Planetary Distribution of Apatite

Precise quantitative estimates of worldwide P distribution are difficult to make but presently available evidence suggests the total quantities lie in the order  

Ocean sediments land soil (generally low concentration) ocean, rivers and lakes (soluble) dry land deposits (mineable concentrates) living matter. 

Phosphorus occurs in combination with calcium in the most abundant and widespread mineral form, which is apatite. Both elements are present in almost all rocks and in the oceans. Both elanents are present in nearly all foods and it is probably no accident that they are utilised by all animal life (Chapters 10 and 11). 

Arsenic is present mainly as arsenate in trace quantities of the element that are found in seawater and in life cells. Comparatively little is known about the natural cycle of this element, which may to some extent be associated with that of phosphorus. Trace quantities may be necessary for some life processes (Chapter 11). 

Two of the most important factors contributing to eutrophication are the high nitrate content of agricultural drainage water and the high phosphate content of domestic sewage (greater than about 0.1 ppm of N or 0.01 ppm of P). 

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