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Title: Cryogenic Laser Induced Fluorescence Characterization of U(VI) in Hanford Vadose Zone Pore Waters

Abstract

Ambient and liquid helium temperature laser-induced time-resolved uranyl fluorescence spectroscopy was applied to study the speciation of aqueous uranyl solutions containing carbonate and phosphate and two porewater samples obtained by ultra-centrifugation of U(VI)-contaminated sediments. The significantly enhanced fluorescence signal intensity and spectral resolution found at liquid helium temperature allowed, for the first time, direct fluorescence spectroscopic observation of the higher aqueous uranyl complexes with carbonate: UO2(CO3)22-, UO2(CO3)34- and (UO2)2(OH)3CO3-. The porewater samples were non-fluorescent at room temperature. However, at liquid helium temperature, both porewater samples displayed strong, well-resolved fluorescence spectra. Comparisons of the spectroscopic characteristics of the porewaters with those of the standard uranyl-carbonate complexes confirmed that U(VI) in the porewaters existed primarily as UO2(CO3)34-. A small amount of the dicalcium-urano-tricarbonate complex, Ca2UO2(CO3)3, was also observed that was consistent with thermodynamic calculation. The U(VI)-carbonate complex is apparently the mobile species responsible for the subsurface migration of U(VI), even though the majority of the in-ground U(VI) inventory at the site from which the samples were obtained exists as intragrain U(VI)-silicate precipitates.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
15010747
Report Number(s):
PNNL-SA-41205
4597; 4599; KP1301020
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Environmental Science and Technology, 38(5591-5597
Additional Journal Information:
Journal Name: Environmental Science and Technology, 38(5591-5597
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; environmental molecular sciences laboratory

Citation Formats

Wang, Zheming, Zachara, John M, Yantasee, Wassana, Gassman, Paul L, Liu, Chongxuan, and Joly, Alan G. Cryogenic Laser Induced Fluorescence Characterization of U(VI) in Hanford Vadose Zone Pore Waters. United States: N. p., 2004. Web. doi:10.1021/es049512u.
Wang, Zheming, Zachara, John M, Yantasee, Wassana, Gassman, Paul L, Liu, Chongxuan, & Joly, Alan G. Cryogenic Laser Induced Fluorescence Characterization of U(VI) in Hanford Vadose Zone Pore Waters. United States. https://doi.org/10.1021/es049512u
Wang, Zheming, Zachara, John M, Yantasee, Wassana, Gassman, Paul L, Liu, Chongxuan, and Joly, Alan G. 2004. "Cryogenic Laser Induced Fluorescence Characterization of U(VI) in Hanford Vadose Zone Pore Waters". United States. https://doi.org/10.1021/es049512u.
@article{osti_15010747,
title = {Cryogenic Laser Induced Fluorescence Characterization of U(VI) in Hanford Vadose Zone Pore Waters},
author = {Wang, Zheming and Zachara, John M and Yantasee, Wassana and Gassman, Paul L and Liu, Chongxuan and Joly, Alan G},
abstractNote = {Ambient and liquid helium temperature laser-induced time-resolved uranyl fluorescence spectroscopy was applied to study the speciation of aqueous uranyl solutions containing carbonate and phosphate and two porewater samples obtained by ultra-centrifugation of U(VI)-contaminated sediments. The significantly enhanced fluorescence signal intensity and spectral resolution found at liquid helium temperature allowed, for the first time, direct fluorescence spectroscopic observation of the higher aqueous uranyl complexes with carbonate: UO2(CO3)22-, UO2(CO3)34- and (UO2)2(OH)3CO3-. The porewater samples were non-fluorescent at room temperature. However, at liquid helium temperature, both porewater samples displayed strong, well-resolved fluorescence spectra. Comparisons of the spectroscopic characteristics of the porewaters with those of the standard uranyl-carbonate complexes confirmed that U(VI) in the porewaters existed primarily as UO2(CO3)34-. A small amount of the dicalcium-urano-tricarbonate complex, Ca2UO2(CO3)3, was also observed that was consistent with thermodynamic calculation. The U(VI)-carbonate complex is apparently the mobile species responsible for the subsurface migration of U(VI), even though the majority of the in-ground U(VI) inventory at the site from which the samples were obtained exists as intragrain U(VI)-silicate precipitates.},
doi = {10.1021/es049512u},
url = {https://www.osti.gov/biblio/15010747}, journal = {Environmental Science and Technology, 38(5591-5597},
number = ,
volume = ,
place = {United States},
year = {Mon Nov 01 00:00:00 EST 2004},
month = {Mon Nov 01 00:00:00 EST 2004}
}