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Learn more about the Nitrogen Cycle

Watch a graphical illustration of the Nitrogen Cycle.

This video shows a graphical illustration of the nitrogen cycle.

The atmosphere contains a massive 3 900 000 petagrams of nitrogen. For comparison, the land surface, the oceans and sediments contain 104, 660 and 400 000 petagrams of nitrogen.

Annually, 0.1 petagrams of nitrogen cycles between the land surface and the atmosphere by denitrification and a combination of nitrogen fixation and deposition. The same happens between the ocean and the atmosphere. A smaller amount of nitrogen (0.005 petagrams) is added to to the atmosphere by lightning each year. During pre-industrial times, 0.03 petagrams of nitrogen was carried by rivers to the oceans, most of which was ultimately buried in sediments.

In 2019 (peak nitrogen), we emitted 0.025 petagrams of nitrogen from industrial sources and, by using nitrogen as a fertilizer, we added 0.2 petagrams of nitrogen to the land surface. This cases the amount of nitrogen carried by rivers to rise to 0.05 petagrams annually, causing eutrophication.

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