Rivers are carbon processors, not inert pipelines

Dec 01, 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: Scientists recruit public to help study "The Blob"

Related Stories

Marine ecosystems considered in Kimberley survey

Jun 23, 2015

A multi-disciplinary team is closely monitoring the Kimberley's coastal and estuarine environment to better understand how present levels of organic nitrogen and carbon play a role in sustaining marine productivity.

Recommended for you

Water point 'bank machines' boost Kenya slums

1 hour ago

Around the world people use bank machines to access cash: but in the Kenyan capital's crowded slums, people now use similar machines to access an even more basic requirement—clean water.

H2O: The province of provinces

10 hours ago

Unsafe drinking water is a topic usually connected to the developing world. But the regular recurrence of boil-water advisories, and widely publicised outbreaks in towns like Walkerton and Kashechewan have ...

China announces climate target for Paris deal

13 hours ago

Top carbon polluter China confirmed it will try to cap its rising emissions before 2030 while the U.S. and Brazil pledged to boost renewable energy sources in a series of announcements Tuesday in anticipation ...

User comments : 5

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.