Oceanic nitrogen fixation

Table Z(.3 Some Recent Extrapolations of Oceanic Nitrogen fixation...

Karl, D., Letelier, R., Tupas, L. et al. (1997). The role of nitrogen fixation in biogeochemical cycling in the subtropical North Pacific Ocean. Nature 388, 533-538. 

Capone, D. G., Bums, J. A., Montoya, J. P., Subramaniam, A., Mahaffey, C., Gunderson, T., Michaels, A. F., and Carpenter, E. J. (2005). Nitrogen fixation by trichodesmium spp. An important source of new nitrogen to the tropical and subtropical North Atlantic Ocean. Global Biogeochem. Cycles 19, GB2024, doi 10.1029/2004GB002331. 

Despite the inertness of N2, the atmospheric N2 pool is available for biological productivity by N2 fixation (N2 —> NH ), which takes place in both the oceanic and the terrestrial environments. Further details about oceanic N2 fixation can be found in Chapter 4. The release of nitrogen as N2 from the fixed inorganic nitrogen pool (i.e. N03, N02 and NH ) is mediated by two microbial processes ... 

Figure Z(.3 Seasonal maps showing the potential for nitrogen fixation in the world oceans. Maps were generated by converting global dust iron fluxes to total dissolved iron and using the relationship shown in between log[Fe ] and nitrogen fixation maximum nitrogen fixation. From Berman-Frank ctaf., 2001 (Fig.4.6) with permission.

Galloway et al. (2004) recently estimated global oceanic N2 fixation to be in the range of 100-200 x 10 g year , roughly equal to the estimate for terrestrial N2 fixation in the absence of human activities. It now appears that upwards of 50% of the nitrogen supporting new production of some tropical and sub-tropical marine upper water column ecosystems could be derived from N2 fixation (Capone et al., 2005 Karl et al., 1997 MahafFey et al., 2005) (see Below). 

Figure if.S Modeled distributions of nitrogen fixation in the worlds oceans. (A) From Moore et al. (2004) with permission. (B) From Deutsch et al. (2007) based on P draw-down with permission. 

Bryceson, I. (1980). Nitrogen fixation and autecology of Oscillatoria erythraea (Ehrenberg) Kuetzing, a planktonic cyanophyte from the coastal waters of Tanzania A preliminary investigation. In Symposium on Coastal and Marine Environment of the Red Sea, Gulf of Aden and tropical western Indian Ocean. Karotoum, Sudan. 

Carpenter, E. J. (1983a). Nitrogen fixation by marine Oscillatoria (Trichodesmium) in the world s oceans. In Nitrogen in the marine environment. (Carpenter, E. J., and Capone, D. G., eds.). Academic Press, New York, pp. 65-103. 

Fogg, G. E. (1978). Nitrogen fixation in the oceans. In Environmental role of Nitrogen-fixing Blue-green Algae and Asymbiotic Bacteria. Ecol. Bull. (Granhall, U., ed.), Vol. 26. Swedish Natural Science Research Council, Stockholm, pp. 11—19. 

HanseU, D., Bates, N., and Olson, D. (2004). Excess nitrate and nitrogen fixation in the North Atlantic Ocean. Mar. Chem. 84, 243—265. 

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