Application of Ground Penetrating Radar to Investigate Methane and Soil Carbon Dynamics at the Weyandt Environmental Monitoring Site in Western Pennsylvania

Recent studies involving methane budgets of western Pennsylvania have sought to quantify the amount and rate of fugitive methane released during industrial natural gas development and from distribution systems. However, in order to fully understand the carbon cycle and budget of the area, contributions from natural systems such as wetlands are also needed. Our research utilizes a combination of indirect non-invasive geophysical methods (ground penetrating radar, GPR), aerial imagery, and direct measurements (coring and gas traps) to estimate the contribution of wetlands to the total carbon stock of an agricultural and gas-producing site known as the Weyandt Farm Environmental Monitoring Site in Indiana, Pennsylvania.Our approach uses three-dimensional (3D) GPR surveys to define the thickness from the wetland surface to the regolith or bedrock interface in order to create a volume model of gas-producing organic soils. Depth-profile cores are extracted to confirm soil column interfaces and determine changes in soil carbon content with depth. In addition, gas traps placed across the wetlands measure the spatial and temporal variability of gas methane released. Carbon stocks across the monitoring site are estimated from aerial photographs and are used to determine surface area of each wetland type and develop a relationship between surface area and total carbon stocks within those wetlands. These values can be up scaled to estimate carbon stocks across similar landscapes within broader regions.This research demonstrates the ability of indirect geophysical methods to quickly estimate carbon stocks within irregular wetlands. This will be important when trying to understanding the environmental impact of methane released from both naturally occurring sources and commercial extraction and distribution activities.