Washington, DC—New research from two Carnegie scientists has serious implications for the development of management strategies to reduce nutrient runoff in waterways and coastal areas.
Human activities, including agriculture and fossil fuel use, have completely altered the biochemical cycle of nitrogen. In this cycle, nitrogen circulates in various forms through terrestrial, aquatic, and atmospheric systems. In the United States, the amount of nitrogen originating from human sources, particularly fertilizer, is four times the amount that comes from natural sources. The U.S. Environmental Protection Agency estimates that 28 percent of streams and 20 percent of lakes around the