Rivers and Streams Emit Five Times as Much Carbon as Lakes and Reservoirs

A new study in the journal Nature suggests that rivers and streams release carbon dioxide at a rate five times greater than the world's lakes and reservoirs combined.

The results are contrary to popular beliefs on greenhouse gas emissions, according to the University of Waterloo, which was involved in the research.

Waterloo research professor Hans Dürr said the study identifies a gap in current carbon cycle knowledge.

"Identifying the sources and amounts of carbon dioxide released from continental water sources has been a gap in understanding the carbon cycle. Our findings show just how much carbon dioxide inland waters release and identified that rivers and streams are the main source, not lakes and reservoirs, as previously thought," Dürr said.

A team of researchers from six nations contributed to the research, which determined the rate at which the various bodies of water released carbon dioxide, a process known as the evasion rate.

The evasion rate for lakes and reservoirs was lower than previously believed, the research team found. However, the evasion rate for streams and rivers was three times higher than previous estimates, and even greater in smaller, fast-flowing streams.

After compiling the data from all the bodies of water sampled in the study, the team extrapolated the data to determine the global carbon dioxide evasion rate. The researchers found the global evasion rate for rivers and streams to be 1.8 billion tons of carbon per year, while the evasion rate for lakes and reservoirs was 0.32 billion tons per yer.

The researchers said the global study provides new insights into how rivers and streams affect the global carbon cycle.

"This study is an example of how new knowledge can be gained by bringing together different tools, techniques and ideas from hundreds of scientists to tackle a global issue," Dürr said. "More integrated, international collaborations like this are needed."