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Nitrogen is a major nutrient in terrestrial ecosystems and an important catalyst in tropospheric photochemistry. Over the last century human activities have dramatically increased inputs of reactive nitrogen (Nr, the combination of oxidized, reduced and organically bound nitrogen) to the Earth system. Nitrogen cycle perturbations have compromised air quality and human health, acidified ecosystems, and degraded and eutrophied lakes and coastal estuaries [Vitousek et al., 1997a, 1997b; Rabalais, 2002; Howarth et al., 2003; Townsend et al., 2003; Galloway et al., 2004].

To begin to quantify the changes to the global N cycle, we have assembled key flux data and N2O mixing ratios from various sources. The data assembled from different sources include fertilizer production from 1920-2004; manure production from 1860-2004; crop N fixation estimated for three time points, 1860, 1900, 1995; tropospheric N2O mixing ratios from ice core and firn measurements; and tropospheric concentrations to cover the time period 1756-2004. The changing N2O concentrations provide an independent index of changes to the global N cycle in much the same way that changing carbon dioxide concentrations provide an important constraint on the global carbon cycle. The changes to the global N cycle are driven by industrialization, as indicated by fossil fuel NOx emission, and by the intensification of agriculture, as indicted by fertilizer and manure production and crop N2 fixation.

The data set and the science it reflects are by nature interdisciplinary. Making the data set available through the ORNL DAAC is an attempt to make the data set available to the considerable interdisciplinary community studying the N cycle.

Data Citation:

Cite this data set as follows:

Holland, E. A., J. Lee-Taylor, C. Nevison, and J. Sulzman. 2005. Global N Cycle: Fluxes and N2O Mixing Ratios Originating from Human Activity. Data set. Available on-line [] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/797.

More information can be found at


Battle, M., M. Bender, T. Sowers, P. P. Tans, J. H. Butler, J. W. Elkins, J. T. Ellis, T. Conway, N. Zhang, P. Lang and A. D. Clarket. 1996. Atmospheric gas concentrations over the past century measured in air from firn at the South Pole, Nature, 383(6597), 231-235.

Galloway, J. N., and E. B. Cowling. 2002. Reactive Nitrogen and The World: 200 Years of Change, Ambio, 31(2), 64-71.

Galloway, J. N., F. J. Dentener, D. G. Capone, E. W. Boyer, R. W. Howarth, S. P. Seitzinger, G. P. Asner, C. C. Cleveland, P. A. Green, E. A. Holland, D. M. Karl, A. F. Michaels, J. H. Porter, A. R. Townsend, and C. J. Vorosmarty. 2004. Nitrogen Cycles: Past, Present, and Future, Biogeochemistry,70 (2): 153-226, doi:10.1007/s10533-004-0370-0.

Holland, E. A., S. B. Bertman, M. A. Carroll, A. B. Guenther, P. B. Shepson, J. P. Sparks, and J. Lee-Taylor. 2005. U.S. Nitrogen Science Plan Focuses Collaborative Efforts. Eos, Trans. Am. Geophys. Union. 86:253-256.

Howarth, R., Marino, R., and Scavia, D. 2003. Priority Topics for Nutrient Pollution in Coastal Waters: An Integrated National Research Program for the United States. National Ocean Service, pp. 1-24, NOAA.

Machida, T., T. Nakazawa, Y. Fujii, S. Aoki, and O. Watanabe. 1995. Increase in the atmospheric nitrous-oxide concentration during the last 250 years, Geophys Res Lett. 22(21), 2921-2924.

Marland, G., T.A. Boden, and R. J. Andres. 2003. Global, regional, and national fossil fuel CO2 emissions. In Trends: a compendium of data on global change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A.

Nevison, C. D. 1994. A model analysis of the spatial distribution and temporal trends of nitrous oxide sources and sinks, Ph.D. Thesis, Stanford University, 225 pp.

Nevison, C. D., G. Esser, and E. A. Holland, 1996. A Global Model of Changing N2O Emissions from Natural and Perturbed Soils, Climatic Change, 32, 327-378.

Olivier, J. G. J., and J. J. M. Berdowski. 2001. Global emissions sources and sinks. In: Berdowski, J., Guicherit, R. and B.J. Heij (eds.) The Climate System, pp. 33-78. A.A. Balkema Publishers/Swets & Zeitlinger Publishers, Lisse, The Netherlands. ISBN 90 5809 255 0.

Rabalais, N. N. 2002. Nitrogen in aquatic ecosystems, Ambio 31(2), 102-112.

Smil, V. 1990. Nitrogen and phosphorus, in The Earth as transformed by human action, edited by B.L. Turner II et al., Cambridge Univ. Press, New York.

Smil V. 1999. Nitrogen in crop production: an account of global flows. Global Biogeochem. Cycles 13: 647-662. So

Souchu and Etchanchu. 1990. The environmental effects of the intensive application of nitrogen fertilizers in Western Europe: Past problems and future prospects, International Institute for Applied Systems Analysis (IIASA) working paper.

Thompson, T. M., J. H. Butler, B. C. Daube, G. S. Dutton, J. W. Elkins, B. D. Hall, D. F. Hurst, D. B. King, E. S. Kline, B. G. Lafleur, J. Lind, D. J. Mondeel, S. A. Montzka., F. L. Moore, J. D. Nance, J. L. Neu, P. A. Romaskin, A. Scheffer, and W. J. Snible. 2003. Halocarbons and other Atmopsheric Trace Species, Chapter 5 in Climate Monitoring and Diagnostics Laboratory Summary Report #27, NOAA-CMDL, Boulder, CO.

Townsend, A. R., R. W. Howarth, M. S. Booth, C. C. Cleveland, S. K. Collinge, A. P. Dobson, P. R. Epstein, E. A. Holland, D. R. Keeny, and M. A. Malin. 2003. Human health effects of a changing global nitrogen cycle, Frontiers in Ecol., 1(5), 240-246.

Van Aardenne, J. A., F. J. Dentener, J. G. J. Olivier, C. G. M. Klein Goldewijk, and J. Lelieveld. 2001. A 1 x 1 degree resolution dataset of historical anthropogenic trace gas emissions for the period 1890-1990. Global Biogeochemical Cycles,15(4), 909-928.

Vitousek, P. M., J. D. Aber, R. W. Howarth, G. E. Likens, P. A. Matson, D. W. Schindler, W. H. Schlesinger, and D. Tilman. 1997a. Human alteration of the global nitrogen cycle: sources and consequences, Ecol. Appl., 7, 737-750.

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This data is available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC) or the EOS Data Gateway.

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