VATIS UPDATE Article

Researchers at Cornell University, the United States, have discovered a biological mechanism that helps convert nitrogen-based fertilizer into nitrous oxide (N2O), an ozone depleting greenhouse gas (GHG). The paper has been published online Nov. 17 in the Proceedings of the National Academy of Sciences. “The first key to plugging a leak is finding the leak. We now know the key to the leak and what’s leading to it. Nitrous oxide is becoming quite significant in the atmosphere, as there has been a 120 percent increase of nitrous oxide in our atmosphere since pre-industrial times,” said Kyle Lancaster, senior author on the research.

Researchers showed that an enzyme made by the ammonia oxidizing bacterium Nitrosomonas europaea, cytochrome P460, produces N2O after the organism turns ammonia into an intermediate metabolite called hydroxylamine. N. europaea and similar “ammonia-oxidizing bacteria” use hydroxylamine as their fuel source, but too much hydroxylamine can be harmful and the resulting production of N2O is a chemical coping strategy. Researchers theorize that when ammonia-oxidizing bacteria are exposed to high levels of nitrogen compounds, such as wastewater treatment plants, then N2O production via cytochrome P460 will ramp up.

In the atmosphere, GHG are a soup of many species, and that N2O has 300 times the potency of carbon dioxide (CO2). “That’s a staggering number. Nitrous oxide is a really nasty agent to be releasing on a global scale,” said Lancaster. He added that N2O is photochemically reactive and can form free radicals – ozone depleting agents – which aggravates the issue of blanketing Earth’s atmosphere with more gas and raising the globe’s temperature. The United States is among the world leaders in importing nitrogen fertilizer, according to the U.S. Department of Agriculture’s Economic Research Service.