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

作者：Shiel Alyssa E^*; Laubach Parker G; Johnson Thomas M; Lundstrom Craig C; Long Philip E; Williams Kenneth H

来源：Environmental Science & Technology, 2013, 47(6): 2535-2541.

DOI：10.1021/es303913y

Groundwater samples were collected from the Integrated Field Research Challenge field site in Rifle, Colorado, over the course of a bicarbonate-induced U desorption-adsorption experiment. Uranium concentrations and high precision U isotopic compositions (U-238/U-235) of these groundwater samples were determined and used to assess the impact of bicarbonate-induced U(VI) desorption from contaminated sediments on the U-238/U-235 of groundwater. The U-238/U-235 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-adsorption 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 U-238/U-235 composition of uranium-bearing fluids should be useful in quantifying the extent of reduction.

• 出版日期2013-3-19