Uranium speciation in moorland river water samples: A comparison of experimental results and computer model predictions

Unsworth, Emily R.; Jones, Phil; Cook, Jennifer M.; Hill, Steve J.

doi:10.1039/b415287e

Cited by 4 publications

(1 citation statement)

References 19 publications

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“…Humic and fulvic acids are believed to be important in the transportation of U, 51 and U is known to bind to the organic fraction, often as the major fraction. 52 The results from this work imply that U was associated with the humic acid fraction, but not the fulvic fraction. For the control soil, the U fractograms were similar to that for the trace elements studied i.e.…”

Section: Preliminary Studiesmentioning

confidence: 65%

Chemical speciation studies on DU contaminated soils using flow field flow fractionation linked to inductively coupled plasma mass spectrometry (FlFFF-ICP-MS)

et al. 2012

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Flow field flow fractionation (FlFFF) in combination with inductively coupled plasma mass spectrometry (ICP-MS) was used to study the chemical speciation of U and trace metals in depleted uranium (DU) contaminated soils. A chemical extraction procedure using sodium pyrophosphate, followed by isolation of humic and fulvic substances was applied to two dissimilar DU contaminated sample types (a sandy soil and a clay-rich soil), in addition to a control soil. The sodium pyrophosphate fractions of the firing range soils (Eskmeals and Kirkcudbright) were found to contain over 50% of the total U (measured after aqua regia digestion), compared to approximately 10% for the control soil. This implies that the soils from the contaminated sites contained a large proportion of the U within more easily mobile soil fractions. Humic and fulvic acid fractions each gave characteristic peak maxima for analytes of interest (Mn, Fe, Cu, Zn, Pb and U), with the fulvic acid fraction eluting at a smaller diameter (approximately 2.1 nm on average) than the humic fraction (approximately 2.4 nm on average). DU in the fulvic acid fraction gave a bimodal peak, not apparent for other trace elements investigated, including natural U. This implies that DU interacts with the fulvic acid fraction in a different way to all other elements studied.

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Section: Preliminary Studiesmentioning

confidence: 65%

Chemical speciation studies on DU contaminated soils using flow field flow fractionation linked to inductively coupled plasma mass spectrometry (FlFFF-ICP-MS)

et al. 2012

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Actinide Speciation and Bioavailability in Fresh and Marine Waters

Markich¹,

Brown²

2018

Encyclopedia of Inorganic and Bioinorganic Chemistry

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The actinides comprise a group of 15 metals (with atomic numbers ranging from 89 to 103) that are all radioactive and occur as cations in natural surface waters. Only the first 10 actinides are covered in this study, as these are the most environmentally relevant, where the dominant oxidation states are as follow: actinium(III), thorium(IV), protactinium(V), uranium(VI), neptunium(V), plutonium(IV) and (V), americium(III), curium(III), berkelium(III), and californium(III). The physicochemical form, or speciation, of an actinide (e.g., free metal ion, or complexes with inorganic or organic ligands) in natural surface waters can be determined using a range of analytical techniques. However, such methods are seldom commercially available and rarely determine a complete distribution of all metal species. A complementary approach, which is more cost effective, time efficient, and predictive, is the application of geochemical speciation modeling, which calculates the percentage distribution of all actinide species based on known or postulated chemical reactions. The general consensus is that geochemical speciation models can provide useful results if applied correctly with an understanding of the differences between simulated and real systems. This is the first study to use an internally consistent equilibrium database within a geochemical model (WHAM) to calculate the speciation of the first 10 actinides across fresh, estuarine, and marine waters that incorporates natural dissolved organic matter (DOM) (i.e., fulvic acid). The speciation of a metal (actinide) largely governs its uptake and/or toxicity (bioavailability) in aquatic organisms. The general consensus is that bioavailability is best predicted by the concentration of the free metal ion (M z+ ) and that metals complexed with most inorganic ligands (e.g., carbonate or sulfate) or natural DOM, typically have low bioavailability. There is also evidence to suggest that colloidal thorium is bioavailable to freshwater organisms. The study correlates observed actinide speciation with bioavailability (where available) or utilizes predicted actinide speciation to determine the likely magnitude of bioavailability, as applied to aquatic organisms. This study also addresses the likely effects of global ocean acidification and increased natural DOM concentrations in fresh surface waters on actinide speciation and bioavailability.

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Impacts of humic substances on the geochemical behaviour of radionuclides

Reiller

Buckau²

2012

Radionuclide Behaviour in the Natural Environment

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Uranium speciation in moorland river water samples: A comparison of experimental results and computer model predictions

Cited by 4 publications

References 19 publications

Chemical speciation studies on DU contaminated soils using flow field flow fractionation linked to inductively coupled plasma mass spectrometry (FlFFF-ICP-MS)

Chemical speciation studies on DU contaminated soils using flow field flow fractionation linked to inductively coupled plasma mass spectrometry (FlFFF-ICP-MS)

Actinide Speciation and Bioavailability in Fresh and Marine Waters

Impacts of humic substances on the geochemical behaviour of radionuclides

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