Rivers are carbon processors, not inert pipelines

December 1, 2008

Microorganisms in rivers and streams play a crucial role in the global carbon cycle that has not previously been considered. Freshwater ecologist Dr. Tom Battin, of the University of Vienna, told a COST ESF Frontiers of Science conference in October that our understanding of how rivers and streams deal with organic carbon has changed radically.

Microorganisms such as bacteria and single celled algae in rivers and streams decompose organic matter as it flows downstream. They convert the carbon it contains into carbon dioxide, which is then released to the atmosphere.

Recent estimates by Battin's team and others conclude there is a net flux, or outgassing, of carbon dioxide from the world's rivers and streams to the atmosphere of at least two-thirds to three-quarters of a gigatonne (Gt) of carbon per year. This flux has not been taken into account in the models of the global carbon cycle used to predict climate change.

"Surface water drainage networks perfuse and integrate the landscape, across the whole planet," says Battin, "but they are missing from all global carbon cycling, even from the IPCC (Intergovernmental Panel on Climate Change) reports. Rivers are just considered as inert pipelines, receiving organic carbon from Earth and transporting it to the ocean." This thinking, according to Battin, has changed radically in last few years.

He argues that the latest estimates of how much carbon is transferred to the atmosphere from rivers and streams are very conservative. "The actual outgassing of carbon dioxide is probably closer to 2 Gt of carbon per year," says Battin. "Our surface area estimates only consider larger streams and rivers, because it is very hard to estimate accurately the surface area of small streams. So small streams are excluded, although in terms of microbial activity, they are the most reactive in the network."

Two gigatonnes of carbon per year is close to half the estimated net primary production of the world's vegetation each year. Realising that this quantity of carbon may be delivered straight back to the atmosphere, rather than being taken to the ocean where some of it is removed by marine organisms and ends up in sediment, could have profound consequences for our understanding of the system.

In a disturbing development, Battin's team lab has recently found that engineered nanoparticles can significantly compromise the freshwater microbes involved in carbon cycling. "This finding is a real challenge to science," says Battin. "Engineered nanoparticles such as titanium dioxide are expected to increase in the environment, but it remains completely unknown how they might affect the functioning of ecosystems."

Source: European Science Foundation

Explore further: Sunlight and the right microbes convert Arctic carbon into carbon dioxide

Related Stories

Six climate change solutions we can all agree on

September 22, 2017

In the U.S., few issues seem to be as divisive as climate change. Although the science is unequivocal, political polarization has taken climate change hostage. Fortunately, there are solutions that people on both sides of ...

Curbing climate change—why it's so hard to act in time

August 18, 2017

This summer I worked on the Greenland ice sheet, part of a scientific experiment to study surface melting and its contribution to Greenland's accelerating ice losses. By virtue of its size, elevation and currently frozen ...

Recommended for you

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 ...

5 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

GrayMouser
3 / 5 (4) Dec 01, 2008
Sounds like someone is fishing for grants. Especially considering that the paper's title is "Freshwater ecosystem research in the anthropocene: an imperative!"
Nartoon
3 / 5 (6) Dec 01, 2008
On the other hand, this new source of 2 Gt of CO2 is not man made, but purely natural.
Excalibur
1.3 / 5 (3) Dec 02, 2008
On the other hand, this new source of 2 Gt of CO2 is not man made, but purely natural.

Not only is it NOT NEW, but is of no import re. anthropogenic CO2; it's simply part of the background, or baseline level. In mathematical terms, it's a constant; with a derivative of zero, it add nothing to the slope of a line or curve.
Velanarris
3.7 / 5 (3) Dec 05, 2008
On the other hand, this new source of 2 Gt of CO2 is not man made, but purely natural.

Not only is it NOT NEW, but is of no import re. anthropogenic CO2; it's simply part of the background, or baseline level. In mathematical terms, it's a constant; with a derivative of zero, it add nothing to the slope of a line or curve.
And how do you know that when we don't even understand wjhat exactly is part of the baseline?

This is another article showing a need for either better explainations or better research into the current situation.
MikeB
3.7 / 5 (3) Dec 07, 2008
This chart shows the meteoric rise of CO2 since 1959:

http://i224.photo...2000.gif

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.