Wired.com: Without nitrogen to fertilize crops, the world couldn't feed itself. But if humanity doesn't cut back on the nitrogen it pumps into the environment, we could choke the oceans and ourselves.

That's the troubling takeaway of two articles published today in Science by researchers from the International Nitrogen Initiative. The first, a review of earlier nitrogen pollution studies, charts the incredible growth of nitrogen in the environment. The second quantifies nitrogen added by human activity to the oceans.

"The natural nitrogen cycle has been very heavily influenced by human activity over the last century perhaps even more so than the carbon cycle," said University of East Anglia biogeochemist Peter Liss, a co-author on the second paper.

The problem isn't strictly nitrogen, which comprises more than three-quarters of the air we breathe, but so-called reactive nitrogen. These are analogous to better-known free oxygen radicals: an altered electron configuration makes them especially unstable, and more likely to wreak environmental havoc.