Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Oct 14;2(10):1688-1696.
doi: 10.1021/acsestwater.2c00194. Epub 2022 Sep 1.

Time-Integrated Bioavailability Proxy for Actinides in a Contaminated Estuary

Joshua D Chaplin  1 , Marcus Christl  2 , Andrew B Cundy  3 , Phillip E Warwick  3 , Paweł Gaca  3 , François Bochud  1 , Pascal Froidevaux  1
Affiliations

Time-Integrated Bioavailability Proxy for Actinides in a Contaminated Estuary

Joshua D Chaplin et al. ACS ES T Water. .

Abstract

Actinides accumulate within aquatic biota in concentrations several orders of magnitude higher than in the seawater [the concentration factor (CF)], presenting an elevated radiological and biotoxicological risk to human consumers. CFs currently vary widely for the same radionuclide and species, which limits the accuracy of the modeled radiation dose to the public through seafood consumption. We propose that CFs will show less dispersion if calculated using a time-integrated measure of the labile (bioavailable) fraction instead of a specific spot sample of bulk water. Herein, we assess recently developed configurations of the diffusive gradients in thin films (DGT) sampling technique to provide a more accurate predictor for the bioaccumulation of uranium, plutonium, and americium within the biota of the Sellafield-impacted Esk Estuary (UK). We complement DGT data with the cross-flow ultrafiltration of bulk seawater to assess the DGT-labile fraction versus the bulk concentration. Sequential elution of Fucus vesiculosis reveals preferential internalization and strong intracellular binding of less particle-reactive uranium. We find significant variations between CF values in biota calculated using a spot sample versus using DGT, which suggest an underestimation of the CF by spot sampling in some cases. We therefore recommend a revision of CF values using time-integrated bioavailability proxies.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Middle and lower estuary sampling sites (red circles), Esk Estuary, Cumbria, UK with the Sellafield nuclear site situated 10 km north (marked).
Figure 2
Figure 2
Actinide concentrations according to bulk seawater samples and DGT measures, and association with SPM and colloids. Left to right: cbulk according to direct measure of bulk filtered (0.45 μm) seawater; cbulk according to sum of retentate and permeate ultrafiltered fractions (RET + PERM); cDGT according to DGT sampler with 0.39 mm diffusive gel; cDGT according to DGT sampler with 0.78 mm diffusive gel; (right of dotted red line): distribution of fractions associated with SPM (>0.45 μm), associated with colloids (from 10 kDa to 0.45 μm) and truly dissolved (<10 kDa). ± 2σ type A uncertainties.
Figure 3
Figure 3
Actinide fractionation and isotopic reports within F. vesiculosis. Total concentration, fractionation, and isotopic and elemental signatures (atom/atom) of U, Pu, and Am isotopes in F. vesiculosis at middle and lower estuary sites in the Esk Estuary. 241Pu/239Pu ratios decay-corrected to 15.01.2021. ± 2σ type A uncertainties.
Figure 4
Figure 4
Actinide fractionation within F. vesiculosis. Externally and internally accumulated actinide fractions. Internally accumulated fraction distinguished into extracellular, intracellular, and residual fractions.
Figure 5
Figure 5
Comparison of CFs from DGT measures, bulk measures, and IAEA reference CFs. Note: error bars are not visible in every case at the scale of the figure.
See this image and copyright information in PMC

References

    1. Mitchell P. I.; Downes A. B.; Vintró L. L.; McMahon C. A. Studies of the speciation, colloidal association and remobilisation of plutonium in the marine environment. Radioact. Environ. 2001, 1, 175–200. 10.1016/s1569-4860(01)80014-0. - DOI
    1. Howard B. J.; et al. The IAEA handbook on radionuclide transfer to wildlife. J. Environ. Radioact. 2013, 121, 55–74. 10.1016/j.jenvrad.2012.01.027. - DOI - PubMed
    1. Carroll J.; Harms I. H. Uncertainty analysis of partition coefficients in a radionuclide transport model. Water Res. 1999, 33, 2617–2626. 10.1016/s0043-1354(99)00114-1. - DOI
    1. Fisher N. S.; et al. Radionuclide bioconcentration factors and sediment partition coefficients in Arctic Seas subject to contamination from dumped nuclear wastes. Environ. Sci. Technol. 1999, 33, 1979–1982. 10.1021/es9812195. - DOI
    1. Gil-García C.; Tagami K.; Uchida S.; Rigol A.; Vidal M. New best estimates for radionuclide solid-liquid distribution coefficients in soils. Part 3: Miscellany of radionuclides (Cd, Co, Ni, Zn, I, Se, Sb, Pu, Am, and others). J. Environ. Radioact. 2009, 100, 704–715. 10.1016/j.jenvrad.2008.12.001. - DOI - PubMed

LinkOut - more resources