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Phosphates
PhosphatesPure phosphorus is rare in nature. It usually combines with oxygen to form phosphate ions or groups (PO 3- 4 ). Phosphates are considered organic when phosphate groups attach to carbon atoms or inorganic when phosphate ions associate with minerals such as calcium. Organic phosphates provide the energy for most chemical reactions in living cells. The weathering of rocks releases inorganic phosphorus into the soil, and plants take this up and convert it to organic phosphate in their tissue. Humans and animals eat the plants, and when they die, phosphorus is returned to the soil by the action of bacteria and then again taken up by plants. This is the so-called phosphorus cycle. Phosphates are normally a limiting factor for aquatic plant growth. When large amounts of phosphorus enter water, for instance, from farm runoff containing fertilizer, plants can grow out of control. Concentrations as low as 0.01 milligrams per liter (mg/L) can greatly impact a stream. This overfeeding is called eutrophication and may cause an algae bloom. The algae eventually die and sink to the bottom. Bacteria feeding on the algae remove oxygen from the water for respiration. As oxygen levels become lower, animals that need high oxygen levels such as fish will die. This is especially a problem at night when no photosynthesis occurs to replenish the oxygen. If organic oxygen levels drop sufficiently, aerobic organisms can no longer survive and anaerobic bacteria take over. The end products of anaerobic respiration may smell like rotten eggs, fishy, or wormy. see also Agriculture; Fish Kills; Health, Environmental; Wastewater Treatment; Water Pollution. internet resourceUniversity of Maryland. "Impact of Phosphorus on Aquatic Life." Available from http://www.agnr.umd.edu/users. Diana Strnisa |
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Strnisa, Diana. "Phosphates." Pollution A to Z. 2004. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. Strnisa, Diana. "Phosphates." Pollution A to Z. 2004. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1G2-3408100196.html Strnisa, Diana. "Phosphates." Pollution A to Z. 2004. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3408100196.html |
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phosphates
phosphates Phosphate is present in many sedimentary rocks as grains of apatite minerals (calcium phosphate). Rocks that are largely composed of phosphate (phosphorites) are less common but of economic importance as a resource for fertilizers. These phosphorites are formed either directly from a marine source or indirectly through biological uptake.
Marine deposits such as the Upper Cretaceous rocks of North Africa and the Middle East (a leading world resource) form in specific environments. Phosphate in the shallow photic zones is used up by marine organisms, but it will accumulate below this zone if oxygen is sufficiently depleted. This phosphate will form deposits if there is a low influx of sediments, particularly where there are upwelling currents of cold phosphate-rich waters. The phosphate replaces the carbonate in skeletons and lime mud; and phosphate in decaying organic matter can be liberated by bacterial decay. Together this phosphate accumulates as small nodules or crusts and can be seen forming on the ocean shelves today. Biogenic phosphorites may form where phosphate-rich matter, such as bones, teeth, or excrement, is concentrated and cemented together or dissolved and later precipitated. Guano is made from seabird and bat droppings; it may be up to 30 m thick and is an economic resource in the eastern Pacific. These biogenic deposits may be cemented together into rocks or may be dissolved and re-precipitated within limestones as cements or as nodules. N. Mann Bibliography Shelley, R. C. (1988) Applied sedimentology. Academic Press, London. |
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PAUL HANCOCK and BRIAN J. SKINNER. "phosphates." The Oxford Companion to the Earth. 2000. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. PAUL HANCOCK and BRIAN J. SKINNER. "phosphates." The Oxford Companion to the Earth. 2000. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O112-phosphates.html PAUL HANCOCK and BRIAN J. SKINNER. "phosphates." The Oxford Companion to the Earth. 2000. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O112-phosphates.html |
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monazite
monazite , yellow to reddish-brown natural phosphate of the rare earths , mainly the cerium and lanthanum metals, usually with some thorium . Yttrium, calcium, iron, and silica are frequently present. Monazite sand is the crude natural material and is usually purified from other minerals before entering commerce. Monazite occurs in North Carolina, South Carolina, Idaho, Colorado, Montana, and Florida in the United States, and in Brazil, India, Australia, and South Africa. It is an important source of cerium, thorium, and other rare-earth metals and compounds. |
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"monazite." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "monazite." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1E1-monazite.html "monazite." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-monazite.html |
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monazite
monazite Mineral (Ce,La,Y,Th)PO4; sp. gr. 4.9–5.4; hardness 5.0–5.5; monoclinic; clove-brown to reddish-brown to orange and green; off-white streak; resinous to waxy lustre; crystals small, short, prismatic to tabular grains, with larger crystals showing striated faces; cleavage imperfect basal monoclinic; found extensively as an accessory mineral in granites and pegmatites, in gneisses and carbonatites, and concentrated in alluvial sands and placers. It is used as a source of cerium, thorium, and other rare-earth metals and compounds.
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AILSA ALLABY and MICHAEL ALLABY. "monazite." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "monazite." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O13-monazite.html AILSA ALLABY and MICHAEL ALLABY. "monazite." A Dictionary of Earth Sciences. 1999. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-monazite.html |
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phosphates
phosphates Rock or deposit made up largely of inorganic phosphate, commonly calcium phosphate (e.g. the minerals apatite, autunite, monazite, pyromorphite, torbernite, turquoise, vivianite, and wavellite).
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Cite this article
AILSA ALLABY and MICHAEL ALLABY. "phosphates." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "phosphates." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O13-phosphates.html AILSA ALLABY and MICHAEL ALLABY. "phosphates." A Dictionary of Earth Sciences. 1999. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-phosphates.html |
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phosphates
phosphates Salts of phosphoric acid; the form in which the element phosphorus is normally present in foods and body tissues. See also polyphosphates.
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DAVID A. BENDER. "phosphates." A Dictionary of Food and Nutrition. 2005. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. DAVID A. BENDER. "phosphates." A Dictionary of Food and Nutrition. 2005. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O39-phosphates.html DAVID A. BENDER. "phosphates." A Dictionary of Food and Nutrition. 2005. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O39-phosphates.html |
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