Emissions of the potent greenhouse gas nitrous oxide from rivers and streams have increased since the 1900s, largely thanks to the use of nitrogen fertilisers in agriculture, according to Australian and international research.
The study found that small rivers were the main contributors to global nitrous oxide emissions from rivers and streams.
Tropical regions and areas with intensively cultivated croplands, such as the central United States, Europe, India, Southeast Asia and east China were the major sources or river nitrous oxide emissions.
On the plus side, these emissions have declined since the early 2000s, but the researchers say this is largely due to plant growth being boosted by the higher levels of another greenhouse gas, carbon dioxide, in the atmosphere.
Source: CSIRO, Auburn University, USA