The coprecipitation of Pu and other radionuclides with CaCO[sub 3]

Journal Article · Wed Mar 31 23:00:00 EST 1993 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(93)90005-H· OSTI ID:6502211

Meece, D E; Benninger, L K ^[1]

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1. Univ. of North Carolina, Chapel Hill (United States)

The record of fallout plutonium concentrations in annual bands of corals is strikingly similar to the record of atmospheric deposition of [sup 90]Sr. This similarity implies that corals may incorporate Pu from seawater with a constant partition coefficient (constant discrimination). To investigate physicochemical aspects of Pu incorporation, the following have been coprecipitated with CaCO[sub 3] (calcite and aragonite): oxidized and reduced Pu; americium, thorium, and uranium as analogs to Pu oxidation states (III, IV, VI), respectively; and [sup 210]Pb as a particle-reactive nuclide which may be incorporated by corals with constant discrimination. Americium, thorium, and lead adsorb onto both calcite and aragonite, with more than 99% of the recovered activity found associated with the solids. Uranium exhibits a behavior consistent with lattice substitution. Partition coefficients for U in aragonite range from 1.8 to 9.8 and vary inversely with pH and/or rate of precipitation. The partition coefficient for U in calcite is less than 0.2 and may be as low as 0.046. Reduced Pu sorbs with 3 to 4% remaining in solution. Oxidized Pu may both sorb and coprecipitate. The coral record for Pb and U results primarily from biological, rather than physicochemical, effects; it is likely that the PU coral record also reflects biological discrimination. 50 refs., 4 figs., 5 tabs.

• OSTI ID: 6502211
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 57:7; ISSN GCACAK; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540330* -- Environment
Aquatic-- Radioactive Materials Monitoring & Transport-- (1990-)
ACTINIDES
ALKALINE EARTH METAL COMPOUNDS
ALPHA DECAY RADIOISOTOPES
AMERICIUM
ANIMALS
ARAGONITE
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALCITE
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CNIDARIA
COELENTERATA
COPRECIPITATION
CORALS
DEPOSITION
ECOLOGICAL CONCENTRATION
ELEMENTS
EVEN-EVEN NUCLEI
FALLOUT
HEAVY NUCLEI
HYDROGEN COMPOUNDS
INVERTEBRATES
ISOTOPES
LEAD 210
LEAD ISOTOPES
METALS
MINERALS
NUCLEI
OXYGEN COMPOUNDS
PARTITION
PLUTONIUM
PRECIPITATION
RADIOISOTOPES
SEAWATER
SEPARATION PROCESSES
THORIUM
TRANSPLUTONIUM ELEMENTS
TRANSURANIUM ELEMENTS
URANIUM
WATER
YEARS LIVING RADIOISOTOPES