Humic colloid mediated transport of tetravalent actinides and technetium

Artinger, Robert; Buckau, G.; Zeh, P.; Geraedts, Kathleen; Vancluysen, Jacqueline; Maes, André; Kim, Jae-Il

doi:10.1524/ract.91.12.743.23420

Cited by 37 publications

(19 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In general, they indicate that Th forms strong complexes with humic acids (Nash and Choppin, 1980;Choppin and Nash, 1981;Artinger et al, 2003;Reiller et al, 2003) and acid polysaccharides (Guo et al, 2002b;Quigley et al, 2002;Passow et al, 2006-this issue). Murphy et al (1999) used laboratory experiments to demonstrate that in the presence of humic acids (Perdue et al, 1980) and acid polysaccharide-containing colloidal organic matter (COM) , Th(IV) sorption to hematite was greatly enhanced.…”

Section: Organic Th Speciationmentioning

confidence: 99%

Thorium speciation in seawater

et al. 2006

View full text Add to dashboard Cite

Since the 1960s, thorium isotopes occupy a special place in the oceanographer's toolbox as tracers for determining rates and mechanisms of oceanic scavenging, particle dynamics, and carbon fluxes. Due to their unique and constant production rates from soluble parent nuclides of uranium and radium, their disequilibrium can be used to calculate rates and time scales of sinking particles. In addition, by ratio-ing particulate 234 Th (as well, in principle, other Th-nuclides) to carbon (and other elements), and linking this ratio to the parent-daughter disequilibrium in the water column, it is possible to calculate fluxes of carbon and other elements. Most of these applications are possible with little knowledge of the dissolved chemical properties of thorium, other than its oxidation state (IV) and tendency to strongly sorb to surfaces, i.e., its bparticle-or surface-activityQ. However, the use of any tracer is hindered by a lack of knowledge of its chemical properties. Recent observations in the variability of carbon to 234 Th ratios in different particle types, as well as of associations of Th(IV) with various marine organic biomolecules has led to the need for a review of current knowledge and what future endeavors should be taken to understand the marine chemistry of thorium. D

show abstract

Section: Organic Th Speciationmentioning

confidence: 99%

Thorium speciation in seawater

et al. 2006

View full text Add to dashboard Cite

show abstract

“…Compared to Np(V), which shows a weak interaction with HA, Np(IV) is generally stronger complexed by HA [7,14,17]. The humic colloid-bound Np(IV) species is known to remain stable in groundwater and to be easily mobile in porous aquifer systems [17][18][19]. A strong interaction with HA was also shown for further tetravalent actinides such as Th(IV), U(IV) and Pu(IV) by transport and complexation studies [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Redox stability of neptunium(V) and neptunium(IV) in the presence of humic substances of varying functionality

Schmeide¹,

Bernhard

2009

Radiochimica Acta

View full text Add to dashboard Cite

The reducing properties of humic substances (humic acid (HA) and fulvic acid (FA)) of varying functionality towards Np(V) have been studied under anaerobic conditions between pH 3.5 and pH 9.0 in batch experiments. For Np redox speciation in solution solvent extraction, NIR absorption spectroscopy and ultrafiltration were applied. The reduction rate varied with type of humic substances, solution pH, HA to Np concentration ratio, and equilibration time. In comparison to natural humic substances, synthetic HA with designed redox properties lead to a stronger reduction of Np(V) to Np(IV). The reducing capacities of humic substances towards Np(V) could be correlated to their phenolic/acidic OH group content, which includes both hydroquinone-like moieties and non-quinoid phenols. By applying a synthetic HA with blocked phenolic/acidic OH groups, the dominance of phenolic/acidic OH groups as the redox-active moieties of humic substances was verified.The Np(IV) formed in the course of the experiments is predominantly humic colloid-bound. Np(IV) oxo/hydroxide colloids, that might be formed in addition, are stabilized by adsorbed humic substances. The remaining Np(V) occurs as NpO 2 + ion or Np(V) humate depending on pH. The ability of synthetic HA to effectively maintain Np in the tetravalent state during humate complexation experiments could be shown.

show abstract

“…These analogies are often justified as long as relativistic effects are not taking place [20]. For instance, the similarity in the migration behaviour of Pu(IV) and Th(IV) in the presence of HS has been confirmed [21,22].…”

Section: Introductionmentioning

confidence: 99%

Complexation parameters for the actinides(IV)-humic acid system: a search for consistency and application to laboratory and field observations

Reiller¹,

Evans²,

Szabó³

2008

Radiochimica Acta

View full text Add to dashboard Cite

SummaryThe coherence of actinide(IV) complexation by humic substances (HS) is reviewed and new data are proposed. In a first attempt, the values of independent data from literature on Th(IV), U(IV), and Pu(IV) are collected, selected, and compiled. The data obtained follow the “classical” trend of increasing conditional formation “constants” with pH, led both by the increasing ionisation of HS and by the extensive hydrolysis of the tetravalent actinides. Even though a fair agreement is evident, the experimental uncertainties do not permit a full analogy between the actinides(IV) to be ascertained. In a second attempt, the experiments from which the original data are available were reinterpreted using only one hydrolysis constant set for U(IV) as an example, considering that all actinides(IV) have analogous humic complexation behaviour. Hence, the obtained evolution of conditional formation “constants” is much more coherent and the uncertainties do not permit to distinguish an actinide(IV) from one another. The obtained data are then applied to independent laboratory and

show abstract

Humic colloid mediated transport of tetravalent actinides and technetium

Cited by 37 publications

References 13 publications

Thorium speciation in seawater

Thorium speciation in seawater

Redox stability of neptunium(V) and neptunium(IV) in the presence of humic substances of varying functionality

Complexation parameters for the actinides(IV)-humic acid system: a search for consistency and application to laboratory and field observations

Contact Info

Product

Resources

About