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nitrogen. It was known during the 18th century that air contains at least two gases, one of which supports combustion and life, and the other of which does not. Nitrogen was discovered by Daniel Rutherford in 1772, who called it noxious air.
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nitrogen It was known during the 18th century that air contains at least two gases, one of which supports combustion and life, and the other of which does not. Nitrogen was discovered by Daniel Rutherford in 1772, who called it noxious air. The element seemed so inert that Lavoisier named it azote, meaning "without life".
The Atmosphere • 78% N2 • 21% O2 • ~0.0396% CO2
The Paradox that is Nitrogen • N is the most abundant gas in the atmosphere, yet N is the most commonly limiting plant nutrient on the planet! • N is the most abundant gas in the atmosphere, yet human N additions are a concern due to: • acid rain • eutrophication of water and watersheds • US EPA Drinking Water criterion for NO3-N • tropospheric ozone • nitrogen aerosols. • N additions to most forests will increase growth (as can climate warming and rising atmospheric CO2 concentrations!). • For most terrestrial plant communities only inorganic N is available (e.g., NH4+ and NO3-). And while there are thousands of soil organisms that can convert organic-N to NH4+, most are sensitive creatures (e.g., pH, moisture) and very few can nitrify NH4+to NO3- (the favored form for most crops). • The majority of the N deposited on forested watersheds is retained in the watershed, even in N saturated forests.
The Nitrogen ParadoxCliffs Notes Version Although there are huge pools of N in the atmosphere as a gas, in soil as organic matter, and in rocks, nearly all of that is unavailable and most biological systems remain N deficient (except in highly polluted areas). Therefore, the introduction of even small amounts of reactive N (i.e., Nr) have a disproportionately large impact on ecosystem function and ecosystem services to society.
Haber-Bosch Process and Reactive Nitrogen The discovery of the process to fix atmospheric nitrogen (N2) into ammonia (NH4+) by Haber, which was then industrialized by Bosch (an engineer for BASF in Germany), sparked an agricultural revolution that can take credit for the existence of approximately 2 of every 5 humans on the planet today. July 1909 Haber-Bosch Discovery ValclavSmil, Nature 1999 H.H. Janzen 2004
…and gave us the means to produce ≈43% of reactive nitrogen (Nr) in the US today. EPA-SAB-11-013 August 2011 www.epa.gov/sab
N2 atmosphere N Fixation to C-NH2 N Deposition as NH4+ and NO3- Denitrification as NO N2O N2 NH3 Volatilization NO2- terrestrial Organic Matter (C-NH2) NO3- NH4+ Leaching Loss
East Bear Brook Reference West Bear Brook Treated
West Bear Treatments Initiated Nov, 1989 • 1800 eq ha-1 yr-1 (NH4)2SO4 = 25.2 and 28.8 kg ha-1 yr-1 N and S • Added in 6 bi-mo. applications
Atmospheric Inputs (e.g., N, S, CO2) The Watershed Black Box Stream Exports
1 2 3 4 5 6 7 8 Inside the Box • Tree foliar chemistry • Tree physiology • Understory vegetation • Litterfall and decomposition • Roots • Soil chemistry • Soil microbiology • Nitrogen mineralization, nitrification • Soil solutions • Trace gas flux • Groundwater • Stream chemistry • Stream sediments • Hydrology • Ecosystem mass balance • …etc.
http://www.cleanair-coolplanet.org/information/pdf/winterindicators_09.pdfhttp://www.cleanair-coolplanet.org/information/pdf/winterindicators_09.pdf
Runoff from East Bear: 2003-2006 East Bear Stream NO3 West Bear Stream NO3 1996-2006 1988-1989 Navratil et al. 2010
Biogeochemical Controls on Altered Nitrogen Cycling in the Third Decade of Whole-Watershed Simulated N Deposition
