Wright, William J.

Peat soils are known to be a significant emitter of atmospheric greenhouse gasses.
However, the spatial and temporal variability in production and release of greenhouse
gases (such as methane) in peat soils remains uncertain, particularly for low-latitude
peatlands like the Florida Everglades, as the majority of studies on gas dynamics in
peatlands focus on northern peatlands. The purpose of the work outlined here is focused
on understanding the spatial and temporal variability in biogenic gas dynamics (i.e.
production and release of methane and carbon dioxide) by implementing various
experiments in the Florida Everglades at different scales of measurement, using noninvasive
hydrogeophysical methods. Non-invasive methods include ground-penetrating
radar (GPR), gas traps, time-lapse cameras, and hydrostatic pressure head measurements,
that were constrained with direct measurements on soil cores like porosity, and gas
composition using gas chromatography. By utilizing the measurements of in-situ gas
volumes, we are able to estimate gas production using a mass balance approach, explore
spatial and temporal variabilities of gas dynamics, and better constrain gas ebullition models. A better understanding of the spatial and temporal variability in gas production
and release in peat soils from the Everglades has implications regarding the role of
subtropical wetlands in the global carbon cycle, and can help providing better production
and flux estimates to help global climate researchers improve their predictions and
models for climate change.

Peat soils are known to be a significant source of atmospheric greenhouse gasses. However, the releases of methane and carbon dioxide gasses from peat soils are currently not well understood, particularly since the timing of the releases are poorly constrained. Furthermore, most research work performed on peatlands has been focused on temperate to sub-arctic peatlands, while recent works have suggested that gas production rates from low-latitude peat soils are higher than those from colder climates. The purpose of the work proposed here is to introduce an autonomous Ground Penetrating Radar (GPR) method for investigating the timing of gas releases from peat soils at the lab scale utilizing samples originating from Maine and the Florida Everglades, and at the field scale in a Maine peatland. Geophysical data are supported by direct gas flux measurements using the flux chamber method enhanced by timelapse photography, and terrestrial LiDAR (TLS) monitoring surface deformation.