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Nitrogen fixation: Anthropogenic enhancement-environmental response (1995)
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| Venue: | Global Biogeochemical Cycles |
| Citations: | 75 - 1 self |
BibTeX
@ARTICLE{Galloway95nitrogenfixation:,
author = {James N. Galloway and William H. Schlesinger and Hiram Levy I and Anthony Michaels and Jerald L. Schnoor},
title = {Nitrogen fixation: Anthropogenic enhancement-environmental response},
journal = {Global Biogeochemical Cycles},
year = {1995},
pages = {235--252}
}
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Abstract
Abstract. In the absence of hwnan activities, biotic fiXation is the primary source of reactive N, providing about 90-130 Tg N yr-l (Tg-1012 g) on the continents. Hwnan activities have resulted in the fiXation of an additional::: 140 Tg N yr-l by energy production (:::20 Tg N yr-l), fertilizer production (:::80 Tg N yr-l), and cultivation of crops (e.g., legwnes, rice) (:::40 Tg N yr-l). We can only account for part of this anthropogenic N. N20 is accwnulatin ~ in the atmosphere at a rate of 3 Tg N yr-l. Coastal oceans receive another 41 Tg N yr- via rivers, much of which is buried or denitrified. Open oceans receive 18 Tg N yr-l by atmospheric deposition, which is incorporated into oceanic N pools (e.g., NOj, NV ' The remaining 80 Tg N yr-l are either retained on continents in groundwater, soils, or vegetation or denitrified to N2. Field studies and calculations indicate that uncertainties about the size of each sink can account for the remaining anthropogenic N. Thus although anthropogenic N is clearly accwnulating on continents, we do not know rates of individual processes. We predict the anthropogenic N-fixation rate will increase by about 60 % by the year 2020, primarily due to increased fertilizer use and fossil-fuel combustion. About two-thirds of the increase will occur in Asia, which by 2020 will account for over half of the global anthropogenic N fiXation.
Keyphrases
tg yr-l nitrogen fixation anthropogenic enhancement-environmental response hwnan activity field study primary source fossil-fuel combustion anthropogenic n-fixation rate open ocean oceanic pool increased fertilizer use energy production biotic fixation 90-130 tg yr-l individual process tg yr fertilizer production coastal ocean atmospheric deposition global anthropogenic fixation
