Factors affecting the soil sorption of iodine

Autor: Marsha I. Sheppard, D. H. Thibault, Jude McMurry, P.A. Smith
Rok vydání: 1995
Předmět:
Zdroj: Water, Air, & Soil Pollution. 83:51-67
ISSN: 1573-2932
0049-6979
DOI: 10.1007/bf00482593
Popis: Iodine-129 is an important radionuclide released from nuclear facilities because of its long radioactive half-life and its environmental mobility. Its retention in surface soils has been linked to pH, organic matter, and Fe and Al oxides. Its inorganic solution chemistry indicates I will most likely exist as an anion. Three investigations were carried out to provide information on the role of the inorganic and organic chemistry during sorption of I by soil. Anion competition using Cl− showed that anion exchange plays a role in I sorption in both mineral and organic soils. The presence of Cl decreased the loss of I− from solution by 30 and 50% for an organic and a carbonated sandy soil respectively. The I remaining in solution was associated primarily with dissolved organic carbon (DOC). The loss rate from solution appears to depend on two reactions of I with the soil solids (both mineral and organic) creating both a release to and a loss from solution, and the reaction of I with the DOC (from very low to high molecular weight). Composition analyses of the pore water and the geochemical modelling indicate that I sorption affects the double-charged anion species in solution the most, particularly SO4 −. Iodide introduced to natural bog groundwater at three concentrations (10−3, 10−1 and 10 meq L−1) remained as I− and was not lost from solution quickly, indicating that the association of I with DOC is slow and does not depend on the DOC or I concentration. If sorption of I to soil solids or DOC is not sensitive to concentration, then stable I studies, which by necessity must be carried out at high environmental concentrations, can be linearly extrapolated to radioactive I at much lower molar concentrations.
Databáze: OpenAIRE
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