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Effect of Calcium on the Bioavailability of Dissolved Uranium(VI) in Plant Roots under Circumneutral pH

Lookup NU author(s): Dr Lucia Rodriguez Freire


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We integrated field measurements, hydroponic experiments, microscopy, and spectroscopy to investigate the effect of Ca(II) on dissolved U(VI) uptake by plants in 1 mM HCO3 solutions at circumneutral pH. The accumulation of U in plants (3.1–21.3 mg kg–1) from the stream bank of the Rio Paguate, Jackpile Mine, New Mexico served as a motivation for this study. Brassica juncea was the model plant used for the laboratory experiments conducted over a range of U (30–700 μg L–1) and Ca (0–240 mg L–1) concentrations. The initial U uptake followed pseudo-second-order kinetics. The initial U uptake rate (V0) ranged from 4.4 to 62 μg g–1 h–1 in experiments with no added Ca and from 0.73 to 2.07 μg g–1 h–1 in experiments with 12 mg L–1 Ca. No measurable U uptake over time was detected for experiments with 240 mg L–1 Ca. Ternary Ca–U–CO3 complexes may affect the decrease in U bioavailability observed in this study. Elemental X-ray mapping using scanning transmission electron microscopy–energy-dispersive spectrometry detected U–P-bearing precipitates within root cell walls in water free of Ca. These results suggest that root interactions with Ca and carbonate in solution affect the bioavailability of U in plants. This study contributes relevant information to applications related to U transport and remediation of contaminated sites.

Publication metadata

Author(s): El Hayek E, Torres C, Rodriguez-Freire L, Blake JM, De Vore CL, Brearley AJ, Spilde MN, Cabaniss S, Ali AM, Cerrato JM

Publication type: Article

Publication status: Published

Journal: Environmental Science & Technology

Year: 2018

Volume: 52

Issue: 22

Pages: 13089-13098

Print publication date: 20/11/2018

Online publication date: 09/11/2018

Acceptance date: 29/10/2018

ISSN (print): 0013-936X

ISSN (electronic): 1520-5851

Publisher: American Chemical Society


DOI: 10.1021/acs.est.8b02724


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