Natural and Artificial Cycles of Phosphorus

FIGURE 2.6 Natural and artificial cycles of phosphorus. The biocycling of phosphoros on planet Earth is a complex process. It embraces transformations between phosphates, phosphites and phosphides such as PHj (see Chapters 4 and 5) [90]. 

Weathering and leaching processes of millions of years ago led to the transfer of the phosphate to rivers and to the oceans where it was concentrated in shells, bones and marine organisms that were deposited on the ocean floor. Subsequent uplift and other geological movements led to these accumulations becoming dry land deposits. 

In the earth s crust, phosphorus takes second place to carbon, and in comparison with all known elements it takes about twelfth place in natural order of abundance. 

However, these sedimentary deposits, together with the concentrated igneous rock formations, which form the viable commercial sources of the element, represent only a fraction of the total phosphorus that is stiU present in widely distributed igneous form. 

It is believed by some that this widely distributed phosphorus may have originated from nuclear disintegration of silicon in pre-biological ages (Chapter 13.5). 

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