Investigating the Potential of Airborne Ground-Penetrating Radar (GPR) to Identify Hot Spots for Biogenic Gas Accumulation and Release in Peat Soils from the Everglades
Md Rajeun Islam* (email@example.com), Umida Turamuratova, Shelley Peirce, Xavier Comas
Department of Geosciences, Florida Atlantic University–Boca Raton, FL
Subtropical peatlands play a vital role in the global carbon budget by generating fluxes of biogenic gases mainly composed of methane and carbon dioxide. Previous studies during the last 2 decades have advanced understanding on how to predict these carbon fluxes at a variety of spatial and temporal scales in peat soils; however, the spatial variability of gas accumulation (i.e., hot spots) at the matrix level is still unclear, mostly due to the difficulties of noninvasively imaging these areas. While most studies have traditionally relied on point measurements (i.e., flux chambers) or methods like eddy covariance with large footprints that may lack the resolution to properly capture hot spots for gas accumulation and release, several studies have shown the potential of ground-penetrating radar (GPR) to noninvasively image gas distribution at the matrix scale. However, the method still relies on ground-based measurements that are time consuming and limited in coverage. In this study, researchers tested the potential of airborne GPR measurements to efficiently characterize gas distribution in peat soils and identify the presence of hot spots at the laboratory scale. This study represents a first step before deploying field-based GPR measurements from a small unoccupied aircraft system (sUAS). A high-frequency antenna was suspended over a large peat monolith (0.75 m x 0.31 m x 0.25 m, extracted from the Loxahatchee Impounded Landscape Assessment in Water Conservation Area 1, FL, using a custom-made rail system that allowed for the antenna to move autonomously and monitor changes in dielectric permittivity associated with biogenic gas build up and release at high temporal resolution. Airborne GPR measurements were combined with transmission GPR, gas traps with time-lapse cameras (to infer gas fluxes), and gas chromatography (to analyze gas composition). Preliminary results show the potential of airborne GPR measurements to isolate hot spots for gas accumulation in peat soils at the laboratory scale and thus show promise for the use of sUAS at the field scale to characterize hot spots more efficiently for gas accumulation and release in the Everglades.