GLASGOW, Scotland, Nov. 18 (UPI) -- As human lungs work harder, they expel more carbon dioxide. So too do rivers. Researchers at the University of Glasgow found faster-flowing rivers release more CO2 than those with gentler currents.
The findings, published this week in the Journal of Geophysical Research: Biogeosciences, are the culmination of several years of data collection at two rivers in Scotland and four in the Peruvian Amazon.
Infrared gas analyzers measured the CO2 being released at the six locations, while flow monitors tracked the rivers' currents.
"What we've discovered is that the rate of that carbon release is tied closely to the velocity of the water in the river," study author Hazel Long, a PhD student at Glasgow, explained in a news release. "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."
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The carbon cycle -- the flow of carbon into, out of, and between land, water and living creatures -- is immensely complex. Slowly, researchers have improved their understanding as they study each of the many features and the interplay among them.
The role of rivers, as compared to large bodies of water, is one of the less understood components. Rivers absorb carbon via sediments and decaying organic matter, and release varying levels back into the atmosphere as it's carried downstream.
The latest findings offer a more accurate picture of this mostly ignored exchange. Researchers suggest rivers release upwards of two trillion kilograms of carbon each year.
"Our natural surroundings are rich in carbon, which is constantly being exchanged in very complicated ways," said co-author Susan Waldron, a professor of biogeochemistry at Glasgow's School of Geographical and Earth Sciences. "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."
Researchers are making the data from their study public, so that other scientists can use the information for related studies.
