Editor's Note: The EPA report discusses reactive nitrogen compounds, not the inert nitrogen gas found in the atmosphere.
The Environmental Protection Agency and other agencies should take action to cut the amount of nitrogen pollution by 25% over the next 1 to 2 decades, according to EPA's external scientific advisers. EPA, for example, can more tightly regulate emissions from power plants. In a report  released today, the EPA's Science Advisory Board (SAB) also urged the agency to revamp its regulatory and scientific approaches to dealing with nitrogen's multifarious impacts.
Unlike many other pollutants, nitrogen just keeps on causing trouble once it makes it into the environment. In a process called the "nitrogen cascade," a molecule spewed from an automobile's tailpipe will contribute to ozone, then haze, and then acidify soil when it settles onto the ground. After it reaches streams and oceans, nitrogen molecules contribute to algal blooms and return to the air to warm the atmosphere and deplete stratospheric ozone. (These processes happen naturally to some extent, but humans have dramatically increased the amount of nitrogen in the environment through combustion of fossil fuels and use of synthetic fertilizers.)
Because of these interconnected problems, SAB recommends that EPA take a more integrated approach to researching and regulating nitrogen. One reason is to prevent nitrogen-cutting "solutions" from causing inadvertent problems; for example, when manure is treated to prevent nitrogen from reaching coastal waters, the molecule can become more likely to reach the atmosphere and cause trouble there. So the agency should not improve only communication between its researchers who study air and water, but also talk more with scientists at the U.S. departments of agriculture and energy, who also work on nitrogen pollution, the report finds. "It's critical that [communication] be done better and more effectively," says co-author James Galloway of the University of Virginia in Charlottesville. The agency should also try to integrate its regulatory actions on nitrogen, he adds.
The committee examined existing technologies and concluded that they could reduce nitrogen pollution by 25% over the next 1 to 2 decades. The approaches range from curbing emissions from power plants to creating large wetlands to collect nitrogen from fertilizer that runs off fields. Those alone won't solve all the problems caused by nitrogen, but it's a feasible goal to start with, Galloway says.
Some groups want faster results. "The steps the advisory board identifies are a good start, but the consequences of nitrogen pollution for the environment and human well-being are too great to wait 10 to 20 years for a modest reduction. With the right resources and authority from Congress, these agencies can help America's farmers and industry solve this problem quickly," said Noel Gurwick of the Union of Concerned Scientists in a statement.
Charles Benbrook, chief scientist at The Organic Center in Troy, Oregon, added in a statement: "Hopefully this important new report will broaden political support for tough new measures that will, in the end, be good for everyone."