Americium interaction with calcite and aragonite surfaces in seawater

Shanbhag, P.M.; Morse, John W.

doi:10.1016/0016-7037(82)90251-4

Cited by 48 publications

(22 citation statements)

References 9 publications

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“…Shanbhay & Morse (1982) have described the uptake of americium onto synthetic calclte and aragonite and shown that aragonite absorbs at a rate 40 times that of calcite. However, for the macrobiogenic calcite of the echinoderm Clypeaster sp.…”

Section: Discussionmentioning

confidence: 99%

Uptake and depuration of 241Am, 239+240pU| 238Pu, 137Cs and 106Ru by Mytilus edulis under natural stress

Clifton¹,

Stevens²,

Hamilton³

1989

Mar. Ecol. Prog. Ser.

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Rates of uptake of 2 4 1~m , I3'Cs and ' 0 6~u by both the soft tissue and the shell of transplanted Mytilus edulis L. were determined; soft tissue data are compared to theoretically derived values based on the biological half-life and the steady state concentration of these isotopes. The rates of loss of 2 4 1~m , U 9 + 2 4 0~~, 2 3 8~~, I3'Cs and I o 6~u by M. edulis under conditions of stress, manifest as extended periods of shell closure as a consequence of high ambient concentrations of copper and zinc and extended periods of aerial exposure, were examined. Both types of stress did not significantly alter the rate of loss of the Pu isotopes, 13'Cs or I o 6~u from the flesh of the mussel but the 2 4 1~m concentration increased significantly over the depuration period of February to June -a probable consequence of the remobilisation of 2 4 1~m associated with the inner nacreous layer of the shell.

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Section: Discussionmentioning

confidence: 99%

Uptake and depuration of 241Am, 239+240pU| 238Pu, 137Cs and 106Ru by Mytilus edulis under natural stress

Clifton¹,

Stevens²,

Hamilton³

1989

Mar. Ecol. Prog. Ser.

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“…1979a,b;Zachara et al, 1991;Zachara et al, 1988). Am3+ adsorption onto calcite was measured by Shanbhag and Morse (1982) and found to be largely irreversible. Similar results were seen by I-liggo and Rees (1986), suggesting the precipitation of an Am-rich phase at the mineral surface.…”

Section: Introductionmentioning

confidence: 99%

Metal sorption to dolomite surfaces

Brady

Papenguth

Kelly

1999

Applied Geochemistry

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Potential human intrusion into the Waste Isolation Pilot Plant (WIPP) might release actinides into the Culebra Dolomite where sorption reactions will affect of radiotoxicity from the repository. Using a limited residence time reactor the authors have measured Ca, Mg, Nd adsorption/exchange as a function of ionic strength, Pcoz, and pH at 25°C. By the same approach, but using as input radioactive tracers, adsorption/exchange of Am, Pu, U, and Np on dolomite were measured as a function of ionic strength, Pcoz, and PH at 25"C. Metal adsorption is tYPical@ favored at high pH. Calcium and Mg adsorb in near-stoichiometric proportions except at high pH. Adsorption of Ca and Mg is diminished at high ionic strengths (e.g., 0.5M NaCl) pointing to association of Na + with the dolomite surflce, and the possibility that Ca and Mg sorb as hydrated, outer-sphere complexes. Sulfate amplifies sorption of Ca and Mg, and possibly Nd as well. Exchange of Nd for surface Ca is favored at high pH, and when Ca levels are low. Exchange for Ca appears to control attachment of actinides to dolomite as well, and high levels of Ca2 + in solution will decrease Kds. At the same time, t~the extent that high Pcojs increase Ca2 + levels, &S will decrease with C02 levels as well, but only if sorbing actinide-carbonate complexes are not observed to form (Amcarbonate complexes appear to sorb; Pu-complexes might sorb as well. U-carbonate complexation leads to resorption). This indirect C02 effect is observed primarily at, and above, neutral pH. High NaCl levels do not appear to atTect to actinide Kds

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“…In contrast, they found that surface precipitation and carbonate solid solution was extensive for thorium and neodymium. Similarly, irreversible sorption and surface precipitation of americium onto carbonates were observed by Shanbhag and Morse (1982) and Higgo and Rees (1986 (Bidoglio et al, 1989); and of Pu(IV), U(VI), and Np(V) in studies of sorption by α-FeOOH (Turner, 1995). Calculated or measured element-specific K d s for natural soils and geomedia for many environmental sites, however, are quite different from these values.…”

Section: Sorptionmentioning

confidence: 85%

Environmental Geochemistry of Radioactive Contamination

Siegel

Bryan

2003

Treatise on Geochemistry

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This report attempts to describe the geochemical foundations of the behavior of radionuclides in the environment. The information is obtained and applied in three interacting spheres of inquiry and analysis: 1) experimental studies and theoretical calculations, 2) field studies of contaminated and natural analog sites and 3) model predictions of radionuclide behavior in remediation and waste disposal. Analyses of the risks from radioactive contamination require estimation of the rates of release and dispersion of the radionuclides through potential exposure pathways. These processes are controlled by solubility, speciation, sorption, and colloidal transport, which are strong functions of the compositions of the groundwater and geomedia as well as the atomic structure of the radionuclides.The chemistry of the fission products is relatively simple compared to the actinides. Because of their relatively short half-lives, fission products account for a large fraction of the radioactivity in nuclear waste for the first several hundred years but do not represent a long-term hazard in the environment. The chemistry of the longer-lived actinides is complex; however, some trends in their behavior can be described. Actinide elements of a given oxidation state have either similar or systematically varying chemical properties due to similarities in ionic size, coordination number, valence, and electron structure. In dilute aqueous systems at neutral to basic pH, the dominant actinide species are hydroxy-and carbonato-complexes, and the solubility-limiting solid phases are commonly oxides, hydroxides or carbonates. In general, actinide sorption will decrease in the presence of ligands that complex with the radionuclide; sorption of the (IV) species of actinides (Np, Pu, U) is generally greater than of the (V) species.The geochemistry of key radionuclides in three different environments is described in this report. These include: 1) low ionic strength reducing waters from crystalline rocks at nuclear waste research 4 sites in Sweden; 2) oxic water from the J-13 well at Yucca Mountain, Nevada, the site of a proposed repository for high level nuclear waste (HLW) in tuffaceous rocks; and 3) reference brines associated with the Waste Isolation Pilot Plant (WIPP). The transport behaviors of radionuclides associated with the Chernobyl reactor accident and the Oklo Natural Reactor are described. These examples span wide temporal and spatial scales and include the rapid geochemical and physical processes important to nuclear reactor accidents or industrial discharges as well as the slower processes important to the geologic disposal of nuclear waste.Application of geochemical information to remediating or assessing the risk posed by radioactive contamination is the final subject of this report. After radioactive source terms have been removed, large volumes of soil and water with low but potentially hazardous levels of contamination may remain. For poorly-sorbing radionuclides, capture of contaminated water and removal of radi...

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Americium interaction with calcite and aragonite surfaces in seawater

Cited by 48 publications

References 9 publications

Uptake and depuration of 241Am, 239+240pU| 238Pu, 137Cs and 106Ru by Mytilus edulis under natural stress

Uptake and depuration of 241Am, 239+240pU| 238Pu, 137Cs and 106Ru by Mytilus edulis under natural stress

Metal sorption to dolomite surfaces

Environmental Geochemistry of Radioactive Contamination

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