The research was published in a recent issue of the journal Wetlands.
Often called the "kidneys" of the environment, wetlands act as buffer zones between land and waterways. They also act as sinks wetlands filter out chemicals in water that runs off from farm fields, roads, parking lots and other surfaces, and hold on to them for years.
The study examined methane fluxes over a two-year period during which researchers created two different kinds of conditions in two 2.5-acre experimental wetlands. In 2004, scientists used pumps to deliver monthly pulses to create conditions in the wetlands resembling natural marshes flooded with river water. In 2005, researchers pumped approximately the same amount of water but maintained a constant flow of water through the wetlands to mimic less dynamic hydrologic conditions. In addition to methane emissions, the study also investigated other processes such as denitrification, sedimentation, and aquatic productivity.
The pulsing hydrology experiment was maintained and methane levels were measured approximately twice monthly over the two study years by Mitsch, also an environment and natural resources professor at the Olentangy River Wetland Research Park, and study co-author Anne Altor, a former Ohio State graduate student who is now a consultant in Indianapolis. During both years, more methane was emitted during the summer than during other seasons in all portions of the wetlands, with emissions about four times higher during summer in the edge zones. Consistently wet areas released more gases in the spring than did edge zones under both conditions.
Methane is composed of carbon and hydrogen, and its emissions are expressed in terms of the amount of carbon released into the atmosphere. The emissions were at their highest during the summer of the steady-flow
|Contact: William Mitsch|
Ohio State University