nitrogen

nitrogen - Nitrogen: Multiple and Regional Impacts United...

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Nitrogen: Multiple and Regional Impacts
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For more copies of this document, please contact: US EPA Clean Air Markets Division 1200 Pennsylvania Ave, NW Mail Code 6204N Washington, DC 20460 (202) 564-9620 www.epa.gov/airmarkets United States Environmental Protection Agency Clean Air Market Programs EPA-430-R-01-006 February 2002
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Contents Introduction . ............................................................................... 1 Need For a Regional Approach . .............................................. 2 Structure of the Report . ........................................................... 3 Nitrogen Sources . ...................................................................... 4 Natural Sources. ...................................................................... 4 Man-made Sources . ................................................................ 5 Multiple Transport and Exposure Pathways. ........................... 8 Atmospheric Concentrations . .................................................. 8 Nitrogen Deposition . ................................................................ 9 Regional Effects of Nitrogen Emissions on Health, Visibility & Materials . ........................................ 12 Atmospheric Concentrations . ................................................ 12 Aquatic Concentrations . ........................................................ 15 Regional Ecological Effects of Nitrogen Deposition . ........... 16 Terrestrial Systems . ............................................................... 16 Freshwater Ecosystem Effects . ............................................. 17 Coastal Ecosystem Effects. ................................................... 19 Efforts to Understand and Reduce NO x Emissions. .............. 22 Federal and State Regulations . ............................................. 22 Tracking Nitrogen for Accountability: Long Term Monitoring and Assessment . ................................................. 28 Conclusion. ............................................................................... 31 Glossary . ................................................................................... 33 Bibliography . ............................................................................ 36 Figure References . ................................................................... 37
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1 Introduction N itrogen, 1 the most abundant element in the air 2 we breathe, is essential to plant and animal life. Historically, this airborne compound has persisted in a state of equilibrium as part of a nitrogen cycle embracing air, water, plants, animals, and soils. However, human inputs from electric power generation, industrial activity, transportation, and agriculture have disrupted this balance. These sources have released unprecedented quantities of nitrogen and related compounds to the environment in the past 50 years. Other than nitrogen gas (N 2 ), the two primary categories into which most nitrogen compounds fall are reduced nitrogen, typically dominated by ammonia species (e.g., NH 3 and NH 4 + ), and oxidized nitrogen, composed primarily of nitrogen oxides (NO X ) . Of these two categories of nitrogen compounds, oxidized nitrogen sources are subject to a variety of regulations that limit emissions. On the other hand, sources of reduced nitrogen remain largely unregulated. While this document discusses certain sources and issues with regard to reduced nitrogen, it focuses primarily on atmospheric emissions, deposition, and impacts of oxidized nitrogen (NO X emissions). Nitrogen emissions can affect human health in various ways. Nitrogen dioxide (NO 2 ) is irritating to human lungs, and aids in the formation of particulate matter and ozone . These airborne byproducts of nitrogen emissions can cause premature mortality and chronic respiratory illness such as bron- chitis or asthma, as well as aggravate existing respiratory illness. While less directly linked to atmo- spheric emissions, nitrate contamination of drinking water supplies, largely from agricultural sources, can result in methemoglobinemia or Blue Baby Syndrome.
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nitrogen - Nitrogen: Multiple and Regional Impacts United...

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