The interplay between the terrestrial carbon cycle and carbon dioxide emissions from streams and rivers into the atmosphere is the focus of a new study led by the Yale School of the Environment to calculate the amount of the global budget for carbon emissions.
The study by a team of researchers co-authored by YSE Professor of Ecosystem Ecology Peter Raymond and published in PNAS compiled 5,910 direct measurements of fluvial CO2. Globally, the magnitude of CO in streams and rivers2 emissions are affected by seasonal changes, biogeochemistry and watershed hydrology. Global flux estimates were uncertain. Co-authors include Shaoda Liu, postdoctoral associate at YSE; Catherine Kuhn, Kelly Aho, David Butman, Ph.D. and postdoctoral researcher; and researcher Guiseppe Amatulli.
“This study demonstrates that there is more CO2 flowing out of streams and rivers into places where landscapes are fixing more carbon,” says Raymond. “This allows us to better understand the important links in the global carbon budget between terrestrial and aquatic ecosystems.
The study builds on Raymond’s research published in 2013 which developed the world’s first map of the surface of water bodies and their carbon emissions. But in 2013, there were no direct on-site measurements, and calculations were based on alkalinity and pH and other data, Raymond says.
“We’re starting to ease the uncertainty,” he says. “And that’s proof that people on the ground are taking action now.”
The study found that monthly emission fluxes vary more in arctic and north temperate rivers than in tropical and south temperate rivers.
His findings underscore the importance of hydrology in the role of water in transporting terrestrial carbon to the atmosphere via global drainage networks.
“The amount of carbon moved and respired by Earth’s rivers affects the balance between Earth’s terrestrial biosphere, the ocean and the atmosphere. Our work highlights the importance of terrestrial hydrology in determining where and when rivers move a large amount of carbon from the terrestrial biosphere into the atmosphere,” says Liu, who is also an assistant professor at Beijing Normal University.
The amount of terrestrial CO2 which is eliminated in streams and rivers and then emitted into the atmosphere, is modulated by the flow of rivers, according to the study.
“We are really interested in this connectivity, and we would like to understand how variability and hydrology create differences in this connectivity. This becomes important for the chemistry of streams and rivers in particular,” he says.
Climate change and human impact will also play a role in the terrestrial carbon cycle and emissions from streams and rivers as some areas dry out and others become wetter.
“An area of future research will determine the anthropogenic component of this flux. It is currently unknown,” Raymond said.
Streams and rivers emit more carbon dioxide at night than during the day
Shaoda Liu et al, The importance of hydrology in transporting terrestrial carbon to the atmosphere via the world’s streams and rivers, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2106322119
Provided by Yale University
Quote: New study aims to calculate role of terrestrial carbon in river and stream emissions (March 15, 2022) Retrieved March 15, 2022 from https://phys.org/news/2022-03-aims- terrestrial-carbon-role-river.html
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