Nitrogen biological cycle

Raven, Peter H., and George B. Johnson. Oxidation-Reduction The Flow of Energy in Living Things and The Nitrogen Cycle. Biology. 3rd ed. Dubuque Wm. C. Brown Publishers, 1992. 

Bioinorganic Chemistry Carbon Cycle Climatology Greenhouse Eeeect and Climate Data Nitrogen Cycle, Biological Ozone Measurements AND Trends Planetary Atmospheres Transport and Fate oe Chemicals in the Environment Tropospheric Chemistry... 

Fig. 1. Biological pathways and processes iavolved ia the nitrogen cycle.

The global nitrogen cycle is often referred to as the nitrogen cycles, since we can view the overall process as the result of the interactions of various biological and abiotic processes. Each of these processes, to a first approximation, can be considered as a self-contained cycle. We have already considered the biological cycle from this perspective (Fig. 12-1), and now we will look at the other processes, the ammonia cycle, the cycle, and the fixation/denitrification cycle. 

Granhall, U. (1981). Biological nitrogen fixation in relation to environmental factors and functioning of natural ecosystems. In "Terrestrial Nitrogen Cycles" (F. E. Clark and T. Rosswall, eds). Ecological Bulletin 33, 131-145. Swedish Natural Science Research Council, Stockholm. 

Falkowski, P.G. 1997 Evolution of the nitrogen cycle and its influence on the biological sequestration of C02 in the ocean. Nature 387 272-275. 

Most biochemistry texts discuss the so-called nitrogen cycle in some depth. Rose (above), for example, touches on the topic a few times. Additional information may be found at the http //academic.reed.edu/biology/Nitrogen, http //www.infoplease.com/ ce6/sci/A0860009.html and http //helios.bto.ed.ac.uk/bto/microbes/nitrogen.htm Websites. 

Figure 14.12 The biological nitrogen cycle. Living organisms acquire nitrogen from incorporation of NH4 into organic molecules.

In denitrification, part of the biological nitrogen cycle, nitrate in the soil is converted via four enzymatic reactions stepwise to nitrite, nitric oxide and nitrous oxide to finally yield gaseous nitrogen. 

The study of the biosynthesis of inorganic nitrogen oxides has a long and distinguished history, principally in the field of microbial and plant nitrogen metabolism (Zumft, 1993). Relatively recently, it has been found that NO, in addition to other species such as nitrite, nitrate, and NjO, is a true intermediate in the biological nitrogen cycle, as described in detail in Chapter 9. 

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