Time-lapse geophysical measurements targeting spatial and temporal variability in biogenic gas distribution and releases from peat soils in a hydrologically controlled wetland in the Everglades

English Abstract:

Peat soils are known to release globally significant amounts of methane (CH₄) and carbon dioxide (CO₂) to the atmosphere. However, uncertainties still remain regarding the spatio-temporal distribution of gas accumulations and triggering mechanisms of gas releasing events. Furthermore, most peatland gas dynamics research has historically been focused on high latitude peatlands, while recent works have suggested that gas production rates from low-latitude peat soils may be higher than those from colder climates. Therefore, understanding gas dynamics in low-latitude peatlands (e.g. the Florida Everglades) is key to global climate research. Recent studies in the Everglades have demonstrated that biogenic gas flux values may vary when considering different temporal scales of measurements (i.e. hourly vs. daily averages). The work presented here mainly targets spatial variability in gas production and release at the plot scale in an approximately 85 m² area. The study was conducted during two separate field campaigns in the Loxahatchee Impoundment Landscape Assessment (LILA), a hydrologically controlled, landscape scale (30 Ha) model of the Florida Everglades. Ground penetrating radar (GPR) has been used in the past decade to non-invasively investigate the release of biogenic gases from peat soils. A grid of GPR profiles was collected to image biogenic gas distribution over the study area and estimate biogenic gas production and flux from its temporal variability. Also, gas flux chambers outfitted with time-lapse cameras captured high resolution gas flux measurements in order to constrain GPR data.