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A weather balloon rises in the atmosphere. The air in the atmosphere is mostly nitrogen molecules.
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Changing the Nitrogen Cycle, Changing the Planet

Look up into the sky and you look through millions of air molecules, eighty percent of which are nitrogen molecules, two atoms of nitrogen bonded together. Nitrogen is found all over the planet, not just in the sky. It is in living things, air, water, even animal waste. It travels between living and non-living parts of our planet via a process called the nitrogen cycle, one of the Earth’s biogeochemical cycles.

As humans change the way we live on the planet, the way that nitrogen moves around the Earth also changes. Nitrogen atoms may seem small enough to be easily overlooked. We look right through the ones in the air, do we not? Yet recent changes in the nitrogen cycle are causing a very noticeable effect on natural environments and human health. Lakes are clogged with aquatic weeds. Dead zones have formed in areas of the oceans where animals can not survive. Air pollutants that contain nitrogen decreasing air quality and greenhouse gases that contain nitrogen are becoming more common.

Read on to explore two examples of how humans affect the nitrogen cycle and how the changing nitrogen cycle affects humans and ecosystems.

Last modified May 7, 2007 by Lisa Gardiner.

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