Selenium geochemistry

In aqueous geochemistry, the important distinguishing property of metals is that, in general, they have a positive oxidation state (donate electrons to form cations in solution), but nonmetals have a negative oxidation state (receive electrons to form anions in solution). In reality, there is no clear dividing line between metals and nonmetals. For example, arsenic, which is classified as a nonmetal, behaves like a metal in its commonest valence states and is commonly listed as such. Other nonmetals, such as selenium, behave more like nonmetals. 

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. 

Belzile, N., et al. 2000. Early diagenetic behavior of selenium in freshwater sediments. Applied Geochemistry, 15, 1439-1454. 

Krouse HR, Thode HG (1962) Thermodynamic properties and geochemistry of isotopic compounds of selenium. Can J Chem 40 367-375... 

Blum JS, Bindi AB, Buzzelli J, Stolz J, Oremland RS (1998) Bacillus arsenicoselenatis, sp. nov., and Bacillus selenitireducens, sp. nov two haloalkaliphiles from Mono Lake, California that respire oxyanions of selenium and arsenic. Arch Microbiol 171 19-30 Brookins DG (1988) Eh-pH Diagrams for Geochemistry. Springer-Verlag, New York... 

Grisafe, D. A., Angino, E. E. Smith, S. M. 1988. Leaching characteristics of a high-calcium fly ash as a function of pH a potential source of selenium toxicity. Applied Geochemistry, 3, 601-608. 

Adsorption of anions at mineral surfaces is important in soils because of the limit this process imposes on the availability of plant nutrients such as P, S, and Mo which occur naturally as anions and are added in anionic form in fertilizers. Anion adsorption is also relevant in geochemistry, ore processing, and other fields where minerals with high surface areas are brought into contact with aqueous solutions of anions. Selenite and goethite were chosen for this study because in Western Australia a selenium deficiency in pastures has been shown to be related to the incidence of white muscle disease in sheep (3), and according to workers quoted by Rosenfeld and Beath (9) selenium in soils of higher... 

Goh, K.-H. and Lim, T.-T. (2004) Geochemistry of inorganic arsenic and selenium in a tropical soil effect of reaction time, pH, and competitive anions on arsenic and selenium adsorption. Chemosphere, 55(6), 849-59. 

Strawn, D Doner, H Zavarin, M. and McHugo, S. (2002) Microscale investigation into the geochemistry of arsenic, selenium, and iron in soil developed in pyritic shale materials. Geoderma, 108(3-4), 237-57. 

Arsenic (As) and selenium (Se) have become increasingly important in environmental geochemistry because of their significance to human health. Their concentrations vary markedly in the environment, partly in relation to geology and partly as a result of human activity. Some of the contamination evident today probably dates back to the first settled civilizations which used metals. 

Environmental and health effects of radionuclides are summarized by Siegel and Bryan, (see Chapter 9.06). Potential environmental effects of hydrocarbons and organic chemicals are addressed in other chapters, and will not be discussed here. Environmental and health effects of arsenic, selenium, and mercury are addressed in greater detail elsewhere in this volume, including Chapters 9.02 and 9.04. Further information on the environmental geochemistry of metals is presented by Callender (see Chapter 9.03). 

Kharaka, Y.K., Ambats, G., Presser, X.S., and Davis, R.A., Removal of selenium from contaminated agricultural drainage water by nanofiltration membranes. Applied Geochemistry, 11, 797, 1996. 

Sindeeva, N. D., Mineralogy, types of deposits, and basic pattern of selenium and tellurium geochemistry, p. 46, Izdatel. Akad. Nauk SSSR, Moscow, (1959), in Russian. Cited on page 634. 

Lakin HW, Davidson DF. 1967. The relation of the geochemistry of selenium to its occurrence in soils. In Muth OH, ed. Symposium Selenium in biomedicine. First International Symposium, Oregon State University. Westport, CN AVI Publishing Co, 27-56. 

Mikkelsen RL, Page AL and Bingham FT (1987) Geochemistry and health in California recent experiences with selenium. Trace Subst Environ Health 20 413-423. 

The discovery in 1957 of a nutritional role for selenium by Schwarz and Foltz (2) has introduced a new and fascinating aspect to the geochemistry of selenium. Selenium is required in the diet of animals at a minimum level of 0.04 ppm and is beneficial to 0.1 ppm at levels above 4 ppm it becomes toxic to animals. In fact, farmers have suffered greater losses because of selenium deficiencies than selenium toxicity. Selenium deficiencies in livestock have been recognized in the United States, Canada, New Zealand, Australia, Scotland, Finland, Sweden, Denmark, France, Germany, Greece, Turkey, and Russia (3). The pasturage in... 

Inorganic pollutants include (a) cationic heavy metals such as lead, cadmium, and nickel, (b) anionic metals and inorganics such as arsenic, chromium, selenium, nitrate and fluoride, and (c) radionuclides such as strontium and uranium. The geochemistry of these pollutants can widely vary and it depends on the specific pollutant type and soil/sediment properties. The speciation and transport of these pollutants also depend on the dynamic changes in the pH and redox potential of the soil that occurs under applied electric potential. The dominant transport process... 

Se (9.4%), Se (7.6%), "Se (23.8), "Se (49.6%), and Se (8.7 %). It usually occurs in the sulfide ores of the heavy metals but rarely as the free element. Volcanic soils are enriched in selenium as are some coal deposits. Selenium compounds are volatilized during the fuel combustion and during copper and other metal smelting and refining. There are numerous overviews of selenium with extensive information on geochemistry and occurrence, seleniferous... 

Welch A. H., Westjohn D. B., Helsel D. R., and Wanty R. B. (2000) Arsenic in ground water of the United States occurrence and geochemistry. Ground Water 38, 589-604. White A. and Dubrovsky N. (1994) Chemical oxidation-reduction controls on selenium mobility in groundwater systems. In Selenium in the Environment (eds. W. T. Frankenberger and S. Benson). Dekker, New York, chap. 8, pp. 185-221. 

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