, Volume 21, Issue 4, pp 1013–1023 | Cite as

Dissolved organic carbon reduces uranium toxicity to the unicellular eukaryote Euglena gracilis

  • Melanie A. Trenfield
  • Jack C. Ng
  • Barry Noller
  • Scott J. Markich
  • Rick A. van Dam


The influence of dissolved organic carbon (DOC), in the form of Suwannee River fulvic acid (SRFA), on uranium (U) toxicity to the unicellular eukaryote, Euglena gracilis (Z strain), was investigated at pH 6. In a background medium without SRFA, exposure of E. gracilis to 57 μg L−1 U resulted in a 50% reduction in growth (IC50). The addition of 20 mg L−1 DOC (as SRFA), reduced U toxicity 4 to 5-fold (IC50 increased to 254 μg L−1 U). This reduction in toxicity was also evident at more sensitive effect levels with a 10% reduction in growth (IC10) occurring at 5 μg L−1 U in the background medium and at 17 μg L−1 U in the SRFA medium, respectively. This amelioration of toxicity with the addition of SRFA was linked to a decrease in the bioavailability of U, with geochemical speciation modelling predicting 84% of U would be complexed by SRFA. The decrease in bioavailability of U in the presence of SRFA was also evident from the 11–14 fold reduction in the cellular concentration of U compared to that of E. gracilis in the background medium. Stepwise multiple linear regression analyses indicated that UO22+ alone explained 51% of the variation in measured U toxicity to E. gracilis. Preliminary U exposures to E. gracilis in the presence of a reactive oxygen species probe, suggest exposure to ≥60 μg L−1 U may induce oxidative stress, but this endpoint was not considered to be a sensitive biological indicator.


Euglena Fulvic acid Uranium Toxicity Freshwater Dissolved organic carbon 

Supplementary material

10646_2012_855_MOESM1_ESM.docx (40 kb)
Supplementary material 1 (DOCX 41 kb)


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Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  • Melanie A. Trenfield
    • 1
    • 2
  • Jack C. Ng
    • 2
  • Barry Noller
    • 3
  • Scott J. Markich
    • 4
  • Rick A. van Dam
    • 1
  1. 1.Ecotoxicology ProgramEnvironmental Research Institute of the Supervising ScientistDarwinAustralia
  2. 2.National Research Centre for Environmental ToxicologyThe University of QueenslandCoopers PlainsAustralia
  3. 3.Centre for Mined Land RehabilitationThe University of QueenslandSt. LuciaAustralia
  4. 4.Aquatic Solutions InternationalDundasAustralia

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