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Biogeochemical Controls of Uranium Bioavailability from the Dissolved Phase in Natural Freshwaters

Croteau, Marie-Noële ; Fuller, Christopher C ; Cain, Daniel J ; Campbell, Kate M ; Aiken, George

Environmental science & technology, 02 August 2016, Vol.50(15), pp.8120-7 [Peer Reviewed Journal]

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  • Title:
    Biogeochemical Controls of Uranium Bioavailability from the Dissolved Phase in Natural Freshwaters
  • Author: Croteau, Marie-Noële ; Fuller, Christopher C ; Cain, Daniel J ; Campbell, Kate M ; Aiken, George
  • Description: To gain insights into the risks associated with uranium (U) mining and processing, we investigated the biogeochemical controls of U bioavailability in the model freshwater species Lymnaea stagnalis (Gastropoda). Bioavailability of dissolved U(VI) was characterized in controlled laboratory experiments over a range of water hardness, pH, and in the presence of complexing ligands in the form of dissolved natural organic matter (DOM). Results show that dissolved U is bioavailable under all the geochemical conditions tested. Uranium uptake rates follow first order kinetics over a range encompassing most environmental concentrations. Uranium uptake rates in L. stagnalis ultimately demonstrate saturation uptake kinetics when exposure concentrations exceed 100 nM, suggesting uptake via a finite number of carriers or ion channels. The lack of a relationship between U uptake rate constants and Ca uptake rates suggest that U does not exclusively use Ca membrane transporters. In general, U bioavailability decreases with increasing pH, increasing Ca and Mg concentrations, and when DOM is present. Competing ions did not affect U uptake rates. Speciation modeling that includes formation constants for U ternary complexes reveals that the aqueous concentration of dicarbonato U species (UO2(CO3)2(-2)) best predicts U bioavailability to L. stagnalis, challenging the free-ion activity model postulate.
  • Is Part Of: Environmental science & technology, 02 August 2016, Vol.50(15), pp.8120-7
  • Identifier: E-ISSN: 1520-5851 ; PMID: 27385165 Version:1 ; DOI: 10.1021/acs.est.6b02406
  • Subjects: Biological Availability ; Uranium -- Chemistry
  • Language: English

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