Scientists have
discovered a surprising similarity between rivers and humans: both
release more carbon dioxide when they work hard. When people are
physically active, their lungs release more carbon dioxide gas than when
they are at rest. Now, researchers from the University of Glasgow have
found for the first time that fast-moving rivers work in a similar
manner, releasing more gas than slower streams.
In a new paper published in Journal of Geophysical Research: Biogeosciences,
a team from the University’s School of Geographical and Earth Sciences
describe their findings from several years of testing around rivers in
two locations in Scotland and four in the Peruvian Amazon. The research
provides more insight into the carbon cycle, the complex process by
which the element carbon is used and transferred between living things,
the land, bodies of water and the atmosphere. Detailed understanding of
the carbon cycle is crucial for determining the impact of human activity
on the world’s climate, but the role of rivers in releasing carbon into
the atmosphere has been given less attention overall by scientists than
the impact of the same process in seas and oceans. University of
Glasgow PhD student Hazel Long and researcher Dr Leena Vihermaa used
infrared gas analysers to quantify the amount of carbon dioxide released
by the rivers in each location. A separate flow meter measured the
velocity of the water streaming past the detector.
Hazel said:
"Carbon is absorbed into waterways through a wide range of sources,
including soil and decaying organic material, which are picked up as
rivers flow from the land to the sea. Recently, the scientific community
has begun paying closer attention to the amount of carbon released into
the atmosphere along the way, and it has turned out to be a very
significant amount, as much as two trillion kilograms of carbon each
year. What we’ve discovered is that the rate of that carbon release is
tied closely to the velocity of the water in the river. Although we
measured the carbon released by rivers separated by thousands of miles,
the results were similar for each. We found that the faster the waters
moved, the more carbon they released."
Susan Waldron, Professor
of Biogeochemistry at the University of Glasgow’s School of Geographical
and Earth Sciences, was also involved in the research. Professor
Waldron said: "Our natural surroundings are rich in carbon, which is
constantly being exchanged in very complicated ways. The role that
rivers play in the carbon cycle is often overlooked, so developing a
better understanding of how rivers release carbon will be critically
important to helping us navigate the future changes caused by global
warming. We’re making the data from this research freely available via
the Environmental Information Data Centre at the Centre for Ecology and
Hydrology, so that anyone with an interest in the topic can use our
findings for their own purposes."
The research was supported by grants from the National Environment Research Council (NERC).
The paper, titled 'Hydraulics are a first order control on CO2 efflux from fluvial systems', is published in Journal of Geophysical Research: Biogeosciences
University of Glasgow