Laserfiche WebLink
3 Solubility, Speciation, and <br />Transformations of <br />Selenium in Soils 1 <br />M. A. Elrashidi <br />Electric Power Research Institute <br />Palo Alto, California <br />D. C. Adriano <br />Savannah River Ecology Laboratory <br />Aiken, South Carolina <br />W. L. Lindsay <br />Colorado State University <br />Fort Collins, Colorado <br />ABSTRACT <br />Important selenium (Se) data in the literature are discussed with reference to <br />the solubility relationships of Se minerals and soluble species in cultivated soils. Re- <br />dox potential and pH are the most important parameters controlling the solubility <br />and chemical speciation of Se in cultivated soils. Soils can be classified into three <br />categories. Soils of high redox in grid regions: Selenate (Se04-) is the major species <br />in soil solution. No Selenate minerals are expected to precipitate. Adsorption mechan- <br />ism may control Se concentration in soil solution. Soils of moderate redox in humid <br />regions: Biselenite (HSe03) is predominant at low pH, whereas Se03- is the major <br />species at high pH. Apart from MnSe03, none of the known selenite minerals are <br />stable in soils. Adsorption mechanism may control Se concentration in soil solution. <br />Soils of low redox (i. e., gley and wetland): Monohydrogen selenide (HSe-) is the <br />most important species in soil solution. Only under strongly acidic environment does <br />HZSe° contribute to Se in solution. Elemental Se and metal-selenide minerals can <br />form. Either elemental Se or a metal selenide (i.e., CuZSe, PbSe, etc.) may control <br />Se concentration in soil solution. Furthermore, in this chapter, transformation of <br />Se in soils and effect of soil amendments on Se solubility and plant uptake were dis- <br />cussed with reference to chemical equilibria of Se in soils. <br />'Contribution from the Savannah River Ecology Laboratory, Aiken SC 29801, through con- <br />tract DE-AC09-76SROO-819 with the U.S. Dep. of Energy. <br />Copyright ©1989 Soil Science Society of America and American Society of Agronomy, 677 <br />S. Segoe Rd., Madison, WI 53711, USA. Selenium in Agriculture and the Environment, SSSA <br />Special Publication no. 23. <br />51 <br />