Title: Kinetic Model Data: Effect of Calcium on the Bioavailability of Dissolved Uranium (VI) in Plant Roots under Circumneutral pH

Accession Number: doi:10.6073/pasta/a4ba487c3bcab47fed33a03887c0cca0

Link to Dataset: https://portal.edirepository.org/nis/mapbrowse?packageid=edi.492.1

Repository: EDI Data Portal (Environmental Data Initiative)

Data Type(s): Chemical & Chemical Biology, Environmental Science Data, Imaging Data

Organism(s): Brassica juncea

Summary: 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 g 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 g g 1 h 1 in experiments with no added Ca and from 0.73 to 2.07 g 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.