Not many people see isotope hydrologists on the front line of the fight against climate change. But they are -- studying how to trap greenhouse carbon gas and bury it deep below ground in salty aquifers. The work is one topic being reviewed at the IAEA, when world experts in isotope hydrology meet 21-25 May in Vienna at an international symposium.
Over 280 participants will attend the International Symposium on Advances in Isotope Hydrology and Its Role in Sustainable Water Resources Development. Studies on carbon trapping and other topics from over 60 countries will be presented.
Carbon trapping -- or sequestration in technical terms -- is an emerging research area to combat global warming. It refers to natural or artificial processes that remove carbon from the atmosphere, to reduce or slow rising emissions through interaction with natural "sinks", mainly oceans, deep parts of the Earth´s crust, or plants. In some processes, the carbon dioxide is injected into an underground water source where it dissolves and remains in long-term storage. That´s where isotope hydrologists come in.
"Once the carbon dioxide is trapped in the water you want to make sure it stays put," says Brent Newman, a scientist in the IAEA´s Isotope Hydrology section. "That´s where isotope hydrology comes in. You use isotopes like carbon and oxygen to monitor if the carbon dioxide is leaking or flowing from the aquifer, and to assure the integrity of the aquifer is maintained. For carbon sequestration you need a brine aquifer where the water is thousands of years old. Isotope hydrology can tell you the age of the water. If it´s very old, then it´s unlikely the water is flowing out of the aquifer rapidly enough to be a problem. In addition, many brine aquifers have the capacity to absorb lots of carbon dioxide."
A range of other issues -- from water pollution to protection -- are on the symposium agenda. Participants will hear how isotope hydrology is being used to help countries protect their drinking water. In the Abidjan area of Côte d´Ivoire over recent years, the main source of groundwater quickly became contaminated. Using nitrogen isotopes, hydrologists identified urban sewage as the main contributor contaminating the groundwater.
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The US DOE likes the idea of Carbon Sequestration but not everyone is onboard....
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In addition, check out the Biochar Sequestration research being conducted by Cornell biogeochemist Johannes Lehmann.
Writing in the May 10 issue of the journal Nature, a Cornell biogeochemist describes an economical and efficient way to help offset global warming: Pull carbon dioxide out of the atmosphere by charring, or partially burning, trees, grasses or crop residues without the use of oxygen.
This process, he writes, would double the carbon concentration in the residue, which could be returned to the soil as a carbon sink. The exhaust gases from this process and other biofuel production could then be converted into energy.
This so-called biochar sequestration could offset about 10 percent of the annual U.S. fossil-fuel emissions in any of several scenarios, says Johannes Lehmann, associate professor of soil biogeochemistry in the Department of Crop and Soil Sciences at Cornell.
"Biochar sequestration, combined with bioenergy production, does not require a fundamental scientific advance, and the underlying production technology is robust, clean and simple, making it appropriate for many regions of the world," said Lehmann. "It not only reduces emissions but also sequesters carbon, making it an attractive target for energy subsidies and for inclusion in the global carbon market."
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