Nitrogen emerges as the latest climate-change threat

McClatchy Washington Bureau: Scientists are raising alarms about yet another threat to Earth's climate and human well-being. This time it's nitrogen, a common element essential to all life. …Now, it's becoming clear that human activities, such as driving cars and raising crops, also are boosting nitrogen to dangerous levels — polluting air and water and damaging human health.

An expanding flock of international scientists is concentrating on the nitrogen threat. There's a reactive nitrogen conference somewhere in the world almost every month. "The public has learned a lot about carbon and its contribution to global change," said James Galloway, an authority on nitrogen at the University of Virginia. "However, they know less about nitrogen and its numerous impacts on environmental issues, including global change."

…Pure nitrogen is a colorless, odorless gas and the largest single component of Earth's atmosphere. Every breath you take is almost 80 percent nitrogen. However, about 1 percent of the stuff is so-called "reactive nitrogen." It combines with other elements, such as oxygen and hydrogen, to form hundreds of thousands of chemical compounds — some beneficial, some harmful.

Many of these compounds are valuable in industry and agriculture. They preserve foods and wine, enhance oil production, make plastics and explosives and fill automobile airbags. They form the building blocks of life: DNA, genes and proteins. Their biggest use is in synthetic fertilizers.

…On the other hand, reactive nitrogen has many negative effects. Its compounds create smog, cause cancer and respiratory disease, and befoul rivers, lakes and coastal waters. They create "dead zones" in the ocean, corrode roads and bridges, weaken the ozone shield and add another greenhouse gas to the already overburdened atmosphere.

"The challenge is to maximize the beneficial uses of reactive nitrogen while minimizing adverse environmental impacts," said a scientific advisory committee to the Environmental Protection Agency in draft report on the problem…

Flood irrigation of an Indian rice field, photo by Sebastianjude, Wikimedia Commons, under the terms of the GNU Free Documentation License, Version 1.2