from peat is important for improving climate predictions. Traditional measurement methods often disturb the soil and gas systems when instruments are inserted directly into the ground. In this study, we tested a geophysical tool called ground‐penetrating radar (GPR) in a controlled laboratory experiment using a peat monolith collected from the Florida Everglades. The antenna was suspended above the soil surface, allowing non‐invasive measurements of gas distribution over space and time. These measurements were combined with direct gas collection and laboratory analysis to evaluate the ability of the method to detect localized gas accumulation. Results showed that gas content varied strongly across short distances and over time. Localized hot spots reached gas contents up to 25%, with methane fluxes up to 171.9 mg CH4 m−2 day−1 that were associated with slight differences in peat structure and porosity. The findings demonstrate the feasibility of air‐coupled GPR for detecting gas accumulation patterns under controlled conditions and support future field applications via drone measurements. Key Points: Air‐coupled ground‐penetrating radar (GPR) images hot spots for elevated biogenic gas accumulation and release in peat at the laboratory scaleHot spots of gas production, accumulation, and release in Everglades peat align with distinct porosity and peat structureAir‐coupled GPR shows feasibility for detecting gas hot spots, supporting future drone‐based surveys [ABSTRACT FROM AUTHOR]
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Description
Abstract:Peatlands influence the global carbon cycle by storing carbon and releasing greenhouse gases such as methane (CH4) and carbon dioxide (CO2). Imaging hot spots for gas accumulation in peat remains challenging due to spatial and temporal heterogeneity and the invasive nature of traditional techniques. Minimally invasive geophysical methods such as ground‐penetrating radar (GPR) have been used to image gas distribution in peat, but the need for direct ground contact limits its applicability in isolated environments. To address these issues, this study evaluated the feasibility of laboratory‐based air‐coupled GPR, in which the antenna is suspended above the surface, to image hot spots for biogenic gas accumulation in peat. Air‐coupled and ground‐based GPR measurements were applied to a peat monolith (0.75 × 0.31 × 0.25 m) from the Everglades (FL, USA) and constrained by flux measurements from gas traps fitted with time‐lapse cameras and analyzed via gas chromatography. Air‐coupled GPR imaged hot spots for gas accumulation with lateral dimensions of 0.05 × 0.03 m to 0.15 × 0.20 m, with gas content up to 25%, fluxes up to 171.9 mg CH4 m−2 day−1, and CH4 contents exceeding 70%. Hot spots were associated with slightly higher porosity and distinct peat structure, suggesting that physical properties of peat may influence gas storage and release behavior. These results highlight the role of peat physical properties in CH4 emissions, demonstrate the potential of air‐coupled GPR for non‐invasive monitoring of biogenic gas dynamics under controlled conditions, and support future evaluation of drone‐based GPR surveys in peatlands. Plain Language Summary: Wetland soils are rich in organic matter and microorganisms that produce methane and carbon dioxide gases that contribute to the greenhouse effect when released into the atmosphere. Understanding how these gases are produced, stored, and released from peat is important for improving climate predictions. Traditional measurement methods often disturb the soil and gas systems when instruments are inserted directly into the ground. In this study, we tested a geophysical tool called ground‐penetrating radar (GPR) in a controlled laboratory experiment using a peat monolith collected from the Florida Everglades. The antenna was suspended above the soil surface, allowing non‐invasive measurements of gas distribution over space and time. These measurements were combined with direct gas collection and laboratory analysis to evaluate the ability of the method to detect localized gas accumulation. Results showed that gas content varied strongly across short distances and over time. Localized hot spots reached gas contents up to 25%, with methane fluxes up to 171.9 mg CH4 m−2 day−1 that were associated with slight differences in peat structure and porosity. The findings demonstrate the feasibility of air‐coupled GPR for detecting gas accumulation patterns under controlled conditions and support future field applications via drone measurements. Key Points: Air‐coupled ground‐penetrating radar (GPR) images hot spots for elevated biogenic gas accumulation and release in peat at the laboratory scaleHot spots of gas production, accumulation, and release in Everglades peat align with distinct porosity and peat structureAir‐coupled GPR shows feasibility for detecting gas hot spots, supporting future drone‐based surveys [ABSTRACT FROM AUTHOR]
ISSN:21698953
DOI:10.1029/2025JG009504