Study tracks negative effects of nitrogen

The global nitrogen cycle has been profoundly altered by human activities which, in turn, affects human health, air and water quality, U.S. researchers say. A multidisciplinary team of scientists from universities, government and the private sector has reviewed the major sources of reactive nitrogen in the United States and their resulting effects on health and the environment, and has offered potential solutions, lead study author Eric Davidson from the Woods Hole Research Center in Massachusetts said. Nitrogen is both an essential nutrient and a pollutant. As a fertilizer it helps feed billions of people, but then, as an agricultural runoff into rivers and oceans, it becomes a pollutant. It also pollutes as a byproduct of fossil fuel combustion, researchers said. Thus it is simultaneously a benefit and a hazard, depending on form, location and quantity, they said. "Nitrogen pollution touches everyone's lives," Davidson, a soil ecologist and executive director of the Woods Hole Research Center, said in a center release Tuesday. "This report highlights the latest understanding of how it's harming human health, choking estuaries with algal growth, and threatening biodiversity, such as by changing how trees grow in our forests." The report urges a systematic, rather than piecemeal, approach to managing nitrogen and its consequences. "There are a variety of impacts due to the human use of nitrogen," researcher James Galloway, a biogeochemist at the University of Virginia, said. "The biggest is a positive one, in that it allows us to grow food for Americans and people in other countries, and we don't want to lose sight of that." But inexpensive abundant food must be weighed against the damage done by nitrogen escaping into the environment, the researchers said. "Yes, we have to feed people, but we also need clean drinking water, clean air, and fisheries in the Gulf of Mexico," Davidson said "The science helps to show those tradeoffs, and where we most stand to gain from improved nutrient management in agriculture."