According to a study published in Nature, rivers and streams release about five times more carbon dioxide than all world’s lakes and reservoirs that cover far more of the Earth’s surface.
As per the studies, the inland water of the planet release approximately 2.1giga tons of carbon into the atmosphere each year. Out of this, 1.8giga tons of carbon is released by rivers and streams that cover approximately 241,000 square miles of the Earth. On the other hand, lakes and reservoirs that cover around 1,200,000 square miles release only 0.32giga tons of carbon.
A report in the journal Proceedings of the National Academy of Sciences (PNAS) shows that rivers and streams are the source of at least 10 percent human-caused nitrous oxide emissions to the atmosphere. This is three times the amount estimated by the Intergovernmental Panel on Climate Change (IPCC). The release of nitrous oxide in streams is because of the nitrogen released into the environment by human activities such as fertilizer use and sewage discharge. Fossil fuel combustion and intensive agriculture have also increased the availability of nitrogen in the environment.
Nitrates are present in many fertilizers and are easily transported by water flow into streams and from there to the sea. A major part of the nitrogen from fertilizers is transported is transported into rivers and streams where it is converted to nitrous oxide which is a potent greenhouse gas. Each molecule of nitrous oxide has 300 times the warming potential of a CO2 molecule. The atmospheric nitrous oxide is responsible for 6% of climate change and is the major source of destruction of the ozone layer. The research shows that rivers and streams are responsible for at least 10% of anthropogenic N2O output which is equivalent to 0.6% of total greenhouse gas emissions.
Decreasing the use of factory-produced nitrogen fertilizers is the best way to reduce nitrous oxide in rivers. The efficiency of nitrogen uptake by plants can be increased by farmers by adjusting the timing and frequency of fertilizer application or by changing the kind of fertilizer being used.