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Rivers are carbon processors, not inert pipelines
December 02, 2008Microorganisms 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."
European Science Foundation
"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."
European Science Foundation
Global Carbon Cycle Current Events and Global Carbon Cycle News RSSNewly Discovered Fat Molecule: An Undersea Killer with an Upside
A chemical culprit responsible for the rapid, mysterious death of phytoplankton in the North Atlantic Ocean has been found by collaborating scientists at Rutgers University and the Woods Hole Oceanographic Institution (WHOI). This same chemical may hold unexpected promise in cancer research.
Seeing the forest and the trees helps cut atmospheric carbon dioxide
Putting a price tag on carbon dioxide emitted by different land use practices could dramatically change the way that land is used - forests become increasingly valuable for storing carbon and overall carbon emissions reductions become cheaper, according to research presented today at the annual meeting of the American Association for the Advancement of Science.
News Release : Carbon Acts Like Rustoleum Around Hydrothermal Vents
The cycling of iron throughout the oceans has been an area of intense research for the last two decades. Oceanographers have spent a lot of time studying what has been affectionately labeled the Geritol effect ever since discovering that the lack of iron is a reason why phytoplankton grow lackadaisically in some of the most nutrient-rich surface waters.
Comet impact theory disproved
New data, published today, disproves the recent theory that a large comet exploded over North America 12,900 years ago, causing a shock wave that travelled across North America at hundreds of kilometres per hour and triggering continent-wide wildfires.
ESA tests laser to measure atmospheric carbon dioxide
A recent ESA campaign has demonstrated how a technique using lasers could be employed to measure carbon dioxide in the atmosphere. The campaign supports one of the main objectives of the candidate Earth Explorer A-SCOPE mission.
ESA leads the way to map boreal forest
How best to map 'boreal' or northern forest with spaceborne radar is the focus of an ESA campaign currently underway in northern Sweden.
MU Scientist Uses Tracer to Predict Ancient Ocean Circulation
Even though the Cretaceous Period ended more than 65 million years ago, clues remain about how the ocean water circulated at that time.
Deep biosphere research points to new methods for recovering petroleum
Miles below us, deep within Earth's crust, life is astir. Organisms there are not the large creatures typically envisioned when thinking of life.
Ice core studies confirm accuracy of climate models
An analysis has been completed of the global carbon cycle and climate for a 70,000 year period in the most recent Ice Age, showing a remarkable correlation between carbon dioxide levels and surprisingly abrupt changes in climate.
University of Miami scientist uncovers miscalculation in geological undersea record
The precise timing of the origin of life on Earth and the changes in life during the past 4.5 billion years has been a subject of great controversy for the past century.
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