Phosphorus sources

Schwamberger, E. C., and Sims, J. L. (1991). Effects of soil pH, nitrogen source, phosphorus, and molybdenum on early growth and mineral nutrition of burley tobacco. Commun. Soil Sci. Plant Anal. 22 641-57. 

Phosphorus retention in wetlands is an important function in watershed nutrient cycling particularly in drainage basins with significant nonpoint nutrient contributions from agriculture and urban sources. Phosphorus retention in wetlands involves complex intercoupled physical, chemical. 

Sources. Phosphorus is found in most foods because it is a critical component of all living organisms. Dairy products, meat, and fish are particularly rich sources of phosphorus. Phosphorus is also... 

As part of the Canada-Ontario commitment to reduce nonpoint source phosphorus loadings to Lake Erie, the 30 million Soil and Water Environmental Enhancement Program (SWEEP) was initiated in 1986 with a mandate to improve soil and water quality in southwestern Ontario over a five-yr period. Specifically, SWEEP S objective is to reduce agricultural nonpoint phosphorus loadings to Lake Erie by 200 metric tonnes per yr in accordance with the reductions in phosphorus loadings established in the GLWQA (Environment Canada 1987). 

MBE Growth In MBE, the sources for the compound growth are usually purely elemental, for example, metallic gallium, indium, antimony or aluminum, and arsenic, which are evaporated from the so-called Knudsen cells. Nitrogen, which does not exist in solid form, is supplied by plasma sources. Phosphorus is usually generated by subUmation from GaP, as solid elemental P is too reactive in atmosphere and thus diflBcult to handle. The partial pressure or flux of these elemental sources can be controlled by either the temperature of the Knudsen cell or the pressure of the plasma, which do influence the surface stoichiometry at the same time. The generation of intermediate by-products does not take place in the case of MBE. 

Calibration of an arc or spark source is linear over three orders of magnitude, and detection limits are good, often within the region of a few micrograms per gram for elements such as vanadium, aluminum, silicon, and phosphorus. Furthermore, the nature of the matrix material composing the bulk of the sample appears to have little effect on the accuracy of measurement. 

Phosphorus. Eighty-five percent of the phosphoms, the second most abundant element in the human body, is located in bones and teeth (24,35). Whereas there is constant exchange of calcium and phosphoms between bones and blood, there is very Httle turnover in teeth (25). The Ca P ratio in bones is constant at about 2 1. Every tissue and cell contains phosphoms, generally as a salt or ester of mono-, di-, or tribasic phosphoric acid, as phosphoHpids, or as phosphorylated sugars (24). Phosphoms is involved in a large number and wide variety of metaboHc functions. Examples are carbohydrate metaboHsm (36,37), adenosine triphosphate (ATP) from fatty acid metaboHsm (38), and oxidative phosphorylation (36,39). Common food sources rich in phosphoms are Hsted in Table 5 (see also Phosphorus compounds). 

Table 5. Common Food Sources Rich in Phosphorus ...

This method is used for the determination of total chromium (Cr), cadmium (Cd), arsenic (As), nickel (Ni), manganese (Mn), beiylhum (Be), copper (Cu), zinc (Zn), lead (Pb), selenium (Se), phosphorus (P), thalhum (Tl), silver (Ag), antimony (Sb), barium (Ba), and mer-cuiy (Hg) stack emissions from stationaiy sources. This method may also be used for the determination of particulate emissions fohowing the procedures and precautions described. However, modifications to the sample recoveiy and analysis procedures described in the method for the purpose of determining particulate emissions may potentially impacl the front-half mercury determination. 

Looking at these sources from an algal perspective, evolution in habitats in which soluble sources are deficient or, at best, transiently present in time as well as in space, has provided them with mechanisms to take up soluble phosphorus at rapid rates from low concentrations. Most can satisfy their growth needs at SRP concentrations well below 10 molar, even though maximum uptake... 

As the most significant point sources of phosphorus are those from sewage treatment works (STW), control of phosphorus loading is most readily achieved either by precipitation of phosphorus with iron salts (iron(lll) sulfate or iron(lll) chloride) or by biological removal. The latter can only effectively be achieved in STWs using activated sludge and there have been many descriptions of this technique. ... 

In addition to the use of techniques to reduce nutrient run-off at source, entry of nutrients to lakes can be reduced by using pre-lake techniques. These include the use of artificial wetlands on inflow streams, the use of iron salt treatment in pre-lake lagoons or by installing treatment plants to remove phosphorus. 

Most lakes affected by eutrophication will also have significant amounts of phosphorus in their sediments, which can be recycled into the water column (Section 4). The control of this source can be achieved by treating the sediments with iron salts or calcite to bind the phosphorus more tightly into the sediments. These methods have been used to some effect, but consideration has to be given to the quality of the materials used and whether or not the lake can become de-oxygenated in the summer. In the latter case this can be overcome by artificial de-stratification. 

The above description of eutrophication has illustrated the complex nature of the problem, particularly in relation to the influence of nutrients, the multiplicity of sources of phosphorus and the spectrum of its bio-availability. Clearly, the most effective long-term solution to many of our eutrophication problems will be to reduce the nutrient load to affected waters. However, it has also been shown that, because the concentrations of available phosphorus required to impose a control on primary production is very low (e.g. 5-10/rgU total dissolved phosphorus), the reduction of nutrients from any one source alone is unlikely to be effective. 

Another source of departure from stoichiometry occurs when cations are reduced, as for example in tire reduction of zinc oxide to yield an oxygen-defective oxide. The zinc atoms which are formed in tlris process dissolve in the lattice, Zn+ ions entering interstitial sites and the coiTesponding number of electrons being released from these dissolved atoms in much the same manner as was found when phosphorus was dissolved in the Group IV semiconductors. The Kroger-Viirk representation of dris reduction is... 

Nitrogen makes up 78 % of the atmosphere, hence, it is readily available. Ammonia is produced by fixing of atmospheric nitrogen with hydrogen. Mineral sources of phosphorus and potassium are converted to a suitable form for fertilizer. These three elements have other use than fertilizer they are used and interact with other facets of the chemical industry, making a highly complex picture. A schematic of the interactions is presented in Figure 7.2-1. 

By far the largest source of phosphorus is phosphate rock, with some use of phosphatic iron ore, from which phosphorus is obtained as a by-product from the slag. Phosphate rock consists of the insoluble tricalcium phosphate and other materials. For use as a fertilizer, phosphate must be converted to the water soluble form, phosphoric acid (H3PO4) which has three hydrogen atoms, all of which are replaceable by a metal. Tricalcium phosphate, is converted to soluble monocalcium phosphate and to superphosphate, A fertilizer factory, typically, a large installation, characterized by large silos produces year round, but peaks with the demands of the growing season. Phosphorus has many uses other than for fertilizer. 

In contrast to phosphorus esters, sulfur esters are usually cleaved at the carbon-oxygen bond with carbon-fluorine bond formation Cleavage of esteri nf methanesulfonic acid, p-toluenesidfonic acid, and especially trifluoromethane-sulfonic acid (tnflic acid) by fluoride ion is the most widely used method for the conversion of hydroxy compounds to fluoro derivatives Potassium fluoride, triethylamine trihydrofluoride, and tetrabutylammonium fluoride are common sources of the fluoride ion For the cleavage of a variety of alkyl mesylates and tosylates with potassium fluoride, polyethylene glycol 400 is a solvent of choice, the yields are limited by solvolysis of the leaving group by the solvent, but this phenomenon is controlled by bulky substituents, either in the sulfonic acid part or in the alcohol part of the ester [42] (equation 29)... 

For a century after its discovery the only source of phosphorus was urine. The present process of heating phosphate rock with sand and coke was proposed by E. Aubertin and L. Boblique in 1867 and improved by J. B. Readman who introduced the use of an electric furnace. The reactions occurring are still not fully understood, but the overall process can be represented by the idealized equation ... 

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