Phosphorus minerals

Despite its relatively late discovery, phosphorus is the eleventh most abundant element in Earth s crustal rock. It has been estimated that world reserves of phosphate rock are sufficient to last for several hundred years. Virtually all phosphorus deposits contain apatite, whose general formula is Caj (P04)3 X, where X — OH, or Cl. Fluoroapatite is the least soluble, hence most abundant, of the three apatite minerals. Phosphorus Is found in aqueous systems as HPOq and H2 PO4 ions. In biological organisms, phosphorus is a component of nucleic acids and energy-shuttling molecules such as ATP. 

Plants can also balance their uptake of different nutrients through their production of enzymes and other compounds that help to make specific nutrients more available. Nitrate reductase is required to assimilate NO3 into plant biomass, and its production is triggered by the presence of NO3 in soil solution. Phosphorus limitation induces production of root phosphatase enzymes that cleave organically bound PO4, or side-rophores, which solubihze mineral phosphorus by chelating with other minerals that bind to PO4, such as iron. 

Figure 2 The fate of phosphorus during soil formation can be viewed as the progressive dissolution of primary mineral phosphorus (dominantly apatite), some of which is lost from the system by leaching (decrease in Ptotai). and some of which is reincorporated into nonoccluded, occluded, and organic fractions within the soil. Nonoccluded phosphorus is defined as phosphate sorbed to surfaces of hydrous oxides of iron and aluminum, and calcium carbonate. Occluded phosphorus refers to phosphorus present within the mineral matrix of discrete mineral phases. The initial buildup in organic phosphorus results from organic matter return to soil from vegetation supported by the soil. The subsequent decline...

The use of native labels avoids the difficult task of finding isomorphous derivatives. Sulfur is present in the amino acids methionin and cystein. The latter very often form disulfide bridges between adjacent protein chains. It is an important constituent of rubber and it is also found in fossile fuels and many minerals. Phosphorus is present in ribonucleic acids and in polar head groups of membranes. 

Both an automatic peak-picking routine in the processing software and visual inspection are used to identify peaks. Chemical shifts are then compared with literature reports. Table 2.1 shows some of the biological phosphorus compounds identihed in NMR studies of environmental samples, while Table 2.2 shows peak shifts for phosphorus minerals determined by solid-state spectroscopy. Although this chapter focuses on organic phosphorus, the overlap of peak shifts for biological and mineral phosphorus compounds must be noted. This may complicate the identification of phosphorus species in solid-state spectroscopy, because both biological and mineral phosphorus forms may be present. To further confirm peak shifts, standards such as methylene diphosphonic acid may be added directly to the sample or included as capillary tube inserts in solution NMR (e.g. Koopmans et aL, 2003). 

When the phosphorus source is recently mineralized phosphorus, mycor-... 

Armstrong, R.D., Helyar, K.R. and Prangnell, R. (1 993) Direct assessment of mineral phosphorus availability to tropical crops using P-labelled compounds. Plant and Soil 150, 279-287. 

Fig. 15.5. CENTURY model-simulated patterns for soil organic nitrogen and phosphorus (a) and occluded phosphorus, parent phosphorus, non-occluded mineral phosphorus (labile plus sorbed phosphorus) and organic phosphorus (b) during 4.1 million years of soil development (0-50 cm soil depth). Observed data are plotted on the figure for organic nitrogen and phosphorus.

Phosphorus is the most important of the remaining group 5A elements. It occurs in nature as phosphate minerals. Phosphorus has... 

Phosphorus is the most flame-retardant element known typically 5 wt.% P in PP can provide fire-proofing properties. Organic or mineral phosphorus may be used as flame retardant but generally the performance even at high loading (> 30 wt.%) remains poor and the weak compatibility between the additives and the polymeric matrix leads to a strong decrease of the mechanical properties of PP. 

REQUIRED INTAKE. There is no required level of intake of nucleic acids per se. A nutritious, well-balanced diet provides the precursors necessary for the synthesis of the purines, pyrimidines, and ribose sugar in the body. The only direct requirement is for the mineral phosphorus. Since it is a component of DNA and RNA, it is in every cell of the body. Children and adults require 800 to 1,200 mg daily. 

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