Solubility and Redox Criteria for the Possible Forms of Selenium in Soils

Abstract
The solubility of Se in seven soils indicate that Se concentration in solution is governed primarily by a ferric oxide‐selenite‐adsorption complex (Se oxidation state +4). However, under certain conditions Se may also exist in the oxidation states +6, 0, and −2. The proportions of Se in the four oxidation states are treated theoretically as they are affected by the redox potential, soil pH, and ions with which Se combines.