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Nitrogen Pollution Creates a "Cascade" of Environmental Effects, Report Finds
DURHAM, N.H. ? A study co-authored by12 scientists, including John Aber and Scott Ollinger of the University of New Hampshire?s Institute for the Study of Earth, Oceans, and Space (EOS), concludes that increased nitrogen pollution in our air and waterways is causing a wide range of environmental problems. By pulling together relevant scientific data for atmospheric, terrestrial, and aquatic effects, the study demonstrates that there is a "cascade" of environmental consequences being caused by nitrogen.

In the atmosphere, nitrogen oxide emissions lead to ozone formation (smog) and acid precipitation, which have negative consequences for forests and streams and human health. The largest source of atmospheric nitrogen pollution is from automobile and other transportation-based emissions. In coastal waters, the biggest sources of nitrogen pollution are from human wastewater discharge and fertilizer runoff. The nitrogen contained in wastewater is initially derived from foods grown with nitrogen fertilizers. When released to the coastal zone in poorly treated sewage, excess nitrogen has detrimental effects on estuaries, marine food webs and fish populations.

The study, conducted by the scientific team affiliated with the Hubbard Brook Research Foundation (HBRF) in Hanover, N.H., was published in the April issue of the journal BioScience, and is already being used by the attorneys general of New York and the New England states to fight federal efforts to relax emission controls for older power plants. Based on the study?s findings, despite emissions cuts of sulfur dioxide mandated by the 1990 amendments to the Clean Air Act, broad environmental damage from acid rain continues to plague the Northeast. The amount of sulfate (the pollutant derived from sulfur dioxide emissions) deposited in lakes and streams has dropped 30 percent in New England during the 1990s. However, the new study reports, nitrogen emissions from power plants continue to create acid rain.

"This compelling new report illustrates the need to reduce power plant pollution. Now is not the time for the Bush Administration to weaken the Clean Air Act," stated New York Attorney General Eliot Spitzer. The study found that, to achieve recovery from stream acidification by 2050, electric utilities would have to cut nitrogen emissions by 75 percent beyond current levels and emissions from cars would have to be reduced by 90 percent beyond new clean air standards scheduled to take effect next year. Achieving recovery in coastal estuaries will require substantial improvements in the treatment of wastewater.

According to UNH?s Aber, without deep cuts in nitrogen oxide emissions, the cascade effect caused by the pollutant will continue through ecosystems in N.H., the Northeast, and throughout the U.S.

Hubbard Brook has been the focus of scientific inquiry on the impacts of acid rain on a forest ecosystem since 1965. Studies out of Hubbard Brook have had a major impact on federal policies regarding control of sulfur dioxide emissions from power plants and factories.

By David Sims
Communication and Information Coordinator
Institute for the Study of Earth, Oceans, and Space