Yet much remains unknown about how much gas is actually released from these water systems and the chemical and ecological dynamics that affect their transport.
A new Yale study reveals important insights into the factors that influence the release of greenhouse gases from these inland waters, including a key relationship between storm events, ecology, and topography in moderating this release.
In an analysis of headwater streams in central Connecticut, scientists found that concentrations of three greenhouse gases — carbon dioxide, nitrous oxide, and methane — increased in wetland streams during rainstorms, but decreased or remained constant in forested streams. However, those gases were also less likely to be released
from the wetland streams than from the streams in forested areas, they found.
Writing in the Journal of Geophysical Research: Biogeosciences
, they conclude that these variances are likely due to the fact that forested streams tend to be steeper, creating greater turbulence that, in turn, promotes gas releases. Meanwhile, in wetland streams those inputs were more likely to be carried downstream farther from their source, said Kelly Aho
, a doctoral candidate at the Yale School of Forestry & Environmental Studies (F&ES) and lead author of the study.
“When you think about what a wetland looks like, it makes sense: wetlands are really flat, which is why water and organic matter may accumulate there,” Aho said. “As a result, during a rainstorm those wetlands and their soils are a source of greenhouse gases.”
“But,” she added, “gas concentrations represent only half the equation.”