Selenium occurrence

Levander, O.A. 1984. The importance of selenium in total parenteral nutrition. Bull. N. Y. Acad Med 60 144-155. Lo, M.T. and E. Sandi. 1980. Selenium occurrence in foods and its toxicological significance. A review. Jour. Environ. Pathol. Toxicol. 4 193-218. 

Biospecific adsorption, 6 396-397, 399 Biospecific binding, in microarray fabrication, 16 385 Biospecific elution, in affinity chromatography, 6 398 Biosphere, selenium occurrence in, 22 78. 

Rock salt semiconductors, 22 141 dating, 21 317-318 selenium occurrence in, 22 78 Rock surface chemistry, in volumetric sweep efficiency, 18 621 Rock varnish, photocatalytic origin of, 19 100-101... 

W. Maher, M. Deaker, D. Jolley, F. Rrikowa, B. Roberts, Selenium occurrence, distribution and speciation in the cockle Anadara trapezia and the mullet Mugil cephalus, Appl. Organomet. Chem., 11 (1997), 313-326. 

LoMT, SandiE. 1980. Selenium Occurrence in foods and its toxicological significance--a review. J Environ Pathol Toxicol 4(1) 193-218. 

USDA. 1938. Selenium occurrence in certain soils in the United States with a discussion. U.S. Department of Agriculture Technical Bulletin No. 601 74. 

Lo MT and Sandi E (1980) Selenium occurrence in foods and its toocicological significance — a review. 

Byers, H. G., "Selenium Occurrence in Certain Soils in the United States,... 

Brown TA, Shrift A (1982) Selenium toxicity tuid tolerance in higher plants. Biol Rev 57 59-84 Broyer TC, Johnson CM, Hudson RP (1972) Selenium and nutrition of Astragalus I effects of selenite or selenate supply on growth tuid selenium content. Plant Soil 36 635-649 Byers HG (1936) Selenium occurrence in certeiin soils in the United States, with a discussion of certain topics. US Department of Agriculture techniceil bulletin, no. 530. USDA, Washington, DC, pp 1-8... 

The Periodic Table. Students are asked to correlate lead, mercury and selenium occurrence on the Periodic Table with airborne exposure risk. Students are asked to name the chemical, predict the common form at RT, and postulate on a potential periodic trend. The relationship between periodicity and exposure is explored. Exposure limits are found in the NIOSH Guide Book (Table V). Students learn to assess and predict from the periodic table. Future, detailed chemical education on using the Periodic Table is emphasized. 

McNeal J.M., Balistrieri L.S. Geochemistry and occurrence of selenium An overview. In Selenium in Agriculture and the Environment, L.M. Jacobs, ed. Madison, IL Soil Science of America, Inc. 1989. 

Occurrence. Selenium is occasionally found as native. Minerals are rare and occur together with the sulphides of chalcophilic metals. Sometimes the minerals are partially oxidized (MSe03 2H20 with M = Ni, Cu, Pb). 

Occurrence. It is found in close association with sulphur and selenium. Tellurium is often found as gold telluride (calaverite), occasionally observed as free element. 

Coleman RG, Delevaux MH (1957) Occurrence of selenium in sulfides from some sedimentary rocks of the western United States. Econ Geol 52(5) 499-527... 

Cooper WC, Bennett KG, Croxton EC (1974) The history, occurrence, and properties of selenium. In Selenium. Zingaro RA, Cooper WC (eds). Van Nostrand Reinhold, New York, p 1-30 Cooper WC, Glover JR (1974) The toxicology of selenium and its compounds. In Selenium. Zingaro RA, Cooper WC (eds). Van Nostrand Reinhold, New York, p 654-674 Cutter GA(1982) Selenium in reducing waters. Science 217(4562) 829-831... 

There is also a significant occurrence of nonprotein D-amino acids in nature.These amino acids have attractive structural variations and remarkable biological properties. However, this chapter will not include details on nonprotein D-amino acids. Selenium-containing amino acids, such as selenocysteine and selenomethionine, are also considered as unusual amino acids. Recently, much interest in selenium-containing amino acids has emerged. More information about selenium-containing amino acids is available in Chapter 5.05. 

New occurrences of selenium were found in rapid succession. J. E. F. Giese of Dorpat, Pleischl of Prague, B. Scholz of Vienna, W. Meissner, J. G. Children, and H. von Meyer all found it in the deposits from various kinds of sulfuric acid. Pleischl detected it in the molybdenite of Schlag-genwald F. Stromeyer, in the volcanic sal ammoniac from the Lipari Islands R. Brandes, in the volcanic sal ammoniac of Lanzarote Island (32). Stromeyer and J. F. Hausmann, DuMenil, J. B. Trommsdorff, J. K. L. Zincken, and Heinrich Rose detected its presence in several minerals (33, 34). 

Occurrence.—Although a relatively rare element, selenium is fairly widespread in nature,1 being frequently found in small quantities both in the combined state in pyrites and sulphide ores 2 and also in the free state in the volcanic sulphur deposits 3 of Italy, Hawaii and the Lipari Islands. In the sulphur deposits the selenium is usually present in the form of an isomorphous mixture with the sulphur. Its occurrence in Swedish pyrites (from Falun) led to the discovery of the element by J. J. Berzelius in 1817,4 during an examination of the deposit formed in the lead chambers of a sulphuric acid plant. Owing to the striking chemical resemblance of the new element to tellurium (see p. 351), Berzelius assigned it the name selenium (Gk. selene, the moon), which, in order to indicate the metalloid nature of the element, is sometimes modified into selenion. 

The analogy of selenium with sulphur is observable in the occurrence of allotropy, although no rigid relationship can be traced between the various forms of the two elements. 

The evidence supplied by the method of formation and the occurrence of isomerism as to analogous structures for the thiosulphates and selenosulphates, is amplified by the chemical behaviour of the potassium alkyl selenosulphates, obtained by treatment of potassium selenosulphates with alkyl halides.1 These, on electrolytic reduction and also on oxidation with hydrogen peroxide, yield the corresponding di-selenides (compare the thiosulphates, p. 203). The structure of the selenosulphates therefore involves a selenium atom directly attached to... 

Occurrence, Extraction and Purification—The Allotropy of Selenium—Colloidal Selenium—General Physical Properties of Selenium—Chemical Properties— Applications of Element—Physiological Action—Atomic Woighl—Valency— Constitution of Selenium Molecule—Detection and Estimation of Selenium. 

Excess dietary selenium has to be avoided because of its potential toxicity at high levels in the diet and the various feed regulations are designed to prevent this occurrence. 

Beath, O.A. 1937. The occurrence of selenium and seleniferous vegetation in Wyoming. II. Seleniferous vegetation in Wyoming. Wyoming Agric. Exp. Stn Bull. 221, 29-64. 

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