View in EDS

Methods for Estimating Adsorbed Uranium(VI) and Distribution Coefficients of Contaminated Sediments.

Saved in:
Bibliographic Details
Title: Methods for Estimating Adsorbed Uranium(VI) and Distribution Coefficients of Contaminated Sediments.
Authors: Matthias Kohler, David T.1 mkohler@usgs.gov, Curtis, Gary P.2, Meece, David E.2, Davis, James A.2
Source: Environmental Science & Technology. 1/1/2004, Vol. 38 Issue 1, p240-247. 8p.
Subject Terms: *Uranium, *Adsorption (Chemistry), *Soil pollution, *Groundwater pollution, *Aquifers, *Solution (Chemistry), Partition coefficient (Chemistry), Migration of uranium
Abstract: Assessing the quantity of U(VI) that participates in sorption/desorption processes in a contaminated aquifer is an important task when investigating U migration behavior. U-contaminated aquifer sediments were obtained from 16 different locations at a former U mill tailings site at Naturita, CO (U.S.A.) and were extracted with an artificial groundwater, a high pH sodium bicarbonate solution, hydroxylamine hydrochloride solution, and concentrated nitric acid. With an isotopic exchange method, both a K[SUBD] value for the specific experimental conditions as well as the total exchangeable mass of U(VI) was determined. Except for one sample, K[SUBD] values determined by isotopic exchange with U-contaminated sediments that were in equilibrium with atmospheric CO[SUB2] agreed within a factor of 2 with K[SUBD] values predicted from a nonelectrostatic surface complexation model (NEM) developed from U(VI) adsorption experiments with uncontaminated sediments. The labile traction of U(VI) and U extracted by the bicarbonate solution were highly correlated (r[SUP2] = 0.997), with a slope of 0.96 ± 0.01. The proximity of the slope to one suggests that both methods likely access the same reservoir of U(VI) associated with the sediments. The results indicate that the bicarbonate extraction method is useful for estimating the mass of labile U(VI) in sediments that do not contain U(IV). In-situ K[SUBD] values calculated from the measured labile U(VI) and the dissolved U(VI) in the Naturita alluvial aquifer agreed within a factor of 3 with in-situ K[SUBD] values predicted with the NEM and groundwater chemistry at each well. [ABSTRACT FROM AUTHOR]
Copyright of Environmental Science & Technology is the property of American Chemical Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: GreenFILE
Description
Abstract:Assessing the quantity of U(VI) that participates in sorption/desorption processes in a contaminated aquifer is an important task when investigating U migration behavior. U-contaminated aquifer sediments were obtained from 16 different locations at a former U mill tailings site at Naturita, CO (U.S.A.) and were extracted with an artificial groundwater, a high pH sodium bicarbonate solution, hydroxylamine hydrochloride solution, and concentrated nitric acid. With an isotopic exchange method, both a K[SUBD] value for the specific experimental conditions as well as the total exchangeable mass of U(VI) was determined. Except for one sample, K[SUBD] values determined by isotopic exchange with U-contaminated sediments that were in equilibrium with atmospheric CO[SUB2] agreed within a factor of 2 with K[SUBD] values predicted from a nonelectrostatic surface complexation model (NEM) developed from U(VI) adsorption experiments with uncontaminated sediments. The labile traction of U(VI) and U extracted by the bicarbonate solution were highly correlated (r[SUP2] = 0.997), with a slope of 0.96 ± 0.01. The proximity of the slope to one suggests that both methods likely access the same reservoir of U(VI) associated with the sediments. The results indicate that the bicarbonate extraction method is useful for estimating the mass of labile U(VI) in sediments that do not contain U(IV). In-situ K[SUBD] values calculated from the measured labile U(VI) and the dissolved U(VI) in the Naturita alluvial aquifer agreed within a factor of 3 with in-situ K[SUBD] values predicted with the NEM and groundwater chemistry at each well. [ABSTRACT FROM AUTHOR]
ISSN:0013936X
DOI:10.1021/es0341236