Ebullition events monitored from northern peatlands using electrical imaging

Within northern peatlands, ebullition is potentially an important mechanism for the transport of methane (CH4) to the atmosphere. We applied electrical imaging to characterize the buildup and ebullition of biogenic gas bubbles in a spatially explicit manner. Ebullition events were monitored from a range of different peat types, with and without a vascular plant cover, under different meteorological conditions. Weekly changes in bulk electrical conductivity (sigma) were analyzed, during which variations in pore water conductivity had only a small effect on sigma. Bulk ebullition losses from the peat cores were independently measured using Mariotte regulators. The largest ebullition events were found to be spatially diffuse: the gas was released from a large volume of peat. We used a measure of the roughness of the electrical images to characterize the magnitude of gas bubble movement within each peat core. Our results show that small variations in air temperatures of 3 degrees C and variations in peat type between different microhabitats have a statistically significant influence on gas bubble dynamics.