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Phosphate amendments for chemical immobilization of uranium in contaminated soil
Abstract Uranium (U) contamination is a major environmental problem associated with the mining and processing of nuclear materials for both weapons and power production. When possible, in situ soil remediation techniques are preferable for reducing the risk associated with diffuse low-level U contamination. Uranium is known to form sparingly soluble phosphate compounds that persist in the environment. Therefore, batch experiments were performed to evaluate the efficacy of three phosphate amendments, hydroxyapatite (HA), sodium phytate (IP6) and sodium tripolyphosphate (TPP), to immobilize U in contaminated sediments. The amendments were added at equivalent phosphorus (P) concentrations and then equilibrated under a range of test conditions, with changes in soluble U and Ptotal monitored at pre-set time intervals. Only HA was effective at reducing the soluble U soil fraction when compared to the control, with IP6 and TPP increasing the soluble U soil fraction. After equilibration, changes in contaminant partitioning in the amended sediments were evaluated using operational extraction methods. Sequential extraction results for HA generally indicated a transfer of U from labile to more recalcitrant phases, while the results for IP6 and TPP were more ambiguous.
Graphical abstract Dispersal of organic matter in uranium contaminated Steed Pond sediment amended with HA, IP6, and TPP, and then equilibrated in ARW background solution in an oxic environment. Display Omitted
Highlights Uranium (U) is a major environmental concern associated with nuclear weapons and power production. U contamination is often widely dispersed across the landscape, making conventional reclamation methods impractical. In situ remediation methods that focus on the precipitation of sparingly soluble U-phosphates are promising. Choice of phosphate source is critical since some of the proposed compounds (i.e., IP6 and TPP) may increase U solubility.
Phosphate amendments for chemical immobilization of uranium in contaminated soil
Abstract Uranium (U) contamination is a major environmental problem associated with the mining and processing of nuclear materials for both weapons and power production. When possible, in situ soil remediation techniques are preferable for reducing the risk associated with diffuse low-level U contamination. Uranium is known to form sparingly soluble phosphate compounds that persist in the environment. Therefore, batch experiments were performed to evaluate the efficacy of three phosphate amendments, hydroxyapatite (HA), sodium phytate (IP6) and sodium tripolyphosphate (TPP), to immobilize U in contaminated sediments. The amendments were added at equivalent phosphorus (P) concentrations and then equilibrated under a range of test conditions, with changes in soluble U and Ptotal monitored at pre-set time intervals. Only HA was effective at reducing the soluble U soil fraction when compared to the control, with IP6 and TPP increasing the soluble U soil fraction. After equilibration, changes in contaminant partitioning in the amended sediments were evaluated using operational extraction methods. Sequential extraction results for HA generally indicated a transfer of U from labile to more recalcitrant phases, while the results for IP6 and TPP were more ambiguous.
Graphical abstract Dispersal of organic matter in uranium contaminated Steed Pond sediment amended with HA, IP6, and TPP, and then equilibrated in ARW background solution in an oxic environment. Display Omitted
Highlights Uranium (U) is a major environmental concern associated with nuclear weapons and power production. U contamination is often widely dispersed across the landscape, making conventional reclamation methods impractical. In situ remediation methods that focus on the precipitation of sparingly soluble U-phosphates are promising. Choice of phosphate source is critical since some of the proposed compounds (i.e., IP6 and TPP) may increase U solubility.
Phosphate amendments for chemical immobilization of uranium in contaminated soil
Baker, Matthew R. (author) / Coutelot, Fanny M. (author) / Seaman, John C. (author)
Environmental International ; 129 ; 565-572
2019-03-08
8 pages
Article (Journal)
Electronic Resource
English
Phosphate amendments for chemical immobilization of uranium in contaminated soil
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