No Measurable Changes in 238U/235U due to Desorption鈥揂dsorption of U(VI) from Groundwater at the Rifle, Colorado, Integrated Field Research Challenge Site

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• 作者：Alyssa E. Shiel ; Parker G. Laubach ; Thomas M. Johnson ; Craig C. Lundstrom ; Philip E. Long ; Kenneth H. Williams
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2013
• 出版时间：March 19, 2013
• 年：2013
• 卷：47
• 期：6
• 页码：2535-2541
• 全文大小：322K
• 年卷期：v.47,no.6(March 19, 2013)
• ISSN：1520-5851

文摘

Groundwater samples were collected from the Integrated Field Research Challenge field site in Rifle, Colorado, over the course of a bicarbonate-induced U desorption鈥揳dsorption experiment. Uranium concentrations and high precision U isotopic compositions (²³⁸U/²³⁵U) of these groundwater samples were determined and used to assess the impact of bicarbonate-induced U(VI) desorption from contaminated sediments on the ²³⁸U/²³⁵U of groundwater. The ²³⁸U/²³⁵U of groundwater was not significantly impacted by bicarbonate-induced desorption of U(VI) from mineral surfaces or by adsorption of advecting U(VI) from upgradient locations onto those surfaces after the treatment. Assuming this absence of a significant shift in U isotopic composition associated with desorption鈥揳dsorption applies to other systems, reduction of U(VI) to U(IV) is expected to be the dominant source of U isotopic fractionation associated with removal of U(VI) from pore water as a result of natural and stimulated reductive pathways. Thus, changes in the ²³⁸U/²³⁵U composition of uranium-bearing fluids should be useful in quantifying the extent of reduction.