ABSTRACT
Humans are greatly perturbing the global nitrogen cycle. Perhaps the best evidence for this perturbation comes from air trapped in layers of quasipermanent ice in the Arctic and the Antarctic. Ice cores taken from these two polar regions give us a 2000‐year record of the Earth's atmospheric composition. This record indicates a striking constancy in nitrous oxide concentrations, at approximately 285 parts per billion, for nearly 1500 years. (See figure 2.) Since about 1600 AD, however, nitrous oxide concentrations have been increasing, and the present‐day atmospheric burden of this gas is greater than at any other time in the past two millennia. Furthermore, nitrous oxide concentrations continue to increase, currently at a rate of about 0.3% per year. These variations indicate that many nitrogen flows are now larger than in preindustrial times, and other evidence suggests that human activity is responsible. (See figure 1.).
- 1. Intergovernmental Panel on Climate Change, World Meteorological Organization and the United Nations Environment Programme, Climate Change: The IPCC Scientific Assessment, J. T. Houghton, G. J. Jenkins, J. J. Ephraums, eds., Cambridge U.P., Cambridge, England (1990). Google Scholar
- 2. T. Rosswall, in Some Perspectives of the Major Biogeochemical Cycles, G. E. Likens, ed., Wiley, New York (1981), p. 25. Google Scholar
- 3. M. G. Lawrence, W. L. Chameides, P. S. Kasibhatla, H. Levy II, W. Moxim, “Lightning and Atmospheric Chemistry: The Rate of Atmospheric NO Production,” to appear in Handbook of Atmospheric Electrodynamics, vol. 1, CRC Press, Boca Raton, Fla. Google Scholar
- 4. W. H. Schlesinger, Biogeochemistry: An Analysis of Global Change, Academic, San Diego (1991). Google Scholar
- 5. R. Ayres, W. Schlesinger, R. Socolow, in Industrial Ecology and Global Change, R. Socolow, C. Andrews, F. Berkhout, V. Thomas, eds., Cambridge U.P., Cambridge, England (1994), p. 121. Google Scholar
- 6. R. Söderlund, T. Rosswall, in The Natural Environment and the Biogeochemical Cycles, O. Hutzinger, ed., Springer‐Verlag, New York (1982), p. 61. Google Scholar
- 7. J. Sprent, The Ecology of the Nitrogen Cycle, Cambridge U.P., Cambridge, England (1987). Google Scholar
- 8. E. A. Paul, F. E. Clark, Soil Microbiology and Biochemistry, Academic, San Diego (1989). Google Scholar
- 9. J. Harte, A. P. Kinzig, Am. Naturalist 141, 829 (1993). Google ScholarCrossref, ISI
A. P. Kinzig, “Mutualism and Competition Between Plants and Microorganisms: Implications for Nitrogen Allocation in Terrestrial Ecosystems,” PhD dissertation, U. of Calif., Berkeley (1994). , Google Scholar - 10. P. M. Vitousek, W. A. Reiners, BioScience 25, 361 (1975). Google Scholar
P. M. Vitousek, L. R. Walker, in Colonization. Succession, and Stability, A. J. Gray, M. J. Crawley, P. J. Edwards, eds., Blackwell Scientific, Oxford (1986), p. 207. Google Scholar - 11. J. D. Aber, J. M. Melillo, Terrestrial Ecosystems, Saunders, Philadelphia (1991). Google Scholar
P. M. Vitousek, P. A. Matson, in Biogeochemistry of Global Change, R. S. Oremland, ed., Chapman and Hall, New York (1991), p. 193. Google Scholar - 12. Natl. Res. Council, Soil and Water Quality: An Agenda for Agriculture, Natl. Acad. P., Washington, D.C. (1993). Google Scholar
- 13. K. M. Constant, W. F. Sheldrick, World Nitrogen Survey, World Bank, Washington, D.C. (1992). Google Scholar
- 14. W. H. Schlesinger, A. E. Hartley, Biogeochemistry 15, 191 (1992). Google ScholarCrossref
- 15. H. W. Paerl, Can. J. Fisheries Aquatic Sci. 50, 2254 (1993). Google ScholarCrossref, ISI
- 16. J. P. D. Abbatt, M. J. Molina, Annu. Rev. Energy Environment 18, 1 (1993). Google ScholarCrossref
- 17. G. Brasseur, S. Solomon, Aeronomy of the Middle Atmosphere: Chemistry and Physics of the Stratosphere and Mesosphere, Reidel, Dordrecht, The Netherlands (1984). Google Scholar
- 18. P. A. Steudler, R. D. Bowden, J. M. Melillo, J. D. Aber, Nature 341, 314 (1989). Google ScholarCrossref, ISI
- 19. E. B. Rastetter, M. G. Ryan, G. R. Shaver, J. M. Melillo, K. J. Nadelhoffer, J. E. Hobbie, J. D. Aber, Tree Physiol. 9, 101 (1991). Google ScholarCrossref, ISI
- 20. D. W. Schindler, S. E. Bayley, Global Biogeochem. Cycles 7, 717 (1993). Google ScholarCrossref, ISI
- 21. C. R. Carroll, J. H. Vandermeer, P. M. Rosset, Agroecology, McGraw‐Hill, New York (1990). Google Scholar
- 22. US Dept. of Agriculture, Agricultural Statistics 1989, US Govt. Printing Office, Washington, D.C. (1989). Google Scholar
- 23. See, for instance, D. A. Jaffe, in Global Biogeochemical Cycles, S. S. Butcher, R. J. Charlson, G. H. Orians, G. V. Wolfe. eds., Academic, San Diego (1992), p. 263. Google Scholar
- 24. B. N. Richards, The Microbiology of Terrestrial Ecosystems, Longman Scientific and Technical, Harlow, England (1987). Google Scholar
Please Note: The number of views represents the full text views from December 2016 to date. Article views prior to December 2016 are not included.
