A new study reveals that a significant amount of carbon released into the atmosphere from lakes and rivers in Southern Québec, Canada, is very old – approximately 1,000 to 3,000 years old – challenging the current models of long-term carbon storage in lakes and rivers. Previous studies have suggested that there is a tight coupling between the terrestrial and aquatic environment such that aquatic bacteria rapidly consume modern carbon. The new findings of the respiration of old carbon in aquatic systems suggests there may be significant lags in the coupling between these systems and further represents an additional, unaccounted for source of carbon dioxide to the atmosphere. It is well established that bacteria in northern waters process carbon from their terrestrial surroundings. But the findings from Virginia Commonwealth University in Richmond, Va., and Université du Québec à Montréal in Montreal, Canada, challenge the widely held belief that older carbon sources are not available to bacteria and have been largely removed from the carbon feedback loop between earth and air.
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