Researchers develop predictive model measuring nitrous oxide emissions in streams and rivers

April 12, 2017 by Jennifer Tank
Researchers develop predictive model measuring nitrous oxide emissions in streams and rivers
Jennifer Tank. Credit: University of Notre Dame

When it comes to greenhouse gases, carbon dioxide tends to steal the spotlight—but new research in the journal Proceedings of the National Academy of Sciences (PNAS) reveals how scientists have developed a new, predictive tool to estimate nitrous oxide (N2O) emissions from rivers and streams around the world. N2O, a greenhouse gas with 300 times the warming potential of carbon dioxide, persists for over a century in the Earth's atmosphere and is known to cause significant damage to the Earth's ozone layer. Rivers and streams can be sources of N2O because they are hotspots for denitrification, a process whereby microbes convert dissolved nitrogen into nitrogenous gas.

While previous research has attempted to quantify where and when N2O is emitted, rivers and streams have posed a significant challenge because accurately measuring N2O from flowing waters is difficult, particularly at the scale of an entire river system. The current study presents a widely applicable predictive model from which to estimate N2O emissions from waterways based on simple metrics including stream size, land use and land cover of adjacent landscape, biome type and varying climatic conditions.

"Rapid land use change, such as the conversion of historic wetlands to agricultural lands, has increased the delivery of bioavailable nitrogen from the landscape to the detriment of receiving streams and rivers," said Jennifer Tank, Galla Professor in the Department of Biological Sciences at the University of Notre Dame, co-author of the study and director of Notre Dame's Environmental Change Initiative. "Some of that nitrogen will be converted by microbes into N2O, and because it is a powerful , where and when that happens in flowing waters is of great interest, both now and into the future."

Working with an international team of scientists, Tank and her graduate student Martha Dee analyzed previously published emissions data from streams and rivers around the world including Michigan's Kalamazoo River, New York's Hudson River, the Swale-Ouse River in the United Kingdom and six large rivers across Africa. In addition, the team collected its own measurements of N2O from two regionally, including the Manistee River in Michigan and the Tippecanoe River in Indiana. The researchers' analysis of the combined dataset found that N2O emissions are dependent on river size—as it increases, the production of N2O shifts from the streambed to the overlying water.

"The current understanding of production is limited in stream and river networks in a time of rapid global change," said Dee co-author of the study. "Our study uses a diverse, global set of data combined with regional measurements to create a model that that can better predict the impact of human activity and environmental drivers on N2O production."

The new model will be a valuable tool for scientists and water managers alike, as the framework allows for accurate prediction of N2O emissions under a variety of scenarios including water temperature, changes in land use and the influence of climate change on outcomes.

Explore further: Waterways contribute to growth of potent greenhouse gas

More information: Alessandra Marzadri et al. Role of surface and subsurface processes in scaling NO emissions along riverine networks, Proceedings of the National Academy of Sciences (2017). DOI: 10.1073/pnas.1617454114

Related Stories

Waterways contribute to growth of potent greenhouse gas

December 20, 2010

Nitrous oxide, a potent greenhouse gas, has increased by more than 20 percent over the last century, and nitrogen in waterways is fueling part of that growth, according to a Michigan State University study.

Recommended for you

Mountain glaciers shrinking across the West

October 22, 2017

Until recently, glaciers in the United States have been measured in two ways: placing stakes in the snow, as federal scientists have done each year since 1957 at South Cascade Glacier in Washington state; or tracking glacier ...

Carbon coating gives biochar its garden-greening power

October 20, 2017

For more than 100 years, biochar, a carbon-rich, charcoal-like substance made from oxygen-deprived plant or other organic matter, has both delighted and puzzled scientists. As a soil additive, biochar can store carbon and ...

Cool roofs have water saving benefits too

October 20, 2017

The energy and climate benefits of cool roofs have been well established: By reflecting rather than absorbing the sun's energy, light-colored roofs keep buildings, cities, and even the entire planet cooler. Now a new study ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.