A new study has found that human activity on the Brazos River in Texas has reversed the natural flow of the river.
“The natural factors that influence carbon dioxide cycling in the Brazos are fairly obvious, and we expected the radiocarbon signature of the river to reflect those influences,” said study co-author Caroline Masiello, assistant professor of Earth science at Rice. “But it looks like whatever the natural process was in the Brazos, in terms of sources and sinks of carbon dioxide, it has been completely overprinted by human activities.”
This is the first study to document such a massive shift on carbon dioxide in a major river as a result solely of human intervention.
With humans adding some 8.5 gigatons of carbon dixoide to the atmosphere each year through the burning of fossil fuels, scientists are increasingly interested in studying how the atmosphere and biosphere exchange carbon dioxide. Plants take up carbon dioxide from the air via photosynthesis and store it in their leaves and stems. Some of that stored carbon gets buried in the soil and locked away for hundreds or thousands of years. But much is also washed into rivers, where rapid decomposition can quickly return it to the atmosphere. Understanding when and where that plant carbon dioxide is returned to the atmosphere is essential if policymakers are to plan effective carbon-sequestration strategies.
One method scientists use to gauge how effectively ecosystems store carbon is radiocarbon dating. The technique involves precisely measuring the amount of radioactive carbon-14 in samples from an ecosystem. Because about half of the carbon-14 atoms in a material will decay and become nitrogen-14 every 5,730 years, scientists can determine the age of a material based on how much carbon-14 it still contains.
This is definitely an interesting phenomenon, and another way in which humans are dramatically affecting the natural environment.
Read more on this story via Rice University.
Image Source: lrargerich